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FAILED: patch "[PATCH] crypto: gcm - fix incompatibility between "gcm" and" failed to apply to 4.9-stable tree

PATCH [email protected] 2 participants 3 messages May 17, 2019 – May 18, 2019

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[email protected]

author maintainer
#0 lore raw

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f699594d436960160f6d5ba84ed4a222f20d11cd Mon Sep 17 00:00:00 2001
From: Eric Biggers <[email protected]>
Date: Thu, 18 Apr 2019 14:43:02 -0700
Subject: [PATCH] crypto: gcm - fix incompatibility between "gcm" and
"gcm_base"

GCM instances can be created by either the "gcm" template, which only allows choosing the block cipher, e.g. "gcm(aes)"; or by "gcm_base", which allows choosing the ctr and ghash implementations, e.g. "gcm_base(ctr(aes-generic),ghash-generic)".

However, a "gcm_base" instance prevents a "gcm" instance from being registered using the same implementations. Nor will the instance be found by lookups of "gcm". This can be used as a denial of service. Moreover, "gcm_base" instances are never tested by the crypto self-tests, even if there are compatible "gcm" tests.

The root cause of these problems is that instances of the two templates use different cra_names. Therefore, fix these problems by making "gcm_base" instances set the same cra_name as "gcm" instances, e.g. "gcm(aes)" instead of "gcm_base(ctr(aes-generic),ghash-generic)".

This requires extracting the block cipher name from the name of the ctr algorithm. It also requires starting to verify that the algorithms are really ctr and ghash, not something else entirely. But it would be bizarre if anyone were actually using non-gcm-compatible algorithms with gcm_base, so this shouldn't break anyone in practice.

Fixes d00aa19b507b ("[CRYPTO] gcm: Allow block cipher parameter")
Cc [email protected]
Signed-off-by Eric Biggers <[email protected]>
Signed-off-by Herbert Xu <[email protected]>
crypto/gcm.c +11 -23
index ff498411b43f..33f45a980967 100644
@@ -597,7 +597,6 @@ static void crypto_gcm_free(struct aead_instance *inst)
 
 static int crypto_gcm_create_common(struct crypto_template *tmpl,
 				    struct rtattr **tb,
-				    const char *full_name,
 				    const char *ctr_name,
 				    const char *ghash_name)
 {

@@ -638,7 +637,8 @@ static int crypto_gcm_create_common(struct crypto_template *tmpl,
 		goto err_free_inst;
 
 	err = -EINVAL;
-	if (ghash->digestsize != 16)
+	if (strcmp(ghash->base.cra_name, "ghash") != 0 ||
+	    ghash->digestsize != 16)
 		goto err_drop_ghash;
 
 	crypto_set_skcipher_spawn(&ctx->ctr, aead_crypto_instance(inst));

@@ -650,24 +650,24 @@ static int crypto_gcm_create_common(struct crypto_template *tmpl,
 
 	ctr = crypto_spawn_skcipher_alg(&ctx->ctr);
 
-	/* We only support 16-byte blocks. */
+	/* The skcipher algorithm must be CTR mode, using 16-byte blocks. */
 	err = -EINVAL;
-	if (crypto_skcipher_alg_ivsize(ctr) != 16)
+	if (strncmp(ctr->base.cra_name, "ctr(", 4) != 0 ||
+	    crypto_skcipher_alg_ivsize(ctr) != 16 ||
+	    ctr->base.cra_blocksize != 1)
 		goto out_put_ctr;
 
-	/* Not a stream cipher? */
-	if (ctr->base.cra_blocksize != 1)
+	err = -ENAMETOOLONG;
+	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
+		     "gcm(%s", ctr->base.cra_name + 4) >= CRYPTO_MAX_ALG_NAME)
 		goto out_put_ctr;
 
-	err = -ENAMETOOLONG;
 	if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 		     "gcm_base(%s,%s)", ctr->base.cra_driver_name,
 		     ghash_alg->cra_driver_name) >=
 	    CRYPTO_MAX_ALG_NAME)
 		goto out_put_ctr;
 
-	memcpy(inst->alg.base.cra_name, full_name, CRYPTO_MAX_ALG_NAME);
-
 	inst->alg.base.cra_flags = (ghash->base.cra_flags |
 				    ctr->base.cra_flags) & CRYPTO_ALG_ASYNC;
 	inst->alg.base.cra_priority = (ghash->base.cra_priority +

@@ -709,7 +709,6 @@ static int crypto_gcm_create(struct crypto_template *tmpl, struct rtattr **tb)
 {
 	const char *cipher_name;
 	char ctr_name[CRYPTO_MAX_ALG_NAME];
-	char full_name[CRYPTO_MAX_ALG_NAME];
 
 	cipher_name = crypto_attr_alg_name(tb[1]);
 	if (IS_ERR(cipher_name))

@@ -719,12 +718,7 @@ static int crypto_gcm_create(struct crypto_template *tmpl, struct rtattr **tb)
 	    CRYPTO_MAX_ALG_NAME)
 		return -ENAMETOOLONG;
 
-	if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "gcm(%s)", cipher_name) >=
-	    CRYPTO_MAX_ALG_NAME)
-		return -ENAMETOOLONG;
-
-	return crypto_gcm_create_common(tmpl, tb, full_name,
-					ctr_name, "ghash");
+	return crypto_gcm_create_common(tmpl, tb, ctr_name, "ghash");
 }
 
 static int crypto_gcm_base_create(struct crypto_template *tmpl,

@@ -732,7 +726,6 @@ static int crypto_gcm_base_create(struct crypto_template *tmpl,
 {
 	const char *ctr_name;
 	const char *ghash_name;
-	char full_name[CRYPTO_MAX_ALG_NAME];
 
 	ctr_name = crypto_attr_alg_name(tb[1]);
 	if (IS_ERR(ctr_name))

@@ -742,12 +735,7 @@ static int crypto_gcm_base_create(struct crypto_template *tmpl,
 	if (IS_ERR(ghash_name))
 		return PTR_ERR(ghash_name);
 
-	if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "gcm_base(%s,%s)",
-		     ctr_name, ghash_name) >= CRYPTO_MAX_ALG_NAME)
-		return -ENAMETOOLONG;
-
-	return crypto_gcm_create_common(tmpl, tb, full_name,
-					ctr_name, ghash_name);
+	return crypto_gcm_create_common(tmpl, tb, ctr_name, ghash_name);
 }
 
 static int crypto_rfc4106_setkey(struct crypto_aead *parent, const u8 *key,
#1 lore raw
Quoted 10 lines · On Fri, May 17, 2019 at 02:37:18PM +0200, [email protected] wrote:

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

Quoted 8 lines

------------------ original commit in Linus's tree ------------------

From f699594d436960160f6d5ba84ed4a222f20d11cd Mon Sep 17 00:00:00 2001
From: Eric Biggers <[email protected]>
Date: Thu, 18 Apr 2019 14:43:02 -0700
Subject: [PATCH] crypto: gcm - fix incompatibility between "gcm" and
"gcm_base"

Can you apply the following commit first? Then this one applies cleanly:

	commit 9b40f79c08e81234d759f188b233980d7e81df6c
	Author: Wei Yongjun <[email protected]>
	Date:   Mon Oct 17 15:10:06 2016 +0000

	    crypto: gcm - Fix error return code in crypto_gcm_create_common()

- Eric

author maintainer
#2 lore raw
Quoted 20 lines · Eric Biggers
Quoted 10 lines · On Fri, May 17, 2019 at 02:37:18PM +0200, [email protected] wrote:

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

Quoted 8 lines

------------------ original commit in Linus's tree ------------------

From f699594d436960160f6d5ba84ed4a222f20d11cd Mon Sep 17 00:00:00 2001
From: Eric Biggers <[email protected]>
Date: Thu, 18 Apr 2019 14:43:02 -0700
Subject: [PATCH] crypto: gcm - fix incompatibility between "gcm" and
"gcm_base"

Quoted 7 lines

Can you apply the following commit first? Then this one applies cleanly:

	commit 9b40f79c08e81234d759f188b233980d7e81df6c
	Author: Wei Yongjun <[email protected]>
	Date:   Mon Oct 17 15:10:06 2016 +0000

	    crypto: gcm - Fix error return code in crypto_gcm_create_common()

Thank you, that worked!

greg k-h