[PATCH 0/2] Netfilter fixes for net-next

Discussion:

Pablo Neira Ayuso

2014-10-09 18:27:39 UTC

Hi David,

This batch contains two fixes for what you have in your net-next,
they are:

1) Remove nf_send_reset6() from header file. This function now resides
in the nf_reject_ipv6 module. Reported by Eric Dumazet.

2) Fix wrong NFT_REJECT_ICMPX_MAX definition and adjust code to fix
errors reported by Dan Carpenter's static analysis tools.

You can pull these changes from:

git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next.git

Thanks!

----------------------------------------------------------------

The following changes since commit 4e62ccd901062c532673f4fda16c484de2c3c8fc:

Merge branch 'mlx4-next' (2014-10-06 01:04:21 -0400)

are available in the git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next.git master

for you to fetch changes up to f0d1f04f0a2f662b6b617e24d115fddcf6ef8723:

netfilter: fix wrong arithmetics regarding NFT_REJECT_ICMPX_MAX (2014-10-07 20:16:31 +0200)

----------------------------------------------------------------
Pablo Neira Ayuso (2):
netfilter: kill nf_send_reset6() from include/net/netfilter/ipv6/nf_reject.h
netfilter: fix wrong arithmetics regarding NFT_REJECT_ICMPX_MAX

include/net/netfilter/ipv6/nf_reject.h | 157 +-----------------------------
include/uapi/linux/netfilter/nf_tables.h | 2 +-
net/netfilter/nft_reject.c | 10 +-
3 files changed, 7 insertions(+), 162 deletions(-)
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Pablo Neira Ayuso

2014-10-09 18:27:41 UTC

Permalink

NFT_REJECT_ICMPX_MAX should be __NFT_REJECT_ICMPX_MAX - 1.

nft_reject_icmp_code() and nft_reject_icmpv6_code() are called from the
packet path, so BUG_ON in case we try to access an unknown abstracted
ICMP code. This should not happen since we already validate this from
nft_reject_{inet,bridge}_init().

Fixes: 51b0a5d ("netfilter: nft_reject: introduce icmp code abstraction for inet and bridge")
Reported-by: Dan Carpenter <***@oracle.com>
Signed-off-by: Pablo Neira Ayuso <***@netfilter.org>
---
include/uapi/linux/netfilter/nf_tables.h | 2 +-
net/netfilter/nft_reject.c | 10 ++++------
2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index c26df67..f31fe7b 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -774,7 +774,7 @@ enum nft_reject_inet_code {
NFT_REJECT_ICMPX_ADMIN_PROHIBITED,
__NFT_REJECT_ICMPX_MAX
};
-#define NFT_REJECT_ICMPX_MAX (__NFT_REJECT_ICMPX_MAX + 1)
+#define NFT_REJECT_ICMPX_MAX (__NFT_REJECT_ICMPX_MAX - 1)

/**
* enum nft_reject_attributes - nf_tables reject expression netlink attributes
diff --git a/net/netfilter/nft_reject.c b/net/netfilter/nft_reject.c
index ec8a456..57d3e1a 100644
--- a/net/netfilter/nft_reject.c
+++ b/net/netfilter/nft_reject.c
@@ -72,7 +72,7 @@ nla_put_failure:
}
EXPORT_SYMBOL_GPL(nft_reject_dump);

-static u8 icmp_code_v4[NFT_REJECT_ICMPX_MAX] = {
+static u8 icmp_code_v4[NFT_REJECT_ICMPX_MAX + 1] = {
[NFT_REJECT_ICMPX_NO_ROUTE] = ICMP_NET_UNREACH,
[NFT_REJECT_ICMPX_PORT_UNREACH] = ICMP_PORT_UNREACH,
[NFT_REJECT_ICMPX_HOST_UNREACH] = ICMP_HOST_UNREACH,
@@ -81,8 +81,7 @@ static u8 icmp_code_v4[NFT_REJECT_ICMPX_MAX] = {

int nft_reject_icmp_code(u8 code)
{
- if (code > NFT_REJECT_ICMPX_MAX)
- return -EINVAL;
+ BUG_ON(code > NFT_REJECT_ICMPX_MAX);

return icmp_code_v4[code];
}
@@ -90,7 +89,7 @@ int nft_reject_icmp_code(u8 code)
EXPORT_SYMBOL_GPL(nft_reject_icmp_code);

-static u8 icmp_code_v6[NFT_REJECT_ICMPX_MAX] = {
+static u8 icmp_code_v6[NFT_REJECT_ICMPX_MAX + 1] = {
[NFT_REJECT_ICMPX_NO_ROUTE] = ICMPV6_NOROUTE,
[NFT_REJECT_ICMPX_PORT_UNREACH] = ICMPV6_PORT_UNREACH,
[NFT_REJECT_ICMPX_HOST_UNREACH] = ICMPV6_ADDR_UNREACH,
@@ -99,8 +98,7 @@ static u8 icmp_code_v6[NFT_REJECT_ICMPX_MAX] = {

int nft_reject_icmpv6_code(u8 code)
{
- if (code > NFT_REJECT_ICMPX_MAX)
- return -EINVAL;
+ BUG_ON(code > NFT_REJECT_ICMPX_MAX);

return icmp_code_v6[code];
}

--
1.7.10.4

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Pablo Neira Ayuso

2014-10-09 18:27:40 UTC

Permalink

nf_send_reset6() now resides in net/ipv6/netfilter/nf_reject_ipv6.c

Fixes: c8d7b98 ("netfilter: move nf_send_resetX() code to nf_reject_ipvX modules")
Reported-by: Eric Dumazet <***@gmail.com>
Signed-off-by: Pablo Neira Ayuso <***@netfilter.org>
Acked-by: Eric Dumazet <***@google.com>
---
include/net/netfilter/ipv6/nf_reject.h | 157 +-------------------------------
1 file changed, 2 insertions(+), 155 deletions(-)

diff --git a/include/net/netfilter/ipv6/nf_reject.h b/include/net/netfilter/ipv6/nf_reject.h
index 7a10cfc..48e1881 100644
--- a/include/net/netfilter/ipv6/nf_reject.h
+++ b/include/net/netfilter/ipv6/nf_reject.h
@@ -1,11 +1,7 @@
#ifndef _IPV6_NF_REJECT_H
#define _IPV6_NF_REJECT_H

-#include <net/ipv6.h>
-#include <net/ip6_route.h>
-#include <net/ip6_fib.h>
-#include <net/ip6_checksum.h>
-#include <linux/netfilter_ipv6.h>
+#include <linux/icmpv6.h>

static inline void
nf_send_unreach6(struct net *net, struct sk_buff *skb_in, unsigned char code,
@@ -17,155 +13,6 @@ nf_send_unreach6(struct net *net, struct sk_buff *skb_in, unsigned char code,
icmpv6_send(skb_in, ICMPV6_DEST_UNREACH, code, 0);
}

-/* Send RST reply */
-static void nf_send_reset6(struct net *net, struct sk_buff *oldskb, int hook)
-{
- struct sk_buff *nskb;
- struct tcphdr otcph, *tcph;
- unsigned int otcplen, hh_len;
- int tcphoff, needs_ack;
- const struct ipv6hdr *oip6h = ipv6_hdr(oldskb);
- struct ipv6hdr *ip6h;
-#define DEFAULT_TOS_VALUE 0x0U
- const __u8 tclass = DEFAULT_TOS_VALUE;
- struct dst_entry *dst = NULL;
- u8 proto;
- __be16 frag_off;
- struct flowi6 fl6;
-
- if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) ||
- (!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) {
- pr_debug("addr is not unicast.\n");
- return;
- }
-
- proto = oip6h->nexthdr;
- tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data), &proto, &frag_off);
-
- if ((tcphoff < 0) || (tcphoff > oldskb->len)) {
- pr_debug("Cannot get TCP header.\n");
- return;
- }
-
- otcplen = oldskb->len - tcphoff;
-
- /* IP header checks: fragment, too short. */
- if (proto != IPPROTO_TCP || otcplen < sizeof(struct tcphdr)) {
- pr_debug("proto(%d) != IPPROTO_TCP, "
- "or too short. otcplen = %d\n",
- proto, otcplen);
- return;
- }
-
- if (skb_copy_bits(oldskb, tcphoff, &otcph, sizeof(struct tcphdr)))
- BUG();
-
- /* No RST for RST. */
- if (otcph.rst) {
- pr_debug("RST is set\n");
- return;
- }
-
- /* Check checksum. */
- if (nf_ip6_checksum(oldskb, hook, tcphoff, IPPROTO_TCP)) {
- pr_debug("TCP checksum is invalid\n");
- return;
- }
-
- memset(&fl6, 0, sizeof(fl6));
- fl6.flowi6_proto = IPPROTO_TCP;
- fl6.saddr = oip6h->daddr;
- fl6.daddr = oip6h->saddr;
- fl6.fl6_sport = otcph.dest;
- fl6.fl6_dport = otcph.source;
- security_skb_classify_flow(oldskb, flowi6_to_flowi(&fl6));
- dst = ip6_route_output(net, NULL, &fl6);
- if (dst == NULL || dst->error) {
- dst_release(dst);
- return;
- }
- dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0);
- if (IS_ERR(dst))
- return;
-
- hh_len = (dst->dev->hard_header_len + 15)&~15;
- nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr)
- + sizeof(struct tcphdr) + dst->trailer_len,
- GFP_ATOMIC);
-
- if (!nskb) {
- net_dbg_ratelimited("cannot alloc skb\n");
- dst_release(dst);
- return;
- }
-
- skb_dst_set(nskb, dst);
-
- skb_reserve(nskb, hh_len + dst->header_len);
-
- skb_put(nskb, sizeof(struct ipv6hdr));
- skb_reset_network_header(nskb);
- ip6h = ipv6_hdr(nskb);
- ip6_flow_hdr(ip6h, tclass, 0);
- ip6h->hop_limit = ip6_dst_hoplimit(dst);
- ip6h->nexthdr = IPPROTO_TCP;
- ip6h->saddr = oip6h->daddr;
- ip6h->daddr = oip6h->saddr;
-
- skb_reset_transport_header(nskb);
- tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr));
- /* Truncate to length (no data) */
- tcph->doff = sizeof(struct tcphdr)/4;
- tcph->source = otcph.dest;
- tcph->dest = otcph.source;
-
- if (otcph.ack) {
- needs_ack = 0;
- tcph->seq = otcph.ack_seq;
- tcph->ack_seq = 0;
- } else {
- needs_ack = 1;
- tcph->ack_seq = htonl(ntohl(otcph.seq) + otcph.syn + otcph.fin
- + otcplen - (otcph.doff<<2));
- tcph->seq = 0;
- }
-
- /* Reset flags */
- ((u_int8_t *)tcph)[13] = 0;
- tcph->rst = 1;
- tcph->ack = needs_ack;
- tcph->window = 0;
- tcph->urg_ptr = 0;
- tcph->check = 0;
-
- /* Adjust TCP checksum */
- tcph->check = csum_ipv6_magic(&ipv6_hdr(nskb)->saddr,
- &ipv6_hdr(nskb)->daddr,
- sizeof(struct tcphdr), IPPROTO_TCP,
- csum_partial(tcph,
- sizeof(struct tcphdr), 0));
-
- nf_ct_attach(nskb, oldskb);
-
-#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
- /* If we use ip6_local_out for bridged traffic, the MAC source on
- * the RST will be ours, instead of the destination's. This confuses
- * some routers/firewalls, and they drop the packet. So we need to
- * build the eth header using the original destination's MAC as the
- * source, and send the RST packet directly.
- */
- if (oldskb->nf_bridge) {
- struct ethhdr *oeth = eth_hdr(oldskb);
- nskb->dev = oldskb->nf_bridge->physindev;
- nskb->protocol = htons(ETH_P_IPV6);
- ip6h->payload_len = htons(sizeof(struct tcphdr));
- if (dev_hard_header(nskb, nskb->dev, ntohs(nskb->protocol),
- oeth->h_source, oeth->h_dest, nskb->len) < 0)
- return;
- dev_queue_xmit(nskb);
- } else
-#endif
- ip6_local_out(nskb);
-}
+void nf_send_reset6(struct net *net, struct sk_buff *oldskb, int hook);

#endif /* _IPV6_NF_REJECT_H */

Josh Boyer

2014-10-13 15:41:57 UTC

Permalink

Post by Pablo Neira Ayuso
nf_send_reset6() now resides in net/ipv6/netfilter/nf_reject_ipv6.c
Fixes: c8d7b98 ("netfilter: move nf_send_resetX() code to nf_reject_ipvX modules")
---
include/net/netfilter/ipv6/nf_reject.h | 157 +-------------------------------
1 file changed, 2 insertions(+), 155 deletions(-)

Hi All,

This morning I was testing a kernel build from Linus' tree as of Linux
v3.17-7639-g90eac7eee2f4. When I rebooted my test machines, I
couldn't ssh back into any of them. I poked around a bit and noticed
that it seems the iptables rules weren't getting loaded properly.
Traffic out worked fine, and I could ping the machine, but other
incoming traffic was blocked. Then I saw that the ip6t_REJECT and
ip6t_rpfilter modules were not being loaded on the bad kernel.
Looking in dmesg I see:

[ 14.619028] nf_reject_ipv6: module license 'unspecified' taints kernel.
[ 14.619125] nf_reject_ipv6: Unknown symbol ip6_local_out (err 0)

So I did a git bisect and it pointed to this patch:

[***@obiwan linux]$ git bisect bad
91c1a09b33c902e20e09d9742560cc238a714de5 is the first bad commit
commit 91c1a09b33c902e20e09d9742560cc238a714de5
Author: Pablo Neira Ayuso <***@netfilter.org>
Date: Tue Oct 7 18:48:12 2014 +0200

netfilter: kill nf_send_reset6() from include/net/netfilter/ipv6/nf_reject.h

nf_send_reset6() now resides in net/ipv6/netfilter/nf_reject_ipv6.c

Fixes: c8d7b98 ("netfilter: move nf_send_resetX() code to
nf_reject_ipvX modules")
Reported-by: Eric Dumazet <***@gmail.com>
Signed-off-by: Pablo Neira Ayuso <***@netfilter.org>
Acked-by: Eric Dumazet <***@google.com>

:040000 040000 ab5b61e7ba562e0b22d781a4322ed73c657878dc
71822a7e785c408dd55a6c4600144573de500512 M include
[***@obiwan linux]$

I've attached the bisect log.

Perhaps one too many header files were trimmed in this case?

josh

Florian Westphal

2014-10-13 15:55:10 UTC

Permalink

Post by Josh Boyer

Ouch. ip6_local_is EXPORT_SYMBOL_GPL.

http://patchwork.ozlabs.org/patch/398501/

should fix this.
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Josh Boyer

2014-10-13 16:01:37 UTC

Permalink

Post by Florian Westphal

Post by Josh Boyer

Ouch. ip6_local_is EXPORT_SYMBOL_GPL.
http://patchwork.ozlabs.org/patch/398501/
should fix this.

I believe you're correct. I dug in some more and I was just about to
send a similar patch. I'll add it on top of my builds and test it
out. Thanks for the pointer.

josh
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Josh Boyer

2014-10-13 17:18:06 UTC

Permalink

Post by Josh Boyer

Post by Florian Westphal

Post by Josh Boyer

Ouch. ip6_local_is EXPORT_SYMBOL_GPL.
http://patchwork.ozlabs.org/patch/398501/
should fix this.

I believe you're correct. I dug in some more and I was just about to
send a similar patch. I'll add it on top of my builds and test it
out. Thanks for the pointer.

The patch you pointed to does indeed fix the issues I was seeing.
Thank you very much for the fast response.

josh
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David Miller

2014-10-10 19:01:28 UTC

Permalink

From: Pablo Neira Ayuso <***@netfilter.org>
Date: Thu, 9 Oct 2014 20:27:39 +0200

Post by Pablo Neira Ayuso
This batch contains two fixes for what you have in your net-next,
1) Remove nf_send_reset6() from header file. This function now resides
in the nf_reject_ipv6 module. Reported by Eric Dumazet.
2) Fix wrong NFT_REJECT_ICMPX_MAX definition and adjust code to fix
errors reported by Dan Carpenter's static analysis tools.
git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next.git

Pulled, thanks Pablo.
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