linux-stable.git/security/integrity, branch linux-6.10.y

lsm: add the inode_free_security_rcu() LSM implementation hook

2024-10-04T14:33:42+00:00

commit 63dff3e48871b0583be5032ff8fb7260c349a18c upstream.

The LSM framework has an existing inode_free_security() hook which
is used by LSMs that manage state associated with an inode, but
due to the use of RCU to protect the inode, special care must be
taken to ensure that the LSMs do not fully release the inode state
until it is safe from a RCU perspective.

This patch implements a new inode_free_security_rcu() implementation
hook which is called when it is safe to free the LSM's internal inode
state.  Unfortunately, this new hook does not have access to the inode
itself as it may already be released, so the existing
inode_free_security() hook is retained for those LSMs which require
access to the inode.

Cc: stable@vger.kernel.org
Reported-by: syzbot+5446fbf332b0602ede0b@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/r/00000000000076ba3b0617f65cc8@google.com
Signed-off-by: Paul Moore 
Signed-off-by: Greg Kroah-Hartman

Merge tag 'integrity-v6.10-fix' of ssh://ra.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity

2024-07-05T23:21:54+00:00

Pull integrity fix from Mimi Zohar:
 "A single bug fix to properly remove all of the securityfs IMA
  measurement lists"

* tag 'integrity-v6.10-fix' of ssh://ra.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
  ima: fix wrong zero-assignment during securityfs dentry remove

ima: Avoid blocking in RCU read-side critical section

2024-06-13T18:26:50+00:00

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 c7423dbdbc9e ("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: c7423dbdbc9e ("ima: Handle -ESTALE returned by ima_filter_rule_match()")
Cc: stable@vger.kernel.org
Signed-off-by: GUO Zihua 
Acked-by: John Johansen 
Reviewed-by: Mimi Zohar 
Reviewed-by: Casey Schaufler 
[PM: fixed missing comment, long lines, !CONFIG_IMA_LSM_RULES case]
Signed-off-by: Paul Moore

ima: fix wrong zero-assignment during securityfs dentry remove

2024-06-03T20:37:22+00:00

In case of error during ima_fs_init() all the dentry already created
are removed. {ascii, binary}_securityfs_measurement_lists are freed
calling for each array the remove_securityfs_measurement_lists(). This
function, at the end, assigns to zero the securityfs_measurement_list_count.
This causes during the second call of remove_securityfs_measurement_lists()
to leave the dentry of the array pending, not removing them correctly,
because the securityfs_measurement_list_count is already zero.

Move the securityfs_measurement_list_count = 0 after the two
remove_securityfs_measurement_lists() calls to correctly remove all the
dentry already allocated.

Fixes: 9fa8e7625008 ("ima: add crypto agility support for template-hash algorithm")
Signed-off-by: Enrico Bravi 
Reviewed-by: Roberto Sassu 
Signed-off-by: Mimi Zohar

ima: add crypto agility support for template-hash algorithm

2024-04-12T13:59:04+00:00

The template hash showed by the ascii_runtime_measurements and
binary_runtime_measurements is the one calculated using sha1 and there is
no possibility to change this value, despite the fact that the template
hash is calculated using the hash algorithms corresponding to all the PCR
banks configured in the TPM.

Add the support to retrieve the ima log with the template data hash
calculated with a specific hash algorithm.
Add a new file in the securityfs ima directory for each hash algo
configured in a PCR bank of the TPM. Each new file has the name with
the following structure:

        {binary, ascii}_runtime_measurements_

Legacy files are kept, to avoid breaking existing applications, but as
symbolic links which point to {binary, ascii}_runtime_measurements_sha1
files. These two files are created even if a TPM chip is not detected or
the sha1 bank is not configured in the TPM.

As example, in the case a TPM chip is present and sha256 is the only
configured PCR bank, the listing of the securityfs ima directory is the
following:

lr--r--r-- [...] ascii_runtime_measurements -> ascii_runtime_measurements_sha1
-r--r----- [...] ascii_runtime_measurements_sha1
-r--r----- [...] ascii_runtime_measurements_sha256
lr--r--r-- [...] binary_runtime_measurements -> binary_runtime_measurements_sha1
-r--r----- [...] binary_runtime_measurements_sha1
-r--r----- [...] binary_runtime_measurements_sha256
--w------- [...] policy
-r--r----- [...] runtime_measurements_count
-r--r----- [...] violations

Signed-off-by: Enrico Bravi 
Signed-off-by: Silvia Sisinni 
Reviewed-by: Roberto Sassu 
Signed-off-by: Mimi Zohar

evm: Rename is_unsupported_fs to is_unsupported_hmac_fs

2024-04-09T21:14:58+00:00

Rename is_unsupported_fs to is_unsupported_hmac_fs since now only HMAC is
unsupported.

Co-developed-by: Mimi Zohar 
Signed-off-by: Stefan Berger 
Signed-off-by: Mimi Zohar

fs: Rename SB_I_EVM_UNSUPPORTED to SB_I_EVM_HMAC_UNSUPPORTED

2024-04-09T21:14:58+00:00

Now that EVM supports RSA signatures for previously completely
unsupported filesystems rename the flag SB_I_EVM_UNSUPPORTED to
SB_I_EVM_HMAC_UNSUPPORTED to reflect that only HMAC is not supported.

Suggested-by: Amir Goldstein 
Suggested-by: Mimi Zohar 
Signed-off-by: Stefan Berger 
Acked-by: Amir Goldstein 
Signed-off-by: Mimi Zohar

evm: Enforce signatures on unsupported filesystem for EVM_INIT_X509

2024-04-09T21:14:57+00:00

Unsupported filesystems currently do not enforce any signatures. Add
support for signature enforcement of the "original" and "portable &
immutable" signatures when EVM_INIT_X509 is enabled.

The "original" signature type contains filesystem specific metadata.
Thus it cannot be copied up and verified. However with EVM_INIT_X509
and EVM_ALLOW_METADATA_WRITES enabled, the "original" file signature
may be written.

When EVM_ALLOW_METADATA_WRITES is not set or once it is removed from
/sys/kernel/security/evm by setting EVM_INIT_HMAC for example, it is not
possible to write or remove xattrs on the overlay filesystem.

This change still prevents EVM from writing HMAC signatures on
unsupported filesystem when EVM_INIT_HMAC is enabled.

Co-developed-by: Mimi Zohar 
Signed-off-by: Stefan Berger 
Signed-off-by: Mimi Zohar

ima: re-evaluate file integrity on file metadata change

2024-04-09T21:14:57+00:00

Force a file's integrity to be re-evaluated on file metadata change by
resetting both the IMA and EVM status flags.

Co-developed-by: Mimi Zohar 
Signed-off-by: Stefan Berger 
Signed-off-by: Mimi Zohar

evm: Store and detect metadata inode attributes changes

2024-04-09T21:14:57+00:00

On stacked filesystem the metadata inode may be different than the one
file data inode and therefore changes to it need to be detected
independently. Therefore, store the i_version, device number, and inode
number associated with the file metadata inode.

Implement a function to detect changes to the inode and if a change is
detected reset the evm_status. This function will be called by IMA when
IMA detects that the metadata inode is different from the file's inode.

Co-developed-by: Mimi Zohar 
Signed-off-by: Stefan Berger 
Signed-off-by: Mimi Zohar