Revision 12d94a804946af291e24b80fc53ec86264765781 authored by Eric Dumazet on 15 August 2017, 11:09:51 UTC, committed by David S. Miller on 16 August 2017, 00:06:34 UTC
Based on a syzkaller report [1], I found that a per cpu allocation failure in snmp6_alloc_dev() would then lead to NULL dereference in ip6_route_dev_notify(). It seems this is a very old bug, thus no Fixes tag in this submission. Let's add in6_dev_put_clear() helper, as we will probably use it elsewhere (once available/present in net-next) [1] kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 1 PID: 17294 Comm: syz-executor6 Not tainted 4.13.0-rc2+ #10 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff88019f456680 task.stack: ffff8801c6e58000 RIP: 0010:__read_once_size include/linux/compiler.h:250 [inline] RIP: 0010:atomic_read arch/x86/include/asm/atomic.h:26 [inline] RIP: 0010:refcount_sub_and_test+0x7d/0x1b0 lib/refcount.c:178 RSP: 0018:ffff8801c6e5f1b0 EFLAGS: 00010202 RAX: 0000000000000037 RBX: dffffc0000000000 RCX: ffffc90005d25000 RDX: ffff8801c6e5f218 RSI: ffffffff82342bbf RDI: 0000000000000001 RBP: ffff8801c6e5f240 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff10038dcbe37 R13: 0000000000000006 R14: 0000000000000001 R15: 00000000000001b8 FS: 00007f21e0429700(0000) GS:ffff8801dc100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001ddbc22000 CR3: 00000001d632b000 CR4: 00000000001426e0 DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: refcount_dec_and_test+0x1a/0x20 lib/refcount.c:211 in6_dev_put include/net/addrconf.h:335 [inline] ip6_route_dev_notify+0x1c9/0x4a0 net/ipv6/route.c:3732 notifier_call_chain+0x136/0x2c0 kernel/notifier.c:93 __raw_notifier_call_chain kernel/notifier.c:394 [inline] raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401 call_netdevice_notifiers_info+0x51/0x90 net/core/dev.c:1678 call_netdevice_notifiers net/core/dev.c:1694 [inline] rollback_registered_many+0x91c/0xe80 net/core/dev.c:7107 rollback_registered+0x1be/0x3c0 net/core/dev.c:7149 register_netdevice+0xbcd/0xee0 net/core/dev.c:7587 register_netdev+0x1a/0x30 net/core/dev.c:7669 loopback_net_init+0x76/0x160 drivers/net/loopback.c:214 ops_init+0x10a/0x570 net/core/net_namespace.c:118 setup_net+0x313/0x710 net/core/net_namespace.c:294 copy_net_ns+0x27c/0x580 net/core/net_namespace.c:418 create_new_namespaces+0x425/0x880 kernel/nsproxy.c:107 unshare_nsproxy_namespaces+0xae/0x1e0 kernel/nsproxy.c:206 SYSC_unshare kernel/fork.c:2347 [inline] SyS_unshare+0x653/0xfa0 kernel/fork.c:2297 entry_SYSCALL_64_fastpath+0x1f/0xbe RIP: 0033:0x4512c9 RSP: 002b:00007f21e0428c08 EFLAGS: 00000216 ORIG_RAX: 0000000000000110 RAX: ffffffffffffffda RBX: 0000000000718150 RCX: 00000000004512c9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000062020200 RBP: 0000000000000086 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000216 R12: 00000000004b973d R13: 00000000ffffffff R14: 000000002001d000 R15: 00000000000002dd Code: 50 2b 34 82 c7 00 f1 f1 f1 f1 c7 40 04 04 f2 f2 f2 c7 40 08 f3 f3 f3 f3 e8 a1 43 39 ff 4c 89 f8 48 8b 95 70 ff ff ff 48 c1 e8 03 <0f> b6 0c 18 4c 89 f8 83 e0 07 83 c0 03 38 c8 7c 08 84 c9 0f 85 RIP: __read_once_size include/linux/compiler.h:250 [inline] RSP: ffff8801c6e5f1b0 RIP: atomic_read arch/x86/include/asm/atomic.h:26 [inline] RSP: ffff8801c6e5f1b0 RIP: refcount_sub_and_test+0x7d/0x1b0 lib/refcount.c:178 RSP: ffff8801c6e5f1b0 ---[ end trace e441d046c6410d31 ]--- Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent 0a6f041
esp6_offload.c
/*
* IPV6 GSO/GRO offload support
* Linux INET implementation
*
* Copyright (C) 2016 secunet Security Networks AG
* Author: Steffen Klassert <steffen.klassert@secunet.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* ESP GRO support
*/
#include <linux/skbuff.h>
#include <linux/init.h>
#include <net/protocol.h>
#include <crypto/aead.h>
#include <crypto/authenc.h>
#include <linux/err.h>
#include <linux/module.h>
#include <net/ip.h>
#include <net/xfrm.h>
#include <net/esp.h>
#include <linux/scatterlist.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <net/ip6_route.h>
#include <net/ipv6.h>
#include <linux/icmpv6.h>
static __u16 esp6_nexthdr_esp_offset(struct ipv6hdr *ipv6_hdr, int nhlen)
{
int off = sizeof(struct ipv6hdr);
struct ipv6_opt_hdr *exthdr;
if (likely(ipv6_hdr->nexthdr == NEXTHDR_ESP))
return offsetof(struct ipv6hdr, nexthdr);
while (off < nhlen) {
exthdr = (void *)ipv6_hdr + off;
if (exthdr->nexthdr == NEXTHDR_ESP)
return off;
off += ipv6_optlen(exthdr);
}
return 0;
}
static struct sk_buff **esp6_gro_receive(struct sk_buff **head,
struct sk_buff *skb)
{
int offset = skb_gro_offset(skb);
struct xfrm_offload *xo;
struct xfrm_state *x;
__be32 seq;
__be32 spi;
int nhoff;
int err;
skb_pull(skb, offset);
if ((err = xfrm_parse_spi(skb, IPPROTO_ESP, &spi, &seq)) != 0)
goto out;
xo = xfrm_offload(skb);
if (!xo || !(xo->flags & CRYPTO_DONE)) {
err = secpath_set(skb);
if (err)
goto out;
if (skb->sp->len == XFRM_MAX_DEPTH)
goto out;
x = xfrm_state_lookup(dev_net(skb->dev), skb->mark,
(xfrm_address_t *)&ipv6_hdr(skb)->daddr,
spi, IPPROTO_ESP, AF_INET6);
if (!x)
goto out;
skb->sp->xvec[skb->sp->len++] = x;
skb->sp->olen++;
xo = xfrm_offload(skb);
if (!xo) {
xfrm_state_put(x);
goto out;
}
}
xo->flags |= XFRM_GRO;
nhoff = esp6_nexthdr_esp_offset(ipv6_hdr(skb), offset);
if (!nhoff)
goto out;
IP6CB(skb)->nhoff = nhoff;
XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
XFRM_SPI_SKB_CB(skb)->family = AF_INET6;
XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
XFRM_SPI_SKB_CB(skb)->seq = seq;
/* We don't need to handle errors from xfrm_input, it does all
* the error handling and frees the resources on error. */
xfrm_input(skb, IPPROTO_ESP, spi, -2);
return ERR_PTR(-EINPROGRESS);
out:
skb_push(skb, offset);
NAPI_GRO_CB(skb)->same_flow = 0;
NAPI_GRO_CB(skb)->flush = 1;
return NULL;
}
static void esp6_gso_encap(struct xfrm_state *x, struct sk_buff *skb)
{
struct ip_esp_hdr *esph;
struct ipv6hdr *iph = ipv6_hdr(skb);
struct xfrm_offload *xo = xfrm_offload(skb);
int proto = iph->nexthdr;
skb_push(skb, -skb_network_offset(skb));
esph = ip_esp_hdr(skb);
*skb_mac_header(skb) = IPPROTO_ESP;
esph->spi = x->id.spi;
esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
xo->proto = proto;
}
static struct sk_buff *esp6_gso_segment(struct sk_buff *skb,
netdev_features_t features)
{
__u32 seq;
int err = 0;
struct sk_buff *skb2;
struct xfrm_state *x;
struct ip_esp_hdr *esph;
struct crypto_aead *aead;
struct sk_buff *segs = ERR_PTR(-EINVAL);
netdev_features_t esp_features = features;
struct xfrm_offload *xo = xfrm_offload(skb);
if (!xo)
goto out;
seq = xo->seq.low;
x = skb->sp->xvec[skb->sp->len - 1];
aead = x->data;
esph = ip_esp_hdr(skb);
if (esph->spi != x->id.spi)
goto out;
if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead)))
goto out;
__skb_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead));
skb->encap_hdr_csum = 1;
if (!(features & NETIF_F_HW_ESP))
esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
segs = x->outer_mode->gso_segment(x, skb, esp_features);
if (IS_ERR_OR_NULL(segs))
goto out;
__skb_pull(skb, skb->data - skb_mac_header(skb));
skb2 = segs;
do {
struct sk_buff *nskb = skb2->next;
xo = xfrm_offload(skb2);
xo->flags |= XFRM_GSO_SEGMENT;
xo->seq.low = seq;
xo->seq.hi = xfrm_replay_seqhi(x, seq);
if(!(features & NETIF_F_HW_ESP))
xo->flags |= CRYPTO_FALLBACK;
x->outer_mode->xmit(x, skb2);
err = x->type_offload->xmit(x, skb2, esp_features);
if (err) {
kfree_skb_list(segs);
return ERR_PTR(err);
}
if (!skb_is_gso(skb2))
seq++;
else
seq += skb_shinfo(skb2)->gso_segs;
skb_push(skb2, skb2->mac_len);
skb2 = nskb;
} while (skb2);
out:
return segs;
}
static int esp6_input_tail(struct xfrm_state *x, struct sk_buff *skb)
{
struct crypto_aead *aead = x->data;
if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead)))
return -EINVAL;
skb->ip_summed = CHECKSUM_NONE;
return esp6_input_done2(skb, 0);
}
static int esp6_xmit(struct xfrm_state *x, struct sk_buff *skb, netdev_features_t features)
{
int err;
int alen;
int blksize;
struct xfrm_offload *xo;
struct ip_esp_hdr *esph;
struct crypto_aead *aead;
struct esp_info esp;
bool hw_offload = true;
esp.inplace = true;
xo = xfrm_offload(skb);
if (!xo)
return -EINVAL;
if (!(features & NETIF_F_HW_ESP) || !x->xso.offload_handle ||
(x->xso.dev != skb->dev)) {
xo->flags |= CRYPTO_FALLBACK;
hw_offload = false;
}
esp.proto = xo->proto;
/* skb is pure payload to encrypt */
aead = x->data;
alen = crypto_aead_authsize(aead);
esp.tfclen = 0;
/* XXX: Add support for tfc padding here. */
blksize = ALIGN(crypto_aead_blocksize(aead), 4);
esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
esp.plen = esp.clen - skb->len - esp.tfclen;
esp.tailen = esp.tfclen + esp.plen + alen;
if (!hw_offload || (hw_offload && !skb_is_gso(skb))) {
esp.nfrags = esp6_output_head(x, skb, &esp);
if (esp.nfrags < 0)
return esp.nfrags;
}
esph = ip_esp_hdr(skb);
esph->spi = x->id.spi;
skb_push(skb, -skb_network_offset(skb));
if (xo->flags & XFRM_GSO_SEGMENT) {
esph->seq_no = htonl(xo->seq.low);
} else {
int len;
len = skb->len - sizeof(struct ipv6hdr);
if (len > IPV6_MAXPLEN)
len = 0;
ipv6_hdr(skb)->payload_len = htons(len);
}
if (hw_offload)
return 0;
esp.seqno = cpu_to_be64(xo->seq.low + ((u64)xo->seq.hi << 32));
err = esp6_output_tail(x, skb, &esp);
if (err < 0)
return err;
secpath_reset(skb);
return 0;
}
static const struct net_offload esp6_offload = {
.callbacks = {
.gro_receive = esp6_gro_receive,
.gso_segment = esp6_gso_segment,
},
};
static const struct xfrm_type_offload esp6_type_offload = {
.description = "ESP6 OFFLOAD",
.owner = THIS_MODULE,
.proto = IPPROTO_ESP,
.input_tail = esp6_input_tail,
.xmit = esp6_xmit,
.encap = esp6_gso_encap,
};
static int __init esp6_offload_init(void)
{
if (xfrm_register_type_offload(&esp6_type_offload, AF_INET6) < 0) {
pr_info("%s: can't add xfrm type offload\n", __func__);
return -EAGAIN;
}
return inet6_add_offload(&esp6_offload, IPPROTO_ESP);
}
static void __exit esp6_offload_exit(void)
{
if (xfrm_unregister_type_offload(&esp6_type_offload, AF_INET6) < 0)
pr_info("%s: can't remove xfrm type offload\n", __func__);
inet6_del_offload(&esp6_offload, IPPROTO_ESP);
}
module_init(esp6_offload_init);
module_exit(esp6_offload_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
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