Hi Herbert,
you see the reported problem by simply using
sa.salg_mask = 0xffffffff;
Note, I am not fully sure about whether CRYPTO_AF_ALG_ALLOWED_MASK and
CRYPTO_AF_ALG_ALLOWED_TYPE have the correct value. But I think that all
that user space should reach is potentially the ASYNC flag and the
cipher types flags.
---8<---
The user space interface allows specifying the type and the mask field
used to allocate the cipher. Only a subset of the type and mask is
considered relevant to be set by user space if needed at all.
This fixes a bug where user space is able to cause one cipher to be
registered multiple times potentially exhausting kernel memory.
Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Stephan Mueller <smueller@xxxxxxxxxx>
---
crypto/af_alg.c | 7 +++++++
crypto/algif_aead.c | 2 ++
crypto/algif_hash.c | 2 ++
crypto/algif_rng.c | 2 ++
crypto/algif_skcipher.c | 2 ++
include/crypto/if_alg.h | 1 +
include/linux/crypto.h | 3 +++
7 files changed, 19 insertions(+)
diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index 1e5353f62067..16cfbde64048 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -1172,6 +1172,13 @@ int af_alg_get_rsgl(struct sock *sk, struct msghdr *msg, int flags,
}
EXPORT_SYMBOL_GPL(af_alg_get_rsgl);
+void af_alg_restrict_type_mask(u32 *type, u32 *mask)
+{
+ *type &= CRYPTO_AF_ALG_ALLOWED_TYPE;
+ *mask &= CRYPTO_AF_ALG_ALLOWED_MASK;
+}
+EXPORT_SYMBOL_GPL(af_alg_restrict_type_mask);
+
static int __init af_alg_init(void)
{
int err = proto_register(&alg_proto, 0);
diff --git a/crypto/algif_aead.c b/crypto/algif_aead.c
index 9d73be28cf01..5d21db83bdfd 100644
--- a/crypto/algif_aead.c
+++ b/crypto/algif_aead.c
@@ -463,6 +463,8 @@ static void *aead_bind(const char *name, u32 type, u32 mask)
if (!tfm)
return ERR_PTR(-ENOMEM);
+ af_alg_restrict_type_mask(&type, &mask);
+
aead = crypto_alloc_aead(name, type, mask);
if (IS_ERR(aead)) {
kfree(tfm);
diff --git a/crypto/algif_hash.c b/crypto/algif_hash.c
index 76d2e716c792..f7660e80cd05 100644
--- a/crypto/algif_hash.c
+++ b/crypto/algif_hash.c
@@ -419,6 +419,8 @@ static void *hash_bind(const char *name, u32 type, u32 mask)
if (!tfm)
return ERR_PTR(-ENOMEM);
+ af_alg_restrict_type_mask(&type, &mask);
+
hash = crypto_alloc_ahash(name, type, mask);
if (IS_ERR(hash)) {
kfree(tfm);
diff --git a/crypto/algif_rng.c b/crypto/algif_rng.c
index 150c2b6480ed..33a7064996f2 100644
--- a/crypto/algif_rng.c
+++ b/crypto/algif_rng.c
@@ -116,6 +116,8 @@ static struct proto_ops algif_rng_ops = {
static void *rng_bind(const char *name, u32 type, u32 mask)
{
+ af_alg_restrict_type_mask(&type, &mask);
+
return crypto_alloc_rng(name, type, mask);
}
diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index 9954b078f0b9..0a4987aa9d5c 100644
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -314,6 +314,8 @@ static void *skcipher_bind(const char *name, u32 type, u32 mask)
if (!tfm)
return ERR_PTR(-ENOMEM);
+ af_alg_restrict_type_mask(&type, &mask);
+
skcipher = crypto_alloc_skcipher(name, type, mask);
if (IS_ERR(skcipher)) {
kfree(tfm);
diff --git a/include/crypto/if_alg.h b/include/crypto/if_alg.h
index 6abf0a3604dc..8ade69d46025 100644
--- a/include/crypto/if_alg.h
+++ b/include/crypto/if_alg.h
@@ -250,5 +250,6 @@ struct af_alg_async_req *af_alg_alloc_areq(struct sock *sk,
int af_alg_get_rsgl(struct sock *sk, struct msghdr *msg, int flags,
struct af_alg_async_req *areq, size_t maxsize,
size_t *outlen);
+void af_alg_restrict_type_mask(u32 *type, u32 *mask);
#endif /* _CRYPTO_IF_ALG_H */
diff --git a/include/linux/crypto.h b/include/linux/crypto.h
index 78508ca4b108..0d7694673fff 100644
--- a/include/linux/crypto.h
+++ b/include/linux/crypto.h
@@ -70,6 +70,9 @@
#define CRYPTO_ALG_DYING 0x00000040
#define CRYPTO_ALG_ASYNC 0x00000080
+#define CRYPTO_AF_ALG_ALLOWED_MASK 0x000000ff
+#define CRYPTO_AF_ALG_ALLOWED_TYPE 0x000000ff
+
/*
* Set this bit if and only if the algorithm requires another algorithm of
* the same type to handle corner cases.
--
2.14.3
