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audit: store the auditd PID as a pid struct instead of pid_t

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This is arguably the right thing to do, and will make it easier when
we start supporting multiple audit daemons in different namespaces.

Signed-off-by: Paul Moore <paul@paul-moore.com>
This commit is contained in:
Paul Moore 2017-05-02 10:16:05 -04:00
parent 45a0642b4d
commit b6c7c115c2
2 changed files with 58 additions and 28 deletions
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84
kernel/audit.c
View file

@ -58,6 +58,7 @@
#include <linux/rcupdate.h>
#include <linux/mutex.h>
#include <linux/gfp.h>
#include <linux/pid.h>
#include <linux/audit.h>
@ -117,7 +118,7 @@ struct audit_net {
* or the included spinlock for writing.
*/
static struct auditd_connection {
int pid;
struct pid *pid;
u32 portid;
struct net *net;
spinlock_t lock;
@ -220,17 +221,40 @@ struct audit_reply {
* Description:
* Return 1 if the task is a registered audit daemon, 0 otherwise.
*/
int auditd_test_task(const struct task_struct *task)
int auditd_test_task(struct task_struct *task)
{
int rc;
rcu_read_lock();
rc = (auditd_conn.pid && task->tgid == auditd_conn.pid ? 1 : 0);
rc = (auditd_conn.pid && auditd_conn.pid == task_tgid(task) ? 1 : 0);
rcu_read_unlock();
return rc;
}
/**
* auditd_pid_vnr - Return the auditd PID relative to the namespace
* @auditd: the auditd connection
*
* Description:
* Returns the PID in relation to the namespace, 0 on failure. This function
* takes the RCU read lock internally, but if the caller needs to protect the
* auditd_connection pointer it should take the RCU read lock as well.
*/
static pid_t auditd_pid_vnr(const struct auditd_connection *auditd)
{
pid_t pid;
rcu_read_lock();
if (!auditd || !auditd->pid)
pid = 0;
else
pid = pid_vnr(auditd->pid);
rcu_read_unlock();
return pid;
}
/**
* audit_get_sk - Return the audit socket for the given network namespace
* @net: the destination network namespace
@ -428,12 +452,17 @@ static int audit_set_failure(u32 state)
* This function will obtain and drop network namespace references as
* necessary.
*/
static void auditd_set(int pid, u32 portid, struct net *net)
static void auditd_set(struct pid *pid, u32 portid, struct net *net)
{
unsigned long flags;
spin_lock_irqsave(&auditd_conn.lock, flags);
auditd_conn.pid = pid;
if (auditd_conn.pid)
put_pid(auditd_conn.pid);
if (pid)
auditd_conn.pid = get_pid(pid);
else
auditd_conn.pid = NULL;
auditd_conn.portid = portid;
if (auditd_conn.net)
put_net(auditd_conn.net);
@ -1059,11 +1088,13 @@ static int audit_set_feature(struct sk_buff *skb)
return 0;
}
static int audit_replace(pid_t pid)
static int audit_replace(struct pid *pid)
{
pid_t pvnr;
struct sk_buff *skb;
skb = audit_make_reply(0, AUDIT_REPLACE, 0, 0, &pid, sizeof(pid));
pvnr = pid_vnr(pid);
skb = audit_make_reply(0, AUDIT_REPLACE, 0, 0, &pvnr, sizeof(pvnr));
if (!skb)
return -ENOMEM;
return auditd_send_unicast_skb(skb);
@ -1093,9 +1124,9 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
memset(&s, 0, sizeof(s));
s.enabled = audit_enabled;
s.failure = audit_failure;
rcu_read_lock();
s.pid = auditd_conn.pid;
rcu_read_unlock();
/* NOTE: use pid_vnr() so the PID is relative to the current
* namespace */
s.pid = auditd_pid_vnr(&auditd_conn);
s.rate_limit = audit_rate_limit;
s.backlog_limit = audit_backlog_limit;
s.lost = atomic_read(&audit_lost);
@ -1121,36 +1152,36 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
return err;
}
if (s.mask & AUDIT_STATUS_PID) {
/* NOTE: we are using task_tgid_vnr() below because
* the s.pid value is relative to the namespace
* of the caller; at present this doesn't matter
* much since you can really only run auditd
* from the initial pid namespace, but something
* to keep in mind if this changes */
int new_pid = s.pid;
/* NOTE: we are using the vnr PID functions below
* because the s.pid value is relative to the
* namespace of the caller; at present this
* doesn't matter much since you can really only
* run auditd from the initial pid namespace, but
* something to keep in mind if this changes */
pid_t new_pid = s.pid;
pid_t auditd_pid;
pid_t requesting_pid = task_tgid_vnr(current);
struct pid *req_pid = task_tgid(current);
/* sanity check - PID values must match */
if (new_pid != pid_vnr(req_pid))
return -EINVAL;
/* test the auditd connection */
audit_replace(requesting_pid);
audit_replace(req_pid);
rcu_read_lock();
auditd_pid = auditd_conn.pid;
auditd_pid = auditd_pid_vnr(&auditd_conn);
/* only the current auditd can unregister itself */
if ((!new_pid) && (requesting_pid != auditd_pid)) {
rcu_read_unlock();
if ((!new_pid) && (new_pid != auditd_pid)) {
audit_log_config_change("audit_pid", new_pid,
auditd_pid, 0);
return -EACCES;
}
/* replacing a healthy auditd is not allowed */
if (auditd_pid && new_pid) {
rcu_read_unlock();
audit_log_config_change("audit_pid", new_pid,
auditd_pid, 0);
return -EEXIST;
}
rcu_read_unlock();
if (audit_enabled != AUDIT_OFF)
audit_log_config_change("audit_pid", new_pid,
@ -1158,8 +1189,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
if (new_pid) {
/* register a new auditd connection */
auditd_set(new_pid,
NETLINK_CB(skb).portid,
auditd_set(req_pid, NETLINK_CB(skb).portid,
sock_net(NETLINK_CB(skb).sk));
/* try to process any backlog */
wake_up_interruptible(&kauditd_wait);

2
kernel/audit.h
View file

@ -218,7 +218,7 @@ extern void audit_log_name(struct audit_context *context,
struct audit_names *n, const struct path *path,
int record_num, int *call_panic);
extern int auditd_test_task(const struct task_struct *task);
extern int auditd_test_task(struct task_struct *task);
#define AUDIT_INODE_BUCKETS 32
extern struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];