diff options
Diffstat (limited to 'fs/f2fs/crypto_fname.c')
| -rw-r--r-- | fs/f2fs/crypto_fname.c | 440 |
1 files changed, 440 insertions, 0 deletions
diff --git a/fs/f2fs/crypto_fname.c b/fs/f2fs/crypto_fname.c new file mode 100644 index 000000000000..ab377d496a39 --- /dev/null +++ b/fs/f2fs/crypto_fname.c @@ -0,0 +1,440 @@ +/* + * 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; +} |