Patch "KEYS: Sort out big_key initialisation" has been added to the 4.8-stable tree

Patch "KEYS: Sort out big_key initialisation" has been added to the 4.8-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    KEYS: Sort out big_key initialisation

to the 4.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     keys-sort-out-big_key-initialisation.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 7df3e59c3d1df4f87fe874c7956ef7a3d2f4d5fb Mon Sep 17 00:00:00 2001
From: David Howells <dhowells@redhat.com>
Date: Wed, 26 Oct 2016 15:02:01 +0100
Subject: KEYS: Sort out big_key initialisation

From: David Howells <dhowells@redhat.com>

commit 7df3e59c3d1df4f87fe874c7956ef7a3d2f4d5fb upstream.

big_key has two separate initialisation functions, one that registers the
key type and one that registers the crypto.  If the key type fails to
register, there's no problem if the crypto registers successfully because
there's no way to reach the crypto except through the key type.

However, if the key type registers successfully but the crypto does not,
big_key_rng and big_key_blkcipher may end up set to NULL - but the code
neither checks for this nor unregisters the big key key type.

Furthermore, since the key type is registered before the crypto, it is
theoretically possible for the kernel to try adding a big_key before the
crypto is set up, leading to the same effect.

Fix this by merging big_key_crypto_init() and big_key_init() and calling
the resulting function late.  If they're going to be encrypted, we
shouldn't be creating big_keys before we have the facilities to do the
encryption available.  The key type registration is also moved after the
crypto initialisation.

The fix also includes message printing on failure.

If the big_key type isn't correctly set up, simply doing:

	dd if=/dev/zero bs=4096 count=1 | keyctl padd big_key a @s

ought to cause an oops.

Fixes: 13100a72f40f5748a04017e0ab3df4cf27c809ef ('Security: Keys: Big keys stored encrypted')
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Peter Hlavaty <zer0mem@yahoo.com>
cc: Kirill Marinushkin <k.marinushkin@gmail.com>
cc: Artem Savkov <asavkov@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 security/keys/big_key.c |   59 ++++++++++++++++++++++++++----------------------
 1 file changed, 32 insertions(+), 27 deletions(-)

--- a/security/keys/big_key.c
+++ b/security/keys/big_key.c
@@ -9,6 +9,7 @@
  * 2 of the Licence, or (at your option) any later version.
  */
 
+#define pr_fmt(fmt) "big_key: "fmt
 #include <linux/init.h>
 #include <linux/seq_file.h>
 #include <linux/file.h>
@@ -341,44 +342,48 @@ error:
  */
 static int __init big_key_init(void)
 {
-	return register_key_type(&key_type_big_key);
-}
-
-/*
- * Initialize big_key crypto and RNG algorithms
- */
-static int __init big_key_crypto_init(void)
-{
-	int ret = -EINVAL;
+	struct crypto_skcipher *cipher;
+	struct crypto_rng *rng;
+	int ret;
 
-	/* init RNG */
-	big_key_rng = crypto_alloc_rng(big_key_rng_name, 0, 0);
-	if (IS_ERR(big_key_rng)) {
-		big_key_rng = NULL;
-		return -EFAULT;
+	rng = crypto_alloc_rng(big_key_rng_name, 0, 0);
+	if (IS_ERR(rng)) {
+		pr_err("Can't alloc rng: %ld\n", PTR_ERR(rng));
+		return PTR_ERR(rng);
 	}
 
+	big_key_rng = rng;
+
 	/* seed RNG */
-	ret = crypto_rng_reset(big_key_rng, NULL, crypto_rng_seedsize(big_key_rng));
-	if (ret)
-		goto error;
+	ret = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
+	if (ret) {
+		pr_err("Can't reset rng: %d\n", ret);
+		goto error_rng;
+	}
 
 	/* init block cipher */
-	big_key_skcipher = crypto_alloc_skcipher(big_key_alg_name,
-						 0, CRYPTO_ALG_ASYNC);
-	if (IS_ERR(big_key_skcipher)) {
-		big_key_skcipher = NULL;
-		ret = -EFAULT;
-		goto error;
+	cipher = crypto_alloc_skcipher(big_key_alg_name, 0, CRYPTO_ALG_ASYNC);
+	if (IS_ERR(cipher)) {
+		ret = PTR_ERR(cipher);
+		pr_err("Can't alloc crypto: %d\n", ret);
+		goto error_rng;
+	}
+
+	big_key_skcipher = cipher;
+
+	ret = register_key_type(&key_type_big_key);
+	if (ret < 0) {
+		pr_err("Can't register type: %d\n", ret);
+		goto error_cipher;
 	}
 
 	return 0;
 
-error:
+error_cipher:
+	crypto_free_skcipher(big_key_skcipher);
+error_rng:
 	crypto_free_rng(big_key_rng);
-	big_key_rng = NULL;
 	return ret;
 }
 
-device_initcall(big_key_init);
-late_initcall(big_key_crypto_init);
+late_initcall(big_key_init);


Patches currently in stable-queue which might be from dhowells@redhat.com are

queue-4.8/keys-fix-short-sprintf-buffer-in-proc-keys-show-function.patch
queue-4.8/security-keys-make-big_keys-dependent-on-stdrng.patch
queue-4.8/keys-sort-out-big_key-initialisation.patch