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Invalidate child dirfd cache entries when their parent goes away

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If we don't do that, a directory could be removed from the cache, a new
directory with the same dirfd could be created, and the entries from the old
directory would appear in the new directory.
* src/safe.c (struct cached_dirfd): Keep track of the children of each dirfd
cache entry.
(remove_cached_dirfd): Remove all the entry's children from the lookup hash,
take them off the list of children, and initialize the children's
children_link.  Then, remove the entry itself from its parent. This has no
effect if the entry doesn't have a parent because then, children_link is empty.
(openat_cached): Add new dirfd cache entries to their parent's list of children
and initialize the entry's list of children.
(traverse_another_path): Also initialize cwd's list of children.
This commit is contained in:
Andreas Gruenbacher 2015-03-01 01:08:54 +01:00
parent c5705fd476
commit 914d06b7c3
1 changed files with 13 additions and 0 deletions
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13
src/safe.c
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@ -55,6 +55,7 @@ unsigned long dirfd_cache_misses;
struct cached_dirfd {
struct list_head lru_link;
struct list_head children_link, children;
struct cached_dirfd *parent;
char *name;
@ -124,6 +125,14 @@ static struct cached_dirfd *lookup_cached_dirfd (struct cached_dirfd *dir, const
static void remove_cached_dirfd (struct cached_dirfd *entry)
{
while (! list_empty (&entry->children))
{
struct cached_dirfd *child =
list_entry (entry->children.next, struct cached_dirfd, children_link);
list_del_init (&child->children_link);
hash_delete (cached_dirfds, child);
}
list_del (&entry->children_link);
list_del (&entry->lru_link);
hash_delete (cached_dirfds, entry);
free_cached_dirfd (entry);
@ -208,6 +217,8 @@ static struct cached_dirfd *openat_cached (struct cached_dirfd *dir, const char
/* Store new cache entry */
entry = xmalloc (sizeof (struct cached_dirfd));
INIT_LIST_HEAD (&entry->lru_link);
list_add (&entry->children_link, &dir->children);
INIT_LIST_HEAD (&entry->children);
entry->parent = dir;
entry->name = xstrdup (name);
entry->fd = fd;
@ -358,6 +369,8 @@ static int traverse_another_path (const char **pathname, int keepfd)
struct symlink *stack = NULL;
unsigned int steps = count_path_components (path);
INIT_LIST_HEAD (&cwd.children);
if (steps > MAX_PATH_COMPONENTS)
{
errno = ELOOP;