diff options
Diffstat (limited to 'fs/crypto')
| -rw-r--r-- | fs/crypto/Kconfig | 22 | ||||
| -rw-r--r-- | fs/crypto/bio.c | 114 | ||||
| -rw-r--r-- | fs/crypto/crypto.c | 57 | ||||
| -rw-r--r-- | fs/crypto/fname.c | 316 | ||||
| -rw-r--r-- | fs/crypto/fscrypt_private.h | 58 | ||||
| -rw-r--r-- | fs/crypto/hkdf.c | 2 | ||||
| -rw-r--r-- | fs/crypto/hooks.c | 47 | ||||
| -rw-r--r-- | fs/crypto/keyring.c | 149 | ||||
| -rw-r--r-- | fs/crypto/keysetup.c | 102 | ||||
| -rw-r--r-- | fs/crypto/keysetup_v1.c | 19 | ||||
| -rw-r--r-- | fs/crypto/policy.c | 170 |
11 files changed, 727 insertions, 329 deletions
diff --git a/fs/crypto/Kconfig b/fs/crypto/Kconfig index ff5a1746cbae..8046d7c7a3e9 100644 --- a/fs/crypto/Kconfig +++ b/fs/crypto/Kconfig @@ -2,13 +2,8 @@ config FS_ENCRYPTION bool "FS Encryption (Per-file encryption)" select CRYPTO - select CRYPTO_AES - select CRYPTO_CBC - select CRYPTO_ECB - select CRYPTO_XTS - select CRYPTO_CTS - select CRYPTO_SHA512 - select CRYPTO_HMAC + select CRYPTO_HASH + select CRYPTO_SKCIPHER select KEYS help Enable encryption of files and directories. This @@ -16,3 +11,16 @@ config FS_ENCRYPTION efficient since it avoids caching the encrypted and decrypted pages in the page cache. Currently Ext4, F2FS and UBIFS make use of this feature. + +# Filesystems supporting encryption must select this if FS_ENCRYPTION. This +# allows the algorithms to be built as modules when all the filesystems are. +config FS_ENCRYPTION_ALGS + tristate + select CRYPTO_AES + select CRYPTO_CBC + select CRYPTO_CTS + select CRYPTO_ECB + select CRYPTO_HMAC + select CRYPTO_SHA256 + select CRYPTO_SHA512 + select CRYPTO_XTS diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c index 1f4b8a277060..4fa18fff9c4e 100644 --- a/fs/crypto/bio.c +++ b/fs/crypto/bio.c @@ -41,53 +41,101 @@ void fscrypt_decrypt_bio(struct bio *bio) } EXPORT_SYMBOL(fscrypt_decrypt_bio); +/** + * fscrypt_zeroout_range() - zero out a range of blocks in an encrypted file + * @inode: the file's inode + * @lblk: the first file logical block to zero out + * @pblk: the first filesystem physical block to zero out + * @len: number of blocks to zero out + * + * Zero out filesystem blocks in an encrypted regular file on-disk, i.e. write + * ciphertext blocks which decrypt to the all-zeroes block. The blocks must be + * both logically and physically contiguous. It's also assumed that the + * filesystem only uses a single block device, ->s_bdev. + * + * Note that since each block uses a different IV, this involves writing a + * different ciphertext to each block; we can't simply reuse the same one. + * + * Return: 0 on success; -errno on failure. + */ int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk, - sector_t pblk, unsigned int len) + sector_t pblk, unsigned int len) { const unsigned int blockbits = inode->i_blkbits; const unsigned int blocksize = 1 << blockbits; - struct page *ciphertext_page; + const unsigned int blocks_per_page_bits = PAGE_SHIFT - blockbits; + const unsigned int blocks_per_page = 1 << blocks_per_page_bits; + struct page *pages[16]; /* write up to 16 pages at a time */ + unsigned int nr_pages; + unsigned int i; + unsigned int offset; struct bio *bio; - int ret, err = 0; + int ret, err; - ciphertext_page = fscrypt_alloc_bounce_page(GFP_NOWAIT); - if (!ciphertext_page) - return -ENOMEM; + if (len == 0) + return 0; - while (len--) { - err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk, - ZERO_PAGE(0), ciphertext_page, - blocksize, 0, GFP_NOFS); - if (err) - goto errout; + BUILD_BUG_ON(ARRAY_SIZE(pages) > BIO_MAX_PAGES); + nr_pages = min_t(unsigned int, ARRAY_SIZE(pages), + (len + blocks_per_page - 1) >> blocks_per_page_bits); - bio = bio_alloc(GFP_NOWAIT, 1); - if (!bio) { - err = -ENOMEM; - goto errout; - } + /* + * We need at least one page for ciphertext. Allocate the first one + * from a mempool, with __GFP_DIRECT_RECLAIM set so that it can't fail. + * + * Any additional page allocations are allowed to fail, as they only + * help performance, and waiting on the mempool for them could deadlock. + */ + for (i = 0; i < nr_pages; i++) { + pages[i] = fscrypt_alloc_bounce_page(i == 0 ? GFP_NOFS : + GFP_NOWAIT | __GFP_NOWARN); + if (!pages[i]) + break; + } + nr_pages = i; + if (WARN_ON(nr_pages <= 0)) + return -EINVAL; + + /* This always succeeds since __GFP_DIRECT_RECLAIM is set. */ + bio = bio_alloc(GFP_NOFS, nr_pages); + + do { bio_set_dev(bio, inode->i_sb->s_bdev); bio->bi_iter.bi_sector = pblk << (blockbits - 9); bio_set_op_attrs(bio, REQ_OP_WRITE, 0); - ret = bio_add_page(bio, ciphertext_page, blocksize, 0); - if (WARN_ON(ret != blocksize)) { - /* should never happen! */ - bio_put(bio); - err = -EIO; - goto errout; - } + + i = 0; + offset = 0; + do { + err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk, + ZERO_PAGE(0), pages[i], + blocksize, offset, GFP_NOFS); + if (err) + goto out; + lblk++; + pblk++; + len--; + offset += blocksize; + if (offset == PAGE_SIZE || len == 0) { + ret = bio_add_page(bio, pages[i++], offset, 0); + if (WARN_ON(ret != offset)) { + err = -EIO; + goto out; + } + offset = 0; + } + } while (i != nr_pages && len != 0); + err = submit_bio_wait(bio); - if (err == 0 && bio->bi_status) - err = -EIO; - bio_put(bio); if (err) - goto errout; - lblk++; - pblk++; - } + goto out; + bio_reset(bio); + } while (len != 0); err = 0; -errout: - fscrypt_free_bounce_page(ciphertext_page); +out: + bio_put(bio); + for (i = 0; i < nr_pages; i++) + fscrypt_free_bounce_page(pages[i]); return err; } EXPORT_SYMBOL(fscrypt_zeroout_range); diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c index 3719efa546c6..1ecaac7ee3cb 100644 --- a/fs/crypto/crypto.c +++ b/fs/crypto/crypto.c @@ -25,8 +25,6 @@ #include <linux/module.h> #include <linux/scatterlist.h> #include <linux/ratelimit.h> -#include <linux/dcache.h> -#include <linux/namei.h> #include <crypto/skcipher.h> #include "fscrypt_private.h" @@ -140,7 +138,7 @@ int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw, * multiple of the filesystem's block size. * @offs: Byte offset within @page of the first block to encrypt. Must be * a multiple of the filesystem's block size. - * @gfp_flags: Memory allocation flags + * @gfp_flags: Memory allocation flags. See details below. * * A new bounce page is allocated, and the specified block(s) are encrypted into * it. In the bounce page, the ciphertext block(s) will be located at the same @@ -150,6 +148,11 @@ int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw, * * This is for use by the filesystem's ->writepages() method. * + * The bounce page allocation is mempool-backed, so it will always succeed when + * @gfp_flags includes __GFP_DIRECT_RECLAIM, e.g. when it's GFP_NOFS. However, + * only the first page of each bio can be allocated this way. To prevent + * deadlocks, for any additional pages a mask like GFP_NOWAIT must be used. + * * Return: the new encrypted bounce page on success; an ERR_PTR() on failure */ struct page *fscrypt_encrypt_pagecache_blocks(struct page *page, @@ -286,54 +289,6 @@ int fscrypt_decrypt_block_inplace(const struct inode *inode, struct page *page, } EXPORT_SYMBOL(fscrypt_decrypt_block_inplace); -/* - * Validate dentries in encrypted directories to make sure we aren't potentially - * caching stale dentries after a key has been added. - */ -static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags) -{ - struct dentry *dir; - int err; - int valid; - - /* - * Plaintext names are always valid, since fscrypt doesn't support - * reverting to ciphertext names without evicting the directory's inode - * -- which implies eviction of the dentries in the directory. - */ - if (!(dentry->d_flags & DCACHE_ENCRYPTED_NAME)) - return 1; - - /* - * Ciphertext name; valid if the directory's key is still unavailable. - * - * Although fscrypt forbids rename() on ciphertext names, we still must - * use dget_parent() here rather than use ->d_parent directly. That's - * because a corrupted fs image may contain directory hard links, which - * the VFS handles by moving the directory's dentry tree in the dcache - * each time ->lookup() finds the directory and it already has a dentry - * elsewhere. Thus ->d_parent can be changing, and we must safely grab - * a reference to some ->d_parent to prevent it from being freed. - */ - - if (flags & LOOKUP_RCU) - return -ECHILD; - - dir = dget_parent(dentry); - err = fscrypt_get_encryption_info(d_inode(dir)); - valid = !fscrypt_has_encryption_key(d_inode(dir)); - dput(dir); - - if (err < 0) - return err; - - return valid; -} - -const struct dentry_operations fscrypt_d_ops = { - .d_revalidate = fscrypt_d_revalidate, -}; - /** * fscrypt_initialize() - allocate major buffers for fs encryption. * @cop_flags: fscrypt operations flags diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c index 3da3707c10e3..4c212442a8f7 100644 --- a/fs/crypto/fname.c +++ b/fs/crypto/fname.c @@ -11,10 +11,87 @@ * This has not yet undergone a rigorous security audit. */ +#include <linux/namei.h> #include <linux/scatterlist.h> +#include <crypto/hash.h> +#include <crypto/sha.h> #include <crypto/skcipher.h> #include "fscrypt_private.h" +/** + * struct fscrypt_nokey_name - identifier for directory entry when key is absent + * + * When userspace lists an encrypted directory without access to the key, the + * filesystem must present a unique "no-key name" for each filename that allows + * it to find the directory entry again if requested. Naively, that would just + * mean using the ciphertext filenames. However, since the ciphertext filenames + * can contain illegal characters ('\0' and '/'), they must be encoded in some + * way. We use base64. But that can cause names to exceed NAME_MAX (255 + * bytes), so we also need to use a strong hash to abbreviate long names. + * + * The filesystem may also need another kind of hash, the "dirhash", to quickly + * find the directory entry. Since filesystems normally compute the dirhash + * over the on-disk filename (i.e. the ciphertext), it's not computable from + * no-key names that abbreviate the ciphertext using the strong hash to fit in + * NAME_MAX. It's also not computable if it's a keyed hash taken over the + * plaintext (but it may still be available in the on-disk directory entry); + * casefolded directories use this type of dirhash. At least in these cases, + * each no-key name must include the name's dirhash too. + * + * To meet all these requirements, we base64-encode the following + * variable-length structure. It contains the dirhash, or 0's if the filesystem + * didn't provide one; up to 149 bytes of the ciphertext name; and for + * ciphertexts longer than 149 bytes, also the SHA-256 of the remaining bytes. + * + * This ensures that each no-key name contains everything needed to find the + * directory entry again, contains only legal characters, doesn't exceed + * NAME_MAX, is unambiguous unless there's a SHA-256 collision, and that we only + * take the performance hit of SHA-256 on very long filenames (which are rare). + */ +struct fscrypt_nokey_name { + u32 dirhash[2]; + u8 bytes[149]; + u8 sha256[SHA256_DIGEST_SIZE]; +}; /* 189 bytes => 252 bytes base64-encoded, which is <= NAME_MAX (255) */ + +/* + * Decoded size of max-size nokey name, i.e. a name that was abbreviated using + * the strong hash and thus includes the 'sha256' field. This isn't simply + * sizeof(struct fscrypt_nokey_name), as the padding at the end isn't included. + */ +#define FSCRYPT_NOKEY_NAME_MAX offsetofend(struct fscrypt_nokey_name, sha256) + +static struct crypto_shash *sha256_hash_tfm; + +static int fscrypt_do_sha256(const u8 *data, unsigned int data_len, u8 *result) +{ + struct crypto_shash *tfm = READ_ONCE(sha256_hash_tfm); + + if (unlikely(!tfm)) { + struct crypto_shash *prev_tfm; + + tfm = crypto_alloc_shash("sha256", 0, 0); + if (IS_ERR(tfm)) { + fscrypt_err(NULL, + "Error allocating SHA-256 transform: %ld", + PTR_ERR(tfm)); + return PTR_ERR(tfm); + } + prev_tfm = cmpxchg(&sha256_hash_tfm, NULL, tfm); + if (prev_tfm) { + crypto_free_shash(tfm); + tfm = prev_tfm; + } + } + { + SHASH_DESC_ON_STACK(desc, tfm); + + desc->tfm = tfm; + + return crypto_shash_digest(desc, data, data_len, result); + } +} + static inline bool fscrypt_is_dot_dotdot(const struct qstr *str) { if (str->len == 1 && str->name[0] == '.') @@ -27,19 +104,19 @@ static inline bool fscrypt_is_dot_dotdot(const struct qstr *str) } /** - * fname_encrypt() - encrypt a filename + * fscrypt_fname_encrypt() - encrypt a filename * * 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 */ -int fname_encrypt(struct inode *inode, const struct qstr *iname, - u8 *out, unsigned int olen) +int fscrypt_fname_encrypt(const 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; + const struct fscrypt_info *ci = inode->i_crypt_info; struct crypto_skcipher *tfm = ci->ci_ctfm; union fscrypt_iv iv; struct scatterlist sg; @@ -85,14 +162,14 @@ int fname_encrypt(struct inode *inode, const struct qstr *iname, * * Return: 0 on success, -errno on failure */ -static int fname_decrypt(struct inode *inode, - const struct fscrypt_str *iname, - struct fscrypt_str *oname) +static int fname_decrypt(const struct inode *inode, + const struct fscrypt_str *iname, + struct fscrypt_str *oname) { struct skcipher_request *req = NULL; DECLARE_CRYPTO_WAIT(wait); struct scatterlist src_sg, dst_sg; - struct fscrypt_info *ci = inode->i_crypt_info; + const struct fscrypt_info *ci = inode->i_crypt_info; struct crypto_skcipher *tfm = ci->ci_ctfm; union fscrypt_iv iv; int res; @@ -206,9 +283,7 @@ int fscrypt_fname_alloc_buffer(const struct inode *inode, u32 max_encrypted_len, struct fscrypt_str *crypto_str) { - const u32 max_encoded_len = - max_t(u32, BASE64_CHARS(FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE), - 1 + BASE64_CHARS(sizeof(struct fscrypt_digested_name))); + const u32 max_encoded_len = BASE64_CHARS(FSCRYPT_NOKEY_NAME_MAX); u32 max_presented_len; max_presented_len = max(max_encoded_len, max_encrypted_len); @@ -241,19 +316,21 @@ EXPORT_SYMBOL(fscrypt_fname_free_buffer); * * The caller must have allocated sufficient memory for the @oname string. * - * If the key is available, we'll decrypt the disk name; otherwise, we'll encode - * it for presentation. Short names are directly base64-encoded, while long - * names are encoded in fscrypt_digested_name format. + * If the key is available, we'll decrypt the disk name. Otherwise, we'll + * encode it for presentation in fscrypt_nokey_name format. + * See struct fscrypt_nokey_name for details. * * Return: 0 on success, -errno on failure */ -int fscrypt_fname_disk_to_usr(struct inode *inode, - u32 hash, u32 minor_hash, - const struct fscrypt_str *iname, - struct fscrypt_str *oname) +int fscrypt_fname_disk_to_usr(const 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); - struct fscrypt_digested_name digested_name; + struct fscrypt_nokey_name nokey_name; + u32 size; /* size of the unencoded no-key name */ + int err; if (fscrypt_is_dot_dotdot(&qname)) { oname->name[0] = '.'; @@ -268,24 +345,37 @@ int fscrypt_fname_disk_to_usr(struct inode *inode, if (fscrypt_has_encryption_key(inode)) return fname_decrypt(inode, iname, oname); - if (iname->len <= FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE) { - oname->len = base64_encode(iname->name, iname->len, - oname->name); - return 0; - } + /* + * Sanity check that struct fscrypt_nokey_name doesn't have padding + * between fields and that its encoded size never exceeds NAME_MAX. + */ + BUILD_BUG_ON(offsetofend(struct fscrypt_nokey_name, dirhash) != + offsetof(struct fscrypt_nokey_name, bytes)); + BUILD_BUG_ON(offsetofend(struct fscrypt_nokey_name, bytes) != + offsetof(struct fscrypt_nokey_name, sha256)); + BUILD_BUG_ON(BASE64_CHARS(FSCRYPT_NOKEY_NAME_MAX) > NAME_MAX); + if (hash) { - digested_name.hash = hash; - digested_name.minor_hash = minor_hash; + nokey_name.dirhash[0] = hash; + nokey_name.dirhash[1] = minor_hash; + } else { + nokey_name.dirhash[0] = 0; + nokey_name.dirhash[1] = 0; + } + if (iname->len <= sizeof(nokey_name.bytes)) { + memcpy(nokey_name.bytes, iname->name, iname->len); + size = offsetof(struct fscrypt_nokey_name, bytes[iname->len]); } else { - digested_name.hash = 0; - digested_name.minor_hash = 0; + memcpy(nokey_name.bytes, iname->name, sizeof(nokey_name.bytes)); + /* Compute strong hash of remaining part of name. */ + err = fscrypt_do_sha256(&iname->name[sizeof(nokey_name.bytes)], + iname->len - sizeof(nokey_name.bytes), + nokey_name.sha256); + if (err) + return err; + size = FSCRYPT_NOKEY_NAME_MAX; } - memcpy(digested_name.digest, - FSCRYPT_FNAME_DIGEST(iname->name, iname->len), - FSCRYPT_FNAME_DIGEST_SIZE); - oname->name[0] = '_'; - oname->len = 1 + base64_encode((const u8 *)&digested_name, - sizeof(digested_name), oname->name + 1); + oname->len = base64_encode((const u8 *)&nokey_name, size, oname->name); return 0; } EXPORT_SYMBOL(fscrypt_fname_disk_to_usr); @@ -306,8 +396,7 @@ EXPORT_SYMBOL(fscrypt_fname_disk_to_usr); * get the disk_name. * * Else, for keyless @lookup operations, @iname is the presented ciphertext, so - * we decode it to get either the ciphertext disk_name (for short names) or the - * fscrypt_digested_name (for long names). Non-@lookup operations will be + * we decode it to get the fscrypt_nokey_name. Non-@lookup operations will be * impossible in this case, so we fail them with ENOKEY. * * If successful, fscrypt_free_filename() must be called later to clean up. @@ -317,8 +406,8 @@ EXPORT_SYMBOL(fscrypt_fname_disk_to_usr); int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, int lookup, struct fscrypt_name *fname) { + struct fscrypt_nokey_name *nokey_name; int ret; - int digested; memset(fname, 0, sizeof(struct fscrypt_name)); fname->usr_fname = iname; @@ -342,8 +431,8 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, if (!fname->crypto_buf.name) return -ENOMEM; - ret = fname_encrypt(dir, iname, fname->crypto_buf.name, - fname->crypto_buf.len); + ret = fscrypt_fname_encrypt(dir, iname, fname->crypto_buf.name, + fname->crypto_buf.len); if (ret) goto errout; fname->disk_name.name = fname->crypto_buf.name; @@ -358,40 +447,31 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, * We don't have the key and we are doing a lookup; decode the * user-supplied name */ - if (iname->name[0] == '_') { - if (iname->len != - 1 + BASE64_CHARS(sizeof(struct fscrypt_digested_name))) - return -ENOENT; - digested = 1; - } else { - if (iname->len > - BASE64_CHARS(FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE)) - return -ENOENT; - digested = 0; - } - fname->crypto_buf.name = - kmalloc(max_t(size_t, FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE, - sizeof(struct fscrypt_digested_name)), - GFP_KERNEL); + if (iname->len > BASE64_CHARS(FSCRYPT_NOKEY_NAME_MAX)) + return -ENOENT; + + fname->crypto_buf.name = kmalloc(FSCRYPT_NOKEY_NAME_MAX, GFP_KERNEL); if (fname->crypto_buf.name == NULL) return -ENOMEM; - ret = base64_decode(iname->name + digested, iname->len - digested, - fname->crypto_buf.name); - if (ret < 0) { + ret = base64_decode(iname->name, iname->len, fname->crypto_buf.name); + if (ret < (int)offsetof(struct fscrypt_nokey_name, bytes[1]) || + (ret > offsetof(struct fscrypt_nokey_name, sha256) && + ret != FSCRYPT_NOKEY_NAME_MAX)) { ret = -ENOENT; goto errout; } fname->crypto_buf.len = ret; - if (digested) { - const struct fscrypt_digested_name *n = - (const void *)fname->crypto_buf.name; - fname->hash = n->hash; - fname->minor_hash = n->minor_hash; - } else { - fname->disk_name.name = fname->crypto_buf.name; - fname->disk_name.len = fname->crypto_buf.len; + + nokey_name = (void *)fname->crypto_buf.name; + fname->hash = nokey_name->dirhash[0]; + fname->minor_hash = nokey_name->dirhash[1]; + if (ret != FSCRYPT_NOKEY_NAME_MAX) { + /* The full ciphertext filename is available. */ + fname->disk_name.name = nokey_name->bytes; + fname->disk_name.len = + ret - offsetof(struct fscrypt_nokey_name, bytes); } return 0; @@ -400,3 +480,109 @@ errout: return ret; } EXPORT_SYMBOL(fscrypt_setup_filename); + +/** + * fscrypt_match_name() - test whether the given name matches a directory entry + * @fname: the name being searched for + * @de_name: the name from the directory entry + * @de_name_len: the length of @de_name in bytes + * + * Normally @fname->disk_name will be set, and in that case we simply compare + * that to the name stored in the directory entry. The only exception is that + * if we don't have the key for an encrypted directory and the name we're + * looking for is very long, then we won't have the full disk_name and instead + * we'll need to match against a fscrypt_nokey_name that includes a strong hash. + * + * Return: %true if the name matches, otherwise %false. + */ +bool fscrypt_match_name(const struct fscrypt_name *fname, + const u8 *de_name, u32 de_name_len) +{ + const struct fscrypt_nokey_name *nokey_name = + (const void *)fname->crypto_buf.name; + u8 sha256[SHA256_DIGEST_SIZE]; + + if (likely(fname->disk_name.name)) { + if (de_name_len != fname->disk_name.len) + return false; + return !memcmp(de_name, fname->disk_name.name, de_name_len); + } + if (de_name_len <= sizeof(nokey_name->bytes)) + return false; + if (memcmp(de_name, nokey_name->bytes, sizeof(nokey_name->bytes))) + return false; + if (fscrypt_do_sha256(&de_name[sizeof(nokey_name->bytes)], + de_name_len - sizeof(nokey_name->bytes), sha256)) + return false; + return !memcmp(sha256, nokey_name->sha256, sizeof(sha256)); +} +EXPORT_SYMBOL_GPL(fscrypt_match_name); + +/** + * fscrypt_fname_siphash() - calculate the SipHash of a filename + * @dir: the parent directory + * @name: the filename to calculate the SipHash of + * + * Given a plaintext filename @name and a directory @dir which uses SipHash as + * its dirhash method and has had its fscrypt key set up, this function + * calculates the SipHash of that name using the directory's secret dirhash key. + * + * Return: the SipHash of @name using the hash key of @dir + */ +u64 fscrypt_fname_siphash(const struct inode *dir, const struct qstr *name) +{ + const struct fscrypt_info *ci = dir->i_crypt_info; + + WARN_ON(!ci->ci_dirhash_key_initialized); + + return siphash(name->name, name->len, &ci->ci_dirhash_key); +} +EXPORT_SYMBOL_GPL(fscrypt_fname_siphash); + +/* + * Validate dentries in encrypted directories to make sure we aren't potentially + * caching stale dentries after a key has been added. + */ +static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags) +{ + struct dentry *dir; + int err; + int valid; + + /* + * Plaintext names are always valid, since fscrypt doesn't support + * reverting to ciphertext names without evicting the directory's inode + * -- which implies eviction of the dentries in the directory. + */ + if (!(dentry->d_flags & DCACHE_ENCRYPTED_NAME)) + return 1; + + /* + * Ciphertext name; valid if the directory's key is still unavailable. + * + * Although fscrypt forbids rename() on ciphertext names, we still must + * use dget_parent() here rather than use ->d_parent directly. That's + * because a corrupted fs image may contain directory hard links, which + * the VFS handles by moving the directory's dentry tree in the dcache + * each time ->lookup() finds the directory and it already has a dentry + * elsewhere. Thus ->d_parent can be changing, and we must safely grab + * a reference to some ->d_parent to prevent it from being freed. + */ + + if (flags & LOOKUP_RCU) + return -ECHILD; + + dir = dget_parent(dentry); + err = fscrypt_get_encryption_info(d_inode(dir)); + valid = !fscrypt_has_encryption_key(d_inode(dir)); + dput(dir); + + if (err < 0) + return err; + + return valid; +} + +const struct dentry_operations fscrypt_d_ops = { + .d_revalidate = fscrypt_d_revalidate, +}; diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h index 130b50e5a011..9aae851409e5 100644 --- a/fs/crypto/fscrypt_private.h +++ b/fs/crypto/fscrypt_private.h @@ -12,6 +12,7 @@ #define _FSCRYPT_PRIVATE_H #include <linux/fscrypt.h> +#include <linux/siphash.h> #include <crypto/hash.h> #define CONST_STRLEN(str) (sizeof(str) - 1) @@ -136,12 +137,6 @@ fscrypt_policy_flags(const union fscrypt_policy *policy) BUG(); } -static inline bool -fscrypt_is_direct_key_policy(const union fscrypt_policy *policy) -{ - return fscrypt_policy_flags(policy) & FSCRYPT_POLICY_FLAG_DIRECT_KEY; -} - /** * For encrypted symlinks, the ciphertext length is stored at the beginning * of the string in little-endian format. @@ -194,6 +189,14 @@ struct fscrypt_info { */ struct fscrypt_direct_key *ci_direct_key; + /* + * This inode's hash key for filenames. This is a 128-bit SipHash-2-4 + * key. This is only set for directories that use a keyed dirhash over + * the plaintext filenames -- currently just casefolded directories. + */ + siphash_key_t ci_dirhash_key; + bool ci_dirhash_key_initialized; + /* The encryption policy used by this inode */ union fscrypt_policy ci_policy; @@ -206,24 +209,6 @@ typedef enum { FS_ENCRYPT, } fscrypt_direction_t; -static inline bool fscrypt_valid_enc_modes(u32 contents_mode, - u32 filenames_mode) -{ - if (contents_mode == FSCRYPT_MODE_AES_128_CBC && - filenames_mode == FSCRYPT_MODE_AES_128_CTS) - return true; - - if (contents_mode == FSCRYPT_MODE_AES_256_XTS && - filenames_mode == FSCRYPT_MODE_AES_256_CTS) - return true; - - if (contents_mode == FSCRYPT_MODE_ADIANTUM && - filenames_mode == FSCRYPT_MODE_ADIANTUM) - return true; - - return false; -} - /* crypto.c */ extern struct kmem_cache *fscrypt_info_cachep; extern int fscrypt_initialize(unsigned int cop_flags); @@ -233,7 +218,6 @@ extern int fscrypt_crypt_block(const struct inode *inode, unsigned int len, unsigned int offs, gfp_t gfp_flags); extern struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags); -extern const struct dentry_operations fscrypt_d_ops; extern void __printf(3, 4) __cold fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...); @@ -260,11 +244,13 @@ void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num, const struct fscrypt_info *ci); /* fname.c */ -extern int fname_encrypt(struct inode *inode, const struct qstr *iname, - u8 *out, unsigned int olen); +extern int fscrypt_fname_encrypt(const 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); +extern const struct dentry_operations fscrypt_d_ops; /* hkdf.c */ @@ -283,11 +269,12 @@ extern int fscrypt_init_hkdf(struct fscrypt_hkdf *hkdf, const u8 *master_key, * output doesn't reveal another. */ #define HKDF_CONTEXT_KEY_IDENTIFIER 1 -#define HKDF_CONTEXT_PER_FILE_KEY 2 +#define HKDF_CONTEXT_PER_FILE_ENC_KEY 2 #define HKDF_CONTEXT_DIRECT_KEY 3 #define HKDF_CONTEXT_IV_INO_LBLK_64_KEY 4 +#define HKDF_CONTEXT_DIRHASH_KEY 5 -extern int fscrypt_hkdf_expand(struct fscrypt_hkdf *hkdf, u8 context, +extern int fscrypt_hkdf_expand(const struct fscrypt_hkdf *hkdf, u8 context, const u8 *info, unsigned int infolen, u8 *okm, unsigned int okmlen); @@ -448,18 +435,17 @@ struct fscrypt_mode { int logged_impl_name; }; -static inline bool -fscrypt_mode_supports_direct_key(const struct fscrypt_mode *mode) -{ - return mode->ivsize >= offsetofend(union fscrypt_iv, nonce); -} +extern struct fscrypt_mode fscrypt_modes[]; extern struct crypto_skcipher * fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key, const struct inode *inode); -extern int fscrypt_set_derived_key(struct fscrypt_info *ci, - const u8 *derived_key); +extern int fscrypt_set_per_file_enc_key(struct fscrypt_info *ci, + const u8 *raw_key); + +extern int fscrypt_derive_dirhash_key(struct fscrypt_info *ci, + const struct fscrypt_master_key *mk); /* keysetup_v1.c */ diff --git a/fs/crypto/hkdf.c b/fs/crypto/hkdf.c index f21873e1b467..efb95bd19a89 100644 --- a/fs/crypto/hkdf.c +++ b/fs/crypto/hkdf.c @@ -112,7 +112,7 @@ out: * adds to its application-specific info strings to guarantee that it doesn't * accidentally repeat an info string when using HKDF for different purposes.) */ -int fscrypt_hkdf_expand(struct fscrypt_hkdf *hkdf, u8 context, +int fscrypt_hkdf_expand(const struct fscrypt_hkdf *hkdf, u8 context, const u8 *info, unsigned int infolen, u8 *okm, unsigned int okmlen) { diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c index bb3b7fcfdd48..5ef861742921 100644 --- a/fs/crypto/hooks.c +++ b/fs/crypto/hooks.c @@ -5,6 +5,8 @@ * Encryption hooks for higher-level filesystem operations. */ +#include <linux/key.h> + #include "fscrypt_private.h" /** @@ -122,6 +124,48 @@ int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry, } EXPORT_SYMBOL_GPL(__fscrypt_prepare_lookup); +/** + * fscrypt_prepare_setflags() - prepare to change flags with FS_IOC_SETFLAGS + * @inode: the inode on which flags are being changed + * @oldflags: the old flags + * @flags: the new flags + * + * The caller should be holding i_rwsem for write. + * + * Return: 0 on success; -errno if the flags change isn't allowed or if + * another error occurs. + */ +int fscrypt_prepare_setflags(struct inode *inode, + unsigned int oldflags, unsigned int flags) +{ + struct fscrypt_info *ci; + struct fscrypt_master_key *mk; + int err; + + /* + * When the CASEFOLD flag is set on an encrypted directory, we must + * derive the secret key needed for the dirhash. This is only possible + * if the directory uses a v2 encryption policy. + */ + if (IS_ENCRYPTED(inode) && (flags & ~oldflags & FS_CASEFOLD_FL)) { + err = fscrypt_require_key(inode); + if (err) + return err; + ci = inode->i_crypt_info; + if (ci->ci_policy.version != FSCRYPT_POLICY_V2) + return -EINVAL; + mk = ci->ci_master_key->payload.data[0]; + down_read(&mk->mk_secret_sem); + if (is_master_key_secret_present(&mk->mk_secret)) + err = fscrypt_derive_dirhash_key(ci, mk); + else + err = -ENOKEY; + up_read(&mk->mk_secret_sem); + return err; + } + return 0; +} + int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len, unsigned int max_len, struct fscrypt_str *disk_link) @@ -188,7 +232,8 @@ int __fscrypt_encrypt_symlink(struct inode *inode, const char *target, ciphertext_len = disk_link->len - sizeof(*sd); sd->len = cpu_to_le16(ciphertext_len); - err = fname_encrypt(inode, &iname, sd->encrypted_path, ciphertext_len); + err = fscrypt_fname_encrypt(inode, &iname, sd->encrypted_path, + ciphertext_len); if (err) goto err_free_sd; diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c index 040df1f5e1c8..ab41b25d4fa1 100644 --- a/fs/crypto/keyring.c +++ b/fs/crypto/keyring.c @@ -151,7 +151,7 @@ static struct key *search_fscrypt_keyring(struct key *keyring, } #define FSCRYPT_FS_KEYRING_DESCRIPTION_SIZE \ - (CONST_STRLEN("fscrypt-") + FIELD_SIZEOF(struct super_block, s_id)) + (CONST_STRLEN("fscrypt-") + sizeof_field(struct super_block, s_id)) #define FSCRYPT_MK_DESCRIPTION_SIZE (2 * FSCRYPT_KEY_IDENTIFIER_SIZE + 1) @@ -465,6 +465,109 @@ out_unlock: return err; } +static int fscrypt_provisioning_key_preparse(struct key_preparsed_payload *prep) +{ + const struct fscrypt_provisioning_key_payload *payload = prep->data; + + if (prep->datalen < sizeof(*payload) + FSCRYPT_MIN_KEY_SIZE || + prep->datalen > sizeof(*payload) + FSCRYPT_MAX_KEY_SIZE) + return -EINVAL; + + if (payload->type != FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR && + payload->type != FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER) + return -EINVAL; + + if (payload->__reserved) + return -EINVAL; + + prep->payload.data[0] = kmemdup(payload, prep->datalen, GFP_KERNEL); + if (!prep->payload.data[0]) + return -ENOMEM; + + prep->quotalen = prep->datalen; + return 0; +} + +static void fscrypt_provisioning_key_free_preparse( + struct key_preparsed_payload *prep) +{ + kzfree(prep->payload.data[0]); +} + +static void fscrypt_provisioning_key_describe(const struct key *key, + struct seq_file *m) +{ + seq_puts(m, key->description); + if (key_is_positive(key)) { + const struct fscrypt_provisioning_key_payload *payload = + key->payload.data[0]; + + seq_printf(m, ": %u [%u]", key->datalen, payload->type); + } +} + +static void fscrypt_provisioning_key_destroy(struct key *key) +{ + kzfree(key->payload.data[0]); +} + +static struct key_type key_type_fscrypt_provisioning = { + .name = "fscrypt-provisioning", + .preparse = fscrypt_provisioning_key_preparse, + .free_preparse = fscrypt_provisioning_key_free_preparse, + .instantiate = generic_key_instantiate, + .describe = fscrypt_provisioning_key_describe, + .destroy = fscrypt_provisioning_key_destroy, +}; + +/* + * Retrieve the raw key from the Linux keyring key specified by 'key_id', and + * store it into 'secret'. + * + * The key must be of type "fscrypt-provisioning" and must have the field + * fscrypt_provisioning_key_payload::type set to 'type', indicating that it's + * only usable with fscrypt with the particular KDF version identified by + * 'type'. We don't use the "logon" key type because there's no way to + * completely restrict the use of such keys; they can be used by any kernel API + * that accepts "logon" keys and doesn't require a specific service prefix. + * + * The ability to specify the key via Linux keyring key is intended for cases + * where userspace needs to re-add keys after the filesystem is unmounted and + * re-mounted. Most users should just provide the raw key directly instead. + */ +static int get_keyring_key(u32 key_id, u32 type, + struct fscrypt_master_key_secret *secret) +{ + key_ref_t ref; + struct key *key; + const struct fscrypt_provisioning_key_payload *payload; + int err; + + ref = lookup_user_key(key_id, 0, KEY_NEED_SEARCH); + if (IS_ERR(ref)) + return PTR_ERR(ref); + key = key_ref_to_ptr(ref); + + if (key->type != &key_type_fscrypt_provisioning) + goto bad_key; + payload = key->payload.data[0]; + + /* Don't allow fscrypt v1 keys to be used as v2 keys and vice versa. */ + if (payload->type != type) + goto bad_key; + + secret->size = key->datalen - sizeof(*payload); + memcpy(secret->raw, payload->raw, secret->size); + err = 0; + goto out_put; + +bad_key: + err = -EKEYREJECTED; +out_put: + key_ref_put(ref); + return err; +} + /* * Add a master encryption key to the filesystem, causing all files which were * encrypted with it to appear "unlocked" (decrypted) when accessed. @@ -503,18 +606,25 @@ int fscrypt_ioctl_add_key(struct file *filp, void __user *_uarg) if (!valid_key_spec(&arg.key_spec)) return -EINVAL; - if (arg.raw_size < FSCRYPT_MIN_KEY_SIZE || - arg.raw_size > FSCRYPT_MAX_KEY_SIZE) - return -EINVAL; - if (memchr_inv(arg.__reserved, 0, sizeof(arg.__reserved))) return -EINVAL; memset(&secret, 0, sizeof(secret)); - secret.size = arg.raw_size; - err = -EFAULT; - if (copy_from_user(secret.raw, uarg->raw, secret.size)) - goto out_wipe_secret; + if (arg.key_id) { + if (arg.raw_size != 0) + return -EINVAL; + err = get_keyring_key(arg.key_id, arg.key_spec.type, &secret); + if (err) + goto out_wipe_secret; + } else { + if (arg.raw_size < FSCRYPT_MIN_KEY_SIZE || + arg.raw_size > FSCRYPT_MAX_KEY_SIZE) + return -EINVAL; + secret.size = arg.raw_size; + err = -EFAULT; + if (copy_from_user(secret.raw, uarg->raw, secret.size)) + goto out_wipe_secret; + } switch (arg.key_spec.type) { case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR: @@ -666,9 +776,6 @@ static int check_for_busy_inodes(struct super_block *sb, struct list_head *pos; size_t busy_count = 0; unsigned long ino; - struct dentry *dentry; - char _path[256]; - char *path = NULL; spin_lock(&mk->mk_decrypted_inodes_lock); @@ -687,22 +794,14 @@ static int check_for_busy_inodes(struct super_block *sb, struct fscrypt_info, ci_master_key_link)->ci_inode; ino = inode->i_ino; - dentry = d_find_alias(inode); } spin_unlock(&mk->mk_decrypted_inodes_lock); - if (dentry) { - path = dentry_path(dentry, _path, sizeof(_path)); - dput(dentry); - } - if (IS_ERR_OR_NULL(path)) - path = "(unknown)"; - fscrypt_warn(NULL, - "%s: %zu inode(s) still busy after removing key with %s %*phN, including ino %lu (%s)", + "%s: %zu inode(s) still busy after removing key with %s %*phN, including ino %lu", sb->s_id, busy_count, master_key_spec_type(&mk->mk_spec), master_key_spec_len(&mk->mk_spec), (u8 *)&mk->mk_spec.u, - ino, path); + ino); return -EBUSY; } @@ -978,8 +1077,14 @@ int __init fscrypt_init_keyring(void) if (err) goto err_unregister_fscrypt; + err = register_key_type(&key_type_fscrypt_provisioning); + if (err) + goto err_unregister_fscrypt_user; + return 0; +err_unregister_fscrypt_user: + unregister_key_type(&key_type_fscrypt_user); err_unregister_fscrypt: unregister_key_type(&key_type_fscrypt); return err; diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c index f577bb6613f9..65cb09fa6ead 100644 --- a/fs/crypto/keysetup.c +++ b/fs/crypto/keysetup.c @@ -13,7 +13,7 @@ #include "fscrypt_private.h" -static struct fscrypt_mode available_modes[] = { +struct fscrypt_mode fscrypt_modes[] = { [FSCRYPT_MODE_AES_256_XTS] = { .friendly_name = "AES-256-XTS", .cipher_str = "xts(aes)", @@ -51,10 +51,10 @@ select_encryption_mode(const union fscrypt_policy *policy, const struct inode *inode) { if (S_ISREG(inode->i_mode)) - return &available_modes[fscrypt_policy_contents_mode(policy)]; + return &fscrypt_modes[fscrypt_policy_contents_mode(policy)]; if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) - return &available_modes[fscrypt_policy_fnames_mode(policy)]; + return &fscrypt_modes[fscrypt_policy_fnames_mode(policy)]; WARN_ONCE(1, "fscrypt: filesystem tried to load encryption info for inode %lu, which is not encryptable (file type %d)\n", inode->i_ino, (inode->i_mode & S_IFMT)); @@ -89,8 +89,11 @@ struct crypto_skcipher *fscrypt_allocate_skcipher(struct fscrypt_mode *mode, * first time a mode is used. */ pr_info("fscrypt: %s using implementation \"%s\"\n", - mode->friendly_name, - crypto_skcipher_alg(tfm)->base.cra_driver_name); + mode->friendly_name, crypto_skcipher_driver_name(tfm)); + } + if (WARN_ON(crypto_skcipher_ivsize(tfm) != mode->ivsize)) { + err = -EINVAL; + goto err_free_tfm; } crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS); err = crypto_skcipher_setkey(tfm, raw_key, mode->keysize); @@ -104,12 +107,12 @@ err_free_tfm: return ERR_PTR(err); } -/* Given the per-file key, set up the file's crypto transform object */ -int fscrypt_set_derived_key(struct fscrypt_info *ci, const u8 *derived_key) +/* Given a per-file encryption key, set up the file's crypto transform object */ +int fscrypt_set_per_file_enc_key(struct fscrypt_info *ci, const u8 *raw_key) { struct crypto_skcipher *tfm; - tfm = fscrypt_allocate_skcipher(ci->ci_mode, derived_key, ci->ci_inode); + tfm = fscrypt_allocate_skcipher(ci->ci_mode, raw_key, ci->ci_inode); if (IS_ERR(tfm)) return PTR_ERR(tfm); @@ -118,15 +121,15 @@ int fscrypt_set_derived_key(struct fscrypt_info *ci, const u8 *derived_key) return 0; } -static int setup_per_mode_key(struct fscrypt_info *ci, - struct fscrypt_master_key *mk, - struct crypto_skcipher **tfms, - u8 hkdf_context, bool include_fs_uuid) +static int setup_per_mode_enc_key(struct fscrypt_info *ci, + struct fscrypt_master_key *mk, + struct crypto_skcipher **tfms, + u8 hkdf_context, bool include_fs_uuid) { const struct inode *inode = ci->ci_inode; const struct super_block *sb = inode->i_sb; struct fscrypt_mode *mode = ci->ci_mode; - u8 mode_num = mode - available_modes; + const u8 mode_num = mode - fscrypt_modes; struct crypto_skcipher *tfm, *prev_tfm; u8 mode_key[FSCRYPT_MAX_KEY_SIZE]; u8 hkdf_info[sizeof(mode_num) + sizeof(sb->s_uuid)]; @@ -171,29 +174,37 @@ done: return 0; } +int fscrypt_derive_dirhash_key(struct fscrypt_info *ci, + const struct fscrypt_master_key *mk) +{ + int err; + + err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf, HKDF_CONTEXT_DIRHASH_KEY, + ci->ci_nonce, FS_KEY_DERIVATION_NONCE_SIZE, + (u8 *)&ci->ci_dirhash_key, + sizeof(ci->ci_dirhash_key)); + if (err) + return err; + ci->ci_dirhash_key_initialized = true; + return 0; +} + static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci, struct fscrypt_master_key *mk) { - u8 derived_key[FSCRYPT_MAX_KEY_SIZE]; int err; if (ci->ci_policy.v2.flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) { /* - * DIRECT_KEY: instead of deriving per-file keys, the per-file - * nonce will be included in all the IVs. But unlike v1 - * policies, for v2 policies in this case we don't encrypt with - * the master key directly but rather derive a per-mode key. - * This ensures that the master key is consistently used only - * for HKDF, avoiding key reuse issues. + * DIRECT_KEY: instead of deriving per-file encryption keys, the + * per-file nonce will be included in all the IVs. But unlike + * v1 policies, for v2 policies in this case we don't encrypt + * with the master key directly but rather derive a per-mode + * encryption key. This ensures that the master key is + * consistently used only for HKDF, avoiding key reuse issues. */ - if (!fscrypt_mode_supports_direct_key(ci->ci_mode)) { - fscrypt_warn(ci->ci_inode, - "Direct key flag not allowed with %s", - ci->ci_mode->friendly_name); - return -EINVAL; - } - return setup_per_mode_key(ci, mk, mk->mk_direct_tfms, - HKDF_CONTEXT_DIRECT_KEY, false); + err = setup_per_mode_enc_key(ci, mk, mk->mk_direct_tfms, + HKDF_CONTEXT_DIRECT_KEY, false); } else if (ci->ci_policy.v2.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) { /* @@ -202,21 +213,34 @@ static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci, * the IVs. This format is optimized for use with inline * encryption hardware compliant with the UFS or eMMC standards. */ - return setup_per_mode_key(ci, mk, mk->mk_iv_ino_lblk_64_tfms, - HKDF_CONTEXT_IV_INO_LBLK_64_KEY, - true); + err = setup_per_mode_enc_key(ci, mk, mk->mk_iv_ino_lblk_64_tfms, + HKDF_CONTEXT_IV_INO_LBLK_64_KEY, + true); + } else { + u8 derived_key[FSCRYPT_MAX_KEY_SIZE]; + + err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf, + HKDF_CONTEXT_PER_FILE_ENC_KEY, + ci->ci_nonce, + FS_KEY_DERIVATION_NONCE_SIZE, + derived_key, ci->ci_mode->keysize); + if (err) + return err; + + err = fscrypt_set_per_file_enc_key(ci, derived_key); + memzero_explicit(derived_key, ci->ci_mode->keysize); } - - err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf, - HKDF_CONTEXT_PER_FILE_KEY, - ci->ci_nonce, FS_KEY_DERIVATION_NONCE_SIZE, - derived_key, ci->ci_mode->keysize); if (err) return err; - err = fscrypt_set_derived_key(ci, derived_key); - memzero_explicit(derived_key, ci->ci_mode->keysize); - return err; + /* Derive a secret dirhash key for directories that need it. */ + if (S_ISDIR(ci->ci_inode->i_mode) && IS_CASEFOLDED(ci->ci_inode)) { + err = fscrypt_derive_dirhash_key(ci, mk); + if (err) + return err; + } + + return 0; } /* diff --git a/fs/crypto/keysetup_v1.c b/fs/crypto/keysetup_v1.c index 5298ef22aa85..801b48c0cd7f 100644 --- a/fs/crypto/keysetup_v1.c +++ b/fs/crypto/keysetup_v1.c @@ -9,7 +9,7 @@ * This file implements compatibility functions for the original encryption * policy version ("v1"), including: * - * - Deriving per-file keys using the AES-128-ECB based KDF + * - Deriving per-file encryption keys using the AES-128-ECB based KDF * (rather than the new method of using HKDF-SHA512) * * - Retrieving fscrypt master keys from process-subscribed keyrings @@ -253,23 +253,8 @@ err_free_dk: static int setup_v1_file_key_direct(struct fscrypt_info *ci, const u8 *raw_master_key) { - const struct fscrypt_mode *mode = ci->ci_mode; struct fscrypt_direct_key *dk; - if (!fscrypt_mode_supports_direct_key(mode)) { - fscrypt_warn(ci->ci_inode, - "Direct key mode not allowed with %s", - mode->friendly_name); - return -EINVAL; - } - - if (ci->ci_policy.v1.contents_encryption_mode != - ci->ci_policy.v1.filenames_encryption_mode) { - fscrypt_warn(ci->ci_inode, - "Direct key mode not allowed with different contents and filenames modes"); - return -EINVAL; - } - dk = fscrypt_get_direct_key(ci, raw_master_key); if (IS_ERR(dk)) return PTR_ERR(dk); @@ -298,7 +283,7 @@ static int setup_v1_file_key_derived(struct fscrypt_info *ci, if (err) goto out; - err = fscrypt_set_derived_key(ci, derived_key); + err = fscrypt_set_per_file_enc_key(ci, derived_key); out: kzfree(derived_key); return err; diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c index 96f528071bed..cf2a9d26ef7d 100644 --- a/fs/crypto/policy.c +++ b/fs/crypto/policy.c @@ -29,6 +29,43 @@ bool fscrypt_policies_equal(const union fscrypt_policy *policy1, return !memcmp(policy1, policy2, fscrypt_policy_size(policy1)); } +static bool fscrypt_valid_enc_modes(u32 contents_mode, u32 filenames_mode) +{ + if (contents_mode == FSCRYPT_MODE_AES_256_XTS && + filenames_mode == FSCRYPT_MODE_AES_256_CTS) + return true; + + if (contents_mode == FSCRYPT_MODE_AES_128_CBC && + filenames_mode == FSCRYPT_MODE_AES_128_CTS) + return true; + + if (contents_mode == FSCRYPT_MODE_ADIANTUM && + filenames_mode == FSCRYPT_MODE_ADIANTUM) + return true; + + return false; +} + +static bool supported_direct_key_modes(const struct inode *inode, + u32 contents_mode, u32 filenames_mode) +{ + const struct fscrypt_mode *mode; + + if (contents_mode != filenames_mode) { + fscrypt_warn(inode, + "Direct key flag not allowed with different contents and filenames modes"); + return false; + } + mode = &fscrypt_modes[contents_mode]; + + if (mode->ivsize < offsetofend(union fscrypt_iv, nonce)) { + fscrypt_warn(inode, "Direct key flag not allowed with %s", + mode->friendly_name); + return false; + } + return true; +} + static bool supported_iv_ino_lblk_64_policy( const struct fscrypt_policy_v2 *policy, const struct inode *inode) @@ -63,13 +100,82 @@ static bool supported_iv_ino_lblk_64_policy( return true; } +static bool fscrypt_supported_v1_policy(const struct fscrypt_policy_v1 *policy, + const struct inode *inode) +{ + if (!fscrypt_valid_enc_modes(policy->contents_encryption_mode, + policy->filenames_encryption_mode)) { + fscrypt_warn(inode, + "Unsupported encryption modes (contents %d, filenames %d)", + policy->contents_encryption_mode, + policy->filenames_encryption_mode); + return false; + } + + if (policy->flags & ~(FSCRYPT_POLICY_FLAGS_PAD_MASK | + FSCRYPT_POLICY_FLAG_DIRECT_KEY)) { + fscrypt_warn(inode, "Unsupported encryption flags (0x%02x)", + policy->flags); + return false; + } + + if ((policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) && + !supported_direct_key_modes(inode, policy->contents_encryption_mode, + policy->filenames_encryption_mode)) + return false; + + if (IS_CASEFOLDED(inode)) { + /* With v1, there's no way to derive dirhash keys. */ + fscrypt_warn(inode, + "v1 policies can't be used on casefolded directories"); + return false; + } + + return true; +} + +static bool fscrypt_supported_v2_policy(const struct fscrypt_policy_v2 *policy, + const struct inode *inode) +{ + if (!fscrypt_valid_enc_modes(policy->contents_encryption_mode, + policy->filenames_encryption_mode)) { + fscrypt_warn(inode, + "Unsupported encryption modes (contents %d, filenames %d)", + policy->contents_encryption_mode, + policy->filenames_encryption_mode); + return false; + } + + if (policy->flags & ~FSCRYPT_POLICY_FLAGS_VALID) { + fscrypt_warn(inode, "Unsupported encryption flags (0x%02x)", + policy->flags); + return false; + } + + if ((policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) && + !supported_direct_key_modes(inode, policy->contents_encryption_mode, + policy->filenames_encryption_mode)) + return false; + + if ((policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) && + !supported_iv_ino_lblk_64_policy(policy, inode)) + return false; + + if (memchr_inv(policy->__reserved, 0, sizeof(policy->__reserved))) { + fscrypt_warn(inode, "Reserved bits set in encryption policy"); + return false; + } + + return true; +} + /** * fscrypt_supported_policy - check whether an encryption policy is supported * * Given an encryption policy, check whether all its encryption modes and other - * settings are supported by this kernel. (But we don't currently don't check - * for crypto API support here, so attempting to use an algorithm not configured - * into the crypto API will still fail later.) + * settings are supported by this kernel on the given inode. (But we don't + * currently don't check for crypto API support here, so attempting to use an + * algorithm not configured into the crypto API will still fail later.) * * Return: %true if supported, else %false */ @@ -77,60 +183,10 @@ bool fscrypt_supported_policy(const union fscrypt_policy *policy_u, const struct inode *inode) { switch (policy_u->version) { - case FSCRYPT_POLICY_V1: { - const struct fscrypt_policy_v1 *policy = &policy_u->v1; - - if (!fscrypt_valid_enc_modes(policy->contents_encryption_mode, - policy->filenames_encryption_mode)) { - fscrypt_warn(inode, - "Unsupported encryption modes (contents %d, filenames %d)", - policy->contents_encryption_mode, - policy->filenames_encryption_mode); - return false; - } - - if (policy->flags & ~(FSCRYPT_POLICY_FLAGS_PAD_MASK | - FSCRYPT_POLICY_FLAG_DIRECT_KEY)) { - fscrypt_warn(inode, - "Unsupported encryption flags (0x%02x)", - policy->flags); - return false; - } - - return true; - } - case FSCRYPT_POLICY_V2: { - const struct fscrypt_policy_v2 *policy = &policy_u->v2; - - if (!fscrypt_valid_enc_modes(policy->contents_encryption_mode, - policy->filenames_encryption_mode)) { - fscrypt_warn(inode, - "Unsupported encryption modes (contents %d, filenames %d)", - policy->contents_encryption_mode, - policy->filenames_encryption_mode); - return false; - } - - if (policy->flags & ~FSCRYPT_POLICY_FLAGS_VALID) { - fscrypt_warn(inode, - "Unsupported encryption flags (0x%02x)", - policy->flags); - return false; - } - - if ((policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) && - !supported_iv_ino_lblk_64_policy(policy, inode)) - return false; - - if (memchr_inv(policy->__reserved, 0, - sizeof(policy->__reserved))) { - fscrypt_warn(inode, - "Reserved bits set in encryption policy"); - return false; - } - - return true; - } + case FSCRYPT_POLICY_V1: + return fscrypt_supported_v1_policy(&policy_u->v1, inode); + case FSCRYPT_POLICY_V2: + return fscrypt_supported_v2_policy(&policy_u->v2, inode); } return false; } |