mirror of
https://github.com/Divested-Mobile/DivestOS-Build.git
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95 lines
2.9 KiB
Diff
95 lines
2.9 KiB
Diff
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From 197c949e7798fbf28cfadc69d9ca0c2abbf93191 Mon Sep 17 00:00:00 2001
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From: Eric Dumazet <edumazet@google.com>
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Date: Wed, 30 Dec 2015 08:51:12 -0500
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Subject: udp: properly support MSG_PEEK with truncated buffers
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Backport of this upstream commit into stable kernels :
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89c22d8c3b27 ("net: Fix skb csum races when peeking")
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exposed a bug in udp stack vs MSG_PEEK support, when user provides
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a buffer smaller than skb payload.
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In this case,
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skb_copy_and_csum_datagram_iovec(skb, sizeof(struct udphdr),
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msg->msg_iov);
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returns -EFAULT.
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This bug does not happen in upstream kernels since Al Viro did a great
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job to replace this into :
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skb_copy_and_csum_datagram_msg(skb, sizeof(struct udphdr), msg);
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This variant is safe vs short buffers.
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For the time being, instead reverting Herbert Xu patch and add back
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skb->ip_summed invalid changes, simply store the result of
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udp_lib_checksum_complete() so that we avoid computing the checksum a
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second time, and avoid the problematic
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skb_copy_and_csum_datagram_iovec() call.
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This patch can be applied on recent kernels as it avoids a double
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checksumming, then backported to stable kernels as a bug fix.
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Signed-off-by: Eric Dumazet <edumazet@google.com>
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Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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net/ipv4/udp.c | 6 ++++--
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net/ipv6/udp.c | 6 ++++--
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2 files changed, 8 insertions(+), 4 deletions(-)
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diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
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index 8841e98..ac14ae4 100644
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--- a/net/ipv4/udp.c
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+++ b/net/ipv4/udp.c
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@@ -1271,6 +1271,7 @@ int udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
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int peeked, off = 0;
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int err;
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int is_udplite = IS_UDPLITE(sk);
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+ bool checksum_valid = false;
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bool slow;
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if (flags & MSG_ERRQUEUE)
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@@ -1296,11 +1297,12 @@ try_again:
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*/
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if (copied < ulen || UDP_SKB_CB(skb)->partial_cov) {
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- if (udp_lib_checksum_complete(skb))
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+ checksum_valid = !udp_lib_checksum_complete(skb);
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+ if (!checksum_valid)
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goto csum_copy_err;
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}
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- if (skb_csum_unnecessary(skb))
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+ if (checksum_valid || skb_csum_unnecessary(skb))
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err = skb_copy_datagram_msg(skb, sizeof(struct udphdr),
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msg, copied);
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else {
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diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
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index 9da3287..00775ee 100644
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--- a/net/ipv6/udp.c
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+++ b/net/ipv6/udp.c
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@@ -402,6 +402,7 @@ int udpv6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
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int peeked, off = 0;
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int err;
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int is_udplite = IS_UDPLITE(sk);
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+ bool checksum_valid = false;
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int is_udp4;
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bool slow;
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@@ -433,11 +434,12 @@ try_again:
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*/
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if (copied < ulen || UDP_SKB_CB(skb)->partial_cov) {
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- if (udp_lib_checksum_complete(skb))
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+ checksum_valid = !udp_lib_checksum_complete(skb);
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+ if (!checksum_valid)
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goto csum_copy_err;
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}
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- if (skb_csum_unnecessary(skb))
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+ if (checksum_valid || skb_csum_unnecessary(skb))
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err = skb_copy_datagram_msg(skb, sizeof(struct udphdr),
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msg, copied);
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else {
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--
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cgit v1.1
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