kernel/git/stable/linux-stable.git/security/smack, branch linux-rolling-lts

smack: restrict smackfs/{direct,mapped} values to 0-255

2026-09-14T11:34:23+00:00

[ Upstream commit a7c44fd9f80e37763acf9cd3c87a58058d206427 ] Both smackfs/direct and smackfs/mapped incorrectly accept the full range of integer values. For example: # cd /sys/fs/smackfs/ # cat direct ; echo 250 # cat cipso2 @ 250/2 _ 250/2,4,5,6,7,8 * 250/3,5,7 ^ 250/2,4,5,6,7 ? 250/3,4,5,6,7,8 # echo -1234 >direct ; cat direct ; echo -1234 # cat cipso2 @ -1234/2 _ -1234/2,4,5,6,7,8 * -1234/3,5,7 ^ -1234/2,4,5,6,7 ? -1234/3,4,5,6,7,8 # I noticed two things regarding this: 1) sensitivity levels are truncated to 8 bits when labeling outgoing packets (0x2e = 46 for the -1234 example above) 2) the reverse process fails: incoming packets with sensitivity level 46 do not match these smackfs/cipso2 entries. Even observation (1) on its own warrants a fix. This patch restricts smackfs/direct and smackfs/mapped accepted values to the 0-255 range. Fixes: e114e473771c ("Smack: Simplified Mandatory Access Control Kernel") Signed-off-by: Konstantin Andreev Signed-off-by: Casey Schaufler Signed-off-by: Sasha Levin

smack: deduplicate smackfs/{direct,mapped} file_operations

2026-09-14T11:34:23+00:00

[ Upstream commit 577dc3b6a8cf200e6e27b2d9967cac14a1fed2f3 ] The file_operations for smackfs/direct and smackfs/mapped are identical up to a textual replacement of "direct" with "mapped" This patch combines two instances of file_operations into one, handling both files. Fixes: f7112e6c9abf ("Smack: allow for significantly longer Smack labels v4") Signed-off-by: Konstantin Andreev Signed-off-by: Casey Schaufler Signed-off-by: Sasha Levin

smack: simplify write handlers of sysfs entries

2026-09-14T11:34:23+00:00

[ Upstream commit b78fede1c69a090d377bf80417ce1f7f7f314534 ] Use the convenient 'kstrto{u,s}32_from_user()' to simplify write handlers of /smack/{doi,direct,mapped,logging,ptrace} sysfs entries. Signed-off-by: Dmitry Antipov Signed-off-by: Casey Schaufler Stable-dep-of: 577dc3b6a8cf ("smack: deduplicate smackfs/{direct,mapped} file_operations") Signed-off-by: Sasha Levin

smack: fix incorrect task context in smack_msg_queue_msgrcv

2026-09-14T11:34:22+00:00

[ Upstream commit fba3d32825f4bbc8e20f0cdc3b14df57965b8fe5 ] The smack_msg_queue_msgrcv() function incorrectly checks the permissions of the 'current' task instead of the 'target' task. In the msgsnd() syscall path, if a receiver is already waiting, the pipelined_send() optimization is used to push the message directly to the receiver task: ipc/msg.c`pipelined_send(): ` smp_store_release(&msr->r_msg, msg) In this case, the 'sender' (current) task performs the check on behalf of the 'receiver' task (msr->r_tsk, passed as the 'target' parameter): ipc/msg.c`pipelined_send(): ` security_msg_queue_msgrcv(,, target := msr->r_tsk,,) However, smack_msg_queue_msgrcv() ignores the 'target' and checks 'current': smack_msg_queue_msgrcv(…) ` smk_curacc_msq(isp, MAY_READWRITE); // current task 'current' MAY satisfy smack_msg_queue_msgrcv r/w requirement, but 'target' (the receiver task) might NOT; as a result, an unauthorized receiver gets the message, violating MAC policy. Test: 1) create a sysv message queue with label “foo” 2) echo "bar foo r" >/smack/load2 3) msgrcv(,,,0,MSG_NOERROR) in "bar"-labeled task. The task is waiting for the messages ... 4) msgsnd() from a "foo"-labeled task: "bar"-labeled task gets the message. This patch fixes the issue by checking permission on the 'target' task instead of 'current'. (2008-02-04, Casey Schaufler) Fixes: e114e473771c ("Smack: Simplified Mandatory Access Control Kernel") Signed-off-by: Konstantin Andreev Signed-off-by: Casey Schaufler Signed-off-by: Sasha Levin

Smack: Fix error in capability bypass

2026-09-14T11:34:21+00:00

[ Upstream commit b2faddc13112489f8f11eb40b9456db8c1b58362 ] A bug in smack_inode_xattr_skipcap() was introduced in the inode capability handling. The strncmp guard at the top of the function is coded backwards, resulting in consistently incorrect results. Correct the check, and the code functions as it should. The error manifests as requiring CAP_SYS_ADMIN as well as CAP_MAC_ADMIN to change an inode's MAC attributes. Fixes: 61df7b828204 ("lsm: fixup the inode xattr capability handling") Reported-by: Bumjin Im Signed-off-by: Casey Schaufler Signed-off-by: Sasha Levin

smack: fix cred UAF in smack_file_send_sigiotask()

2026-09-07T15:22:59+00:00

commit fedc88e38ce979a720cd2de042578cb5df3dc8de upstream. When inspecting the credentials of another task, objective credentials (->real_cred, accessed with __task_cred()) must always be used. Accessing ->cred on a non-current task is forbidden unless that task is being created or destroyed; a task is allowed to change its own ->cred pointer with no synchronization, and changing ->cred should only affect the current syscall. smack_file_send_sigiotask() was accessing both sets of credentials: First tsk->cred, then __task_cred(tsk). Fix it, always access the objective credentials here. I have tested that this bug can lead to a KASAN-reported UAF of struct cred in smack_file_send_sigiotask(), and that this fix prevents the race. Cc: stable@vger.kernel.org Signed-off-by: Jann Horn Signed-off-by: Casey Schaufler Signed-off-by: Greg Kroah-Hartman

smack: /smack/doi: accept previously used values

2026-02-26T22:59:11+00:00

[ Upstream commit 33d589ed60ae433b483761987b85e0d24e54584e ] Writing to /smack/doi a value that has ever been written there in the past disables networking for non-ambient labels. E.g. # cat /smack/doi 3 # netlabelctl -p cipso list Configured CIPSO mappings (1) DOI value : 3 mapping type : PASS_THROUGH # netlabelctl -p map list Configured NetLabel domain mappings (3) domain: "_" (IPv4) protocol: UNLABELED domain: DEFAULT (IPv4) protocol: CIPSO, DOI = 3 domain: DEFAULT (IPv6) protocol: UNLABELED # cat /smack/ambient _ # cat /proc/$$/attr/smack/current _ # ping -c1 10.1.95.12 64 bytes from 10.1.95.12: icmp_seq=1 ttl=64 time=0.964 ms # echo foo >/proc/$$/attr/smack/current # ping -c1 10.1.95.12 64 bytes from 10.1.95.12: icmp_seq=1 ttl=64 time=0.956 ms unknown option 86 # echo 4 >/smack/doi # echo 3 >/smack/doi !> [ 214.050395] smk_cipso_doi:691 cipso add rc = -17 # echo 3 >/smack/doi !> [ 249.402261] smk_cipso_doi:678 remove rc = -2 !> [ 249.402261] smk_cipso_doi:691 cipso add rc = -17 # ping -c1 10.1.95.12 !!> ping: 10.1.95.12: Address family for hostname not supported # echo _ >/proc/$$/attr/smack/current # ping -c1 10.1.95.12 64 bytes from 10.1.95.12: icmp_seq=1 ttl=64 time=0.617 ms This happens because Smack keeps decommissioned DOIs, fails to re-add them, and consequently refuses to add the “default” domain map: # netlabelctl -p cipso list Configured CIPSO mappings (2) DOI value : 3 mapping type : PASS_THROUGH DOI value : 4 mapping type : PASS_THROUGH # netlabelctl -p map list Configured NetLabel domain mappings (2) domain: "_" (IPv4) protocol: UNLABELED !> (no ipv4 map for default domain here) domain: DEFAULT (IPv6) protocol: UNLABELED Fix by clearing decommissioned DOI definitions and serializing concurrent DOI updates with a new lock. Also: - allow /smack/doi to live unconfigured, since adding a map (netlbl_cfg_cipsov4_map_add) may fail. CIPSO_V4_DOI_UNKNOWN(0) indicates the unconfigured DOI - add new DOI before removing the old default map, so the old map remains if the add fails (2008-02-04, Casey Schaufler) Fixes: e114e473771c ("Smack: Simplified Mandatory Access Control Kernel") Signed-off-by: Konstantin Andreev Signed-off-by: Casey Schaufler Signed-off-by: Sasha Levin

smack: /smack/doi must be > 0

2026-02-26T22:59:11+00:00

[ Upstream commit 19c013e1551bf51e1493da1270841d60e4fd3f15 ] /smack/doi allows writing and keeping negative doi values. Correct values are 0 < doi <= (max 32-bit positive integer) (2008-02-04, Casey Schaufler) Fixes: e114e473771c ("Smack: Simplified Mandatory Access Control Kernel") Signed-off-by: Konstantin Andreev Signed-off-by: Casey Schaufler Signed-off-by: Sasha Levin

smack: fix bug: setting task label silently ignores input garbage

2025-12-18T13:02:25+00:00

[ Upstream commit 674e2b24791cbe8fd5dc8a0aed4cb4404fcd2028 ] This command: # echo foo/bar >/proc/$$/attr/smack/current gives the task a label 'foo' w/o indication that label does not match input. Setting the label with lsm_set_self_attr() syscall behaves identically. This occures because: 1) smk_parse_smack() is used to convert input to a label 2) smk_parse_smack() takes only that part from the beginning of the input that looks like a label. 3) `/' is prohibited in labels, so only "foo" is taken. (2) is by design, because smk_parse_smack() is used for parsing strings which are more than just a label. Silent failure is not a good thing, and there are two indicators that this was not done intentionally: (size >= SMK_LONGLABEL) ~> invalid clause at the beginning of the do_setattr() and the "Returns the length of the smack label" claim in the do_setattr() description. So I fixed this by adding one tiny check: the taken label length == input length. Since input length is now strictly controlled, I changed the two ways of setting label smack_setselfattr(): lsm_set_self_attr() syscall smack_setprocattr(): > /proc/.../current to accommodate the divergence in what they understand by "input length": smack_setselfattr counts mandatory \0 into input length, smack_setprocattr does not. smack_setprocattr allows various trailers after label Related changes: * fixed description for smk_parse_smack * allow unprivileged tasks validate label syntax. * extract smk_parse_label_len() from smk_parse_smack() so parsing may be done w/o string allocation. * extract smk_import_valid_label() from smk_import_entry() to avoid repeated parsing. * smk_parse_smack(): scan null-terminated strings for no more than SMK_LONGLABEL(256) characters * smack_setselfattr(): require struct lsm_ctx . flags == 0 to reserve them for future. Fixes: e114e473771c ("Smack: Simplified Mandatory Access Control Kernel") Signed-off-by: Konstantin Andreev Signed-off-by: Casey Schaufler Signed-off-by: Sasha Levin

smack: fix bug: unprivileged task can create labels

2025-12-18T13:02:25+00:00

[ Upstream commit c147e13ea7fe9f118f8c9ba5e96cbd644b00d6b3 ] If an unprivileged task is allowed to relabel itself (/smack/relabel-self is not empty), it can freely create new labels by writing their names into own /proc/PID/attr/smack/current This occurs because do_setattr() imports the provided label in advance, before checking "relabel-self" list. This change ensures that the "relabel-self" list is checked before importing the label. Fixes: 38416e53936e ("Smack: limited capability for changing process label") Signed-off-by: Konstantin Andreev Signed-off-by: Casey Schaufler Signed-off-by: Sasha Levin