kernel/git/stable/linux.git/security/landlock/fs.c, branch linux-7.2.y

Merge tag 'landlock-7.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux

2026-06-19T19:20:25+00:00

Pull landlock updates from Mickaël Salaün: "This adds new Landlock access rights to control UDP bind and connect/send operations, and a new "quiet" feature to mute specific specific audit logs (and other future observability events). A few commits also fix Landlock issues" * tag 'landlock-7.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux: (24 commits) selftests/landlock: Add tests for invalid use of quiet flag selftests/landlock: Add tests for quiet flag with scope selftests/landlock: Add tests for quiet flag with net rules selftests/landlock: Add tests for quiet flag with fs rules selftests/landlock: Replace hard-coded 16 with a constant samples/landlock: Add quiet flag support to sandboxer landlock: Suppress logging when quiet flag is present landlock: Add API support and docs for the quiet flags landlock: Add a place for flags to layer rules landlock: Add documentation for UDP support samples/landlock: Add sandboxer UDP access control selftests/landlock: Add tests for UDP send selftests/landlock: Add tests for UDP bind/connect landlock: Add UDP send+connect access control landlock: Add UDP bind() access control landlock: Fix unmarked concurrent access to socket family selftests/landlock: Explicitly disable audit in teardowns selftests/landlock: Test SCOPE_SIGNAL on the SIGIO/fowner pgid path landlock: Fix LANDLOCK_SCOPE_SIGNAL bypass on the SIGIO path landlock: Demonstrate best-effort allowed_access filtering ...

landlock: Suppress logging when quiet flag is present

2026-06-14T18:17:19+00:00

The quietness behaviour is as documented in the previous patch. For optional accesses, since the existing deny_masks can only store 2x4bit of layer index, with no way to represent "no layer", we need to either expand it or have another field to correctly handle quieting of those. This commit uses the latter approach - we add another field to store which optional access (of the 2) are covered by quiet rules in their respective layers as stored in deny_masks. Assisted-by: GitHub-Copilot:claude-opus-4.8 copilot-review Signed-off-by: Tingmao Wang Link: https://patch.msgid.link/2510a357a94183683eefc49917dcb2240d67be96.1781228815.git.m@maowtm.org [mic: Cosmetic fixes] Signed-off-by: Mickaël Salaün

landlock: Add API support and docs for the quiet flags

2026-06-14T18:17:19+00:00

Adds the UAPI for the quiet flags feature (but not the implementation yet). Even though currently LANDLOCK_ADD_RULE_QUIET only affects audit logging, in the future this can also be used as part of a supervisor mechanism, where it will also suppress denial notifications on a per-object basis. Thus the name is deliberately generic, as opposed to e.g. LANDLOCK_ADD_RULE_LOG_QUIET. According to pahole, even after adding the struct access_masks quiet_masks in struct landlock_hierarchy, the u32 log_* bitfield still only has a size of 2 bytes, so there's minimal wasted space. Assisted-by: GitHub-Copilot:claude-opus-4.8 Signed-off-by: Tingmao Wang [mic: Update date, fix comment formatting] Link: https://patch.msgid.link/031184748a8e74c0bb02f1fa13d7a3f10918c627.1781228815.git.m@maowtm.org Signed-off-by: Mickaël Salaün

landlock: Add a place for flags to layer rules

2026-06-14T18:17:18+00:00

To avoid unnecessarily increasing the size of struct landlock_layer, we make the layer level a u8 and use the space to store the flags struct. struct layer_access_masks is renamed to struct layer_masks, and a new field is added to track whether a quiet flag rule is seen for each layer. Through use of bitfields, this does not increase the size of the struct. Cc: Justin Suess Assisted-by: GitHub-Copilot:claude-opus-4.8 copilot-review Signed-off-by: Tingmao Wang Co-developed-by: Justin Suess Signed-off-by: Justin Suess Tested-by: Justin Suess Link: https://patch.msgid.link/be3fec3927bc9faaacd4ce0e7f0d1ff5474e2210.1781228815.git.m@maowtm.org [mic: Fix comment formatting] Signed-off-by: Mickaël Salaün

landlock: Fix LANDLOCK_SCOPE_SIGNAL bypass on the SIGIO path

2026-06-13T21:14:59+00:00

LANDLOCK_SCOPE_SIGNAL must prevent a sandboxed process from signaling processes outside its Landlock domain. It can be bypassed through the asynchronous SIGIO delivery path. A sandboxed process that owns any file or socket can arm it with fcntl(fd, F_SETOWN, -pgid), fcntl(fd, F_SETSIG, SIGKILL) and O_ASYNC, so that an I/O event makes the kernel deliver the chosen signal to the whole process group. As the head of its process group's task list (the default position right after fork()) that group can also hold the non-sandboxed process that launched it, e.g. a supervisor or a security monitor. The sandbox can thus kill or signal the processes LANDLOCK_SCOPE_SIGNAL is meant to protect from it. The scope is enforced in hook_file_send_sigiotask() against the Landlock domain recorded at F_SETOWN time, not the live domain of the sender. control_current_fowner() decides whether to record that domain and skips recording it when the fowner target is in the caller's thread group, which is safe only for a single-task target (PIDTYPE_PID, PIDTYPE_TGID). For a process group (PIDTYPE_PGID) pid_task() returns only one member; recording is skipped whenever that member shares the caller's thread group, and hook_file_send_sigiotask() then lets the signal fan out to the whole group unchecked. Record the domain for every non single-process target so the scope is enforced against each group member at delivery time. That recording is necessary but not sufficient on its own: the kernel signals a process group through its members' thread-group leaders, and the leader of the registrant's own process can carry a different Landlock domain than the sibling thread that armed the owner. domain_is_scoped() would then deny that leader, even though commit 18eb75f3af40 ("landlock: Always allow signals between threads of the same process") requires same-process delivery to be allowed. hook_task_kill() avoids this by evaluating same_thread_group() live, per recipient; the SIGIO path instead delegates the whole decision to a single registration-time check, which a process-group fan-out cannot honor. So also record the registrant's thread group next to its domain and exempt it at delivery: hook_file_send_sigiotask() allows the signal whenever the recipient belongs to the registrant's own process, restoring the same-process guarantee while keeping out-of-domain group members blocked. The direct kill() path (hook_task_kill) already evaluates the live domain and is unaffected. Fixes: 18eb75f3af40 ("landlock: Always allow signals between threads of the same process") Cc: stable@vger.kernel.org Signed-off-by: Bryam Vargas Reviewed-by: Günther Noack Link: https://patch.msgid.link/56bffc24f3d0d08b45a686a48e99766b0a0821fa.1780614610.git.hexlabsecurity@proton.me [mic: Check pid_type earlier and improve comment, fix commit message, fix comment formatting] Signed-off-by: Mickaël Salaün

fs: add icount_read_once() and stop open-coding ->i_count loads

2026-05-11T21:12:28+00:00

Similarly to inode_state_read_once(), it makes the caller spell out they acknowledge instability of the returned value. Signed-off-by: Mateusz Guzik Link: https://patch.msgid.link/20260421182538.1215894-2-mjguzik@gmail.com Reviewed-by: Jan Kara Signed-off-by: Christian Brauner

landlock: Clarify BUILD_BUG_ON check in scoping logic

2026-04-07T16:51:07+00:00

The BUILD_BUG_ON check in domain_is_scoped() and unmask_scoped_access() should check that the loop that counts down client_layer finishes. We therefore check that the numbers LANDLOCK_MAX_NUM_LAYERS-1 and -1 are both representable by that integer. If they are representable, the numbers in between are representable too, and the loop finishes. Signed-off-by: Günther Noack Link: https://lore.kernel.org/r/20260327164838.38231-6-gnoack3000@gmail.com Signed-off-by: Mickaël Salaün

landlock: Control pathname UNIX domain socket resolution by path

2026-04-07T16:51:06+00:00

* Add a new access right LANDLOCK_ACCESS_FS_RESOLVE_UNIX, which controls the lookup operations for named UNIX domain sockets. The resolution happens during connect() and sendmsg() (depending on socket type). * Change access_mask_t from u16 to u32 (see below) * Hook into the path lookup in unix_find_bsd() in af_unix.c, using a LSM hook. Make policy decisions based on the new access rights * Increment the Landlock ABI version. * Minor test adaptations to keep the tests working. * Document the design rationale for scoped access rights, and cross-reference it from the header documentation. With this access right, access is granted if either of the following conditions is met: * The target socket's filesystem path was allow-listed using a LANDLOCK_RULE_PATH_BENEATH rule, *or*: * The target socket was created in the same Landlock domain in which LANDLOCK_ACCESS_FS_RESOLVE_UNIX was restricted. In case of a denial, connect() and sendmsg() return EACCES, which is the same error as it is returned if the user does not have the write bit in the traditional UNIX file system permissions of that file. The access_mask_t type grows from u16 to u32 to make space for the new access right. This also doubles the size of struct layer_access_masks from 32 byte to 64 byte. To avoid memory layout inconsistencies between architectures (especially m68k), pack and align struct access_masks [2]. Document the (possible future) interaction between scoped flags and other access rights in struct landlock_ruleset_attr, and summarize the rationale, as discussed in code review leading up to [3]. This feature was created with substantial discussion and input from Justin Suess, Tingmao Wang and Mickaël Salaün. Cc: Tingmao Wang Cc: Justin Suess Cc: Kuniyuki Iwashima Suggested-by: Jann Horn Link[1]: https://github.com/landlock-lsm/linux/issues/36 Link[2]: https://lore.kernel.org/all/20260401.Re1Eesu1Yaij@digikod.net/ Link[3]: https://lore.kernel.org/all/20260205.8531e4005118@gnoack.org/ Signed-off-by: Günther Noack Acked-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/20260327164838.38231-5-gnoack3000@gmail.com [mic: Fix kernel-doc formatting, pack and align access_masks] Signed-off-by: Mickaël Salaün

landlock: Use mem_is_zero() in is_layer_masks_allowed()

2026-04-07T16:51:06+00:00

This is equivalent, but expresses the intent a bit clearer. Signed-off-by: Günther Noack Link: https://lore.kernel.org/r/20260327164838.38231-3-gnoack3000@gmail.com Signed-off-by: Mickaël Salaün

landlock: Improve kernel-doc "Return:" section consistency

2026-04-07T16:51:04+00:00

The canonical kernel-doc form is "Return:" (singular, without trailing "s"). Normalize all existing "Returns:" occurrences across the Landlock source tree to the canonical form. Also fix capitalization for consistency. Balance descriptions to describe all possible returned values. Consolidate bullet-point return descriptions into inline text for functions with simple two-value or three-value returns for consistency. Cc: Günther Noack Reviewed-by: Günther Noack Link: https://lore.kernel.org/r/20260304193134.250495-3-mic@digikod.net Signed-off-by: Mickaël Salaün