| /* |
| * linux/fs/f2fs/crypto_fname.c |
| * |
| * Copied from linux/fs/ext4/crypto.c |
| * |
| * Copyright (C) 2015, Google, Inc. |
| * Copyright (C) 2015, Motorola Mobility |
| * |
| * This contains functions for filename crypto management in f2fs |
| * |
| * Written by Uday Savagaonkar, 2014. |
| * |
| * Adjust f2fs dentry structure |
| * Jaegeuk Kim, 2015. |
| * |
| * This has not yet undergone a rigorous security audit. |
| */ |
| #include <crypto/hash.h> |
| #include <crypto/sha.h> |
| #include <keys/encrypted-type.h> |
| #include <keys/user-type.h> |
| #include <linux/crypto.h> |
| #include <linux/gfp.h> |
| #include <linux/kernel.h> |
| #include <linux/key.h> |
| #include <linux/list.h> |
| #include <linux/mempool.h> |
| #include <linux/random.h> |
| #include <linux/scatterlist.h> |
| #include <linux/spinlock_types.h> |
| #include <linux/f2fs_fs.h> |
| #include <linux/ratelimit.h> |
| |
| #include "f2fs.h" |
| #include "f2fs_crypto.h" |
| #include "xattr.h" |
| |
| /** |
| * f2fs_dir_crypt_complete() - |
| */ |
| static void f2fs_dir_crypt_complete(struct crypto_async_request *req, int res) |
| { |
| struct f2fs_completion_result *ecr = req->data; |
| |
| if (res == -EINPROGRESS) |
| return; |
| ecr->res = res; |
| complete(&ecr->completion); |
| } |
| |
| bool f2fs_valid_filenames_enc_mode(uint32_t mode) |
| { |
| return (mode == F2FS_ENCRYPTION_MODE_AES_256_CTS); |
| } |
| |
| static unsigned max_name_len(struct inode *inode) |
| { |
| return S_ISLNK(inode->i_mode) ? inode->i_sb->s_blocksize : |
| F2FS_NAME_LEN; |
| } |
| |
| /** |
| * f2fs_fname_encrypt() - |
| * |
| * This function encrypts the input filename, and returns the length of the |
| * ciphertext. Errors are returned as negative numbers. We trust the caller to |
| * allocate sufficient memory to oname string. |
| */ |
| static int f2fs_fname_encrypt(struct inode *inode, |
| const struct qstr *iname, struct f2fs_str *oname) |
| { |
| u32 ciphertext_len; |
| struct ablkcipher_request *req = NULL; |
| DECLARE_F2FS_COMPLETION_RESULT(ecr); |
| struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info; |
| struct crypto_ablkcipher *tfm = ci->ci_ctfm; |
| int res = 0; |
| char iv[F2FS_CRYPTO_BLOCK_SIZE]; |
| struct scatterlist src_sg, dst_sg; |
| int padding = 4 << (ci->ci_flags & F2FS_POLICY_FLAGS_PAD_MASK); |
| char *workbuf, buf[32], *alloc_buf = NULL; |
| unsigned lim = max_name_len(inode); |
| |
| if (iname->len <= 0 || iname->len > lim) |
| return -EIO; |
| |
| ciphertext_len = (iname->len < F2FS_CRYPTO_BLOCK_SIZE) ? |
| F2FS_CRYPTO_BLOCK_SIZE : iname->len; |
| ciphertext_len = f2fs_fname_crypto_round_up(ciphertext_len, padding); |
| ciphertext_len = (ciphertext_len > lim) ? lim : ciphertext_len; |
| |
| if (ciphertext_len <= sizeof(buf)) { |
| workbuf = buf; |
| } else { |
| alloc_buf = kmalloc(ciphertext_len, GFP_NOFS); |
| if (!alloc_buf) |
| return -ENOMEM; |
| workbuf = alloc_buf; |
| } |
| |
| /* Allocate request */ |
| req = ablkcipher_request_alloc(tfm, GFP_NOFS); |
| if (!req) { |
| printk_ratelimited(KERN_ERR |
| "%s: crypto_request_alloc() failed\n", __func__); |
| kfree(alloc_buf); |
| return -ENOMEM; |
| } |
| ablkcipher_request_set_callback(req, |
| CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, |
| f2fs_dir_crypt_complete, &ecr); |
| |
| /* Copy the input */ |
| memcpy(workbuf, iname->name, iname->len); |
| if (iname->len < ciphertext_len) |
| memset(workbuf + iname->len, 0, ciphertext_len - iname->len); |
| |
| /* Initialize IV */ |
| memset(iv, 0, F2FS_CRYPTO_BLOCK_SIZE); |
| |
| /* Create encryption request */ |
| sg_init_one(&src_sg, workbuf, ciphertext_len); |
| sg_init_one(&dst_sg, oname->name, ciphertext_len); |
| ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, ciphertext_len, iv); |
| res = crypto_ablkcipher_encrypt(req); |
| if (res == -EINPROGRESS || res == -EBUSY) { |
| BUG_ON(req->base.data != &ecr); |
| wait_for_completion(&ecr.completion); |
| res = ecr.res; |
| } |
| kfree(alloc_buf); |
| ablkcipher_request_free(req); |
| if (res < 0) { |
| printk_ratelimited(KERN_ERR |
| "%s: Error (error code %d)\n", __func__, res); |
| } |
| oname->len = ciphertext_len; |
| return res; |
| } |
| |
| /* |
| * f2fs_fname_decrypt() |
| * This function decrypts the input filename, and returns |
| * the length of the plaintext. |
| * Errors are returned as negative numbers. |
| * We trust the caller to allocate sufficient memory to oname string. |
| */ |
| static int f2fs_fname_decrypt(struct inode *inode, |
| const struct f2fs_str *iname, struct f2fs_str *oname) |
| { |
| struct ablkcipher_request *req = NULL; |
| DECLARE_F2FS_COMPLETION_RESULT(ecr); |
| struct scatterlist src_sg, dst_sg; |
| struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info; |
| struct crypto_ablkcipher *tfm = ci->ci_ctfm; |
| int res = 0; |
| char iv[F2FS_CRYPTO_BLOCK_SIZE]; |
| unsigned lim = max_name_len(inode); |
| |
| if (iname->len <= 0 || iname->len > lim) |
| return -EIO; |
| |
| /* Allocate request */ |
| req = ablkcipher_request_alloc(tfm, GFP_NOFS); |
| if (!req) { |
| printk_ratelimited(KERN_ERR |
| "%s: crypto_request_alloc() failed\n", __func__); |
| return -ENOMEM; |
| } |
| ablkcipher_request_set_callback(req, |
| CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, |
| f2fs_dir_crypt_complete, &ecr); |
| |
| /* Initialize IV */ |
| memset(iv, 0, F2FS_CRYPTO_BLOCK_SIZE); |
| |
| /* Create decryption request */ |
| sg_init_one(&src_sg, iname->name, iname->len); |
| sg_init_one(&dst_sg, oname->name, oname->len); |
| ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, iv); |
| res = crypto_ablkcipher_decrypt(req); |
| if (res == -EINPROGRESS || res == -EBUSY) { |
| BUG_ON(req->base.data != &ecr); |
| wait_for_completion(&ecr.completion); |
| res = ecr.res; |
| } |
| ablkcipher_request_free(req); |
| if (res < 0) { |
| printk_ratelimited(KERN_ERR |
| "%s: Error in f2fs_fname_decrypt (error code %d)\n", |
| __func__, res); |
| return res; |
| } |
| |
| oname->len = strnlen(oname->name, iname->len); |
| return oname->len; |
| } |
| |
| static const char *lookup_table = |
| "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,"; |
| |
| /** |
| * f2fs_fname_encode_digest() - |
| * |
| * 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; |
| } |
| |
| /** |
| * f2fs_fname_crypto_round_up() - |
| * |
| * Return: The next multiple of block size |
| */ |
| u32 f2fs_fname_crypto_round_up(u32 size, u32 blksize) |
| { |
| return ((size + blksize - 1) / blksize) * blksize; |
| } |
| |
| /** |
| * f2fs_fname_crypto_alloc_obuff() - |
| * |
| * Allocates an output buffer that is sufficient for the crypto operation |
| * specified by the context and the direction. |
| */ |
| int f2fs_fname_crypto_alloc_buffer(struct inode *inode, |
| u32 ilen, struct f2fs_str *crypto_str) |
| { |
| unsigned int olen; |
| int padding = 16; |
| struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info; |
| |
| if (ci) |
| padding = 4 << (ci->ci_flags & F2FS_POLICY_FLAGS_PAD_MASK); |
| if (padding < F2FS_CRYPTO_BLOCK_SIZE) |
| padding = F2FS_CRYPTO_BLOCK_SIZE; |
| olen = f2fs_fname_crypto_round_up(ilen, padding); |
| crypto_str->len = olen; |
| if (olen < F2FS_FNAME_CRYPTO_DIGEST_SIZE * 2) |
| olen = F2FS_FNAME_CRYPTO_DIGEST_SIZE * 2; |
| /* Allocated buffer can hold one more character to null-terminate the |
| * string */ |
| crypto_str->name = kmalloc(olen + 1, GFP_NOFS); |
| if (!(crypto_str->name)) |
| return -ENOMEM; |
| return 0; |
| } |
| |
| /** |
| * f2fs_fname_crypto_free_buffer() - |
| * |
| * Frees the buffer allocated for crypto operation. |
| */ |
| void f2fs_fname_crypto_free_buffer(struct f2fs_str *crypto_str) |
| { |
| if (!crypto_str) |
| return; |
| kfree(crypto_str->name); |
| crypto_str->name = NULL; |
| } |
| |
| /** |
| * f2fs_fname_disk_to_usr() - converts a filename from disk space to user space |
| */ |
| int f2fs_fname_disk_to_usr(struct inode *inode, |
| f2fs_hash_t *hash, |
| const struct f2fs_str *iname, |
| struct f2fs_str *oname) |
| { |
| const struct qstr qname = FSTR_TO_QSTR(iname); |
| char buf[24]; |
| int ret; |
| |
| if (is_dot_dotdot(&qname)) { |
| oname->name[0] = '.'; |
| oname->name[iname->len - 1] = '.'; |
| oname->len = iname->len; |
| return oname->len; |
| } |
| |
| if (F2FS_I(inode)->i_crypt_info) |
| return f2fs_fname_decrypt(inode, iname, oname); |
| |
| if (iname->len <= F2FS_FNAME_CRYPTO_DIGEST_SIZE) { |
| ret = digest_encode(iname->name, iname->len, oname->name); |
| oname->len = ret; |
| return ret; |
| } |
| if (hash) { |
| memcpy(buf, hash, 4); |
| memset(buf + 4, 0, 4); |
| } else |
| memset(buf, 0, 8); |
| memcpy(buf + 8, iname->name + iname->len - 16, 16); |
| oname->name[0] = '_'; |
| ret = digest_encode(buf, 24, oname->name + 1); |
| oname->len = ret + 1; |
| return ret + 1; |
| } |
| |
| /** |
| * f2fs_fname_usr_to_disk() - converts a filename from user space to disk space |
| */ |
| int f2fs_fname_usr_to_disk(struct inode *inode, |
| const struct qstr *iname, |
| struct f2fs_str *oname) |
| { |
| int res; |
| struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info; |
| |
| if (is_dot_dotdot(iname)) { |
| oname->name[0] = '.'; |
| oname->name[iname->len - 1] = '.'; |
| oname->len = iname->len; |
| return oname->len; |
| } |
| |
| if (ci) { |
| res = f2fs_fname_encrypt(inode, iname, oname); |
| return res; |
| } |
| /* Without a proper key, a user is not allowed to modify the filenames |
| * in a directory. Consequently, a user space name cannot be mapped to |
| * a disk-space name */ |
| return -EACCES; |
| } |
| |
| int f2fs_fname_setup_filename(struct inode *dir, const struct qstr *iname, |
| int lookup, struct f2fs_filename *fname) |
| { |
| struct f2fs_crypt_info *ci; |
| int ret = 0, bigname = 0; |
| |
| memset(fname, 0, sizeof(struct f2fs_filename)); |
| fname->usr_fname = iname; |
| |
| if (!f2fs_encrypted_inode(dir) || is_dot_dotdot(iname)) { |
| fname->disk_name.name = (unsigned char *)iname->name; |
| fname->disk_name.len = iname->len; |
| return 0; |
| } |
| ret = f2fs_get_encryption_info(dir); |
| if (ret) |
| return ret; |
| ci = F2FS_I(dir)->i_crypt_info; |
| if (ci) { |
| ret = f2fs_fname_crypto_alloc_buffer(dir, iname->len, |
| &fname->crypto_buf); |
| if (ret < 0) |
| return ret; |
| ret = f2fs_fname_encrypt(dir, iname, &fname->crypto_buf); |
| if (ret < 0) |
| goto errout; |
| fname->disk_name.name = fname->crypto_buf.name; |
| fname->disk_name.len = fname->crypto_buf.len; |
| return 0; |
| } |
| if (!lookup) |
| return -EACCES; |
| |
| /* 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; |
| |
| fname->crypto_buf.name = kmalloc(32, GFP_KERNEL); |
| if (fname->crypto_buf.name == NULL) |
| return -ENOMEM; |
| ret = digest_decode(iname->name + bigname, iname->len - bigname, |
| 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); |
| } else { |
| fname->disk_name.name = fname->crypto_buf.name; |
| fname->disk_name.len = fname->crypto_buf.len; |
| } |
| return 0; |
| errout: |
| f2fs_fname_crypto_free_buffer(&fname->crypto_buf); |
| return ret; |
| } |
| |
| void f2fs_fname_free_filename(struct f2fs_filename *fname) |
| { |
| kfree(fname->crypto_buf.name); |
| fname->crypto_buf.name = NULL; |
| fname->usr_fname = NULL; |
| fname->disk_name.name = NULL; |
| } |