1 files changed, 272 insertions, 79 deletions

diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c
index 7874c9bb2fc5..1e11a683f63d 100644
--- a/fs/crypto/keyinfo.c
+++ b/fs/crypto/keyinfo.c
@@ -10,15 +10,21 @@
  */
 
 #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.
@@ -123,56 +129,37 @@ invalid:
 	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,
 	},
 };
 
@@ -198,14 +185,196 @@ select_encryption_mode(const struct fscrypt_info *ci, const struct inode *inode)
 	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)
@@ -275,11 +444,67 @@ 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 crypto_skcipher *ctfm;
 	struct fscrypt_mode *mode;
 	u8 *raw_key = NULL;
 	int res;
@@ -312,74 +537,42 @@ int fscrypt_get_encryption_info(struct inode *inode)
 	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: