summaryrefslogtreecommitdiffstats
path: root/fs/crypto/keyinfo.c
diff options
context:
space:
mode:
Diffstat (limited to 'fs/crypto/keyinfo.c')
-rw-r--r--fs/crypto/keyinfo.c611
1 files changed, 0 insertions, 611 deletions
diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c
deleted file mode 100644
index 207ebed918c1..000000000000
--- a/fs/crypto/keyinfo.c
+++ /dev/null
@@ -1,611 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * key management facility for FS encryption support.
- *
- * Copyright (C) 2015, Google, Inc.
- *
- * This contains encryption key functions.
- *
- * Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015.
- */
-
-#include <keys/user-type.h>
-#include <linux/hashtable.h>
-#include <linux/scatterlist.h>
-#include <crypto/aes.h>
-#include <crypto/algapi.h>
-#include <crypto/sha.h>
-#include <crypto/skcipher.h>
-#include "fscrypt_private.h"
-
-static struct crypto_shash *essiv_hash_tfm;
-
-/* Table of keys referenced by FS_POLICY_FLAG_DIRECT_KEY policies */
-static DEFINE_HASHTABLE(fscrypt_master_keys, 6); /* 6 bits = 64 buckets */
-static DEFINE_SPINLOCK(fscrypt_master_keys_lock);
-
-/*
- * Key derivation function. This generates the derived key by encrypting the
- * master key with AES-128-ECB using the inode's nonce as the AES key.
- *
- * The master key must be at least as long as the derived key. If the master
- * key is longer, then only the first 'derived_keysize' bytes are used.
- */
-static int derive_key_aes(const u8 *master_key,
- const struct fscrypt_context *ctx,
- u8 *derived_key, unsigned int derived_keysize)
-{
- int res = 0;
- struct skcipher_request *req = NULL;
- DECLARE_CRYPTO_WAIT(wait);
- struct scatterlist src_sg, dst_sg;
- struct crypto_skcipher *tfm = crypto_alloc_skcipher("ecb(aes)", 0, 0);
-
- if (IS_ERR(tfm)) {
- res = PTR_ERR(tfm);
- tfm = NULL;
- goto out;
- }
- crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
- req = skcipher_request_alloc(tfm, GFP_NOFS);
- if (!req) {
- res = -ENOMEM;
- goto out;
- }
- skcipher_request_set_callback(req,
- CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
- crypto_req_done, &wait);
- res = crypto_skcipher_setkey(tfm, ctx->nonce, sizeof(ctx->nonce));
- if (res < 0)
- goto out;
-
- sg_init_one(&src_sg, master_key, derived_keysize);
- sg_init_one(&dst_sg, derived_key, derived_keysize);
- skcipher_request_set_crypt(req, &src_sg, &dst_sg, derived_keysize,
- NULL);
- res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
-out:
- skcipher_request_free(req);
- crypto_free_skcipher(tfm);
- return res;
-}
-
-/*
- * Search the current task's subscribed keyrings for a "logon" key with
- * description prefix:descriptor, and if found acquire a read lock on it and
- * return a pointer to its validated payload in *payload_ret.
- */
-static struct key *
-find_and_lock_process_key(const char *prefix,
- const u8 descriptor[FS_KEY_DESCRIPTOR_SIZE],
- unsigned int min_keysize,
- const struct fscrypt_key **payload_ret)
-{
- char *description;
- struct key *key;
- const struct user_key_payload *ukp;
- const struct fscrypt_key *payload;
-
- description = kasprintf(GFP_NOFS, "%s%*phN", prefix,
- FS_KEY_DESCRIPTOR_SIZE, descriptor);
- if (!description)
- return ERR_PTR(-ENOMEM);
-
- key = request_key(&key_type_logon, description, NULL);
- kfree(description);
- if (IS_ERR(key))
- return key;
-
- down_read(&key->sem);
- ukp = user_key_payload_locked(key);
-
- if (!ukp) /* was the key revoked before we acquired its semaphore? */
- goto invalid;
-
- payload = (const struct fscrypt_key *)ukp->data;
-
- if (ukp->datalen != sizeof(struct fscrypt_key) ||
- payload->size < 1 || payload->size > FS_MAX_KEY_SIZE) {
- fscrypt_warn(NULL,
- "key with description '%s' has invalid payload",
- key->description);
- goto invalid;
- }
-
- if (payload->size < min_keysize) {
- fscrypt_warn(NULL,
- "key with description '%s' is too short (got %u bytes, need %u+ bytes)",
- key->description, payload->size, min_keysize);
- goto invalid;
- }
-
- *payload_ret = payload;
- return key;
-
-invalid:
- up_read(&key->sem);
- key_put(key);
- return ERR_PTR(-ENOKEY);
-}
-
-static struct fscrypt_mode available_modes[] = {
- [FS_ENCRYPTION_MODE_AES_256_XTS] = {
- .friendly_name = "AES-256-XTS",
- .cipher_str = "xts(aes)",
- .keysize = 64,
- .ivsize = 16,
- },
- [FS_ENCRYPTION_MODE_AES_256_CTS] = {
- .friendly_name = "AES-256-CTS-CBC",
- .cipher_str = "cts(cbc(aes))",
- .keysize = 32,
- .ivsize = 16,
- },
- [FS_ENCRYPTION_MODE_AES_128_CBC] = {
- .friendly_name = "AES-128-CBC",
- .cipher_str = "cbc(aes)",
- .keysize = 16,
- .ivsize = 16,
- .needs_essiv = true,
- },
- [FS_ENCRYPTION_MODE_AES_128_CTS] = {
- .friendly_name = "AES-128-CTS-CBC",
- .cipher_str = "cts(cbc(aes))",
- .keysize = 16,
- .ivsize = 16,
- },
- [FS_ENCRYPTION_MODE_ADIANTUM] = {
- .friendly_name = "Adiantum",
- .cipher_str = "adiantum(xchacha12,aes)",
- .keysize = 32,
- .ivsize = 32,
- },
-};
-
-static struct fscrypt_mode *
-select_encryption_mode(const struct fscrypt_info *ci, const struct inode *inode)
-{
- if (!fscrypt_valid_enc_modes(ci->ci_data_mode, ci->ci_filename_mode)) {
- fscrypt_warn(inode->i_sb,
- "inode %lu uses unsupported encryption modes (contents mode %d, filenames mode %d)",
- inode->i_ino, ci->ci_data_mode,
- ci->ci_filename_mode);
- return ERR_PTR(-EINVAL);
- }
-
- if (S_ISREG(inode->i_mode))
- return &available_modes[ci->ci_data_mode];
-
- if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
- return &available_modes[ci->ci_filename_mode];
-
- 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));
- return ERR_PTR(-EINVAL);
-}
-
-/* Find the master key, then derive the inode's actual encryption key */
-static int find_and_derive_key(const struct inode *inode,
- const struct fscrypt_context *ctx,
- u8 *derived_key, const struct fscrypt_mode *mode)
-{
- struct key *key;
- const struct fscrypt_key *payload;
- int err;
-
- key = find_and_lock_process_key(FS_KEY_DESC_PREFIX,
- ctx->master_key_descriptor,
- mode->keysize, &payload);
- if (key == ERR_PTR(-ENOKEY) && inode->i_sb->s_cop->key_prefix) {
- key = find_and_lock_process_key(inode->i_sb->s_cop->key_prefix,
- ctx->master_key_descriptor,
- mode->keysize, &payload);
- }
- if (IS_ERR(key))
- return PTR_ERR(key);
-
- if (ctx->flags & FS_POLICY_FLAG_DIRECT_KEY) {
- if (mode->ivsize < offsetofend(union fscrypt_iv, nonce)) {
- fscrypt_warn(inode->i_sb,
- "direct key mode not allowed with %s",
- mode->friendly_name);
- err = -EINVAL;
- } else if (ctx->contents_encryption_mode !=
- ctx->filenames_encryption_mode) {
- fscrypt_warn(inode->i_sb,
- "direct key mode not allowed with different contents and filenames modes");
- err = -EINVAL;
- } else {
- memcpy(derived_key, payload->raw, mode->keysize);
- err = 0;
- }
- } else {
- err = derive_key_aes(payload->raw, ctx, derived_key,
- mode->keysize);
- }
- up_read(&key->sem);
- key_put(key);
- return err;
-}
-
-/* Allocate and key a symmetric cipher object for the given encryption mode */
-static struct crypto_skcipher *
-allocate_skcipher_for_mode(struct fscrypt_mode *mode, const u8 *raw_key,
- const struct inode *inode)
-{
- struct crypto_skcipher *tfm;
- int err;
-
- tfm = crypto_alloc_skcipher(mode->cipher_str, 0, 0);
- if (IS_ERR(tfm)) {
- fscrypt_warn(inode->i_sb,
- "error allocating '%s' transform for inode %lu: %ld",
- mode->cipher_str, inode->i_ino, PTR_ERR(tfm));
- return tfm;
- }
- if (unlikely(!mode->logged_impl_name)) {
- /*
- * fscrypt performance can vary greatly depending on which
- * crypto algorithm implementation is used. Help people debug
- * performance problems by logging the ->cra_driver_name the
- * first time a mode is used. Note that multiple threads can
- * race here, but it doesn't really matter.
- */
- mode->logged_impl_name = true;
- pr_info("fscrypt: %s using implementation \"%s\"\n",
- mode->friendly_name,
- crypto_skcipher_alg(tfm)->base.cra_driver_name);
- }
- crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
- err = crypto_skcipher_setkey(tfm, raw_key, mode->keysize);
- if (err)
- goto err_free_tfm;
-
- return tfm;
-
-err_free_tfm:
- crypto_free_skcipher(tfm);
- return ERR_PTR(err);
-}
-
-/* Master key referenced by FS_POLICY_FLAG_DIRECT_KEY policy */
-struct fscrypt_master_key {
- struct hlist_node mk_node;
- refcount_t mk_refcount;
- const struct fscrypt_mode *mk_mode;
- struct crypto_skcipher *mk_ctfm;
- u8 mk_descriptor[FS_KEY_DESCRIPTOR_SIZE];
- u8 mk_raw[FS_MAX_KEY_SIZE];
-};
-
-static void free_master_key(struct fscrypt_master_key *mk)
-{
- if (mk) {
- crypto_free_skcipher(mk->mk_ctfm);
- kzfree(mk);
- }
-}
-
-static void put_master_key(struct fscrypt_master_key *mk)
-{
- if (!refcount_dec_and_lock(&mk->mk_refcount, &fscrypt_master_keys_lock))
- return;
- hash_del(&mk->mk_node);
- spin_unlock(&fscrypt_master_keys_lock);
-
- free_master_key(mk);
-}
-
-/*
- * Find/insert the given master key into the fscrypt_master_keys table. If
- * found, it is returned with elevated refcount, and 'to_insert' is freed if
- * non-NULL. If not found, 'to_insert' is inserted and returned if it's
- * non-NULL; otherwise NULL is returned.
- */
-static struct fscrypt_master_key *
-find_or_insert_master_key(struct fscrypt_master_key *to_insert,
- const u8 *raw_key, const struct fscrypt_mode *mode,
- const struct fscrypt_info *ci)
-{
- unsigned long hash_key;
- struct fscrypt_master_key *mk;
-
- /*
- * Careful: to avoid potentially leaking secret key bytes via timing
- * information, we must key the hash table by descriptor rather than by
- * raw key, and use crypto_memneq() when comparing raw keys.
- */
-
- BUILD_BUG_ON(sizeof(hash_key) > FS_KEY_DESCRIPTOR_SIZE);
- memcpy(&hash_key, ci->ci_master_key_descriptor, sizeof(hash_key));
-
- spin_lock(&fscrypt_master_keys_lock);
- hash_for_each_possible(fscrypt_master_keys, mk, mk_node, hash_key) {
- if (memcmp(ci->ci_master_key_descriptor, mk->mk_descriptor,
- FS_KEY_DESCRIPTOR_SIZE) != 0)
- continue;
- if (mode != mk->mk_mode)
- continue;
- if (crypto_memneq(raw_key, mk->mk_raw, mode->keysize))
- continue;
- /* using existing tfm with same (descriptor, mode, raw_key) */
- refcount_inc(&mk->mk_refcount);
- spin_unlock(&fscrypt_master_keys_lock);
- free_master_key(to_insert);
- return mk;
- }
- if (to_insert)
- hash_add(fscrypt_master_keys, &to_insert->mk_node, hash_key);
- spin_unlock(&fscrypt_master_keys_lock);
- return to_insert;
-}
-
-/* Prepare to encrypt directly using the master key in the given mode */
-static struct fscrypt_master_key *
-fscrypt_get_master_key(const struct fscrypt_info *ci, struct fscrypt_mode *mode,
- const u8 *raw_key, const struct inode *inode)
-{
- struct fscrypt_master_key *mk;
- int err;
-
- /* Is there already a tfm for this key? */
- mk = find_or_insert_master_key(NULL, raw_key, mode, ci);
- if (mk)
- return mk;
-
- /* Nope, allocate one. */
- mk = kzalloc(sizeof(*mk), GFP_NOFS);
- if (!mk)
- return ERR_PTR(-ENOMEM);
- refcount_set(&mk->mk_refcount, 1);
- mk->mk_mode = mode;
- mk->mk_ctfm = allocate_skcipher_for_mode(mode, raw_key, inode);
- if (IS_ERR(mk->mk_ctfm)) {
- err = PTR_ERR(mk->mk_ctfm);
- mk->mk_ctfm = NULL;
- goto err_free_mk;
- }
- memcpy(mk->mk_descriptor, ci->ci_master_key_descriptor,
- FS_KEY_DESCRIPTOR_SIZE);
- memcpy(mk->mk_raw, raw_key, mode->keysize);
-
- return find_or_insert_master_key(mk, raw_key, mode, ci);
-
-err_free_mk:
- free_master_key(mk);
- return ERR_PTR(err);
-}
-
-static int derive_essiv_salt(const u8 *key, int keysize, u8 *salt)
-{
- struct crypto_shash *tfm = READ_ONCE(essiv_hash_tfm);
-
- /* init hash transform on demand */
- if (unlikely(!tfm)) {
- struct crypto_shash *prev_tfm;
-
- tfm = crypto_alloc_shash("sha256", 0, 0);
- if (IS_ERR(tfm)) {
- fscrypt_warn(NULL,
- "error allocating SHA-256 transform: %ld",
- PTR_ERR(tfm));
- return PTR_ERR(tfm);
- }
- prev_tfm = cmpxchg(&essiv_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, key, keysize, salt);
- }
-}
-
-static int init_essiv_generator(struct fscrypt_info *ci, const u8 *raw_key,
- int keysize)
-{
- int err;
- struct crypto_cipher *essiv_tfm;
- u8 salt[SHA256_DIGEST_SIZE];
-
- essiv_tfm = crypto_alloc_cipher("aes", 0, 0);
- if (IS_ERR(essiv_tfm))
- return PTR_ERR(essiv_tfm);
-
- ci->ci_essiv_tfm = essiv_tfm;
-
- err = derive_essiv_salt(raw_key, keysize, salt);
- if (err)
- goto out;
-
- /*
- * Using SHA256 to derive the salt/key will result in AES-256 being
- * used for IV generation. File contents encryption will still use the
- * configured keysize (AES-128) nevertheless.
- */
- err = crypto_cipher_setkey(essiv_tfm, salt, sizeof(salt));
- if (err)
- goto out;
-
-out:
- memzero_explicit(salt, sizeof(salt));
- return err;
-}
-
-void __exit fscrypt_essiv_cleanup(void)
-{
- crypto_free_shash(essiv_hash_tfm);
-}
-
-/*
- * Given the encryption mode and key (normally the derived key, but for
- * FS_POLICY_FLAG_DIRECT_KEY mode it's the master key), set up the inode's
- * symmetric cipher transform object(s).
- */
-static int setup_crypto_transform(struct fscrypt_info *ci,
- struct fscrypt_mode *mode,
- const u8 *raw_key, const struct inode *inode)
-{
- struct fscrypt_master_key *mk;
- struct crypto_skcipher *ctfm;
- int err;
-
- if (ci->ci_flags & FS_POLICY_FLAG_DIRECT_KEY) {
- mk = fscrypt_get_master_key(ci, mode, raw_key, inode);
- if (IS_ERR(mk))
- return PTR_ERR(mk);
- ctfm = mk->mk_ctfm;
- } else {
- mk = NULL;
- ctfm = allocate_skcipher_for_mode(mode, raw_key, inode);
- if (IS_ERR(ctfm))
- return PTR_ERR(ctfm);
- }
- ci->ci_master_key = mk;
- ci->ci_ctfm = ctfm;
-
- if (mode->needs_essiv) {
- /* ESSIV implies 16-byte IVs which implies !DIRECT_KEY */
- WARN_ON(mode->ivsize != AES_BLOCK_SIZE);
- WARN_ON(ci->ci_flags & FS_POLICY_FLAG_DIRECT_KEY);
-
- err = init_essiv_generator(ci, raw_key, mode->keysize);
- if (err) {
- fscrypt_warn(inode->i_sb,
- "error initializing ESSIV generator for inode %lu: %d",
- inode->i_ino, err);
- return err;
- }
- }
- return 0;
-}
-
-static void put_crypt_info(struct fscrypt_info *ci)
-{
- if (!ci)
- return;
-
- if (ci->ci_master_key) {
- put_master_key(ci->ci_master_key);
- } else {
- crypto_free_skcipher(ci->ci_ctfm);
- crypto_free_cipher(ci->ci_essiv_tfm);
- }
- kmem_cache_free(fscrypt_info_cachep, ci);
-}
-
-int fscrypt_get_encryption_info(struct inode *inode)
-{
- struct fscrypt_info *crypt_info;
- struct fscrypt_context ctx;
- struct fscrypt_mode *mode;
- u8 *raw_key = NULL;
- int res;
-
- if (fscrypt_has_encryption_key(inode))
- return 0;
-
- res = fscrypt_initialize(inode->i_sb->s_cop->flags);
- if (res)
- return res;
-
- res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
- if (res < 0) {
- if (!fscrypt_dummy_context_enabled(inode) ||
- IS_ENCRYPTED(inode))
- return res;
- /* Fake up a context for an unencrypted directory */
- memset(&ctx, 0, sizeof(ctx));
- ctx.format = FS_ENCRYPTION_CONTEXT_FORMAT_V1;
- ctx.contents_encryption_mode = FS_ENCRYPTION_MODE_AES_256_XTS;
- ctx.filenames_encryption_mode = FS_ENCRYPTION_MODE_AES_256_CTS;
- memset(ctx.master_key_descriptor, 0x42, FS_KEY_DESCRIPTOR_SIZE);
- } else if (res != sizeof(ctx)) {
- return -EINVAL;
- }
-
- if (ctx.format != FS_ENCRYPTION_CONTEXT_FORMAT_V1)
- return -EINVAL;
-
- if (ctx.flags & ~FS_POLICY_FLAGS_VALID)
- return -EINVAL;
-
- crypt_info = kmem_cache_zalloc(fscrypt_info_cachep, GFP_NOFS);
- if (!crypt_info)
- return -ENOMEM;
-
- crypt_info->ci_flags = ctx.flags;
- crypt_info->ci_data_mode = ctx.contents_encryption_mode;
- crypt_info->ci_filename_mode = ctx.filenames_encryption_mode;
- memcpy(crypt_info->ci_master_key_descriptor, ctx.master_key_descriptor,
- FS_KEY_DESCRIPTOR_SIZE);
- memcpy(crypt_info->ci_nonce, ctx.nonce, FS_KEY_DERIVATION_NONCE_SIZE);
-
- mode = select_encryption_mode(crypt_info, inode);
- if (IS_ERR(mode)) {
- res = PTR_ERR(mode);
- goto out;
- }
- WARN_ON(mode->ivsize > FSCRYPT_MAX_IV_SIZE);
- crypt_info->ci_mode = mode;
-
- /*
- * This cannot be a stack buffer because it may be passed to the
- * scatterlist crypto API as part of key derivation.
- */
- res = -ENOMEM;
- raw_key = kmalloc(mode->keysize, GFP_NOFS);
- if (!raw_key)
- goto out;
-
- res = find_and_derive_key(inode, &ctx, raw_key, mode);
- if (res)
- goto out;
-
- res = setup_crypto_transform(crypt_info, mode, raw_key, inode);
- if (res)
- goto out;
-
- if (cmpxchg_release(&inode->i_crypt_info, NULL, crypt_info) == NULL)
- crypt_info = NULL;
-out:
- if (res == -ENOKEY)
- res = 0;
- put_crypt_info(crypt_info);
- kzfree(raw_key);
- return res;
-}
-EXPORT_SYMBOL(fscrypt_get_encryption_info);
-
-/**
- * fscrypt_put_encryption_info - free most of an inode's fscrypt data
- *
- * Free the inode's fscrypt_info. Filesystems must call this when the inode is
- * being evicted. An RCU grace period need not have elapsed yet.
- */
-void fscrypt_put_encryption_info(struct inode *inode)
-{
- put_crypt_info(inode->i_crypt_info);
- inode->i_crypt_info = NULL;
-}
-EXPORT_SYMBOL(fscrypt_put_encryption_info);
-
-/**
- * fscrypt_free_inode - free an inode's fscrypt data requiring RCU delay
- *
- * Free the inode's cached decrypted symlink target, if any. Filesystems must
- * call this after an RCU grace period, just before they free the inode.
- */
-void fscrypt_free_inode(struct inode *inode)
-{
- if (IS_ENCRYPTED(inode) && S_ISLNK(inode->i_mode)) {
- kfree(inode->i_link);
- inode->i_link = NULL;
- }
-}
-EXPORT_SYMBOL(fscrypt_free_inode);