crypto: pcrypt - Avoid deadlock by using per-instance padata queues

If the pcrypt template is used multiple times in an algorithm, then a
deadlock occurs because all pcrypt instances share the same
padata_instance, which completes requests in the order submitted.  That
is, the inner pcrypt request waits for the outer pcrypt request while
the outer request is already waiting for the inner.

This patch fixes this by allocating a set of queues for each pcrypt
instance instead of using two global queues.  In order to maintain
the existing user-space interface, the pinst structure remains global
so any sysfs modifications will apply to every pcrypt instance.

Note that when an update occurs we have to allocate memory for
every pcrypt instance.  Should one of the allocations fail we
will abort the update without rolling back changes already made.

The new per-instance data structure is called padata_shell and is
essentially a wrapper around parallel_data.

Reproducer:

	#include <linux/if_alg.h>
	#include <sys/socket.h>
	#include <unistd.h>

	int main()
	{
		struct sockaddr_alg addr = {
			.salg_type = "aead",
			.salg_name = "pcrypt(pcrypt(rfc4106-gcm-aesni))"
		};
		int algfd, reqfd;
		char buf[32] = { 0 };

		algfd = socket(AF_ALG, SOCK_SEQPACKET, 0);
		bind(algfd, (void *)&addr, sizeof(addr));
		setsockopt(algfd, SOL_ALG, ALG_SET_KEY, buf, 20);
		reqfd = accept(algfd, 0, 0);
		write(reqfd, buf, 32);
		read(reqfd, buf, 16);
	}

Reported-by: syzbot+56c7151cad94eec37c521f0e47d2eee53f9361c4@syzkaller.appspotmail.com
Fixes: 5068c7a883d1 ("crypto: pcrypt - Add pcrypt crypto parallelization wrapper")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Tested-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 33 insertions, 3 deletions

diff --git a/crypto/pcrypt.c b/crypto/pcrypt.c
index 81bbea7f2ba6..3e026e7a7e75 100644
--- a/crypto/pcrypt.c
+++ b/crypto/pcrypt.c
@@ -24,6 +24,8 @@ static struct kset           *pcrypt_kset;
 
 struct pcrypt_instance_ctx {
 	struct crypto_aead_spawn spawn;
+	struct padata_shell *psenc;
+	struct padata_shell *psdec;
 	atomic_t tfm_count;
 };
 
@@ -32,6 +34,12 @@ struct pcrypt_aead_ctx {
 	unsigned int cb_cpu;
 };
 
+static inline struct pcrypt_instance_ctx *pcrypt_tfm_ictx(
+	struct crypto_aead *tfm)
+{
+	return aead_instance_ctx(aead_alg_instance(tfm));
+}
+
 static int pcrypt_aead_setkey(struct crypto_aead *parent,
 			      const u8 *key, unsigned int keylen)
 {
@@ -90,6 +98,9 @@ static int pcrypt_aead_encrypt(struct aead_request *req)
 	struct crypto_aead *aead = crypto_aead_reqtfm(req);
 	struct pcrypt_aead_ctx *ctx = crypto_aead_ctx(aead);
 	u32 flags = aead_request_flags(req);
+	struct pcrypt_instance_ctx *ictx;
+
+	ictx = pcrypt_tfm_ictx(aead);
 
 	memset(padata, 0, sizeof(struct padata_priv));
 
@@ -103,7 +114,7 @@ static int pcrypt_aead_encrypt(struct aead_request *req)
 			       req->cryptlen, req->iv);
 	aead_request_set_ad(creq, req->assoclen);
 
-	err = padata_do_parallel(pencrypt, padata, &ctx->cb_cpu);
+	err = padata_do_parallel(ictx->psenc, padata, &ctx->cb_cpu);
 	if (!err)
 		return -EINPROGRESS;
 
@@ -132,6 +143,9 @@ static int pcrypt_aead_decrypt(struct aead_request *req)
 	struct crypto_aead *aead = crypto_aead_reqtfm(req);
 	struct pcrypt_aead_ctx *ctx = crypto_aead_ctx(aead);
 	u32 flags = aead_request_flags(req);
+	struct pcrypt_instance_ctx *ictx;
+
+	ictx = pcrypt_tfm_ictx(aead);
 
 	memset(padata, 0, sizeof(struct padata_priv));
 
@@ -145,7 +159,7 @@ static int pcrypt_aead_decrypt(struct aead_request *req)
 			       req->cryptlen, req->iv);
 	aead_request_set_ad(creq, req->assoclen);
 
-	err = padata_do_parallel(pdecrypt, padata, &ctx->cb_cpu);
+	err = padata_do_parallel(ictx->psdec, padata, &ctx->cb_cpu);
 	if (!err)
 		return -EINPROGRESS;
 
@@ -192,6 +206,8 @@ static void pcrypt_free(struct aead_instance *inst)
 	struct pcrypt_instance_ctx *ctx = aead_instance_ctx(inst);
 
 	crypto_drop_aead(&ctx->spawn);
+	padata_free_shell(ctx->psdec);
+	padata_free_shell(ctx->psenc);
 	kfree(inst);
 }
 
@@ -233,12 +249,22 @@ static int pcrypt_create_aead(struct crypto_template *tmpl, struct rtattr **tb,
 	if (!inst)
 		return -ENOMEM;
 
+	err = -ENOMEM;
+
 	ctx = aead_instance_ctx(inst);
+	ctx->psenc = padata_alloc_shell(pencrypt);
+	if (!ctx->psenc)
+		goto out_free_inst;
+
+	ctx->psdec = padata_alloc_shell(pdecrypt);
+	if (!ctx->psdec)
+		goto out_free_psenc;
+
 	crypto_set_aead_spawn(&ctx->spawn, aead_crypto_instance(inst));
 
 	err = crypto_grab_aead(&ctx->spawn, name, 0, 0);
 	if (err)
-		goto out_free_inst;
+		goto out_free_psdec;
 
 	alg = crypto_spawn_aead_alg(&ctx->spawn);
 	err = pcrypt_init_instance(aead_crypto_instance(inst), &alg->base);
@@ -271,6 +297,10 @@ out:
 
 out_drop_aead:
 	crypto_drop_aead(&ctx->spawn);
+out_free_psdec:
+	padata_free_shell(ctx->psdec);
+out_free_psenc:
+	padata_free_shell(ctx->psenc);
 out_free_inst:
 	kfree(inst);
 	goto out;