integrity: eliminate unnecessary "Problem loading X.509 certificate" msg

Currently when the kernel fails to add a cert to the .machine keyring,
it will throw an error immediately in the function integrity_add_key.

Since the kernel will try adding to the .platform keyring next or throw
an error (in the caller of integrity_add_key i.e. add_to_machine_keyring),
so there is no need to throw an error immediately in integrity_add_key.

Reported-by: itrymybest80@protonmail.com
Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2239331
Fixes: d19967764ba8 ("integrity: Introduce a Linux keyring called machine")
Reviewed-by: Eric Snowberg <eric.snowberg@oracle.com>
Signed-off-by: Coiby Xu <coxu@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

integrity: check whether imputed trust is enabled

trust_moklist() is specific to UEFI enabled systems. Other platforms
rely only on the Kconfig.

Define a generic wrapper named imputed_trust_enabled().

Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Tested-by: Nageswara R Sastry <rnsastry@linux.ibm.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

integrity: Enforce digitalSignature usage in the ima and evm keyrings

After being vouched for by a system keyring, only allow keys into the .ima
and .evm keyrings that have the digitalSignature usage field set.

Link: https://lore.kernel.org/all/41dffdaeb7eb7840f7e38bc691fbda836635c9f9.camel@linux.ibm.com
Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
Acked-and-tested-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

integrity: machine keyring CA configuration

Add machine keyring CA restriction options to control the type of
keys that may be added to it. The motivation is separation of
certificate signing from code signing keys. Subsquent work will
limit certificates being loaded into the IMA keyring to code
signing keys used for signature verification.

When no restrictions are selected, all Machine Owner Keys (MOK) are added
to the machine keyring. When CONFIG_INTEGRITY_CA_MACHINE_KEYRING is
selected, the CA bit must be true. Also the key usage must contain
keyCertSign, any other usage field may be set as well.

When CONFIG_INTEGRITY_CA_MACHINE_KEYRING_MAX is selected, the CA bit must
be true. Also the key usage must contain keyCertSign and the
digitialSignature usage may not be set.

Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
Acked-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

integrity: Fix memory leakage in keyring allocation error path

Key restriction is allocated in integrity_init_keyring(). However, if
keyring allocation failed, it is not freed, causing memory leaks.

Fixes: 2b6aa412ff23 ("KEYS: Use structure to capture key restriction function and data")
Signed-off-by: GUO Zihua <guozihua@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

ima: support fs-verity file digest based version 3 signatures

IMA may verify a file's integrity against a "good" value stored in the
'security.ima' xattr or as an appended signature, based on policy. When
the "good value" is stored in the xattr, the xattr may contain a file
hash or signature. In either case, the "good" value is preceded by a
header. The first byte of the xattr header indicates the type of data
- hash, signature - stored in the xattr. To support storing fs-verity
signatures in the 'security.ima' xattr requires further differentiating
the fs-verity signature from the existing IMA signature.

In addition the signatures stored in 'security.ima' xattr, need to be
disambiguated. Instead of directly signing the fs-verity digest, a new
signature format version 3 is defined as the hash of the ima_file_id
structure, which identifies the type of signature and the digest.

The IMA policy defines "which" files are to be measured, verified, and/or
audited. For those files being verified, the policy rules indicate "how"
the file should be verified. For example to require a file be signed,
the appraise policy rule must include the 'appraise_type' option.

appraise_type:= [imasig] | [imasig|modsig] | [sigv3]
where 'imasig' is the original or signature format v2 (default),
where 'modsig' is an appended signature,
where 'sigv3' is the signature format v3.

The policy rule must also indicate the type of digest, if not the IMA
default, by first specifying the digest type:

digest_type:= [verity]

The following policy rule requires fsverity signatures. The rule may be
constrained, for example based on a fsuuid or LSM label.

appraise func=BPRM_CHECK digest_type=verity appraise_type=sigv3

Acked-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

integrity: Only use machine keyring when uefi_check_trust_mok_keys is true

With the introduction of uefi_check_trust_mok_keys, it signifies the end-
user wants to trust the machine keyring as trusted keys. If they have
chosen to trust the machine keyring, load the qualifying keys into it
during boot, then link it to the secondary keyring . If the user has not
chosen to trust the machine keyring, it will be empty and not linked to
the secondary keyring.

Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

KEYS: store reference to machine keyring

Expose the .machine keyring created in integrity code by adding
a reference. Store a reference to the machine keyring in
system keyring code. The system keyring code needs this to complete
the keyring link to the machine keyring.

Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

integrity: Introduce a Linux keyring called machine

Many UEFI Linux distributions boot using shim. The UEFI shim provides
what is called Machine Owner Keys (MOK). Shim uses both the UEFI Secure
Boot DB and MOK keys to validate the next step in the boot chain. The
MOK facility can be used to import user generated keys. These keys can
be used to sign an end-users development kernel build. When Linux
boots, both UEFI Secure Boot DB and MOK keys get loaded in the Linux
.platform keyring.

Define a new Linux keyring called machine. This keyring shall contain just
MOK keys and not the remaining keys in the platform keyring. This new
machine keyring will be used in follow on patches. Unlike keys in the
platform keyring, keys contained in the machine keyring will be trusted
within the kernel if the end-user has chosen to do so.

Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
Tested-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

ima: enable loading of build time generated key on .ima keyring

The kernel currently only loads the kernel module signing key onto the
builtin trusted keyring. Load the module signing key onto the IMA keyring
as well.

Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Acked-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

integrity: Make function integrity_add_key() static

The sparse tool complains as follows:

security/integrity/digsig.c:146:12: warning:
symbol 'integrity_add_key' was not declared. Should it be static?

This function is not used outside of digsig.c, so this
commit marks it static.

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: 60740accf784 ("integrity: Load certs to the platform keyring")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nayna Jain <nayna@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

fs/kernel_file_read: Add "offset" arg for partial reads

To perform partial reads, callers of kernel_read_file*() must have a
non-NULL file_size argument and a preallocated buffer. The new "offset"
argument can then be used to seek to specific locations in the file to
fill the buffer to, at most, "buf_size" per call.

Where possible, the LSM hooks can report whether a full file has been
read or not so that the contents can be reasoned about.

Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20201002173828.2099543-14-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/kernel_read_file: Add file_size output argument

In preparation for adding partial read support, add an optional output
argument to kernel_read_file*() that reports the file size so callers
can reason more easily about their reading progress.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20201002173828.2099543-8-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/kernel_read_file: Switch buffer size arg to size_t

In preparation for further refactoring of kernel_read_file*(), rename
the "max_size" argument to the more accurate "buf_size", and correct
its type to size_t. Add kerndoc to explain the specifics of how the
arguments will be used. Note that with buf_size now size_t, it can no
longer be negative (and was never called with a negative value). Adjust
callers to use it as a "maximum size" when *buf is NULL.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20201002173828.2099543-7-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/kernel_read_file: Remove redundant size argument

In preparation for refactoring kernel_read_file*(), remove the redundant
"size" argument which is not needed: it can be included in the return
code, with callers adjusted. (VFS reads already cannot be larger than
INT_MAX.)

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20201002173828.2099543-6-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/kernel_read_file: Split into separate include file

Move kernel_read_file* out of linux/fs.h to its own linux/kernel_read_file.h
include file. That header gets pulled in just about everywhere
and doesn't really need functions not related to the general fs interface.

Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: James Morris <jamorris@linux.microsoft.com>
Link: https://lore.kernel.org/r/20200706232309.12010-2-scott.branden@broadcom.com
Link: https://lore.kernel.org/r/20201002173828.2099543-4-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/kernel_read_file: Remove FIRMWARE_PREALLOC_BUFFER enum

FIRMWARE_PREALLOC_BUFFER is a "how", not a "what", and confuses the LSMs
that are interested in filtering between types of things. The "how"
should be an internal detail made uninteresting to the LSMs.

Fixes: a098ecd2fa7d ("firmware: support loading into a pre-allocated buffer")
Fixes: fd90bc559bfb ("ima: based on policy verify firmware signatures (pre-allocated buffer)")
Fixes: 4f0496d8ffa3 ("ima: based on policy warn about loading firmware (pre-allocated buffer)")
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201002173828.2099543-2-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

integrity: Remove duplicate pr_fmt definitions

The #define for formatting log messages, pr_fmt, is duplicated in the
files under security/integrity.

This change moves the definition to security/integrity/integrity.h and
removes the duplicate definitions in the other files under
security/integrity.

With this change, the messages in the following files will be prefixed
with 'integrity'.

security/integrity/platform_certs/platform_keyring.c
security/integrity/platform_certs/load_powerpc.c
security/integrity/platform_certs/load_uefi.c
security/integrity/iint.c

e.g. "integrity: Error adding keys to platform keyring %s\n"

And the messages in the following file will be prefixed with 'ima'.

security/integrity/ima/ima_mok.c

e.g. "ima: Allocating IMA blacklist keyring.\n"

For the rest of the files under security/integrity, there will be no
change in the message format.

Suggested-by: Shuah Khan <skhan@linuxfoundation.org>
Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Reviewed-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

ima: Implement support for module-style appended signatures

Implement the appraise_type=imasig|modsig option, allowing IMA to read and
verify modsig signatures.

In case a file has both an xattr signature and an appended modsig, IMA will
only use the appended signature if the key used by the xattr signature
isn't present in the IMA or platform keyring.

Because modsig verification needs to convert from an integrity keyring id
to the keyring itself, add an integrity_keyring_from_id() function in
digsig.c so that integrity_modsig_verify() can use it.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

Revert "Merge tag 'keys-acl-20190703' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs"

This reverts merge 0f75ef6a9cff49ff612f7ce0578bced9d0b38325 (and thus
effectively commits

7a1ade847596 ("keys: Provide KEYCTL_GRANT_PERMISSION")
2e12256b9a76 ("keys: Replace uid/gid/perm permissions checking with an ACL")

that the merge brought in).

It turns out that it breaks booting with an encrypted volume, and Eric
biggers reports that it also breaks the fscrypt tests [1] and loading of
in-kernel X.509 certificates [2].

The root cause of all the breakage is likely the same, but David Howells
is off email so rather than try to work it out it's getting reverted in
order to not impact the rest of the merge window.

[1] https://lore.kernel.org/lkml/20190710011559.GA7973@sol.localdomain/
[2] https://lore.kernel.org/lkml/20190710013225.GB7973@sol.localdomain/

Link: https://lore.kernel.org/lkml/CAHk-=wjxoeMJfeBahnWH=9zShKp2bsVy527vo3_y8HfOdhwAAw@mail.gmail.com/
Reported-by: Eric Biggers <ebiggers@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

keys: Replace uid/gid/perm permissions checking with an ACL

Replace the uid/gid/perm permissions checking on a key with an ACL to allow
the SETATTR and SEARCH permissions to be split. This will also allow a
greater range of subjects to represented.

============
WHY DO THIS?
============

The problem is that SETATTR and SEARCH cover a slew of actions, not all of
which should be grouped together.

For SETATTR, this includes actions that are about controlling access to a
key:

(1) Changing a key's ownership.

(2) Changing a key's security information.

(3) Setting a keyring's restriction.

And actions that are about managing a key's lifetime:

(4) Setting an expiry time.

(5) Revoking a key.

and (proposed) managing a key as part of a cache:

(6) Invalidating a key.

Managing a key's lifetime doesn't really have anything to do with
controlling access to that key.

Expiry time is awkward since it's more about the lifetime of the content
and so, in some ways goes better with WRITE permission. It can, however,
be set unconditionally by a process with an appropriate authorisation token
for instantiating a key, and can also be set by the key type driver when a
key is instantiated, so lumping it with the access-controlling actions is
probably okay.

As for SEARCH permission, that currently covers:

(1) Finding keys in a keyring tree during a search.

(2) Permitting keyrings to be joined.

(3) Invalidation.

But these don't really belong together either, since these actions really
need to be controlled separately.

Finally, there are number of special cases to do with granting the
administrator special rights to invalidate or clear keys that I would like
to handle with the ACL rather than key flags and special checks.


===============
WHAT IS CHANGED
===============

The SETATTR permission is split to create two new permissions:

(1) SET_SECURITY - which allows the key's owner, group and ACL to be
changed and a restriction to be placed on a keyring.

(2) REVOKE - which allows a key to be revoked.

The SEARCH permission is split to create:

(1) SEARCH - which allows a keyring to be search and a key to be found.

(2) JOIN - which allows a keyring to be joined as a session keyring.

(3) INVAL - which allows a key to be invalidated.

The WRITE permission is also split to create:

(1) WRITE - which allows a key's content to be altered and links to be
added, removed and replaced in a keyring.

(2) CLEAR - which allows a keyring to be cleared completely. This is
split out to make it possible to give just this to an administrator.

(3) REVOKE - see above.


Keys acquire ACLs which consist of a series of ACEs, and all that apply are
unioned together. An ACE specifies a subject, such as:

(*) Possessor - permitted to anyone who 'possesses' a key
(*) Owner - permitted to the key owner
(*) Group - permitted to the key group
(*) Everyone - permitted to everyone

Note that 'Other' has been replaced with 'Everyone' on the assumption that
you wouldn't grant a permit to 'Other' that you wouldn't also grant to
everyone else.

Further subjects may be made available by later patches.

The ACE also specifies a permissions mask. The set of permissions is now:

VIEW Can view the key metadata
READ Can read the key content
WRITE Can update/modify the key content
SEARCH Can find the key by searching/requesting
LINK Can make a link to the key
SET_SECURITY Can change owner, ACL, expiry
INVAL Can invalidate
REVOKE Can revoke
JOIN Can join this keyring
CLEAR Can clear this keyring


The KEYCTL_SETPERM function is then deprecated.

The KEYCTL_SET_TIMEOUT function then is permitted if SET_SECURITY is set,
or if the caller has a valid instantiation auth token.

The KEYCTL_INVALIDATE function then requires INVAL.

The KEYCTL_REVOKE function then requires REVOKE.

The KEYCTL_JOIN_SESSION_KEYRING function then requires JOIN to join an
existing keyring.

The JOIN permission is enabled by default for session keyrings and manually
created keyrings only.


======================
BACKWARD COMPATIBILITY
======================

To maintain backward compatibility, KEYCTL_SETPERM will translate the
permissions mask it is given into a new ACL for a key - unless
KEYCTL_SET_ACL has been called on that key, in which case an error will be
returned.

It will convert possessor, owner, group and other permissions into separate
ACEs, if each portion of the mask is non-zero.

SETATTR permission turns on all of INVAL, REVOKE and SET_SECURITY. WRITE
permission turns on WRITE, REVOKE and, if a keyring, CLEAR. JOIN is turned
on if a keyring is being altered.

The KEYCTL_DESCRIBE function translates the ACL back into a permissions
mask to return depending on possessor, owner, group and everyone ACEs.

It will make the following mappings:

(1) INVAL, JOIN -> SEARCH

(2) SET_SECURITY -> SETATTR

(3) REVOKE -> WRITE if SETATTR isn't already set

(4) CLEAR -> WRITE

Note that the value subsequently returned by KEYCTL_DESCRIBE may not match
the value set with KEYCTL_SETATTR.


=======
TESTING
=======

This passes the keyutils testsuite for all but a couple of tests:

(1) tests/keyctl/dh_compute/badargs: The first wrong-key-type test now
returns EOPNOTSUPP rather than ENOKEY as READ permission isn't removed
if the type doesn't have ->read(). You still can't actually read the
key.

(2) tests/keyctl/permitting/valid: The view-other-permissions test doesn't
work as Other has been replaced with Everyone in the ACL.

Signed-off-by: David Howells <dhowells@redhat.com>

integrity: Fix __integrity_init_keyring() section mismatch

With gcc-4.6.3:

WARNING: vmlinux.o(.text.unlikely+0x24c64): Section mismatch in reference from the function __integrity_init_keyring() to the function .init.text:set_platform_trusted_keys()
The function __integrity_init_keyring() references
the function __init set_platform_trusted_keys().
This is often because __integrity_init_keyring lacks a __init
annotation or the annotation of set_platform_trusted_keys is wrong.

Indeed, if the compiler decides not to inline __integrity_init_keyring(),
a warning is issued.

Fix this by adding the missing __init annotation.

Fixes: 9dc92c45177ab70e ("integrity: Define a trusted platform keyring")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Nayna Jain <nayna@linux.ibm.com>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation version 2 of the license

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 315 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190115.503150771@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

integrity, KEYS: add a reference to platform keyring

commit 9dc92c45177a ("integrity: Define a trusted platform keyring")
introduced a .platform keyring for storing preboot keys, used for
verifying kernel image signatures. Currently only IMA-appraisal is able
to use the keyring to verify kernel images that have their signature
stored in xattr.

This patch exposes the .platform keyring, making it accessible for
verifying PE signed kernel images as well.

Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Kairui Song <kasong@redhat.com>
Cc: David Howells <dhowells@redhat.com>
[zohar@linux.ibm.com: fixed checkpatch errors, squashed with patch fix]
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

integrity: Remove references to module keyring

From what I can tell, it has never been used.

Mimi: This was introduced prior to Rusty's decision to use appended
signatures for kernel modules.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Acked-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: James Morris <james.morris@microsoft.com>

integrity: Load certs to the platform keyring

The patch refactors integrity_load_x509(), making it a wrapper for a new
function named integrity_add_key(). This patch also defines a new
function named integrity_load_cert() for loading the platform keys.

Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: James Morris <james.morris@microsoft.com>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

integrity: Define a trusted platform keyring

On secure boot enabled systems, a verified kernel may need to kexec
additional kernels. For example, it may be used as a bootloader needing
to kexec a target kernel or it may need to kexec a crashdump kernel. In
such cases, it may want to verify the signature of the next kernel
image.

It is further possible that the kernel image is signed with third party
keys which are stored as platform or firmware keys in the 'db' variable.
The kernel, however, can not directly verify these platform keys, and an
administrator may therefore not want to trust them for arbitrary usage.
In order to differentiate platform keys from other keys and provide the
necessary separation of trust, the kernel needs an additional keyring to
store platform keys.

This patch creates the new keyring called ".platform" to isolate keys
provided by platform from keys by kernel. These keys are used to
facilitate signature verification during kexec. Since the scope of this
keyring is only the platform/firmware keys, it cannot be updated from
userspace.

This keyring can be enabled by setting CONFIG_INTEGRITY_PLATFORM_KEYRING.

Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: James Morris <james.morris@microsoft.com>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

security/integrity: remove unnecessary 'init_keyring' variable

The 'init_keyring' variable actually just gave the value of
CONFIG_INTEGRITY_TRUSTED_KEYRING. We should check the config option
directly instead. No change in behavior; this just simplifies the code.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

security/integrity: constify some read-only data

Constify some static data that is never modified,
so that it is placed in .rodata.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

integrity/security: fix digsig.c build error with header file

security/integrity/digsig.c has build errors on some $ARCH due to a
missing header file, so add it.

security/integrity/digsig.c:146:2: error: implicit declaration of function 'vfree' [-Werror=implicit-function-declaration]

Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: linux-integrity@vger.kernel.org
Link: http://kisskb.ellerman.id.au/kisskb/head/13396/
Signed-off-by: James Morris <james.morris@microsoft.com>

integrity: use kernel_read_file_from_path() to read x509 certs

The CONFIG_IMA_LOAD_X509 and CONFIG_EVM_LOAD_X509 options permit
loading x509 signed certificates onto the trusted keyrings without
verifying the x509 certificate file's signature.

This patch replaces the call to the integrity_read_file() specific
function with the common kernel_read_file_from_path() function.
To avoid verifying the file signature, this patch defines
READING_X509_CERTFICATE.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

KEYS: Use structure to capture key restriction function and data

Replace struct key's restrict_link function pointer with a pointer to
the new struct key_restriction. The structure contains pointers to the
restriction function as well as relevant data for evaluating the
restriction.

The garbage collector checks restrict_link->keytype when key types are
unregistered. Restrictions involving a removed key type are converted
to use restrict_link_reject so that restrictions cannot be removed by
unregistering key types.

Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>

security/integrity: Harden against malformed xattrs

In general the handling of IMA/EVM xattrs is good, but I found
a few locations where either the xattr size or the value of the
type field in the xattr are not checked. Add a few simple checks
to these locations to prevent malformed or malicious xattrs from
causing problems.

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

IMA: Use the the system trusted keyrings instead of .ima_mok

Add a config option (IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY)
that, when enabled, allows keys to be added to the IMA keyrings by
userspace - with the restriction that each must be signed by a key in the
system trusted keyrings.

EPERM will be returned if this option is disabled, ENOKEY will be returned if
no authoritative key can be found and EKEYREJECTED will be returned if the
signature doesn't match. Other errors such as ENOPKG may also be returned.

If this new option is enabled, the builtin system keyring is searched, as is
the secondary system keyring if that is also enabled. Intermediate keys
between the builtin system keyring and the key being added can be added to
the secondary keyring (which replaces .ima_mok) to form a trust chain -
provided they are also validly signed by a key in one of the trusted keyrings.

The .ima_mok keyring is then removed and the IMA blacklist keyring gets its
own config option (IMA_BLACKLIST_KEYRING).

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

KEYS: Remove KEY_FLAG_TRUSTED and KEY_ALLOC_TRUSTED

Remove KEY_FLAG_TRUSTED and KEY_ALLOC_TRUSTED as they're no longer
meaningful. Also we can drop the trusted flag from the preparse structure.

Given this, we no longer need to pass the key flags through to
restrict_link().

Further, we can now get rid of keyring_restrict_trusted_only() also.

Signed-off-by: David Howells <dhowells@redhat.com>

KEYS: Move the point of trust determination to __key_link()

Move the point at which a key is determined to be trustworthy to
__key_link() so that we use the contents of the keyring being linked in to
to determine whether the key being linked in is trusted or not.

What is 'trusted' then becomes a matter of what's in the keyring.

Currently, the test is done when the key is parsed, but given that at that
point we can only sensibly refer to the contents of the system trusted
keyring, we can only use that as the basis for working out the
trustworthiness of a new key.

With this change, a trusted keyring is a set of keys that once the
trusted-only flag is set cannot be added to except by verification through
one of the contained keys.

Further, adding a key into a trusted keyring, whilst it might grant
trustworthiness in the context of that keyring, does not automatically
grant trustworthiness in the context of a second keyring to which it could
be secondarily linked.

To accomplish this, the authentication data associated with the key source
must now be retained. For an X.509 cert, this means the contents of the
AuthorityKeyIdentifier and the signature data.


If system keyrings are disabled then restrict_link_by_builtin_trusted()
resolves to restrict_link_reject(). The integrity digital signature code
still works correctly with this as it was previously using
KEY_FLAG_TRUSTED_ONLY, which doesn't permit anything to be added if there
is no system keyring against which trust can be determined.

Signed-off-by: David Howells <dhowells@redhat.com>

KEYS: Add a facility to restrict new links into a keyring

Add a facility whereby proposed new links to be added to a keyring can be
vetted, permitting them to be rejected if necessary. This can be used to
block public keys from which the signature cannot be verified or for which
the signature verification fails. It could also be used to provide
blacklisting.

This affects operations like add_key(), KEYCTL_LINK and KEYCTL_INSTANTIATE.

To this end:

(1) A function pointer is added to the key struct that, if set, points to
the vetting function. This is called as:

int (*restrict_link)(struct key *keyring,
const struct key_type *key_type,
unsigned long key_flags,
const union key_payload *key_payload),

where 'keyring' will be the keyring being added to, key_type and
key_payload will describe the key being added and key_flags[*] can be
AND'ed with KEY_FLAG_TRUSTED.

[*] This parameter will be removed in a later patch when
KEY_FLAG_TRUSTED is removed.

The function should return 0 to allow the link to take place or an
error (typically -ENOKEY, -ENOPKG or -EKEYREJECTED) to reject the
link.

The pointer should not be set directly, but rather should be set
through keyring_alloc().

Note that if called during add_key(), preparse is called before this
method, but a key isn't actually allocated until after this function
is called.

(2) KEY_ALLOC_BYPASS_RESTRICTION is added. This can be passed to
key_create_or_update() or key_instantiate_and_link() to bypass the
restriction check.

(3) KEY_FLAG_TRUSTED_ONLY is removed. The entire contents of a keyring
with this restriction emplaced can be considered 'trustworthy' by
virtue of being in the keyring when that keyring is consulted.

(4) key_alloc() and keyring_alloc() take an extra argument that will be
used to set restrict_link in the new key. This ensures that the
pointer is set before the key is published, thus preventing a window
of unrestrictedness. Normally this argument will be NULL.

(5) As a temporary affair, keyring_restrict_trusted_only() is added. It
should be passed to keyring_alloc() as the extra argument instead of
setting KEY_FLAG_TRUSTED_ONLY on a keyring. This will be replaced in
a later patch with functions that look in the appropriate places for
authoritative keys.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

integrity: define '.evm' as a builtin 'trusted' keyring

Require all keys added to the EVM keyring be signed by an
existing trusted key on the system trusted keyring.

This patch also switches IMA to use integrity_init_keyring().

Changes in v3:
* Added 'init_keyring' config based variable to skip initializing
keyring instead of using __integrity_init_keyring() wrapper.
* Added dependency back to CONFIG_IMA_TRUSTED_KEYRING

Changes in v2:
* Replace CONFIG_EVM_TRUSTED_KEYRING with IMA and EVM common
CONFIG_INTEGRITY_TRUSTED_KEYRING configuration option
* Deprecate CONFIG_IMA_TRUSTED_KEYRING but keep it for config
file compatibility. (Mimi Zohar)

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

integrity: prevent loading untrusted certificates on the IMA trusted keyring

If IMA_LOAD_X509 is enabled, either directly or indirectly via
IMA_APPRAISE_SIGNED_INIT, certificates are loaded onto the IMA
trusted keyring by the kernel via key_create_or_update(). When
the KEY_ALLOC_TRUSTED flag is provided, certificates are loaded
without first verifying the certificate is properly signed by a
trusted key on the system keyring. This patch removes the
KEY_ALLOC_TRUSTED flag.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
Cc: <stable@vger.kernel.org> # 3.19+
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

integrity: add validity checks for 'path' parameter

This patch adds validity checks for 'path' parameter and
makes it const.

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

integrity: provide a function to load x509 certificate from the kernel

Provide the function to load x509 certificates from the kernel into the
integrity kernel keyring.

Changes in v2:
* configuration option removed
* function declared as '__init'

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

integrity: add missing '__init' keyword for integrity_init_keyring()

integrity_init_keyring() is used only from kernel '__init'
functions. Add it there as well.

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

ima: define '.ima' as a builtin 'trusted' keyring

Require all keys added to the IMA keyring be signed by an
existing trusted key on the system trusted keyring.

Changelog v6:
- remove ifdef CONFIG_IMA_TRUSTED_KEYRING in C code - Dmitry
- update Kconfig dependency and help
- select KEYS_DEBUG_PROC_KEYS - Dmitry

Changelog v5:
- Move integrity_init_keyring() to init_ima() - Dmitry
- reset keyring[id] on failure - Dmitry

Changelog v1:
- don't link IMA trusted keyring to user keyring

Changelog:
- define stub integrity_init_keyring() function (reported-by Fengguang Wu)
- differentiate between regular and trusted keyring names.
- replace printk with pr_info (D. Kasatkin)
- only make the IMA keyring a trusted keyring (reported-by D. Kastatkin)
- define stub integrity_init_keyring() definition based on
CONFIG_INTEGRITY_SIGNATURE, not CONFIG_INTEGRITY_ASYMMETRIC_KEYS.
(reported-by Jim Davis)

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Acked-by: David Howells <dhowells@redhat.com>

Revert "ima: define '_ima' as a builtin 'trusted' keyring"

This reverts commit 217091dd7a7a1bdac027ddb7c5a25f6ac0b8e241, which
caused the following build error:

security/integrity/digsig.c:70:5: error: redefinition of ‘integrity_init_keyring’
security/integrity/integrity.h:149:12: note: previous definition of ‘integrity_init_keyring’ w
security/integrity/integrity.h:149:12: warning: ‘integrity_init_keyring’ defined but not used

reported by Krzysztof Kolasa. Mimi says:

"I made the classic mistake of requesting this patch to be upstreamed
at the last second, rather than waiting until the next open window.

At this point, the best course would probably be to revert the two
commits and fix them for the next open window"

Reported-by: Krzysztof Kolasa <kkolasa@winsoft.pl>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

ima: define '_ima' as a builtin 'trusted' keyring

Require all keys added to the IMA keyring be signed by an
existing trusted key on the system trusted keyring.

Changelog:
- define stub integrity_init_keyring() function (reported-by Fengguang Wu)
- differentiate between regular and trusted keyring names.
- replace printk with pr_info (D. Kasatkin)

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>

ima: pass full xattr with the signature

For possibility to use xattr type for new signature formats,
pass full xattr to the signature verification function.

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

ima: fix script messages

Fix checkpatch, lindent, etc, warnings/errors

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

ima: digital signature verification using asymmetric keys

Asymmetric keys were introduced in linux-3.7 to verify the signature on
signed kernel modules. The asymmetric keys infrastructure abstracts the
signature verification from the crypto details. This patch adds IMA/EVM
signature verification using asymmetric keys. Support for additional
signature verification methods can now be delegated to the asymmetric
key infrastructure.

Although the module signature header and the IMA/EVM signature header
could use the same format, to minimize the signature length and save
space in the extended attribute, this patch defines a new IMA/EVM
header format. The main difference is that the key identifier is a
sha1[12 - 19] hash of the key modulus and exponent, similar to the
current implementation. The only purpose of the key identifier is to
identify the corresponding key in the kernel keyring. ima-evm-utils
was updated to support the new signature format.

While asymmetric signature verification functionality supports many
different hash algorithms, the hash used in this patch is calculated
during the IMA collection phase, based on the configured algorithm.
The default algorithm is sha1, but for backwards compatibility md5
is supported. Due to this current limitation, signatures should be
generated using a sha1 hash algorithm.

Changes in this patch:
- Functionality has been moved to separate source file in order to get rid of
in source #ifdefs.
- keyid is derived according to the RFC 3280. It does not require to assign
IMA/EVM specific "description" when loading X509 certificate. Kernel
asymmetric key subsystem automatically generate the description. Also
loading a certificate does not require using of ima-evm-utils and can be
done using keyctl only.
- keyid size is reduced to 32 bits to save xattr space. Key search is done
using partial match functionality of asymmetric_key_match().
- Kconfig option title was changed

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

integrity: digital signature verification using multiple keyrings

Define separate keyrings for each of the different use cases - evm, ima,
and modules. Using different keyrings improves search performance, and also
allows "locking" specific keyring to prevent adding new keys.
This is useful for evm and module keyrings, when keys are usually only
added from initramfs.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>