On 2019-06-11 10:07, Ondrej Mosnacek wrote:
> These strings may come from untrusted sources (e.g. file xattrs) so they
> need to be properly escaped.
>
> Reproducer:
> # setenforce 0
> # touch /tmp/test
> # setfattr -n security.selinux -v 'kuřecí řízek' /tmp/test
> # runcon system_u:system_r:sshd_t:s0 cat /tmp/test
> (look at the generated AVCs)
>
> Actual result:
> type=AVC [...] trawcon=kuřecí řízek
>
> Expected result:
> type=AVC [...] trawcon=6B75C5996563C3AD20C599C3AD7A656B
>
> Fixes: fede148324c3 ("selinux: log invalid contexts in AVCs")
> Cc: stable@xxxxxxxxxxxxxxx # v5.1+
> Signed-off-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx>
Acked-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
> ---
> security/selinux/avc.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/security/selinux/avc.c b/security/selinux/avc.c
> index 8346a4f7c5d7..a99be508f93d 100644
> --- a/security/selinux/avc.c
> +++ b/security/selinux/avc.c
> @@ -739,14 +739,20 @@ static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
> rc = security_sid_to_context_inval(sad->state, sad->ssid, &scontext,
> &scontext_len);
> if (!rc && scontext) {
> - audit_log_format(ab, " srawcon=%s", scontext);
> + if (scontext_len && scontext[scontext_len - 1] == '\0')
> + scontext_len--;
> + audit_log_format(ab, " srawcon=");
> + audit_log_n_untrustedstring(ab, scontext, scontext_len);
> kfree(scontext);
> }
>
> rc = security_sid_to_context_inval(sad->state, sad->tsid, &scontext,
> &scontext_len);
> if (!rc && scontext) {
> - audit_log_format(ab, " trawcon=%s", scontext);
> + if (scontext_len && scontext[scontext_len - 1] == '\0')
> + scontext_len--;
> + audit_log_format(ab, " trawcon=");
> + audit_log_n_untrustedstring(ab, scontext, scontext_len);
> kfree(scontext);
> }
> }
> --
> 2.20.1
>
> --
> Linux-audit mailing list
> Linux-audit@xxxxxxxxxx
> https://www.redhat.com/mailman/listinfo/linux-audit
- RGB
--
Richard Guy Briggs <rgb@xxxxxxxxxx>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635
