Merge tag 'renesas-sh-drivers-fixes-for-v4.5' of git://git.kernel.org/pub/scm/linux...

[cascardo/linux.git] / fs / ext4 / crypto.c

diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
index c802120..38f7562 100644 (file)
--- a/fs/ext4/crypto.c
+++ b/fs/ext4/crypto.c
@@ -467,3 +467,59 @@ uint32_t ext4_validate_encryption_key_size(uint32_t mode, uint32_t size)
                return size;
        return 0;
 }
+
+/*
+ * Validate dentries for encrypted directories to make sure we aren't
+ * potentially caching stale data after a key has been added or
+ * removed.
+ */
+static int ext4_d_revalidate(struct dentry *dentry, unsigned int flags)
+{
+       struct inode *dir = d_inode(dentry->d_parent);
+       struct ext4_crypt_info *ci = EXT4_I(dir)->i_crypt_info;
+       int dir_has_key, cached_with_key;
+
+       if (!ext4_encrypted_inode(dir))
+               return 0;
+
+       if (ci && ci->ci_keyring_key &&
+           (ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) |
+                                         (1 << KEY_FLAG_REVOKED) |
+                                         (1 << KEY_FLAG_DEAD))))
+               ci = NULL;
+
+       /* this should eventually be an flag in d_flags */
+       cached_with_key = dentry->d_fsdata != NULL;
+       dir_has_key = (ci != NULL);
+
+       /*
+        * 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)) {
+#if 0                          /* Revalidation debug */
+               char buf[80];
+               char *cp = simple_dname(dentry, buf, sizeof(buf));
+
+               if (IS_ERR(cp))
+                       cp = (char *) "???";
+               pr_err("revalidate: %s %p %d %d %d\n", cp, dentry->d_fsdata,
+                      cached_with_key, d_is_negative(dentry),
+                      dir_has_key);
+#endif
+               return 0;
+       }
+       return 1;
+}
+
+const struct dentry_operations ext4_encrypted_d_ops = {
+       .d_revalidate = ext4_d_revalidate,
+};