kernel.git/net/bpfilter, branch linux-4.18.y

net: bpfilter: use get_pid_task instead of pid_task

2018-11-04T13:51:55Z

[ Upstream commit 84258438e8ce12d6888b68a1238bba9cb25307e2 ] pid_task() dereferences rcu protected tasks array. But there is no rcu_read_lock() in shutdown_umh() routine so that rcu_read_lock() is needed. get_pid_task() is wrapper function of pid_task. it holds rcu_read_lock() then calls pid_task(). if task isn't NULL, it increases reference count of task. test commands: %modprobe bpfilter %modprobe -rv bpfilter splat looks like: [15102.030932] ============================= [15102.030957] WARNING: suspicious RCU usage [15102.030985] 4.19.0-rc7+ #21 Not tainted [15102.031010] ----------------------------- [15102.031038] kernel/pid.c:330 suspicious rcu_dereference_check() usage! [15102.031063] other info that might help us debug this: [15102.031332] rcu_scheduler_active = 2, debug_locks = 1 [15102.031363] 1 lock held by modprobe/1570: [15102.031389] #0: 00000000580ef2b0 (bpfilter_lock){+.+.}, at: stop_umh+0x13/0x52 [bpfilter] [15102.031552] stack backtrace: [15102.031583] CPU: 1 PID: 1570 Comm: modprobe Not tainted 4.19.0-rc7+ #21 [15102.031607] Hardware name: To be filled by O.E.M. To be filled by O.E.M./Aptio CRB, BIOS 5.6.5 07/08/2015 [15102.031628] Call Trace: [15102.031676] dump_stack+0xc9/0x16b [15102.031723] ? show_regs_print_info+0x5/0x5 [15102.031801] ? lockdep_rcu_suspicious+0x117/0x160 [15102.031855] pid_task+0x134/0x160 [15102.031900] ? find_vpid+0xf0/0xf0 [15102.032017] shutdown_umh.constprop.1+0x1e/0x53 [bpfilter] [15102.032055] stop_umh+0x46/0x52 [bpfilter] [15102.032092] __x64_sys_delete_module+0x47e/0x570 [ ... ] Fixes: d2ba09c17a06 ("net: add skeleton of bpfilter kernel module") Signed-off-by: Taehee Yoo Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

bpfilter: include bpfilter_umh in assembly instead of using objcopy

2018-06-28T12:39:16Z

What we want here is to embed a user-space program into the kernel. Instead of the complex ELF magic, let's simply wrap it in the assembly with the '.incbin' directive. Signed-off-by: Masahiro Yamada Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller

bpfilter: check compiler capability in Kconfig

2018-06-28T04:36:39Z

With the brand-new syntax extension of Kconfig, we can directly check the compiler capability in the configuration phase. If the cc-can-link.sh fails, the BPFILTER_UMH is automatically hidden by the dependency. I also deleted 'default n', which is no-op. Signed-off-by: Masahiro Yamada Acked-by: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller

bpfilter: fix user mode helper cross compilation

2018-06-21T00:19:19Z

Use $(OBJDUMP) instead of literal 'objdump' to avoid using host toolchain when cross compiling. Fixes: 421780fd4983 ("bpfilter: fix build error") Signed-off-by: Matteo Croce Reported-by: Stefano Brivio Signed-off-by: David S. Miller

bpfilter: ignore binary files

2018-06-20T00:07:46Z

net/bpfilter/bpfilter_umh is a binary file generated when bpfilter is enabled, add it to .gitignore to avoid committing it. Fixes: d2ba09c17a064 ("net: add skeleton of bpfilter kernel module") Signed-off-by: Matteo Croce Signed-off-by: David S. Miller

bpfilter: fix build error

2018-06-20T00:07:46Z

bpfilter Makefile assumes that the system locale is en_US, and the parsing of objdump output fails. Set LC_ALL=C and, while at it, rewrite the objdump parsing so it spawns only 2 processes instead of 7. Fixes: d2ba09c17a064 ("net: add skeleton of bpfilter kernel module") Signed-off-by: Matteo Croce Signed-off-by: David S. Miller

bpfilter: fix race in pipe access

2018-06-08T00:07:28Z

syzbot reported the following crash [ 338.293946] bpfilter: read fail -512 [ 338.304515] kasan: GPF could be caused by NULL-ptr deref or user memory access [ 338.311863] general protection fault: 0000 [#1] SMP KASAN [ 338.344360] RIP: 0010:__vfs_write+0x4a6/0x960 [ 338.426363] Call Trace: [ 338.456967] __kernel_write+0x10c/0x380 [ 338.460928] __bpfilter_process_sockopt+0x1d8/0x35b [ 338.487103] bpfilter_mbox_request+0x4d/0xb0 [ 338.491492] bpfilter_ip_get_sockopt+0x6b/0x90 This can happen when multiple cpus trying to talk to user mode process via bpfilter_mbox_request(). One cpu grabs the mutex while another goes to sleep on the same mutex. Then former cpu sees that umh pipe is down and shuts down the pipes. Later cpu finally acquires the mutex and crashes on freed pipe. Fix the race by using info.pid as an indicator that umh and pipes are healthy and check it after acquiring the mutex. Fixes: d2ba09c17a06 ("net: add skeleton of bpfilter kernel module") Reported-by: syzbot+7ade6c94abb2774c0fee@syzkaller.appspotmail.com Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller

bpfilter: fix OUTPUT_FORMAT

2018-06-07T20:56:48Z

CONFIG_OUTPUT_FORMAT is x86 only macro. Used objdump to extract elf file format. Fixes: d2ba09c17a06 ("net: add skeleton of bpfilter kernel module") Reported-by: David S. Miller Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller

bpfilter: switch to CC from HOSTCC

2018-06-05T14:21:18Z

check that CC can build executables and use that compiler instead of HOSTCC Suggested-by: Arnd Bergmann Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller

bpfilter: fix a build err

2018-05-29T19:20:21Z

gcc-7.3.0 report following err: HOSTCC net/bpfilter/main.o In file included from net/bpfilter/main.c:9:0: ./include/uapi/linux/bpf.h:12:10: fatal error: linux/bpf_common.h: No such file or directory #include remove it by adding a include path. Fixes: d2ba09c17a06 ("net: add skeleton of bpfilter kernel module") Signed-off-by: YueHaibing Signed-off-by: David S. Miller