pm24.git/include/linux/bpfilter.h, branch v5.2-rc2

net: bpfilter: disallow to remove bpfilter module while being used

2019-01-12T02:05:41Z

The bpfilter.ko module can be removed while functions of the bpfilter.ko are executing. so panic can occurred. in order to protect that, locks can be used. a bpfilter_lock protects routines in the __bpfilter_process_sockopt() but it's not enough because __exit routine can be executed concurrently. Now, the bpfilter_umh can not run in parallel. So, the module do not removed while it's being used and it do not double-create UMH process. The members of the umh_info and the bpfilter_umh_ops are protected by the bpfilter_umh_ops.lock. test commands: while : do iptables -I FORWARD -m string --string ap --algo kmp & modprobe -rv bpfilter & done splat looks like: [ 298.623435] BUG: unable to handle kernel paging request at fffffbfff807440b [ 298.628512] #PF error: [normal kernel read fault] [ 298.633018] PGD 124327067 P4D 124327067 PUD 11c1a3067 PMD 119eb2067 PTE 0 [ 298.638859] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI [ 298.638859] CPU: 0 PID: 2997 Comm: iptables Not tainted 4.20.0+ #154 [ 298.638859] RIP: 0010:__mutex_lock+0x6b9/0x16a0 [ 298.638859] Code: c0 00 00 e8 89 82 ff ff 80 bd 8f fc ff ff 00 0f 85 d9 05 00 00 48 8b 85 80 fc ff ff 48 bf 00 00 00 00 00 fc ff df 48 c1 e8 03 <80> 3c 38 00 0f 85 1d 0e 00 00 48 8b 85 c8 fc ff ff 49 39 47 58 c6 [ 298.638859] RSP: 0018:ffff88810e7777a0 EFLAGS: 00010202 [ 298.638859] RAX: 1ffffffff807440b RBX: ffff888111bd4d80 RCX: 0000000000000000 [ 298.638859] RDX: 1ffff110235ff806 RSI: ffff888111bd5538 RDI: dffffc0000000000 [ 298.638859] RBP: ffff88810e777b30 R08: 0000000080000002 R09: 0000000000000000 [ 298.638859] R10: 0000000000000000 R11: 0000000000000000 R12: fffffbfff168a42c [ 298.638859] R13: ffff888111bd4d80 R14: ffff8881040e9a05 R15: ffffffffc03a2000 [ 298.638859] FS: 00007f39e3758700(0000) GS:ffff88811ae00000(0000) knlGS:0000000000000000 [ 298.638859] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 298.638859] CR2: fffffbfff807440b CR3: 000000011243e000 CR4: 00000000001006f0 [ 298.638859] Call Trace: [ 298.638859] ? mutex_lock_io_nested+0x1560/0x1560 [ 298.638859] ? kasan_kmalloc+0xa0/0xd0 [ 298.638859] ? kmem_cache_alloc+0x1c2/0x260 [ 298.638859] ? __alloc_file+0x92/0x3c0 [ 298.638859] ? alloc_empty_file+0x43/0x120 [ 298.638859] ? alloc_file_pseudo+0x220/0x330 [ 298.638859] ? sock_alloc_file+0x39/0x160 [ 298.638859] ? __sys_socket+0x113/0x1d0 [ 298.638859] ? __x64_sys_socket+0x6f/0xb0 [ 298.638859] ? do_syscall_64+0x138/0x560 [ 298.638859] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 298.638859] ? __alloc_file+0x92/0x3c0 [ 298.638859] ? init_object+0x6b/0x80 [ 298.638859] ? cyc2ns_read_end+0x10/0x10 [ 298.638859] ? cyc2ns_read_end+0x10/0x10 [ 298.638859] ? hlock_class+0x140/0x140 [ 298.638859] ? sched_clock_local+0xd4/0x140 [ 298.638859] ? sched_clock_local+0xd4/0x140 [ 298.638859] ? check_flags.part.37+0x440/0x440 [ 298.638859] ? __lock_acquire+0x4f90/0x4f90 [ 298.638859] ? set_rq_offline.part.89+0x140/0x140 [ ... ] Fixes: d2ba09c17a06 ("net: add skeleton of bpfilter kernel module") Signed-off-by: Taehee Yoo Signed-off-by: David S. Miller

net: bpfilter: restart bpfilter_umh when error occurred

2019-01-12T02:05:41Z

The bpfilter_umh will be stopped via __stop_umh() when the bpfilter error occurred. The bpfilter_umh() couldn't start again because there is no restart routine. The section of the bpfilter_umh_{start/end} is no longer .init.rodata because these area should be reused in the restart routine. hence the section name is changed to .bpfilter_umh. The bpfilter_ops->start() is restart callback. it will be called when bpfilter_umh is stopped. The stop bit means bpfilter_umh is stopped. this bit is set by both start and stop routine. Before this patch, Test commands: $ iptables -vnL $ kill -9 $ iptables -vnL [ 480.045136] bpfilter: write fail -32 $ iptables -vnL All iptables commands will fail. After this patch, Test commands: $ iptables -vnL $ kill -9 $ iptables -vnL $ iptables -vnL Now, all iptables commands will work. Fixes: d2ba09c17a06 ("net: add skeleton of bpfilter kernel module") Signed-off-by: Taehee Yoo Signed-off-by: David S. Miller

net: bpfilter: use cleanup callback to release umh_info

2019-01-12T02:05:41Z

Now, UMH process is killed, do_exit() calls the umh_info->cleanup callback to release members of the umh_info. This patch makes bpfilter_umh's cleanup routine to use the umh_info->cleanup callback. Signed-off-by: Taehee Yoo Signed-off-by: David S. Miller

bpfilter: Fix mismatch in function argument types

2018-07-21T23:21:25Z

Fix following warning: net/ipv4/bpfilter/sockopt.c:28:5: error: symbol 'bpfilter_ip_set_sockopt' redeclared with different type net/ipv4/bpfilter/sockopt.c:34:5: error: symbol 'bpfilter_ip_get_sockopt' redeclared with different type Signed-off-by: YueHaibing Acked-by: Martin KaFai Lau Acked-by: Daniel Borkmann Signed-off-by: David S. Miller

net: add skeleton of bpfilter kernel module

2018-05-23T17:23:40Z

bpfilter.ko consists of bpfilter_kern.c (normal kernel module code) and user mode helper code that is embedded into bpfilter.ko The steps to build bpfilter.ko are the following: - main.c is compiled by HOSTCC into the bpfilter_umh elf executable file - with quite a bit of objcopy and Makefile magic the bpfilter_umh elf file is converted into bpfilter_umh.o object file with _binary_net_bpfilter_bpfilter_umh_start and _end symbols Example: $ nm ./bld_x64/net/bpfilter/bpfilter_umh.o 0000000000004cf8 T _binary_net_bpfilter_bpfilter_umh_end 0000000000004cf8 A _binary_net_bpfilter_bpfilter_umh_size 0000000000000000 T _binary_net_bpfilter_bpfilter_umh_start - bpfilter_umh.o and bpfilter_kern.o are linked together into bpfilter.ko bpfilter_kern.c is a normal kernel module code that calls the fork_usermode_blob() helper to execute part of its own data as a user mode process. Notice that _binary_net_bpfilter_bpfilter_umh_start - end is placed into .init.rodata section, so it's freed as soon as __init function of bpfilter.ko is finished. As part of __init the bpfilter.ko does first request/reply action via two unix pipe provided by fork_usermode_blob() helper to make sure that umh is healthy. If not it will kill it via pid. Later bpfilter_process_sockopt() will be called from bpfilter hooks in get/setsockopt() to pass iptable commands into umh via bpfilter.ko If admin does 'rmmod bpfilter' the __exit code bpfilter.ko will kill umh as well. Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller