mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-31 00:17:44 +00:00
0bb06cac06
These should have been removed during commit 544d08fde2
("fscrypt: use
a common logging function"), but I missed them.
Signed-off-by: Eric Biggers <ebiggers@google.com>
405 lines
11 KiB
C
405 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* This contains functions for filename crypto management
|
|
*
|
|
* Copyright (C) 2015, Google, Inc.
|
|
* Copyright (C) 2015, Motorola Mobility
|
|
*
|
|
* Written by Uday Savagaonkar, 2014.
|
|
* Modified by Jaegeuk Kim, 2015.
|
|
*
|
|
* This has not yet undergone a rigorous security audit.
|
|
*/
|
|
|
|
#include <linux/scatterlist.h>
|
|
#include <crypto/skcipher.h>
|
|
#include "fscrypt_private.h"
|
|
|
|
static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
|
|
{
|
|
if (str->len == 1 && str->name[0] == '.')
|
|
return true;
|
|
|
|
if (str->len == 2 && str->name[0] == '.' && str->name[1] == '.')
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* fname_encrypt() - encrypt a filename
|
|
*
|
|
* The output buffer must be at least as large as the input buffer.
|
|
* Any extra space is filled with NUL padding before encryption.
|
|
*
|
|
* Return: 0 on success, -errno on failure
|
|
*/
|
|
int fname_encrypt(struct inode *inode, const struct qstr *iname,
|
|
u8 *out, unsigned int olen)
|
|
{
|
|
struct skcipher_request *req = NULL;
|
|
DECLARE_CRYPTO_WAIT(wait);
|
|
struct fscrypt_info *ci = inode->i_crypt_info;
|
|
struct crypto_skcipher *tfm = ci->ci_ctfm;
|
|
union fscrypt_iv iv;
|
|
struct scatterlist sg;
|
|
int res;
|
|
|
|
/*
|
|
* Copy the filename to the output buffer for encrypting in-place and
|
|
* pad it with the needed number of NUL bytes.
|
|
*/
|
|
if (WARN_ON(olen < iname->len))
|
|
return -ENOBUFS;
|
|
memcpy(out, iname->name, iname->len);
|
|
memset(out + iname->len, 0, olen - iname->len);
|
|
|
|
/* Initialize the IV */
|
|
fscrypt_generate_iv(&iv, 0, ci);
|
|
|
|
/* Set up the encryption request */
|
|
req = skcipher_request_alloc(tfm, GFP_NOFS);
|
|
if (!req)
|
|
return -ENOMEM;
|
|
skcipher_request_set_callback(req,
|
|
CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
|
|
crypto_req_done, &wait);
|
|
sg_init_one(&sg, out, olen);
|
|
skcipher_request_set_crypt(req, &sg, &sg, olen, &iv);
|
|
|
|
/* Do the encryption */
|
|
res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
|
|
skcipher_request_free(req);
|
|
if (res < 0) {
|
|
fscrypt_err(inode->i_sb,
|
|
"Filename encryption failed for inode %lu: %d",
|
|
inode->i_ino, res);
|
|
return res;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* fname_decrypt() - decrypt a filename
|
|
*
|
|
* The caller must have allocated sufficient memory for the @oname string.
|
|
*
|
|
* Return: 0 on success, -errno on failure
|
|
*/
|
|
static int fname_decrypt(struct inode *inode,
|
|
const struct fscrypt_str *iname,
|
|
struct fscrypt_str *oname)
|
|
{
|
|
struct skcipher_request *req = NULL;
|
|
DECLARE_CRYPTO_WAIT(wait);
|
|
struct scatterlist src_sg, dst_sg;
|
|
struct fscrypt_info *ci = inode->i_crypt_info;
|
|
struct crypto_skcipher *tfm = ci->ci_ctfm;
|
|
union fscrypt_iv iv;
|
|
int res;
|
|
|
|
/* Allocate request */
|
|
req = skcipher_request_alloc(tfm, GFP_NOFS);
|
|
if (!req)
|
|
return -ENOMEM;
|
|
skcipher_request_set_callback(req,
|
|
CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
|
|
crypto_req_done, &wait);
|
|
|
|
/* Initialize IV */
|
|
fscrypt_generate_iv(&iv, 0, ci);
|
|
|
|
/* Create decryption request */
|
|
sg_init_one(&src_sg, iname->name, iname->len);
|
|
sg_init_one(&dst_sg, oname->name, oname->len);
|
|
skcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, &iv);
|
|
res = crypto_wait_req(crypto_skcipher_decrypt(req), &wait);
|
|
skcipher_request_free(req);
|
|
if (res < 0) {
|
|
fscrypt_err(inode->i_sb,
|
|
"Filename decryption failed for inode %lu: %d",
|
|
inode->i_ino, res);
|
|
return res;
|
|
}
|
|
|
|
oname->len = strnlen(oname->name, iname->len);
|
|
return 0;
|
|
}
|
|
|
|
static const char *lookup_table =
|
|
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
|
|
|
|
#define BASE64_CHARS(nbytes) DIV_ROUND_UP((nbytes) * 4, 3)
|
|
|
|
/**
|
|
* digest_encode() -
|
|
*
|
|
* Encodes the input digest using characters from the set [a-zA-Z0-9_+].
|
|
* The encoded string is roughly 4/3 times the size of the input string.
|
|
*/
|
|
static int digest_encode(const char *src, int len, char *dst)
|
|
{
|
|
int i = 0, bits = 0, ac = 0;
|
|
char *cp = dst;
|
|
|
|
while (i < len) {
|
|
ac += (((unsigned char) src[i]) << bits);
|
|
bits += 8;
|
|
do {
|
|
*cp++ = lookup_table[ac & 0x3f];
|
|
ac >>= 6;
|
|
bits -= 6;
|
|
} while (bits >= 6);
|
|
i++;
|
|
}
|
|
if (bits)
|
|
*cp++ = lookup_table[ac & 0x3f];
|
|
return cp - dst;
|
|
}
|
|
|
|
static int digest_decode(const char *src, int len, char *dst)
|
|
{
|
|
int i = 0, bits = 0, ac = 0;
|
|
const char *p;
|
|
char *cp = dst;
|
|
|
|
while (i < len) {
|
|
p = strchr(lookup_table, src[i]);
|
|
if (p == NULL || src[i] == 0)
|
|
return -2;
|
|
ac += (p - lookup_table) << bits;
|
|
bits += 6;
|
|
if (bits >= 8) {
|
|
*cp++ = ac & 0xff;
|
|
ac >>= 8;
|
|
bits -= 8;
|
|
}
|
|
i++;
|
|
}
|
|
if (ac)
|
|
return -1;
|
|
return cp - dst;
|
|
}
|
|
|
|
bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len,
|
|
u32 max_len, u32 *encrypted_len_ret)
|
|
{
|
|
int padding = 4 << (inode->i_crypt_info->ci_flags &
|
|
FS_POLICY_FLAGS_PAD_MASK);
|
|
u32 encrypted_len;
|
|
|
|
if (orig_len > max_len)
|
|
return false;
|
|
encrypted_len = max(orig_len, (u32)FS_CRYPTO_BLOCK_SIZE);
|
|
encrypted_len = round_up(encrypted_len, padding);
|
|
*encrypted_len_ret = min(encrypted_len, max_len);
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* fscrypt_fname_alloc_buffer - allocate a buffer for presented filenames
|
|
*
|
|
* Allocate a buffer that is large enough to hold any decrypted or encoded
|
|
* filename (null-terminated), for the given maximum encrypted filename length.
|
|
*
|
|
* Return: 0 on success, -errno on failure
|
|
*/
|
|
int fscrypt_fname_alloc_buffer(const struct inode *inode,
|
|
u32 max_encrypted_len,
|
|
struct fscrypt_str *crypto_str)
|
|
{
|
|
const u32 max_encoded_len =
|
|
max_t(u32, BASE64_CHARS(FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE),
|
|
1 + BASE64_CHARS(sizeof(struct fscrypt_digested_name)));
|
|
u32 max_presented_len;
|
|
|
|
max_presented_len = max(max_encoded_len, max_encrypted_len);
|
|
|
|
crypto_str->name = kmalloc(max_presented_len + 1, GFP_NOFS);
|
|
if (!crypto_str->name)
|
|
return -ENOMEM;
|
|
crypto_str->len = max_presented_len;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(fscrypt_fname_alloc_buffer);
|
|
|
|
/**
|
|
* fscrypt_fname_free_buffer - free the buffer for presented filenames
|
|
*
|
|
* Free the buffer allocated by fscrypt_fname_alloc_buffer().
|
|
*/
|
|
void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str)
|
|
{
|
|
if (!crypto_str)
|
|
return;
|
|
kfree(crypto_str->name);
|
|
crypto_str->name = NULL;
|
|
}
|
|
EXPORT_SYMBOL(fscrypt_fname_free_buffer);
|
|
|
|
/**
|
|
* fscrypt_fname_disk_to_usr() - converts a filename from disk space to user
|
|
* space
|
|
*
|
|
* 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,
|
|
u32 hash, u32 minor_hash,
|
|
const struct fscrypt_str *iname,
|
|
struct fscrypt_str *oname)
|
|
{
|
|
const struct qstr qname = FSTR_TO_QSTR(iname);
|
|
struct fscrypt_digested_name digested_name;
|
|
|
|
if (fscrypt_is_dot_dotdot(&qname)) {
|
|
oname->name[0] = '.';
|
|
oname->name[iname->len - 1] = '.';
|
|
oname->len = iname->len;
|
|
return 0;
|
|
}
|
|
|
|
if (iname->len < FS_CRYPTO_BLOCK_SIZE)
|
|
return -EUCLEAN;
|
|
|
|
if (fscrypt_has_encryption_key(inode))
|
|
return fname_decrypt(inode, iname, oname);
|
|
|
|
if (iname->len <= FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE) {
|
|
oname->len = digest_encode(iname->name, iname->len,
|
|
oname->name);
|
|
return 0;
|
|
}
|
|
if (hash) {
|
|
digested_name.hash = hash;
|
|
digested_name.minor_hash = minor_hash;
|
|
} else {
|
|
digested_name.hash = 0;
|
|
digested_name.minor_hash = 0;
|
|
}
|
|
memcpy(digested_name.digest,
|
|
FSCRYPT_FNAME_DIGEST(iname->name, iname->len),
|
|
FSCRYPT_FNAME_DIGEST_SIZE);
|
|
oname->name[0] = '_';
|
|
oname->len = 1 + digest_encode((const char *)&digested_name,
|
|
sizeof(digested_name), oname->name + 1);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(fscrypt_fname_disk_to_usr);
|
|
|
|
/**
|
|
* 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;
|
|
int digested;
|
|
|
|
memset(fname, 0, sizeof(struct fscrypt_name));
|
|
fname->usr_fname = iname;
|
|
|
|
if (!IS_ENCRYPTED(dir) || fscrypt_is_dot_dotdot(iname)) {
|
|
fname->disk_name.name = (unsigned char *)iname->name;
|
|
fname->disk_name.len = iname->len;
|
|
return 0;
|
|
}
|
|
ret = fscrypt_get_encryption_info(dir);
|
|
if (ret)
|
|
return ret;
|
|
|
|
if (fscrypt_has_encryption_key(dir)) {
|
|
if (!fscrypt_fname_encrypted_size(dir, iname->len,
|
|
dir->i_sb->s_cop->max_namelen,
|
|
&fname->crypto_buf.len))
|
|
return -ENAMETOOLONG;
|
|
fname->crypto_buf.name = kmalloc(fname->crypto_buf.len,
|
|
GFP_NOFS);
|
|
if (!fname->crypto_buf.name)
|
|
return -ENOMEM;
|
|
|
|
ret = fname_encrypt(dir, iname, fname->crypto_buf.name,
|
|
fname->crypto_buf.len);
|
|
if (ret)
|
|
goto errout;
|
|
fname->disk_name.name = fname->crypto_buf.name;
|
|
fname->disk_name.len = fname->crypto_buf.len;
|
|
return 0;
|
|
}
|
|
if (!lookup)
|
|
return -ENOKEY;
|
|
fname->is_ciphertext_name = true;
|
|
|
|
/*
|
|
* We don't have the key and we are doing a lookup; decode the
|
|
* user-supplied name
|
|
*/
|
|
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(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 + digested, iname->len - digested,
|
|
fname->crypto_buf.name);
|
|
if (ret < 0) {
|
|
ret = -ENOENT;
|
|
goto errout;
|
|
}
|
|
fname->crypto_buf.len = ret;
|
|
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;
|
|
}
|
|
return 0;
|
|
|
|
errout:
|
|
kfree(fname->crypto_buf.name);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(fscrypt_setup_filename);
|