deadlock fixes
Alexander Viro
aviro at redhat.com
Thu Apr 27 12:28:32 UTC 2006
On Thu, Apr 27, 2006 at 07:27:25AM -0400, Alexander Viro wrote:
> handling, as discussed on IRC yesterday.
Patch in question (thanks to Steve for reminding to send it to list):
diff --git a/kernel/audit.c b/kernel/audit.c
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -368,6 +368,46 @@ static int kauditd_thread(void *dummy)
return 0;
}
+int audit_send_list(void *_dest)
+{
+ struct audit_netlink_list *dest = _dest;
+ int pid = dest->pid;
+ struct sk_buff *skb;
+
+ while ((skb = __skb_dequeue(&dest->q)) != NULL)
+ netlink_unicast(audit_sock, skb, pid, 0);
+
+ kfree(dest);
+
+ return 0;
+}
+
+struct sk_buff *audit_make_reply(int pid, int seq, int type, int done,
+ int multi, void *payload, int size)
+{
+ struct sk_buff *skb;
+ struct nlmsghdr *nlh;
+ int len = NLMSG_SPACE(size);
+ void *data;
+ int flags = multi ? NLM_F_MULTI : 0;
+ int t = done ? NLMSG_DONE : type;
+
+ skb = alloc_skb(len, GFP_KERNEL);
+ if (!skb)
+ return NULL;
+
+ nlh = NLMSG_PUT(skb, pid, seq, t, size);
+ nlh->nlmsg_flags = flags;
+ data = NLMSG_DATA(nlh);
+ memcpy(data, payload, size);
+ return skb;
+
+nlmsg_failure: /* Used by NLMSG_PUT */
+ if (skb)
+ kfree_skb(skb);
+ return NULL;
+}
+
/**
* audit_send_reply - send an audit reply message via netlink
* @pid: process id to send reply to
@@ -385,29 +425,13 @@ void audit_send_reply(int pid, int seq,
void *payload, int size)
{
struct sk_buff *skb;
- struct nlmsghdr *nlh;
- int len = NLMSG_SPACE(size);
- void *data;
- int flags = multi ? NLM_F_MULTI : 0;
- int t = done ? NLMSG_DONE : type;
-
- skb = alloc_skb(len, GFP_KERNEL);
+ skb = audit_make_reply(pid, seq, type, done, multi, payload, size);
if (!skb)
return;
-
- nlh = NLMSG_PUT(skb, pid, seq, t, size);
- nlh->nlmsg_flags = flags;
- data = NLMSG_DATA(nlh);
- memcpy(data, payload, size);
-
/* Ignore failure. It'll only happen if the sender goes away,
because our timeout is set to infinite. */
netlink_unicast(audit_sock, skb, pid, 0);
return;
-
-nlmsg_failure: /* Used by NLMSG_PUT */
- if (skb)
- kfree_skb(skb);
}
/*
diff --git a/kernel/audit.h b/kernel/audit.h
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -95,12 +95,22 @@ struct audit_entry {
extern int audit_pid;
extern int audit_comparator(const u32 left, const u32 op, const u32 right);
extern int audit_compare_dname_path(const char *dname, const char *path);
+extern struct sk_buff * audit_make_reply(int pid, int seq, int type,
+ int done, int multi,
+ void *payload, int size);
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 void audit_panic(const char *message);
+struct audit_netlink_list {
+ int pid;
+ struct sk_buff_head q;
+};
+
+int audit_send_list(void *);
+
struct inotify_watch;
extern void audit_handle_ievent(struct inotify_watch *, u32, u32, u32,
const char *, struct inode *);
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -1065,19 +1065,12 @@ static inline int audit_del_rule(struct
/* List rules using struct audit_rule. Exists for backward
* compatibility with userspace. */
-static int audit_list(void *_dest)
+static void audit_list(int pid, int seq, struct sk_buff_head *q)
{
- int pid, seq;
- int *dest = _dest;
+ struct sk_buff *skb;
struct audit_entry *entry;
int i;
- pid = dest[0];
- seq = dest[1];
- kfree(dest);
-
- mutex_lock(&audit_filter_mutex);
-
/* This is a blocking read, so use audit_filter_mutex instead of rcu
* iterator to sync with list writers. */
for (i=0; i<AUDIT_NR_FILTERS; i++) {
@@ -1087,31 +1080,25 @@ static int audit_list(void *_dest)
rule = audit_krule_to_rule(&entry->rule);
if (unlikely(!rule))
break;
- audit_send_reply(pid, seq, AUDIT_LIST, 0, 1,
+ skb = audit_make_reply(pid, seq, AUDIT_LIST, 0, 1,
rule, sizeof(*rule));
+ if (skb)
+ skb_queue_tail(q, skb);
kfree(rule);
}
}
- audit_send_reply(pid, seq, AUDIT_LIST, 1, 1, NULL, 0);
-
- mutex_unlock(&audit_filter_mutex);
- return 0;
+ skb = audit_make_reply(pid, seq, AUDIT_LIST, 1, 1, NULL, 0);
+ if (skb)
+ skb_queue_tail(q, skb);
}
/* List rules using struct audit_rule_data. */
-static int audit_list_rules(void *_dest)
+static void audit_list_rules(int pid, int seq, struct sk_buff_head *q)
{
- int pid, seq;
- int *dest = _dest;
+ struct sk_buff *skb;
struct audit_entry *e;
int i;
- pid = dest[0];
- seq = dest[1];
- kfree(dest);
-
- mutex_lock(&audit_filter_mutex);
-
/* This is a blocking read, so use audit_filter_mutex instead of rcu
* iterator to sync with list writers. */
for (i=0; i<AUDIT_NR_FILTERS; i++) {
@@ -1121,15 +1108,16 @@ static int audit_list_rules(void *_dest)
data = audit_krule_to_data(&e->rule);
if (unlikely(!data))
break;
- audit_send_reply(pid, seq, AUDIT_LIST_RULES, 0, 1,
+ skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 0, 1,
data, sizeof(*data) + data->buflen);
+ if (skb)
+ skb_queue_tail(q, skb);
kfree(data);
}
}
- audit_send_reply(pid, seq, AUDIT_LIST_RULES, 1, 1, NULL, 0);
-
- mutex_unlock(&audit_filter_mutex);
- return 0;
+ skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 1, 1, NULL, 0);
+ if (skb)
+ skb_queue_tail(q, skb);
}
/**
@@ -1147,7 +1135,7 @@ int audit_receive_filter(int type, int p
size_t datasz, uid_t loginuid, u32 sid)
{
struct task_struct *tsk;
- int *dest;
+ struct audit_netlink_list *dest;
int err = 0;
struct audit_entry *entry;
@@ -1160,18 +1148,22 @@ int audit_receive_filter(int type, int p
* happen if we're actually running in the context of auditctl
* trying to _send_ the stuff */
- dest = kmalloc(2 * sizeof(int), GFP_KERNEL);
+ dest = kmalloc(sizeof(struct audit_netlink_list), GFP_KERNEL);
if (!dest)
return -ENOMEM;
- dest[0] = pid;
- dest[1] = seq;
+ dest->pid = pid;
+ skb_queue_head_init(&dest->q);
+ mutex_lock(&audit_filter_mutex);
if (type == AUDIT_LIST)
- tsk = kthread_run(audit_list, dest, "audit_list");
+ audit_list(pid, seq, &dest->q);
else
- tsk = kthread_run(audit_list_rules, dest,
- "audit_list_rules");
+ audit_list_rules(pid, seq, &dest->q);
+ mutex_unlock(&audit_filter_mutex);
+
+ tsk = kthread_run(audit_send_list, dest, "audit_send_list");
if (IS_ERR(tsk)) {
+ skb_queue_purge(&dest->q);
kfree(dest);
err = PTR_ERR(tsk);
}
--
0.99.9.GIT
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