[PATCH] crypto: AF_ALG - limit mask and type
From: Stephan Müller <hidden>
Date: 2017-12-12 06:09:15
Also in:
lkml
Subsystem:
crypto api, the rest · Maintainers:
Herbert Xu, "David S. Miller", Linus Torvalds
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 <redacted> Cc: <redacted> Signed-off-by: Stephan Mueller <redacted> --- 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.
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2.14.3