Merge tag 'v3.3-rc4' into for-3.4 in order to resolve the conflict

[firefly-linux-kernel-4.4.55.git] / fs / ecryptfs / crypto.c

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 63ab24510649cc3a3604e9dd603904d9676a2794..ea9931281557ad8d3ed4049b48c66110df5f0811 100644 (file)
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -1990,6 +1990,17 @@ out:
        return;
 }
 
+static size_t ecryptfs_max_decoded_size(size_t encoded_size)
+{
+       /* Not exact; conservatively long. Every block of 4
+        * encoded characters decodes into a block of 3
+        * decoded characters. This segment of code provides
+        * the caller with the maximum amount of allocated
+        * space that @dst will need to point to in a
+        * subsequent call. */
+       return ((encoded_size + 1) * 3) / 4;
+}
+
 /**
  * ecryptfs_decode_from_filename
  * @dst: If NULL, this function only sets @dst_size and returns. If
@@ -2008,13 +2019,7 @@ ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
        size_t dst_byte_offset = 0;
 
        if (dst == NULL) {
-               /* Not exact; conservatively long. Every block of 4
-                * encoded characters decodes into a block of 3
-                * decoded characters. This segment of code provides
-                * the caller with the maximum amount of allocated
-                * space that @dst will need to point to in a
-                * subsequent call. */
-               (*dst_size) = (((src_size + 1) * 3) / 4);
+               (*dst_size) = ecryptfs_max_decoded_size(src_size);
                goto out;
        }
        while (src_byte_offset < src_size) {
@@ -2239,3 +2244,52 @@ out_free:
 out:
        return rc;
 }
+
+#define ENC_NAME_MAX_BLOCKLEN_8_OR_16  143
+
+int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
+                          struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
+{
+       struct blkcipher_desc desc;
+       struct mutex *tfm_mutex;
+       size_t cipher_blocksize;
+       int rc;
+
+       if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
+               (*namelen) = lower_namelen;
+               return 0;
+       }
+
+       rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
+                       mount_crypt_stat->global_default_fn_cipher_name);
+       if (unlikely(rc)) {
+               (*namelen) = 0;
+               return rc;
+       }
+
+       mutex_lock(tfm_mutex);
+       cipher_blocksize = crypto_blkcipher_blocksize(desc.tfm);
+       mutex_unlock(tfm_mutex);
+
+       /* Return an exact amount for the common cases */
+       if (lower_namelen == NAME_MAX
+           && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
+               (*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
+               return 0;
+       }
+
+       /* Return a safe estimate for the uncommon cases */
+       (*namelen) = lower_namelen;
+       (*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
+       /* Since this is the max decoded size, subtract 1 "decoded block" len */
+       (*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
+       (*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
+       (*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
+       /* Worst case is that the filename is padded nearly a full block size */
+       (*namelen) -= cipher_blocksize - 1;
+
+       if ((*namelen) < 0)
+               (*namelen) = 0;
+
+       return 0;
+}