Modern mount tools (util-linux >= 2.39.1) use the new mount API (fsopen, fsconfig, fsmount, move_mount) instead of the legacy mount(2) syscall. The generic SYSCALL audit record logs the move_mount syscall but does not capture the flags argument, creating an audit gap for mount relocation operations.
Add a MOVE_MOUNT auxiliary record that logs the flags argument passed to move_mount(2). Pathnames and file descriptors are captured through existing PATH records and SYSCALL record arguments. ---- type=PATH : item=0 name=/mnt/test_src inode=1 dev=00:41 ... type=SYSCALL : arch=x86_64 syscall=move_mount ... type=MOVE_MOUNT : fs_flags=0x4 ---- type=PATH : item=0 name=/mnt/test_dst inode=27460862 dev=fc:00 ... type=SYSCALL : arch=x86_64 syscall=move_mount ... type=MOVE_MOUNT : fs_flags=0x4 Link: https://github.com/linux-audit/audit-kernel/issues/152 Link: https://github.com/linux-audit/audit-kernel/issues/153 Signed-off-by: Ricardo Robaina <[email protected]> --- fs/namespace.c | 3 +++ include/linux/audit.h | 10 ++++++++++ include/uapi/linux/audit.h | 1 + kernel/auditsc.c | 13 +++++++++++++ 4 files changed, 27 insertions(+) diff --git a/fs/namespace.c b/fs/namespace.c index 3d5cd5bf3b05..a6b0286744d9 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -34,6 +34,7 @@ #include <linux/mnt_idmapping.h> #include <linux/pidfs.h> #include <linux/nstree.h> +#include <linux/audit.h> #include "pnode.h" #include "internal.h" @@ -4625,6 +4626,8 @@ SYSCALL_DEFINE5(move_mount, if (flags & MOVE_MOUNT_F_EMPTY_PATH) uflags = AT_EMPTY_PATH; + audit_log_move_mount(flags); + CLASS(filename_maybe_null,from_name)(from_pathname, uflags); if (!from_name && from_dfd >= 0) { CLASS(fd_raw, f_from)(from_dfd); diff --git a/include/linux/audit.h b/include/linux/audit.h index 45abb3722d30..d1dc4035cb3c 100644 --- a/include/linux/audit.h +++ b/include/linux/audit.h @@ -449,6 +449,7 @@ extern void __audit_tk_injoffset(struct timespec64 offset); extern void __audit_ntp_log(const struct audit_ntp_data *ad); extern void __audit_log_nfcfg(const char *name, u8 af, unsigned int nentries, enum audit_nfcfgop op, gfp_t gfp); +extern void __audit_log_move_mount(unsigned int flags); static inline void audit_ipc_obj(struct kern_ipc_perm *ipcp) { @@ -598,6 +599,12 @@ static inline void audit_log_nfcfg(const char *name, u8 af, __audit_log_nfcfg(name, af, nentries, op, gfp); } +static inline void audit_log_move_mount(unsigned int flags) +{ + if (!audit_dummy_context()) + __audit_log_move_mount(flags); +} + extern int audit_n_rules; extern int audit_signals; #else /* CONFIG_AUDITSYSCALL */ @@ -730,6 +737,9 @@ static inline void audit_log_nfcfg(const char *name, u8 af, enum audit_nfcfgop op, gfp_t gfp) { } +static inline void audit_log_move_mount(unsigned int flags) +{ } + #define audit_n_rules 0 #define audit_signals 0 #endif /* CONFIG_AUDITSYSCALL */ diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h index e8f5ce677df7..40abf3dfd307 100644 --- a/include/uapi/linux/audit.h +++ b/include/uapi/linux/audit.h @@ -122,6 +122,7 @@ #define AUDIT_OPENAT2 1337 /* Record showing openat2 how args */ #define AUDIT_DM_CTRL 1338 /* Device Mapper target control */ #define AUDIT_DM_EVENT 1339 /* Device Mapper events */ +#define AUDIT_MOVE_MOUNT 1342 /* Record showing move_mount flags */ #define AUDIT_AVC 1400 /* SE Linux avc denial or grant */ #define AUDIT_SELINUX_ERR 1401 /* Internal SE Linux Errors */ diff --git a/kernel/auditsc.c b/kernel/auditsc.c index 6610e667c728..4aca04d33d00 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -2882,6 +2882,19 @@ void __audit_log_nfcfg(const char *name, u8 af, unsigned int nentries, } EXPORT_SYMBOL_GPL(__audit_log_nfcfg); +void __audit_log_move_mount(unsigned int flags) +{ + struct audit_buffer *ab; + + ab = audit_log_start(audit_context(), GFP_KERNEL, + AUDIT_MOVE_MOUNT); + if (!ab) + return; + + audit_log_format(ab, "fs_flags=0x%x", flags); + audit_log_end(ab); +} + static void audit_log_task(struct audit_buffer *ab) { kuid_t auid, uid; -- 2.53.0
