[PATCH AUTOSEL 5.0 238/262] audit: hand taken context to audit_kill_trees for syscall logging

Sasha Levin
2019-03-27T19:14:33Z

From: Richard Guy Briggs <rgb@redhat.com>

[ Upstream commit 9e36a5d49c3a6fc4a2e0ba2dc11b27c4a8ae6303 ]

Since the context is derived from the task parameter handed to
__audit_free(), hand the context to audit_kill_trees() so it can be used
to associate with a syscall record. This requires adding the context
parameter to kill_rules() rather than using the current audit_context.

The callers of trim_marked() and evict_chunk() still have their context.

The EOE record was being issued prior to the pruning of the killed_tree
list.

Move the kill_trees call before the audit_log_exit call in
__audit_free() and __audit_syscall_exit() so that any pruned trees
CONFIG_CHANGE records are included with the associated syscall event by
the user library due to the EOE record flagging the end of the event.

See: https://github.com/linux-audit/audit-kernel/issues/50
See: https://github.com/linux-audit/audit-kernel/issues/59

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[PM: fixed merge fuzz in kernel/audit_tree.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/audit.h | 4 ++--
kernel/audit_tree.c | 19 +++++++++++--------
kernel/auditsc.c | 12 ++++++------
3 files changed, 19 insertions(+), 16 deletions(-)

diff --git a/kernel/audit.h b/kernel/audit.h
index 91421679a168..6ffb70575082 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -314,7 +314,7 @@ extern void audit_trim_trees(void);
extern int audit_tag_tree(char *old, char *new);
extern const char *audit_tree_path(struct audit_tree *tree);
extern void audit_put_tree(struct audit_tree *tree);
-extern void audit_kill_trees(struct list_head *list);
+extern void audit_kill_trees(struct audit_context *context);
#else
#define audit_remove_tree_rule(rule) BUG()
#define audit_add_tree_rule(rule) -EINVAL
@@ -323,7 +323,7 @@ extern void audit_kill_trees(struct list_head *list);
#define audit_put_tree(tree) (void)0
#define audit_tag_tree(old, new) -EINVAL
#define audit_tree_path(rule) "" /* never called */
-#define audit_kill_trees(list) BUG()
+#define audit_kill_trees(context) BUG()
#endif

extern char *audit_unpack_string(void **bufp, size_t *remain, size_t len);
diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
index d4af4d97f847..abfb112f26aa 100644
--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -524,13 +524,14 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
return 0;
}

-static void audit_tree_log_remove_rule(struct audit_krule *rule)
+static void audit_tree_log_remove_rule(struct audit_context *context,
+ struct audit_krule *rule)
{
struct audit_buffer *ab;

if (!audit_enabled)
return;
- ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
+ ab = audit_log_start(context, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
if (unlikely(!ab))
return;
audit_log_format(ab, "op=remove_rule dir=");
@@ -540,7 +541,7 @@ static void audit_tree_log_remove_rule(struct audit_krule *rule)
audit_log_end(ab);
}

-static void kill_rules(struct audit_tree *tree)
+static void kill_rules(struct audit_context *context, struct audit_tree *tree)
{
struct audit_krule *rule, *next;
struct audit_entry *entry;
@@ -551,7 +552,7 @@ static void kill_rules(struct audit_tree *tree)
list_del_init(&rule->rlist);
if (rule->tree) {
/* not a half-baked one */
- audit_tree_log_remove_rule(rule);
+ audit_tree_log_remove_rule(context, rule);
if (entry->rule.exe)
audit_remove_mark(entry->rule.exe);
rule->tree = NULL;
@@ -633,7 +634,7 @@ static void trim_marked(struct audit_tree *tree)
tree->goner = 1;
spin_unlock(&hash_lock);
mutex_lock(&audit_filter_mutex);
- kill_rules(tree);
+ kill_rules(audit_context(), tree);
list_del_init(&tree->list);
mutex_unlock(&audit_filter_mutex);
prune_one(tree);
@@ -973,8 +974,10 @@ static void audit_schedule_prune(void)
* ... and that one is done if evict_chunk() decides to delay until the end
* of syscall. Runs synchronously.
*/
-void audit_kill_trees(struct list_head *list)
+void audit_kill_trees(struct audit_context *context)
{
+ struct list_head *list = &context->killed_trees;
+
audit_ctl_lock();
mutex_lock(&audit_filter_mutex);

@@ -982,7 +985,7 @@ void audit_kill_trees(struct list_head *list)
struct audit_tree *victim;

victim = list_entry(list->next, struct audit_tree, list);
- kill_rules(victim);
+ kill_rules(context, victim);
list_del_init(&victim->list);

mutex_unlock(&audit_filter_mutex);
@@ -1017,7 +1020,7 @@ static void evict_chunk(struct audit_chunk *chunk)
list_del_init(&owner->same_root);
spin_unlock(&hash_lock);
if (!postponed) {
- kill_rules(owner);
+ kill_rules(audit_context(), owner);
list_move(&owner->list, &prune_list);
need_prune = 1;
} else {
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 6593a5207fb0..b585ceb2f7a2 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1444,6 +1444,9 @@ void __audit_free(struct task_struct *tsk)
if (!context)
return;

+ if (!list_empty(&context->killed_trees))
+ audit_kill_trees(context);
+
/* We are called either by do_exit() or the fork() error handling code;
* in the former case tsk == current and in the latter tsk is a
* random task_struct that doesn't doesn't have any meaningful data we
@@ -1460,9 +1463,6 @@ void __audit_free(struct task_struct *tsk)
audit_log_exit();
}

- if (!list_empty(&context->killed_trees))
- audit_kill_trees(&context->killed_trees);
-
audit_set_context(tsk, NULL);
audit_free_context(context);
}
@@ -1537,6 +1537,9 @@ void __audit_syscall_exit(int success, long return_code)
if (!context)
return;

+ if (!list_empty(&context->killed_trees))
+ audit_kill_trees(context);
+
if (!context->dummy && context->in_syscall) {
if (success)
context->return_valid = AUDITSC_SUCCESS;
@@ -1571,9 +1574,6 @@ void __audit_syscall_exit(int success, long return_code)
context->in_syscall = 0;
context->prio = context->state == AUDIT_RECORD_CONTEXT ? ~0ULL : 0;

- if (!list_empty(&context->killed_trees))
- audit_kill_trees(&context->killed_trees);
-
audit_free_names(context);
unroll_tree_refs(context, NULL, 0);
audit_free_aux(context);
--
2.19.1