[Patch attached] Secure TCP timestamp response #50

theLOICofFRANCE · 2017-08-07T14:05:34Z

Hi,

The pentesters use the TCP timestamp response for fingerprinted based on the behavior and to find the remote host's uptime.

I suggest you change the default value (which should slightly increase the performance).

tcp_timestamps_secure.txt

This is a simple alternative to Brad's "random_timestamp.diff" patch.

Thanks.

thestinger · 2017-08-07T16:13:27Z

Modern Linux kernels use a per-connection random base for the timestamps:

torvalds/linux@95a22ca

The main issue (TCP timestamps) is resolved in a generic way.

theLOICofFRANCE · 2017-08-11T12:34:47Z

Great, I hadn't seen it.

Increase kasan instrumented kernel stack size from 32k to 64k. Other architectures seems to get away with just doubling kernel stack size under kasan, but on s390 this appears to be not enough due to bigger frame size. The particular pain point is kasan inlined checks (CONFIG_KASAN_INLINE vs CONFIG_KASAN_OUTLINE). With inlined checks one particular case hitting stack overflow is fs sync on xfs filesystem: #0 [9a0681e8] 704 bytes check_usage at 34b1fc GrapheneOS#1 [9a0684a8] 432 bytes check_usage at 34c710 GrapheneOS#2 [9a068658] 1048 bytes validate_chain at 35044a GrapheneOS#3 [9a068a70] 312 bytes __lock_acquire at 3559fe GrapheneOS#4 [9a068ba8] 440 bytes lock_acquire at 3576ee GrapheneOS#5 [9a068d60] 104 bytes _raw_spin_lock at 21b44e0 GrapheneOS#6 [9a068dc8] 1992 bytes enqueue_entity at 2dbf72 GrapheneOS#7 [9a069590] 1496 bytes enqueue_task_fair at 2df5f0 GrapheneOS#8 [9a069b68] 64 bytes ttwu_do_activate at 28f438 GrapheneOS#9 [9a069ba8] 552 bytes try_to_wake_up at 298c4c GrapheneOS#10 [9a069dd0] 168 bytes wake_up_worker at 23f97c GrapheneOS#11 [9a069e78] 200 bytes insert_work at 23fc2e GrapheneOS#12 [9a069f40] 648 bytes __queue_work at 2487c0 GrapheneOS#13 [9a06a1c8] 200 bytes __queue_delayed_work at 24db28 GrapheneOS#14 [9a06a290] 248 bytes mod_delayed_work_on at 24de84 GrapheneOS#15 [9a06a388] 24 bytes kblockd_mod_delayed_work_on at 153e2a0 GrapheneOS#16 [9a06a3a0] 288 bytes __blk_mq_delay_run_hw_queue at 158168c GrapheneOS#17 [9a06a4c0] 192 bytes blk_mq_run_hw_queue at 1581a3c GrapheneOS#18 [9a06a580] 184 bytes blk_mq_sched_insert_requests at 15a2192 GrapheneOS#19 [9a06a638] 1024 bytes blk_mq_flush_plug_list at 1590f3a GrapheneOS#20 [9a06aa38] 704 bytes blk_flush_plug_list at 1555028 GrapheneOS#21 [9a06acf8] 320 bytes schedule at 219e476 GrapheneOS#22 [9a06ae38] 760 bytes schedule_timeout at 21b0aac GrapheneOS#23 [9a06b130] 408 bytes wait_for_common at 21a1706 GrapheneOS#24 [9a06b2c8] 360 bytes xfs_buf_iowait at fa1540 GrapheneOS#25 [9a06b430] 256 bytes __xfs_buf_submit at fadae6 GrapheneOS#26 [9a06b530] 264 bytes xfs_buf_read_map at fae3f6 GrapheneOS#27 [9a06b638] 656 bytes xfs_trans_read_buf_map at 10ac9a8 GrapheneOS#28 [9a06b8c8] 304 bytes xfs_btree_kill_root at e72426 GrapheneOS#29 [9a06b9f8] 288 bytes xfs_btree_lookup_get_block at e7bc5e GrapheneOS#30 [9a06bb18] 624 bytes xfs_btree_lookup at e7e1a6 GrapheneOS#31 [9a06bd88] 2664 bytes xfs_alloc_ag_vextent_near at dfa070 GrapheneOS#32 [9a06c7f0] 144 bytes xfs_alloc_ag_vextent at dff3ca GrapheneOS#33 [9a06c880] 1128 bytes xfs_alloc_vextent at e05fce GrapheneOS#34 [9a06cce8] 584 bytes xfs_bmap_btalloc at e58342 GrapheneOS#35 [9a06cf30] 1336 bytes xfs_bmapi_write at e618de GrapheneOS#36 [9a06d468] 776 bytes xfs_iomap_write_allocate at ff678e GrapheneOS#37 [9a06d770] 720 bytes xfs_map_blocks at f82af8 GrapheneOS#38 [9a06da40] 928 bytes xfs_writepage_map at f83cd6 GrapheneOS#39 [9a06dde0] 320 bytes xfs_do_writepage at f85872 GrapheneOS#40 [9a06df20] 1320 bytes write_cache_pages at 73dfe8 GrapheneOS#41 [9a06e448] 208 bytes xfs_vm_writepages at f7f892 GrapheneOS#42 [9a06e518] 88 bytes do_writepages at 73fe6a GrapheneOS#43 [9a06e570] 872 bytes __writeback_single_inode at a20cb6 GrapheneOS#44 [9a06e8d8] 664 bytes writeback_sb_inodes at a23be2 GrapheneOS#45 [9a06eb70] 296 bytes __writeback_inodes_wb at a242e0 GrapheneOS#46 [9a06ec98] 928 bytes wb_writeback at a2500e GrapheneOS#47 [9a06f038] 848 bytes wb_do_writeback at a260ae GrapheneOS#48 [9a06f388] 536 bytes wb_workfn at a28228 GrapheneOS#49 [9a06f5a0] 1088 bytes process_one_work at 24a234 GrapheneOS#50 [9a06f9e0] 1120 bytes worker_thread at 24ba26 GrapheneOS#51 [9a06fe40] 104 bytes kthread at 26545a GrapheneOS#52 [9a06fea8] kernel_thread_starter at 21b6b62 To be able to increase the stack size to 64k reuse LLILL instruction in __switch_to function to load 64k - STACK_FRAME_OVERHEAD - __PT_SIZE (65192) value as unsigned. Reported-by: Benjamin Block <bblock@linux.ibm.com> Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[ Upstream commit 388b4e6 ] scsi_device_quiesce() and scsi_device_resume() are called during system-wide suspend and resume. scsi_device_quiesce() only succeeds for SCSI devices that are in one of the RUNNING, OFFLINE or TRANSPORT_OFFLINE states (see also scsi_set_device_state()). This patch avoids that the following warning is triggered when resuming a system for which quiescing a SCSI device failed: WARNING: CPU: 2 PID: 11303 at drivers/scsi/scsi_lib.c:2600 scsi_device_resume+0x4f/0x58 CPU: 2 PID: 11303 Comm: kworker/u8:70 Not tainted 5.0.0-rc1+ #50 Hardware name: LENOVO 80E3/Lancer 5B2, BIOS A2CN45WW(V2.13) 08/04/2016 Workqueue: events_unbound async_run_entry_fn Call Trace: scsi_dev_type_resume+0x2e/0x60 async_run_entry_fn+0x32/0xd8 process_one_work+0x1f4/0x420 worker_thread+0x28/0x3c0 kthread+0x118/0x130 ret_from_fork+0x22/0x40 Cc: Przemek Socha <soprwa@gmail.com> Reported-by: Przemek Socha <soprwa@gmail.com> Fixes: 3a0a529 ("block, scsi: Make SCSI quiesce and resume work reliably") # v4.15 Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit 3f167e1 ] ipv4_pdp_add() is called in RCU read-side critical section. So GFP_KERNEL should not be used in the function. This patch make ipv4_pdp_add() to use GFP_ATOMIC instead of GFP_KERNEL. Test commands: gtp-link add gtp1 & gtp-tunnel add gtp1 v1 100 200 1.1.1.1 2.2.2.2 Splat looks like: [ 130.618881] ============================= [ 130.626382] WARNING: suspicious RCU usage [ 130.626994] 5.2.0-rc6+ #50 Not tainted [ 130.627622] ----------------------------- [ 130.628223] ./include/linux/rcupdate.h:266 Illegal context switch in RCU read-side critical section! [ 130.629684] [ 130.629684] other info that might help us debug this: [ 130.629684] [ 130.631022] [ 130.631022] rcu_scheduler_active = 2, debug_locks = 1 [ 130.632136] 4 locks held by gtp-tunnel/1025: [ 130.632925] #0: 000000002b93c8b7 (cb_lock){++++}, at: genl_rcv+0x15/0x40 [ 130.634159] #1: 00000000f17bc999 (genl_mutex){+.+.}, at: genl_rcv_msg+0xfb/0x130 [ 130.635487] #2: 00000000c644ed8e (rtnl_mutex){+.+.}, at: gtp_genl_new_pdp+0x18c/0x1150 [gtp] [ 130.636936] #3: 0000000007a1cde7 (rcu_read_lock){....}, at: gtp_genl_new_pdp+0x187/0x1150 [gtp] [ 130.638348] [ 130.638348] stack backtrace: [ 130.639062] CPU: 1 PID: 1025 Comm: gtp-tunnel Not tainted 5.2.0-rc6+ #50 [ 130.641318] Call Trace: [ 130.641707] dump_stack+0x7c/0xbb [ 130.642252] ___might_sleep+0x2c0/0x3b0 [ 130.642862] kmem_cache_alloc_trace+0x1cd/0x2b0 [ 130.643591] gtp_genl_new_pdp+0x6c5/0x1150 [gtp] [ 130.644371] genl_family_rcv_msg+0x63a/0x1030 [ 130.645074] ? mutex_lock_io_nested+0x1090/0x1090 [ 130.645845] ? genl_unregister_family+0x630/0x630 [ 130.646592] ? debug_show_all_locks+0x2d0/0x2d0 [ 130.647293] ? check_flags.part.40+0x440/0x440 [ 130.648099] genl_rcv_msg+0xa3/0x130 [ ... ] Fixes: 459aa66 ("gtp: add initial driver for datapath of GPRS Tunneling Protocol (GTP-U)") Signed-off-by: Taehee Yoo <ap420073@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit 1788b85 ] gtp_encap_destroy() is called twice. 1. When interface is deleted. 2. When udp socket is destroyed. either gtp->sk0 or gtp->sk1u could be freed by sock_put() in gtp_encap_destroy(). so, when gtp_encap_destroy() is called again, it would uses freed sk pointer. patch makes gtp_encap_destroy() to set either gtp->sk0 or gtp->sk1u to null. in addition, both gtp->sk0 and gtp->sk1u pointer are protected by rtnl_lock. so, rtnl_lock() is added. Test command: gtp-link add gtp1 & killall gtp-link ip link del gtp1 Splat looks like: [ 83.182767] BUG: KASAN: use-after-free in __lock_acquire+0x3a20/0x46a0 [ 83.184128] Read of size 8 at addr ffff8880cc7d5360 by task ip/1008 [ 83.185567] CPU: 1 PID: 1008 Comm: ip Not tainted 5.2.0-rc6+ #50 [ 83.188469] Call Trace: [ ... ] [ 83.200126] lock_acquire+0x141/0x380 [ 83.200575] ? lock_sock_nested+0x3a/0xf0 [ 83.201069] _raw_spin_lock_bh+0x38/0x70 [ 83.201551] ? lock_sock_nested+0x3a/0xf0 [ 83.202044] lock_sock_nested+0x3a/0xf0 [ 83.202520] gtp_encap_destroy+0x18/0xe0 [gtp] [ 83.203065] gtp_encap_disable.isra.14+0x13/0x50 [gtp] [ 83.203687] gtp_dellink+0x56/0x170 [gtp] [ 83.204190] rtnl_delete_link+0xb4/0x100 [ ... ] [ 83.236513] Allocated by task 976: [ 83.236925] save_stack+0x19/0x80 [ 83.237332] __kasan_kmalloc.constprop.3+0xa0/0xd0 [ 83.237894] kmem_cache_alloc+0xd8/0x280 [ 83.238360] sk_prot_alloc.isra.42+0x50/0x200 [ 83.238874] sk_alloc+0x32/0x940 [ 83.239264] inet_create+0x283/0xc20 [ 83.239684] __sock_create+0x2dd/0x540 [ 83.240136] __sys_socket+0xca/0x1a0 [ 83.240550] __x64_sys_socket+0x6f/0xb0 [ 83.240998] do_syscall_64+0x9c/0x450 [ 83.241466] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 83.242061] [ 83.242249] Freed by task 0: [ 83.242616] save_stack+0x19/0x80 [ 83.243013] __kasan_slab_free+0x111/0x150 [ 83.243498] kmem_cache_free+0x89/0x250 [ 83.244444] __sk_destruct+0x38f/0x5a0 [ 83.245366] rcu_core+0x7e9/0x1c20 [ 83.245766] __do_softirq+0x213/0x8fa Fixes: 1e3a3ab ("gtp: make GTP sockets in gtp_newlink optional") Signed-off-by: Taehee Yoo <ap420073@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit a2bed90 ] Current gtp_newlink() could be called after unregister_pernet_subsys(). gtp_newlink() uses gtp_net but it can be destroyed by unregister_pernet_subsys(). So unregister_pernet_subsys() should be called after rtnl_link_unregister(). Test commands: #SHELL 1 while : do for i in {1..5} do ./gtp-link add gtp$i & done killall gtp-link done #SHELL 2 while : do modprobe -rv gtp done Splat looks like: [ 753.176631] BUG: KASAN: use-after-free in gtp_newlink+0x9b4/0xa5c [gtp] [ 753.177722] Read of size 8 at addr ffff8880d48f2458 by task gtp-link/7126 [ 753.179082] CPU: 0 PID: 7126 Comm: gtp-link Tainted: G W 5.2.0-rc6+ #50 [ 753.185801] Call Trace: [ 753.186264] dump_stack+0x7c/0xbb [ 753.186863] ? gtp_newlink+0x9b4/0xa5c [gtp] [ 753.187583] print_address_description+0xc7/0x240 [ 753.188382] ? gtp_newlink+0x9b4/0xa5c [gtp] [ 753.189097] ? gtp_newlink+0x9b4/0xa5c [gtp] [ 753.189846] __kasan_report+0x12a/0x16f [ 753.190542] ? gtp_newlink+0x9b4/0xa5c [gtp] [ 753.191298] kasan_report+0xe/0x20 [ 753.191893] gtp_newlink+0x9b4/0xa5c [gtp] [ 753.192580] ? __netlink_ns_capable+0xc3/0xf0 [ 753.193370] __rtnl_newlink+0xb9f/0x11b0 [ ... ] [ 753.241201] Allocated by task 7186: [ 753.241844] save_stack+0x19/0x80 [ 753.242399] __kasan_kmalloc.constprop.3+0xa0/0xd0 [ 753.243192] __kmalloc+0x13e/0x300 [ 753.243764] ops_init+0xd6/0x350 [ 753.244314] register_pernet_operations+0x249/0x6f0 [ ... ] [ 753.251770] Freed by task 7178: [ 753.252288] save_stack+0x19/0x80 [ 753.252833] __kasan_slab_free+0x111/0x150 [ 753.253962] kfree+0xc7/0x280 [ 753.254509] ops_free_list.part.11+0x1c4/0x2d0 [ 753.255241] unregister_pernet_operations+0x262/0x390 [ ... ] [ 753.285883] list_add corruption. next->prev should be prev (ffff8880d48f2458), but was ffff8880d497d878. (next. [ 753.287241] ------------[ cut here ]------------ [ 753.287794] kernel BUG at lib/list_debug.c:25! [ 753.288364] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI [ 753.289099] CPU: 0 PID: 7126 Comm: gtp-link Tainted: G B W 5.2.0-rc6+ #50 [ 753.291036] RIP: 0010:__list_add_valid+0x74/0xd0 [ 753.291589] Code: 48 39 da 75 27 48 39 f5 74 36 48 39 dd 74 31 48 83 c4 08 b8 01 00 00 00 5b 5d c3 48 89 d9 48b [ 753.293779] RSP: 0018:ffff8880cae8f398 EFLAGS: 00010286 [ 753.294401] RAX: 0000000000000075 RBX: ffff8880d497d878 RCX: 0000000000000000 [ 753.296260] RDX: 0000000000000075 RSI: 0000000000000008 RDI: ffffed10195d1e69 [ 753.297070] RBP: ffff8880cd250ae0 R08: ffffed101b4bff21 R09: ffffed101b4bff21 [ 753.297899] R10: 0000000000000001 R11: ffffed101b4bff20 R12: ffff8880d497d878 [ 753.298703] R13: 0000000000000000 R14: ffff8880cd250ae0 R15: ffff8880d48f2458 [ 753.299564] FS: 00007f5f79805740(0000) GS:ffff8880da400000(0000) knlGS:0000000000000000 [ 753.300533] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 753.301231] CR2: 00007fe8c7ef4f10 CR3: 00000000b71a6006 CR4: 00000000000606f0 [ 753.302183] Call Trace: [ 753.302530] gtp_newlink+0x5f6/0xa5c [gtp] [ 753.303037] ? __netlink_ns_capable+0xc3/0xf0 [ 753.303576] __rtnl_newlink+0xb9f/0x11b0 [ 753.304092] ? rtnl_link_unregister+0x230/0x230 Fixes: 459aa66 ("gtp: add initial driver for datapath of GPRS Tunneling Protocol (GTP-U)") Signed-off-by: Taehee Yoo <ap420073@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org>