crypto: chacha20poly1305 - validate the digest size
If the rfc7539 template was instantiated with a hash algorithm with
digest size larger than 16 bytes (POLY1305_DIGEST_SIZE), then the digest
overran the 'tag' buffer in 'struct chachapoly_req_ctx', corrupting the
subsequent memory, including 'cryptlen'. This caused a crash during
crypto_skcipher_decrypt().
Fix it by, when instantiating the template, requiring that the
underlying hash algorithm has the digest size expected for Poly1305.
Reproducer:
#include <linux/if_alg.h>
#include <sys/socket.h>
#include <unistd.h>
int main()
{
int algfd, reqfd;
struct sockaddr_alg addr = {
.salg_type = "aead",
.salg_name = "rfc7539(chacha20,sha256)",
};
unsigned 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, sizeof(buf));
reqfd = accept(algfd, 0, 0);
write(reqfd, buf, 16);
read(reqfd, buf, 16);
}
Reported-by: syzbot <syzkaller@googlegroups.com>
Fixes: 71ebc4d1b2
("crypto: chacha20poly1305 - Add a ChaCha20-Poly1305 AEAD construction, RFC7539")
Cc: <stable@vger.kernel.org> # v4.2+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Родитель
d042566d8c
Коммит
e57121d08c
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@ -610,6 +610,11 @@ static int chachapoly_create(struct crypto_template *tmpl, struct rtattr **tb,
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algt->mask));
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if (IS_ERR(poly))
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return PTR_ERR(poly);
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poly_hash = __crypto_hash_alg_common(poly);
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err = -EINVAL;
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if (poly_hash->digestsize != POLY1305_DIGEST_SIZE)
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goto out_put_poly;
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err = -ENOMEM;
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inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
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@ -618,7 +623,6 @@ static int chachapoly_create(struct crypto_template *tmpl, struct rtattr **tb,
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ctx = aead_instance_ctx(inst);
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ctx->saltlen = CHACHAPOLY_IV_SIZE - ivsize;
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poly_hash = __crypto_hash_alg_common(poly);
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err = crypto_init_ahash_spawn(&ctx->poly, poly_hash,
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aead_crypto_instance(inst));
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if (err)
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