static const char *lookup_table =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
+#define BASE64_CHARS(nbytes) DIV_ROUND_UP((nbytes) * 4, 3)
+
/**
* digest_encode() -
*
int fscrypt_fname_alloc_buffer(const struct inode *inode,
u32 ilen, struct fscrypt_str *crypto_str)
{
- unsigned int olen = fscrypt_fname_encrypted_size(inode, ilen);
+ u32 olen = fscrypt_fname_encrypted_size(inode, ilen);
+ const u32 max_encoded_len =
+ max_t(u32, BASE64_CHARS(FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE),
+ 1 + BASE64_CHARS(sizeof(struct fscrypt_digested_name)));
crypto_str->len = olen;
- if (olen < FS_FNAME_CRYPTO_DIGEST_SIZE * 2)
- olen = FS_FNAME_CRYPTO_DIGEST_SIZE * 2;
+ olen = max(olen, max_encoded_len);
+
/*
* Allocated buffer can hold one more character to null-terminate the
* string
*
* The caller must have allocated sufficient memory for the @oname string.
*
+ * If the key is available, we'll decrypt the disk name; otherwise, we'll encode
+ * it for presentation. Short names are directly base64-encoded, while long
+ * names are encoded in fscrypt_digested_name format.
+ *
* Return: 0 on success, -errno on failure
*/
int fscrypt_fname_disk_to_usr(struct inode *inode,
struct fscrypt_str *oname)
{
const struct qstr qname = FSTR_TO_QSTR(iname);
- char buf[24];
+ struct fscrypt_digested_name digested_name;
if (fscrypt_is_dot_dotdot(&qname)) {
oname->name[0] = '.';
if (inode->i_crypt_info)
return fname_decrypt(inode, iname, oname);
- if (iname->len <= FS_FNAME_CRYPTO_DIGEST_SIZE) {
+ if (iname->len <= FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE) {
oname->len = digest_encode(iname->name, iname->len,
oname->name);
return 0;
}
if (hash) {
- memcpy(buf, &hash, 4);
- memcpy(buf + 4, &minor_hash, 4);
+ digested_name.hash = hash;
+ digested_name.minor_hash = minor_hash;
} else {
- memset(buf, 0, 8);
+ digested_name.hash = 0;
+ digested_name.minor_hash = 0;
}
- memcpy(buf + 8, iname->name + iname->len - 16, 16);
+ memcpy(digested_name.digest,
+ FSCRYPT_FNAME_DIGEST(iname->name, iname->len),
+ FSCRYPT_FNAME_DIGEST_SIZE);
oname->name[0] = '_';
- oname->len = 1 + digest_encode(buf, 24, oname->name + 1);
+ oname->len = 1 + digest_encode((const char *)&digested_name,
+ sizeof(digested_name), oname->name + 1);
return 0;
}
EXPORT_SYMBOL(fscrypt_fname_disk_to_usr);
}
EXPORT_SYMBOL(fscrypt_fname_usr_to_disk);
+/**
+ * fscrypt_setup_filename() - prepare to search a possibly encrypted directory
+ * @dir: the directory that will be searched
+ * @iname: the user-provided filename being searched for
+ * @lookup: 1 if we're allowed to proceed without the key because it's
+ * ->lookup() or we're finding the dir_entry for deletion; 0 if we cannot
+ * proceed without the key because we're going to create the dir_entry.
+ * @fname: the filename information to be filled in
+ *
+ * Given a user-provided filename @iname, this function sets @fname->disk_name
+ * to the name that would be stored in the on-disk directory entry, if possible.
+ * If the directory is unencrypted this is simply @iname. Else, if we have the
+ * directory's encryption key, then @iname is the plaintext, so we encrypt it to
+ * get the disk_name.
+ *
+ * Else, for keyless @lookup operations, @iname is the presented ciphertext, so
+ * we decode it to get either the ciphertext disk_name (for short names) or the
+ * fscrypt_digested_name (for long names). Non-@lookup operations will be
+ * impossible in this case, so we fail them with ENOKEY.
+ *
+ * If successful, fscrypt_free_filename() must be called later to clean up.
+ *
+ * Return: 0 on success, -errno on failure
+ */
int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname,
int lookup, struct fscrypt_name *fname)
{
- int ret = 0, bigname = 0;
+ int ret;
+ int digested;
memset(fname, 0, sizeof(struct fscrypt_name));
fname->usr_fname = iname;
* We don't have the key and we are doing a lookup; decode the
* user-supplied name
*/
- if (iname->name[0] == '_')
- bigname = 1;
- if ((bigname && (iname->len != 33)) || (!bigname && (iname->len > 43)))
- return -ENOENT;
+ if (iname->name[0] == '_') {
+ if (iname->len !=
+ 1 + BASE64_CHARS(sizeof(struct fscrypt_digested_name)))
+ return -ENOENT;
+ digested = 1;
+ } else {
+ if (iname->len >
+ BASE64_CHARS(FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE))
+ return -ENOENT;
+ digested = 0;
+ }
- fname->crypto_buf.name = kmalloc(32, GFP_KERNEL);
+ fname->crypto_buf.name =
+ kmalloc(max_t(size_t, FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE,
+ sizeof(struct fscrypt_digested_name)),
+ GFP_KERNEL);
if (fname->crypto_buf.name == NULL)
return -ENOMEM;
- ret = digest_decode(iname->name + bigname, iname->len - bigname,
+ ret = digest_decode(iname->name + digested, iname->len - digested,
fname->crypto_buf.name);
if (ret < 0) {
ret = -ENOENT;
goto errout;
}
fname->crypto_buf.len = ret;
- if (bigname) {
- memcpy(&fname->hash, fname->crypto_buf.name, 4);
- memcpy(&fname->minor_hash, fname->crypto_buf.name + 4, 4);
+ if (digested) {
+ const struct fscrypt_digested_name *n =
+ (const void *)fname->crypto_buf.name;
+ fname->hash = n->hash;
+ fname->minor_hash = n->minor_hash;
} else {
fname->disk_name.name = fname->crypto_buf.name;
fname->disk_name.len = fname->crypto_buf.len;
projects / linux-block.git / blobdiff