From mboxrd@z Thu Jan 1 00:00:00 1970 From: Doron Roberts-Kedes Subject: [PATCH net-next,v3] net/tls: Calculate nsg for zerocopy path without skb_cow_data. Date: Mon, 6 Aug 2018 12:47:38 -0700 Message-ID: <20180806194738.981505-1-doronrk@fb.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Vakul Garg , Dave Watson , Boris Pismenny , Aviad Yehezkel , , Doron Roberts-Kedes To: "David S . Miller" Return-path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:57988 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727585AbeHFV6Z (ORCPT ); Mon, 6 Aug 2018 17:58:25 -0400 Received: from pps.filterd (m0089730.ppops.net [127.0.0.1]) by m0089730.ppops.net (8.16.0.22/8.16.0.22) with SMTP id w76JiQhE010412 for ; Mon, 6 Aug 2018 12:47:47 -0700 Received: from mail.thefacebook.com ([199.201.64.23]) by m0089730.ppops.net with ESMTP id 2kpuaxr9wa-6 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Mon, 06 Aug 2018 12:47:47 -0700 Sender: netdev-owner@vger.kernel.org List-ID: decrypt_skb fails if the number of sg elements required to map is greater than MAX_SKB_FRAGS. As noted by Vakul Garg, nsg must always be calculated, but skb_cow_data adds unnecessary memcpy's for the zerocopy case. The new function skb_nsg calculates the number of scatterlist elements required to map the skb without the extra overhead of skb_cow_data. This function mimics the structure of skb_to_sgvec. Fixes: c46234ebb4d1 ("tls: RX path for ktls") Signed-off-by: Doron Roberts-Kedes --- net/tls/tls_sw.c | 96 ++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 93 insertions(+), 3 deletions(-) diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c index ff3a6904a722..eb87f931a0d6 100644 --- a/net/tls/tls_sw.c +++ b/net/tls/tls_sw.c @@ -43,6 +43,80 @@ #define MAX_IV_SIZE TLS_CIPHER_AES_GCM_128_IV_SIZE +static int __skb_nsg(struct sk_buff *skb, int offset, int len, + unsigned int recursion_level) +{ + int start = skb_headlen(skb); + int i, copy = start - offset; + struct sk_buff *frag_iter; + int elt = 0; + + if (unlikely(recursion_level >= 24)) + return -EMSGSIZE; + + if (copy > 0) { + if (copy > len) + copy = len; + elt++; + len -= copy; + if (len == 0) + return elt; + offset += copy; + } + + for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { + int end; + + WARN_ON(start > offset + len); + + end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]); + copy = end - offset; + if (copy > 0) { + if (copy > len) + copy = len; + elt++; + len -= copy; + if (len == 0) + return elt; + offset += copy; + } + start = end; + } + + skb_walk_frags(skb, frag_iter) { + int end, ret; + + WARN_ON(start > offset + len); + + end = start + frag_iter->len; + copy = end - offset; + if (copy > 0) { + if (copy > len) + copy = len; + ret = __skb_nsg(frag_iter, offset - start, copy, + recursion_level + 1); + if (unlikely(ret < 0)) + return ret; + elt += ret; + len -= copy; + if (len == 0) + return elt; + offset += copy; + } + start = end; + } + BUG_ON(len); + return elt; +} + +/* Return the number of scatterlist elements required to completely map the + * skb, or -EMSGSIZE if the recursion depth is exceeded. + */ +static int skb_nsg(struct sk_buff *skb, int offset, int len) +{ + return __skb_nsg(skb, offset, len, 0); +} + static int tls_do_decryption(struct sock *sk, struct scatterlist *sgin, struct scatterlist *sgout, @@ -693,7 +767,7 @@ int decrypt_skb(struct sock *sk, struct sk_buff *skb, struct scatterlist sgin_arr[MAX_SKB_FRAGS + 2]; struct scatterlist *sgin = &sgin_arr[0]; struct strp_msg *rxm = strp_msg(skb); - int ret, nsg = ARRAY_SIZE(sgin_arr); + int ret, nsg; struct sk_buff *unused; ret = skb_copy_bits(skb, rxm->offset + TLS_HEADER_SIZE, @@ -704,11 +778,27 @@ int decrypt_skb(struct sock *sk, struct sk_buff *skb, memcpy(iv, tls_ctx->rx.iv, TLS_CIPHER_AES_GCM_128_SALT_SIZE); if (!sgout) { - nsg = skb_cow_data(skb, 0, &unused) + 1; + nsg = skb_cow_data(skb, 0, &unused); + } else { + nsg = skb_nsg(skb, + rxm->offset + tls_ctx->rx.prepend_size, + rxm->full_len - tls_ctx->rx.prepend_size); + if (nsg <= 0) + return nsg; + } + + // We need one extra for ctx->rx_aad_ciphertext + nsg++; + + if (nsg > ARRAY_SIZE(sgin_arr)) { sgin = kmalloc_array(nsg, sizeof(*sgin), sk->sk_allocation); - sgout = sgin; + if (!sgin) + return -ENOMEM; } + if (!sgout) + sgout = sgin; + sg_init_table(sgin, nsg); sg_set_buf(&sgin[0], ctx->rx_aad_ciphertext, TLS_AAD_SPACE_SIZE); -- 2.17.1