@@ -313,45 +313,43 @@ int fscrypt_decrypt_page(const struct inode *inode, struct page *page,
EXPORT_SYMBOL(fscrypt_decrypt_page);
/*
- * Validate dentries for encrypted directories to make sure we aren't
- * potentially caching stale data after a key has been added or
- * removed.
+ * Validate dentries in encrypted directories to make sure we aren't potentially
+ * caching stale dentries after a key has been added.
*/
static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
{
struct dentry *dir;
- int dir_has_key, cached_with_key;
+ int err;
+ int valid;
+
+ /*
+ * Plaintext names are always valid, since fscrypt doesn't support
+ * reverting to ciphertext names without evicting the directory's inode
+ * -- which implies eviction of the dentries in the directory.
+ */
+ if (!(dentry->d_flags & DCACHE_ENCRYPTED_NAME))
+ return 1;
+
+ /*
+ * Ciphertext name; valid if the directory's key is still unavailable.
+ *
+ * Note: since fscrypt forbids rename() on ciphertext names, it should
+ * be safe to access ->d_parent directly here. But use dget_parent() to
+ * be on the safe side.
+ */
if (flags & LOOKUP_RCU)
return -ECHILD;
dir = dget_parent(dentry);
- if (!IS_ENCRYPTED(d_inode(dir))) {
- dput(dir);
- return 0;
- }
-
- spin_lock(&dentry->d_lock);
- cached_with_key = dentry->d_flags & DCACHE_ENCRYPTED_WITH_KEY;
- spin_unlock(&dentry->d_lock);
- dir_has_key = (d_inode(dir)->i_crypt_info != NULL);
+ err = fscrypt_get_encryption_info(d_inode(dir));
+ valid = (d_inode(dir)->i_crypt_info == NULL);
dput(dir);
- /*
- * If the dentry was cached without the key, and it is a
- * negative dentry, it might be a valid name. We can't check
- * if the key has since been made available due to locking
- * reasons, so we fail the validation so ext4_lookup() can do
- * this check.
- *
- * We also fail the validation if the dentry was created with
- * the key present, but we no longer have the key, or vice versa.
- */
- if ((!cached_with_key && d_is_negative(dentry)) ||
- (!cached_with_key && dir_has_key) ||
- (cached_with_key && !dir_has_key))
- return 0;
- return 1;
+ if (err < 0)
+ return err;
+
+ return valid;
}
const struct dentry_operations fscrypt_d_ops = {
@@ -101,9 +101,9 @@ int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry)
if (err)
return err;
- if (fscrypt_has_encryption_key(dir)) {
+ if (!fscrypt_has_encryption_key(dir)) {
spin_lock(&dentry->d_lock);
- dentry->d_flags |= DCACHE_ENCRYPTED_WITH_KEY;
+ dentry->d_flags |= DCACHE_ENCRYPTED_NAME;
spin_unlock(&dentry->d_lock);
}
@@ -212,7 +212,7 @@ struct dentry_operations {
#define DCACHE_MAY_FREE 0x00800000
#define DCACHE_FALLTHRU 0x01000000 /* Fall through to lower layer */
-#define DCACHE_ENCRYPTED_WITH_KEY 0x02000000 /* dir is encrypted with a valid key */
+#define DCACHE_ENCRYPTED_NAME 0x02000000 /* Encrypted name (dir key was unavailable) */
#define DCACHE_OP_REAL 0x04000000
#define DCACHE_PAR_LOOKUP 0x10000000 /* being looked up (with parent locked shared) */
@@ -545,10 +545,8 @@ static inline int fscrypt_prepare_rename(struct inode *old_dir,
* filenames are presented in encrypted form. Therefore, we'll try to set up
* the directory's encryption key, but even without it the lookup can continue.
*
- * To allow invalidating stale dentries if the directory's encryption key is
- * added later, we also install a custom ->d_revalidate() method and use the
- * DCACHE_ENCRYPTED_WITH_KEY flag to indicate whether a given dentry is a
- * plaintext name (flag set) or a ciphertext name (flag cleared).
+ * This also installs a custom ->d_revalidate() method which will invalidate the
+ * dentry if it was created without the key and the key is later added.
*
* Return: 0 on success, -errno if a problem occurred while setting up the
* encryption key