diff options
author | Jaegeuk Kim <jaegeuk@kernel.org> | 2015-05-16 01:26:10 +0200 |
---|---|---|
committer | Jaegeuk Kim <jaegeuk@kernel.org> | 2016-03-18 05:19:33 +0100 |
commit | 0b81d0779072696371822e5ed9e7c6292e547024 (patch) | |
tree | c75412a642ee596fd33a392f0f353c4c1185f7f5 /fs/crypto/fname.c | |
parent | f2fs: mutex can't be used by down_write_nest_lock() (diff) | |
download | linux-0b81d0779072696371822e5ed9e7c6292e547024.tar.xz linux-0b81d0779072696371822e5ed9e7c6292e547024.zip |
fs crypto: move per-file encryption from f2fs tree to fs/crypto
This patch adds the renamed functions moved from the f2fs crypto files.
1. definitions for per-file encryption used by ext4 and f2fs.
2. crypto.c for encrypt/decrypt functions
a. IO preparation:
- fscrypt_get_ctx / fscrypt_release_ctx
b. before IOs:
- fscrypt_encrypt_page
- fscrypt_decrypt_page
- fscrypt_zeroout_range
c. after IOs:
- fscrypt_decrypt_bio_pages
- fscrypt_pullback_bio_page
- fscrypt_restore_control_page
3. policy.c supporting context management.
a. For ioctls:
- fscrypt_process_policy
- fscrypt_get_policy
b. For context permission
- fscrypt_has_permitted_context
- fscrypt_inherit_context
4. keyinfo.c to handle permissions
- fscrypt_get_encryption_info
- fscrypt_free_encryption_info
5. fname.c to support filename encryption
a. general wrapper functions
- fscrypt_fname_disk_to_usr
- fscrypt_fname_usr_to_disk
- fscrypt_setup_filename
- fscrypt_free_filename
b. specific filename handling functions
- fscrypt_fname_alloc_buffer
- fscrypt_fname_free_buffer
6. Makefile and Kconfig
Cc: Al Viro <viro@ftp.linux.org.uk>
Signed-off-by: Michael Halcrow <mhalcrow@google.com>
Signed-off-by: Ildar Muslukhov <ildarm@google.com>
Signed-off-by: Uday Savagaonkar <savagaon@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Diffstat (limited to 'fs/crypto/fname.c')
-rw-r--r-- | fs/crypto/fname.c | 427 |
1 files changed, 427 insertions, 0 deletions
diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c new file mode 100644 index 000000000000..5e4ddeeba267 --- /dev/null +++ b/fs/crypto/fname.c @@ -0,0 +1,427 @@ +/* + * 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 <crypto/hash.h> +#include <crypto/sha.h> +#include <keys/encrypted-type.h> +#include <keys/user-type.h> +#include <linux/crypto.h> +#include <linux/scatterlist.h> +#include <linux/ratelimit.h> +#include <linux/fscrypto.h> + +static u32 size_round_up(size_t size, size_t blksize) +{ + return ((size + blksize - 1) / blksize) * blksize; +} + +/** + * dir_crypt_complete() - + */ +static void dir_crypt_complete(struct crypto_async_request *req, int res) +{ + struct fscrypt_completion_result *ecr = req->data; + + if (res == -EINPROGRESS) + return; + ecr->res = res; + complete(&ecr->completion); +} + +/** + * 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 fname_encrypt(struct inode *inode, + const struct qstr *iname, struct fscrypt_str *oname) +{ + u32 ciphertext_len; + struct ablkcipher_request *req = NULL; + DECLARE_FS_COMPLETION_RESULT(ecr); + struct fscrypt_info *ci = inode->i_crypt_info; + struct crypto_ablkcipher *tfm = ci->ci_ctfm; + int res = 0; + char iv[FS_CRYPTO_BLOCK_SIZE]; + struct scatterlist src_sg, dst_sg; + int padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK); + char *workbuf, buf[32], *alloc_buf = NULL; + unsigned lim; + + lim = inode->i_sb->s_cop->max_namelen(inode); + if (iname->len <= 0 || iname->len > lim) + return -EIO; + + ciphertext_len = (iname->len < FS_CRYPTO_BLOCK_SIZE) ? + FS_CRYPTO_BLOCK_SIZE : iname->len; + ciphertext_len = size_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, + 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, FS_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) { + 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; +} + +/* + * 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 fname_decrypt(struct inode *inode, + const struct fscrypt_str *iname, + struct fscrypt_str *oname) +{ + struct ablkcipher_request *req = NULL; + DECLARE_FS_COMPLETION_RESULT(ecr); + struct scatterlist src_sg, dst_sg; + struct fscrypt_info *ci = inode->i_crypt_info; + struct crypto_ablkcipher *tfm = ci->ci_ctfm; + int res = 0; + char iv[FS_CRYPTO_BLOCK_SIZE]; + unsigned lim; + + lim = inode->i_sb->s_cop->max_namelen(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, + dir_crypt_complete, &ecr); + + /* Initialize IV */ + memset(iv, 0, FS_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) { + wait_for_completion(&ecr.completion); + res = ecr.res; + } + ablkcipher_request_free(req); + if (res < 0) { + printk_ratelimited(KERN_ERR + "%s: Error (error code %d)\n", __func__, res); + return res; + } + + oname->len = strnlen(oname->name, iname->len); + return oname->len; +} + +static const char *lookup_table = + "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,"; + +/** + * 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; +} + +u32 fscrypt_fname_encrypted_size(struct inode *inode, u32 ilen) +{ + int padding = 32; + struct fscrypt_info *ci = inode->i_crypt_info; + + if (ci) + padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK); + if (ilen < FS_CRYPTO_BLOCK_SIZE) + ilen = FS_CRYPTO_BLOCK_SIZE; + return size_round_up(ilen, padding); +} +EXPORT_SYMBOL(fscrypt_fname_encrypted_size); + +/** + * fscrypt_fname_crypto_alloc_obuff() - + * + * Allocates an output buffer that is sufficient for the crypto operation + * specified by the context and the direction. + */ +int fscrypt_fname_alloc_buffer(struct inode *inode, + u32 ilen, struct fscrypt_str *crypto_str) +{ + unsigned int olen = fscrypt_fname_encrypted_size(inode, ilen); + + crypto_str->len = olen; + if (olen < FS_FNAME_CRYPTO_DIGEST_SIZE * 2) + olen = FS_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; +} +EXPORT_SYMBOL(fscrypt_fname_alloc_buffer); + +/** + * fscrypt_fname_crypto_free_buffer() - + * + * Frees the buffer allocated for crypto operation. + */ +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 + */ +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); + char buf[24]; + int ret; + + if (fscrypt_is_dot_dotdot(&qname)) { + oname->name[0] = '.'; + oname->name[iname->len - 1] = '.'; + oname->len = iname->len; + return oname->len; + } + + if (iname->len < FS_CRYPTO_BLOCK_SIZE) + return -EUCLEAN; + + if (inode->i_crypt_info) + return fname_decrypt(inode, iname, oname); + + if (iname->len <= FS_FNAME_CRYPTO_DIGEST_SIZE) { + ret = digest_encode(iname->name, iname->len, oname->name); + oname->len = ret; + return ret; + } + if (hash) { + memcpy(buf, &hash, 4); + memcpy(buf + 4, &minor_hash, 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; +} +EXPORT_SYMBOL(fscrypt_fname_disk_to_usr); + +/** + * fscrypt_fname_usr_to_disk() - converts a filename from user space to disk + * space + */ +int fscrypt_fname_usr_to_disk(struct inode *inode, + const struct qstr *iname, + struct fscrypt_str *oname) +{ + if (fscrypt_is_dot_dotdot(iname)) { + oname->name[0] = '.'; + oname->name[iname->len - 1] = '.'; + oname->len = iname->len; + return oname->len; + } + if (inode->i_crypt_info) + return fname_encrypt(inode, iname, oname); + /* + * 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; +} +EXPORT_SYMBOL(fscrypt_fname_usr_to_disk); + +int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, + int lookup, struct fscrypt_name *fname) +{ + int ret = 0, bigname = 0; + + memset(fname, 0, sizeof(struct fscrypt_name)); + fname->usr_fname = iname; + + if (!dir->i_sb->s_cop->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 = get_crypt_info(dir); + if (ret && ret != -EOPNOTSUPP) + return ret; + + if (dir->i_crypt_info) { + ret = fscrypt_fname_alloc_buffer(dir, iname->len, + &fname->crypto_buf); + if (ret < 0) + return ret; + ret = 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); + memcpy(&fname->minor_hash, fname->crypto_buf.name + 4, 4); + } else { + fname->disk_name.name = fname->crypto_buf.name; + fname->disk_name.len = fname->crypto_buf.len; + } + return 0; + +errout: + fscrypt_fname_free_buffer(&fname->crypto_buf); + return ret; +} +EXPORT_SYMBOL(fscrypt_setup_filename); + +void fscrypt_free_filename(struct fscrypt_name *fname) +{ + kfree(fname->crypto_buf.name); + fname->crypto_buf.name = NULL; + fname->usr_fname = NULL; + fname->disk_name.name = NULL; +} +EXPORT_SYMBOL(fscrypt_free_filename); |