@@ -155,6 +155,16 @@ struct fscrypt_context {
__u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
} __attribute__((packed));
+/**
+ * For encrypted symlinks, the ciphertext length is stored at the beginning
+ * of the string in little-endian format.
+ */
+struct fscrypt_symlink_data {
+ __le16 len;
+ char encrypted_path[1];
+} __attribute__((packed));
+
+
#ifndef FS_MAX_KEY_SIZE
#define FS_MAX_KEY_SIZE 64
#endif
@@ -578,15 +588,22 @@ static struct fscrypt_context *init_fscrypt_context(void)
new_fctx->format = FS_ENCRYPTION_CONTEXT_FORMAT_V1;
new_fctx->contents_encryption_mode = FS_ENCRYPTION_MODE_AES_128_CBC;
new_fctx->filenames_encryption_mode = FS_ENCRYPTION_MODE_AES_128_CTS;
- //TODO accept padding via a parameter
new_fctx->flags = FS_POLICY_FLAGS_PAD_4;
- //TODO accept descriptor via a parameter
- RAND_bytes((void *)&new_fctx->master_key_descriptor, FS_KEY_DESCRIPTOR_SIZE);
RAND_bytes((void *)&new_fctx->nonce, FS_KEY_DERIVATION_NONCE_SIZE);
return new_fctx;
}
+unsigned int fscrypt_fname_encrypted_size(struct fscrypt_context *fctx, unsigned int ilen)
+{
+ int padding;
+
+ padding = 4 << (fctx->flags & FS_POLICY_FLAGS_PAD_MASK);
+ ilen = max_t(unsigned int, ilen, FS_CRYPTO_BLOCK_SIZE);
+ return round_up(ilen, padding);
+}
+
+
/**
* open_ubi - open the UBI volume.
* @node: name of the UBI volume character device to fetch information about
@@ -1478,11 +1495,54 @@ static int add_inode(struct stat *st, ino_t inum, void *data,
ino->gid = cpu_to_le32(st->st_gid);
ino->mode = cpu_to_le32(st->st_mode);
ino->flags = cpu_to_le32(use_flags);
- ino->data_len = cpu_to_le32(data_len);
ino->compr_type = cpu_to_le16(c->default_compr);
- if (data_len)
- memcpy(&ino->data, data, data_len);
+ if (data_len) {
+ if (!S_ISLNK(st->st_mode))
+ return err_msg("Expected symlink");
+ if (!fctx) {
+ memcpy(&ino->data, data, data_len);
+ } else {
+ //TODO turn this into a common helper
+ struct fscrypt_symlink_data *sd;
+ void *inbuf, *outbuf, *crypt_key;
+ unsigned int max_namelen = UBIFS_MAX_INO_DATA;
+ unsigned int padding = 4 << (fctx->flags & FS_POLICY_FLAGS_PAD_MASK);
+ unsigned int cryptlen;
+ unsigned int link_disk_len = fscrypt_fname_encrypted_size(fctx, data_len) + sizeof(struct fscrypt_symlink_data);
+
+ cryptlen = max_t(unsigned int, data_len, FS_CRYPTO_BLOCK_SIZE);
+ cryptlen = round_up(cryptlen, padding);
+ cryptlen = min(cryptlen, max_namelen);
+
+ sd = xzalloc(link_disk_len);
+ inbuf = xmalloc(cryptlen);
+ /* CTS mode needs a block size aligned buffer */
+ outbuf = xmalloc(round_up(cryptlen, FS_CRYPTO_BLOCK_SIZE));
+
+ memset(inbuf, 0, cryptlen);
+ memcpy(inbuf, data, data_len);
+
+ crypt_key = calc_fscrypt_subkey(fctx);
+ if (!crypt_key)
+ return err_msg("could not compute subkey");
+ if (encrypt_aes128_cbc_cts(inbuf, cryptlen, crypt_key, outbuf) < 0)
+ return err_msg("could not encrypt filename");
+
+ memcpy(sd->encrypted_path, outbuf, cryptlen);
+ sd->len = cpu_to_le16(cryptlen);
+ memcpy(&ino->data, sd, link_disk_len);
+ ((char *)&ino->data)[link_disk_len - 1] = '\0';
+
+ data_len = link_disk_len;
+
+ free(crypt_key);
+ free(inbuf);
+ free(outbuf);
+ free(sd);
+ }
+ }
+ ino->data_len = cpu_to_le32(data_len);
len = UBIFS_INO_NODE_SZ + data_len;
if (xattr_path) {
@@ -1635,7 +1695,8 @@ static int add_dent_node(ino_t dir_inum, const char *name, ino_t inum,
cryptlen = min(cryptlen, max_namelen);
inbuf = xmalloc(cryptlen);
- outbuf = xmalloc(cryptlen + 32);
+ /* CTS mode needs a block size aligned buffer */
+ outbuf = xmalloc(round_up(cryptlen, FS_CRYPTO_BLOCK_SIZE));
memset(inbuf, 0, cryptlen);
memcpy(inbuf, dname.name, dname.len);
Signed-off-by: Richard Weinberger <richard@nod.at> --- ubifs-utils/mkfs.ubifs/mkfs.ubifs.c | 75 ++++++++++++++++++++++++++--- 1 file changed, 68 insertions(+), 7 deletions(-)