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net/tls: Remove VLA usage 

In the quest to remove VLAs from the kernel[1], this replaces the VLA
size with the only possible size used in the code, and adds a mechanism
to double-check future IV sizes.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Dave Watson <davejwatson@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Kees Cook 2018-04-10 17:52:34 -07:00 committed by David S. Miller
parent 08ea556e14
commit b16520f749
1 changed files with 9 additions and 1 deletions
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10
net/tls/tls_sw.c
View File

@ -41,6 +41,8 @@
#include <net/strparser.h>
#include <net/tls.h>
#define MAX_IV_SIZE TLS_CIPHER_AES_GCM_128_IV_SIZE
static int tls_do_decryption(struct sock *sk,
struct scatterlist *sgin,
struct scatterlist *sgout,
@ -673,7 +675,7 @@ static int decrypt_skb(struct sock *sk, struct sk_buff *skb,
{
struct tls_context *tls_ctx = tls_get_ctx(sk);
struct tls_sw_context *ctx = tls_sw_ctx(tls_ctx);
char iv[TLS_CIPHER_AES_GCM_128_SALT_SIZE + tls_ctx->rx.iv_size];
char iv[TLS_CIPHER_AES_GCM_128_SALT_SIZE + MAX_IV_SIZE];
struct scatterlist sgin_arr[MAX_SKB_FRAGS + 2];
struct scatterlist *sgin = &sgin_arr[0];
struct strp_msg *rxm = strp_msg(skb);
@ -1094,6 +1096,12 @@ int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx)
goto free_priv;
}
/* Sanity-check the IV size for stack allocations. */
if (iv_size > MAX_IV_SIZE) {
rc = -EINVAL;
goto free_priv;
}
cctx->prepend_size = TLS_HEADER_SIZE + nonce_size;
cctx->tag_size = tag_size;
cctx->overhead_size = cctx->prepend_size + cctx->tag_size;