1 files changed, 40 insertions, 9 deletions

diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
index 5f858cee1e3b..80b8ca0f340b 100644
--- a/fs/crypto/policy.c
+++ b/fs/crypto/policy.c
@@ -61,7 +61,7 @@ fscrypt_get_dummy_policy(struct super_block *sb)
 	return sb->s_cop->get_dummy_policy(sb);
 }
 
-static bool fscrypt_valid_enc_modes(u32 contents_mode, u32 filenames_mode)
+static bool fscrypt_valid_enc_modes_v1(u32 contents_mode, u32 filenames_mode)
 {
 	if (contents_mode == FSCRYPT_MODE_AES_256_XTS &&
 	    filenames_mode == FSCRYPT_MODE_AES_256_CTS)
@@ -78,6 +78,14 @@ static bool fscrypt_valid_enc_modes(u32 contents_mode, u32 filenames_mode)
 	return false;
 }
 
+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;
+	return fscrypt_valid_enc_modes_v1(contents_mode, filenames_mode);
+}
+
 static bool supported_direct_key_modes(const struct inode *inode,
 				       u32 contents_mode, u32 filenames_mode)
 {
@@ -151,7 +159,7 @@ static bool supported_iv_ino_lblk_policy(const struct fscrypt_policy_v2 *policy,
 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,
+	if (!fscrypt_valid_enc_modes_v1(policy->contents_encryption_mode,
 				     policy->filenames_encryption_mode)) {
 		fscrypt_warn(inode,
 			     "Unsupported encryption modes (contents %d, filenames %d)",
@@ -187,7 +195,7 @@ static bool fscrypt_supported_v2_policy(const struct fscrypt_policy_v2 *policy,
 {
 	int count = 0;
 
-	if (!fscrypt_valid_enc_modes(policy->contents_encryption_mode,
+	if (!fscrypt_valid_enc_modes_v2(policy->contents_encryption_mode,
 				     policy->filenames_encryption_mode)) {
 		fscrypt_warn(inode,
 			     "Unsupported encryption modes (contents %d, filenames %d)",
@@ -686,6 +694,32 @@ const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir)
 }
 
 /**
+ * fscrypt_context_for_new_inode() - create an encryption context for a new inode
+ * @ctx: where context should be written
+ * @inode: inode from which to fetch policy and nonce
+ *
+ * Given an in-core "prepared" (via fscrypt_prepare_new_inode) inode,
+ * generate a new context and write it to ctx. ctx _must_ be at least
+ * FSCRYPT_SET_CONTEXT_MAX_SIZE bytes.
+ *
+ * Return: size of the resulting context or a negative error code.
+ */
+int fscrypt_context_for_new_inode(void *ctx, struct inode *inode)
+{
+	struct fscrypt_info *ci = inode->i_crypt_info;
+
+	BUILD_BUG_ON(sizeof(union fscrypt_context) !=
+			FSCRYPT_SET_CONTEXT_MAX_SIZE);
+
+	/* fscrypt_prepare_new_inode() should have set up the key already. */
+	if (WARN_ON_ONCE(!ci))
+		return -ENOKEY;
+
+	return fscrypt_new_context(ctx, &ci->ci_policy, ci->ci_nonce);
+}
+EXPORT_SYMBOL_GPL(fscrypt_context_for_new_inode);
+
+/**
  * fscrypt_set_context() - Set the fscrypt context of a new inode
  * @inode: a new inode
  * @fs_data: private data given by FS and passed to ->set_context()
@@ -701,12 +735,9 @@ int fscrypt_set_context(struct inode *inode, void *fs_data)
 	union fscrypt_context ctx;
 	int ctxsize;
 
-	/* fscrypt_prepare_new_inode() should have set up the key already. */
-	if (WARN_ON_ONCE(!ci))
-		return -ENOKEY;
-
-	BUILD_BUG_ON(sizeof(ctx) != FSCRYPT_SET_CONTEXT_MAX_SIZE);
-	ctxsize = fscrypt_new_context(&ctx, &ci->ci_policy, ci->ci_nonce);
+	ctxsize = fscrypt_context_for_new_inode(&ctx, inode);
+	if (ctxsize < 0)
+		return ctxsize;
 
 	/*
 	 * This may be the first time the inode number is available, so do any