Add audit support for unix_stream_connect, unix_may_send, task_kill, and file_send_sigiotask hooks.
The related blockers are: - scope.abstract_unix_socket - scope.signal Audit event sample for abstract unix socket: type=LANDLOCK_DENY msg=audit(1729738800.268:30): domain=195ba459b blockers=scope.abstract_unix_socket path=00666F6F Audit event sample for signal: type=LANDLOCK_DENY msg=audit(1729738800.291:31): domain=195ba459b blockers=scope.signal opid=1 ocomm="systemd" Refactor and simplify error handling in LSM hooks. Extend struct landlock_file_security with fown_layer and use it to log the blocking domain. The struct aligned size is still 16 bytes. Cc: Günther Noack <[email protected]> Cc: Tahera Fahimi <[email protected]> Signed-off-by: Mickaël Salaün <[email protected]> --- Changes since v6: - Fix missing ifdef CONFIG_AUDIT for fown_layer, spotted by kernel test robot. - Update headers. Changes since v5: - Move request declarations in the landlock_log_denial() calls to not impact allowed requests with audit, and return as soon as possible when access is allowed. - Store a fown_layer per file and use it to log the blocking domain. - Refactor and simplify error handling in LSM hooks. Changes since v4: - Rebase on top of the landlock_log_denial() and subject type changes. Changes since v3: - Cosmetic change to the "scope.*" blocker names. - Extend commit message. Changes since v1: - New patch. --- security/landlock/audit.c | 8 ++++ security/landlock/audit.h | 2 + security/landlock/fs.c | 8 +++- security/landlock/fs.h | 16 ++++++++ security/landlock/task.c | 84 +++++++++++++++++++++++++++++++-------- 5 files changed, 99 insertions(+), 19 deletions(-) diff --git a/security/landlock/audit.c b/security/landlock/audit.c index 66ff9a5d9866..2dcc55ad451c 100644 --- a/security/landlock/audit.c +++ b/security/landlock/audit.c @@ -70,6 +70,14 @@ get_blocker(const enum landlock_request_type type, if (WARN_ON_ONCE(access_bit >= ARRAY_SIZE(net_access_strings))) return "unknown"; return net_access_strings[access_bit]; + + case LANDLOCK_REQUEST_SCOPE_ABSTRACT_UNIX_SOCKET: + WARN_ON_ONCE(access_bit != -1); + return "scope.abstract_unix_socket"; + + case LANDLOCK_REQUEST_SCOPE_SIGNAL: + WARN_ON_ONCE(access_bit != -1); + return "scope.signal"; } WARN_ON_ONCE(1); diff --git a/security/landlock/audit.h b/security/landlock/audit.h index 486b4e7050d3..92428b7fc4d8 100644 --- a/security/landlock/audit.h +++ b/security/landlock/audit.h @@ -19,6 +19,8 @@ enum landlock_request_type { LANDLOCK_REQUEST_FS_CHANGE_TOPOLOGY, LANDLOCK_REQUEST_FS_ACCESS, LANDLOCK_REQUEST_NET_ACCESS, + LANDLOCK_REQUEST_SCOPE_ABSTRACT_UNIX_SOCKET, + LANDLOCK_REQUEST_SCOPE_SIGNAL, }; /* diff --git a/security/landlock/fs.c b/security/landlock/fs.c index 9d7443ff67c7..36d06a8e2287 100644 --- a/security/landlock/fs.c +++ b/security/landlock/fs.c @@ -1774,6 +1774,7 @@ static void hook_file_set_fowner(struct file *file) struct landlock_ruleset *prev_dom; struct task_struct *p; struct landlock_cred_security fown_subject = {}; + size_t fown_layer = 0; /* * Lock already held by __f_setown(), see commit 26f204380a3c ("fs: Fix @@ -1791,8 +1792,8 @@ static void hook_file_set_fowner(struct file *file) .scope = LANDLOCK_SCOPE_SIGNAL, }; const struct landlock_cred_security *new_subject = - landlock_get_applicable_subject(current_cred(), - signal_scope, NULL); + landlock_get_applicable_subject( + current_cred(), signal_scope, &fown_layer); if (new_subject) { landlock_get_ruleset(new_subject->domain); fown_subject = *new_subject; @@ -1801,6 +1802,9 @@ static void hook_file_set_fowner(struct file *file) prev_dom = landlock_file(file)->fown_subject.domain; landlock_file(file)->fown_subject = fown_subject; +#ifdef CONFIG_AUDIT + landlock_file(file)->fown_layer = fown_layer; +#endif /* CONFIG_AUDIT*/ /* Called in an RCU read-side critical section. */ landlock_put_ruleset_deferred(prev_dom); diff --git a/security/landlock/fs.h b/security/landlock/fs.h index 3a09ba985b74..294ca813c7f2 100644 --- a/security/landlock/fs.h +++ b/security/landlock/fs.h @@ -9,6 +9,7 @@ #ifndef _SECURITY_LANDLOCK_FS_H #define _SECURITY_LANDLOCK_FS_H +#include <linux/build_bug.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/rcupdate.h> @@ -61,6 +62,11 @@ struct landlock_file_security { * _LANDLOCK_ACCESS_FS_OPTIONAL). */ deny_masks_t deny_masks; + /** + * @fown_layer: Layer level of @fown_subject->domain with + * LANDLOCK_SCOPE_SIGNAL. + */ + u8 fown_layer; #endif /* CONFIG_AUDIT */ /** @@ -73,6 +79,16 @@ struct landlock_file_security { struct landlock_cred_security fown_subject; }; +#ifdef CONFIG_AUDIT + +/* Makes sure all layers can be identified. */ +/* clang-format off */ +static_assert((typeof_member(struct landlock_file_security, fown_layer))~0 >= + LANDLOCK_MAX_NUM_LAYERS); +/* clang-format off */ + +#endif /* CONFIG_AUDIT */ + /** * struct landlock_superblock_security - Superblock security blob * diff --git a/security/landlock/task.c b/security/landlock/task.c index 60e2953d2c71..e95e4ebe724d 100644 --- a/security/landlock/task.c +++ b/security/landlock/task.c @@ -1,9 +1,10 @@ // SPDX-License-Identifier: GPL-2.0-only /* - * Landlock LSM - Ptrace hooks + * Landlock - Ptrace hooks * * Copyright © 2017-2020 Mickaël Salaün <[email protected]> * Copyright © 2019-2020 ANSSI + * Copyright © 2021-2025 Microsoft Corporation */ #include <asm/current.h> @@ -265,26 +266,41 @@ static int hook_unix_stream_connect(struct sock *const sock, struct sock *const other, struct sock *const newsk) { + size_t handle_layer; const struct landlock_cred_security *const subject = landlock_get_applicable_subject(current_cred(), unix_scope, - NULL); + &handle_layer); /* Quick return for non-landlocked tasks. */ if (!subject) return 0; - if (is_abstract_socket(other) && sock_is_scoped(other, subject->domain)) - return -EPERM; + if (!is_abstract_socket(other)) + return 0; + + if (!sock_is_scoped(other, subject->domain)) + return 0; - return 0; + landlock_log_denial(subject, &(struct landlock_request) { + .type = LANDLOCK_REQUEST_SCOPE_ABSTRACT_UNIX_SOCKET, + .audit = { + .type = LSM_AUDIT_DATA_NET, + .u.net = &(struct lsm_network_audit) { + .sk = other, + }, + }, + .layer_plus_one = handle_layer + 1, + }); + return -EPERM; } static int hook_unix_may_send(struct socket *const sock, struct socket *const other) { + size_t handle_layer; const struct landlock_cred_security *const subject = landlock_get_applicable_subject(current_cred(), unix_scope, - NULL); + &handle_layer); if (!subject) return 0; @@ -296,11 +312,23 @@ static int hook_unix_may_send(struct socket *const sock, if (unix_peer(sock->sk) == other->sk) return 0; - if (is_abstract_socket(other->sk) && - sock_is_scoped(other->sk, subject->domain)) - return -EPERM; + if (!is_abstract_socket(other->sk)) + return 0; + + if (!sock_is_scoped(other->sk, subject->domain)) + return 0; - return 0; + landlock_log_denial(subject, &(struct landlock_request) { + .type = LANDLOCK_REQUEST_SCOPE_ABSTRACT_UNIX_SOCKET, + .audit = { + .type = LSM_AUDIT_DATA_NET, + .u.net = &(struct lsm_network_audit) { + .sk = other->sk, + }, + }, + .layer_plus_one = handle_layer + 1, + }); + return -EPERM; } static const struct access_masks signal_scope = { @@ -312,6 +340,7 @@ static int hook_task_kill(struct task_struct *const p, const struct cred *cred) { bool is_scoped; + size_t handle_layer; const struct landlock_cred_security *subject; if (!cred) { @@ -330,7 +359,8 @@ static int hook_task_kill(struct task_struct *const p, cred = current_cred(); } - subject = landlock_get_applicable_subject(cred, signal_scope, NULL); + subject = landlock_get_applicable_subject(cred, signal_scope, + &handle_layer); /* Quick return for non-landlocked tasks. */ if (!subject) @@ -342,10 +372,19 @@ static int hook_task_kill(struct task_struct *const p, landlock_get_task_domain(p), signal_scope.scope); } - if (is_scoped) - return -EPERM; - return 0; + if (!is_scoped) + return 0; + + landlock_log_denial(subject, &(struct landlock_request) { + .type = LANDLOCK_REQUEST_SCOPE_SIGNAL, + .audit = { + .type = LSM_AUDIT_DATA_TASK, + .u.tsk = p, + }, + .layer_plus_one = handle_layer + 1, + }); + return -EPERM; } static int hook_file_send_sigiotask(struct task_struct *tsk, @@ -374,10 +413,21 @@ static int hook_file_send_sigiotask(struct task_struct *tsk, landlock_get_task_domain(tsk), signal_scope.scope); } - if (is_scoped) - return -EPERM; - return 0; + if (!is_scoped) + return 0; + + landlock_log_denial(subject, &(struct landlock_request) { + .type = LANDLOCK_REQUEST_SCOPE_SIGNAL, + .audit = { + .type = LSM_AUDIT_DATA_TASK, + .u.tsk = tsk, + }, +#ifdef CONFIG_AUDIT + .layer_plus_one = landlock_file(fown->file)->fown_layer + 1, +#endif /* CONFIG_AUDIT */ + }); + return -EPERM; } static struct security_hook_list landlock_hooks[] __ro_after_init = { -- 2.49.0
