[PATCH 4/5] ext4 crypto: replace some BUG_ON()'s with error checks

["Theodore Ts'o" <tytso@xxxxxxx>]

Buggy (or hostile) userspace should not be able to cause the kernel to
crash.

Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
 fs/ext4/crypto.c        |  1 -
 fs/ext4/crypto_fname.c  |  2 --
 fs/ext4/crypto_key.c    | 16 +++++++++++++---
 fs/ext4/crypto_policy.c |  3 ++-
 4 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
index 3a5a7a2..879cb15 100644
--- a/fs/ext4/crypto.c
+++ b/fs/ext4/crypto.c
@@ -295,7 +295,6 @@ static int ext4_page_crypto(struct inode *inode,
 	else
 		res = crypto_ablkcipher_encrypt(req);
 	if (res == -EINPROGRESS || res == -EBUSY) {
-		BUG_ON(req->base.data != &ecr);
 		wait_for_completion(&ecr.completion);
 		res = ecr.res;
 	}
diff --git a/fs/ext4/crypto_fname.c b/fs/ext4/crypto_fname.c
index 847f919..2fbef8a 100644
--- a/fs/ext4/crypto_fname.c
+++ b/fs/ext4/crypto_fname.c
@@ -120,7 +120,6 @@ static int ext4_fname_encrypt(struct inode *inode,
 	ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, ciphertext_len, iv);
 	res = crypto_ablkcipher_encrypt(req);
 	if (res == -EINPROGRESS || res == -EBUSY) {
-		BUG_ON(req->base.data != &ecr);
 		wait_for_completion(&ecr.completion);
 		res = ecr.res;
 	}
@@ -182,7 +181,6 @@ static int ext4_fname_decrypt(struct inode *inode,
 	ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, iv);
 	res = crypto_ablkcipher_decrypt(req);
 	if (res == -EINPROGRESS || res == -EBUSY) {
-		BUG_ON(req->base.data != &ecr);
 		wait_for_completion(&ecr.completion);
 		res = ecr.res;
 	}
diff --git a/fs/ext4/crypto_key.c b/fs/ext4/crypto_key.c
index 1d510c1..f9270ec 100644
--- a/fs/ext4/crypto_key.c
+++ b/fs/ext4/crypto_key.c
@@ -71,7 +71,6 @@ static int ext4_derive_key_aes(char deriving_key[EXT4_AES_128_ECB_KEY_SIZE],
 				     EXT4_AES_256_XTS_KEY_SIZE, NULL);
 	res = crypto_ablkcipher_encrypt(req);
 	if (res == -EINPROGRESS || res == -EBUSY) {
-		BUG_ON(req->base.data != &ecr);
 		wait_for_completion(&ecr.completion);
 		res = ecr.res;
 	}
@@ -208,7 +207,12 @@ retry:
 		goto out;
 	}
 	crypt_info->ci_keyring_key = keyring_key;
-	BUG_ON(keyring_key->type != &key_type_logon);
+	if (keyring_key->type != &key_type_logon) {
+		printk_once(KERN_WARNING
+			    "ext4: key type must be logon\n");
+		res = -ENOKEY;
+		goto out;
+	}
 	ukp = ((struct user_key_payload *)keyring_key->payload.data);
 	if (ukp->datalen != sizeof(struct ext4_encryption_key)) {
 		res = -EINVAL;
@@ -217,7 +221,13 @@ retry:
 	master_key = (struct ext4_encryption_key *)ukp->data;
 	BUILD_BUG_ON(EXT4_AES_128_ECB_KEY_SIZE !=
 		     EXT4_KEY_DERIVATION_NONCE_SIZE);
-	BUG_ON(master_key->size != EXT4_AES_256_XTS_KEY_SIZE);
+	if (master_key->size != EXT4_AES_256_XTS_KEY_SIZE) {
+		printk_once(KERN_WARNING
+			    "ext4: key size incorrect: %d\n",
+			    master_key->size);
+		res = -ENOKEY;
+		goto out;
+	}
 	res = ext4_derive_key_aes(ctx.nonce, master_key->raw,
 				  raw_key);
 	if (res)
diff --git a/fs/ext4/crypto_policy.c b/fs/ext4/crypto_policy.c
index a640ec2..ad05069 100644
--- a/fs/ext4/crypto_policy.c
+++ b/fs/ext4/crypto_policy.c
@@ -150,7 +150,8 @@ int ext4_is_child_context_consistent_with_parent(struct inode *parent,
 
 	if ((parent == NULL) || (child == NULL)) {
 		pr_err("parent %p child %p\n", parent, child);
-		BUG_ON(1);
+		WARN_ON(1);	/* Should never happen */
+		return 0;
 	}
 	/* no restrictions if the parent directory is not encrypted */
 	if (!ext4_encrypted_inode(parent))
-- 
2.5.0

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