kernel/linux.git/drivers/net/tun.c, branch v4.4.235

tun: fix use-after-free when register netdev failed

2019-09-21T05:12:41+00:00

[ Upstream commit 77f22f92dff8e7b45c7786a430626d38071d4670 ] I got a UAF repport in tun driver when doing fuzzy test: [ 466.269490] ================================================================== [ 466.271792] BUG: KASAN: use-after-free in tun_chr_read_iter+0x2ca/0x2d0 [ 466.271806] Read of size 8 at addr ffff888372139250 by task tun-test/2699 [ 466.271810] [ 466.271824] CPU: 1 PID: 2699 Comm: tun-test Not tainted 5.3.0-rc1-00001-g5a9433db2614-dirty #427 [ 466.271833] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014 [ 466.271838] Call Trace: [ 466.271858] dump_stack+0xca/0x13e [ 466.271871] ? tun_chr_read_iter+0x2ca/0x2d0 [ 466.271890] print_address_description+0x79/0x440 [ 466.271906] ? vprintk_func+0x5e/0xf0 [ 466.271920] ? tun_chr_read_iter+0x2ca/0x2d0 [ 466.271935] __kasan_report+0x15c/0x1df [ 466.271958] ? tun_chr_read_iter+0x2ca/0x2d0 [ 466.271976] kasan_report+0xe/0x20 [ 466.271987] tun_chr_read_iter+0x2ca/0x2d0 [ 466.272013] do_iter_readv_writev+0x4b7/0x740 [ 466.272032] ? default_llseek+0x2d0/0x2d0 [ 466.272072] do_iter_read+0x1c5/0x5e0 [ 466.272110] vfs_readv+0x108/0x180 [ 466.299007] ? compat_rw_copy_check_uvector+0x440/0x440 [ 466.299020] ? fsnotify+0x888/0xd50 [ 466.299040] ? __fsnotify_parent+0xd0/0x350 [ 466.299064] ? fsnotify_first_mark+0x1e0/0x1e0 [ 466.304548] ? vfs_write+0x264/0x510 [ 466.304569] ? ksys_write+0x101/0x210 [ 466.304591] ? do_preadv+0x116/0x1a0 [ 466.304609] do_preadv+0x116/0x1a0 [ 466.309829] do_syscall_64+0xc8/0x600 [ 466.309849] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 466.309861] RIP: 0033:0x4560f9 [ 466.309875] Code: 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 b8 ff ff ff f7 d8 64 89 01 48 [ 466.309889] RSP: 002b:00007ffffa5166e8 EFLAGS: 00000206 ORIG_RAX: 0000000000000127 [ 466.322992] RAX: ffffffffffffffda RBX: 0000000000400460 RCX: 00000000004560f9 [ 466.322999] RDX: 0000000000000003 RSI: 00000000200008c0 RDI: 0000000000000003 [ 466.323007] RBP: 00007ffffa516700 R08: 0000000000000004 R09: 0000000000000000 [ 466.323014] R10: 0000000000000000 R11: 0000000000000206 R12: 000000000040cb10 [ 466.323021] R13: 0000000000000000 R14: 00000000006d7018 R15: 0000000000000000 [ 466.323057] [ 466.323064] Allocated by task 2605: [ 466.335165] save_stack+0x19/0x80 [ 466.336240] __kasan_kmalloc.constprop.8+0xa0/0xd0 [ 466.337755] kmem_cache_alloc+0xe8/0x320 [ 466.339050] getname_flags+0xca/0x560 [ 466.340229] user_path_at_empty+0x2c/0x50 [ 466.341508] vfs_statx+0xe6/0x190 [ 466.342619] __do_sys_newstat+0x81/0x100 [ 466.343908] do_syscall_64+0xc8/0x600 [ 466.345303] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 466.347034] [ 466.347517] Freed by task 2605: [ 466.348471] save_stack+0x19/0x80 [ 466.349476] __kasan_slab_free+0x12e/0x180 [ 466.350726] kmem_cache_free+0xc8/0x430 [ 466.351874] putname+0xe2/0x120 [ 466.352921] filename_lookup+0x257/0x3e0 [ 466.354319] vfs_statx+0xe6/0x190 [ 466.355498] __do_sys_newstat+0x81/0x100 [ 466.356889] do_syscall_64+0xc8/0x600 [ 466.358037] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 466.359567] [ 466.360050] The buggy address belongs to the object at ffff888372139100 [ 466.360050] which belongs to the cache names_cache of size 4096 [ 466.363735] The buggy address is located 336 bytes inside of [ 466.363735] 4096-byte region [ffff888372139100, ffff88837213a100) [ 466.367179] The buggy address belongs to the page: [ 466.368604] page:ffffea000dc84e00 refcount:1 mapcount:0 mapping:ffff8883df1b4f00 index:0x0 compound_mapcount: 0 [ 466.371582] flags: 0x2fffff80010200(slab|head) [ 466.372910] raw: 002fffff80010200 dead000000000100 dead000000000122 ffff8883df1b4f00 [ 466.375209] raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000 [ 466.377778] page dumped because: kasan: bad access detected [ 466.379730] [ 466.380288] Memory state around the buggy address: [ 466.381844] ffff888372139100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 466.384009] ffff888372139180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 466.386131] >ffff888372139200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 466.388257] ^ [ 466.390234] ffff888372139280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 466.392512] ffff888372139300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 466.394667] ================================================================== tun_chr_read_iter() accessed the memory which freed by free_netdev() called by tun_set_iff(): CPUA CPUB tun_set_iff() alloc_netdev_mqs() tun_attach() tun_chr_read_iter() tun_get() tun_do_read() tun_ring_recv() register_netdevice() <-- inject error goto err_detach tun_detach_all() <-- set RCV_SHUTDOWN free_netdev() <-- called from err_free_dev path netdev_freemem() <-- free the memory without check refcount (In this path, the refcount cannot prevent freeing the memory of dev, and the memory will be used by dev_put() called by tun_chr_read_iter() on CPUB.) (Break from tun_ring_recv(), because RCV_SHUTDOWN is set) tun_put() dev_put() <-- use the memory freed by netdev_freemem() Put the publishing of tfile->tun after register_netdevice(), so tun_get() won't get the tun pointer that freed by err_detach path if register_netdevice() failed. Fixes: eb0fb363f920 ("tuntap: attach queue 0 before registering netdevice") Reported-by: Hulk Robot Suggested-by: Jason Wang Signed-off-by: Yang Yingliang Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

tun: forbid iface creation with rtnl ops

2018-12-17T20:55:09+00:00

[ Upstream commit 35b827b6d06199841a83839e8bb69c0cd13a28be ] It's not supported right now (the goal of the initial patch was to support 'ip link del' only). Before the patch: $ ip link add foo type tun [ 239.632660] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 [snip] [ 239.636410] RIP: 0010:register_netdevice+0x8e/0x3a0 This panic occurs because dev->netdev_ops is not set by tun_setup(). But to have something usable, it will require more than just setting netdev_ops. Fixes: f019a7a594d9 ("tun: Implement ip link del tunXXX") CC: Eric W. Biederman Signed-off-by: Nicolas Dichtel Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

tun: Consistently configure generic netdev params via rtnetlink

2018-11-21T08:27:31+00:00

[ Upstream commit df52eab23d703142c766ac00bdb8db19d71238d0 ] Configuring generic network device parameters on tun will fail in presence of IFLA_INFO_KIND attribute in IFLA_LINKINFO nested attribute since tun_validate() always return failure. This can be visualized with following ip-link(8) command sequences: # ip link set dev tun0 group 100 # ip link set dev tun0 group 100 type tun RTNETLINK answers: Invalid argument with contrast to dummy and veth drivers: # ip link set dev dummy0 group 100 # ip link set dev dummy0 type dummy # ip link set dev veth0 group 100 # ip link set dev veth0 group 100 type veth Fix by returning zero in tun_validate() when @data is NULL that is always in case since rtnl_link_ops->maxtype is zero in tun driver. Fixes: f019a7a594d9 ("tun: Implement ip link del tunXXX") Signed-off-by: Serhey Popovych Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

tun: allow positive return values on dev_get_valid_name() call

2017-11-18T10:11:06+00:00

[ Upstream commit 5c25f65fd1e42685f7ccd80e0621829c105785d9 ] 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 Signed-off-by: Greg Kroah-Hartman

tun: call dev_get_valid_name() before register_netdevice()

2017-11-18T10:11:05+00:00

[ Upstream commit 0ad646c81b2182f7fa67ec0c8c825e0ee165696d ] 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 Signed-off-by: Greg Kroah-Hartman

tun/tap: sanitize TUNSETSNDBUF input

2017-11-18T10:11:05+00:00

[ Upstream commit 93161922c658c714715686cd0cf69b090cb9bf1d ] 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 Signed-off-by: Greg Kroah-Hartman

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

2017-10-21T15:09:03+00:00

[ Upstream commit 2580c4c17aee3ad58e9751012bad278dd074ccae ] 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 Signed-off-by: Greg Kroah-Hartman

tun: read vnet_hdr_sz once

2017-02-18T15:39:27+00:00

[ Upstream commit e1edab87faf6ca30cd137e0795bc73aa9a9a22ec ] When IFF_VNET_HDR is enabled, a virtio_net header must precede data. Data length is verified to be greater than or equal to expected header length tun->vnet_hdr_sz before copying. Read this value once and cache locally, as it can be updated between the test and use (TOCTOU). Signed-off-by: Willem de Bruijn Reported-by: Dmitry Vyukov CC: Eric Dumazet Acked-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

tuntap: correctly wake up process during uninit

2016-06-24T17:18:16+00:00

[ Upstream commit addf8fc4acb1cf79492ac64966f07178793cb3d7 ] We used to check dev->reg_state against NETREG_REGISTERED after each time we are woke up. But after commit 9e641bdcfa4e ("net-tun: restructure tun_do_read for better sleep/wakeup efficiency"), it uses skb_recv_datagram() which does not check dev->reg_state. This will result if we delete a tun/tap device after a process is blocked in the reading. The device will wait for the reference count which was held by that process for ever. Fixes this by using RCV_SHUTDOWN which will be checked during sk_recv_datagram() before trying to wake up the process during uninit. Fixes: 9e641bdcfa4e ("net-tun: restructure tun_do_read for better sleep/wakeup efficiency") Cc: Eric Dumazet Cc: Xi Wang Cc: Michael S. Tsirkin Signed-off-by: Jason Wang Acked-by: Eric Dumazet Acked-by: Michael S. Tsirkin Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

tuntap: restore default qdisc

2016-04-20T06:42:06+00:00

[ Upstream commit 016adb7260f481168c03e09f785184d6d5278894 ] After commit f84bb1eac027 ("net: fix IFF_NO_QUEUE for drivers using alloc_netdev"), default qdisc was changed to noqueue because tuntap does not set tx_queue_len during .setup(). This patch restores default qdisc by setting tx_queue_len in tun_setup(). Fixes: f84bb1eac027 ("net: fix IFF_NO_QUEUE for drivers using alloc_netdev") Cc: Phil Sutter Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin Acked-by: Phil Sutter Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman