This renames the very specific audit_log_link_denied() to audit_log_path_denied() and adds the AUDIT_* type as an argument. This allows for the creation of the new AUDIT_ANOM_CREAT that can be used to report the fifo/regular file creation restrictions that were introduced in commit 30aba6656f61 ("namei: allow restricted O_CREAT of FIFOs and regular files"). Without this change, discovering that the restriction is enabled can be very challenging: https://lore.kernel.org/lkml/CA+jJMxvkqjXHy3DnV5MVhFTL2RUhg0WQ-XVFW3ngDQO... Reported-by: Jérémie Galarneau <jeremie.galarneau(a)efficios.com&gt; Signed-off-by: Kees Cook <keescook(a)chromium.org&gt; --- This is not a complete fix because reporting was broken in commit 15564ff0a16e ("audit: make ANOM_LINK obey audit_enabled and audit_dummy_context") which specifically goes against the intention of these records: they should _always_ be reported. If auditing isn't enabled, they should be ratelimited. Instead of using audit, should this just go back to using pr_ratelimited()? --- fs/namei.c | 7 +++++-- include/linux/audit.h | 5 +++-- include/uapi/linux/audit.h | 1 + kernel/audit.c | 11 ++++++----- 4 files changed, 15 insertions(+), 9 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index 671c3c1a3425..0e60f81e1d5a 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -925,7 +925,7 @@ static inline int may_follow_link(struct nameidata *nd) return -ECHILD; audit_inode(nd->name, nd->stack[0].link.dentry, 0); - audit_log_link_denied("follow_link"); + audit_log_path_denied(AUDIT_ANOM_LINK, "follow_link"); return -EACCES; } @@ -993,7 +993,7 @@ static int may_linkat(struct path *link) if (safe_hardlink_source(inode) || inode_owner_or_capable(inode)) return 0; - audit_log_link_denied("linkat"); + audit_log_path_denied(AUDIT_ANOM_LINK, "linkat"); return -EPERM; } @@ -1031,6 +1031,9 @@ static int may_create_in_sticky(struct dentry * const dir, (dir->d_inode->i_mode & 0020 && ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) || (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) { + audit_log_path_denied(AUDIT_ANOM_CREAT, + S_ISFIFO(inode->i_mode) ? "fifo" + : "regular"); return -EACCES; } return 0; diff --git a/include/linux/audit.h b/include/linux/audit.h index aee3dc9eb378..b3715e2ee1c5 100644 --- a/include/linux/audit.h +++ b/include/linux/audit.h @@ -156,7 +156,8 @@ extern void audit_log_d_path(struct audit_buffer *ab, const struct path *path); extern void audit_log_key(struct audit_buffer *ab, char *key); -extern void audit_log_link_denied(const char *operation); +extern void audit_log_path_denied(int type, + const char *operation); extern void audit_log_lost(const char *message); extern int audit_log_task_context(struct audit_buffer *ab); @@ -217,7 +218,7 @@ static inline void audit_log_d_path(struct audit_buffer *ab, { } static inline void audit_log_key(struct audit_buffer *ab, char *key) { } -static inline void audit_log_link_denied(const char *string) +static inline void audit_log_path_denied(int type, const char *string); { } static inline int audit_log_task_context(struct audit_buffer *ab) { diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h index c89c6495983d..3ad935527177 100644 --- a/include/uapi/linux/audit.h +++ b/include/uapi/linux/audit.h @@ -143,6 +143,7 @@ #define AUDIT_ANOM_PROMISCUOUS 1700 /* Device changed promiscuous mode */ #define AUDIT_ANOM_ABEND 1701 /* Process ended abnormally */ #define AUDIT_ANOM_LINK 1702 /* Suspicious use of file links */ +#define AUDIT_ANOM_CREAT 1703 /* Suspicious file creation */ #define AUDIT_INTEGRITY_DATA 1800 /* Data integrity verification */ #define AUDIT_INTEGRITY_METADATA 1801 /* Metadata integrity verification */ #define AUDIT_INTEGRITY_STATUS 1802 /* Integrity enable status */ diff --git a/kernel/audit.c b/kernel/audit.c index da8dc0db5bd3..ed7402ac81b6 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -2155,18 +2155,19 @@ void audit_log_task_info(struct audit_buffer *ab) EXPORT_SYMBOL(audit_log_task_info); /** - * audit_log_link_denied - report a link restriction denial - * @operation: specific link operation + * audit_log_path_denied - report a path restriction denial + * @type: audit message type (AUDIT_ANOM_LINK, AUDIT_ANOM_CREAT, etc) + * @operation: specific operation name */ -void audit_log_link_denied(const char *operation) +void audit_log_path_denied(int type, const char *operation) { struct audit_buffer *ab; if (!audit_enabled || audit_dummy_context()) return; - /* Generate AUDIT_ANOM_LINK with subject, operation, outcome. */ - ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_ANOM_LINK); + /* Generate log with subject, operation, outcome. */ + ab = audit_log_start(audit_context(), GFP_KERNEL, type); if (!ab) return; audit_log_format(ab, "op=%s", operation); -- 2.17.1 -- Kees Cook