Merge tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt

Pull fscrypt updates from Eric Biggers:
 "This release adds SM4 encryption support, contributed by Tianjia
  Zhang. SM4 is a Chinese block cipher that is an alternative to AES.

  I recommend against using SM4, but (according to Tianjia) some people
  are being required to use it. Since SM4 has been turning up in many
  other places (crypto API, wireless, TLS, OpenSSL, ARMv8 CPUs, etc.),
  it hasn't been very controversial, and some people have to use it, I
  don't think it would be fair for me to reject this optional feature.

  Besides the above, there are a couple cleanups"

* tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt:
  fscrypt: add additional documentation for SM4 support
  fscrypt: remove unused Speck definitions
  fscrypt: Add SM4 XTS/CTS symmetric algorithm support
  blk-crypto: Add support for SM4-XTS blk crypto mode
  fscrypt: add comment for fscrypt_valid_enc_modes_v1()
  fscrypt: pass super_block to fscrypt_put_master_key_activeref()

4 files changed, 38 insertions, 18 deletions

diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index d5f68a0c5d15..316a778cec0f 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -439,13 +439,7 @@ struct fscrypt_master_key_secret {
 struct fscrypt_master_key {
 
 	/*
-	 * Back-pointer to the super_block of the filesystem to which this
-	 * master key has been added.  Only valid if ->mk_active_refs > 0.
-	 */
-	struct super_block			*mk_sb;
-
-	/*
-	 * Link in ->mk_sb->s_master_keys->key_hashtable.
+	 * Link in ->s_master_keys->key_hashtable.
 	 * Only valid if ->mk_active_refs > 0.
 	 */
 	struct hlist_node			mk_node;
@@ -456,7 +450,7 @@ struct fscrypt_master_key {
 	/*
 	 * Active and structural reference counts.  An active ref guarantees
 	 * that the struct continues to exist, continues to be in the keyring
-	 * ->mk_sb->s_master_keys, and that any embedded subkeys (e.g.
+	 * ->s_master_keys, and that any embedded subkeys (e.g.
 	 * ->mk_direct_keys) that have been prepared continue to exist.
 	 * A structural ref only guarantees that the struct continues to exist.
 	 *
@@ -569,7 +563,8 @@ static inline int master_key_spec_len(const struct fscrypt_key_specifier *spec)
 
 void fscrypt_put_master_key(struct fscrypt_master_key *mk);
 
-void fscrypt_put_master_key_activeref(struct fscrypt_master_key *mk);
+void fscrypt_put_master_key_activeref(struct super_block *sb,
+				      struct fscrypt_master_key *mk);
 
 struct fscrypt_master_key *
 fscrypt_find_master_key(struct super_block *sb,
diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c
index 2a24b1f0ae68..78dd2ff306bd 100644
--- a/fs/crypto/keyring.c
+++ b/fs/crypto/keyring.c
@@ -79,10 +79,9 @@ void fscrypt_put_master_key(struct fscrypt_master_key *mk)
 	call_rcu(&mk->mk_rcu_head, fscrypt_free_master_key);
 }
 
-void fscrypt_put_master_key_activeref(struct fscrypt_master_key *mk)
+void fscrypt_put_master_key_activeref(struct super_block *sb,
+				      struct fscrypt_master_key *mk)
 {
-	struct super_block *sb = mk->mk_sb;
-	struct fscrypt_keyring *keyring = sb->s_master_keys;
 	size_t i;
 
 	if (!refcount_dec_and_test(&mk->mk_active_refs))
@@ -93,9 +92,9 @@ void fscrypt_put_master_key_activeref(struct fscrypt_master_key *mk)
 	 * destroying any subkeys embedded in it.
 	 */
 
-	spin_lock(&keyring->lock);
+	spin_lock(&sb->s_master_keys->lock);
 	hlist_del_rcu(&mk->mk_node);
-	spin_unlock(&keyring->lock);
+	spin_unlock(&sb->s_master_keys->lock);
 
 	/*
 	 * ->mk_active_refs == 0 implies that ->mk_secret is not present and
@@ -243,7 +242,7 @@ void fscrypt_destroy_keyring(struct super_block *sb)
 			WARN_ON(refcount_read(&mk->mk_struct_refs) != 1);
 			WARN_ON(!is_master_key_secret_present(&mk->mk_secret));
 			wipe_master_key_secret(&mk->mk_secret);
-			fscrypt_put_master_key_activeref(mk);
+			fscrypt_put_master_key_activeref(sb, mk);
 		}
 	}
 	kfree_sensitive(keyring);
@@ -424,7 +423,6 @@ static int add_new_master_key(struct super_block *sb,
 	if (!mk)
 		return -ENOMEM;
 
-	mk->mk_sb = sb;
 	init_rwsem(&mk->mk_sem);
 	refcount_set(&mk->mk_struct_refs, 1);
 	mk->mk_spec = *mk_spec;
@@ -1068,7 +1066,7 @@ static int do_remove_key(struct file *filp, void __user *_uarg, bool all_users)
 	err = -ENOKEY;
 	if (is_master_key_secret_present(&mk->mk_secret)) {
 		wipe_master_key_secret(&mk->mk_secret);
-		fscrypt_put_master_key_activeref(mk);
+		fscrypt_put_master_key_activeref(sb, mk);
 		err = 0;
 	}
 	inodes_remain = refcount_read(&mk->mk_active_refs) > 0;
diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
index f7407071a952..94757ccd3056 100644
--- a/fs/crypto/keysetup.c
+++ b/fs/crypto/keysetup.c
@@ -44,6 +44,21 @@ struct fscrypt_mode fscrypt_modes[] = {
 		.security_strength = 16,
 		.ivsize = 16,
 	},
+	[FSCRYPT_MODE_SM4_XTS] = {
+		.friendly_name = "SM4-XTS",
+		.cipher_str = "xts(sm4)",
+		.keysize = 32,
+		.security_strength = 16,
+		.ivsize = 16,
+		.blk_crypto_mode = BLK_ENCRYPTION_MODE_SM4_XTS,
+	},
+	[FSCRYPT_MODE_SM4_CTS] = {
+		.friendly_name = "SM4-CTS-CBC",
+		.cipher_str = "cts(cbc(sm4))",
+		.keysize = 16,
+		.security_strength = 16,
+		.ivsize = 16,
+	},
 	[FSCRYPT_MODE_ADIANTUM] = {
 		.friendly_name = "Adiantum",
 		.cipher_str = "adiantum(xchacha12,aes)",
@@ -509,7 +524,7 @@ static void put_crypt_info(struct fscrypt_info *ci)
 		spin_lock(&mk->mk_decrypted_inodes_lock);
 		list_del(&ci->ci_master_key_link);
 		spin_unlock(&mk->mk_decrypted_inodes_lock);
-		fscrypt_put_master_key_activeref(mk);
+		fscrypt_put_master_key_activeref(ci->ci_inode->i_sb, mk);
 	}
 	memzero_explicit(ci, sizeof(*ci));
 	kmem_cache_free(fscrypt_info_cachep, ci);
diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
index 46757c3052ef..893661b52376 100644
--- a/fs/crypto/policy.c
+++ b/fs/crypto/policy.c
@@ -61,6 +61,13 @@ fscrypt_get_dummy_policy(struct super_block *sb)
 	return sb->s_cop->get_dummy_policy(sb);
 }
 
+/*
+ * Return %true if the given combination of encryption modes is supported for v1
+ * (and later) encryption policies.
+ *
+ * Do *not* add anything new here, since v1 encryption policies are deprecated.
+ * New combinations of modes should go in fscrypt_valid_enc_modes_v2() only.
+ */
 static bool fscrypt_valid_enc_modes_v1(u32 contents_mode, u32 filenames_mode)
 {
 	if (contents_mode == FSCRYPT_MODE_AES_256_XTS &&
@@ -83,6 +90,11 @@ static bool fscrypt_valid_enc_modes_v2(u32 contents_mode, u32 filenames_mode)
 	if (contents_mode == FSCRYPT_MODE_AES_256_XTS &&
 	    filenames_mode == FSCRYPT_MODE_AES_256_HCTR2)
 		return true;
+
+	if (contents_mode == FSCRYPT_MODE_SM4_XTS &&
+	    filenames_mode == FSCRYPT_MODE_SM4_CTS)
+		return true;
+
 	return fscrypt_valid_enc_modes_v1(contents_mode, filenames_mode);
 }