kernel/linux.git/drivers/net/ppp, branch v4.17.1

ppp: remove the PPPIOCDETACH ioctl

2018-05-25T02:55:07+00:00

The PPPIOCDETACH ioctl effectively tries to "close" the given ppp file before f_count has reached 0, which is fundamentally a bad idea. It does check 'f_count < 2', which excludes concurrent operations on the file since they would only be possible with a shared fd table, in which case each fdget() would take a file reference. However, it fails to account for the fact that even with 'f_count == 1' the file can still be linked into epoll instances. As reported by syzbot, this can trivially be used to cause a use-after-free. Yet, the only known user of PPPIOCDETACH is pppd versions older than ppp-2.4.2, which was released almost 15 years ago (November 2003). Also, PPPIOCDETACH apparently stopped working reliably at around the same time, when the f_count check was added to the kernel, e.g. see https://lkml.org/lkml/2002/12/31/83. Also, the current 'f_count < 2' check makes PPPIOCDETACH only work in single-threaded applications; it always fails if called from a multithreaded application. All pppd versions released in the last 15 years just close() the file descriptor instead. Therefore, instead of hacking around this bug by exporting epoll internals to modules, and probably missing other related bugs, just remove the PPPIOCDETACH ioctl and see if anyone actually notices. Leave a stub in place that prints a one-time warning and returns EINVAL. Reported-by: syzbot+16363c99d4134717c05b@syzkaller.appspotmail.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Biggers Acked-by: Paul Mackerras Reviewed-by: Guillaume Nault Tested-by: Guillaume Nault Signed-off-by: David S. Miller

pppoe: check sockaddr length in pppoe_connect()

2018-04-24T01:12:15+00:00

We must validate sockaddr_len, otherwise userspace can pass fewer data than we expect and we end up accessing invalid data. Fixes: 224cf5ad14c0 ("ppp: Move the PPP drivers") Reported-by: syzbot+4f03bdf92fdf9ef5ddab@syzkaller.appspotmail.com Signed-off-by: Guillaume Nault Signed-off-by: David S. Miller

pptp: remove a buggy dst release in pptp_connect()

2018-04-04T15:17:55+00:00

Once dst has been cached in socket via sk_setup_caps(), it is illegal to call ip_rt_put() (or dst_release()), since sk_setup_caps() did not change dst refcount. We can still dereference it since we hold socket lock. Caugth by syzbot : BUG: KASAN: use-after-free in atomic_dec_return include/asm-generic/atomic-instrumented.h:198 [inline] BUG: KASAN: use-after-free in dst_release+0x27/0xa0 net/core/dst.c:185 Write of size 4 at addr ffff8801c54dc040 by task syz-executor4/20088 CPU: 1 PID: 20088 Comm: syz-executor4 Not tainted 4.16.0+ #376 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1a7/0x27d lib/dump_stack.c:53 print_address_description+0x73/0x250 mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report+0x23c/0x360 mm/kasan/report.c:412 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x137/0x190 mm/kasan/kasan.c:267 kasan_check_write+0x14/0x20 mm/kasan/kasan.c:278 atomic_dec_return include/asm-generic/atomic-instrumented.h:198 [inline] dst_release+0x27/0xa0 net/core/dst.c:185 sk_dst_set include/net/sock.h:1812 [inline] sk_dst_reset include/net/sock.h:1824 [inline] sock_setbindtodevice net/core/sock.c:610 [inline] sock_setsockopt+0x431/0x1b20 net/core/sock.c:707 SYSC_setsockopt net/socket.c:1845 [inline] SyS_setsockopt+0x2ff/0x360 net/socket.c:1828 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x4552d9 RSP: 002b:00007f4878126c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 00007f48781276d4 RCX: 00000000004552d9 RDX: 0000000000000019 RSI: 0000000000000001 RDI: 0000000000000013 RBP: 000000000072bea0 R08: 0000000000000010 R09: 0000000000000000 R10: 00000000200010c0 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000526 R14: 00000000006fac30 R15: 0000000000000000 Allocated by task 20088: save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:552 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3542 dst_alloc+0x11f/0x1a0 net/core/dst.c:104 rt_dst_alloc+0xe9/0x540 net/ipv4/route.c:1520 __mkroute_output net/ipv4/route.c:2265 [inline] ip_route_output_key_hash_rcu+0xa49/0x2c60 net/ipv4/route.c:2493 ip_route_output_key_hash+0x20b/0x370 net/ipv4/route.c:2322 __ip_route_output_key include/net/route.h:126 [inline] ip_route_output_flow+0x26/0xa0 net/ipv4/route.c:2577 ip_route_output_ports include/net/route.h:163 [inline] pptp_connect+0xa84/0x1170 drivers/net/ppp/pptp.c:453 SYSC_connect+0x213/0x4a0 net/socket.c:1639 SyS_connect+0x24/0x30 net/socket.c:1620 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 Freed by task 20082: save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527 __cache_free mm/slab.c:3486 [inline] kmem_cache_free+0x83/0x2a0 mm/slab.c:3744 dst_destroy+0x266/0x380 net/core/dst.c:140 dst_destroy_rcu+0x16/0x20 net/core/dst.c:153 __rcu_reclaim kernel/rcu/rcu.h:178 [inline] rcu_do_batch kernel/rcu/tree.c:2675 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:2930 [inline] __rcu_process_callbacks kernel/rcu/tree.c:2897 [inline] rcu_process_callbacks+0xd6c/0x17b0 kernel/rcu/tree.c:2914 __do_softirq+0x2d7/0xb85 kernel/softirq.c:285 The buggy address belongs to the object at ffff8801c54dc000 which belongs to the cache ip_dst_cache of size 168 The buggy address is located 64 bytes inside of 168-byte region [ffff8801c54dc000, ffff8801c54dc0a8) The buggy address belongs to the page: page:ffffea0007153700 count:1 mapcount:0 mapping:ffff8801c54dc000 index:0x0 flags: 0x2fffc0000000100(slab) raw: 02fffc0000000100 ffff8801c54dc000 0000000000000000 0000000100000010 raw: ffffea0006b34b20 ffffea0006b6c1e0 ffff8801d674a1c0 0000000000000000 page dumped because: kasan: bad access detected Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

net: Drop pernet_operations::async

2018-03-27T17:18:09+00:00

Synchronous pernet_operations are not allowed anymore. All are asynchronous. So, drop the structure member. Signed-off-by: Kirill Tkhai Signed-off-by: David S. Miller

drivers/net: Use octal not symbolic permissions

2018-03-26T16:07:49+00:00

Prefer the direct use of octal for permissions. Done with checkpatch -f --types=SYMBOLIC_PERMS --fix-inplace and some typing. Miscellanea: o Whitespace neatening around these conversions. Signed-off-by: Joe Perches Reviewed-by: Wei Liu Signed-off-by: David S. Miller

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

2018-03-23T15:31:58+00:00

Fun set of conflict resolutions here... For the mac80211 stuff, these were fortunately just parallel adds. Trivially resolved. In drivers/net/phy/phy.c we had a bug fix in 'net' that moved the function phy_disable_interrupts() earlier in the file, whilst in 'net-next' the phy_error() call from this function was removed. In net/ipv4/xfrm4_policy.c, David Ahern's changes to remove the 'rt_table_id' member of rtable collided with a bug fix in 'net' that added a new struct member "rt_mtu_locked" which needs to be copied over here. The mlxsw driver conflict consisted of net-next separating the span code and definitions into separate files, whilst a 'net' bug fix made some changes to that moved code. The mlx5 infiniband conflict resolution was quite non-trivial, the RDMA tree's merge commit was used as a guide here, and here are their notes: ==================== Due to bug fixes found by the syzkaller bot and taken into the for-rc branch after development for the 4.17 merge window had already started being taken into the for-next branch, there were fairly non-trivial merge issues that would need to be resolved between the for-rc branch and the for-next branch. This merge resolves those conflicts and provides a unified base upon which ongoing development for 4.17 can be based. Conflicts: drivers/infiniband/hw/mlx5/main.c - Commit 42cea83f9524 (IB/mlx5: Fix cleanup order on unload) added to for-rc and commit b5ca15ad7e61 (IB/mlx5: Add proper representors support) add as part of the devel cycle both needed to modify the init/de-init functions used by mlx5. To support the new representors, the new functions added by the cleanup patch needed to be made non-static, and the init/de-init list added by the representors patch needed to be modified to match the init/de-init list changes made by the cleanup patch. Updates: drivers/infiniband/hw/mlx5/mlx5_ib.h - Update function prototypes added by representors patch to reflect new function names as changed by cleanup patch drivers/infiniband/hw/mlx5/ib_rep.c - Update init/de-init stage list to match new order from cleanup patch ==================== Signed-off-by: David S. Miller

ppp: avoid loop in xmit recursion detection code

2018-03-22T16:35:18+00:00

We already detect situations where a PPP channel sends packets back to its upper PPP device. While this is enough to avoid deadlocking on xmit locks, this doesn't prevent packets from looping between the channel and the unit. The problem is that ppp_start_xmit() enqueues packets in ppp->file.xq before checking for xmit recursion. Therefore, __ppp_xmit_process() might dequeue a packet from ppp->file.xq and send it on the channel which, in turn, loops it back on the unit. Then ppp_start_xmit() queues the packet back to ppp->file.xq and __ppp_xmit_process() picks it up and sends it again through the channel. Therefore, the packet will loop between __ppp_xmit_process() and ppp_start_xmit() until some other part of the xmit path drops it. For L2TP, we rapidly fill the skb's headroom and pppol2tp_xmit() drops the packet after a few iterations. But PPTP reallocates the headroom if necessary, letting the loop run and exhaust the machine resources (as reported in https://bugzilla.kernel.org/show_bug.cgi?id=199109). Fix this by letting __ppp_xmit_process() enqueue the skb to ppp->file.xq, so that we can check for recursion before adding it to the queue. Now ppp_xmit_process() can drop the packet when recursion is detected. __ppp_channel_push() is a bit special. It calls __ppp_xmit_process() without having any actual packet to send. This is used by ppp_output_wakeup() to re-enable transmission on the parent unit (for implementations like ppp_async.c, where the .start_xmit() function might not consume the skb, leaving it in ppp->xmit_pending and disabling transmission). Therefore, __ppp_xmit_process() needs to handle the case where skb is NULL, dequeuing as many packets as possible from ppp->file.xq. Reported-by: xu heng Fixes: 55454a565836 ("ppp: avoid dealock on recursive xmit") Signed-off-by: Guillaume Nault Signed-off-by: David S. Miller

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

2018-03-06T06:20:46+00:00

All of the conflicts were cases of overlapping changes. In net/core/devlink.c, we have to make care that the resouce size_params have become a struct member rather than a pointer to such an object. Signed-off-by: David S. Miller

ppp: prevent unregistered channels from connecting to PPP units

2018-03-04T23:43:44+00:00

PPP units don't hold any reference on the channels connected to it. It is the channel's responsibility to ensure that it disconnects from its unit before being destroyed. In practice, this is ensured by ppp_unregister_channel() disconnecting the channel from the unit before dropping a reference on the channel. However, it is possible for an unregistered channel to connect to a PPP unit: register a channel with ppp_register_net_channel(), attach a /dev/ppp file to it with ioctl(PPPIOCATTCHAN), unregister the channel with ppp_unregister_channel() and finally connect the /dev/ppp file to a PPP unit with ioctl(PPPIOCCONNECT). Once in this situation, the channel is only held by the /dev/ppp file, which can be released at anytime and free the channel without letting the parent PPP unit know. Then the ppp structure ends up with dangling pointers in its ->channels list. Prevent this scenario by forbidding unregistered channels from connecting to PPP units. This maintains the code logic by keeping ppp_unregister_channel() responsible from disconnecting the channel if necessary and avoids modification on the reference counting mechanism. This issue seems to predate git history (successfully reproduced on Linux 2.6.26 and earlier PPP commits are unrelated). Signed-off-by: Guillaume Nault Signed-off-by: David S. Miller

net: Convert ppp_net_ops

2018-02-27T16:01:37+00:00

These pernet_operations are similar to bond_net_ops. Exit method unregisters all net ppp devices, and it looks like another pernet_operations are not interested in foreign net ppp list. So, it's possible to mark them async. Signed-off-by: Kirill Tkhai Signed-off-by: David S. Miller