kernel/drivers/net/ppp/ppp_generic.c, branch linux-4.1.y

ppp: prevent unregistered channels from connecting to PPP units

2018-03-21T03:49:49Z

[ Upstream commit 77f840e3e5f09c6d7d727e85e6e08276dd813d11 ] 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 Signed-off-by: Sasha Levin

ppp: Destroy the mutex when cleanup

2018-01-17T17:55:38Z

[ Upstream commit f02b2320b27c16b644691267ee3b5c110846f49e ] The mutex_destroy only makes sense when enable DEBUG_MUTEX. For the good readbility, it's better to invoke it in exit func when the init func invokes mutex_init. Signed-off-by: Gao Feng Acked-by: Guillaume Nault Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

ppp: take reference on channels netns

2016-07-11T03:07:05Z

[ Upstream commit 1f461dcdd296eecedaffffc6bae2bfa90bd7eb89 ] Let channels hold a reference on their network namespace. Some channel types, like ppp_async and ppp_synctty, can have their userspace controller running in a different namespace. Therefore they can't rely on them to preclude their netns from being removed from under them. ================================================================== BUG: KASAN: use-after-free in ppp_unregister_channel+0x372/0x3a0 at addr ffff880064e217e0 Read of size 8 by task syz-executor/11581 ============================================================================= BUG net_namespace (Not tainted): kasan: bad access detected ----------------------------------------------------------------------------- Disabling lock debugging due to kernel taint INFO: Allocated in copy_net_ns+0x6b/0x1a0 age=92569 cpu=3 pid=6906 [< none >] ___slab_alloc+0x4c7/0x500 kernel/mm/slub.c:2440 [< none >] __slab_alloc+0x4c/0x90 kernel/mm/slub.c:2469 [< inline >] slab_alloc_node kernel/mm/slub.c:2532 [< inline >] slab_alloc kernel/mm/slub.c:2574 [< none >] kmem_cache_alloc+0x23a/0x2b0 kernel/mm/slub.c:2579 [< inline >] kmem_cache_zalloc kernel/include/linux/slab.h:597 [< inline >] net_alloc kernel/net/core/net_namespace.c:325 [< none >] copy_net_ns+0x6b/0x1a0 kernel/net/core/net_namespace.c:360 [< none >] create_new_namespaces+0x2f6/0x610 kernel/kernel/nsproxy.c:95 [< none >] copy_namespaces+0x297/0x320 kernel/kernel/nsproxy.c:150 [< none >] copy_process.part.35+0x1bf4/0x5760 kernel/kernel/fork.c:1451 [< inline >] copy_process kernel/kernel/fork.c:1274 [< none >] _do_fork+0x1bc/0xcb0 kernel/kernel/fork.c:1723 [< inline >] SYSC_clone kernel/kernel/fork.c:1832 [< none >] SyS_clone+0x37/0x50 kernel/kernel/fork.c:1826 [< none >] entry_SYSCALL_64_fastpath+0x16/0x7a kernel/arch/x86/entry/entry_64.S:185 INFO: Freed in net_drop_ns+0x67/0x80 age=575 cpu=2 pid=2631 [< none >] __slab_free+0x1fc/0x320 kernel/mm/slub.c:2650 [< inline >] slab_free kernel/mm/slub.c:2805 [< none >] kmem_cache_free+0x2a0/0x330 kernel/mm/slub.c:2814 [< inline >] net_free kernel/net/core/net_namespace.c:341 [< none >] net_drop_ns+0x67/0x80 kernel/net/core/net_namespace.c:348 [< none >] cleanup_net+0x4e5/0x600 kernel/net/core/net_namespace.c:448 [< none >] process_one_work+0x794/0x1440 kernel/kernel/workqueue.c:2036 [< none >] worker_thread+0xdb/0xfc0 kernel/kernel/workqueue.c:2170 [< none >] kthread+0x23f/0x2d0 kernel/drivers/block/aoe/aoecmd.c:1303 [< none >] ret_from_fork+0x3f/0x70 kernel/arch/x86/entry/entry_64.S:468 INFO: Slab 0xffffea0001938800 objects=3 used=0 fp=0xffff880064e20000 flags=0x5fffc0000004080 INFO: Object 0xffff880064e20000 @offset=0 fp=0xffff880064e24200 CPU: 1 PID: 11581 Comm: syz-executor Tainted: G B 4.4.0+ Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.8.2-0-g33fbe13 by qemu-project.org 04/01/2014 00000000ffffffff ffff8800662c7790 ffffffff8292049d ffff88003e36a300 ffff880064e20000 ffff880064e20000 ffff8800662c77c0 ffffffff816f2054 ffff88003e36a300 ffffea0001938800 ffff880064e20000 0000000000000000 Call Trace: [< inline >] __dump_stack kernel/lib/dump_stack.c:15 [] dump_stack+0x6f/0xa2 kernel/lib/dump_stack.c:50 [] print_trailer+0xf4/0x150 kernel/mm/slub.c:654 [] object_err+0x2f/0x40 kernel/mm/slub.c:661 [< inline >] print_address_description kernel/mm/kasan/report.c:138 [] kasan_report_error+0x215/0x530 kernel/mm/kasan/report.c:236 [< inline >] kasan_report kernel/mm/kasan/report.c:259 [] __asan_report_load8_noabort+0x3e/0x40 kernel/mm/kasan/report.c:280 [< inline >] ? ppp_pernet kernel/include/linux/compiler.h:218 [] ? ppp_unregister_channel+0x372/0x3a0 kernel/drivers/net/ppp/ppp_generic.c:2392 [< inline >] ppp_pernet kernel/include/linux/compiler.h:218 [] ppp_unregister_channel+0x372/0x3a0 kernel/drivers/net/ppp/ppp_generic.c:2392 [< inline >] ? ppp_pernet kernel/drivers/net/ppp/ppp_generic.c:293 [] ? ppp_unregister_channel+0xe6/0x3a0 kernel/drivers/net/ppp/ppp_generic.c:2392 [] ppp_asynctty_close+0xa3/0x130 kernel/drivers/net/ppp/ppp_async.c:241 [] ? async_lcp_peek+0x5b0/0x5b0 kernel/drivers/net/ppp/ppp_async.c:1000 [] tty_ldisc_close.isra.1+0x99/0xe0 kernel/drivers/tty/tty_ldisc.c:478 [] tty_ldisc_kill+0x40/0x170 kernel/drivers/tty/tty_ldisc.c:744 [] tty_ldisc_release+0x1b3/0x260 kernel/drivers/tty/tty_ldisc.c:772 [] tty_release+0xac1/0x13e0 kernel/drivers/tty/tty_io.c:1901 [] ? release_tty+0x320/0x320 kernel/drivers/tty/tty_io.c:1688 [] __fput+0x236/0x780 kernel/fs/file_table.c:208 [] ____fput+0x15/0x20 kernel/fs/file_table.c:244 [] task_work_run+0x16b/0x200 kernel/kernel/task_work.c:115 [< inline >] exit_task_work kernel/include/linux/task_work.h:21 [] do_exit+0x8b5/0x2c60 kernel/kernel/exit.c:750 [] ? debug_check_no_locks_freed+0x290/0x290 kernel/kernel/locking/lockdep.c:4123 [] ? mm_update_next_owner+0x6f0/0x6f0 kernel/kernel/exit.c:357 [] ? __dequeue_signal+0x136/0x470 kernel/kernel/signal.c:550 [] ? recalc_sigpending_tsk+0x13b/0x180 kernel/kernel/signal.c:145 [] do_group_exit+0x108/0x330 kernel/kernel/exit.c:880 [] get_signal+0x5e4/0x14f0 kernel/kernel/signal.c:2307 [< inline >] ? kretprobe_table_lock kernel/kernel/kprobes.c:1113 [] ? kprobe_flush_task+0xb5/0x450 kernel/kernel/kprobes.c:1158 [] do_signal+0x83/0x1c90 kernel/arch/x86/kernel/signal.c:712 [] ? recycle_rp_inst+0x310/0x310 kernel/include/linux/list.h:655 [] ? setup_sigcontext+0x780/0x780 kernel/arch/x86/kernel/signal.c:165 [] ? finish_task_switch+0x424/0x5f0 kernel/kernel/sched/core.c:2692 [< inline >] ? finish_lock_switch kernel/kernel/sched/sched.h:1099 [] ? finish_task_switch+0x120/0x5f0 kernel/kernel/sched/core.c:2678 [< inline >] ? context_switch kernel/kernel/sched/core.c:2807 [] ? __schedule+0x919/0x1bd0 kernel/kernel/sched/core.c:3283 [] exit_to_usermode_loop+0xf1/0x1a0 kernel/arch/x86/entry/common.c:247 [< inline >] prepare_exit_to_usermode kernel/arch/x86/entry/common.c:282 [] syscall_return_slowpath+0x19f/0x210 kernel/arch/x86/entry/common.c:344 [] int_ret_from_sys_call+0x25/0x9f kernel/arch/x86/entry/entry_64.S:281 Memory state around the buggy address: ffff880064e21680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff880064e21700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff880064e21780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff880064e21800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff880064e21880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Fixes: 273ec51dd7ce ("net: ppp_generic - introduce net-namespace functionality v2") Reported-by: Baozeng Ding Signed-off-by: Guillaume Nault Reviewed-by: Cyrill Gorcunov Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

ppp: ensure file->private_data can't be overridden

2016-07-11T03:07:04Z

[ Upstream commit e8e56ffd9d2973398b60ece1f1bebb8d67b4d032 ] Locking ppp_mutex must be done before dereferencing file->private_data, otherwise it could be modified before ppp_unattached_ioctl() takes the lock. This could lead ppp_unattached_ioctl() to override ->private_data, thus leaking reference to the ppp_file previously pointed to. v2: lock all ppp_ioctl() instead of just checking private_data in ppp_unattached_ioctl(), to avoid ambiguous behaviour. Fixes: f3ff8a4d80e8 ("ppp: push BKL down into the driver") Signed-off-by: Guillaume Nault Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

ppp, slip: Validate VJ compression slot parameters completely

2016-01-31T19:23:37Z

[ Upstream commit 4ab42d78e37a294ac7bc56901d563c642e03c4ae ] Currently slhc_init() treats out-of-range values of rslots and tslots as equivalent to 0, except that if tslots is too large it will dereference a null pointer (CVE-2015-7799). Add a range-check at the top of the function and make it return an ERR_PTR() on error instead of NULL. Change the callers accordingly. Compile-tested only. Reported-by: 郭永刚 References: http://article.gmane.org/gmane.comp.security.oss.general/17908 Signed-off-by: Ben Hutchings Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

ppp: call skb_checksum_complete_unset in ppp_receive_frame

2015-04-21T01:57:26Z

Call checksum_complete_unset in PPP receive to discard checksum-complete value. PPP does not pull checksum for headers and also modifies packet as in VJ compression. Signed-off-by: Tom Herbert Signed-off-by: David S. Miller

ppp_read(): switch to skb_copy_datagram_iter()

2014-12-09T21:29:10Z

Signed-off-by: Al Viro

net: ppp: Don't call bpf_prog_create() in ppp_lock

2014-11-11T20:15:03Z

In ppp_ioctl(), bpf_prog_create() is called inside ppp_lock, which eventually calls vmalloc() and hits BUG_ON() in vmalloc.c. This patch works around the problem by moving the allocation outside the lock. The bug was revealed by the recent change in net/core/filter.c, as it allocates via vmalloc() instead of kmalloc() now. Reported-and-tested-by: Stefan Seyfried Signed-off-by: Takashi Iwai Signed-off-by: David S. Miller

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2014-10-13T09:28:42Z

Pull vfs updates from Al Viro: "The big thing in this pile is Eric's unmount-on-rmdir series; we finally have everything we need for that. The final piece of prereqs is delayed mntput() - now filesystem shutdown always happens on shallow stack. Other than that, we have several new primitives for iov_iter (Matt Wilcox, culled from his XIP-related series) pushing the conversion to ->read_iter()/ ->write_iter() a bit more, a bunch of fs/dcache.c cleanups and fixes (including the external name refcounting, which gives consistent behaviour of d_move() wrt procfs symlinks for long and short names alike) and assorted cleanups and fixes all over the place. This is just the first pile; there's a lot of stuff from various people that ought to go in this window. Starting with unionmount/overlayfs mess... ;-/" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (60 commits) fs/file_table.c: Update alloc_file() comment vfs: Deduplicate code shared by xattr system calls operating on paths reiserfs: remove pointless forward declaration of struct nameidata don't need that forward declaration of struct nameidata in dcache.h anymore take dname_external() into fs/dcache.c let path_init() failures treated the same way as subsequent link_path_walk() fix misuses of f_count() in ppp and netlink ncpfs: use list_for_each_entry() for d_subdirs walk vfs: move getname() from callers to do_mount() gfs2_atomic_open(): skip lookups on hashed dentry [infiniband] remove pointless assignments gadgetfs: saner API for gadgetfs_create_file() f_fs: saner API for ffs_sb_create_file() jfs: don't hash direct inode [s390] remove pointless assignment of ->f_op in vmlogrdr ->open() ecryptfs: ->f_op is never NULL android: ->f_op is never NULL nouveau: __iomem misannotations missing annotation in fs/file.c fs: namespace: suppress 'may be used uninitialized' warnings ...

fix misuses of f_count() in ppp and netlink

2014-10-09T06:39:17Z

we used to check for "nobody else could start doing anything with that opened file" by checking that refcount was 2 or less - one for descriptor table and one we'd acquired in fget() on the way to wherever we are. That was race-prone (somebody else might have had a reference to descriptor table and do fget() just as we'd been checking) and it had become flat-out incorrect back when we switched to fget_light() on those codepaths - unlike fget(), it doesn't grab an extra reference unless the descriptor table is shared. The same change allowed a race-free check, though - we are safe exactly when refcount is less than 2. It was a long time ago; pre-2.6.12 for ioctl() (the codepath leading to ppp one) and 2.6.17 for sendmsg() (netlink one). OTOH, netlink hadn't grown that check until 3.9 and ppp used to live in drivers/net, not drivers/net/ppp until 3.1. The bug existed well before that, though, and the same fix used to apply in old location of file. Cc: stable@vger.kernel.org Signed-off-by: Al Viro