linux-kernel - [PATCH 1/2] apparmor: Use shash crypto API interface for profile hashes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1380469162-18604-2-git-send-email-john.johansen@canonical.com>
Date:	Sun, 29 Sep 2013 08:39:21 -0700
From:	John Johansen <john.johansen@...onical.com>
To:	jmorris@...ei.org
Cc:	linux-kernel@...r.kernel.org, Tyler Hicks <tyhicks@...onical.com>
Subject: [PATCH 1/2] apparmor: Use shash crypto API interface for profile hashes

From: Tyler Hicks <tyhicks@...onical.com>

Use the shash interface, rather than the hash interface, when hashing
AppArmor profiles. The shash interface does not use scatterlists and it
is a better fit for what AppArmor needs.

This fixes a kernel paging BUG when aa_calc_profile_hash() is passed a
buffer from vmalloc(). The hash interface requires callers to handle
vmalloc() buffers differently than what AppArmor was doing. Due to
vmalloc() memory not being physically contiguous, each individual page
behind the buffer must be assigned to a scatterlist with sg_set_page()
and then the scatterlist passed to crypto_hash_update().

The shash interface does not have that limitation and allows vmalloc()
and kmalloc() buffers to be handled in the same manner.

BugLink: https://launchpad.net/bugs/1216294/
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=62261

Signed-off-by: Tyler Hicks <tyhicks@...onical.com>
Acked-by: Seth Arnold <seth.arnold@...onical.com>
Signed-off-by: John Johansen <john.johansen@...onical.com>
---
 security/apparmor/crypto.c | 34 ++++++++++++++++------------------
 1 file changed, 16 insertions(+), 18 deletions(-)

diff --git a/security/apparmor/crypto.c b/security/apparmor/crypto.c
index d6222ba..532471d 100644
--- a/security/apparmor/crypto.c
+++ b/security/apparmor/crypto.c
@@ -15,14 +15,14 @@
  * it should be.
  */
 
-#include <linux/crypto.h>
+#include <crypto/hash.h>
 
 #include "include/apparmor.h"
 #include "include/crypto.h"
 
 static unsigned int apparmor_hash_size;
 
-static struct crypto_hash *apparmor_tfm;
+static struct crypto_shash *apparmor_tfm;
 
 unsigned int aa_hash_size(void)
 {
@@ -32,35 +32,33 @@ unsigned int aa_hash_size(void)
 int aa_calc_profile_hash(struct aa_profile *profile, u32 version, void *start,
 			 size_t len)
 {
-	struct scatterlist sg[2];
-	struct hash_desc desc = {
-		.tfm = apparmor_tfm,
-		.flags = 0
-	};
+	struct {
+		struct shash_desc shash;
+		char ctx[crypto_shash_descsize(apparmor_tfm)];
+	} desc;
 	int error = -ENOMEM;
 	u32 le32_version = cpu_to_le32(version);
 
 	if (!apparmor_tfm)
 		return 0;
 
-	sg_init_table(sg, 2);
-	sg_set_buf(&sg[0], &le32_version, 4);
-	sg_set_buf(&sg[1], (u8 *) start, len);
-
 	profile->hash = kzalloc(apparmor_hash_size, GFP_KERNEL);
 	if (!profile->hash)
 		goto fail;
 
-	error = crypto_hash_init(&desc);
+	desc.shash.tfm = apparmor_tfm;
+	desc.shash.flags = 0;
+
+	error = crypto_shash_init(&desc.shash);
 	if (error)
 		goto fail;
-	error = crypto_hash_update(&desc, &sg[0], 4);
+	error = crypto_shash_update(&desc.shash, (u8 *) &le32_version, 4);
 	if (error)
 		goto fail;
-	error = crypto_hash_update(&desc, &sg[1], len);
+	error = crypto_shash_update(&desc.shash, (u8 *) start, len);
 	if (error)
 		goto fail;
-	error = crypto_hash_final(&desc, profile->hash);
+	error = crypto_shash_final(&desc.shash, profile->hash);
 	if (error)
 		goto fail;
 
@@ -75,19 +73,19 @@ fail:
 
 static int __init init_profile_hash(void)
 {
-	struct crypto_hash *tfm;
+	struct crypto_shash *tfm;
 
 	if (!apparmor_initialized)
 		return 0;
 
-	tfm = crypto_alloc_hash("sha1", 0, CRYPTO_ALG_ASYNC);
+	tfm = crypto_alloc_shash("sha1", 0, CRYPTO_ALG_ASYNC);
 	if (IS_ERR(tfm)) {
 		int error = PTR_ERR(tfm);
 		AA_ERROR("failed to setup profile sha1 hashing: %d\n", error);
 		return error;
 	}
 	apparmor_tfm = tfm;
-	apparmor_hash_size = crypto_hash_digestsize(apparmor_tfm);
+	apparmor_hash_size = crypto_shash_digestsize(apparmor_tfm);
 
 	aa_info_message("AppArmor sha1 policy hashing enabled");
 
-- 
1.8.3.2

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/