noon
(Resending due to an error on the first attempt.)
This series allows to match the SELinux AVC trace events to the
corresponding audit events via the audit event timestamp. This
will help with troubleshooting SELinux denials.
Ondrej Mosnacek (2):
audit: introduce a struct to represent an audit timestamp
selinux: provide matching audit timestamp in the AVC trace event
include/linux/audit.h | 13 +++++++++++++
include/trace/events/avc.h | 25 +++++++++++++++++--------
kernel/audit.c | 23 +++++++++++++++--------
kernel/audit.h | 4 ++--
kernel/auditsc.c | 9 ++++-----
security/selinux/avc.c | 4 +++-
6 files changed, 54 insertions(+), 24 deletions(-)
--
2.38.1
noon
New subject: [PATCH RESEND 1/2] audit: introduce a struct to represent an audit timestamp
Join the two fields that comprise an audit timestamp into a common
structure. This will be used further in later commits.
Signed-off-by: Ondrej Mosnacek <omosnace(a)redhat.com>
---
include/linux/audit.h | 5 +++++
kernel/audit.c | 16 ++++++++--------
kernel/audit.h | 4 ++--
kernel/auditsc.c | 9 ++++-----
4 files changed, 19 insertions(+), 15 deletions(-)
diff --git a/include/linux/audit.h b/include/linux/audit.h
index 3608992848d3..788ab93c3be4 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -84,6 +84,11 @@ enum audit_ntp_type {
AUDIT_NTP_NVALS /* count */
};
+struct audit_timestamp {
+ struct timespec64 t;
+ unsigned int serial;
+};
+
#ifdef CONFIG_AUDITSYSCALL
struct audit_ntp_val {
long long oldval, newval;
diff --git a/kernel/audit.c b/kernel/audit.c
index 9bc0b0301198..aded2d69ea69 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1818,11 +1818,11 @@ unsigned int audit_serial(void)
}
static inline void audit_get_stamp(struct audit_context *ctx,
- struct timespec64 *t, unsigned int *serial)
+ struct audit_timestamp *ts)
{
- if (!ctx || !auditsc_get_stamp(ctx, t, serial)) {
- ktime_get_coarse_real_ts64(t);
- *serial = audit_serial();
+ if (!ctx || !auditsc_get_stamp(ctx, ts)) {
+ ktime_get_coarse_real_ts64(&ts->t);
+ ts->serial = audit_serial();
}
}
@@ -1845,8 +1845,7 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx,
gfp_t gfp_mask,
int type)
{
struct audit_buffer *ab;
- struct timespec64 t;
- unsigned int serial;
+ struct audit_timestamp ts;
if (audit_initialized != AUDIT_INITIALIZED)
return NULL;
@@ -1901,12 +1900,13 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx,
gfp_t gfp_mask,
return NULL;
}
- audit_get_stamp(ab->ctx, &t, &serial);
+ audit_get_stamp(ab->ctx, &ts);
/* cancel dummy context to enable supporting records */
if (ctx)
ctx->dummy = 0;
audit_log_format(ab, "audit(%llu.%03lu:%u): ",
- (unsigned long long)t.tv_sec, t.tv_nsec/1000000, serial);
+ (unsigned long long)ts.t.tv_sec, ts.t.tv_nsec/1000000,
+ ts.serial);
return ab;
}
diff --git a/kernel/audit.h b/kernel/audit.h
index c57b008b9914..e3ea00ea399a 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -262,7 +262,7 @@ extern void audit_put_tty(struct tty_struct *tty);
#ifdef CONFIG_AUDITSYSCALL
extern unsigned int audit_serial(void);
extern int auditsc_get_stamp(struct audit_context *ctx,
- struct timespec64 *t, unsigned int *serial);
+ struct audit_timestamp *ts);
extern void audit_put_watch(struct audit_watch *watch);
extern void audit_get_watch(struct audit_watch *watch);
@@ -303,7 +303,7 @@ extern void audit_filter_inodes(struct task_struct *tsk,
struct audit_context *ctx);
extern struct list_head *audit_killed_trees(void);
#else /* CONFIG_AUDITSYSCALL */
-#define auditsc_get_stamp(c, t, s) 0
+#define auditsc_get_stamp(c, ts) 0
#define audit_put_watch(w) do { } while (0)
#define audit_get_watch(w) do { } while (0)
#define audit_to_watch(k, p, l, o) (-EINVAL)
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 9f8c05228d6d..061009ba9959 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -2513,16 +2513,15 @@ EXPORT_SYMBOL_GPL(__audit_inode_child);
*
* Also sets the context as auditable.
*/
-int auditsc_get_stamp(struct audit_context *ctx,
- struct timespec64 *t, unsigned int *serial)
+int auditsc_get_stamp(struct audit_context *ctx, struct audit_timestamp *ts)
{
if (ctx->context == AUDIT_CTX_UNUSED)
return 0;
if (!ctx->serial)
ctx->serial = audit_serial();
- t->tv_sec = ctx->ctime.tv_sec;
- t->tv_nsec = ctx->ctime.tv_nsec;
- *serial = ctx->serial;
+ ts->t.tv_sec = ctx->ctime.tv_sec;
+ ts->t.tv_nsec = ctx->ctime.tv_nsec;
+ ts->serial = ctx->serial;
if (!ctx->prio) {
ctx->prio = 1;
ctx->current_state = AUDIT_STATE_RECORD;
--
2.38.1
noon
New subject: [PATCH RESEND 2/2] selinux: provide matching audit timestamp in the AVC trace event
In order to make it possible for the users and tooling to associate an
SELinux AVC trace event with the corresponding audit event, make it
include the audit timestamp (including the "serial number") of the
event.
First make audit_log_start() include the timestamp in the audit_buffer
struct and add a public helper to retrieve it from an audit_buffer
instance. Then retrieve it in SELinux's avc_audit_post_callback() and
include it in the "avc:selinux_audited" trace event.
After this patch the even includes the numeric fields that make up the
timestamp and the text representation includes the timestamp in the same
format as used in the audit log - e.g. "audit_ts=1671454430.092:1671".
Signed-off-by: Ondrej Mosnacek <omosnace(a)redhat.com>
---
include/linux/audit.h | 8 ++++++++
include/trace/events/avc.h | 25 +++++++++++++++++--------
kernel/audit.c | 15 +++++++++++----
security/selinux/avc.c | 4 +++-
4 files changed, 39 insertions(+), 13 deletions(-)
diff --git a/include/linux/audit.h b/include/linux/audit.h
index 788ab93c3be4..d6d7acc1b623 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -162,6 +162,9 @@ extern __printf(4, 5)
void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
const char *fmt, ...);
+extern void audit_buffer_get_timestamp(struct audit_buffer *ab,
+ struct audit_timestamp *ts);
+
extern struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
int type);
extern __printf(2, 3)
void audit_log_format(struct audit_buffer *ab, const char *fmt, ...);
@@ -218,6 +221,11 @@ static inline __printf(4, 5)
void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
const char *fmt, ...)
{ }
+static inline void audit_buffer_get_timestamp(struct audit_buffer *ab,
+ struct audit_timestamp *ts)
+{
+ *ts = (struct audit_timestamp){};
+}
static inline struct audit_buffer *audit_log_start(struct audit_context *ctx,
gfp_t gfp_mask, int type)
{
diff --git a/include/trace/events/avc.h b/include/trace/events/avc.h
index b55fda2e0773..8cac14ae22ae 100644
--- a/include/trace/events/avc.h
+++ b/include/trace/events/avc.h
@@ -16,34 +16,43 @@ TRACE_EVENT(selinux_audited,
TP_PROTO(struct selinux_audit_data *sad,
char *scontext,
char *tcontext,
- const char *tclass
+ const char *tclass,
+ const struct audit_timestamp *ts
),
- TP_ARGS(sad, scontext, tcontext, tclass),
+ TP_ARGS(sad, scontext, tcontext, tclass, ts),
TP_STRUCT__entry(
__field(u32, requested)
__field(u32, denied)
__field(u32, audited)
__field(int, result)
+ __field(u64, audit_stamp_sec)
+ __field(u32, audit_stamp_msec)
+ __field(u32, audit_stamp_serial)
__string(scontext, scontext)
__string(tcontext, tcontext)
__string(tclass, tclass)
),
TP_fast_assign(
- __entry->requested = sad->requested;
- __entry->denied = sad->denied;
- __entry->audited = sad->audited;
- __entry->result = sad->result;
+ __entry->requested = sad->requested;
+ __entry->denied = sad->denied;
+ __entry->audited = sad->audited;
+ __entry->result = sad->result;
+ __entry->audit_stamp_sec = ts->t.tv_sec;
+ __entry->audit_stamp_msec = ts->t.tv_nsec / 1000000;
+ __entry->audit_stamp_serial = ts->serial;
__assign_str(tcontext, tcontext);
__assign_str(scontext, scontext);
__assign_str(tclass, tclass);
),
- TP_printk("requested=0x%x denied=0x%x audited=0x%x result=%d scontext=%s
tcontext=%s tclass=%s",
+ TP_printk("requested=0x%x denied=0x%x audited=0x%x result=%d scontext=%s
tcontext=%s tclass=%s audit_ts=%llu.%03u:%u",
__entry->requested, __entry->denied, __entry->audited, __entry->result,
- __get_str(scontext), __get_str(tcontext), __get_str(tclass)
+ __get_str(scontext), __get_str(tcontext), __get_str(tclass),
+ __entry->audit_stamp_sec, __entry->audit_stamp_msec,
+ __entry->audit_stamp_serial
)
);
diff --git a/kernel/audit.c b/kernel/audit.c
index aded2d69ea69..ad21d148704a 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -199,6 +199,7 @@ static struct audit_ctl_mutex {
struct audit_buffer {
struct sk_buff *skb; /* formatted skb ready to send */
struct audit_context *ctx; /* NULL or associated context */
+ struct audit_timestamp ts; /* the timestamp of this record */
gfp_t gfp_mask;
};
@@ -1826,6 +1827,12 @@ static inline void audit_get_stamp(struct audit_context *ctx,
}
}
+void audit_buffer_get_timestamp(struct audit_buffer *ab,
+ struct audit_timestamp *ts)
+{
+ *ts = ab->ts;
+}
+
/**
* audit_log_start - obtain an audit buffer
* @ctx: audit_context (may be NULL)
@@ -1845,7 +1852,6 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx,
gfp_t gfp_mask,
int type)
{
struct audit_buffer *ab;
- struct audit_timestamp ts;
if (audit_initialized != AUDIT_INITIALIZED)
return NULL;
@@ -1900,13 +1906,14 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx,
gfp_t gfp_mask,
return NULL;
}
- audit_get_stamp(ab->ctx, &ts);
+ audit_get_stamp(ab->ctx, &ab->ts);
/* cancel dummy context to enable supporting records */
if (ctx)
ctx->dummy = 0;
audit_log_format(ab, "audit(%llu.%03lu:%u): ",
- (unsigned long long)ts.t.tv_sec, ts.t.tv_nsec/1000000,
- ts.serial);
+ (unsigned long long)ab->ts.t.tv_sec,
+ ab->ts.t.tv_nsec/1000000,
+ ab->ts.serial);
return ab;
}
diff --git a/security/selinux/avc.c b/security/selinux/avc.c
index 9a43af0ebd7d..e59c91eb3228 100644
--- a/security/selinux/avc.c
+++ b/security/selinux/avc.c
@@ -708,6 +708,7 @@ static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
{
struct common_audit_data *ad = a;
struct selinux_audit_data *sad = ad->selinux_audit_data;
+ struct audit_timestamp ts;
char *scontext = NULL;
char *tcontext = NULL;
const char *tclass = NULL;
@@ -735,7 +736,8 @@ static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
if (sad->denied)
audit_log_format(ab, " permissive=%u", sad->result ? 0 : 1);
- trace_selinux_audited(sad, scontext, tcontext, tclass);
+ audit_buffer_get_timestamp(ab, &ts);
+ trace_selinux_audited(sad, scontext, tcontext, tclass, &ts);
kfree(tcontext);
kfree(scontext);
--
2.38.1
4:20 p.m.
New subject: [PATCH RESEND 2/2] selinux: provide matching audit timestamp in the AVC trace event
On Mon, Dec 19, 2022 at 1:00 PM Ondrej Mosnacek <omosnace(a)redhat.com> wrote:
In order to make it possible for the users and tooling to associate an
SELinux AVC trace event with the corresponding audit event, make it
include the audit timestamp (including the "serial number") of the
event.
First make audit_log_start() include the timestamp in the audit_buffer
struct and add a public helper to retrieve it from an audit_buffer
instance. Then retrieve it in SELinux's avc_audit_post_callback() and
include it in the "avc:selinux_audited" trace event.
After this patch the even includes the numeric fields that make up the
timestamp and the text representation includes the timestamp in the same
format as used in the audit log - e.g. "audit_ts=1671454430.092:1671".
Signed-off-by: Ondrej Mosnacek <omosnace(a)redhat.com>
---
include/linux/audit.h | 8 ++++++++
include/trace/events/avc.h | 25 +++++++++++++++++--------
kernel/audit.c | 15 +++++++++++----
security/selinux/avc.c | 4 +++-
4 files changed, 39 insertions(+), 13 deletions(-)
I'm not really liking the idea of exposing the audit timestamp for use
in other subsystems, even if it is just for use in a trace event. I
generally take the approach that audit's charter is to capture and log
security relevant events to userspace where admins and security
officers can use the events to help meet their security goals. While
audit may have some value to developers as a debugging tool, that is
not its primary purpose, and at this point in time I'm not supportive
of adding additional burdens to the audit subsystem to support a
debugging use case (I view exporting and maintaining a proper
timestamp value/struct an additional requirement on the audit
subsystem).
--
paul-moore.com
681
days inactive
681
days old
linux-audit@lists.linux-audit.osci.io
3 comments
2 participants
participants (2)
-
Ondrej Mosnacek -
Paul Moore