evm: Move to LSM infrastructure

As for IMA, move hardcoded EVM function calls from various places in the
kernel to the LSM infrastructure, by introducing a new LSM named 'evm'
(last and always enabled like 'ima'). The order in the Makefile ensures
that 'evm' hooks are executed after 'ima' ones.

Make EVM functions as static (except for evm_inode_init_security(), which
is exported), and register them as hook implementations in init_evm_lsm().
Also move the inline functions evm_inode_remove_acl(),
evm_inode_post_remove_acl(), and evm_inode_post_set_acl() from the public
evm.h header to evm_main.c.

Unlike before (see commit to move IMA to the LSM infrastructure),
evm_inode_post_setattr(), evm_inode_post_set_acl(),
evm_inode_post_remove_acl(), and evm_inode_post_removexattr() are not
executed for private inodes.

Finally, add the LSM_ID_EVM case in lsm_list_modules_test.c

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Acked-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

ima: Move IMA-Appraisal to LSM infrastructure

A few additional IMA hooks are needed to reset the cached appraisal
status, causing the file's integrity to be re-evaluated on next access.
Register these IMA-appraisal only functions separately from the rest of IMA
functions, as appraisal is a separate feature not necessarily enabled in
the kernel configuration.

Reuse the same approach as for other IMA functions, move hardcoded calls
from various places in the kernel to the LSM infrastructure. Declare the
functions as static and register them as hook implementations in
init_ima_appraise_lsm(), called by init_ima_lsm().

Also move the inline function ima_inode_remove_acl() from the public ima.h
header to ima_appraise.c.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Acked-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

security: Introduce inode_post_setattr hook

In preparation for moving IMA and EVM to the LSM infrastructure, introduce
the inode_post_setattr hook.

At inode_setattr hook, EVM verifies the file's existing HMAC value. At
inode_post_setattr, EVM re-calculates the file's HMAC based on the modified
file attributes and other file metadata.

Other LSMs could similarly take some action after successful file attribute
change.

The new hook cannot return an error and cannot cause the operation to be
reverted.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Paul Moore <paul@paul-moore.com>

evm: Align evm_inode_post_setattr() definition with LSM infrastructure

Change evm_inode_post_setattr() definition, so that it can be registered as
implementation of the inode_post_setattr hook (to be introduced).

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Acked-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

ima: Align ima_inode_post_setattr() definition with LSM infrastructure

Change ima_inode_post_setattr() definition, so that it can be registered as
implementation of the inode_post_setattr hook (to be introduced).

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Acked-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

fs: fix a typo in attr.c

The word "filesytem" should be "filesystem"

Signed-off-by: Jay <merqqcury@gmail.com>
Link: https://lore.kernel.org/r/20240109072927.29626-1-merqqcury@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs: fix doc comment typo fs tree wide

Do the replacement:
s/simply passs @nop_mnt_idmap/simply pass @nop_mnt_idmap/
in the fs/ tree.

Found by chance while working on support for idmapped mounts in fuse.

Cc: Jan Kara <jack@suse.cz>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: <linux-fsdevel@vger.kernel.org>
Cc: <linux-kernel@vger.kernel.org>
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Link: https://lore.kernel.org/r/20231215130927.136917-1-aleksandr.mikhalitsyn@canonical.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs: convert core infrastructure to new timestamp accessors

Convert the core vfs code to use the new timestamp accessor functions.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20231004185239.80830-2-jlayton@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

attr: block mode changes of symlinks

Changing the mode of symlinks is meaningless as the vfs doesn't take the
mode of a symlink into account during path lookup permission checking.

However, the vfs doesn't block mode changes on symlinks. This however,
has lead to an untenable mess roughly classifiable into the following
two categories:

(1) Filesystems that don't implement a i_op->setattr() for symlinks.

Such filesystems may or may not know that without i_op->setattr()
defined, notify_change() falls back to simple_setattr() causing the
inode's mode in the inode cache to be changed.

That's a generic issue as this will affect all non-size changing
inode attributes including ownership changes.

Example: afs

(2) Filesystems that fail with EOPNOTSUPP but change the mode of the
symlink nonetheless.

Some filesystems will happily update the mode of a symlink but still
return EOPNOTSUPP. This is the biggest source of confusion for
userspace.

The EOPNOTSUPP in this case comes from POSIX ACLs. Specifically it
comes from filesystems that call posix_acl_chmod(), e.g., btrfs via

if (!err && attr->ia_valid & ATTR_MODE)
err = posix_acl_chmod(idmap, dentry, inode->i_mode);

Filesystems including btrfs don't implement i_op->set_acl() so
posix_acl_chmod() will report EOPNOTSUPP.

When posix_acl_chmod() is called, most filesystems will have
finished updating the inode.

Perversely, this has the consequences that this behavior may depend
on two kconfig options and mount options:

* CONFIG_POSIX_ACL={y,n}
* CONFIG_${FSTYPE}_POSIX_ACL={y,n}
* Opt_acl, Opt_noacl

Example: btrfs, ext4, xfs

The only way to change the mode on a symlink currently involves abusing
an O_PATH file descriptor in the following manner:

fd = openat(-1, "/path/to/link", O_CLOEXEC | O_PATH | O_NOFOLLOW);

char path[PATH_MAX];
snprintf(path, sizeof(path), "/proc/self/fd/%d", fd);
chmod(path, 0000);

But for most major filesystems with POSIX ACL support such as btrfs,
ext4, ceph, tmpfs, xfs and others this will fail with EOPNOTSUPP with
the mode still updated due to the aforementioned posix_acl_chmod()
nonsense.

So, given that for all major filesystems this would fail with EOPNOTSUPP
and that both glibc (cf. [1]) and musl (cf. [2]) outright block mode
changes on symlinks we should just try and block mode changes on
symlinks directly in the vfs and have a clean break with this nonsense.

If this causes any regressions, we do the next best thing and fix up all
filesystems that do return EOPNOTSUPP with the mode updated to not call
posix_acl_chmod() on symlinks.

But as usual, let's try the clean cut solution first. It's a simple
patch that can be easily reverted. Not marking this for backport as I'll
do that manually if we're reasonably sure that this works and there are
no strong objections.

We could block this in chmod_common() but it's more appropriate to do it
notify_change() as it will also mean that we catch filesystems that
change symlink permissions explicitly or accidently.

Similar proposals were floated in the past as in [3] and [4] and again
recently in [5]. There's also a couple of bugs about this inconsistency
as in [6] and [7].

Link: https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/fchmodat.c;h=99527a3727e44cb8661ee1f743068f108ec93979;hb=HEAD [1]
Link: https://git.musl-libc.org/cgit/musl/tree/src/stat/fchmodat.c [2]
Link: https://lore.kernel.org/all/20200911065733.GA31579@infradead.org [3]
Link: https://sourceware.org/legacy-ml/libc-alpha/2020-02/msg00518.html [4]
Link: https://lore.kernel.org/lkml/87lefmbppo.fsf@oldenburg.str.redhat.com [5]
Link: https://sourceware.org/legacy-ml/libc-alpha/2020-02/msg00467.html [6]
Link: https://sourceware.org/bugzilla/show_bug.cgi?id=14578#c17 [7]
Reviewed-by: Aleksa Sarai <cyphar@cyphar.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org # please backport to all LTSes but not before v6.6-rc2 is tagged
Suggested-by: Christoph Hellwig <hch@lst.de>
Suggested-by: Florian Weimer <fweimer@redhat.com>
Message-Id: <20230712-vfs-chmod-symlinks-v2-1-08cfb92b61dd@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs: convert to ctime accessor functions

In later patches, we're going to change how the inode's ctime field is
used. Switch to using accessor functions instead of raw accesses of
inode->i_ctime.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Message-Id: <20230705190309.579783-23-jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

nfs: use vfs setgid helper

We've aligned setgid behavior over multiple kernel releases. The details
can be found in the following two merge messages:
cf619f891971 ("Merge tag 'fs.ovl.setgid.v6.2')
426b4ca2d6a5 ("Merge tag 'fs.setgid.v6.0')
Consistent setgid stripping behavior is now encapsulated in the
setattr_should_drop_sgid() helper which is used by all filesystems that
strip setgid bits outside of vfs proper. Switch nfs to rely on this
helper as well. Without this patch the setgid stripping tests in
xfstests will fail.

Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Message-Id: <20230313-fs-nfs-setgid-v2-1-9a59f436cfc0@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs: port vfs{g,u}id helpers to mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

fs: port i_{g,u}id_into_vfs{g,u}id() to mnt_idmap

Convert to struct mnt_idmap.
Remove legacy file_mnt_user_ns() and mnt_user_ns().

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

fs: port i_{g,u}id_{needs_}update() to mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

fs: port privilege checking helpers to mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

fs: port inode_owner_or_capable() to mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

fs: port xattr to mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

fs: port ->permission() to pass mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

fs: port ->setattr() to pass mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

fs: port vfs_*() helpers to struct mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

filelock: move file locking definitions to separate header file

The file locking definitions have lived in fs.h since the dawn of time,
but they are only used by a small subset of the source files that
include it.

Move the file locking definitions to a new header file, and add the
appropriate #include directives to the source files that need them. By
doing this we trim down fs.h a bit and limit the amount of rebuilding
that has to be done when we make changes to the file locking APIs.

Reviewed-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Acked-by: Chuck Lever <chuck.lever@oracle.com>
Acked-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: Steve French <stfrench@microsoft.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Jeff Layton <jlayton@kernel.org>

attr: use consistent sgid stripping checks

Currently setgid stripping in file_remove_privs()'s should_remove_suid()
helper is inconsistent with other parts of the vfs. Specifically, it only
raises ATTR_KILL_SGID if the inode is S_ISGID and S_IXGRP but not if the
inode isn't in the caller's groups and the caller isn't privileged over the
inode although we require this already in setattr_prepare() and
setattr_copy() and so all filesystem implement this requirement implicitly
because they have to use setattr_{prepare,copy}() anyway.

But the inconsistency shows up in setgid stripping bugs for overlayfs in
xfstests (e.g., generic/673, generic/683, generic/685, generic/686,
generic/687). For example, we test whether suid and setgid stripping works
correctly when performing various write-like operations as an unprivileged
user (fallocate, reflink, write, etc.):

echo "Test 1 - qa_user, non-exec file $verb"
setup_testfile
chmod a+rws $junk_file
commit_and_check "$qa_user" "$verb" 64k 64k

The test basically creates a file with 6666 permissions. While the file has
the S_ISUID and S_ISGID bits set it does not have the S_IXGRP set. On a
regular filesystem like xfs what will happen is:

sys_fallocate()
-> vfs_fallocate()
-> xfs_file_fallocate()
-> file_modified()
-> __file_remove_privs()
-> dentry_needs_remove_privs()
-> should_remove_suid()
-> __remove_privs()
newattrs.ia_valid = ATTR_FORCE | kill;
-> notify_change()
-> setattr_copy()

In should_remove_suid() we can see that ATTR_KILL_SUID is raised
unconditionally because the file in the test has S_ISUID set.

But we also see that ATTR_KILL_SGID won't be set because while the file
is S_ISGID it is not S_IXGRP (see above) which is a condition for
ATTR_KILL_SGID being raised.

So by the time we call notify_change() we have attr->ia_valid set to
ATTR_KILL_SUID | ATTR_FORCE. Now notify_change() sees that
ATTR_KILL_SUID is set and does:

ia_valid = attr->ia_valid |= ATTR_MODE
attr->ia_mode = (inode->i_mode & ~S_ISUID);

which means that when we call setattr_copy() later we will definitely
update inode->i_mode. Note that attr->ia_mode still contains S_ISGID.

Now we call into the filesystem's ->setattr() inode operation which will
end up calling setattr_copy(). Since ATTR_MODE is set we will hit:

if (ia_valid & ATTR_MODE) {
umode_t mode = attr->ia_mode;
vfsgid_t vfsgid = i_gid_into_vfsgid(mnt_userns, inode);
if (!vfsgid_in_group_p(vfsgid) &&
!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID))
mode &= ~S_ISGID;
inode->i_mode = mode;
}

and since the caller in the test is neither capable nor in the group of the
inode the S_ISGID bit is stripped.

But assume the file isn't suid then ATTR_KILL_SUID won't be raised which
has the consequence that neither the setgid nor the suid bits are stripped
even though it should be stripped because the inode isn't in the caller's
groups and the caller isn't privileged over the inode.

If overlayfs is in the mix things become a bit more complicated and the bug
shows up more clearly. When e.g., ovl_setattr() is hit from
ovl_fallocate()'s call to file_remove_privs() then ATTR_KILL_SUID and
ATTR_KILL_SGID might be raised but because the check in notify_change() is
questioning the ATTR_KILL_SGID flag again by requiring S_IXGRP for it to be
stripped the S_ISGID bit isn't removed even though it should be stripped:

sys_fallocate()
-> vfs_fallocate()
-> ovl_fallocate()
-> file_remove_privs()
-> dentry_needs_remove_privs()
-> should_remove_suid()
-> __remove_privs()
newattrs.ia_valid = ATTR_FORCE | kill;
-> notify_change()
-> ovl_setattr()
// TAKE ON MOUNTER'S CREDS
-> ovl_do_notify_change()
-> notify_change()
// GIVE UP MOUNTER'S CREDS
// TAKE ON MOUNTER'S CREDS
-> vfs_fallocate()
-> xfs_file_fallocate()
-> file_modified()
-> __file_remove_privs()
-> dentry_needs_remove_privs()
-> should_remove_suid()
-> __remove_privs()
newattrs.ia_valid = attr_force | kill;
-> notify_change()

The fix for all of this is to make file_remove_privs()'s
should_remove_suid() helper to perform the same checks as we already
require in setattr_prepare() and setattr_copy() and have notify_change()
not pointlessly requiring S_IXGRP again. It doesn't make any sense in the
first place because the caller must calculate the flags via
should_remove_suid() anyway which would raise ATTR_KILL_SGID.

While we're at it we move should_remove_suid() from inode.c to attr.c
where it belongs with the rest of the iattr helpers. Especially since it
returns ATTR_KILL_S{G,U}ID flags. We also rename it to
setattr_should_drop_suidgid() to better reflect that it indicates both
setuid and setgid bit removal and also that it returns attr flags.

Running xfstests with this doesn't report any regressions. We should really
try and use consistent checks.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

attr: add setattr_should_drop_sgid()

The current setgid stripping logic during write and ownership change
operations is inconsistent and strewn over multiple places. In order to
consolidate it and make more consistent we'll add a new helper
setattr_should_drop_sgid(). The function retains the old behavior where
we remove the S_ISGID bit unconditionally when S_IXGRP is set but also
when it isn't set and the caller is neither in the group of the inode
nor privileged over the inode.

We will use this helper both in write operation permission removal such
as file_remove_privs() as well as in ownership change operations.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

fs: move should_remove_suid()

Move the helper from inode.c to attr.c. This keeps the the core of the
set{g,u}id stripping logic in one place when we add follow-up changes.
It is the better place anyway, since should_remove_suid() returns
ATTR_KILL_S{G,U}ID flags.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

attr: add in_group_or_capable()

In setattr_{copy,prepare}() we need to perform the same permission
checks to determine whether we need to drop the setgid bit or not.
Instead of open-coding it twice add a simple helper the encapsulates the
logic. We will reuse this helpers to make dropping the setgid bit during
write operations more consistent in a follow up patch.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

vfs: Check the truncate maximum size in inode_newsize_ok()

If something manages to set the maximum file size to MAX_OFFSET+1, this
can cause the xfs and ext4 filesystems at least to become corrupt.

Ordinarily, the kernel protects against userspace trying this by
checking the value early in the truncate() and ftruncate() system calls
calls - but there are at least two places that this check is bypassed:

(1) Cachefiles will round up the EOF of the backing file to DIO block
size so as to allow DIO on the final block - but this might push
the offset negative. It then calls notify_change(), but this
inadvertently bypasses the checking. This can be triggered if
someone puts an 8EiB-1 file on a server for someone else to try and
access by, say, nfs.

(2) ksmbd doesn't check the value it is given in set_end_of_file_info()
and then calls vfs_truncate() directly - which also bypasses the
check.

In both cases, it is potentially possible for a network filesystem to
cause a disk filesystem to be corrupted: cachefiles in the client's
cache filesystem; ksmbd in the server's filesystem.

nfsd is okay as it checks the value, but we can then remove this check
too.

Fix this by adding a check to inode_newsize_ok(), as called from
setattr_prepare(), thereby catching the issue as filesystems set up to
perform the truncate with minimal opportunity for bypassing the new
check.

Fixes: 1f08c925e7a3 ("cachefiles: Implement backing file wrangling")
Fixes: f44158485826 ("cifsd: add file operations")
Signed-off-by: David Howells <dhowells@redhat.com>
Reported-by: Jeff Layton <jlayton@kernel.org>
Tested-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Cc: stable@kernel.org
Acked-by: Alexander Viro <viro@zeniv.linux.org.uk>
cc: Steve French <sfrench@samba.org>
cc: Hyunchul Lee <hyc.lee@gmail.com>
cc: Chuck Lever <chuck.lever@oracle.com>
cc: Dave Wysochanski <dwysocha@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

attr: fix kernel doc

When building kernel documentation new warnings were generated because
the name in the parameter documentation didn't match the parameter name.

Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

attr: port attribute changes to new types

Now that we introduced new infrastructure to increase the type safety
for filesystems supporting idmapped mounts port the first part of the
vfs over to them.

This ports the attribute changes codepaths to rely on the new better
helpers using a dedicated type.

Before this change we used to take a shortcut and place the actual
values that would be written to inode->i_{g,u}id into struct iattr. This
had the advantage that we moved idmappings mostly out of the picture
early on but it made reasoning about changes more difficult than it
should be.

The filesystem was never explicitly told that it dealt with an idmapped
mount. The transition to the value that needed to be stored in
inode->i_{g,u}id appeared way too early and increased the probability of
bugs in various codepaths.

We know place the same value in struct iattr no matter if this is an
idmapped mount or not. The vfs will only deal with type safe
vfs{g,u}id_t. This makes it massively safer to perform permission checks
as the type will tell us what checks we need to perform and what helpers
we need to use.

Fileystems raising FS_ALLOW_IDMAP can't simply write ia_vfs{g,u}id to
inode->i_{g,u}id since they are different types. Instead they need to
use the dedicated vfs{g,u}id_to_k{g,u}id() helpers that map the
vfs{g,u}id into the filesystem.

The other nice effect is that filesystems like overlayfs don't need to
care about idmappings explicitly anymore and can simply set up struct
iattr accordingly directly.

Link: https://lore.kernel.org/lkml/CAHk-=win6+ahs1EwLkcq8apqLi_1wXFWbrPf340zYEhObpz4jA@mail.gmail.com [1]
Link: https://lore.kernel.org/r/20220621141454.2914719-9-brauner@kernel.org
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

security: pass down mount idmapping to setattr hook

Before this change we used to take a shortcut and place the actual
values that would be written to inode->i_{g,u}id into struct iattr. This
had the advantage that we moved idmappings mostly out of the picture
early on but it made reasoning about changes more difficult than it
should be.

The filesystem was never explicitly told that it dealt with an idmapped
mount. The transition to the value that needed to be stored in
inode->i_{g,u}id appeared way too early and increased the probability of
bugs in various codepaths.

We know place the same value in struct iattr no matter if this is an
idmapped mount or not. The vfs will only deal with type safe
vfs{g,u}id_t. This makes it massively safer to perform permission checks
as the type will tell us what checks we need to perform and what helpers
we need to use.

Adapt the security_inode_setattr() helper to pass down the mount's
idmapping to account for that change.

Link: https://lore.kernel.org/r/20220621141454.2914719-8-brauner@kernel.org
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

fs: port to iattr ownership update helpers

Earlier we introduced new helpers to abstract ownership update and
remove code duplication. This converts all filesystems supporting
idmapped mounts to make use of these new helpers.

For now we always pass the initial idmapping which makes the idmapping
functions these helpers call nops.

This is done because we currently always pass the actual value to be
written to i_{g,u}id via struct iattr. While this allowed us to treat
the {g,u}id values in struct iattr as values that can be directly
written to inode->i_{g,u}id it also increases the potential for
confusion for filesystems.

Now that we are have dedicated types to prevent this confusion we will
ultimately only map the value from the idmapped mount into a filesystem
value that can be written to inode->i_{g,u}id when the filesystem
actually updates the inode. So pass down the initial idmapping until we
finished that conversion at which point we pass down the mount's
idmapping.

No functional changes intended.

Link: https://lore.kernel.org/r/20220621141454.2914719-6-brauner@kernel.org
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

fs: account for group membership

When calling setattr_prepare() to determine the validity of the
attributes the ia_{g,u}id fields contain the value that will be written
to inode->i_{g,u}id. This is exactly the same for idmapped and
non-idmapped mounts and allows callers to pass in the values they want
to see written to inode->i_{g,u}id.

When group ownership is changed a caller whose fsuid owns the inode can
change the group of the inode to any group they are a member of. When
searching through the caller's groups we need to use the gid mapped
according to the idmapped mount otherwise we will fail to change
ownership for unprivileged users.

Consider a caller running with fsuid and fsgid 1000 using an idmapped
mount that maps id 65534 to 1000 and 65535 to 1001. Consequently, a file
owned by 65534:65535 in the filesystem will be owned by 1000:1001 in the
idmapped mount.

The caller now requests the gid of the file to be changed to 1000 going
through the idmapped mount. In the vfs we will immediately map the
requested gid to the value that will need to be written to inode->i_gid
and place it in attr->ia_gid. Since this idmapped mount maps 65534 to
1000 we place 65534 in attr->ia_gid.

When we check whether the caller is allowed to change group ownership we
first validate that their fsuid matches the inode's uid. The
inode->i_uid is 65534 which is mapped to uid 1000 in the idmapped mount.
Since the caller's fsuid is 1000 we pass the check.

We now check whether the caller is allowed to change inode->i_gid to the
requested gid by calling in_group_p(). This will compare the passed in
gid to the caller's fsgid and search the caller's additional groups.

Since we're dealing with an idmapped mount we need to pass in the gid
mapped according to the idmapped mount. This is akin to checking whether
a caller is privileged over the future group the inode is owned by. And
that needs to take the idmapped mount into account. Note, all helpers
are nops without idmapped mounts.

New regression test sent to xfstests.

Link: https://github.com/lxc/lxd/issues/10537
Link: https://lore.kernel.org/r/20220613111517.2186646-1-brauner@kernel.org
Fixes: 2f221d6f7b88 ("attr: handle idmapped mounts")
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@vger.kernel.org # 5.15+
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

fs: handle circular mappings correctly

When calling setattr_prepare() to determine the validity of the attributes the
ia_{g,u}id fields contain the value that will be written to inode->i_{g,u}id.
When the {g,u}id attribute of the file isn't altered and the caller's fs{g,u}id
matches the current {g,u}id attribute the attribute change is allowed.

The value in ia_{g,u}id does already account for idmapped mounts and will have
taken the relevant idmapping into account. So in order to verify that the
{g,u}id attribute isn't changed we simple need to compare the ia_{g,u}id value
against the inode's i_{g,u}id value.

This only has any meaning for idmapped mounts as idmapping helpers are
idempotent without them. And for idmapped mounts this really only has a meaning
when circular idmappings are used, i.e. mappings where e.g. id 1000 is mapped
to id 1001 and id 1001 is mapped to id 1000. Such ciruclar mappings can e.g. be
useful when sharing the same home directory between multiple users at the same
time.

As an example consider a directory with two files: /source/file1 owned by
{g,u}id 1000 and /source/file2 owned by {g,u}id 1001. Assume we create an
idmapped mount at /target with an idmapping that maps files owned by {g,u}id
1000 to being owned by {g,u}id 1001 and files owned by {g,u}id 1001 to being
owned by {g,u}id 1000. In effect, the idmapped mount at /target switches the
ownership of /source/file1 and source/file2, i.e. /target/file1 will be owned
by {g,u}id 1001 and /target/file2 will be owned by {g,u}id 1000.

This means that a user with fs{g,u}id 1000 must be allowed to setattr
/target/file2 from {g,u}id 1000 to {g,u}id 1000. Similar, a user with fs{g,u}id
1001 must be allowed to setattr /target/file1 from {g,u}id 1001 to {g,u}id
1001. Conversely, a user with fs{g,u}id 1000 must fail to setattr /target/file1
from {g,u}id 1001 to {g,u}id 1000. And a user with fs{g,u}id 1001 must fail to
setattr /target/file2 from {g,u}id 1000 to {g,u}id 1000. Both cases must fail
with EPERM for non-capable callers.

Before this patch we could end up denying legitimate attribute changes and
allowing invalid attribute changes when circular mappings are used. To even get
into this situation the caller must've been privileged both to create that
mapping and to create that idmapped mount.

This hasn't been seen in the wild anywhere but came up when expanding the
testsuite during work on a series of hardening patches. All idmapped fstests
pass without any regressions and we add new tests to verify the behavior of
circular mappings.

Link: https://lore.kernel.org/r/20211109145713.1868404-1-brauner@kernel.org
Fixes: 2f221d6f7b88 ("attr: handle idmapped mounts")
Cc: Seth Forshee <seth.forshee@digitalocean.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@vger.kernel.org
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

fs: Move notify_change permission checks into may_setattr

Move the permission checks in notify_change into a separate function to
make them available to filesystems.

When notify_change is called, the vfs performs those checks before
calling into iop->setattr. However, a filesystem like gfs2 can only
lock and revalidate the inode inside ->setattr, and it must then repeat
those checks to err on the safe side.

It would be nice to get rid of the double checking, but moving the
permission check into iop->setattr altogether isn't really an option.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

ima: handle idmapped mounts

IMA does sometimes access the inode's i_uid and compares it against the
rules' fowner. Enable IMA to handle idmapped mounts by passing down the
mount's user namespace. We simply make use of the helpers we introduced
before. If the initial user namespace is passed nothing changes so
non-idmapped mounts will see identical behavior as before.

Link: https://lore.kernel.org/r/20210121131959.646623-27-christian.brauner@ubuntu.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

fs: make helpers idmap mount aware

Extend some inode methods with an additional user namespace argument. A
filesystem that is aware of idmapped mounts will receive the user
namespace the mount has been marked with. This can be used for
additional permission checking and also to enable filesystems to
translate between uids and gids if they need to. We have implemented all
relevant helpers in earlier patches.

As requested we simply extend the exisiting inode method instead of
introducing new ones. This is a little more code churn but it's mostly
mechanical and doesnt't leave us with additional inode methods.

Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

commoncap: handle idmapped mounts

When interacting with user namespace and non-user namespace aware
filesystem capabilities the vfs will perform various security checks to
determine whether or not the filesystem capabilities can be used by the
caller, whether they need to be removed and so on. The main
infrastructure for this resides in the capability codepaths but they are
called through the LSM security infrastructure even though they are not
technically an LSM or optional. This extends the existing security hooks
security_inode_removexattr(), security_inode_killpriv(),
security_inode_getsecurity() to pass down the mount's user namespace and
makes them aware of idmapped mounts.

In order to actually get filesystem capabilities from disk the
capability infrastructure exposes the get_vfs_caps_from_disk() helper.
For user namespace aware filesystem capabilities a root uid is stored
alongside the capabilities.

In order to determine whether the caller can make use of the filesystem
capability or whether it needs to be ignored it is translated according
to the superblock's user namespace. If it can be translated to uid 0
according to that id mapping the caller can use the filesystem
capabilities stored on disk. If we are accessing the inode that holds
the filesystem capabilities through an idmapped mount we map the root
uid according to the mount's user namespace. Afterwards the checks are
identical to non-idmapped mounts: reading filesystem caps from disk
enforces that the root uid associated with the filesystem capability
must have a mapping in the superblock's user namespace and that the
caller is either in the same user namespace or is a descendant of the
superblock's user namespace. For filesystems that are mountable inside
user namespace the caller can just mount the filesystem and won't
usually need to idmap it. If they do want to idmap it they can create an
idmapped mount and mark it with a user namespace they created and which
is thus a descendant of s_user_ns. For filesystems that are not
mountable inside user namespaces the descendant rule is trivially true
because the s_user_ns will be the initial user namespace.

If the initial user namespace is passed nothing changes so non-idmapped
mounts will see identical behavior as before.

Link: https://lore.kernel.org/r/20210121131959.646623-11-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

attr: handle idmapped mounts

When file attributes are changed most filesystems rely on the
setattr_prepare(), setattr_copy(), and notify_change() helpers for
initialization and permission checking. Let them handle idmapped mounts.
If the inode is accessed through an idmapped mount map it into the
mount's user namespace. Afterwards the checks are identical to
non-idmapped mounts. If the initial user namespace is passed nothing
changes so non-idmapped mounts will see identical behavior as before.

Helpers that perform checks on the ia_uid and ia_gid fields in struct
iattr assume that ia_uid and ia_gid are intended values and have already
been mapped correctly at the userspace-kernelspace boundary as we
already do today. If the initial user namespace is passed nothing
changes so non-idmapped mounts will see identical behavior as before.

Link: https://lore.kernel.org/r/20210121131959.646623-8-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

inode: make init and permission helpers idmapped mount aware

The inode_owner_or_capable() helper determines whether the caller is the
owner of the inode or is capable with respect to that inode. Allow it to
handle idmapped mounts. If the inode is accessed through an idmapped
mount it according to the mount's user namespace. Afterwards the checks
are identical to non-idmapped mounts. If the initial user namespace is
passed nothing changes so non-idmapped mounts will see identical
behavior as before.

Similarly, allow the inode_init_owner() helper to handle idmapped
mounts. It initializes a new inode on idmapped mounts by mapping the
fsuid and fsgid of the caller from the mount's user namespace. If the
initial user namespace is passed nothing changes so non-idmapped mounts
will see identical behavior as before.

Link: https://lore.kernel.org/r/20210121131959.646623-7-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

namei: make permission helpers idmapped mount aware

The two helpers inode_permission() and generic_permission() are used by
the vfs to perform basic permission checking by verifying that the
caller is privileged over an inode. In order to handle idmapped mounts
we extend the two helpers with an additional user namespace argument.
On idmapped mounts the two helpers will make sure to map the inode
according to the mount's user namespace and then peform identical
permission checks to inode_permission() and generic_permission(). If the
initial user namespace is passed nothing changes so non-idmapped mounts
will see identical behavior as before.

Link: https://lore.kernel.org/r/20210121131959.646623-6-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

capability: handle idmapped mounts

In order to determine whether a caller holds privilege over a given
inode the capability framework exposes the two helpers
privileged_wrt_inode_uidgid() and capable_wrt_inode_uidgid(). The former
verifies that the inode has a mapping in the caller's user namespace and
the latter additionally verifies that the caller has the requested
capability in their current user namespace.
If the inode is accessed through an idmapped mount map it into the
mount's user namespace. Afterwards the checks are identical to
non-idmapped inodes. If the initial user namespace is passed all
operations are a nop so non-idmapped mounts will not see a change in
behavior.

Link: https://lore.kernel.org/r/20210121131959.646623-5-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

utimes: Clamp the timestamps in notify_change()

Push clamping timestamps into notify_change(), so in-kernel
callers like nfsd and overlayfs will get similar timestamp
set behavior as utimes.

AV: get rid of clamping in ->setattr() instances; we don't need
to bother with that there, with notify_change() doing normalization
in all cases now (it already did for implicit case, since current_time()
clamps).

Suggested-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 42e729b9ddbb ("utimes: Clamp the timestamps before update")
Cc: stable@vger.kernel.org # v5.4
Cc: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

timestamp_truncate: Replace users of timespec64_trunc

Update the inode timestamp updates to use timestamp_truncate()
instead of timespec64_trunc().

The change was mostly generated by the following coccinelle
script.

virtual context
virtual patch

@r1 depends on patch forall@
struct inode *inode;
identifier i_xtime =~ "^i_[acm]time$";
expression e;
@@

inode->i_xtime =
- timespec64_trunc(
+ timestamp_truncate(
...,
- e);
+ inode);

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Jeff Layton <jlayton@kernel.org>
Cc: adrian.hunter@intel.com
Cc: dedekind1@gmail.com
Cc: gregkh@linuxfoundation.org
Cc: hch@lst.de
Cc: jaegeuk@kernel.org
Cc: jlbec@evilplan.org
Cc: richard@nod.at
Cc: tj@kernel.org
Cc: yuchao0@huawei.com
Cc: linux-f2fs-devel@lists.sourceforge.net
Cc: linux-ntfs-dev@lists.sourceforge.net
Cc: linux-mtd@lists.infradead.org

fs: Fix attr.c kernel-doc

A couple of minor warnings.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

vfs: change inode times to use struct timespec64

struct timespec is not y2038 safe. Transition vfs to use
y2038 safe struct timespec64 instead.

The change was made with the help of the following cocinelle
script. This catches about 80% of the changes.
All the header file and logic changes are included in the
first 5 rules. The rest are trivial substitutions.
I avoid changing any of the function signatures or any other
filesystem specific data structures to keep the patch simple
for review.

The script can be a little shorter by combining different cases.
But, this version was sufficient for my usecase.

virtual patch

@ depends on patch @
identifier now;
@@
- struct timespec
+ struct timespec64
current_time ( ... )
{
- struct timespec now = current_kernel_time();
+ struct timespec64 now = current_kernel_time64();
...
- return timespec_trunc(
+ return timespec64_trunc(
... );
}

@ depends on patch @
identifier xtime;
@@
struct \( iattr \| inode \| kstat \) {
...
- struct timespec xtime;
+ struct timespec64 xtime;
...
}

@ depends on patch @
identifier t;
@@
struct inode_operations {
...
int (*update_time) (...,
- struct timespec t,
+ struct timespec64 t,
...);
...
}

@ depends on patch @
identifier t;
identifier fn_update_time =~ "update_time$";
@@
fn_update_time (...,
- struct timespec *t,
+ struct timespec64 *t,
...) { ... }

@ depends on patch @
identifier t;
@@
lease_get_mtime( ... ,
- struct timespec *t
+ struct timespec64 *t
) { ... }

@te depends on patch forall@
identifier ts;
local idexpression struct inode *inode_node;
identifier i_xtime =~ "^i_[acm]time$";
identifier ia_xtime =~ "^ia_[acm]time$";
identifier fn_update_time =~ "update_time$";
identifier fn;
expression e, E3;
local idexpression struct inode *node1;
local idexpression struct inode *node2;
local idexpression struct iattr *attr1;
local idexpression struct iattr *attr2;
local idexpression struct iattr attr;
identifier i_xtime1 =~ "^i_[acm]time$";
identifier i_xtime2 =~ "^i_[acm]time$";
identifier ia_xtime1 =~ "^ia_[acm]time$";
identifier ia_xtime2 =~ "^ia_[acm]time$";
@@
(
(
- struct timespec ts;
+ struct timespec64 ts;
|
- struct timespec ts = current_time(inode_node);
+ struct timespec64 ts = current_time(inode_node);
)

<+... when != ts
(
- timespec_equal(&inode_node->i_xtime, &ts)
+ timespec64_equal(&inode_node->i_xtime, &ts)
|
- timespec_equal(&ts, &inode_node->i_xtime)
+ timespec64_equal(&ts, &inode_node->i_xtime)
|
- timespec_compare(&inode_node->i_xtime, &ts)
+ timespec64_compare(&inode_node->i_xtime, &ts)
|
- timespec_compare(&ts, &inode_node->i_xtime)
+ timespec64_compare(&ts, &inode_node->i_xtime)
|
ts = current_time(e)
|
fn_update_time(..., &ts,...)
|
inode_node->i_xtime = ts
|
node1->i_xtime = ts
|
ts = inode_node->i_xtime
|
<+... attr1->ia_xtime ...+> = ts
|
ts = attr1->ia_xtime
|
ts.tv_sec
|
ts.tv_nsec
|
btrfs_set_stack_timespec_sec(..., ts.tv_sec)
|
btrfs_set_stack_timespec_nsec(..., ts.tv_nsec)
|
- ts = timespec64_to_timespec(
+ ts =
...
-)
|
- ts = ktime_to_timespec(
+ ts = ktime_to_timespec64(
...)
|
- ts = E3
+ ts = timespec_to_timespec64(E3)
|
- ktime_get_real_ts(&ts)
+ ktime_get_real_ts64(&ts)
|
fn(...,
- ts
+ timespec64_to_timespec(ts)
,...)
)
...+>
(
<... when != ts
- return ts;
+ return timespec64_to_timespec(ts);
...>
)
|
- timespec_equal(&node1->i_xtime1, &node2->i_xtime2)
+ timespec64_equal(&node1->i_xtime2, &node2->i_xtime2)
|
- timespec_equal(&node1->i_xtime1, &attr2->ia_xtime2)
+ timespec64_equal(&node1->i_xtime2, &attr2->ia_xtime2)
|
- timespec_compare(&node1->i_xtime1, &node2->i_xtime2)
+ timespec64_compare(&node1->i_xtime1, &node2->i_xtime2)
|
node1->i_xtime1 =
- timespec_trunc(attr1->ia_xtime1,
+ timespec64_trunc(attr1->ia_xtime1,
...)
|
- attr1->ia_xtime1 = timespec_trunc(attr2->ia_xtime2,
+ attr1->ia_xtime1 = timespec64_trunc(attr2->ia_xtime2,
...)
|
- ktime_get_real_ts(&attr1->ia_xtime1)
+ ktime_get_real_ts64(&attr1->ia_xtime1)
|
- ktime_get_real_ts(&attr.ia_xtime1)
+ ktime_get_real_ts64(&attr.ia_xtime1)
)

@ depends on patch @
struct inode *node;
struct iattr *attr;
identifier fn;
identifier i_xtime =~ "^i_[acm]time$";
identifier ia_xtime =~ "^ia_[acm]time$";
expression e;
@@
(
- fn(node->i_xtime);
+ fn(timespec64_to_timespec(node->i_xtime));
|
fn(...,
- node->i_xtime);
+ timespec64_to_timespec(node->i_xtime));
|
- e = fn(attr->ia_xtime);
+ e = fn(timespec64_to_timespec(attr->ia_xtime));
)

@ depends on patch forall @
struct inode *node;
struct iattr *attr;
identifier i_xtime =~ "^i_[acm]time$";
identifier ia_xtime =~ "^ia_[acm]time$";
identifier fn;
@@
{
+ struct timespec ts;
<+...
(
+ ts = timespec64_to_timespec(node->i_xtime);
fn (...,
- &node->i_xtime,
+ &ts,
...);
|
+ ts = timespec64_to_timespec(attr->ia_xtime);
fn (...,
- &attr->ia_xtime,
+ &ts,
...);
)
...+>
}

@ depends on patch forall @
struct inode *node;
struct iattr *attr;
struct kstat *stat;
identifier ia_xtime =~ "^ia_[acm]time$";
identifier i_xtime =~ "^i_[acm]time$";
identifier xtime =~ "^[acm]time$";
identifier fn, ret;
@@
{
+ struct timespec ts;
<+...
(
+ ts = timespec64_to_timespec(node->i_xtime);
ret = fn (...,
- &node->i_xtime,
+ &ts,
...);
|
+ ts = timespec64_to_timespec(node->i_xtime);
ret = fn (...,
- &node->i_xtime);
+ &ts);
|
+ ts = timespec64_to_timespec(attr->ia_xtime);
ret = fn (...,
- &attr->ia_xtime,
+ &ts,
...);
|
+ ts = timespec64_to_timespec(attr->ia_xtime);
ret = fn (...,
- &attr->ia_xtime);
+ &ts);
|
+ ts = timespec64_to_timespec(stat->xtime);
ret = fn (...,
- &stat->xtime);
+ &ts);
)
...+>
}

@ depends on patch @
struct inode *node;
struct inode *node2;
identifier i_xtime1 =~ "^i_[acm]time$";
identifier i_xtime2 =~ "^i_[acm]time$";
identifier i_xtime3 =~ "^i_[acm]time$";
struct iattr *attrp;
struct iattr *attrp2;
struct iattr attr ;
identifier ia_xtime1 =~ "^ia_[acm]time$";
identifier ia_xtime2 =~ "^ia_[acm]time$";
struct kstat *stat;
struct kstat stat1;
struct timespec64 ts;
identifier xtime =~ "^[acmb]time$";
expression e;
@@
(
( node->i_xtime2 \| attrp->ia_xtime2 \| attr.ia_xtime2 \) = node->i_xtime1 ;
|
node->i_xtime2 = \( node2->i_xtime1 \| timespec64_trunc(...) \);
|
node->i_xtime2 = node->i_xtime1 = node->i_xtime3 = \(ts \| current_time(...) \);
|
node->i_xtime1 = node->i_xtime3 = \(ts \| current_time(...) \);
|
stat->xtime = node2->i_xtime1;
|
stat1.xtime = node2->i_xtime1;
|
( node->i_xtime2 \| attrp->ia_xtime2 \) = attrp->ia_xtime1 ;
|
( attrp->ia_xtime1 \| attr.ia_xtime1 \) = attrp2->ia_xtime2;
|
- e = node->i_xtime1;
+ e = timespec64_to_timespec( node->i_xtime1 );
|
- e = attrp->ia_xtime1;
+ e = timespec64_to_timespec( attrp->ia_xtime1 );
|
node->i_xtime1 = current_time(...);
|
node->i_xtime2 = node->i_xtime1 = node->i_xtime3 =
- e;
+ timespec_to_timespec64(e);
|
node->i_xtime1 = node->i_xtime3 =
- e;
+ timespec_to_timespec64(e);
|
- node->i_xtime1 = e;
+ node->i_xtime1 = timespec_to_timespec64(e);
)

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: <anton@tuxera.com>
Cc: <balbi@kernel.org>
Cc: <bfields@fieldses.org>
Cc: <darrick.wong@oracle.com>
Cc: <dhowells@redhat.com>
Cc: <dsterba@suse.com>
Cc: <dwmw2@infradead.org>
Cc: <hch@lst.de>
Cc: <hirofumi@mail.parknet.co.jp>
Cc: <hubcap@omnibond.com>
Cc: <jack@suse.com>
Cc: <jaegeuk@kernel.org>
Cc: <jaharkes@cs.cmu.edu>
Cc: <jslaby@suse.com>
Cc: <keescook@chromium.org>
Cc: <mark@fasheh.com>
Cc: <miklos@szeredi.hu>
Cc: <nico@linaro.org>
Cc: <reiserfs-devel@vger.kernel.org>
Cc: <richard@nod.at>
Cc: <sage@redhat.com>
Cc: <sfrench@samba.org>
Cc: <swhiteho@redhat.com>
Cc: <tj@kernel.org>
Cc: <trond.myklebust@primarydata.com>
Cc: <tytso@mit.edu>
Cc: <viro@zeniv.linux.org.uk>

fs: Allow superblock owner to replace invalid owners of inodes

Allow users with CAP_SYS_CHOWN over the superblock of a filesystem to
chown files when inode owner is invalid. Ordinarily the
capable_wrt_inode_uidgid check is sufficient to allow access to files
but when the underlying filesystem has uids or gids that don't map to
the current user namespace it is not enough, so the chown permission
checks need to be extended to allow this case.

Calling chown on filesystem nodes whose uid or gid don't map is
necessary if those nodes are going to be modified as writing back
inodes which contain uids or gids that don't map is likely to cause
filesystem corruption of the uid or gid fields.

Once chown has been called the existing capable_wrt_inode_uidgid
checks are sufficient to allow the owner of a superblock to do anything
the global root user can do with an appropriate set of capabilities.

An ordinary filesystem mountable by a userns root will limit all uids
and gids in s_user_ns or the INVALID_UID and INVALID_GID to flag all
others. So having this added permission limited to just INVALID_UID
and INVALID_GID is sufficient to handle every case on an ordinary filesystem.

Of the virtual filesystems at least proc is known to set s_user_ns to
something other than &init_user_ns, while at the same time presenting
some files owned by GLOBAL_ROOT_UID. Those files the mounter of proc
in a user namespace should not be able to chown to get access to.
Limiting the relaxation in permission to just the minimum of allowing
changing INVALID_UID and INVALID_GID prevents problems with cases like
that.

The original version of this patch was written by: Seth Forshee. I
have rewritten and rethought this patch enough so it's really not the
same thing (certainly it needs a different description), but he
deserves credit for getting out there and getting the conversation
started, and finding the potential gotcha's and putting up with my
semi-paranoid feedback.

Inspired-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

sched/headers: Prepare for new header dependencies before moving code to <linux/sched/signal.h>

We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/signal.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

fs: Replace current_fs_time() with current_time()

current_fs_time() uses struct super_block* as an argument.
As per Linus's suggestion, this is changed to take struct
inode* as a parameter instead. This is because the function
is primarily meant for vfs inode timestamps.
Also the function was renamed as per Arnd's suggestion.

Change all calls to current_fs_time() to use the new
current_time() function instead. current_fs_time() will be
deleted.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs: Avoid premature clearing of capabilities

Currently, notify_change() clears capabilities or IMA attributes by
calling security_inode_killpriv() before calling into ->setattr. Thus it
happens before any other permission checks in inode_change_ok() and user
is thus allowed to trigger clearing of capabilities or IMA attributes
for any file he can look up e.g. by calling chown for that file. This is
unexpected and can lead to user DoSing a system.

Fix the problem by calling security_inode_killpriv() at the end of
inode_change_ok() instead of from notify_change(). At that moment we are
sure user has permissions to do the requested change.

References: CVE-2015-1350
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>

fs: Give dentry to inode_change_ok() instead of inode

inode_change_ok() will be resposible for clearing capabilities and IMA
extended attributes and as such will need dentry. Give it as an argument
to inode_change_ok() instead of an inode. Also rename inode_change_ok()
to setattr_prepare() to better relect that it does also some
modifications in addition to checks.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>

vfs: move permission checking into notify_change() for utimes(NULL)

This fixes a bug where the permission was not properly checked in
overlayfs. The testcase is ltp/utimensat01.

It is also cleaner and safer to do the permission checking in the vfs
helper instead of the caller.

This patch introduces an additional ia_valid flag ATTR_TOUCH (since
touch(1) is the most obvious user of utimes(NULL)) that is passed into
notify_change whenever the conditions for this special permission checking
mode are met.

Reported-by: Aihua Zhang <zhangaihua1@huawei.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Tested-by: Aihua Zhang <zhangaihua1@huawei.com>
Cc: <stable@vger.kernel.org> # v3.18+

vfs: Don't modify inodes with a uid or gid unknown to the vfs

When a filesystem outside of init_user_ns is mounted it could have
uids and gids stored in it that do not map to init_user_ns.

The plan is to allow those filesystems to set i_uid to INVALID_UID and
i_gid to INVALID_GID for unmapped uids and gids and then to handle
that strange case in the vfs to ensure there is consistent robust
handling of the weirdness.

Upon a careful review of the vfs and filesystems about the only case
where there is any possibility of confusion or trouble is when the
inode is written back to disk. In that case filesystems typically
read the inode->i_uid and inode->i_gid and write them to disk even
when just an inode timestamp is being updated.

Which leads to a rule that is very simple to implement and understand
inodes whose i_uid or i_gid is not valid may not be written.

In dealing with access times this means treat those inodes as if the
inode flag S_NOATIME was set. Reads of the inodes appear safe and
useful, but any write or modification is disallowed. The only inode
write that is allowed is a chown that sets the uid and gid on the
inode to valid values. After such a chown the inode is normal and may
be treated as such.

Denying all writes to inodes with uids or gids unknown to the vfs also
prevents several oddball cases where corruption would have occurred
because the vfs does not have complete information.

One problem case that is prevented is attempting to use the gid of a
directory for new inodes where the directories sgid bit is set but the
directories gid is not mapped.

Another problem case avoided is attempting to update the evm hash
after setxattr, removexattr, and setattr. As the evm hash includeds
the inode->i_uid or inode->i_gid not knowning the uid or gid prevents
a correct evm hash from being computed. evm hash verification also
fails when i_uid or i_gid is unknown but that is essentially harmless
as it does not cause filesystem corruption.

Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

fs: Refuse uid/gid changes which don't map into s_user_ns

Add checks to notify_change to verify that uid and gid changes
will map into the superblock's user namespace. If they do not
fail with -EOVERFLOW.

This is mandatory so that fileystems don't have to even think
of dealing with ia_uid and ia_gid that

--EWB Moved the test from inode_change_ok to notify_change

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

wrappers for ->i_mutex access

parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).

Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs,userns: Change inode_capable to capable_wrt_inode_uidgid

The kernel has no concept of capabilities with respect to inodes; inodes
exist independently of namespaces. For example, inode_capable(inode,
CAP_LINUX_IMMUTABLE) would be nonsense.

This patch changes inode_capable to check for uid and gid mappings and
renames it to capable_wrt_inode_uidgid, which should make it more
obvious what it does.

Fixes CVE-2014-4014.

Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Serge Hallyn <serge.hallyn@ubuntu.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: stable@vger.kernel.org
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs: fix iversion handling

Currently notify_change directly updates i_version for size updates,
which not only is counter to how all other fields are updated through
struct iattr, but also breaks XFS, which need inode updates to happen
under its own lock, and synchronized to the structure that gets written
to the log.

Remove the update in the common code, and it to btrfs and ext4,
XFS already does a proper updaste internally and currently gets a
double update with the existing code.

IMHO this is 3.13 and -stable material and should go in through the XFS
tree.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Acked-by: Jan Kara <jack@suse.cz>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

locks: break delegations on any attribute modification

NFSv4 uses leases to guarantee that clients can cache metadata as well
as data.

Cc: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Cc: David Howells <dhowells@redhat.com>
Cc: Tyler Hicks <tyhicks@canonical.com>
Cc: Dustin Kirkland <dustin.kirkland@gazzang.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

userns: Allow chown and setgid preservation

- Allow chown if CAP_CHOWN is present in the current user namespace
and the uid of the inode maps into the current user namespace, and
the destination uid or gid maps into the current user namespace.

- Allow perserving setgid when changing an inode if CAP_FSETID is
present in the current user namespace and the owner of the file has
a mapping into the current user namespace.

Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

ima: add inode_post_setattr call

Changing an inode's metadata may result in our not needing to appraise
the file. In such cases, we must remove 'security.ima'.

Changelog v1:
- use ima_inode_post_setattr() stub function, if IMA_APPRAISE not configured

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>

notify_change(): check that i_mutex is held

Cc: Djalal Harouni <tixxdz@opendz.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

vfs: increment iversion when a file is truncated

When a file is truncated with truncate()/ftruncate() and then closed,
iversion is not updated. This patch uses ATTR_SIZE flag as an indication
to increment iversion.

Mimi said:

On fput(), i_version is used to detect and flag files that have changed
and need to be re-measured in the IMA measurement policy. When a file
is truncated with truncate()/ftruncate() and then closed, i_version is
not updated. As a result, although the file has changed, it will not be
re-measured and added to the IMA measurement list on subsequent access.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Acked-by: Mimi Zohar <zohar@us.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

userns: Use uid_eq gid_eq helpers when comparing kuids and kgids in the vfs

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

fs: reduce the use of module.h wherever possible

For files only using THIS_MODULE and/or EXPORT_SYMBOL, map
them onto including export.h -- or if the file isn't even
using those, then just delete the include. Fix up any implicit
include dependencies that were being masked by module.h along
the way.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

switch is_sxid() to umode_t

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs: move inode_dio_wait calls into ->setattr

Let filesystems handle waiting for direct I/O requests themselves instead
of doing it beforehand. This means filesystem-specific locks to prevent
new dio referenes from appearing can be held. This is important to allow
generalizing i_dio_count to non-DIO_LOCKING filesystems.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs: kill i_alloc_sem

i_alloc_sem is a rather special rw_semaphore. It's the last one that may
be released by a non-owner, and it's write side is always mirrored by
real exclusion. It's intended use it to wait for all pending direct I/O
requests to finish before starting a truncate.

Replace it with a hand-grown construct:

- exclusion for truncates is already guaranteed by i_mutex, so it can
simply fall way
- the reader side is replaced by an i_dio_count member in struct inode
that counts the number of pending direct I/O requests. Truncate can't
proceed as long as it's non-zero
- when i_dio_count reaches non-zero we wake up a pending truncate using
wake_up_bit on a new bit in i_flags
- new references to i_dio_count can't appear while we are waiting for
it to read zero because the direct I/O count always needs i_mutex
(or an equivalent like XFS's i_iolock) for starting a new operation.

This scheme is much simpler, and saves the space of a spinlock_t and a
struct list_head in struct inode (typically 160 bits on a non-debug 64-bit
system).

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

evm: imbed evm_inode_post_setattr

Changing the inode's metadata may require the 'security.evm' extended
attribute to be re-calculated and updated.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com>

Cache xattr security drop check for write v2

Some recent benchmarking on btrfs showed that a major scaling bottleneck
on large systems on btrfs is currently the xattr lookup on every write.

Why xattr lookup on every write I hear you ask?

write wants to drop suid and security related xattrs that could set o
capabilities for executables. To do that it currently looks up
security.capability on EVERY write (even for non executables) to decide
whether to drop it or not.

In btrfs this causes an additional tree walk, hitting some per file system
locks and quite bad scalability. In a simple read workload on a 8S
system I saw over 90% CPU time in spinlocks related to that.

Chris Mason tells me this is also a problem in ext4, where it hits
the global mbcache lock.

This patch adds a simple per inode to avoid this problem. We only
do the lookup once per file and then if there is no xattr cache
the decision. All xattr changes clear the flag.

I also used the same flag to avoid the suid check, although
that one is pretty cheap.

A file system can also set this flag when it creates the inode,
if it has a cheap way to do so. This is done for some common file systems
in followon patches.

With this patch a major part of the lock contention disappears
for btrfs. Some testing on smaller systems didn't show significant
performance changes, but at least it helps the larger systems
and is generally more efficient.

v2: Rename is_sgid. add file system helper.
Cc: chris.mason@oracle.com
Cc: josef@redhat.com
Cc: viro@zeniv.linux.org.uk
Cc: agruen@linbit.com
Cc: Serge E. Hallyn <serue@us.ibm.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>

userns: rename is_owner_or_cap to inode_owner_or_capable

And give it a kernel-doc comment.

[akpm@linux-foundation.org: btrfs changed in linux-next]
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Daniel Lezcano <daniel.lezcano@free.fr>
Acked-by: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

check ATTR_SIZE contraints in inode_change_ok

Make sure we check the truncate constraints early on in ->setattr by adding
those checks to inode_change_ok. Also clean up and document inode_change_ok
to make this obvious.

As a fallout we don't have to call inode_newsize_ok from simple_setsize and
simplify it down to a truncate_setsize which doesn't return an error. This
simplifies a lot of setattr implementations and means we use truncate_setsize
almost everywhere. Get rid of fat_setsize now that it's trivial and mark
ext2_setsize static to make the calling convention obvious.

Keep the inode_newsize_ok in vmtruncate for now as all callers need an
audit for its removal anyway.

Note: setattr code in ecryptfs doesn't call inode_change_ok at all and
needs a deeper audit, but that is left for later.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

remove inode_setattr

Replace inode_setattr with opencoded variants of it in all callers. This
moves the remaining call to vmtruncate into the filesystem methods where it
can be replaced with the proper truncate sequence.

In a few cases it was obvious that we would never end up calling vmtruncate
so it was left out in the opencoded variant:

spufs: explicitly checks for ATTR_SIZE earlier
btrfs,hugetlbfs,logfs,dlmfs: explicitly clears ATTR_SIZE earlier
ufs: contains an opencoded simple_seattr + truncate that sets the filesize just above

In addition to that ncpfs called inode_setattr with handcrafted iattrs,
which allowed to trim down the opencoded variant.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

default to simple_setattr

With the new truncate sequence every filesystem that wants to support file
size changes on disk needs to implement its own ->setattr. So instead
of calling inode_setattr which supports size changes call into a simple
method that doesn't support this. simple_setattr is almost what we
want except that it does not mark the inode dirty after changes. Given
that marking the inode dirty is a no-op for the simple in-memory filesystems
that use simple_setattr currently just add the mark_inode_dirty call.

Also add a WARN_ON for the presence of a truncate method to simple_setattr
to catch new instances of it during the transition period.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

rename generic_setattr

Despite its name it's now a generic implementation of ->setattr, but
rather a helper to copy attributes from a struct iattr to the inode.
Rename it to setattr_copy to reflect this fact.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs: introduce new truncate sequence

Introduce a new truncate calling sequence into fs/mm subsystems. Rather than
setattr > vmtruncate > truncate, have filesystems call their truncate sequence
from ->setattr if filesystem specific operations are required. vmtruncate is
deprecated, and truncate_pagecache and inode_newsize_ok helpers introduced
previously should be used.

simple_setattr is introduced for simple in-ram filesystems to implement
the new truncate sequence. Eventually all filesystems should be converted
to implement a setattr, and the default code in notify_change should go
away.

simple_setsize is also introduced to perform just the ATTR_SIZE portion
of simple_setattr (ie. changing i_size and trimming pagecache).

To implement the new truncate sequence:
- filesystem specific manipulations (eg freeing blocks) must be done in
the setattr method rather than ->truncate.
- vmtruncate can not be used by core code to trim blocks past i_size in
the event of write failure after allocation, so this must be performed
in the fs code.
- convert usage of helpers block_write_begin, nobh_write_begin,
cont_write_begin, and *blockdev_direct_IO* to use _newtrunc postfixed
variants. These avoid calling vmtruncate to trim blocks (see previous).
- inode_setattr should not be used. generic_setattr is a new function
to be used to copy simple attributes into the generic inode.
- make use of the better opportunity to handle errors with the new sequence.

Big problem with the previous calling sequence: the filesystem is not called
until i_size has already changed. This means it is not allowed to fail the
call, and also it does not know what the previous i_size was. Also, generic
code calling vmtruncate to truncate allocated blocks in case of error had
no good way to return a meaningful error (or, for example, atomically handle
block deallocation).

Cc: Christoph Hellwig <hch@lst.de>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs: use rlimit helpers

Make sure compiler won't do weird things with limits. E.g. fetching them
twice may return 2 different values after writable limits are implemented.

I.e. either use rlimit helpers added in commit 3e10e716abf3 ("resource:
add helpers for fetching rlimits") or ACCESS_ONCE if not applicable.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

dquot: move dquot transfer responsibility into the filesystem

Currently notify_change calls vfs_dq_transfer directly. This means
we tie the quota code into the VFS. Get rid of that and make the
filesystem responsible for the transfer. Most filesystems already
do this, only ufs and udf need the code added, and for jfs it needs to
be enabled unconditionally instead of only when ACLs are enabled.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>

truncate: new helpers

Introduce new truncate helpers truncate_pagecache and inode_newsize_ok.
vmtruncate is also consolidated from mm/memory.c and mm/nommu.c and
into mm/truncate.c.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

vfs: Use lowercase names of quota functions

Use lowercase names of quota functions instead of old uppercase ones.

Signed-off-by: Jan Kara <jack@suse.cz>
CC: Alexander Viro <viro@zeniv.linux.org.uk>

CRED: Wrap task credential accesses in the filesystem subsystem

Wrap access to task credentials so that they can be separated more easily from
the task_struct during the introduction of COW creds.

Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id().

Change some task->e?[ug]id to task_e?[ug]id(). In some places it makes more
sense to use RCU directly rather than a convenient wrapper; these will be
addressed by later patches.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: James Morris <jmorris@namei.org>

[patch] vfs: make security_inode_setattr() calling consistent

Call security_inode_setattr() consistetly before inode_change_ok().
It doesn't make sense to try to "optimize" the i_op->setattr == NULL
case, as most filesystem do define their own setattr function.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

[patch 4/4] vfs: immutable inode checking cleanup

Move the immutable and append-only checks from chmod, chown and utimes
into notify_change(). Checks for immutable and append-only files are
always performed by the VFS and not by the filesystem (see
permission() and may_...() in namei.c), so these belong in
notify_change(), and not in inode_change_ok().

This should be completely equivalent.

CC: Ulrich Drepper <drepper@redhat.com>
CC: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

[patch 1/4] vfs: utimes: move owner check into inode_change_ok()

Add a new ia_valid flag: ATTR_TIMES_SET, to handle the
UTIMES_OMIT/UTIMES_NOW and UTIMES_NOW/UTIMES_OMIT cases. In these
cases neither ATTR_MTIME_SET nor ATTR_ATIME_SET is in the flags, yet
the POSIX draft specifies that permission checking is performed the
same way as if one or both of the times was explicitly set to a
timestamp.

See the path "vfs: utimensat(): fix error checking for
{UTIME_NOW,UTIME_OMIT} case" by Michael Kerrisk for the patch
introducing this behavior.

This is a cleanup, as well as allowing filesystems (NFS/fuse/...) to
perform their own permission checking instead of the default.

CC: Ulrich Drepper <drepper@redhat.com>
CC: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

VFS: make notify_change pass ATTR_KILL_S*ID to setattr operations

When an unprivileged process attempts to modify a file that has the setuid or
setgid bits set, the VFS will attempt to clear these bits. The VFS will set
the ATTR_KILL_SUID or ATTR_KILL_SGID bits in the ia_valid mask, and then call
notify_change to clear these bits and set the mode accordingly.

With a networked filesystem (NFS and CIFS in particular but likely others),
the client machine or process may not have credentials that allow for setting
the mode. In some situations, this can lead to file corruption, an operation
failing outright because the setattr fails, or to races that lead to a mode
change being reverted.

In this situation, we'd like to just leave the handling of this to the server
and ignore these bits. The problem is that by the time the setattr op is
called, the VFS has already reinterpreted the ATTR_KILL_* bits into a mode
change. The setattr operation has no way to know its intent.

The following patch fixes this by making notify_change no longer clear the
ATTR_KILL_SUID and ATTR_KILL_SGID bits in the ia_valid before handing it off
to the setattr inode op. setattr can then check for the presence of these
bits, and if they're set it can assume that the mode change was only for the
purposes of clearing these bits.

This means that we now have an implicit assumption that notify_change is never
called with ATTR_MODE and either ATTR_KILL_S*ID bit set. Nothing currently
enforces that, so this patch also adds a BUG() if that occurs.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Neil Brown <neilb@suse.de>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Jeff Mahoney <jeffm@suse.com>
Cc: "Vladimir V. Saveliev" <vs@namesys.com>
Cc: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Steven French <sfrench@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Implement file posix capabilities

Implement file posix capabilities. This allows programs to be given a
subset of root's powers regardless of who runs them, without having to use
setuid and giving the binary all of root's powers.

This version works with Kaigai Kohei's userspace tools, found at
http://www.kaigai.gr.jp/index.php. For more information on how to use this
patch, Chris Friedhoff has posted a nice page at
http://www.friedhoff.org/fscaps.html.

Changelog:
Nov 27:
Incorporate fixes from Andrew Morton
(security-introduce-file-caps-tweaks and
security-introduce-file-caps-warning-fix)
Fix Kconfig dependency.
Fix change signaling behavior when file caps are not compiled in.

Nov 13:
Integrate comments from Alexey: Remove CONFIG_ ifdef from
capability.h, and use %zd for printing a size_t.

Nov 13:
Fix endianness warnings by sparse as suggested by Alexey
Dobriyan.

Nov 09:
Address warnings of unused variables at cap_bprm_set_security
when file capabilities are disabled, and simultaneously clean
up the code a little, by pulling the new code into a helper
function.

Nov 08:
For pointers to required userspace tools and how to use
them, see http://www.friedhoff.org/fscaps.html.

Nov 07:
Fix the calculation of the highest bit checked in
check_cap_sanity().

Nov 07:
Allow file caps to be enabled without CONFIG_SECURITY, since
capabilities are the default.
Hook cap_task_setscheduler when !CONFIG_SECURITY.
Move capable(TASK_KILL) to end of cap_task_kill to reduce
audit messages.

Nov 05:
Add secondary calls in selinux/hooks.c to task_setioprio and
task_setscheduler so that selinux and capabilities with file
cap support can be stacked.

Sep 05:
As Seth Arnold points out, uid checks are out of place
for capability code.

Sep 01:
Define task_setscheduler, task_setioprio, cap_task_kill, and
task_setnice to make sure a user cannot affect a process in which
they called a program with some fscaps.

One remaining question is the note under task_setscheduler: are we
ok with CAP_SYS_NICE being sufficient to confine a process to a
cpuset?

It is a semantic change, as without fsccaps, attach_task doesn't
allow CAP_SYS_NICE to override the uid equivalence check. But since
it uses security_task_setscheduler, which elsewhere is used where
CAP_SYS_NICE can be used to override the uid equivalence check,
fixing it might be tough.

task_setscheduler
note: this also controls cpuset:attach_task. Are we ok with
CAP_SYS_NICE being used to confine to a cpuset?
task_setioprio
task_setnice
sys_setpriority uses this (through set_one_prio) for another
process. Need same checks as setrlimit

Aug 21:
Updated secureexec implementation to reflect the fact that
euid and uid might be the same and nonzero, but the process
might still have elevated caps.

Aug 15:
Handle endianness of xattrs.
Enforce capability version match between kernel and disk.
Enforce that no bits beyond the known max capability are
set, else return -EPERM.
With this extra processing, it may be worth reconsidering
doing all the work at bprm_set_security rather than
d_instantiate.

Aug 10:
Always call getxattr at bprm_set_security, rather than
caching it at d_instantiate.

[morgan@kernel.org: file-caps clean up for linux/capability.h]
[bunk@kernel.org: unexport cap_inode_killpriv]
Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: James Morris <jmorris@namei.org>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Andrew Morgan <morgan@kernel.org>
Signed-off-by: Andrew Morgan <morgan@kernel.org>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Introduce is_owner_or_cap() to wrap CAP_FOWNER use with fsuid check

Introduce is_owner_or_cap() macro in fs.h, and convert over relevant
users to it. This is done because we want to avoid bugs in the future
where we check for only effective fsuid of the current task against a
file's owning uid, without simultaneously checking for CAP_FOWNER as
well, thus violating its semantics.
[ XFS uses special macros and structures, and in general looked ...
untouchable, so we leave it alone -- but it has been looked over. ]

The (current->fsuid != inode->i_uid) check in generic_permission() and
exec_permission_lite() is left alone, because those operations are
covered by CAP_DAC_OVERRIDE and CAP_DAC_READ_SEARCH. Similarly operations
falling under the purview of CAP_CHOWN and CAP_LEASE are also left alone.

Signed-off-by: Satyam Sharma <ssatyam@cse.iitk.ac.in>
Cc: Al Viro <viro@ftp.linux.org.uk>
Acked-by: Serge E. Hallyn <serge@hallyn.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

header cleaning: don't include smp_lock.h when not used

Remove includes of <linux/smp_lock.h> where it is not used/needed.
Suggested by Al Viro.

Builds cleanly on x86_64, i386, alpha, ia64, powerpc, sparc,
sparc64, and arm (all 59 defconfigs).

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] capable/capability.h (fs/)

fs: Use <linux/capability.h> where capable() is used.

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Acked-by: Tim Schmielau <tim@physik3.uni-rostock.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/attr.c: header included twice

Header included twice.

Signed-off-by: Nicolas Kaiser <nikai@nikai.net>
Signed-off-by: Adrian Bunk <bunk@stusta.de>

[PATCH] Fix some problems with truncate and mtime semantics.

SUS requires that when truncating a file to the size that it currently
is:
truncate and ftruncate should NOT modify ctime or mtime
O_TRUNC SHOULD modify ctime and mtime.

Currently mtime and ctime are always modified on most local
filesystems (side effect of ->truncate) or never modified (on NFS).

With this patch:
ATTR_CTIME|ATTR_MTIME are sent with ATTR_SIZE precisely when
an update of these times is required whether size changes or not
(via a new argument to do_truncate). This allows NFS to do
the right thing for O_TRUNC.
inode_setattr nolonger forces ATTR_MTIME|ATTR_CTIME when the ATTR_SIZE
sets the size to it's current value. This allows local filesystems
to do the right thing for f?truncate.

Also, the logic in inode_setattr is changed a bit so there are two return
points. One returns the error from vmtruncate if it failed, the other
returns 0 (there can be no other failure).

Finally, if vmtruncate succeeds, and ATTR_SIZE is the only change
requested, we now fall-through and mark_inode_dirty. If a filesystem did
not have a ->truncate function, then vmtruncate will have changed i_size,
without marking the inode as 'dirty', and I think this is wrong.

Signed-off-by: Neil Brown <neilb@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] fs/attr.c: remove BUG()

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] inotify

inotify is intended to correct the deficiencies of dnotify, particularly
its inability to scale and its terrible user interface:

* dnotify requires the opening of one fd per each directory
that you intend to watch. This quickly results in too many
open files and pins removable media, preventing unmount.
* dnotify is directory-based. You only learn about changes to
directories. Sure, a change to a file in a directory affects
the directory, but you are then forced to keep a cache of
stat structures.
* dnotify's interface to user-space is awful. Signals?

inotify provides a more usable, simple, powerful solution to file change
notification:

* inotify's interface is a system call that returns a fd, not SIGIO.
You get a single fd, which is select()-able.
* inotify has an event that says "the filesystem that the item
you were watching is on was unmounted."
* inotify can watch directories or files.

Inotify is currently used by Beagle (a desktop search infrastructure),
Gamin (a FAM replacement), and other projects.

See Documentation/filesystems/inotify.txt.

Signed-off-by: Robert Love <rml@novell.com>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!