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authorDavid Woodhouse <dwmw2@shinybook.infradead.org>2005-06-21 16:22:01 +0100
committerDavid Woodhouse <dwmw2@shinybook.infradead.org>2005-06-21 16:22:01 +0100
commitf6a789d19858a951e7ff9e297a44b377c21b6c33 (patch)
tree5e54f1460bc048706ad6df8c5cb5bf748f067f13
parentae7b961b1c943367dfe179411f120d7bf8eaba89 (diff)
AUDIT: Spawn kernel thread to list filter rules.
If we have enough rules to fill the netlink buffer space, it'll deadlock because auditctl isn't ever actually going to read from the socket until we return, and we aren't going to return until it reads... so we spawn a kernel thread to spew out the list and then exit. Signed-off-by: David Woodhouse <dwmw2@infradead.org>
-rw-r--r--include/linux/audit.h1
-rw-r--r--kernel/audit.c2
-rw-r--r--kernel/auditsc.c53
3 files changed, 47 insertions, 9 deletions
diff --git a/include/linux/audit.h b/include/linux/audit.h
index 5f812e4d01e..5d1a9dda5ac 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -281,6 +281,7 @@ extern void audit_send_reply(int pid, int seq, int type,
int done, int multi,
void *payload, int size);
extern void audit_log_lost(const char *message);
+extern struct semaphore audit_netlink_sem;
#else
#define audit_log(c,t,f,...) do { ; } while (0)
#define audit_log_start(c,t) ({ NULL; })
diff --git a/kernel/audit.c b/kernel/audit.c
index ab6ac560cfe..c1ab8dbbb67 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -110,7 +110,7 @@ static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait);
/* The netlink socket is only to be read by 1 CPU, which lets us assume
* that list additions and deletions never happen simultaneously in
* auditsc.c */
-static DECLARE_MUTEX(audit_netlink_sem);
+DECLARE_MUTEX(audit_netlink_sem);
/* AUDIT_BUFSIZ is the size of the temporary buffer used for formatting
* audit records. Since printk uses a 1024 byte buffer, this buffer
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 031f979019d..cb8a4494515 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -39,6 +39,7 @@
#include <linux/audit.h>
#include <linux/personality.h>
#include <linux/time.h>
+#include <linux/kthread.h>
#include <asm/unistd.h>
/* 0 = no checking
@@ -281,24 +282,60 @@ static int audit_copy_rule(struct audit_rule *d, struct audit_rule *s)
return 0;
}
+static int audit_list_rules(void *_dest)
+{
+ int pid, seq;
+ int *dest = _dest;
+ struct audit_entry *entry;
+ int i;
+
+ pid = dest[0];
+ seq = dest[1];
+ kfree(dest);
+
+ down(&audit_netlink_sem);
+
+ /* The *_rcu iterators not needed here because we are
+ always called with audit_netlink_sem held. */
+ for (i=0; i<AUDIT_NR_FILTERS; i++) {
+ list_for_each_entry(entry, &audit_filter_list[i], list)
+ audit_send_reply(pid, seq, AUDIT_LIST, 0, 1,
+ &entry->rule, sizeof(entry->rule));
+ }
+ audit_send_reply(pid, seq, AUDIT_LIST, 1, 1, NULL, 0);
+
+ up(&audit_netlink_sem);
+ return 0;
+}
+
int audit_receive_filter(int type, int pid, int uid, int seq, void *data,
uid_t loginuid)
{
struct audit_entry *entry;
+ struct task_struct *tsk;
+ int *dest;
int err = 0;
- int i;
unsigned listnr;
switch (type) {
case AUDIT_LIST:
- /* The *_rcu iterators not needed here because we are
- always called with audit_netlink_sem held. */
- for (i=0; i<AUDIT_NR_FILTERS; i++) {
- list_for_each_entry(entry, &audit_filter_list[i], list)
- audit_send_reply(pid, seq, AUDIT_LIST, 0, 1,
- &entry->rule, sizeof(entry->rule));
+ /* We can't just spew out the rules here because we might fill
+ * the available socket buffer space and deadlock waiting for
+ * auditctl to read from it... which isn't ever going to
+ * happen if we're actually running in the context of auditctl
+ * trying to _send_ the stuff */
+
+ dest = kmalloc(2 * sizeof(int), GFP_KERNEL);
+ if (!dest)
+ return -ENOMEM;
+ dest[0] = pid;
+ dest[1] = seq;
+
+ tsk = kthread_run(audit_list_rules, dest, "audit_list_rules");
+ if (IS_ERR(tsk)) {
+ kfree(dest);
+ err = PTR_ERR(tsk);
}
- audit_send_reply(pid, seq, AUDIT_LIST, 1, 1, NULL, 0);
break;
case AUDIT_ADD:
if (!(entry = kmalloc(sizeof(*entry), GFP_KERNEL)))