Re: [PATCH ghak10 v7 1/2] timekeeping: Audit clock adjustments

Emit an audit record whenever the system clock is changed (i.e. shifted by a non-zero offset) by a syscall from userspace. The syscalls than can (at the time of writing) trigger such record are: - settimeofday(2), stime(2), clock_settime(2) -- via do_settimeofday64() - adjtimex(2), clock_adjtime(2) -- via do_adjtimex() The new records have type AUDIT_TIME_INJOFFSET and contain the following fields: - sec -- the 'seconds' part of the offset - nsec -- the 'nanoseconds' part of the offset Example record (time was shifted backwards by ~16.125 seconds): type=TIME_INJOFFSET msg=audit(1530616049.652:13): sec=-16 nsec=124887145

The records of this type will be associated with the corresponding syscall records. Signed-off-by: Ondrej Mosnacek <omosnace(a)redhat.com&gt;

--- include/linux/audit.h | 14 ++++++++++++++ include/uapi/linux/audit.h | 1 + kernel/auditsc.c | 6 ++++++ kernel/time/timekeeping.c | 6 ++++++ 4 files changed, 27 insertions(+) diff --git a/include/linux/audit.h b/include/linux/audit.h index 1e69d9fe16da..2c62c0468888 100644 --- a/include/linux/audit.h +++ b/include/linux/audit.h @@ -365,6 +365,7 @@ extern void __audit_log_capset(const struct cred *new, const struct cred *old); extern void __audit_mmap_fd(int fd, int flags); extern void __audit_log_kern_module(char *name); extern void __audit_fanotify(unsigned int response); +extern void __audit_tk_injoffset(struct timespec64 offset); static inline void audit_ipc_obj(struct kern_ipc_perm *ipcp) { @@ -467,6 +468,16 @@ static inline void audit_fanotify(unsigned int response) __audit_fanotify(response); } +static inline void audit_tk_injoffset(struct timespec64 offset) +{ + /* ignore no-op events */ + if (offset.tv_sec == 0 && offset.tv_nsec == 0) + return; + + if (!audit_dummy_context()) + __audit_tk_injoffset(offset); +} + extern int audit_n_rules; extern int audit_signals; #else /* CONFIG_AUDITSYSCALL */ @@ -580,6 +591,9 @@ static inline void audit_log_kern_module(char *name) static inline void audit_fanotify(unsigned int response) { } +static inline void audit_tk_injoffset(struct timespec64 offset) +{ } + static inline void audit_ptrace(struct task_struct *t) { } #define audit_n_rules 0 diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h index 3901c51c0b93..ab58d67baf4d 100644 --- a/include/uapi/linux/audit.h +++ b/include/uapi/linux/audit.h @@ -114,6 +114,7 @@ #define AUDIT_REPLACE 1329 /* Replace auditd if this packet unanswerd */ #define AUDIT_KERN_MODULE 1330 /* Kernel Module events */ #define AUDIT_FANOTIFY 1331 /* Fanotify access decision */ +#define AUDIT_TIME_INJOFFSET 1332 /* Timekeeping offset injected */ #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 51a2ceb3a1ca..80dfe0cdc636 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -2512,6 +2512,12 @@ void __audit_fanotify(unsigned int response) AUDIT_FANOTIFY, "resp=%u", response); } +void __audit_tk_injoffset(struct timespec64 offset) +{ + audit_log(audit_context(), GFP_KERNEL, AUDIT_TIME_INJOFFSET, + "sec=%lli nsec=%li", (long long)offset.tv_sec, offset.tv_nsec); +} + static void audit_log_task(struct audit_buffer *ab) { kuid_t auid, uid; diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index f986e1918d12..3d24be4cd607 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -21,6 +21,7 @@ #include <linux/stop_machine.h> #include <linux/pvclock_gtod.h> #include <linux/compiler.h> +#include <linux/audit.h> #include "tick-internal.h" #include "ntp_internal.h" @@ -1250,6 +1251,9 @@ out: /* signal hrtimers about time change */ clock_was_set(); + if (!ret) + audit_tk_injoffset(ts_delta); + return ret; } EXPORT_SYMBOL(do_settimeofday64); @@ -2322,6 +2326,8 @@ int do_adjtimex(struct __kernel_timex *txc) ret = timekeeping_inject_offset(&delta); if (ret) return ret; + + audit_tk_injoffset(delta); } ktime_get_real_ts64(&ts); -- 2.20.1