diff options
Diffstat (limited to 'fs/ecryptfs/crypto.c')
| -rw-r--r-- | fs/ecryptfs/crypto.c | 433 |
1 files changed, 433 insertions, 0 deletions
diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c index c9839df37c7d..18c78abba683 100644 --- a/fs/ecryptfs/crypto.c +++ b/fs/ecryptfs/crypto.c @@ -1721,6 +1721,98 @@ out: } /** + * ecryptfs_encrypt_filename - encrypt filename + * + * CBC-encrypts the filename. We do not want to encrypt the same + * filename with the same key and IV, which may happen with hard + * links, so we prepend random bits to each filename. + * + * Returns zero on success; non-zero otherwise + */ +static int +ecryptfs_encrypt_filename(struct ecryptfs_filename *filename, + struct ecryptfs_crypt_stat *crypt_stat, + struct ecryptfs_mount_crypt_stat *mount_crypt_stat) +{ + int rc = 0; + + filename->encrypted_filename = NULL; + filename->encrypted_filename_size = 0; + if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCFN_USE_MOUNT_FNEK)) + || (mount_crypt_stat && (mount_crypt_stat->flags + & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) { + size_t packet_size; + size_t remaining_bytes; + + rc = ecryptfs_write_tag_70_packet( + NULL, NULL, + &filename->encrypted_filename_size, + mount_crypt_stat, NULL, + filename->filename_size); + if (rc) { + printk(KERN_ERR "%s: Error attempting to get packet " + "size for tag 72; rc = [%d]\n", __func__, + rc); + filename->encrypted_filename_size = 0; + goto out; + } + filename->encrypted_filename = + kmalloc(filename->encrypted_filename_size, GFP_KERNEL); + if (!filename->encrypted_filename) { + printk(KERN_ERR "%s: Out of memory whilst attempting " + "to kmalloc [%Zd] bytes\n", __func__, + filename->encrypted_filename_size); + rc = -ENOMEM; + goto out; + } + remaining_bytes = filename->encrypted_filename_size; + rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename, + &remaining_bytes, + &packet_size, + mount_crypt_stat, + filename->filename, + filename->filename_size); + if (rc) { + printk(KERN_ERR "%s: Error attempting to generate " + "tag 70 packet; rc = [%d]\n", __func__, + rc); + kfree(filename->encrypted_filename); + filename->encrypted_filename = NULL; + filename->encrypted_filename_size = 0; + goto out; + } + filename->encrypted_filename_size = packet_size; + } else { + printk(KERN_ERR "%s: No support for requested filename " + "encryption method in this release\n", __func__); + rc = -ENOTSUPP; + goto out; + } +out: + return rc; +} + +static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size, + const char *name, size_t name_size) +{ + int rc = 0; + + (*copied_name) = kmalloc((name_size + 2), GFP_KERNEL); + if (!(*copied_name)) { + rc = -ENOMEM; + goto out; + } + memcpy((void *)(*copied_name), (void *)name, name_size); + (*copied_name)[(name_size)] = '\0'; /* Only for convenience + * in printing out the + * string in debug + * messages */ + (*copied_name_size) = (name_size + 1); +out: + return rc; +} + +/** * ecryptfs_process_key_cipher - Perform key cipher initialization. * @key_tfm: Crypto context for key material, set by this function * @cipher_name: Name of the cipher @@ -1911,3 +2003,344 @@ out: mutex_unlock(&key_tfm_list_mutex); return rc; } + +/* 64 characters forming a 6-bit target field */ +static unsigned char *portable_filename_chars = ("-.0123456789ABCD" + "EFGHIJKLMNOPQRST" + "UVWXYZabcdefghij" + "klmnopqrstuvwxyz"); + +/* We could either offset on every reverse map or just pad some 0x00's + * at the front here */ +static unsigned char filename_rev_map[] = { + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */ + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */ + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */ + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */ + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */ + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */ + 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */ + 0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */ + 0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */ + 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */ + 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */ + 0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */ + 0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */ + 0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */ + 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */ + 0x3D, 0x3E, 0x3F +}; + +/** + * ecryptfs_encode_for_filename + * @dst: Destination location for encoded filename + * @dst_size: Size of the encoded filename in bytes + * @src: Source location for the filename to encode + * @src_size: Size of the source in bytes + */ +void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size, + unsigned char *src, size_t src_size) +{ + size_t num_blocks; + size_t block_num = 0; + size_t dst_offset = 0; + unsigned char last_block[3]; + + if (src_size == 0) { + (*dst_size) = 0; + goto out; + } + num_blocks = (src_size / 3); + if ((src_size % 3) == 0) { + memcpy(last_block, (&src[src_size - 3]), 3); + } else { + num_blocks++; + last_block[2] = 0x00; + switch (src_size % 3) { + case 1: + last_block[0] = src[src_size - 1]; + last_block[1] = 0x00; + break; + case 2: + last_block[0] = src[src_size - 2]; + last_block[1] = src[src_size - 1]; + } + } + (*dst_size) = (num_blocks * 4); + if (!dst) + goto out; + while (block_num < num_blocks) { + unsigned char *src_block; + unsigned char dst_block[4]; + + if (block_num == (num_blocks - 1)) + src_block = last_block; + else + src_block = &src[block_num * 3]; + dst_block[0] = ((src_block[0] >> 2) & 0x3F); + dst_block[1] = (((src_block[0] << 4) & 0x30) + | ((src_block[1] >> 4) & 0x0F)); + dst_block[2] = (((src_block[1] << 2) & 0x3C) + | ((src_block[2] >> 6) & 0x03)); + dst_block[3] = (src_block[2] & 0x3F); + dst[dst_offset++] = portable_filename_chars[dst_block[0]]; + dst[dst_offset++] = portable_filename_chars[dst_block[1]]; + dst[dst_offset++] = portable_filename_chars[dst_block[2]]; + dst[dst_offset++] = portable_filename_chars[dst_block[3]]; + block_num++; + } +out: + return; +} + +int ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size, + const unsigned char *src, size_t src_size) +{ + u8 current_bit_offset = 0; + size_t src_byte_offset = 0; + size_t dst_byte_offset = 0; + int rc = 0; + + if (dst == NULL) { + /* Not exact; conservatively long */ + (*dst_size) = (((src_size + 1) * 3) / 4); + goto out; + } + while (src_byte_offset < src_size) { + unsigned char src_byte = + filename_rev_map[(int)src[src_byte_offset]]; + + switch (current_bit_offset) { + case 0: + dst[dst_byte_offset] = (src_byte << 2); + current_bit_offset = 6; + break; + case 6: + dst[dst_byte_offset++] |= (src_byte >> 4); + dst[dst_byte_offset] = ((src_byte & 0xF) + << 4); + current_bit_offset = 4; + break; + case 4: + dst[dst_byte_offset++] |= (src_byte >> 2); + dst[dst_byte_offset] = (src_byte << 6); + current_bit_offset = 2; + break; + case 2: + dst[dst_byte_offset++] |= (src_byte); + dst[dst_byte_offset] = 0; + current_bit_offset = 0; + break; + } + src_byte_offset++; + } + (*dst_size) = dst_byte_offset; +out: + return rc; +} + +/** + * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text + * @crypt_stat: The crypt_stat struct associated with the file anem to encode + * @name: The plaintext name + * @length: The length of the plaintext + * @encoded_name: The encypted name + * + * Encrypts and encodes a filename into something that constitutes a + * valid filename for a filesystem, with printable characters. + * + * We assume that we have a properly initialized crypto context, + * pointed to by crypt_stat->tfm. + * + * Returns zero on success; non-zero on otherwise + */ +int ecryptfs_encrypt_and_encode_filename( + char **encoded_name, + size_t *encoded_name_size, + struct ecryptfs_crypt_stat *crypt_stat, + struct ecryptfs_mount_crypt_stat *mount_crypt_stat, + const char *name, size_t name_size) +{ + size_t encoded_name_no_prefix_size; + int rc = 0; + + (*encoded_name) = NULL; + (*encoded_name_size) = 0; + if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCRYPT_FILENAMES)) + || (mount_crypt_stat && (mount_crypt_stat->flags + & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES))) { + struct ecryptfs_filename *filename; + + filename = kzalloc(sizeof(*filename), GFP_KERNEL); + if (!filename) { + printk(KERN_ERR "%s: Out of memory whilst attempting " + "to kzalloc [%d] bytes\n", __func__, + sizeof(*filename)); + rc = -ENOMEM; + goto out; + } + filename->filename = (char *)name; + filename->filename_size = name_size; + rc = ecryptfs_encrypt_filename(filename, crypt_stat, + mount_crypt_stat); + if (rc) { + printk(KERN_ERR "%s: Error attempting to encrypt " + "filename; rc = [%d]\n", __func__, rc); + kfree(filename); + goto out; + } + ecryptfs_encode_for_filename( + NULL, &encoded_name_no_prefix_size, + filename->encrypted_filename, + filename->encrypted_filename_size); + if ((crypt_stat && (crypt_stat->flags + & ECRYPTFS_ENCFN_USE_MOUNT_FNEK)) + || (mount_crypt_stat + && (mount_crypt_stat->flags + & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) + (*encoded_name_size) = + (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE + + encoded_name_no_prefix_size); + else + (*encoded_name_size) = + (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE + + encoded_name_no_prefix_size); + (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL); + if (!(*encoded_name)) { + printk(KERN_ERR "%s: Out of memory whilst attempting " + "to kzalloc [%d] bytes\n", __func__, + (*encoded_name_size)); + rc = -ENOMEM; + kfree(filename->encrypted_filename); + kfree(filename); + goto out; + } + if ((crypt_stat && (crypt_stat->flags + & ECRYPTFS_ENCFN_USE_MOUNT_FNEK)) + || (mount_crypt_stat + && (mount_crypt_stat->flags + & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) { + memcpy((*encoded_name), + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX, + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE); + ecryptfs_encode_for_filename( + ((*encoded_name) + + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE), + &encoded_name_no_prefix_size, + filename->encrypted_filename, + filename->encrypted_filename_size); + (*encoded_name_size) = + (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE + + encoded_name_no_prefix_size); + (*encoded_name)[(*encoded_name_size)] = '\0'; + (*encoded_name_size)++; + } else { + rc = -ENOTSUPP; + } + if (rc) { + printk(KERN_ERR "%s: Error attempting to encode " + "encrypted filename; rc = [%d]\n", __func__, + rc); + kfree((*encoded_name)); + (*encoded_name) = NULL; + (*encoded_name_size) = 0; + } + kfree(filename->encrypted_filename); + kfree(filename); + } else { + rc = ecryptfs_copy_filename(encoded_name, + encoded_name_size, + name, name_size); + } +out: + return rc; +} + +/** + * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext + * @plaintext_name: The plaintext name + * @plaintext_name_size: The plaintext name size + * @ecryptfs_dir_dentry: eCryptfs directory dentry + * @name: The filename in cipher text + * @name_size: The cipher text name size + * + * Decrypts and decodes the filename. + * + * Returns zero on error; non-zero otherwise + */ +int ecryptfs_decode_and_decrypt_filename(char **plaintext_name, + size_t *plaintext_name_size, + struct dentry *ecryptfs_dir_dentry, + const char *name, size_t name_size) +{ + char *decoded_name; + size_t decoded_name_size; + size_t packet_size; + int rc = 0; + + if ((name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) + && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX, + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) { + struct ecryptfs_mount_crypt_stat *mount_crypt_stat = + &ecryptfs_superblock_to_private( + ecryptfs_dir_dentry->d_sb)->mount_crypt_stat; + const char *orig_name = name; + size_t orig_name_size = name_size; + + name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE; + name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE; + rc = ecryptfs_decode_from_filename(NULL, &decoded_name_size, + name, name_size); + if (rc) { + printk(KERN_ERR "%s: Error attempting to decode " + "filename; rc = [%d]\n", __func__, rc); + rc = ecryptfs_copy_filename(plaintext_name, + plaintext_name_size, + orig_name, orig_name_size); + goto out; + } + decoded_name = kmalloc(decoded_name_size, GFP_KERNEL); + if (!decoded_name) { + printk(KERN_ERR "%s: Out of memory whilst attempting " + "to kmalloc [%Zd] bytes\n", __func__, + decoded_name_size); + rc = -ENOMEM; + goto out; + } + rc = ecryptfs_decode_from_filename(decoded_name, + &decoded_name_size, + name, name_size); + if (rc) { + printk(KERN_ERR "%s: Error attempting to decode " + "filename; rc = [%d]\n", __func__, rc); + rc = ecryptfs_copy_filename(plaintext_name, + plaintext_name_size, + orig_name, orig_name_size); + goto out_free; + } + rc = ecryptfs_parse_tag_70_packet(plaintext_name, + plaintext_name_size, + &packet_size, + mount_crypt_stat, + 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); + goto out_free; + } + } else { + rc = ecryptfs_copy_filename(plaintext_name, + plaintext_name_size, + name, name_size); + goto out; + } +out_free: + kfree(decoded_name); +out: + return rc; +} |