Merge tag 'ecryptfs-4.17-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tyhicks/ecryptfs

Pull eCryptfs fixes from Tyler Hicks:
 "Minor cleanups and a bug fix to completely ignore unencrypted
  filenames in the lower filesystem when filename encryption is enabled
  at the eCryptfs layer"

* tag 'ecryptfs-4.17-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tyhicks/ecryptfs:
  eCryptfs: don't pass up plaintext names when using filename encryption
  ecryptfs: fix spelling mistake: "cadidate" -> "candidate"
  ecryptfs: lookup: Don't check if mount_crypt_stat is NULL

4 files changed, 46 insertions, 21 deletions

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 846ca150d52e..4dd842f72846 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -1997,6 +1997,16 @@ out:
         return rc;
 }
 
+static bool is_dot_dotdot(const char *name, size_t name_size)
+{
+        if (name_size == 1 && name[0] == '.')
+                return true;
+        else if (name_size == 2 && name[0] == '.' && name[1] == '.')
+                return true;
+
+        return false;
+}
+
 /**
  * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
  * @plaintext_name: The plaintext name
@@ -2021,13 +2031,21 @@ int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
         size_t packet_size;
         int rc = 0;
 
-        if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
-            && !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
-            && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
-            && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
-                        ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
-                const char *orig_name = name;
-                size_t orig_name_size = name_size;
+        if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) &&
+            !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)) {
+                if (is_dot_dotdot(name, name_size)) {
+                        rc = ecryptfs_copy_filename(plaintext_name,
+                                                    plaintext_name_size,
+                                                    name, name_size);
+                        goto out;
+                }
+
+                if (name_size <= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE ||
+                    strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
+                            ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)) {
+                        rc = -EINVAL;
+                        goto out;
+                }
 
                 name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
                 name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
@@ -2047,12 +2065,9 @@ int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
                                                   decoded_name,
                                                   decoded_name_size);
                 if (rc) {
-                        printk(KERN_INFO "%s: Could not parse tag 70 packet "
-                               "from filename; copying through filename "
-                               "as-is\n", __func__);
-                        rc = ecryptfs_copy_filename(plaintext_name,
-                                                    plaintext_name_size,
-                                                    orig_name, orig_name_size);
+                        ecryptfs_printk(KERN_DEBUG,
+                                        "%s: Could not parse tag 70 packet from filename\n",
+                                        __func__);
                         goto out_free;
                 }
         } else {
diff --git a/fs/ecryptfs/file.c b/fs/ecryptfs/file.c
index c74ed3ca3372..b76a9853325e 100644
--- a/fs/ecryptfs/file.c
+++ b/fs/ecryptfs/file.c
@@ -82,17 +82,28 @@ ecryptfs_filldir(struct dir_context *ctx, const char *lower_name,
                                                   buf->sb, lower_name,
                                                   lower_namelen);
         if (rc) {
-                printk(KERN_ERR "%s: Error attempting to decode and decrypt "
-                       "filename [%s]; rc = [%d]\n", __func__, lower_name,
-                       rc);
-                goto out;
+                if (rc != -EINVAL) {
+                        ecryptfs_printk(KERN_DEBUG,
+                                        "%s: Error attempting to decode and decrypt filename [%s]; rc = [%d]\n",
+                                        __func__, lower_name, rc);
+                        return rc;
+                }
+
+                /* Mask -EINVAL errors as these are most likely due a plaintext
+                 * filename present in the lower filesystem despite filename
+                 * encryption being enabled. One unavoidable example would be
+                 * the "lost+found" dentry in the root directory of an Ext4
+                 * filesystem.
+                 */
+                return 0;
         }
+
         buf->caller->pos = buf->ctx.pos;
         rc = !dir_emit(buf->caller, name, name_size, ino, d_type);
         kfree(name);
         if (!rc)
                 buf->entries_written++;
-out:
+
         return rc;
 }
 
diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 847904aa63a9..97d17eaeba07 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -395,8 +395,7 @@ static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode,
 
         mount_crypt_stat = &ecryptfs_superblock_to_private(
                                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
-        if (mount_crypt_stat
-            && (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
+        if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
                 rc = ecryptfs_encrypt_and_encode_filename(
                         &encrypted_and_encoded_name, &len,
                         mount_crypt_stat, name, len);
diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c
index c89a58cfc991..e74fe84d0886 100644
--- a/fs/ecryptfs/keystore.c
+++ b/fs/ecryptfs/keystore.c
@@ -1880,7 +1880,7 @@ find_next_matching_auth_tok:
                 candidate_auth_tok = &auth_tok_list_item->auth_tok;
                 if (unlikely(ecryptfs_verbosity > 0)) {
                         ecryptfs_printk(KERN_DEBUG,
-                                        "Considering cadidate auth tok:\n");
+                                        "Considering candidate auth tok:\n");
                         ecryptfs_dump_auth_tok(candidate_auth_tok);
                 }
                 rc = ecryptfs_get_auth_tok_sig(&candidate_auth_tok_sig,