[PATCH ghau51/ghau40 v9 08/11] add support for audit_signal_info2

From: Richard Guy Briggs
Date: Sat Jun 27 2020 - 11:19:46 EST

Since a process in a container could potentially signal the audit daemon
(reconfig, terminate, roll log, resume), that audit container identifier
information should be made available to the audit daemon to report the
full provenance of the signal. It is not possible to add it to the
existing audit_signal_info struct without causing a kABI change.
Introduce a new audit message type AUDIT_SIGNAL_INFO2 using a new
audit_sig_info2 struct to be able to transfer this information from
kernel to userspace.

struct audit_sig_info2 {
uid_t uid;
pid_t pid;
uint64_t cid;
char ctx[];
};

Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
---
auparse/auditd-config.c | 1 +
docs/audit_request_signal_info.3 | 15 ++++++++++-
lib/libaudit.c | 56 ++++++++++++++++++++++++++++++++++------
lib/libaudit.h | 16 +++++++++++-
lib/msg_typetab.h | 1 +
lib/netlink.c | 4 +++
src/auditd-config.c | 1 +
src/auditd-config.h | 1 +
src/auditd-event.c | 10 ++++++-
src/auditd-reconfig.c | 25 +++++++++++++-----
src/auditd.c | 4 ++-
11 files changed, 116 insertions(+), 18 deletions(-)

diff --git a/auparse/auditd-config.c b/auparse/auditd-config.c
index 59984b47bd5a..7a3ed33ffb4b 100644
--- a/auparse/auditd-config.c
+++ b/auparse/auditd-config.c
@@ -77,6 +77,7 @@ void clear_config(struct daemon_conf *config)
config->sender_uid = 0;
config->sender_pid = 0;
config->sender_ctx = NULL;
+ config->sender_cid = NULL;
config->write_logs = 1;
config->log_file = strdup("/var/log/audit/audit.log");
config->log_format = LF_RAW;
diff --git a/docs/audit_request_signal_info.3 b/docs/audit_request_signal_info.3
index b68d7bbefeed..90c5da5bcf7d 100644
--- a/docs/audit_request_signal_info.3
+++ b/docs/audit_request_signal_info.3
@@ -14,10 +14,23 @@ audit_request_signal_info requests that the kernel send information about the se
struct audit_sig_info {
uid_t uid;
pid_t pid;
- char ctx[0];
+ char ctx[];
};
.fi

+If the process has an audit container identifier, the signal info structure is as follows:
+
+.nf
+struct audit_sig_info2 {
+ uid_t uid;
+ pid_t pid;
+ uint32_t cid_len;
+ char data[];
+};
+.fi
+
+The data field contains first the audit container identifier list of length cid_len, followed by the SElinux context to the end of the structure.
+
This function is likely to be used only by audit daemons and shouldn't be called by any other kind of program.

.SH "RETURN VALUE"
diff --git a/lib/libaudit.c b/lib/libaudit.c
index e64bc4628da4..1a7fed76b9b0 100644
--- a/lib/libaudit.c
+++ b/lib/libaudit.c
@@ -25,6 +25,7 @@
#include "config.h"
#include <stdio.h>
#include <stdarg.h>
+#include <stdbool.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
@@ -667,7 +668,12 @@ int audit_request_rules_list_data(int fd)

int audit_request_signal_info(int fd)
{
- int rc = audit_send(fd, AUDIT_SIGNAL_INFO, NULL, 0);
+ int rc;
+
+ if (audit_get_containerid() == (uint64_t)-2)
+ rc = audit_send(fd, AUDIT_SIGNAL_INFO, NULL, 0);
+ else
+ rc = audit_send(fd, AUDIT_SIGNAL_INFO2, NULL, 0);
if (rc < 0)
audit_msg(LOG_WARNING,
"Error sending signal_info request (%s)",
@@ -675,16 +681,50 @@ int audit_request_signal_info(int fd)
return rc;
}

+bool audit_signal_info_has_ctx(struct audit_reply *rep)
+{
+ if (rep->type == AUDIT_SIGNAL_INFO) {
+ if (rep->len == 24)
+ return false;
+ } else {
+ if (rep->len == 24 + sizeof(uint32_t) + rep->signal_info2->cid_len)
+ return false;
+ }
+ return true;
+}
+
+#ifndef MIN
+#define MIN(a, b) (((a) <= (b)) ? (a) : (b))
+#endif
char *audit_format_signal_info(char *buf, int len, char *op,
struct audit_reply *rep, char *res)
{
- if (rep->len == 24)
- snprintf(buf, len, "op=%s auid=%u pid=%d res=%s", op,
- rep->signal_info->uid, rep->signal_info->pid, res);
- else
- snprintf(buf, len, "op=%s auid=%u pid=%d subj=%s res=%s",
- op, rep->signal_info->uid, rep->signal_info->pid,
- rep->signal_info->ctx, res);
+ int c = 0;
+
+ if (rep->type == AUDIT_SIGNAL_INFO) {
+ c += snprintf(buf + c, len - c, "op=%s auid=%u pid=%d",
+ op,
+ rep->signal_info->uid,
+ rep->signal_info->pid);
+ if (audit_signal_info_has_ctx(rep))
+ c += snprintf(buf + c, len - c, " subj=%s",
+ rep->signal_info->ctx);
+ c += snprintf(buf + c, len - c, " res=%s", res);
+ } else {
+ c += snprintf(buf + c, len - c, "op=%s auid=%u pid=%d",
+ op,
+ rep->signal_info2->uid,
+ rep->signal_info2->pid);
+ if (audit_signal_info_has_ctx(rep))
+ c += snprintf(buf + c, len - c, " subj=%s",
+ rep->signal_info2->data +
+ rep->signal_info2->cid_len);
+ c += snprintf(buf + c, len - c, " res=%s", res);
+ if (rep->signal_info2->cid_len != 0)
+ c += snprintf(buf + c,
+ MIN(len - c, rep->signal_info2->cid_len),
+ " contid=%s", rep->signal_info2->data);
+ }
return buf;
}

diff --git a/lib/libaudit.h b/lib/libaudit.h
index ec171e4d08f3..f4e820e9b097 100644
--- a/lib/libaudit.h
+++ b/lib/libaudit.h
@@ -34,6 +34,7 @@ extern "C" {
#include <linux/netlink.h>
#include <linux/audit.h>
#include <stdarg.h>
+#include <stdbool.h>
#include <syslog.h>


@@ -250,6 +251,10 @@ extern "C" {
#define AUDIT_CONTAINER_OP 1020 /* Container creation notice */
#endif

+#ifndef AUDIT_SIGNAL_INFO2
+#define AUDIT_SIGNAL_INFO2 1021 /* auditd signal sender info */
+#endif
+
#ifndef AUDIT_MMAP
#define AUDIT_MMAP 1323 /* Descriptor and flags in mmap */
#endif
@@ -499,7 +504,14 @@ extern "C" {
struct audit_sig_info {
uid_t uid;
pid_t pid;
- char ctx[0];
+ char ctx[];
+};
+
+struct audit_sig_info2 {
+ uid_t uid;
+ pid_t pid;
+ uint32_t cid_len;
+ char data[];
};

/* defines for audit subsystem */
@@ -527,6 +539,7 @@ struct audit_reply {
char *message;
struct nlmsgerr *error;
struct audit_sig_info *signal_info;
+ struct audit_sig_info2 *signal_info2;
struct daemon_conf *conf;
#ifdef AUDIT_FEATURE_BITMAP_ALL
struct audit_features *features;
@@ -604,6 +617,7 @@ 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);
+extern bool audit_signal_info_has_ctx(struct audit_reply *rep);
extern char *audit_format_signal_info(char *buf, int len, char *op, struct audit_reply *rep, char *res);

/* Translation functions */
diff --git a/lib/msg_typetab.h b/lib/msg_typetab.h
index 7490939c39a2..e904ece158ce 100644
--- a/lib/msg_typetab.h
+++ b/lib/msg_typetab.h
@@ -44,6 +44,7 @@ _S(AUDIT_LOGIN, "LOGIN" )
//_S(AUDIT_TTY_SET, "TTY_SET" )
//_S(AUDIT_SET_FEATURE, "SET_FEATURE" )
//_S(AUDIT_GET_FEATURE, "GET_FEATURE" )
+//_S(AUDIT_SIGNAL_INFO2, "SIGNAL_INFO2" )
_S(AUDIT_CONTAINER_OP, "CONTAINER_OP" )
_S(AUDIT_USER_AUTH, "USER_AUTH" )
_S(AUDIT_USER_ACCT, "USER_ACCT" )
diff --git a/lib/netlink.c b/lib/netlink.c
index caa963b1ddb2..66a3a3b7e83c 100644
--- a/lib/netlink.c
+++ b/lib/netlink.c
@@ -146,6 +146,7 @@ static int adjust_reply(struct audit_reply *rep, int len)
rep->message = NULL;
rep->error = NULL;
rep->signal_info = NULL;
+ rep->signal_info2 = NULL;
rep->conf = NULL;
#if defined(HAVE_DECL_AUDIT_FEATURE_VERSION) && \
defined(HAVE_STRUCT_AUDIT_STATUS_FEATURE_BITMAP)
@@ -194,6 +195,9 @@ static int adjust_reply(struct audit_reply *rep, int len)
case AUDIT_SIGNAL_INFO:
rep->signal_info = NLMSG_DATA(rep->nlh);
break;
+ case AUDIT_SIGNAL_INFO2:
+ rep->signal_info2 = NLMSG_DATA(rep->nlh);
+ break;
}
return len;
}
diff --git a/src/auditd-config.c b/src/auditd-config.c
index ce260de5025a..2a98a5f97e94 100644
--- a/src/auditd-config.c
+++ b/src/auditd-config.c
@@ -307,6 +307,7 @@ void clear_config(struct daemon_conf *config)
config->sender_uid = 0;
config->sender_pid = 0;
config->sender_ctx = NULL;
+ config->sender_cid = NULL;
config->write_logs = 1;
config->log_file = strdup("/var/log/audit/audit.log");
config->log_format = LF_ENRICHED;
diff --git a/src/auditd-config.h b/src/auditd-config.h
index 50ed3507d34c..4641c4e7223c 100644
--- a/src/auditd-config.h
+++ b/src/auditd-config.h
@@ -49,6 +49,7 @@ struct daemon_conf
uid_t sender_uid; /* the uid for sender of sighup */
pid_t sender_pid; /* the pid for sender of sighup */
const char *sender_ctx; /* the context for the sender of sighup */
+ const char *sender_cid; /* the contid for sender of sighup */
unsigned int write_logs;
const char *log_file;
logging_formats log_format;
diff --git a/src/auditd-event.c b/src/auditd-event.c
index 800f4d83bc83..9cb5d7a0efeb 100644
--- a/src/auditd-event.c
+++ b/src/auditd-event.c
@@ -1321,6 +1321,7 @@ static void reconfigure(struct auditd_event *e)
uid_t uid = nconf->sender_uid;
pid_t pid = nconf->sender_pid;
const char *ctx = nconf->sender_ctx;
+ const char *cid = nconf->sender_cid;
struct timeval tv;
char txt[MAX_AUDIT_MESSAGE_LENGTH];
int txt_len;
@@ -1331,8 +1332,11 @@ static void reconfigure(struct auditd_event *e)
txt_len = snprintf(txt, sizeof(txt),
"config change requested by pid=%d auid=%u", pid, uid);
if (ctx)
+ txt_len += snprintf(txt + txt_len, sizeof(txt) - txt_len,
+ " subj=%s", ctx);
+ if (cid)
snprintf(txt + txt_len, sizeof(txt) - txt_len,
- " subj=%s", ctx);
+ " contid=%s", cid);
audit_msg(LOG_NOTICE, "%s", txt);

/* Do the reconfiguring. These are done in a specific
@@ -1590,6 +1594,10 @@ static void reconfigure(struct auditd_event *e)
e->reply.len += snprintf(e->reply.msg.data + e->reply.len,
MAX_AUDIT_MESSAGE_LENGTH-2 - e->reply.len,
" res=success");
+ if (cid)
+ e->reply.len += snprintf(e->reply.msg.data + e->reply.len,
+ MAX_AUDIT_MESSAGE_LENGTH-2 - e->reply.len,
+ "contid=%s", cid);
e->reply.message = e->reply.msg.data;
free((char *)ctx);
}
diff --git a/src/auditd-reconfig.c b/src/auditd-reconfig.c
index 1af402526c4e..681f80adf925 100644
--- a/src/auditd-reconfig.c
+++ b/src/auditd-reconfig.c
@@ -101,11 +101,25 @@ static void *config_thread_main(void *arg)

if (load_config(&new_config, TEST_AUDITD) == 0) {
/* We will re-use the current reply */
- new_config.sender_uid = e->reply.signal_info->uid;
- new_config.sender_pid = e->reply.signal_info->pid;
- if (e->reply.len > 24)
- new_config.sender_ctx =
- strdup(e->reply.signal_info->ctx);
+ if (e->reply.type == AUDIT_SIGNAL_INFO) {
+ new_config.sender_uid = e->reply.signal_info->uid;
+ new_config.sender_pid = e->reply.signal_info->pid;
+ new_config.sender_cid = NULL;
+ } else {
+ new_config.sender_uid = e->reply.signal_info2->uid;
+ new_config.sender_pid = e->reply.signal_info2->pid;
+ new_config.sender_cid = strndup(e->reply.signal_info2->data,
+ e->reply.signal_info2->cid_len);
+ }
+ if (audit_signal_info_has_ctx(&e->reply)) {
+ if (e->reply.type == AUDIT_SIGNAL_INFO)
+ new_config.sender_ctx =
+ strdup(e->reply.signal_info->ctx);
+ else
+ new_config.sender_ctx =
+ strdup(e->reply.signal_info2->data +
+ e->reply.signal_info2->cid_len);
+ }
memcpy(e->reply.msg.data, &new_config, sizeof(new_config));
e->reply.conf = (struct daemon_conf *)e->reply.msg.data;
e->reply.type = AUDIT_DAEMON_RECONFIG;
@@ -125,4 +139,3 @@ static void *config_thread_main(void *arg)
pthread_mutex_unlock(&config_lock);
return NULL;
}
-
diff --git a/src/auditd.c b/src/auditd.c
index fa783a2cfa50..507e7711fb20 100644
--- a/src/auditd.c
+++ b/src/auditd.c
@@ -515,6 +515,7 @@ static void netlink_handler(struct ev_loop *loop, struct ev_io *io,
case AUDIT_REPLACE:
break;
case AUDIT_SIGNAL_INFO:
+ case AUDIT_SIGNAL_INFO2:
if (hup_info_requested) {
char hup[MAX_AUDIT_MESSAGE_LENGTH];
audit_msg(LOG_DEBUG,
@@ -1078,7 +1079,8 @@ static int get_reply(int rfd, struct audit_reply *rep, int seq)
continue;

/* If its not what we are expecting, keep looping */
- if (rep->type == AUDIT_SIGNAL_INFO)
+ if (rep->type == AUDIT_SIGNAL_INFO ||
+ rep->type == AUDIT_SIGNAL_INFO2)
return 1;

/* If we get done or error, break out */
--
1.8.3.1