[PATCH ghau51/ghau40 v3 6/6] libaudit: add support to get the task audit container identifier

[Richard Guy Briggs <rgb@redhat.com>]

Add the audit_get_containerid() call analogous to audit_getloginuid()
and audit_get_session() calls to get our own audit container identifier.

This is intended as a debug patch, not to be upstreamed.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
---
 docs/Makefile.am             |  2 +-
 docs/audit_get_containerid.3 | 25 +++++++++++++++++++++++++
 lib/libaudit.c               | 29 +++++++++++++++++++++++++++++
 lib/libaudit.h               |  1 +
 4 files changed, 56 insertions(+), 1 deletion(-)
 create mode 100644 docs/audit_get_containerid.3

diff --git a/docs/Makefile.am b/docs/Makefile.am
index cbedc26..a094c56 100644
--- a/docs/Makefile.am
+++ b/docs/Makefile.am
@@ -27,7 +27,7 @@ EXTRA_DIST = $(man_MANS)
 man_MANS = audit_add_rule_data.3 audit_add_watch.3 auditctl.8 auditd.8 \
 auditd.conf.5 audit_delete_rule_data.3 audit_detect_machine.3 \
 audit_encode_nv_string.3 audit_getloginuid.3 \
-audit_get_reply.3 audit_get_session.3 \
+audit_get_reply.3 audit_get_session.3 audit_get_containerid.3 \
 audit_log_acct_message.3 audit_log_user_avc_message.3 \
 audit_log_user_command.3 audit_log_user_comm_message.3 \
 audit_log_user_message.3 audit_log_semanage_message.3 \
diff --git a/docs/audit_get_containerid.3 b/docs/audit_get_containerid.3
new file mode 100644
index 0000000..7d11b9f
--- /dev/null
+++ b/docs/audit_get_containerid.3
@@ -0,0 +1,25 @@
+.TH "AUDIT_GET_CONTAINERID" "3" "Feb 2018" "Red Hat" "Linux Audit API"
+.SH NAME
+audit_get_containerid \- Get a program's container id value
+.SH SYNOPSIS
+.B #include <libaudit.h>
+.sp
+uin32_t audit_get_containerid(void);
+
+.SH DESCRIPTION
+This function returns the task's audit container identifier attribute.
+
+.SH "RETURN VALUE"
+
+This function returns the audit container identifier value if it was set. It will return a \-1 if the audit container identifier is unset. However, since uint64_t is an unsigned type, you will see the converted value instead of \-1.
+
+.SH "ERRORS"
+
+This function returns \-2 on failure. Additionally, in the event of a real error, errno would be set. The function can set errno based on failures of open, read, or strtoul.
+
+.SH "SEE ALSO"
+
+.BR audit_getloginuid (3).
+
+.SH AUTHOR
+Steve Grubb
diff --git a/lib/libaudit.c b/lib/libaudit.c
index 69fb426..ecc2cf4 100644
--- a/lib/libaudit.c
+++ b/lib/libaudit.c
@@ -930,6 +930,35 @@ uint32_t audit_get_session(void)
 		return ses;
 }
 
+/*
+ * This function will retrieve the audit container identifier or -2 if
+ * there is an error.
+ */
+uint64_t audit_get_containerid(void)
+{
+	uint64_t containerid;
+	int len, in;
+	char buf[32];
+
+	errno = 0;
+	in = open("/proc/self/audit_containerid", O_NOFOLLOW|O_RDONLY);
+	if (in < 0)
+		return -2;
+	do {
+		len = read(in, buf, sizeof(buf));
+	} while (len < 0 && errno == EINTR);
+	close(in);
+	if (len < 0 || len >= sizeof(buf))
+		return -2;
+	buf[len] = 0;
+	errno = 0;
+	containerid = strtoull(buf, 0, 10);
+	if (errno)
+		return -2;
+	else
+		return containerid;
+}
+
 int audit_rule_syscall_data(struct audit_rule_data *rule, int scall)
 {
 	int word = AUDIT_WORD(scall);
diff --git a/lib/libaudit.h b/lib/libaudit.h
index 6d6f99e..a97d0d2 100644
--- a/lib/libaudit.h
+++ b/lib/libaudit.h
@@ -564,6 +564,7 @@ extern int  audit_get_reply(int fd, struct audit_reply *rep, reply_t block,
 extern uid_t audit_getloginuid(void);
 extern int  audit_setloginuid(uid_t uid);
 extern uint32_t audit_get_session(void);
+extern uint64_t audit_get_containerid(void);
 extern int  audit_detect_machine(void);
 extern int audit_determine_machine(const char *arch);
 
-- 
1.8.3.1