*/
#include <keys/user-type.h>
+#include <linux/hashtable.h>
#include <linux/scatterlist.h>
#include <linux/ratelimit.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.
return ERR_PTR(-ENOKEY);
}
-/* 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, unsigned int derived_keysize)
-{
- struct key *key;
- const struct fscrypt_key *payload;
- int err;
-
- key = find_and_lock_process_key(FS_KEY_DESC_PREFIX,
- ctx->master_key_descriptor,
- derived_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,
- derived_keysize, &payload);
- }
- if (IS_ERR(key))
- return PTR_ERR(key);
- err = derive_key_aes(payload->raw, ctx, derived_key, derived_keysize);
- up_read(&key->sem);
- key_put(key);
- return err;
-}
-
-static struct fscrypt_mode {
- const char *friendly_name;
- const char *cipher_str;
- int keysize;
- bool logged_impl_name;
-} available_modes[] = {
+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,
},
};
return ERR_PTR(-EINVAL);
}
-static void put_crypt_info(struct fscrypt_info *ci)
+/* 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)
{
- if (!ci)
+ 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_WEAK_KEY);
+ 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);
- crypto_free_skcipher(ci->ci_ctfm);
- crypto_free_cipher(ci->ci_essiv_tfm);
- kmem_cache_free(fscrypt_info_cachep, ci);
+ 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)
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 crypto_skcipher *ctfm;
struct fscrypt_mode *mode;
u8 *raw_key = NULL;
int res;
if (ctx.flags & ~FS_POLICY_FLAGS_VALID)
return -EINVAL;
- crypt_info = kmem_cache_alloc(fscrypt_info_cachep, GFP_NOFS);
+ 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;
- crypt_info->ci_ctfm = NULL;
- crypt_info->ci_essiv_tfm = NULL;
- memcpy(crypt_info->ci_master_key, ctx.master_key_descriptor,
- sizeof(crypt_info->ci_master_key));
+ 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 is passed to the scatterlist
- * crypto API as part of key derivation.
+ * 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->keysize);
+ res = find_and_derive_key(inode, &ctx, raw_key, mode);
if (res)
goto out;
- ctfm = crypto_alloc_skcipher(mode->cipher_str, 0, 0);
- if (IS_ERR(ctfm)) {
- res = PTR_ERR(ctfm);
- fscrypt_warn(inode->i_sb,
- "error allocating '%s' transform for inode %lu: %d",
- mode->cipher_str, inode->i_ino, res);
- goto out;
- }
- 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(ctfm)->base.cra_driver_name);
- }
- crypt_info->ci_ctfm = ctfm;
- crypto_skcipher_set_flags(ctfm, CRYPTO_TFM_REQ_WEAK_KEY);
- res = crypto_skcipher_setkey(ctfm, raw_key, mode->keysize);
+ res = setup_crypto_transform(crypt_info, mode, raw_key, inode);
if (res)
goto out;
- if (S_ISREG(inode->i_mode) &&
- crypt_info->ci_data_mode == FS_ENCRYPTION_MODE_AES_128_CBC) {
- res = init_essiv_generator(crypt_info, raw_key, mode->keysize);
- if (res) {
- fscrypt_warn(inode->i_sb,
- "error initializing ESSIV generator for inode %lu: %d",
- inode->i_ino, res);
- goto out;
- }
- }
if (cmpxchg(&inode->i_crypt_info, NULL, crypt_info) == NULL)
crypt_info = NULL;
out:
projects / linux-2.6-microblaze.git / blobdiff