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authorJakub Kicinski <jakub.kicinski@netronome.com>2019-05-09 16:14:07 -0700
committerDavid S. Miller <davem@davemloft.net>2019-05-09 16:37:39 -0700
commitb53f4976fb1f738573b5b76e21d3c2652fffb46b (patch)
tree7b72ad4d3694231a1a1cba89873957367474eb22 /net
parent88c80bee883e7687d2672f84fd6d0fa1cee3d348 (diff)
downloadlinux-b53f4976fb1f738573b5b76e21d3c2652fffb46b.tar.bz2
net/tls: handle errors from padding_length()
At the time padding_length() is called the record header is still part of the message. If malicious TLS 1.3 peer sends an all-zero record padding_length() will stop at the record header, and return full length of the data including the tail_size. Subsequent subtraction of prot->overhead_size from rxm->full_len will cause rxm->full_len to turn negative. skb accessors, however, will always catch resulting out-of-bounds operation, so in practice this fix comes down to returning the correct error code. It also fixes a set but not used warning. This code was added by commit 130b392c6cd6 ("net: tls: Add tls 1.3 support"). CC: Dave Watson <davejwatson@fb.com> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/tls/tls_sw.c30
1 files changed, 22 insertions, 8 deletions
diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index c02293fb10e6..d93f83f77864 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -119,23 +119,25 @@ static int skb_nsg(struct sk_buff *skb, int offset, int len)
}
static int padding_length(struct tls_sw_context_rx *ctx,
- struct tls_context *tls_ctx, struct sk_buff *skb)
+ struct tls_prot_info *prot, struct sk_buff *skb)
{
struct strp_msg *rxm = strp_msg(skb);
int sub = 0;
/* Determine zero-padding length */
- if (tls_ctx->prot_info.version == TLS_1_3_VERSION) {
+ if (prot->version == TLS_1_3_VERSION) {
char content_type = 0;
int err;
int back = 17;
while (content_type == 0) {
- if (back > rxm->full_len)
+ if (back > rxm->full_len - prot->prepend_size)
return -EBADMSG;
err = skb_copy_bits(skb,
rxm->offset + rxm->full_len - back,
&content_type, 1);
+ if (err)
+ return err;
if (content_type)
break;
sub++;
@@ -170,9 +172,17 @@ static void tls_decrypt_done(struct crypto_async_request *req, int err)
tls_err_abort(skb->sk, err);
} else {
struct strp_msg *rxm = strp_msg(skb);
- rxm->full_len -= padding_length(ctx, tls_ctx, skb);
- rxm->offset += prot->prepend_size;
- rxm->full_len -= prot->overhead_size;
+ int pad;
+
+ pad = padding_length(ctx, prot, skb);
+ if (pad < 0) {
+ ctx->async_wait.err = pad;
+ tls_err_abort(skb->sk, pad);
+ } else {
+ rxm->full_len -= pad;
+ rxm->offset += prot->prepend_size;
+ rxm->full_len -= prot->overhead_size;
+ }
}
/* After using skb->sk to propagate sk through crypto async callback
@@ -1478,7 +1488,7 @@ static int decrypt_skb_update(struct sock *sk, struct sk_buff *skb,
struct tls_prot_info *prot = &tls_ctx->prot_info;
int version = prot->version;
struct strp_msg *rxm = strp_msg(skb);
- int err = 0;
+ int pad, err = 0;
if (!ctx->decrypted) {
#ifdef CONFIG_TLS_DEVICE
@@ -1501,7 +1511,11 @@ static int decrypt_skb_update(struct sock *sk, struct sk_buff *skb,
*zc = false;
}
- rxm->full_len -= padding_length(ctx, tls_ctx, skb);
+ pad = padding_length(ctx, prot, skb);
+ if (pad < 0)
+ return pad;
+
+ rxm->full_len -= pad;
rxm->offset += prot->prepend_size;
rxm->full_len -= prot->overhead_size;
tls_advance_record_sn(sk, &tls_ctx->rx, version);