kernel/linux.git/drivers/net/tun.c, branch v4.14.2

tun/tap: sanitize TUNSETSNDBUF input

2017-11-01T11:52:36+00:00

Syzkaller found several variants of the lockup below by setting negative values with the TUNSETSNDBUF ioctl. This patch adds a sanity check to both the tun and tap versions of this ioctl. watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [repro:2389] Modules linked in: irq event stamp: 329692056 hardirqs last enabled at (329692055): [] _raw_spin_unlock_irqrestore+0x31/0x75 hardirqs last disabled at (329692056): [] apic_timer_interrupt+0x98/0xb0 softirqs last enabled at (35659740): [] __do_softirq+0x328/0x48c softirqs last disabled at (35659731): [] irq_exit+0xbc/0xd0 CPU: 0 PID: 2389 Comm: repro Not tainted 4.14.0-rc7 #23 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 task: ffff880009452140 task.stack: ffff880006a20000 RIP: 0010:_raw_spin_lock_irqsave+0x11/0x80 RSP: 0018:ffff880006a27c50 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff10 RAX: ffff880009ac68d0 RBX: ffff880006a27ce0 RCX: 0000000000000000 RDX: 0000000000000001 RSI: ffff880006a27ce0 RDI: ffff880009ac6900 RBP: ffff880006a27c60 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: 000000000063ff00 R12: ffff880009ac6900 R13: ffff880006a27cf8 R14: 0000000000000001 R15: ffff880006a27cf8 FS: 00007f4be4838700(0000) GS:ffff88000cc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020101000 CR3: 0000000009616000 CR4: 00000000000006f0 Call Trace: prepare_to_wait+0x26/0xc0 sock_alloc_send_pskb+0x14e/0x270 ? remove_wait_queue+0x60/0x60 tun_get_user+0x2cc/0x19d0 ? __tun_get+0x60/0x1b0 tun_chr_write_iter+0x57/0x86 __vfs_write+0x156/0x1e0 vfs_write+0xf7/0x230 SyS_write+0x57/0xd0 entry_SYSCALL_64_fastpath+0x1f/0xbe RIP: 0033:0x7f4be4356df9 RSP: 002b:00007ffc18101c08 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f4be4356df9 RDX: 0000000000000046 RSI: 0000000020101000 RDI: 0000000000000005 RBP: 00007ffc18101c40 R08: 0000000000000001 R09: 0000000000000001 R10: 0000000000000001 R11: 0000000000000293 R12: 0000559c75f64780 R13: 00007ffc18101d30 R14: 0000000000000000 R15: 0000000000000000 Fixes: 33dccbb050bb ("tun: Limit amount of queued packets per device") Fixes: 20d29d7a916a ("net: macvtap driver") Signed-off-by: Craig Gallek Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller

tuntap: properly align skb->head before building skb

2017-10-28T10:05:28+00:00

An unaligned alloc_frag->offset caused by previous allocation will result an unaligned skb->head. This will lead unaligned skb_shared_info and then unaligned dataref which requires to be aligned for accessing on some architecture. Fix this by aligning alloc_frag->offset before the frag refilling. Fixes: 0bbd7dad34f8 ("tun: make tun_build_skb() thread safe") Cc: Eric Dumazet Cc: Willem de Bruijn Cc: Wei Wei Cc: Dmitry Vyukov Cc: Mark Rutland Reported-by: Wei Wei Signed-off-by: Jason Wang Signed-off-by: David S. Miller

tun: allow positive return values on dev_get_valid_name() call

2017-10-26T01:10:03+00:00

If the name argument of dev_get_valid_name() contains "%d", it will try to assign it a unit number in __dev__alloc_name() and return either the unit number (>= 0) or an error code (< 0). Considering positive values as error values prevent tun device creations relying this mechanism, therefor we should only consider negative values as errors here. Signed-off-by: Julien Gomes Acked-by: Cong Wang Signed-off-by: David S. Miller

tun: call dev_get_valid_name() before register_netdevice()

2017-10-16T20:02:54+00:00

register_netdevice() could fail early when we have an invalid dev name, in which case ->ndo_uninit() is not called. For tun device, this is a problem because a timer etc. are already initialized and it expects ->ndo_uninit() to clean them up. We could move these initializations into a ->ndo_init() so that register_netdevice() knows better, however this is still complicated due to the logic in tun_detach(). Therefore, I choose to just call dev_get_valid_name() before register_netdevice(), which is quicker and much easier to audit. And for this specific case, it is already enough. Fixes: 96442e42429e ("tuntap: choose the txq based on rxq") Reported-by: Dmitry Alexeev Cc: Jason Wang Cc: "Michael S. Tsirkin" Signed-off-by: Cong Wang Signed-off-by: David S. Miller

tun: bail out from tun_get_user() if the skb is empty

2017-09-28T15:37:28+00:00

KMSAN (https://github.com/google/kmsan) reported accessing uninitialized skb->data[0] in the case the skb is empty (i.e. skb->len is 0): ================================================ BUG: KMSAN: use of uninitialized memory in tun_get_user+0x19ba/0x3770 CPU: 0 PID: 3051 Comm: probe Not tainted 4.13.0+ #3140 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: ... __msan_warning_32+0x66/0xb0 mm/kmsan/kmsan_instr.c:477 tun_get_user+0x19ba/0x3770 drivers/net/tun.c:1301 tun_chr_write_iter+0x19f/0x300 drivers/net/tun.c:1365 call_write_iter ./include/linux/fs.h:1743 new_sync_write fs/read_write.c:457 __vfs_write+0x6c3/0x7f0 fs/read_write.c:470 vfs_write+0x3e4/0x770 fs/read_write.c:518 SYSC_write+0x12f/0x2b0 fs/read_write.c:565 SyS_write+0x55/0x80 fs/read_write.c:557 do_syscall_64+0x242/0x330 arch/x86/entry/common.c:284 entry_SYSCALL64_slow_path+0x25/0x25 arch/x86/entry/entry_64.S:245 ... origin: ... kmsan_poison_shadow+0x6e/0xc0 mm/kmsan/kmsan.c:211 slab_alloc_node mm/slub.c:2732 __kmalloc_node_track_caller+0x351/0x370 mm/slub.c:4351 __kmalloc_reserve net/core/skbuff.c:138 __alloc_skb+0x26a/0x810 net/core/skbuff.c:231 alloc_skb ./include/linux/skbuff.h:903 alloc_skb_with_frags+0x1d7/0xc80 net/core/skbuff.c:4756 sock_alloc_send_pskb+0xabf/0xfe0 net/core/sock.c:2037 tun_alloc_skb drivers/net/tun.c:1144 tun_get_user+0x9a8/0x3770 drivers/net/tun.c:1274 tun_chr_write_iter+0x19f/0x300 drivers/net/tun.c:1365 call_write_iter ./include/linux/fs.h:1743 new_sync_write fs/read_write.c:457 __vfs_write+0x6c3/0x7f0 fs/read_write.c:470 vfs_write+0x3e4/0x770 fs/read_write.c:518 SYSC_write+0x12f/0x2b0 fs/read_write.c:565 SyS_write+0x55/0x80 fs/read_write.c:557 do_syscall_64+0x242/0x330 arch/x86/entry/common.c:284 return_from_SYSCALL_64+0x0/0x6a arch/x86/entry/entry_64.S:245 ================================================ Make sure tun_get_user() doesn't touch skb->data[0] unless there is actual data. C reproducer below: ========================== // autogenerated by syzkaller (http://github.com/google/syzkaller) #define _GNU_SOURCE #include #include #include #include #include #include int main() { int sock = socket(PF_INET, SOCK_STREAM, IPPROTO_IP); int tun_fd = open("/dev/net/tun", O_RDWR); struct ifreq req; memset(&req, 0, sizeof(struct ifreq)); strcpy((char*)&req.ifr_name, "gre0"); req.ifr_flags = IFF_UP | IFF_MULTICAST; ioctl(tun_fd, TUNSETIFF, &req); ioctl(sock, SIOCSIFFLAGS, "gre0"); write(tun_fd, "hi", 0); return 0; } ========================== Signed-off-by: Alexander Potapenko Signed-off-by: David S. Miller

tun: rename generic_xdp to skb_xdp

2017-09-05T21:26:41+00:00

Rename "generic_xdp" to "skb_xdp" to avoid confusing it with the generic XDP which will be done at netif_receive_skb(). Cc: Daniel Borkmann Signed-off-by: Jason Wang Signed-off-by: David S. Miller

tun: reserve extra headroom only when XDP is set

2017-09-05T21:26:41+00:00

We reserve headroom unconditionally which could cause unnecessary stress on socket memory accounting because of increased trusesize. Fix this by only reserve extra headroom when XDP is set. Cc: Jakub Kicinski Signed-off-by: Jason Wang Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2017-08-22T00:06:42+00:00

tun: handle register_netdevice() failures properly

2017-08-18T22:55:35+00:00

syzkaller reported a double free [1], caused by the fact that tun driver was not updated properly when priv_destructor was added. When/if register_netdevice() fails, priv_destructor() must have been called already. [1] BUG: KASAN: double-free or invalid-free in selinux_tun_dev_free_security+0x15/0x20 security/selinux/hooks.c:5023 CPU: 0 PID: 2919 Comm: syzkaller227220 Not tainted 4.13.0-rc4+ #23 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:52 print_address_description+0x7f/0x260 mm/kasan/report.c:252 kasan_report_double_free+0x55/0x80 mm/kasan/report.c:333 kasan_slab_free+0xa0/0xc0 mm/kasan/kasan.c:514 __cache_free mm/slab.c:3503 [inline] kfree+0xd3/0x260 mm/slab.c:3820 selinux_tun_dev_free_security+0x15/0x20 security/selinux/hooks.c:5023 security_tun_dev_free_security+0x48/0x80 security/security.c:1512 tun_set_iff drivers/net/tun.c:1884 [inline] __tun_chr_ioctl+0x2ce6/0x3d50 drivers/net/tun.c:2064 tun_chr_ioctl+0x2a/0x40 drivers/net/tun.c:2309 vfs_ioctl fs/ioctl.c:45 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685 SYSC_ioctl fs/ioctl.c:700 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691 entry_SYSCALL_64_fastpath+0x1f/0xbe RIP: 0033:0x443ff9 RSP: 002b:00007ffc34271f68 EFLAGS: 00000217 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000443ff9 RDX: 0000000020533000 RSI: 00000000400454ca RDI: 0000000000000003 RBP: 0000000000000086 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000217 R12: 0000000000401ce0 R13: 0000000000401d70 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 2919: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc+0xaa/0xd0 mm/kasan/kasan.c:551 kmem_cache_alloc_trace+0x101/0x6f0 mm/slab.c:3627 kmalloc include/linux/slab.h:493 [inline] kzalloc include/linux/slab.h:666 [inline] selinux_tun_dev_alloc_security+0x49/0x170 security/selinux/hooks.c:5012 security_tun_dev_alloc_security+0x6d/0xa0 security/security.c:1506 tun_set_iff drivers/net/tun.c:1839 [inline] __tun_chr_ioctl+0x1730/0x3d50 drivers/net/tun.c:2064 tun_chr_ioctl+0x2a/0x40 drivers/net/tun.c:2309 vfs_ioctl fs/ioctl.c:45 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685 SYSC_ioctl fs/ioctl.c:700 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691 entry_SYSCALL_64_fastpath+0x1f/0xbe Freed by task 2919: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0x6e/0xc0 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3503 [inline] kfree+0xd3/0x260 mm/slab.c:3820 selinux_tun_dev_free_security+0x15/0x20 security/selinux/hooks.c:5023 security_tun_dev_free_security+0x48/0x80 security/security.c:1512 tun_free_netdev+0x13b/0x1b0 drivers/net/tun.c:1563 register_netdevice+0x8d0/0xee0 net/core/dev.c:7605 tun_set_iff drivers/net/tun.c:1859 [inline] __tun_chr_ioctl+0x1caf/0x3d50 drivers/net/tun.c:2064 tun_chr_ioctl+0x2a/0x40 drivers/net/tun.c:2309 vfs_ioctl fs/ioctl.c:45 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685 SYSC_ioctl fs/ioctl.c:700 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691 entry_SYSCALL_64_fastpath+0x1f/0xbe The buggy address belongs to the object at ffff8801d2843b40 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 0 bytes inside of 32-byte region [ffff8801d2843b40, ffff8801d2843b60) The buggy address belongs to the page: page:ffffea000660cea8 count:1 mapcount:0 mapping:ffff8801d2843000 index:0xffff8801d2843fc1 flags: 0x200000000000100(slab) raw: 0200000000000100 ffff8801d2843000 ffff8801d2843fc1 000000010000003f raw: ffffea0006626a40 ffffea00066141a0 ffff8801dbc00100 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801d2843a00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc ffff8801d2843a80: 00 00 00 fc fc fc fc fc fb fb fb fb fc fc fc fc >ffff8801d2843b00: 00 00 00 00 fc fc fc fc fb fb fb fb fc fc fc fc ^ ffff8801d2843b80: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc ffff8801d2843c00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc ================================================================== Fixes: cf124db566e6 ("net: Fix inconsistent teardown and release of private netdev state.") Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

tun: make tun_build_skb() thread safe

2017-08-16T21:27:35+00:00

tun_build_skb() is not thread safe since it uses per queue page frag, this will break things when multiple threads are sending through same queue. Switch to use per-thread generator (no lock involved). Fixes: 66ccbc9c87c2 ("tap: use build_skb() for small packet") Tested-by: Jason Wang Signed-off-by: Eric Dumazet Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin Signed-off-by: David S. Miller