kernel.git/arch/x86/net, branch linux-5.12.y

bpf, x86: Fix extable offset calculation

2021-07-14T15:00:06Z

[ Upstream commit 328aac5ecd119ede3633f7d17969b1ff34ccc784 ] Commit 4c5de127598e1 ("bpf: Emit explicit NULL pointer checks for PROBE_LDX instructions.") is emitting a couple of instructions before the actual load. Consider those additional instructions while calculating extable offset. Fixes: 4c5de127598e1 ("bpf: Emit explicit NULL pointer checks for PROBE_LDX instructions.") Signed-off-by: Ravi Bangoria Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20210622110026.1157847-1-ravi.bangoria@linux.ibm.com Signed-off-by: Sasha Levin

bpf, x86: Validate computation of branch displacements for x86-32

2021-04-08T14:24:53Z

The branch displacement logic in the BPF JIT compilers for x86 assumes that, for any generated branch instruction, the distance cannot increase between optimization passes. But this assumption can be violated due to how the distances are computed. Specifically, whenever a backward branch is processed in do_jit(), the distance is computed by subtracting the positions in the machine code from different optimization passes. This is because part of addrs[] is already updated for the current optimization pass, before the branch instruction is visited. And so the optimizer can expand blocks of machine code in some cases. This can confuse the optimizer logic, where it assumes that a fixed point has been reached for all machine code blocks once the total program size stops changing. And then the JIT compiler can output abnormal machine code containing incorrect branch displacements. To mitigate this issue, we assert that a fixed point is reached while populating the output image. This rejects any problematic programs. The issue affects both x86-32 and x86-64. We mitigate separately to ease backporting. Signed-off-by: Piotr Krysiuk Reviewed-by: Daniel Borkmann Signed-off-by: Daniel Borkmann

bpf, x86: Validate computation of branch displacements for x86-64

2021-04-08T14:24:36Z

bpf: Use NOP_ATOMIC5 instead of emit_nops(&prog, 5) for BPF_TRAMP_F_CALL_ORIG

2021-03-20T02:25:39Z

__bpf_arch_text_poke does rewrite only for atomic nop5, emit_nops(xxx, 5) emits non-atomic one which breaks fentry/fexit with k8 atomics: P6_NOP5 == P6_NOP5_ATOMIC (0f1f440000 == 0f1f440000) K8_NOP5 != K8_NOP5_ATOMIC (6666906690 != 6666666690) Can be reproduced by doing "ideal_nops = k8_nops" in "arch_init_ideal_nops() and running fexit_bpf2bpf selftest. Fixes: e21aa341785c ("bpf: Fix fexit trampoline.") Signed-off-by: Stanislav Fomichev Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20210320000001.915366-1-sdf@google.com

bpf: Fix fexit trampoline.

2021-03-17T23:22:51Z

The fexit/fmod_ret programs can be attached to kernel functions that can sleep. The synchronize_rcu_tasks() will not wait for such tasks to complete. In such case the trampoline image will be freed and when the task wakes up the return IP will point to freed memory causing the crash. Solve this by adding percpu_ref_get/put for the duration of trampoline and separate trampoline vs its image life times. The "half page" optimization has to be removed, since first_half->second_half->first_half transition cannot be guaranteed to complete in deterministic time. Every trampoline update becomes a new image. The image with fmod_ret or fexit progs will be freed via percpu_ref_kill and call_rcu_tasks. Together they will wait for the original function and trampoline asm to complete. The trampoline is patched from nop to jmp to skip fexit progs. They are freed independently from the trampoline. The image with fentry progs only will be freed via call_rcu_tasks_trace+call_rcu_tasks which will wait for both sleepable and non-sleepable progs to complete. Fixes: fec56f5890d9 ("bpf: Introduce BPF trampoline") Reported-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Paul E. McKenney # for RCU Link: https://lore.kernel.org/bpf/20210316210007.38949-1-alexei.starovoitov@gmail.com

bpf, x86: Use kvmalloc_array instead kmalloc_array in bpf_jit_comp

2021-03-09T23:10:23Z

x86 bpf_jit_comp.c used kmalloc_array to store jited addresses for each bpf insn. With a large bpf program, we have see the following allocation failures in our production server: page allocation failure: order:5, mode:0x40cc0(GFP_KERNEL|__GFP_COMP), nodemask=(null),cpuset=/,mems_allowed=0" Call Trace: dump_stack+0x50/0x70 warn_alloc.cold.120+0x72/0xd2 ? __alloc_pages_direct_compact+0x157/0x160 __alloc_pages_slowpath+0xcdb/0xd00 ? get_page_from_freelist+0xe44/0x1600 ? vunmap_page_range+0x1ba/0x340 __alloc_pages_nodemask+0x2c9/0x320 kmalloc_order+0x18/0x80 kmalloc_order_trace+0x1d/0xa0 bpf_int_jit_compile+0x1e2/0x484 ? kmalloc_order_trace+0x1d/0xa0 bpf_prog_select_runtime+0xc3/0x150 bpf_prog_load+0x480/0x720 ? __mod_memcg_lruvec_state+0x21/0x100 __do_sys_bpf+0xc31/0x2040 ? close_pdeo+0x86/0xe0 do_syscall_64+0x42/0x110 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f2f300f7fa9 Code: Bad RIP value. Dumped assembly: ffffffff810b6d70 : ; { ffffffff810b6d70: e8 eb a5 b4 00 callq 0xffffffff81c01360 <__fentry__> ffffffff810b6d75: 41 57 pushq %r15 ... ffffffff810b6f39: e9 72 fe ff ff jmp 0xffffffff810b6db0 ; addrs = kmalloc_array(prog->len + 1, sizeof(*addrs), GFP_KERNEL); ffffffff810b6f3e: 8b 45 0c movl 12(%rbp), %eax ; return __kmalloc(bytes, flags); ffffffff810b6f41: be c0 0c 00 00 movl $3264, %esi ; addrs = kmalloc_array(prog->len + 1, sizeof(*addrs), GFP_KERNEL); ffffffff810b6f46: 8d 78 01 leal 1(%rax), %edi ; if (unlikely(check_mul_overflow(n, size, &bytes))) ffffffff810b6f49: 48 c1 e7 02 shlq $2, %rdi ; return __kmalloc(bytes, flags); ffffffff810b6f4d: e8 8e 0c 1d 00 callq 0xffffffff81287be0 <__kmalloc> ; if (!addrs) { ffffffff810b6f52: 48 85 c0 testq %rax, %rax Change kmalloc_array() to kvmalloc_array() to avoid potential allocation error for big bpf programs. Signed-off-by: Yonghong Song Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20210309015647.3657852-1-yhs@fb.com

bpf, x86: Fix BPF_FETCH atomic and/or/xor with r0 as src

2021-02-22T17:03:11Z

This code generates a CMPXCHG loop in order to implement atomic_fetch bitwise operations. Because CMPXCHG is hard-coded to use rax (which holds the BPF r0 value), it saves the _real_ r0 value into the internal "ax" temporary register and restores it once the loop is complete. In the middle of the loop, the actual bitwise operation is performed using src_reg. The bug occurs when src_reg is r0: as described above, r0 has been clobbered and the real r0 value is in the ax register. Therefore, perform this operation on the ax register instead, when src_reg is r0. Fixes: 981f94c3e921 ("bpf: Add bitwise atomic instructions") Signed-off-by: Brendan Jackman Signed-off-by: Daniel Borkmann Acked-by: KP Singh Link: https://lore.kernel.org/bpf/20210216125307.1406237-1-jackmanb@google.com

bpf: Add per-program recursion prevention mechanism

2021-02-11T15:19:13Z

Since both sleepable and non-sleepable programs execute under migrate_disable add recursion prevention mechanism to both types of programs when they're executed via bpf trampoline. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20210210033634.62081-5-alexei.starovoitov@gmail.com

bpf: Compute program stats for sleepable programs

2021-02-11T15:19:06Z

Since sleepable programs don't migrate from the cpu the excution stats can be computed for them as well. Reuse the same infrastructure for both sleepable and non-sleepable programs. run_cnt -> the number of times the program was executed. run_time_ns -> the program execution time in nanoseconds including the off-cpu time when the program was sleeping. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Acked-by: KP Singh Link: https://lore.kernel.org/bpf/20210210033634.62081-4-alexei.starovoitov@gmail.com

bpf: Emit explicit NULL pointer checks for PROBE_LDX instructions.

2021-02-04T15:46:44Z

PTR_TO_BTF_ID registers contain either kernel pointer or NULL. Emit the NULL check explicitly by JIT instead of going into do_user_addr_fault() on NULL deference. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Song Liu Link: https://lore.kernel.org/bpf/20210202053837.95909-1-alexei.starovoitov@gmail.com