audit: replace getname()/putname() hacks with reference counters
In order to ensure that filenames are not released before the audit
subsystem is done with the strings there are a number of hacks built
into the fs and audit subsystems around getname() and putname(). To
say these hacks are "ugly" would be kind.
This patch removes the filename hackery in favor of a more
conventional reference count based approach. The diffstat below tells
most of the story; lots of audit/fs specific code is replaced with a
traditional reference count based approach that is easily understood,
even by those not familiar with the audit and/or fs subsystems.
CC: viro@zeniv.linux.org.uk
CC: linux-fsdevel@vger.kernel.org
Signed-off-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 4f52196..0c38604 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -866,33 +866,10 @@
{
struct audit_names *n, *next;
-#if AUDIT_DEBUG == 2
- if (context->put_count + context->ino_count != context->name_count) {
- int i = 0;
-
- pr_err("%s:%d(:%d): major=%d in_syscall=%d"
- " name_count=%d put_count=%d ino_count=%d"
- " [NOT freeing]\n", __FILE__, __LINE__,
- context->serial, context->major, context->in_syscall,
- context->name_count, context->put_count,
- context->ino_count);
- list_for_each_entry(n, &context->names_list, list) {
- pr_err("names[%d] = %p = %s\n", i++, n->name,
- n->name->name ?: "(null)");
- }
- dump_stack();
- return;
- }
-#endif
-#if AUDIT_DEBUG
- context->put_count = 0;
- context->ino_count = 0;
-#endif
-
list_for_each_entry_safe(n, next, &context->names_list, list) {
list_del(&n->list);
- if (n->name && n->name_put)
- final_putname(n->name);
+ if (n->name)
+ putname(n->name);
if (n->should_free)
kfree(n);
}
@@ -1711,9 +1688,6 @@
list_add_tail(&aname->list, &context->names_list);
context->name_count++;
-#if AUDIT_DEBUG
- context->ino_count++;
-#endif
return aname;
}
@@ -1734,8 +1708,10 @@
list_for_each_entry(n, &context->names_list, list) {
if (!n->name)
continue;
- if (n->name->uptr == uptr)
+ if (n->name->uptr == uptr) {
+ n->name->refcnt++;
return n->name;
+ }
}
return NULL;
}
@@ -1752,19 +1728,8 @@
struct audit_context *context = current->audit_context;
struct audit_names *n;
- if (!context->in_syscall) {
-#if AUDIT_DEBUG == 2
- pr_err("%s:%d(:%d): ignoring getname(%p)\n",
- __FILE__, __LINE__, context->serial, name);
- dump_stack();
-#endif
+ if (!context->in_syscall)
return;
- }
-
-#if AUDIT_DEBUG
- /* The filename _must_ have a populated ->name */
- BUG_ON(!name->name);
-#endif
n = audit_alloc_name(context, AUDIT_TYPE_UNKNOWN);
if (!n)
@@ -1772,56 +1737,13 @@
n->name = name;
n->name_len = AUDIT_NAME_FULL;
- n->name_put = true;
name->aname = n;
+ name->refcnt++;
if (!context->pwd.dentry)
get_fs_pwd(current->fs, &context->pwd);
}
-/* audit_putname - intercept a putname request
- * @name: name to intercept and delay for putname
- *
- * If we have stored the name from getname in the audit context,
- * then we delay the putname until syscall exit.
- * Called from include/linux/fs.h:putname().
- */
-void audit_putname(struct filename *name)
-{
- struct audit_context *context = current->audit_context;
-
- BUG_ON(!context);
- if (!name->aname || !context->in_syscall) {
-#if AUDIT_DEBUG == 2
- pr_err("%s:%d(:%d): final_putname(%p)\n",
- __FILE__, __LINE__, context->serial, name);
- if (context->name_count) {
- struct audit_names *n;
- int i = 0;
-
- list_for_each_entry(n, &context->names_list, list)
- pr_err("name[%d] = %p = %s\n", i++, n->name,
- n->name->name ?: "(null)");
- }
-#endif
- final_putname(name);
- }
-#if AUDIT_DEBUG
- else {
- ++context->put_count;
- if (context->put_count > context->name_count) {
- pr_err("%s:%d(:%d): major=%d in_syscall=%d putname(%p)"
- " name_count=%d put_count=%d\n",
- __FILE__, __LINE__,
- context->serial, context->major,
- context->in_syscall, name->name,
- context->name_count, context->put_count);
- dump_stack();
- }
- }
-#endif
-}
-
/**
* __audit_inode - store the inode and device from a lookup
* @name: name being audited
@@ -1842,11 +1764,6 @@
if (!name)
goto out_alloc;
-#if AUDIT_DEBUG
- /* The struct filename _must_ have a populated ->name */
- BUG_ON(!name->name);
-#endif
-
/*
* If we have a pointer to an audit_names entry already, then we can
* just use it directly if the type is correct.
@@ -1893,9 +1810,10 @@
n = audit_alloc_name(context, AUDIT_TYPE_UNKNOWN);
if (!n)
return;
- if (name)
- /* no need to set ->name_put as the original will cleanup */
+ if (name) {
n->name = name;
+ name->refcnt++;
+ }
out:
if (parent) {
@@ -2000,8 +1918,7 @@
if (found_parent) {
found_child->name = found_parent->name;
found_child->name_len = AUDIT_NAME_FULL;
- /* don't call __putname() */
- found_child->name_put = false;
+ found_child->name->refcnt++;
}
}