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path: root/fs/cifs/cifsacl.c
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-rw-r--r--fs/cifs/cifsacl.c138
1 files changed, 138 insertions, 0 deletions
diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c
index a0d11eab14e..061fc3afd84 100644
--- a/fs/cifs/cifsacl.c
+++ b/fs/cifs/cifsacl.c
@@ -23,6 +23,10 @@
#include <linux/fs.h>
#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/keyctl.h>
+#include <linux/key-type.h>
+#include <keys/user-type.h>
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifsacl.h"
@@ -50,6 +54,140 @@ static const struct cifs_sid sid_authusers = {
/* group users */
static const struct cifs_sid sid_user = {1, 2 , {0, 0, 0, 0, 0, 5}, {} };
+static const struct cred *root_cred;
+
+/*
+ * Run idmap cache shrinker.
+ */
+static int
+cifs_idmap_shrinker(struct shrinker *shrink, int nr_to_scan, gfp_t gfp_mask)
+{
+ /* Use a pruning scheme in a subsequent patch instead */
+ cifs_destroy_idmaptrees();
+ return 0;
+}
+
+static struct shrinker cifs_shrinker = {
+ .shrink = cifs_idmap_shrinker,
+ .seeks = DEFAULT_SEEKS,
+};
+
+static int
+cifs_idmap_key_instantiate(struct key *key, const void *data, size_t datalen)
+{
+ char *payload;
+
+ payload = kmalloc(datalen, GFP_KERNEL);
+ if (!payload)
+ return -ENOMEM;
+
+ memcpy(payload, data, datalen);
+ key->payload.data = payload;
+ return 0;
+}
+
+static inline void
+cifs_idmap_key_destroy(struct key *key)
+{
+ kfree(key->payload.data);
+}
+
+static
+struct key_type cifs_idmap_key_type = {
+ .name = "cifs.cifs_idmap",
+ .instantiate = cifs_idmap_key_instantiate,
+ .destroy = cifs_idmap_key_destroy,
+ .describe = user_describe,
+ .match = user_match,
+};
+
+int
+init_cifs_idmap(void)
+{
+ struct cred *cred;
+ struct key *keyring;
+ int ret;
+
+ cFYI(1, "Registering the %s key type\n", cifs_idmap_key_type.name);
+
+ /* create an override credential set with a special thread keyring in
+ * which requests are cached
+ *
+ * this is used to prevent malicious redirections from being installed
+ * with add_key().
+ */
+ cred = prepare_kernel_cred(NULL);
+ if (!cred)
+ return -ENOMEM;
+
+ keyring = key_alloc(&key_type_keyring, ".cifs_idmap", 0, 0, cred,
+ (KEY_POS_ALL & ~KEY_POS_SETATTR) |
+ KEY_USR_VIEW | KEY_USR_READ,
+ KEY_ALLOC_NOT_IN_QUOTA);
+ if (IS_ERR(keyring)) {
+ ret = PTR_ERR(keyring);
+ goto failed_put_cred;
+ }
+
+ ret = key_instantiate_and_link(keyring, NULL, 0, NULL, NULL);
+ if (ret < 0)
+ goto failed_put_key;
+
+ ret = register_key_type(&cifs_idmap_key_type);
+ if (ret < 0)
+ goto failed_put_key;
+
+ /* instruct request_key() to use this special keyring as a cache for
+ * the results it looks up */
+ cred->thread_keyring = keyring;
+ cred->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
+ root_cred = cred;
+
+ spin_lock_init(&siduidlock);
+ uidtree = RB_ROOT;
+ spin_lock_init(&sidgidlock);
+ gidtree = RB_ROOT;
+
+ register_shrinker(&cifs_shrinker);
+
+ cFYI(1, "cifs idmap keyring: %d\n", key_serial(keyring));
+ return 0;
+
+failed_put_key:
+ key_put(keyring);
+failed_put_cred:
+ put_cred(cred);
+ return ret;
+}
+
+void
+exit_cifs_idmap(void)
+{
+ key_revoke(root_cred->thread_keyring);
+ unregister_key_type(&cifs_idmap_key_type);
+ put_cred(root_cred);
+ unregister_shrinker(&cifs_shrinker);
+ cFYI(1, "Unregistered %s key type\n", cifs_idmap_key_type.name);
+}
+
+void
+cifs_destroy_idmaptrees(void)
+{
+ struct rb_root *root;
+ struct rb_node *node;
+
+ root = &uidtree;
+ spin_lock(&siduidlock);
+ while ((node = rb_first(root)))
+ rb_erase(node, root);
+ spin_unlock(&siduidlock);
+
+ root = &gidtree;
+ spin_lock(&sidgidlock);
+ while ((node = rb_first(root)))
+ rb_erase(node, root);
+ spin_unlock(&sidgidlock);
+}
int match_sid(struct cifs_sid *ctsid)
{