diff options
Diffstat (limited to 'fs/crypto')
| -rw-r--r-- | fs/crypto/crypto.c | 1 | ||||
| -rw-r--r-- | fs/crypto/fname.c | 140 | ||||
| -rw-r--r-- | fs/crypto/fscrypt_private.h | 31 | ||||
| -rw-r--r-- | fs/crypto/hooks.c | 158 | ||||
| -rw-r--r-- | fs/crypto/keyinfo.c | 17 |
5 files changed, 255 insertions, 92 deletions
diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c index 732a786cce9d..ce654526c0fb 100644 --- a/fs/crypto/crypto.c +++ b/fs/crypto/crypto.c @@ -27,6 +27,7 @@ #include <linux/dcache.h> #include <linux/namei.h> #include <crypto/aes.h> +#include <crypto/skcipher.h> #include "fscrypt_private.h" static unsigned int num_prealloc_crypto_pages = 32; diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c index 305541bcd108..e33f3d3c5ade 100644 --- a/fs/crypto/fname.c +++ b/fs/crypto/fname.c @@ -13,42 +13,46 @@ #include <linux/scatterlist.h> #include <linux/ratelimit.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 caller must have allocated sufficient memory for the @oname string. + * 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 */ -static int fname_encrypt(struct inode *inode, - const struct qstr *iname, struct fscrypt_str *oname) +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; + struct crypto_skcipher *tfm = inode->i_crypt_info->ci_ctfm; int res = 0; char iv[FS_CRYPTO_BLOCK_SIZE]; struct scatterlist sg; - int padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK); - unsigned int lim; - unsigned int cryptlen; - - lim = inode->i_sb->s_cop->max_namelen(inode); - if (iname->len <= 0 || iname->len > lim) - return -EIO; /* * Copy the filename to the output buffer for encrypting in-place and * pad it with the needed number of NUL bytes. */ - cryptlen = max_t(unsigned int, iname->len, FS_CRYPTO_BLOCK_SIZE); - cryptlen = round_up(cryptlen, padding); - cryptlen = min(cryptlen, lim); - memcpy(oname->name, iname->name, iname->len); - memset(oname->name + iname->len, 0, cryptlen - iname->len); + 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 */ memset(iv, 0, FS_CRYPTO_BLOCK_SIZE); @@ -63,8 +67,8 @@ static int fname_encrypt(struct inode *inode, skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, crypto_req_done, &wait); - sg_init_one(&sg, oname->name, cryptlen); - skcipher_request_set_crypt(req, &sg, &sg, cryptlen, iv); + 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); @@ -75,7 +79,6 @@ static int fname_encrypt(struct inode *inode, return res; } - oname->len = cryptlen; return 0; } @@ -188,50 +191,52 @@ static int digest_decode(const char *src, int len, char *dst) return cp - dst; } -u32 fscrypt_fname_encrypted_size(const struct inode *inode, u32 ilen) +bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len, + u32 max_len, u32 *encrypted_len_ret) { - int padding = 32; - struct fscrypt_info *ci = inode->i_crypt_info; - - if (ci) - padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK); - ilen = max(ilen, (u32)FS_CRYPTO_BLOCK_SIZE); - return round_up(ilen, padding); + 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; } -EXPORT_SYMBOL(fscrypt_fname_encrypted_size); /** - * fscrypt_fname_crypto_alloc_obuff() - + * 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. * - * Allocates an output buffer that is sufficient for the crypto operation - * specified by the context and the direction. + * Return: 0 on success, -errno on failure */ int fscrypt_fname_alloc_buffer(const struct inode *inode, - u32 ilen, struct fscrypt_str *crypto_str) + u32 max_encrypted_len, + struct fscrypt_str *crypto_str) { - u32 olen = fscrypt_fname_encrypted_size(inode, ilen); 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; - crypto_str->len = olen; - olen = max(olen, max_encoded_len); + max_presented_len = max(max_encoded_len, max_encrypted_len); - /* - * Allocated buffer can hold one more character to null-terminate the - * string - */ - crypto_str->name = kmalloc(olen + 1, GFP_NOFS); - if (!(crypto_str->name)) + 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_crypto_free_buffer() - + * fscrypt_fname_free_buffer - free the buffer for presented filenames * - * Frees the buffer allocated for crypto operation. + * Free the buffer allocated by fscrypt_fname_alloc_buffer(). */ void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str) { @@ -298,35 +303,6 @@ int fscrypt_fname_disk_to_usr(struct inode *inode, EXPORT_SYMBOL(fscrypt_fname_disk_to_usr); /** - * fscrypt_fname_usr_to_disk() - converts a filename from user space to disk - * space - * - * The caller must have allocated sufficient memory for the @oname string. - * - * Return: 0 on success, -errno on failure - */ -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 0; - } - 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 -ENOKEY; -} -EXPORT_SYMBOL(fscrypt_fname_usr_to_disk); - -/** * 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 @@ -369,11 +345,17 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, return ret; if (dir->i_crypt_info) { - ret = fscrypt_fname_alloc_buffer(dir, iname->len, - &fname->crypto_buf); - if (ret) - return ret; - ret = fname_encrypt(dir, iname, &fname->crypto_buf); + if (!fscrypt_fname_encrypted_size(dir, iname->len, + dir->i_sb->s_cop->max_namelen(dir), + &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; @@ -425,7 +407,7 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, return 0; errout: - fscrypt_fname_free_buffer(&fname->crypto_buf); + kfree(fname->crypto_buf.name); return ret; } EXPORT_SYMBOL(fscrypt_setup_filename); diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h index c0b4f5597e1a..ad6722bae8b7 100644 --- a/fs/crypto/fscrypt_private.h +++ b/fs/crypto/fscrypt_private.h @@ -50,6 +50,15 @@ struct fscrypt_context { #define FS_ENCRYPTION_CONTEXT_FORMAT_V1 1 +/** + * For encrypted symlinks, the ciphertext length is stored at the beginning + * of the string in little-endian format. + */ +struct fscrypt_symlink_data { + __le16 len; + char encrypted_path[1]; +} __packed; + /* * A pointer to this structure is stored in the file system's in-core * representation of an inode. @@ -71,7 +80,22 @@ typedef enum { #define FS_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001 #define FS_CTX_HAS_BOUNCE_BUFFER_FL 0x00000002 +static inline bool fscrypt_valid_enc_modes(u32 contents_mode, + u32 filenames_mode) +{ + if (contents_mode == FS_ENCRYPTION_MODE_AES_128_CBC && + filenames_mode == FS_ENCRYPTION_MODE_AES_128_CTS) + return true; + + if (contents_mode == FS_ENCRYPTION_MODE_AES_256_XTS && + filenames_mode == FS_ENCRYPTION_MODE_AES_256_CTS) + return true; + + return false; +} + /* crypto.c */ +extern struct kmem_cache *fscrypt_info_cachep; extern int fscrypt_initialize(unsigned int cop_flags); extern struct workqueue_struct *fscrypt_read_workqueue; extern int fscrypt_do_page_crypto(const struct inode *inode, @@ -83,6 +107,13 @@ extern int fscrypt_do_page_crypto(const struct inode *inode, extern struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx, gfp_t gfp_flags); +/* fname.c */ +extern int fname_encrypt(struct inode *inode, const struct qstr *iname, + u8 *out, unsigned int olen); +extern bool fscrypt_fname_encrypted_size(const struct inode *inode, + u32 orig_len, u32 max_len, + u32 *encrypted_len_ret); + /* keyinfo.c */ extern void __exit fscrypt_essiv_cleanup(void); diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c index 9f5fb2eb9cf7..bec06490fb13 100644 --- a/fs/crypto/hooks.c +++ b/fs/crypto/hooks.c @@ -110,3 +110,161 @@ int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry) return 0; } EXPORT_SYMBOL_GPL(__fscrypt_prepare_lookup); + +int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len, + unsigned int max_len, + struct fscrypt_str *disk_link) +{ + int err; + + /* + * To calculate the size of the encrypted symlink target we need to know + * the amount of NUL padding, which is determined by the flags set in + * the encryption policy which will be inherited from the directory. + * The easiest way to get access to this is to just load the directory's + * fscrypt_info, since we'll need it to create the dir_entry anyway. + * + * Note: in test_dummy_encryption mode, @dir may be unencrypted. + */ + err = fscrypt_get_encryption_info(dir); + if (err) + return err; + if (!fscrypt_has_encryption_key(dir)) + return -ENOKEY; + + /* + * Calculate the size of the encrypted symlink and verify it won't + * exceed max_len. Note that for historical reasons, encrypted symlink + * targets are prefixed with the ciphertext length, despite this + * actually being redundant with i_size. This decreases by 2 bytes the + * longest symlink target we can accept. + * + * We could recover 1 byte by not counting a null terminator, but + * counting it (even though it is meaningless for ciphertext) is simpler + * for now since filesystems will assume it is there and subtract it. + */ + if (!fscrypt_fname_encrypted_size(dir, len, + max_len - sizeof(struct fscrypt_symlink_data), + &disk_link->len)) + return -ENAMETOOLONG; + disk_link->len += sizeof(struct fscrypt_symlink_data); + + disk_link->name = NULL; + return 0; +} +EXPORT_SYMBOL_GPL(__fscrypt_prepare_symlink); + +int __fscrypt_encrypt_symlink(struct inode *inode, const char *target, + unsigned int len, struct fscrypt_str *disk_link) +{ + int err; + struct qstr iname = QSTR_INIT(target, len); + struct fscrypt_symlink_data *sd; + unsigned int ciphertext_len; + + err = fscrypt_require_key(inode); + if (err) + return err; + + if (disk_link->name) { + /* filesystem-provided buffer */ + sd = (struct fscrypt_symlink_data *)disk_link->name; + } else { + sd = kmalloc(disk_link->len, GFP_NOFS); + if (!sd) + return -ENOMEM; + } + ciphertext_len = disk_link->len - sizeof(*sd); + sd->len = cpu_to_le16(ciphertext_len); + + err = fname_encrypt(inode, &iname, sd->encrypted_path, ciphertext_len); + if (err) { + if (!disk_link->name) + kfree(sd); + return err; + } + /* + * Null-terminating the ciphertext doesn't make sense, but we still + * count the null terminator in the length, so we might as well + * initialize it just in case the filesystem writes it out. + */ + sd->encrypted_path[ciphertext_len] = '\0'; + + if (!disk_link->name) + disk_link->name = (unsigned char *)sd; + return 0; +} +EXPORT_SYMBOL_GPL(__fscrypt_encrypt_symlink); + +/** + * fscrypt_get_symlink - get the target of an encrypted symlink + * @inode: the symlink inode + * @caddr: the on-disk contents of the symlink + * @max_size: size of @caddr buffer + * @done: if successful, will be set up to free the returned target + * + * If the symlink's encryption key is available, we decrypt its target. + * Otherwise, we encode its target for presentation. + * + * This may sleep, so the filesystem must have dropped out of RCU mode already. + * + * Return: the presentable symlink target or an ERR_PTR() + */ +const char *fscrypt_get_symlink(struct inode *inode, const void *caddr, + unsigned int max_size, + struct delayed_call *done) +{ + const struct fscrypt_symlink_data *sd; + struct fscrypt_str cstr, pstr; + int err; + + /* This is for encrypted symlinks only */ + if (WARN_ON(!IS_ENCRYPTED(inode))) + return ERR_PTR(-EINVAL); + + /* + * Try to set up the symlink's encryption key, but we can continue + * regardless of whether the key is available or not. + */ + err = fscrypt_get_encryption_info(inode); + if (err) + return ERR_PTR(err); + + /* + * For historical reasons, encrypted symlink targets are prefixed with + * the ciphertext length, even though this is redundant with i_size. + */ + + if (max_size < sizeof(*sd)) + return ERR_PTR(-EUCLEAN); + sd = caddr; + cstr.name = (unsigned char *)sd->encrypted_path; + cstr.len = le16_to_cpu(sd->len); + + if (cstr.len == 0) + return ERR_PTR(-EUCLEAN); + + if (cstr.len + sizeof(*sd) - 1 > max_size) + return ERR_PTR(-EUCLEAN); + + err = fscrypt_fname_alloc_buffer(inode, cstr.len, &pstr); + if (err) + return ERR_PTR(err); + + err = fscrypt_fname_disk_to_usr(inode, 0, 0, &cstr, &pstr); + if (err) + goto err_kfree; + + err = -EUCLEAN; + if (pstr.name[0] == '\0') + goto err_kfree; + + pstr.name[pstr.len] = '\0'; + set_delayed_call(done, kfree_link, pstr.name); + return pstr.name; + +err_kfree: + kfree(pstr.name); + return ERR_PTR(err); +} +EXPORT_SYMBOL_GPL(fscrypt_get_symlink); diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c index 5e6e846f5a24..05f5ee1f0705 100644 --- a/fs/crypto/keyinfo.c +++ b/fs/crypto/keyinfo.c @@ -14,6 +14,7 @@ #include <linux/ratelimit.h> #include <crypto/aes.h> #include <crypto/sha.h> +#include <crypto/skcipher.h> #include "fscrypt_private.h" static struct crypto_shash *essiv_hash_tfm; @@ -354,19 +355,9 @@ out: } EXPORT_SYMBOL(fscrypt_get_encryption_info); -void fscrypt_put_encryption_info(struct inode *inode, struct fscrypt_info *ci) +void fscrypt_put_encryption_info(struct inode *inode) { - struct fscrypt_info *prev; - - if (ci == NULL) - ci = READ_ONCE(inode->i_crypt_info); - if (ci == NULL) - return; - - prev = cmpxchg(&inode->i_crypt_info, ci, NULL); - if (prev != ci) - return; - - put_crypt_info(ci); + put_crypt_info(inode->i_crypt_info); + inode->i_crypt_info = NULL; } EXPORT_SYMBOL(fscrypt_put_encryption_info); |