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| author | Jakub Kicinski <jakub.kicinski@netronome.com> | 2019-05-09 16:14:07 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-05-09 16:37:39 -0700 |
| commit | b53f4976fb1f738573b5b76e21d3c2652fffb46b (patch) | |
| tree | 7b72ad4d3694231a1a1cba89873957367474eb22 /net/tls/tls_sw.c | |
| parent | 88c80bee883e7687d2672f84fd6d0fa1cee3d348 (diff) | |
| download | lwn-b53f4976fb1f738573b5b76e21d3c2652fffb46b.tar.gz lwn-b53f4976fb1f738573b5b76e21d3c2652fffb46b.zip | |
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/tls/tls_sw.c')
| -rw-r--r-- | net/tls/tls_sw.c | 30 |
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); |