[PATCH v2] audit: create explicit AUDIT_SECCOMP event type

[PATCH v2] audit: create explicit AUDIT_SECCOMP event type

[Kees Cook]

The seccomp path was using AUDIT_ANOM_ABEND from when seccomp mode 1
could only kill a process. While we still want to make sure an audit
record is forced on a kill, this should use a separate record type since
seccomp mode 2 introduces other behaviors. In the case of "handled"
behaviors (process wasn't killed), only emit a record if the process is
under inspection. This change also fixes userspace examination of seccomp
audit events, since it was considered malformed due to missing fields of
the AUDIT_ANOM_ABEND event type.

Cc: Julien Tinnes <jln@google.com>
Cc: Will Drewry <wad@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Steve Grubb <sgrubb@redhat.com>
---
v2:
 - update commit message and add Cc to stable, suggested by Steve Grubb

---
 include/linux/audit.h      |    3 ++-
 include/uapi/linux/audit.h |    1 +
 kernel/auditsc.c           |   14 +++++++++++---
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/include/linux/audit.h b/include/linux/audit.h
index bce729a..9d5104d 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -157,7 +157,8 @@ void audit_core_dumps(long signr);
 
 static inline void audit_seccomp(unsigned long syscall, long signr, int code)
 {
-	if (unlikely(!audit_dummy_context()))
+	/* Force a record to be reported if a signal was delivered. */
+	if (signr || unlikely(!audit_dummy_context()))
 		__audit_seccomp(syscall, signr, code);
 }
 
diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
index 76352ac..09a2d94 100644
--- a/include/uapi/linux/audit.h
+++ b/include/uapi/linux/audit.h
@@ -106,6 +106,7 @@
 #define AUDIT_MMAP		1323	/* Record showing descriptor and flags in mmap */
 #define AUDIT_NETFILTER_PKT	1324	/* Packets traversing netfilter chains */
 #define AUDIT_NETFILTER_CFG	1325	/* Netfilter chain modifications */
+#define AUDIT_SECCOMP		1326	/* Secure Computing event */
 
 #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 2f186ed..157e989 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -2735,7 +2735,7 @@ void __audit_mmap_fd(int fd, int flags)
 	context->type = AUDIT_MMAP;
 }
 
-static void audit_log_abend(struct audit_buffer *ab, char *reason, long signr)
+static void audit_log_task(struct audit_buffer *ab)
 {
 	kuid_t auid, uid;
 	kgid_t gid;
@@ -2753,6 +2753,11 @@ static void audit_log_abend(struct audit_buffer *ab, char *reason, long signr)
 	audit_log_task_context(ab);
 	audit_log_format(ab, " pid=%d comm=", current->pid);
 	audit_log_untrustedstring(ab, current->comm);
+}
+
+static void audit_log_abend(struct audit_buffer *ab, char *reason, long signr)
+{
+	audit_log_task(ab);
 	audit_log_format(ab, " reason=");
 	audit_log_string(ab, reason);
 	audit_log_format(ab, " sig=%ld", signr);
@@ -2783,8 +2788,11 @@ void __audit_seccomp(unsigned long syscall, long signr, int code)
 {
 	struct audit_buffer *ab;
 
-	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_ANOM_ABEND);
-	audit_log_abend(ab, "seccomp", signr);
+	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_SECCOMP);
+	if (unlikely(!ab))
+		return;
+	audit_log_task(ab);
+	audit_log_format(ab, " sig=%ld", signr);
 	audit_log_format(ab, " syscall=%ld", syscall);
 	audit_log_format(ab, " compat=%d", is_compat_task());
 	audit_log_format(ab, " ip=0x%lx", KSTK_EIP(current));
-- 
1.7.9.5


-- 
Kees Cook
Chrome OS Security

Re: [PATCH v2] audit: create explicit AUDIT_SECCOMP event type

[Will Drewry]

Thanks!

Acked-by: Will Drewry <wad@chromium.org>

On Wed, Nov 28, 2012 at 5:15 PM, Kees Cook <keescook@chromium.org> wrote:
> The seccomp path was using AUDIT_ANOM_ABEND from when seccomp mode 1
> could only kill a process. While we still want to make sure an audit
> record is forced on a kill, this should use a separate record type since
> seccomp mode 2 introduces other behaviors. In the case of "handled"
> behaviors (process wasn't killed), only emit a record if the process is
> under inspection. This change also fixes userspace examination of seccomp
> audit events, since it was considered malformed due to missing fields of
> the AUDIT_ANOM_ABEND event type.
>
> Cc: Julien Tinnes <jln@google.com>
> Cc: Will Drewry <wad@google.com>
> Cc: stable@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> Acked-by: Steve Grubb <sgrubb@redhat.com>
> ---
> v2:
>  - update commit message and add Cc to stable, suggested by Steve Grubb
>
> ---
>  include/linux/audit.h      |    3 ++-
>  include/uapi/linux/audit.h |    1 +
>  kernel/auditsc.c           |   14 +++++++++++---
>  3 files changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/audit.h b/include/linux/audit.h
> index bce729a..9d5104d 100644
> --- a/include/linux/audit.h
> +++ b/include/linux/audit.h
> @@ -157,7 +157,8 @@ void audit_core_dumps(long signr);
>
>  static inline void audit_seccomp(unsigned long syscall, long signr, int code)
>  {
> -       if (unlikely(!audit_dummy_context()))
> +       /* Force a record to be reported if a signal was delivered. */
> +       if (signr || unlikely(!audit_dummy_context()))
>                 __audit_seccomp(syscall, signr, code);
>  }
>
> diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
> index 76352ac..09a2d94 100644
> --- a/include/uapi/linux/audit.h
> +++ b/include/uapi/linux/audit.h
> @@ -106,6 +106,7 @@
>  #define AUDIT_MMAP             1323    /* Record showing descriptor and flags in mmap */
>  #define AUDIT_NETFILTER_PKT    1324    /* Packets traversing netfilter chains */
>  #define AUDIT_NETFILTER_CFG    1325    /* Netfilter chain modifications */
> +#define AUDIT_SECCOMP          1326    /* Secure Computing event */
>
>  #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 2f186ed..157e989 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -2735,7 +2735,7 @@ void __audit_mmap_fd(int fd, int flags)
>         context->type = AUDIT_MMAP;
>  }
>
> -static void audit_log_abend(struct audit_buffer *ab, char *reason, long signr)
> +static void audit_log_task(struct audit_buffer *ab)
>  {
>         kuid_t auid, uid;
>         kgid_t gid;
> @@ -2753,6 +2753,11 @@ static void audit_log_abend(struct audit_buffer *ab, char *reason, long signr)
>         audit_log_task_context(ab);
>         audit_log_format(ab, " pid=%d comm=", current->pid);
>         audit_log_untrustedstring(ab, current->comm);
> +}
> +
> +static void audit_log_abend(struct audit_buffer *ab, char *reason, long signr)
> +{
> +       audit_log_task(ab);
>         audit_log_format(ab, " reason=");
>         audit_log_string(ab, reason);
>         audit_log_format(ab, " sig=%ld", signr);
> @@ -2783,8 +2788,11 @@ void __audit_seccomp(unsigned long syscall, long signr, int code)
>  {
>         struct audit_buffer *ab;
>
> -       ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_ANOM_ABEND);
> -       audit_log_abend(ab, "seccomp", signr);
> +       ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_SECCOMP);
> +       if (unlikely(!ab))
> +               return;
> +       audit_log_task(ab);
> +       audit_log_format(ab, " sig=%ld", signr);
>         audit_log_format(ab, " syscall=%ld", syscall);
>         audit_log_format(ab, " compat=%d", is_compat_task());
>         audit_log_format(ab, " ip=0x%lx", KSTK_EIP(current));
> --
> 1.7.9.5
>
>
> --
> Kees Cook
> Chrome OS Security