linux.git/net/ipv6, branch v6.9-rc4

netfilter: complete validation of user input

2024-04-11T02:42:56+00:00

In my recent commit, I missed that do_replace() handlers
use copy_from_sockptr() (which I fixed), followed
by unsafe copy_from_sockptr_offset() calls.

In all functions, we can perform the @optlen validation
before even calling xt_alloc_table_info() with the following
check:

if ((u64)optlen < (u64)tmp.size + sizeof(tmp))
        return -EINVAL;

Fixes: 0c83842df40f ("netfilter: validate user input for expected length")
Reported-by: syzbot 
Signed-off-by: Eric Dumazet 
Reviewed-by: Pablo Neira Ayuso 
Link: https://lore.kernel.org/r/20240409120741.3538135-1-edumazet@google.com
Signed-off-by: Jakub Kicinski

ipv6: fix race condition between ipv6_get_ifaddr and ipv6_del_addr

2024-04-10T00:09:05+00:00

Although ipv6_get_ifaddr walks inet6_addr_lst under the RCU lock, it
still means hlist_for_each_entry_rcu can return an item that got removed
from the list. The memory itself of such item is not freed thanks to RCU
but nothing guarantees the actual content of the memory is sane.

In particular, the reference count can be zero. This can happen if
ipv6_del_addr is called in parallel. ipv6_del_addr removes the entry
from inet6_addr_lst (hlist_del_init_rcu(&ifp->addr_lst)) and drops all
references (__in6_ifa_put(ifp) + in6_ifa_put(ifp)). With bad enough
timing, this can happen:

1. In ipv6_get_ifaddr, hlist_for_each_entry_rcu returns an entry.

2. Then, the whole ipv6_del_addr is executed for the given entry. The
   reference count drops to zero and kfree_rcu is scheduled.

3. ipv6_get_ifaddr continues and tries to increments the reference count
   (in6_ifa_hold).

4. The rcu is unlocked and the entry is freed.

5. The freed entry is returned.

Prevent increasing of the reference count in such case. The name
in6_ifa_hold_safe is chosen to mimic the existing fib6_info_hold_safe.

[   41.506330] refcount_t: addition on 0; use-after-free.
[   41.506760] WARNING: CPU: 0 PID: 595 at lib/refcount.c:25 refcount_warn_saturate+0xa5/0x130
[   41.507413] Modules linked in: veth bridge stp llc
[   41.507821] CPU: 0 PID: 595 Comm: python3 Not tainted 6.9.0-rc2.main-00208-g49563be82afa #14
[   41.508479] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
[   41.509163] RIP: 0010:refcount_warn_saturate+0xa5/0x130
[   41.509586] Code: ad ff 90 0f 0b 90 90 c3 cc cc cc cc 80 3d c0 30 ad 01 00 75 a0 c6 05 b7 30 ad 01 01 90 48 c7 c7 38 cc 7a 8c e8 cc 18 ad ff 90 <0f> 0b 90 90 c3 cc cc cc cc 80 3d 98 30 ad 01 00 0f 85 75 ff ff ff
[   41.510956] RSP: 0018:ffffbda3c026baf0 EFLAGS: 00010282
[   41.511368] RAX: 0000000000000000 RBX: ffff9e9c46914800 RCX: 0000000000000000
[   41.511910] RDX: ffff9e9c7ec29c00 RSI: ffff9e9c7ec1c900 RDI: ffff9e9c7ec1c900
[   41.512445] RBP: ffff9e9c43660c9c R08: 0000000000009ffb R09: 00000000ffffdfff
[   41.512998] R10: 00000000ffffdfff R11: ffffffff8ca58a40 R12: ffff9e9c4339a000
[   41.513534] R13: 0000000000000001 R14: ffff9e9c438a0000 R15: ffffbda3c026bb48
[   41.514086] FS:  00007fbc4cda1740(0000) GS:ffff9e9c7ec00000(0000) knlGS:0000000000000000
[   41.514726] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   41.515176] CR2: 000056233b337d88 CR3: 000000000376e006 CR4: 0000000000370ef0
[   41.515713] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   41.516252] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   41.516799] Call Trace:
[   41.517037]  
[   41.517249]  ? __warn+0x7b/0x120
[   41.517535]  ? refcount_warn_saturate+0xa5/0x130
[   41.517923]  ? report_bug+0x164/0x190
[   41.518240]  ? handle_bug+0x3d/0x70
[   41.518541]  ? exc_invalid_op+0x17/0x70
[   41.520972]  ? asm_exc_invalid_op+0x1a/0x20
[   41.521325]  ? refcount_warn_saturate+0xa5/0x130
[   41.521708]  ipv6_get_ifaddr+0xda/0xe0
[   41.522035]  inet6_rtm_getaddr+0x342/0x3f0
[   41.522376]  ? __pfx_inet6_rtm_getaddr+0x10/0x10
[   41.522758]  rtnetlink_rcv_msg+0x334/0x3d0
[   41.523102]  ? netlink_unicast+0x30f/0x390
[   41.523445]  ? __pfx_rtnetlink_rcv_msg+0x10/0x10
[   41.523832]  netlink_rcv_skb+0x53/0x100
[   41.524157]  netlink_unicast+0x23b/0x390
[   41.524484]  netlink_sendmsg+0x1f2/0x440
[   41.524826]  __sys_sendto+0x1d8/0x1f0
[   41.525145]  __x64_sys_sendto+0x1f/0x30
[   41.525467]  do_syscall_64+0xa5/0x1b0
[   41.525794]  entry_SYSCALL_64_after_hwframe+0x72/0x7a
[   41.526213] RIP: 0033:0x7fbc4cfcea9a
[   41.526528] Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb b8 0f 1f 00 f3 0f 1e fa 41 89 ca 64 8b 04 25 18 00 00 00 85 c0 75 15 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 7e c3 0f 1f 44 00 00 41 54 48 83 ec 30 44 89
[   41.527942] RSP: 002b:00007ffcf54012a8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
[   41.528593] RAX: ffffffffffffffda RBX: 00007ffcf5401368 RCX: 00007fbc4cfcea9a
[   41.529173] RDX: 000000000000002c RSI: 00007fbc4b9d9bd0 RDI: 0000000000000005
[   41.529786] RBP: 00007fbc4bafb040 R08: 00007ffcf54013e0 R09: 000000000000000c
[   41.530375] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
[   41.530977] R13: ffffffffc4653600 R14: 0000000000000001 R15: 00007fbc4ca85d1b
[   41.531573]  

Fixes: 5c578aedcb21d ("IPv6: convert addrconf hash list to RCU")
Reviewed-by: Eric Dumazet 
Reviewed-by: David Ahern 
Signed-off-by: Jiri Benc 
Link: https://lore.kernel.org/r/8ab821e36073a4a406c50ec83c9e8dc586c539e4.1712585809.git.jbenc@redhat.com
Signed-off-by: Jakub Kicinski

ipv6: fib: hide unused 'pn' variable

2024-04-09T13:49:19+00:00

When CONFIG_IPV6_SUBTREES is disabled, the only user is hidden, causing
a 'make W=1' warning:

net/ipv6/ip6_fib.c: In function 'fib6_add':
net/ipv6/ip6_fib.c:1388:32: error: variable 'pn' set but not used [-Werror=unused-but-set-variable]

Add another #ifdef around the variable declaration, matching the other
uses in this file.

Fixes: 66729e18df08 ("[IPV6] ROUTE: Make sure we have fn->leaf when adding a node on subtree.")
Link: https://lore.kernel.org/netdev/20240322131746.904943-1-arnd@kernel.org/
Reviewed-by: David Ahern 
Signed-off-by: Arnd Bergmann 
Reviewed-by: Eric Dumazet 
Link: https://lore.kernel.org/r/20240408074219.3030256-1-arnd@kernel.org
Signed-off-by: Paolo Abeni

netfilter: validate user input for expected length

2024-04-04T16:39:52+00:00

I got multiple syzbot reports showing old bugs exposed
by BPF after commit 20f2505fb436 ("bpf: Try to avoid kzalloc
in cgroup/{s,g}etsockopt")

setsockopt() @optlen argument should be taken into account
before copying data.

 BUG: KASAN: slab-out-of-bounds in copy_from_sockptr_offset include/linux/sockptr.h:49 [inline]
 BUG: KASAN: slab-out-of-bounds in copy_from_sockptr include/linux/sockptr.h:55 [inline]
 BUG: KASAN: slab-out-of-bounds in do_replace net/ipv4/netfilter/ip_tables.c:1111 [inline]
 BUG: KASAN: slab-out-of-bounds in do_ipt_set_ctl+0x902/0x3dd0 net/ipv4/netfilter/ip_tables.c:1627
Read of size 96 at addr ffff88802cd73da0 by task syz-executor.4/7238

CPU: 1 PID: 7238 Comm: syz-executor.4 Not tainted 6.9.0-rc2-next-20240403-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 
  __dump_stack lib/dump_stack.c:88 [inline]
  dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
  print_address_description mm/kasan/report.c:377 [inline]
  print_report+0x169/0x550 mm/kasan/report.c:488
  kasan_report+0x143/0x180 mm/kasan/report.c:601
  kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
  __asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105
  copy_from_sockptr_offset include/linux/sockptr.h:49 [inline]
  copy_from_sockptr include/linux/sockptr.h:55 [inline]
  do_replace net/ipv4/netfilter/ip_tables.c:1111 [inline]
  do_ipt_set_ctl+0x902/0x3dd0 net/ipv4/netfilter/ip_tables.c:1627
  nf_setsockopt+0x295/0x2c0 net/netfilter/nf_sockopt.c:101
  do_sock_setsockopt+0x3af/0x720 net/socket.c:2311
  __sys_setsockopt+0x1ae/0x250 net/socket.c:2334
  __do_sys_setsockopt net/socket.c:2343 [inline]
  __se_sys_setsockopt net/socket.c:2340 [inline]
  __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2340
 do_syscall_64+0xfb/0x240
 entry_SYSCALL_64_after_hwframe+0x72/0x7a
RIP: 0033:0x7fd22067dde9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fd21f9ff0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007fd2207abf80 RCX: 00007fd22067dde9
RDX: 0000000000000040 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007fd2206ca47a R08: 0000000000000001 R09: 0000000000000000
R10: 0000000020000880 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007fd2207abf80 R15: 00007ffd2d0170d8
 

Allocated by task 7238:
  kasan_save_stack mm/kasan/common.c:47 [inline]
  kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
  poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
  __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387
  kasan_kmalloc include/linux/kasan.h:211 [inline]
  __do_kmalloc_node mm/slub.c:4069 [inline]
  __kmalloc_noprof+0x200/0x410 mm/slub.c:4082
  kmalloc_noprof include/linux/slab.h:664 [inline]
  __cgroup_bpf_run_filter_setsockopt+0xd47/0x1050 kernel/bpf/cgroup.c:1869
  do_sock_setsockopt+0x6b4/0x720 net/socket.c:2293
  __sys_setsockopt+0x1ae/0x250 net/socket.c:2334
  __do_sys_setsockopt net/socket.c:2343 [inline]
  __se_sys_setsockopt net/socket.c:2340 [inline]
  __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2340
 do_syscall_64+0xfb/0x240
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

The buggy address belongs to the object at ffff88802cd73da0
 which belongs to the cache kmalloc-8 of size 8
The buggy address is located 0 bytes inside of
 allocated 1-byte region [ffff88802cd73da0, ffff88802cd73da1)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88802cd73020 pfn:0x2cd73
flags: 0xfff80000000000(node=0|zone=1|lastcpupid=0xfff)
page_type: 0xffffefff(slab)
raw: 00fff80000000000 ffff888015041280 dead000000000100 dead000000000122
raw: ffff88802cd73020 000000008080007f 00000001ffffefff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 5103, tgid 2119833701 (syz-executor.4), ts 5103, free_ts 70804600828
  set_page_owner include/linux/page_owner.h:32 [inline]
  post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1490
  prep_new_page mm/page_alloc.c:1498 [inline]
  get_page_from_freelist+0x2e7e/0x2f40 mm/page_alloc.c:3454
  __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4712
  __alloc_pages_node_noprof include/linux/gfp.h:244 [inline]
  alloc_pages_node_noprof include/linux/gfp.h:271 [inline]
  alloc_slab_page+0x5f/0x120 mm/slub.c:2249
  allocate_slab+0x5a/0x2e0 mm/slub.c:2412
  new_slab mm/slub.c:2465 [inline]
  ___slab_alloc+0xcd1/0x14b0 mm/slub.c:3615
  __slab_alloc+0x58/0xa0 mm/slub.c:3705
  __slab_alloc_node mm/slub.c:3758 [inline]
  slab_alloc_node mm/slub.c:3936 [inline]
  __do_kmalloc_node mm/slub.c:4068 [inline]
  kmalloc_node_track_caller_noprof+0x286/0x450 mm/slub.c:4089
  kstrdup+0x3a/0x80 mm/util.c:62
  device_rename+0xb5/0x1b0 drivers/base/core.c:4558
  dev_change_name+0x275/0x860 net/core/dev.c:1232
  do_setlink+0xa4b/0x41f0 net/core/rtnetlink.c:2864
  __rtnl_newlink net/core/rtnetlink.c:3680 [inline]
  rtnl_newlink+0x180b/0x20a0 net/core/rtnetlink.c:3727
  rtnetlink_rcv_msg+0x89b/0x10d0 net/core/rtnetlink.c:6594
  netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2559
  netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline]
  netlink_unicast+0x7ea/0x980 net/netlink/af_netlink.c:1361
page last free pid 5146 tgid 5146 stack trace:
  reset_page_owner include/linux/page_owner.h:25 [inline]
  free_pages_prepare mm/page_alloc.c:1110 [inline]
  free_unref_page+0xd3c/0xec0 mm/page_alloc.c:2617
  discard_slab mm/slub.c:2511 [inline]
  __put_partials+0xeb/0x130 mm/slub.c:2980
  put_cpu_partial+0x17c/0x250 mm/slub.c:3055
  __slab_free+0x2ea/0x3d0 mm/slub.c:4254
  qlink_free mm/kasan/quarantine.c:163 [inline]
  qlist_free_all+0x9e/0x140 mm/kasan/quarantine.c:179
  kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286
  __kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:322
  kasan_slab_alloc include/linux/kasan.h:201 [inline]
  slab_post_alloc_hook mm/slub.c:3888 [inline]
  slab_alloc_node mm/slub.c:3948 [inline]
  __do_kmalloc_node mm/slub.c:4068 [inline]
  __kmalloc_node_noprof+0x1d7/0x450 mm/slub.c:4076
  kmalloc_node_noprof include/linux/slab.h:681 [inline]
  kvmalloc_node_noprof+0x72/0x190 mm/util.c:634
  bucket_table_alloc lib/rhashtable.c:186 [inline]
  rhashtable_rehash_alloc+0x9e/0x290 lib/rhashtable.c:367
  rht_deferred_worker+0x4e1/0x2440 lib/rhashtable.c:427
  process_one_work kernel/workqueue.c:3218 [inline]
  process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3299
  worker_thread+0x86d/0xd70 kernel/workqueue.c:3380
  kthread+0x2f0/0x390 kernel/kthread.c:388
  ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243

Memory state around the buggy address:
 ffff88802cd73c80: 07 fc fc fc 05 fc fc fc 05 fc fc fc fa fc fc fc
 ffff88802cd73d00: fa fc fc fc fa fc fc fc fa fc fc fc fa fc fc fc
>ffff88802cd73d80: fa fc fc fc 01 fc fc fc fa fc fc fc fa fc fc fc
                               ^
 ffff88802cd73e00: fa fc fc fc fa fc fc fc 05 fc fc fc 07 fc fc fc
 ffff88802cd73e80: 07 fc fc fc 07 fc fc fc 07 fc fc fc 07 fc fc fc

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: syzbot 
Signed-off-by: Eric Dumazet 
Reviewed-by: Pablo Neira Ayuso 
Link: https://lore.kernel.org/r/20240404122051.2303764-1-edumazet@google.com
Signed-off-by: Jakub Kicinski

ipv6: Fix infinite recursion in fib6_dump_done().

2024-04-03T02:10:57+00:00

syzkaller reported infinite recursive calls of fib6_dump_done() during
netlink socket destruction.  [1]

From the log, syzkaller sent an AF_UNSPEC RTM_GETROUTE message, and then
the response was generated.  The following recvmmsg() resumed the dump
for IPv6, but the first call of inet6_dump_fib() failed at kzalloc() due
to the fault injection.  [0]

  12:01:34 executing program 3:
  r0 = socket$nl_route(0x10, 0x3, 0x0)
  sendmsg$nl_route(r0, ... snip ...)
  recvmmsg(r0, ... snip ...) (fail_nth: 8)

Here, fib6_dump_done() was set to nlk_sk(sk)->cb.done, and the next call
of inet6_dump_fib() set it to nlk_sk(sk)->cb.args[3].  syzkaller stopped
receiving the response halfway through, and finally netlink_sock_destruct()
called nlk_sk(sk)->cb.done().

fib6_dump_done() calls fib6_dump_end() and nlk_sk(sk)->cb.done() if it
is still not NULL.  fib6_dump_end() rewrites nlk_sk(sk)->cb.done() by
nlk_sk(sk)->cb.args[3], but it has the same function, not NULL, calling
itself recursively and hitting the stack guard page.

To avoid the issue, let's set the destructor after kzalloc().

[0]:
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
CPU: 1 PID: 432110 Comm: syz-executor.3 Not tainted 6.8.0-12821-g537c2e91d354-dirty #11
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
Call Trace:
 
 dump_stack_lvl (lib/dump_stack.c:117)
 should_fail_ex (lib/fault-inject.c:52 lib/fault-inject.c:153)
 should_failslab (mm/slub.c:3733)
 kmalloc_trace (mm/slub.c:3748 mm/slub.c:3827 mm/slub.c:3992)
 inet6_dump_fib (./include/linux/slab.h:628 ./include/linux/slab.h:749 net/ipv6/ip6_fib.c:662)
 rtnl_dump_all (net/core/rtnetlink.c:4029)
 netlink_dump (net/netlink/af_netlink.c:2269)
 netlink_recvmsg (net/netlink/af_netlink.c:1988)
 ____sys_recvmsg (net/socket.c:1046 net/socket.c:2801)
 ___sys_recvmsg (net/socket.c:2846)
 do_recvmmsg (net/socket.c:2943)
 __x64_sys_recvmmsg (net/socket.c:3041 net/socket.c:3034 net/socket.c:3034)

[1]:
BUG: TASK stack guard page was hit at 00000000f2fa9af1 (stack is 00000000b7912430..000000009a436beb)
stack guard page: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 223719 Comm: kworker/1:3 Not tainted 6.8.0-12821-g537c2e91d354-dirty #11
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
Workqueue: events netlink_sock_destruct_work
RIP: 0010:fib6_dump_done (net/ipv6/ip6_fib.c:570)
Code: 3c 24 e8 f3 e9 51 fd e9 28 fd ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 f3 0f 1e fa 41 57 41 56 41 55 41 54 55 48 89 fd <53> 48 8d 5d 60 e8 b6 4d 07 fd 48 89 da 48 b8 00 00 00 00 00 fc ff
RSP: 0018:ffffc9000d980000 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffffff84405990 RCX: ffffffff844059d3
RDX: ffff8881028e0000 RSI: ffffffff84405ac2 RDI: ffff88810c02f358
RBP: ffff88810c02f358 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000224 R12: 0000000000000000
R13: ffff888007c82c78 R14: ffff888007c82c68 R15: ffff888007c82c68
FS:  0000000000000000(0000) GS:ffff88811b100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffc9000d97fff8 CR3: 0000000102309002 CR4: 0000000000770ef0
PKRU: 55555554
Call Trace:
 <#DF>
 
 
 fib6_dump_done (net/ipv6/ip6_fib.c:572 (discriminator 1))
 fib6_dump_done (net/ipv6/ip6_fib.c:572 (discriminator 1))
 ...
 fib6_dump_done (net/ipv6/ip6_fib.c:572 (discriminator 1))
 fib6_dump_done (net/ipv6/ip6_fib.c:572 (discriminator 1))
 netlink_sock_destruct (net/netlink/af_netlink.c:401)
 __sk_destruct (net/core/sock.c:2177 (discriminator 2))
 sk_destruct (net/core/sock.c:2224)
 __sk_free (net/core/sock.c:2235)
 sk_free (net/core/sock.c:2246)
 process_one_work (kernel/workqueue.c:3259)
 worker_thread (kernel/workqueue.c:3329 kernel/workqueue.c:3416)
 kthread (kernel/kthread.c:388)
 ret_from_fork (arch/x86/kernel/process.c:153)
 ret_from_fork_asm (arch/x86/entry/entry_64.S:256)
Modules linked in:

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: syzkaller 
Signed-off-by: Kuniyuki Iwashima 
Reviewed-by: Eric Dumazet 
Reviewed-by: David Ahern 
Link: https://lore.kernel.org/r/20240401211003.25274-1-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski

erspan: make sure erspan_base_hdr is present in skb->head

2024-03-29T19:42:55+00:00

syzbot reported a problem in ip6erspan_rcv() [1]

Issue is that ip6erspan_rcv() (and erspan_rcv()) no longer make
sure erspan_base_hdr is present in skb linear part (skb->head)
before getting @ver field from it.

Add the missing pskb_may_pull() calls.

v2: Reload iph pointer in erspan_rcv() after pskb_may_pull()
    because skb->head might have changed.

[1]

 BUG: KMSAN: uninit-value in pskb_may_pull_reason include/linux/skbuff.h:2742 [inline]
 BUG: KMSAN: uninit-value in pskb_may_pull include/linux/skbuff.h:2756 [inline]
 BUG: KMSAN: uninit-value in ip6erspan_rcv net/ipv6/ip6_gre.c:541 [inline]
 BUG: KMSAN: uninit-value in gre_rcv+0x11f8/0x1930 net/ipv6/ip6_gre.c:610
  pskb_may_pull_reason include/linux/skbuff.h:2742 [inline]
  pskb_may_pull include/linux/skbuff.h:2756 [inline]
  ip6erspan_rcv net/ipv6/ip6_gre.c:541 [inline]
  gre_rcv+0x11f8/0x1930 net/ipv6/ip6_gre.c:610
  ip6_protocol_deliver_rcu+0x1d4c/0x2ca0 net/ipv6/ip6_input.c:438
  ip6_input_finish net/ipv6/ip6_input.c:483 [inline]
  NF_HOOK include/linux/netfilter.h:314 [inline]
  ip6_input+0x15d/0x430 net/ipv6/ip6_input.c:492
  ip6_mc_input+0xa7e/0xc80 net/ipv6/ip6_input.c:586
  dst_input include/net/dst.h:460 [inline]
  ip6_rcv_finish+0x955/0x970 net/ipv6/ip6_input.c:79
  NF_HOOK include/linux/netfilter.h:314 [inline]
  ipv6_rcv+0xde/0x390 net/ipv6/ip6_input.c:310
  __netif_receive_skb_one_core net/core/dev.c:5538 [inline]
  __netif_receive_skb+0x1da/0xa00 net/core/dev.c:5652
  netif_receive_skb_internal net/core/dev.c:5738 [inline]
  netif_receive_skb+0x58/0x660 net/core/dev.c:5798
  tun_rx_batched+0x3ee/0x980 drivers/net/tun.c:1549
  tun_get_user+0x5566/0x69e0 drivers/net/tun.c:2002
  tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048
  call_write_iter include/linux/fs.h:2108 [inline]
  new_sync_write fs/read_write.c:497 [inline]
  vfs_write+0xb63/0x1520 fs/read_write.c:590
  ksys_write+0x20f/0x4c0 fs/read_write.c:643
  __do_sys_write fs/read_write.c:655 [inline]
  __se_sys_write fs/read_write.c:652 [inline]
  __x64_sys_write+0x93/0xe0 fs/read_write.c:652
 do_syscall_64+0xd5/0x1f0
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

Uninit was created at:
  slab_post_alloc_hook mm/slub.c:3804 [inline]
  slab_alloc_node mm/slub.c:3845 [inline]
  kmem_cache_alloc_node+0x613/0xc50 mm/slub.c:3888
  kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:577
  __alloc_skb+0x35b/0x7a0 net/core/skbuff.c:668
  alloc_skb include/linux/skbuff.h:1318 [inline]
  alloc_skb_with_frags+0xc8/0xbf0 net/core/skbuff.c:6504
  sock_alloc_send_pskb+0xa81/0xbf0 net/core/sock.c:2795
  tun_alloc_skb drivers/net/tun.c:1525 [inline]
  tun_get_user+0x209a/0x69e0 drivers/net/tun.c:1846
  tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048
  call_write_iter include/linux/fs.h:2108 [inline]
  new_sync_write fs/read_write.c:497 [inline]
  vfs_write+0xb63/0x1520 fs/read_write.c:590
  ksys_write+0x20f/0x4c0 fs/read_write.c:643
  __do_sys_write fs/read_write.c:655 [inline]
  __se_sys_write fs/read_write.c:652 [inline]
  __x64_sys_write+0x93/0xe0 fs/read_write.c:652
 do_syscall_64+0xd5/0x1f0
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

CPU: 1 PID: 5045 Comm: syz-executor114 Not tainted 6.9.0-rc1-syzkaller-00021-g962490525cff #0

Fixes: cb73ee40b1b3 ("net: ip_gre: use erspan key field for tunnel lookup")
Reported-by: syzbot+1c1cf138518bf0c53d68@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/000000000000772f2c0614b66ef7@google.com/
Signed-off-by: Eric Dumazet 
Cc: Lorenzo Bianconi 
Link: https://lore.kernel.org/r/20240328112248.1101491-1-edumazet@google.com
Signed-off-by: Jakub Kicinski

udp: do not transition UDP GRO fraglist partial checksums to unnecessary

2024-03-29T11:30:44+00:00

UDP GRO validates checksums and in udp4/6_gro_complete fraglist packets
are converted to CHECKSUM_UNNECESSARY to avoid later checks. However
this is an issue for CHECKSUM_PARTIAL packets as they can be looped in
an egress path and then their partial checksums are not fixed.

Different issues can be observed, from invalid checksum on packets to
traces like:

  gen01: hw csum failure
  skb len=3008 headroom=160 headlen=1376 tailroom=0
  mac=(106,14) net=(120,40) trans=160
  shinfo(txflags=0 nr_frags=0 gso(size=0 type=0 segs=0))
  csum(0xffff232e ip_summed=2 complete_sw=0 valid=0 level=0)
  hash(0x77e3d716 sw=1 l4=1) proto=0x86dd pkttype=0 iif=12
  ...

Fix this by only converting CHECKSUM_NONE packets to
CHECKSUM_UNNECESSARY by reusing __skb_incr_checksum_unnecessary. All
other checksum types are kept as-is, including CHECKSUM_COMPLETE as
fraglist packets being segmented back would have their skb->csum valid.

Fixes: 9fd1ff5d2ac7 ("udp: Support UDP fraglist GRO/GSO.")
Signed-off-by: Antoine Tenart 
Reviewed-by: Willem de Bruijn 
Signed-off-by: David S. Miller

udp: do not accept non-tunnel GSO skbs landing in a tunnel

2024-03-29T11:30:43+00:00

When rx-udp-gro-forwarding is enabled UDP packets might be GROed when
being forwarded. If such packets might land in a tunnel this can cause
various issues and udp_gro_receive makes sure this isn't the case by
looking for a matching socket. This is performed in
udp4/6_gro_lookup_skb but only in the current netns. This is an issue
with tunneled packets when the endpoint is in another netns. In such
cases the packets will be GROed at the UDP level, which leads to various
issues later on. The same thing can happen with rx-gro-list.

We saw this with geneve packets being GROed at the UDP level. In such
case gso_size is set; later the packet goes through the geneve rx path,
the geneve header is pulled, the offset are adjusted and frag_list skbs
are not adjusted with regard to geneve. When those skbs hit
skb_fragment, it will misbehave. Different outcomes are possible
depending on what the GROed skbs look like; from corrupted packets to
kernel crashes.

One example is a BUG_ON[1] triggered in skb_segment while processing the
frag_list. Because gso_size is wrong (geneve header was pulled)
skb_segment thinks there is "geneve header size" of data in frag_list,
although it's in fact the next packet. The BUG_ON itself has nothing to
do with the issue. This is only one of the potential issues.

Looking up for a matching socket in udp_gro_receive is fragile: the
lookup could be extended to all netns (not speaking about performances)
but nothing prevents those packets from being modified in between and we
could still not find a matching socket. It's OK to keep the current
logic there as it should cover most cases but we also need to make sure
we handle tunnel packets being GROed too early.

This is done by extending the checks in udp_unexpected_gso: GSO packets
lacking the SKB_GSO_UDP_TUNNEL/_CSUM bits and landing in a tunnel must
be segmented.

[1] kernel BUG at net/core/skbuff.c:4408!
    RIP: 0010:skb_segment+0xd2a/0xf70
    __udp_gso_segment+0xaa/0x560

Fixes: 9fd1ff5d2ac7 ("udp: Support UDP fraglist GRO/GSO.")
Fixes: 36707061d6ba ("udp: allow forwarding of plain (non-fraglisted) UDP GRO packets")
Signed-off-by: Antoine Tenart 
Reviewed-by: Willem de Bruijn 
Signed-off-by: David S. Miller

inet: inet_defrag: prevent sk release while still in use

2024-03-28T11:06:22+00:00

ip_local_out() and other functions can pass skb->sk as function argument.

If the skb is a fragment and reassembly happens before such function call
returns, the sk must not be released.

This affects skb fragments reassembled via netfilter or similar
modules, e.g. openvswitch or ct_act.c, when run as part of tx pipeline.

Eric Dumazet made an initial analysis of this bug.  Quoting Eric:
  Calling ip_defrag() in output path is also implying skb_orphan(),
  which is buggy because output path relies on sk not disappearing.

  A relevant old patch about the issue was :
  8282f27449bf ("inet: frag: Always orphan skbs inside ip_defrag()")

  [..]

  net/ipv4/ip_output.c depends on skb->sk being set, and probably to an
  inet socket, not an arbitrary one.

  If we orphan the packet in ipvlan, then downstream things like FQ
  packet scheduler will not work properly.

  We need to change ip_defrag() to only use skb_orphan() when really
  needed, ie whenever frag_list is going to be used.

Eric suggested to stash sk in fragment queue and made an initial patch.
However there is a problem with this:

If skb is refragmented again right after, ip_do_fragment() will copy
head->sk to the new fragments, and sets up destructor to sock_wfree.
IOW, we have no choice but to fix up sk_wmem accouting to reflect the
fully reassembled skb, else wmem will underflow.

This change moves the orphan down into the core, to last possible moment.
As ip_defrag_offset is aliased with sk_buff->sk member, we must move the
offset into the FRAG_CB, else skb->sk gets clobbered.

This allows to delay the orphaning long enough to learn if the skb has
to be queued or if the skb is completing the reasm queue.

In the former case, things work as before, skb is orphaned.  This is
safe because skb gets queued/stolen and won't continue past reasm engine.

In the latter case, we will steal the skb->sk reference, reattach it to
the head skb, and fix up wmem accouting when inet_frag inflates truesize.

Fixes: 7026b1ddb6b8 ("netfilter: Pass socket pointer down through okfn().")
Diagnosed-by: Eric Dumazet 
Reported-by: xingwei lee 
Reported-by: yue sun 
Reported-by: syzbot+e5167d7144a62715044c@syzkaller.appspotmail.com
Signed-off-by: Florian Westphal 
Reviewed-by: Eric Dumazet 
Link: https://lore.kernel.org/r/20240326101845.30836-1-fw@strlen.de
Signed-off-by: Paolo Abeni

ipv6: Fix address dump when IPv6 is disabled on an interface

2024-03-23T01:03:40+00:00

Cited commit started returning an error when user space requests to dump
the interface's IPv6 addresses and IPv6 is disabled on the interface.
Restore the previous behavior and do not return an error.

Before cited commit:

 # ip address show dev dummy1
 2: dummy1:  mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
     link/ether 1a:52:02:5a:c2:6e brd ff:ff:ff:ff:ff:ff
     inet6 fe80::1852:2ff:fe5a:c26e/64 scope link proto kernel_ll
        valid_lft forever preferred_lft forever
 # ip link set dev dummy1 mtu 1000
 # ip address show dev dummy1
 2: dummy1:  mtu 1000 qdisc noqueue state UNKNOWN group default qlen 1000
     link/ether 1a:52:02:5a:c2:6e brd ff:ff:ff:ff:ff:ff

After cited commit:

 # ip address show dev dummy1
 2: dummy1:  mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
     link/ether 1e:9b:94:00:ac:e8 brd ff:ff:ff:ff:ff:ff
     inet6 fe80::1c9b:94ff:fe00:ace8/64 scope link proto kernel_ll
        valid_lft forever preferred_lft forever
 # ip link set dev dummy1 mtu 1000
 # ip address show dev dummy1
 RTNETLINK answers: No such device
 Dump terminated

With this patch:

 # ip address show dev dummy1
 2: dummy1:  mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
     link/ether 42:35:fc:53:66:cf brd ff:ff:ff:ff:ff:ff
     inet6 fe80::4035:fcff:fe53:66cf/64 scope link proto kernel_ll
        valid_lft forever preferred_lft forever
 # ip link set dev dummy1 mtu 1000
 # ip address show dev dummy1
 2: dummy1:  mtu 1000 qdisc noqueue state UNKNOWN group default qlen 1000
     link/ether 42:35:fc:53:66:cf brd ff:ff:ff:ff:ff:ff

Fixes: 9cc4cc329d30 ("ipv6: use xa_array iterator to implement inet6_dump_addr()")
Reported-by: Gal Pressman 
Closes: https://lore.kernel.org/netdev/7e261328-42eb-411d-b1b4-ad884eeaae4d@linux.dev/
Tested-by: Gal Pressman 
Signed-off-by: Ido Schimmel 
Reviewed-by: Eric Dumazet 
Link: https://lore.kernel.org/r/20240321173042.2151756-1-idosch@nvidia.com
Signed-off-by: Jakub Kicinski