A panic happens in ima_match_policy:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
PGD 42f873067 P4D 0
Oops: 0000 [#1] SMP NOPTI
CPU: 5 PID: 1286325 Comm: kubeletmonit.sh
Kdump: loaded Tainted: P
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
               BIOS 0.0.0 02/06/2015
RIP: 0010:ima_match_policy+0x84/0x450
Code: 49 89 fc 41 89 cf 31 ed 89 44 24 14 eb 1c 44 39
      7b 18 74 26 41 83 ff 05 74 20 48 8b 1b 48 3b 1d
      f2 b9 f4 00 0f 84 9c 01 00 00 <44> 85 73 10 74 ea
      44 8b 6b 14 41 f6 c5 01 75 d4 41 f6 c5 02 74 0f
RSP: 0018:ff71570009e07a80 EFLAGS: 00010207
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000200
RDX: ffffffffad8dc7c0 RSI: 0000000024924925 RDI: ff3e27850dea2000
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffffabfce739
R10: ff3e27810cc42400 R11: 0000000000000000 R12: ff3e2781825ef970
R13: 00000000ff3e2785 R14: 000000000000000c R15: 0000000000000001
FS:  00007f5195b51740(0000)
GS:ff3e278b12d40000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000010 CR3: 0000000626d24002 CR4: 0000000000361ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 ima_get_action+0x22/0x30
 process_measurement+0xb0/0x830
 ? page_add_file_rmap+0x15/0x170
 ? alloc_set_pte+0x269/0x4c0
 ? prep_new_page+0x81/0x140
 ? simple_xattr_get+0x75/0xa0
 ? selinux_file_open+0x9d/0xf0
 ima_file_check+0x64/0x90
 path_openat+0x571/0x1720
 do_filp_open+0x9b/0x110
 ? page_counter_try_charge+0x57/0xc0
 ? files_cgroup_alloc_fd+0x38/0x60
 ? __alloc_fd+0xd4/0x250
 ? do_sys_open+0x1bd/0x250
 do_sys_open+0x1bd/0x250
 do_syscall_64+0x5d/0x1d0
 entry_SYSCALL_64_after_hwframe+0x65/0xca

Commit c7423dbd ("ima: Handle -ESTALE returned by
ima_filter_rule_match()") introduced call to ima_lsm_copy_rule within a
RCU read-side critical section which contains kmalloc with GFP_KERNEL.
This implies a possible sleep and violates limitations of RCU read-side
critical sections on non-PREEMPT systems.

Sleeping within RCU read-side critical section might cause
synchronize_rcu() returning early and break RCU protection, allowing a
UAF to happen.

The root cause of this issue could be described as follows:
|	Thread A	|	Thread B	|
|			|ima_match_policy	|
|			|  rcu_read_lock	|
|ima_lsm_update_rule	|			|
|  synchronize_rcu	|			|
|			|    kmalloc(GFP_KERNEL)|
|			|      sleep		|
==> synchronize_rcu returns early
|  kfree(entry)		|			|
|			|    entry = entry->next|
==> UAF happens and entry now becomes NULL (or could be anything).
|			|    entry->action	|
==> Accessing entry might cause panic.

To fix this issue, we are converting all kmalloc that is called within
RCU read-side critical section to use GFP_ATOMIC.

Fixes: c7423dbd ("ima: Handle -ESTALE returned by ima_filter_rule_match()")
Cc: stable@vger.kernel.org
Signed-off-by: GUO Zihua <guozihua@huawei.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: fixed missing comment, long lines, !CONFIG_IMA_LSM_RULES case]
Signed-off-by: Paul Moore <paul@paul-moore.com>

The current security_inode_setxattr() and security_inode_removexattr()
hooks rely on individual LSMs to either call into the associated
capability hooks (cap_inode_setxattr() or cap_inode_removexattr()), or
return a magic value of 1 to indicate that the LSM layer itself should
perform the capability checks.  Unfortunately, with the default return
value for these LSM hooks being 0, an individual LSM hook returning a
1 will cause the LSM hook processing to exit early, potentially
skipping a LSM.  Thankfully, with the exception of the BPF LSM, none
of the LSMs which currently register inode xattr hooks should end up
returning a value of 1, and in the BPF LSM case, with the BPF LSM hooks
executing last there should be no real harm in stopping processing of
the LSM hooks.  However, the reliance on the individual LSMs to either
call the capability hooks themselves, or signal the LSM with a return
value of 1, is fragile and relies on a specific set of LSMs being
enabled.  This patch is an effort to resolve, or minimize, these
issues.

Before we discuss the solution, there are a few observations and
considerations that we need to take into account:
* BPF LSM registers an implementation for every LSM hook, and that
  implementation simply returns the hook's default return value, a
  0 in this case.  We want to ensure that the default BPF LSM behavior
  results in the capability checks being called.
* SELinux and Smack do not expect the traditional capability checks
  to be applied to the xattrs that they "own".
* SELinux and Smack are currently written in such a way that the
  xattr capability checks happen before any additional LSM specific
  access control checks.  SELinux does apply SELinux specific access
  controls to all xattrs, even those not "owned" by SELinux.
* IMA and EVM also register xattr hooks but assume that the LSM layer
  and specific LSMs have already authorized the basic xattr operation.

In order to ensure we perform the capability based access controls
before the individual LSM access controls, perform only one capability
access control check for each operation, and clarify the logic around
applying the capability controls, we need a mechanism to determine if
any of the enabled LSMs "own" a particular xattr and want to take
responsibility for controlling access to that xattr.  The solution in
this patch is to create a new LSM hook, 'inode_xattr_skipcap', that is
not exported to the rest of the kernel via a security_XXX() function,
but is used by the LSM layer to determine if a LSM wants to control
access to a given xattr and avoid the traditional capability controls.
Registering an inode_xattr_skipcap hook is optional, if a LSM declines
to register an implementation, or uses an implementation that simply
returns the default value (0), there is no effect as the LSM continues
to enforce the capability based controls (unless another LSM takes
ownership of the xattr).  If none of the LSMs signal that the
capability checks should be skipped, the capability check is performed
and if access is granted the individual LSM xattr access control hooks
are executed, keeping with the DAC-before-LSM convention.

Cc: stable@vger.kernel.org
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

Copying up xattrs is solely based on the security xattr name. For finer
granularity add a dentry parameter to the security_inode_copy_up_xattr
hook definition, allowing decisions to be based on the xattr content as
well.

Co-developed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Acked-by: Amir Goldstein <amir73il@gmail.com>
Acked-by: Paul Moore <paul@paul-moore.com> (LSM,SELinux)
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

Commit 08abce60 ("security: Introduce path_post_mknod hook")
introduced security_path_post_mknod(), to replace the IMA-specific call
to ima_post_path_mknod().

For symmetry with security_path_mknod(), security_path_post_mknod() was
called after a successful mknod operation, for any file type, rather
than only for regular files at the time there was the IMA call.

However, as reported by VFS maintainers, successful mknod operation does
not mean that the dentry always has an inode attached to it (for
example, not for FIFOs on a SAMBA mount).

If that condition happens, the kernel crashes when
security_path_post_mknod() attempts to verify if the inode associated to
the dentry is private.

Move security_path_post_mknod() where the ima_post_path_mknod() call was,
which is obviously correct from IMA/EVM perspective. IMA/EVM are the only
in-kernel users, and only need to inspect regular files.

Reported-by: Steve French <smfrench@gmail.com>
Closes: https://lore.kernel.org/linux-kernel/CAH2r5msAVzxCUHHG8VKrMPUKQHmBpE6K9_vjhgDa1uAvwx4ppw@mail.gmail.com/


Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Fixes: 08abce60 ("security: Introduce path_post_mknod hook")
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Passing a NULL buffer into the lsm_get_self_attr() syscall is a valid
way to quickly determine the minimum size of the buffer needed to for
the syscall to return all of the LSM attributes to the caller.
Unfortunately we/I broke that behavior in commit d7cf3412
("lsm: consolidate buffer size handling into lsm_fill_user_ctx()")
such that it returned an error to the caller; this patch restores the
original desired behavior of using the NULL buffer as a quick way to
correctly size the attribute buffer.

Cc: stable@vger.kernel.org
Fixes: d7cf3412 ("lsm: consolidate buffer size handling into lsm_fill_user_ctx()")
Signed-off-by: Paul Moore <paul@paul-moore.com>

Change the size parameters in lsm_list_modules(), lsm_set_self_attr()
and lsm_get_self_attr() from size_t to u32. This avoids the need to
have different interfaces for 32 and 64 bit systems.

Cc: stable@vger.kernel.org
Fixes: a04a1198 ("LSM: syscalls for current process attributes")
Fixes: ad4aff9e ("LSM: Create lsm_list_modules system call")
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reported-and-reviewed-by: Dmitry V. Levin <ldv@strace.io>
[PM: subject and metadata tweaks, syscall.h fixes]
Signed-off-by: Paul Moore <paul@paul-moore.com>

Change the definition of call_int_hook() to treat LSM_RET_DEFAULT(...)
as the "continue" value instead of 0. To further simplify this macro,
also drop the IRC argument and replace it with LSM_RET_DEFAULT(...).

After this the macro can be used in a couple more hooks, where similar
logic is currently open-coded. At the same time, some other existing
call_int_hook() users now need to be open-coded, but overall it's still
a net simplification.

There should be no functional change resulting from this patch.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: merge fuzz due to other hook changes, tweaks from list discussion]
Signed-off-by: Paul Moore <paul@paul-moore.com>

This commit fixes several typos in comment headers in security/security.c
where "Check is" should be "Check if".

Signed-off-by: Pairman Guo <pairmanxlr@gmail.com>
[PM: subject line tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>

Since now IMA and EVM use their own integrity metadata, it is safe to
remove the 'integrity' LSM, with its management of integrity metadata.

Keep the iint.c file only for loading IMA and EVM keys at boot, and for
creating the integrity directory in securityfs (we need to keep it for
retrocompatibility reasons).

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
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>

Define a new structure for EVM-specific metadata, called evm_iint_cache,
and embed it in the inode security blob. Introduce evm_iint_inode() to
retrieve metadata, and register evm_inode_alloc_security() for the
inode_alloc_security LSM hook, to initialize the structure (before
splitting metadata, this task was done by iint_init_always()).

Keep the non-NULL checks after calling evm_iint_inode() except in
evm_inode_alloc_security(), to take into account inodes for which
security_inode_alloc() was not called. When using shared metadata,
obtaining a NULL pointer from integrity_iint_find() meant that the file
wasn't in the IMA policy. Now, because IMA and EVM use disjoint metadata,
the EVM status has to be stored for every inode regardless of the IMA
policy.

Given that from now on EVM relies on its own metadata, remove the iint
parameter from evm_verifyxattr(). Also, directly retrieve the iint in
evm_verify_hmac(), called by both evm_verifyxattr() and
evm_verify_current_integrity(), since now there is no performance penalty
in retrieving EVM metadata (constant time).

Replicate the management of the IMA_NEW_FILE flag, by introducing
evm_post_path_mknod() and evm_file_release() to respectively set and clear
the newly introduced flag EVM_NEW_FILE, at the same time IMA does. Like for
IMA, select CONFIG_SECURITY_PATH when EVM is enabled, to ensure that files
are marked as new.

Unlike ima_post_path_mknod(), evm_post_path_mknod() cannot check if a file
must be appraised. Thus, it marks all affected files. Also, it does not
clear EVM_NEW_FILE depending on i_version, but that is not a problem
because IMA_NEW_FILE is always cleared when set in ima_check_last_writer().

Move the EVM-specific flag EVM_IMMUTABLE_DIGSIG to
security/integrity/evm/evm.h, since that definition is now unnecessary in
the common integrity layer.

Finally, switch to the LSM reservation mechanism for the EVM xattr, and
consequently decrement by one the number of xattrs to allocate in
security_inode_init_security().

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
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>

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>

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>

Move hardcoded IMA function calls (not appraisal-specific functions) from
various places in the kernel to the LSM infrastructure, by introducing a
new LSM named 'ima' (at the end of the LSM list and always enabled like
'integrity').

Having IMA before EVM in the Makefile is sufficient to preserve the
relative order of the new 'ima' LSM in respect to the upcoming 'evm' LSM,
and thus the order of IMA and EVM function calls as when they were
hardcoded.

Make moved functions as static (except ima_post_key_create_or_update(),
which is not in ima_main.c), and register them as implementation of the
respective hooks in the new function init_ima_lsm().

Select CONFIG_SECURITY_PATH, to ensure that the path-based LSM hook
path_post_mknod is always available and ima_post_path_mknod() is always
executed to mark files as new, as before the move.

A slight difference is that IMA and EVM functions registered for the
inode_post_setattr, inode_post_removexattr, path_post_mknod,
inode_post_create_tmpfile, inode_post_set_acl and inode_post_remove_acl
won't be executed for private inodes. Since those inodes are supposed to be
fs-internal, they should not be of interest to IMA or EVM. The S_PRIVATE
flag is used for anonymous inodes, hugetlbfs, reiserfs xattrs, XFS scrub
and kernel-internal tmpfs files.

Conditionally register ima_post_key_create_or_update() if
CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS is enabled. Also, conditionally register
ima_kernel_module_request() if CONFIG_INTEGRITY_ASYMMETRIC_KEYS is enabled.

Finally, add the LSM_ID_IMA case in lsm_list_modules_test.c.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Acked-by: Chuck Lever <chuck.lever@oracle.com>
Acked-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>

In preparation for removing the 'integrity' LSM, move
integrity_kernel_module_request() to IMA, and rename it to
ima_kernel_module_request(). Rewrite the function documentation, to explain
better what the problem is.

Compile it conditionally if CONFIG_INTEGRITY_ASYMMETRIC_KEYS is enabled,
and call it from security.c (removed afterwards with the move of IMA to the
LSM infrastructure).

Adding this hook cannot be avoided, since IMA has no control on the flags
passed to crypto_alloc_sig() in public_key_verify_signature(), and thus
cannot pass CRYPTO_NOLOAD, which solved the problem for EVM hashing with
commit e2861fa7 ("evm: Don't deadlock if a crypto algorithm is
unavailable").

EVM alone does not need to implement this hook, first because there is no
mutex to deadlock, and second because even if it had it, there should be a
recursive call. However, since verification from EVM can be initiated only
by setting inode metadata, deadlock would occur if modprobe would do the
same while loading a kernel module (which is unlikely).

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: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

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

Depending on policy, IMA measures the key content after creation or update,
so that remote verifiers are aware of the operation.

Other LSMs could similarly take some action after successful key creation
or update.

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>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

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

At inode_remove_acl hook, EVM verifies the file's existing HMAC value. At
inode_post_remove_acl, EVM re-calculates the file's HMAC with the passed
POSIX ACL removed and other file metadata.

Other LSMs could similarly take some action after successful POSIX ACL
removal.

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>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Paul Moore <paul@paul-moore.com>

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

At inode_set_acl hook, EVM verifies the file's existing HMAC value. At
inode_post_set_acl, EVM re-calculates the file's HMAC based on the modified
POSIX ACL and other file metadata.

Other LSMs could similarly take some action after successful POSIX ACL
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>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Paul Moore <paul@paul-moore.com>

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

As temp files can be made persistent, treat new temp files like other new
files, so that the file hash is calculated and stored in the security
xattr.

LSMs could also take some action after temp files have been created.

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

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

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

IMA-appraisal requires all existing files in policy to have a file
hash/signature stored in security.ima. An exception is made for empty files
created by mknod, by tagging them as new files.

LSMs could also take some action after files are created.

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

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

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

IMA calculates at file close the new digest of the file content and writes
it to security.ima, so that appraisal at next file access succeeds.

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

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

In preparation to move IMA and EVM to the LSM infrastructure, introduce the
file_post_open hook. Also, export security_file_post_open() for NFS.

Based on policy, IMA calculates the digest of the file content and
extends the TPM with the digest, verifies the file's integrity based on
the digest, and/or includes the file digest in the audit log.

LSMs could similarly take action depending on the file content and the
access mask requested with open().

The new hook returns a value and can cause the open to be aborted.

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

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

At inode_removexattr hook, EVM verifies the file's existing HMAC value. At
inode_post_removexattr, EVM re-calculates the file's HMAC with the passed
xattr removed and other file metadata.

Other LSMs could similarly take some action after successful xattr removal.

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>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Paul Moore <paul@paul-moore.com>

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>

Add the idmap parameter to the definition, so that evm_inode_setattr() can
be registered as this hook implementation.

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

Change evm_inode_post_setxattr() definition, so that it can be registered
as implementation of the inode_post_setxattr hook.

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: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

Change evm_inode_setxattr() definition, so that it can be registered as
implementation of the inode_setxattr hook.

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: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

Change ima_inode_removexattr() definition, so that it can be registered as
implementation of the inode_removexattr hook.

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>

Change ima_inode_setxattr() definition, so that it can be registered as
implementation of the inode_setxattr hook.

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: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

Change ima_file_mprotect() definition, so that it can be registered
as implementation of the file_mprotect hook.

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>

security_setselfattr() has an integer overflow bug that leads to
out-of-bounds access when userspace provides bogus input:
`lctx->ctx_len + sizeof(*lctx)` is checked against `lctx->len` (and,
redundantly, also against `size`), but there are no checks on
`lctx->ctx_len`.
Therefore, userspace can provide an `lsm_ctx` with `->ctx_len` set to a
value between `-sizeof(struct lsm_ctx)` and -1, and this bogus `->ctx_len`
will then be passed to an LSM module as a buffer length, causing LSM
modules to perform out-of-bounds accesses.

The following reproducer will demonstrate this under ASAN (if AppArmor is
loaded as an LSM):

```

struct lsm_ctx {
  uint64_t id;
  uint64_t flags;
  uint64_t len;
  uint64_t ctx_len;
  char ctx[];
};

int main(void) {
  size_t size = sizeof(struct lsm_ctx);
  struct lsm_ctx *ctx = malloc(size);
  ctx->id = 104/*LSM_ID_APPARMOR*/;
  ctx->flags = 0;
  ctx->len = size;
  ctx->ctx_len = -sizeof(struct lsm_ctx);
  syscall(
    460/*__NR_lsm_set_self_attr*/,
    /*attr=*/  100/*LSM_ATTR_CURRENT*/,
    /*ctx=*/   ctx,
    /*size=*/  size,
    /*flags=*/ 0
  );
}
```

Fixes: a04a1198 ("LSM: syscalls for current process attributes")
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: subj tweak, removed ref to ASAN splat that isn't included]
Signed-off-by: Paul Moore <paul@paul-moore.com>

For these hooks the true "neutral" value is -EOPNOTSUPP, which is
currently what is returned when no LSM provides this hook and what LSMs
return when there is no security context set on the socket. Correct the
value in <linux/lsm_hooks.h> and adjust the dispatch functions in
security/security.c to avoid issues when the BPF LSM is enabled.

Cc: stable@vger.kernel.org
Fixes: 98e828a0 ("security: Refactor declaration of LSM hooks")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
[PM: subject line tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>

The inode_getsecctx LSM hook has previously been corrected to have
-EOPNOTSUPP instead of 0 as the default return value to fix BPF LSM
behavior. However, the call_int_hook()-generated loop in
security_inode_getsecctx() was left treating 0 as the neutral value, so
after an LSM returns 0, the loop continues to try other LSMs, and if one
of them returns a non-zero value, the function immediately returns with
said value. So in a situation where SELinux and the BPF LSMs registered
this hook, -EOPNOTSUPP would be incorrectly returned whenever SELinux
returned 0.

Fix this by open-coding the call_int_hook() loop and making it use the
correct LSM_RET_DEFAULT() value as the neutral one, similar to what
other hooks do.

Cc: stable@vger.kernel.org
Reported-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Link: https://lore.kernel.org/selinux/CAEjxPJ4ev-pasUwGx48fDhnmjBnq_Wh90jYPwRQRAqXxmOKD4Q@mail.gmail.com/
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2257983


Fixes: b36995b8 ("lsm: fix default return value for inode_getsecctx")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: subject line tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>

Wire up bpf_token_create and bpf_token_free LSM hooks, which allow to
allocate LSM security blob (we add `void *security` field to struct
bpf_token for that), but also control who can instantiate BPF token.
This follows existing pattern for BPF map and BPF prog.

Also add security_bpf_token_allow_cmd() and security_bpf_token_capable()
LSM hooks that allow LSM implementation to control and negate (if
necessary) BPF token's delegation of a specific bpf_cmd and capability,
respectively.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Link: https://lore.kernel.org/bpf/20240124022127.2379740-12-andrii@kernel.org

Similarly to bpf_prog_alloc LSM hook, rename and extend bpf_map_alloc
hook into bpf_map_create, taking not just struct bpf_map, but also
bpf_attr and bpf_token, to give a fuller context to LSMs.

Unlike bpf_prog_alloc, there is no need to move the hook around, as it
currently is firing right before allocating BPF map ID and FD, which
seems to be a sweet spot.

But like bpf_prog_alloc/bpf_prog_free combo, make sure that bpf_map_free
LSM hook is called even if bpf_map_create hook returned error, as if few
LSMs are combined together it could be that one LSM successfully
allocated security blob for its needs, while subsequent LSM rejected BPF
map creation. The former LSM would still need to free up LSM blob, so we
need to ensure security_bpf_map_free() is called regardless of the
outcome.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Link: https://lore.kernel.org/bpf/20240124022127.2379740-11-andrii@kernel.org

Based on upstream discussion ([0]), rework existing
bpf_prog_alloc_security LSM hook. Rename it to bpf_prog_load and instead
of passing bpf_prog_aux, pass proper bpf_prog pointer for a full BPF
program struct. Also, we pass bpf_attr union with all the user-provided
arguments for BPF_PROG_LOAD command.  This will give LSMs as much
information as we can basically provide.

The hook is also BPF token-aware now, and optional bpf_token struct is
passed as a third argument. bpf_prog_load LSM hook is called after
a bunch of sanity checks were performed, bpf_prog and bpf_prog_aux were
allocated and filled out, but right before performing full-fledged BPF
verification step.

bpf_prog_free LSM hook is now accepting struct bpf_prog argument, for
consistency. SELinux code is adjusted to all new names, types, and
signatures.

Note, given that bpf_prog_load (previously bpf_prog_alloc) hook can be
used by some LSMs to allocate extra security blob, but also by other
LSMs to reject BPF program loading, we need to make sure that
bpf_prog_free LSM hook is called after bpf_prog_load/bpf_prog_alloc one
*even* if the hook itself returned error. If we don't do that, we run
the risk of leaking memory. This seems to be possible today when
combining SELinux and BPF LSM, as one example, depending on their
relative ordering.

Also, for BPF LSM setup, add bpf_prog_load and bpf_prog_free to
sleepable LSM hooks list, as they are both executed in sleepable
context. Also drop bpf_prog_load hook from untrusted, as there is no
issue with refcount or anything else anymore, that originally forced us
to add it to untrusted list in c0c852dd ("bpf: Do not mark certain LSM
hook arguments as trusted"). We now trigger this hook much later and it
should not be an issue anymore.

  [0] https://lore.kernel.org/bpf/9fe88aef7deabbe87d3fc38c4aea3c69.paul@paul-moore.com/



Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Link: https://lore.kernel.org/bpf/20240124022127.2379740-10-andrii@kernel.org

Some ioctl commands do not require ioctl permission, but are routed to
other permissions such as FILE_GETATTR or FILE_SETATTR. This routing is
done by comparing the ioctl cmd to a set of 64-bit flags (FS_IOC_*).

However, if a 32-bit process is running on a 64-bit kernel, it emits
32-bit flags (FS_IOC32_*) for certain ioctl operations. These flags are
being checked erroneously, which leads to these ioctl operations being
routed to the ioctl permission, rather than the correct file
permissions.

This was also noted in a RED-PEN finding from a while back -
"/* RED-PEN how should LSM module know it's handling 32bit? */".

This patch introduces a new hook, security_file_ioctl_compat(), that is
called from the compat ioctl syscall. All current LSMs have been changed
to support this hook.

Reviewing the three places where we are currently using
security_file_ioctl(), it appears that only SELinux needs a dedicated
compat change; TOMOYO and SMACK appear to be functional without any
change.

Cc: stable@vger.kernel.org
Fixes: 0b24dcb7 ("Revert "selinux: simplify ioctl checking"")
Signed-off-by: Alfred Piccioni <alpic@google.com>
Reviewed-by: Stephen Smalley <stephen.smalley.work@gmail.com>
[PM: subject tweak, line length fixes, and alignment corrections]
Signed-off-by: Paul Moore <paul@paul-moore.com>

The security.evm HMAC and the original file signatures contain
filesystem specific data.  As a result, the HMAC and signature
are not the same on the stacked and backing filesystems.

Don't copy up 'security.evm'.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

This patch includes the following revert (one  conflicting BPF FS
patch and three token patch sets, represented by merge commits):
  - revert 0f5d5454 "Merge branch 'bpf-fs-mount-options-parsing-follow-ups'";
  - revert 750e7857 "bpf: Support uid and gid when mounting bpffs";
  - revert 73376328 "Merge branch 'bpf-token-support-in-libbpf-s-bpf-object'";
  - revert c35919dc "Merge branch 'bpf-token-and-bpf-fs-based-delegation'".

Link: https://lore.kernel.org/bpf/CAHk-=wg7JuFYwGy=GOMbRCtOL+jwSQsdUaBsRWkDVYbxipbM5A@mail.gmail.com


Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

In preparation for pre-content permission events with file access range,
move fsnotify_file_perm() hook out of security_file_permission() and into
the callers.

Callers that have the access range information call the new hook
fsnotify_file_area_perm() with the access range.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231212094440.250945-6-amir73il@gmail.com


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

We would like to make changes to the fsnotify access permission hook -
add file range arguments and add the pre modify event.

In preparation for these changes, split the fsnotify_perm() hook into
fsnotify_open_perm() and fsnotify_file_perm().

This is needed for fanotify "pre content" events.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231212094440.250945-4-amir73il@gmail.com


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