veriexec: Simplify the initialization of loader tunable

The loader tunable 'security.mac.veriexec.block_unlink' has been
already flagged with CTLFLAG_RDTUN, no need to re-fetch it with
TUNABLE_INT_FETCH.

While here move the definition of sysctl knob out of function body,
which is more common in FreeBSD.

No functional change intended.

Reviewed by: stevek
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D42132

veriexec: Add option MAC_VERIEXEC_DEBUG

Obtained from: Juniper Networks, Inc.

veriexec: mac_veriexec_syscall compat32 support

Some 32bit apps may need to be able to use
MAC_VERIEXEC_GET_PARAMS_PID_SYSCALL
MAC_VERIEXEC_GET_PARAMS_PATH_SYSCALL

Therefore compat32 support is required.

Obtained from: Juniper Networks, Inc.

veriexec: Additional functionality for MAC/veriexec

Ensure veriexec opens the file before doing any read operations.

When the MAC_VERIEXEC_CHECK_PATH_SYSCALL syscall is requested, veriexec
needs to open the file before calling mac_veriexec_check_vp. This is to
ensure any set up is done by the file system. Most file systems do not
explicitly need an open, but some (e.g. virtfs) require initialization
of access tokens (file identifiers, etc.) before doing any read or write
operations.

The evaluate_fingerprint() function needs to ensure it has an open file
for reading in order to evaluate the fingerprint. The ideal solution is
to have a hook after the VOP_OPEN call in vn_open. For now, we open the
file for reading, envaluate the fingerprint, and close the file. While
this leaves a potential hole that could possibly be taken advantage of
by a dedicated aversary, this code path is not typically visited often
in our use cases, as we primarily encounter verified mounts and not
individual files. This should be considered a temporary workaround until
discussions about the post-open hook have concluded and the hook becomes
available.

Add MAC_VERIEXEC_GET_PARAMS_PATH_SYSCALL and
MAC_VERIEXEC_GET_PARAMS_PID_SYSCALL to mac_veriexec_syscall so we can
fetch and check label contents in an unconstrained manner.

Add a check for PRIV_VERIEXEC_CONTROL to do ioctl on /dev/veriexec

Make it clear that trusted process cannot be debugged. Attempts to debug
a trusted process already fail, but the failure path is very obscure.
Add an explicit check for VERIEXEC_TRUSTED in
mac_veriexec_proc_check_debug.

We need mac_veriexec_priv_check to not block PRIV_KMEM_WRITE if
mac_priv_gant() says it is ok.

Reviewed by: sjg
Obtained from: Juniper Networks, Inc.

veriexec: Add SPDX-License-Identifier

mac_veriexec: add mac_priv_grant check for NODEV

Allow other MAC modules to override some veriexec checks.

We need two new privileges:
PRIV_VERIEXEC_DIRECT process wants to override 'indirect' flag
on interpreter
PRIV_VERIEXEC_NOVERIFY typically associated with PRIV_VERIEXEC_DIRECT
allow override of O_VERIFY

We also need to check for PRIV_VERIEXEC_NOVERIFY override
for FINGERPRINT_NODEV and FINGERPRINT_NOENTRY.
This will only happen if parent had PRIV_VERIEXEC_DIRECT override.

This allows for MAC modules to selectively allow some applications to
run without verification.

Needless to say, this is extremely dangerous and should only be used
sparingly and carefully.

Obtained from: Juniper Networks, Inc.

Reviewers: sjg
Subscribers: imp, dab

Differential Revision: https://reviews.freebsd.org/D39537

veriexec: Improve comments

Make it clear we're checking to see if the target is a verified file and
prevent its replacement if so.

Sponsored by: Netflix
Reviewed by: rpokala
Differential Revision: https://reviews.freebsd.org/D39079

Increase protection provided by veriexec with new unlink/rename hooks.

Functions implemented :

- mac_veriexec_vnode_check_unlink: Unlink on a file has been
requested and requires validation. This function prohibits the
deleting a protected file (or deleting one of these hard links, if
any).
- mac_veriexec_vnode_check_rename_from: Rename the file has been
requested and must be validated. This function controls the renaming
of protected file
- mac_veriexec_vnode_check_rename_to: File overwrite rename has been
requested and must be validated. This function prevent overwriting of
a file protected (overwriting by mv command).

The 3 fonctions together aim to control the 'removal' (via unlink) and
the 'mv' on files protected by veriexec. The intention is to reach the
functional level of NetBSD veriexec.

Add sysctl node security.mac.veriexec.unlink to toggle control on
syscall unlink.

Add tunable kernel variable security.mac.veriexec.block_unlink to toggle
unlink protection. Add the corresponding read-only sysctl.

[ tidied up commit message, trailing whitespace, long lines, { placement ]

Reviewed by: sjg, imp
Pull Request: https://github.com/freebsd/freebsd-src/pull/613

mac_veriexec: Authorize reads of secured sysctls

Writes to sysctls flagged with CTLFLAG_SECURE are blocked if the appropriate secure level is set. mac_veriexec does not behave this way, it blocks such sysctls in read-only mode as well.

This change aims to make mac_veriexec behave like secure levels, as it was meant by the original commit ed377cf41.

Reviewed by: sjg
Differential revision: https://reviews.freebsd.org/D34327
Obtained from: Stormshield

vfs: NDFREE(&nd, NDF_ONLY_PNBUF) -> NDFREE_PNBUF(&nd)

vfs: remove the unused thread argument from NDINIT*

See b4a58fbf640409a1 ("vfs: remove cn_thread")

Bump __FreeBSD_version to 1400043.

Fix mac_veriexec version mismatch

mac_veriexec sets its version to 1, but the mac_veriexec_shaX modules which depend on it expect MAC_VERIEXEC_VERSION = 2.
Be consistent and use MAC_VERIEXEC_VERSION everywhere.
This unbreaks loading of mac_veriexec modules at boot time.

Authored by: Kornel Duleba <mindal@semihalf.com>
Obtained from: Semihalf
Sponsored by: Stormshield
Differential Revision: https://reviews.freebsd.org/D31268

Convert remaining cap_rights_init users to cap_rights_init_one

semantic patch:

@@

expression rights, r;

@@

- cap_rights_init(&rights, r)
+ cap_rights_init_one(&rights, r)

Mark more nodes as CTLFLAG_MPSAFE or CTLFLAG_NEEDGIANT (17 of many)

r357614 added CTLFLAG_NEEDGIANT to make it easier to find nodes that are
still not MPSAFE (or already are but aren’t properly marked).
Use it in preparation for a general review of all nodes.

This is non-functional change that adds annotations to SYSCTL_NODE and
SYSCTL_PROC nodes using one of the soon-to-be-required flags.

Mark all obvious cases as MPSAFE. All entries that haven't been marked
as MPSAFE before are by default marked as NEEDGIANT

Approved by: kib (mentor, blanket)
Commented by: kib, gallatin, melifaro
Differential Revision: https://reviews.freebsd.org/D23718

vfs: eliminate v_tag from struct vnode

There was only one consumer and it was using it incorrectly.

It is given an equivalent hack.

Reviewed by: jeff
Differential Revision: https://reviews.freebsd.org/D23037

vfs: drop the mostly unused flags argument from VOP_UNLOCK

Filesystems which want to use it in limited capacity can employ the
VOP_UNLOCK_FLAGS macro.

Reviewed by: kib (previous version)
Differential Revision: https://reviews.freebsd.org/D21427

Obtain a shared lock instead of exclusive in the MAC/veriexec
MAC_VERIEXEC_CHECK_PATH_SYSCALL per-MAC policy system call.

When we are checking the status of the fingerprint on a vnode using the
per-MAC-policy syscall, we do not need an exclusive lock on the vnode.

Even if there is more than one thread requesting the status at the same time,
the worst we can end up doing is processing the file more than once.

This can potentially be improved in the future with offloading the fingerprint
evaluation to a separate thread and blocking until the update completes. But
for now the race is acceptable.

Obtained from: Juniper Networks, Inc.
MFC after: 1 week

sysctls which should be restricted when securelevel is raised should also
be restricted when veriexec is enforced.

Add mpo_system_check_sysctl method to mac_veriexec which does this.

Obtained from: Juniper Networks, Inc.
MFC after: 1 week

Fix format strings for some debug messages that could have arguments that
are different types across architectures by using %ju and typecasting to
uintmax_t, where appropriate.

Obtained from: Juniper Networks, Inc.
MFC after: 1 week

Ensure we have obtained a lock on the process before calling
mac_veriexec_get_executable_flags(). Only try locking/unlocking if the caller
has not already acquired the process lock.

Obtained from: Juniper Networks, Inc.
MFC after: 1 week

Add mpo_vnode_check_setmode MAC method to MAC/veriexec.
In the method, disallow changing SUID/SGID on verified files.

Obtained from: Juniper Networks, Inc.

Fix a typo which could cause a build breakage when building with MAC/veriexec
enabled in the kernel config.

Remove unused mac_veriexec_print_db prototype in internal header file.

MAC/veriexec implements a verified execution environment using the MAC
framework.

The code is organized into a few distinct pieces:

* The meta-data store (in veriexec_metadata.c) which maps a file system
identifier, file identifier, and generation key tuple to veriexec
meta-data record.

* Fingerprint management (in veriexec_fingerprint.c) which deals with
calculating the cryptographic hash for a file and verifying it. It also
manages the loadable fingerprint modules.

* MAC policy implementation (in mac_veriexec.c) which implements the
following MAC methods:

mpo_init
Initializes the veriexec state, meta-data store, fingerprint modules,
and registers mount and unmount EVENTHANDLERs

mpo_syscall
Implements the following per-policy system calls:
MAC_VERIEXEC_CHECK_FD_SYSCALL
Check a file descriptor to see if the referenced file has a valid
fingerprint.
MAC_VERIEXEC_CHECK_PATH_SYSCALL
Check a path to see if the referenced file has a valid fingerprint.

mpo_kld_check_load
Check if loading a kld is allowed. This checks if the referenced vnode
has a valid fingerprint.

mpo_mount_destroy_label
Clears the veriexec slot data in a mount point label.

mpo_mount_init_label
Initializes the veriexec slot data in a mount point label.
The file system identifier is saved in the veriexec slot data.

mpo_priv_check
Check if a process is allowed to write to /dev/kmem and /dev/mem
devices.
If a process is flagged as trusted, it is allowed to write.

mpo_proc_check_debug
Check if a process is allowed to be debugged. If a process is not
flagged with VERIEXEC_NOTRACE, then debugging is allowed.

mpo_vnode_check_exec
Check is an exectuable is allowed to run. If veriexec is not enforcing
or the executable has a valid fingerprint, then it is allowed to run.
NOTE: veriexec will complain about mismatched fingerprints if it is
active, regardless of the state of the enforcement.

mpo_vnode_check_open
Check is a file is allowed to be opened. If verification was not
requested, veriexec is not enforcing, or the file has a valid
fingerprint, then veriexec will allow the file to be opened.

mpo_vnode_copy_label
Copies the veriexec slot data from one label to another.

mpo_vnode_destroy_label
Clears the veriexec slot data in a vnode label.

mpo_vnode_init_label
Initializes the veriexec slot data in a vnode label.
The fingerprint status for the file is stored in the veriexec slot data.

* Some sysctls, under security.mac.veriexec, for setting debug level,
fetching the current state in a human-readable form, and dumping the
fingerprint database are implemented.

* The MAC policy implementation source file also contains some utility
functions.

* A set of fingerprint modules for the following cryptographic hash
algorithms:
RIPEMD-160, SHA1, SHA2-256, SHA2-384, SHA2-512

* Loadable module builds for MAC/veriexec and fingerprint modules.

WARNING: Using veriexec with NFS (or other network-based) file systems is
not recommended as one cannot guarantee the integrity of the files
served, nor the uniqueness of file system identifiers which are
used as key in the meta-data store.

Reviewed by: ian, jtl
Obtained from: Juniper Networks, Inc.
Differential Revision: https://reviews.freebsd.org/D8554