110 lines
3.8 KiB
Diff
110 lines
3.8 KiB
Diff
From: Jan Niehusmann <jan@gondor.com>
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Date: Fri, 14 Apr 2017 21:26:27 +0200
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Subject: udp: properly support MSG_PEEK with truncated buffers
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Add upstream patch to fix CVE-2016-10229
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diff --git a/target/linux/generic/patches-3.18/001-udp-properly-support-MSG_PEEK-with-truncated-buffers.patch b/target/linux/generic/patches-3.18/001-udp-properly-support-MSG_PEEK-with-truncated-buffers.patch
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new file mode 100644
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index 0000000000000000000000000000000000000000..16edc8c8da4ce8edf3ce1b5c2a56d543f9658897
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--- /dev/null
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+++ b/target/linux/generic/patches-3.18/001-udp-properly-support-MSG_PEEK-with-truncated-buffers.patch
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@@ -0,0 +1,97 @@
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+From 69335972b1c1c9bd7597fc6080b6eb1bd3fbf774 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: [PATCH] udp: properly support MSG_PEEK with truncated buffers
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+
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+[ Upstream commit 197c949e7798fbf28cfadc69d9ca0c2abbf93191 ]
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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
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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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+
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+diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
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+index 2a5d388..ee26711 100644
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+--- a/net/ipv4/udp.c
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++++ b/net/ipv4/udp.c
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+@@ -1252,6 +1252,7 @@ int udp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
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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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+
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+ if (flags & MSG_ERRQUEUE)
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+@@ -1277,11 +1278,12 @@ try_again:
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+ */
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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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+
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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_iovec(skb, sizeof(struct udphdr),
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+ msg->msg_iov, 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 7d01116..143e6c7 100644
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+--- a/net/ipv6/udp.c
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++++ b/net/ipv6/udp.c
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+@@ -388,6 +388,7 @@ int udpv6_recvmsg(struct kiocb *iocb, struct sock *sk,
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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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+
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+@@ -419,11 +420,12 @@ try_again:
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+ */
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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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+
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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_iovec(skb, sizeof(struct udphdr),
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+ msg->msg_iov, copied);
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+ else {
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+--
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+2.1.4
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+
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