linux/kernel/bpf/core.c, branch v5.19

bpf: Make sure mac_header was set before using it

2022-07-07T18:13:13Z

Classic BPF has a way to load bytes starting from the mac header. Some skbs do not have a mac header, and skb_mac_header() in this case is returning a pointer that 65535 bytes after skb->head. Existing range check in bpf_internal_load_pointer_neg_helper() was properly kicking and no illegal access was happening. New sanity check in skb_mac_header() is firing, so we need to avoid it. WARNING: CPU: 1 PID: 28990 at include/linux/skbuff.h:2785 skb_mac_header include/linux/skbuff.h:2785 [inline] WARNING: CPU: 1 PID: 28990 at include/linux/skbuff.h:2785 bpf_internal_load_pointer_neg_helper+0x1b1/0x1c0 kernel/bpf/core.c:74 Modules linked in: CPU: 1 PID: 28990 Comm: syz-executor.0 Not tainted 5.19.0-rc4-syzkaller-00865-g4874fb9484be #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022 RIP: 0010:skb_mac_header include/linux/skbuff.h:2785 [inline] RIP: 0010:bpf_internal_load_pointer_neg_helper+0x1b1/0x1c0 kernel/bpf/core.c:74 Code: ff ff 45 31 f6 e9 5a ff ff ff e8 aa 27 40 00 e9 3b ff ff ff e8 90 27 40 00 e9 df fe ff ff e8 86 27 40 00 eb 9e e8 2f 2c f3 ff <0f> 0b eb b1 e8 96 27 40 00 e9 79 fe ff ff 90 41 57 41 56 41 55 41 RSP: 0018:ffffc9000309f668 EFLAGS: 00010216 RAX: 0000000000000118 RBX: ffffffffffeff00c RCX: ffffc9000e417000 RDX: 0000000000040000 RSI: ffffffff81873f21 RDI: 0000000000000003 RBP: ffff8880842878c0 R08: 0000000000000003 R09: 000000000000ffff R10: 000000000000ffff R11: 0000000000000001 R12: 0000000000000004 R13: ffff88803ac56c00 R14: 000000000000ffff R15: dffffc0000000000 FS: 00007f5c88a16700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fdaa9f6c058 CR3: 000000003a82c000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ____bpf_skb_load_helper_32 net/core/filter.c:276 [inline] bpf_skb_load_helper_32+0x191/0x220 net/core/filter.c:264 Fixes: f9aefd6b2aa3 ("net: warn if mac header was not set") Reported-by: syzbot Signed-off-by: Eric Dumazet Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220707123900.945305-1-edumazet@google.com

bpf: Fix probe read error in ___bpf_prog_run()

2022-05-27T23:09:18Z

I think there is something wrong with BPF_PROBE_MEM in ___bpf_prog_run() in big-endian machine. Let's make a test and see what will happen if we want to load a 'u16' with BPF_PROBE_MEM. Let's make the src value '0x0001', the value of dest register will become 0x0001000000000000, as the value will be loaded to the first 2 byte of DST with following code: bpf_probe_read_kernel(&DST, SIZE, (const void *)(long) (SRC + insn->off)); Obviously, the value in DST is not correct. In fact, we can compare BPF_PROBE_MEM with LDX_MEM_H: DST = *(SIZE *)(unsigned long) (SRC + insn->off); If the memory load is done by LDX_MEM_H, the value in DST will be 0x1 now. And I think this error results in the test case 'test_bpf_sk_storage_map' failing: test_bpf_sk_storage_map:PASS:bpf_iter_bpf_sk_storage_map__open_and_load 0 nsec test_bpf_sk_storage_map:PASS:socket 0 nsec test_bpf_sk_storage_map:PASS:map_update 0 nsec test_bpf_sk_storage_map:PASS:socket 0 nsec test_bpf_sk_storage_map:PASS:map_update 0 nsec test_bpf_sk_storage_map:PASS:socket 0 nsec test_bpf_sk_storage_map:PASS:map_update 0 nsec test_bpf_sk_storage_map:PASS:attach_iter 0 nsec test_bpf_sk_storage_map:PASS:create_iter 0 nsec test_bpf_sk_storage_map:PASS:read 0 nsec test_bpf_sk_storage_map:FAIL:ipv6_sk_count got 0 expected 3 $10/26 bpf_iter/bpf_sk_storage_map:FAIL The code of the test case is simply, it will load sk->sk_family to the register with BPF_PROBE_MEM and check if it is AF_INET6. With this patch, now the test case 'bpf_iter' can pass: $10 bpf_iter:OK Fixes: 2a02759ef5f8 ("bpf: Add support for BTF pointers to interpreter") Signed-off-by: Menglong Dong Signed-off-by: Daniel Borkmann Reviewed-by: Jiang Biao Reviewed-by: Hao Peng Cc: Ilya Leoshkevich Link: https://lore.kernel.org/bpf/20220524021228.533216-1-imagedong@tencent.com

bpf: Introduce bpf_arch_text_invalidate for bpf_prog_pack

2022-05-23T21:08:11Z

Introduce bpf_arch_text_invalidate and use it to fill unused part of the bpf_prog_pack with illegal instructions when a BPF program is freed. Fixes: 57631054fae6 ("bpf: Introduce bpf_prog_pack allocator") Fixes: 33c9805860e5 ("bpf: Introduce bpf_jit_binary_pack_[alloc|finalize|free]") Reported-by: Linus Torvalds Signed-off-by: Song Liu Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220520235758.1858153-4-song@kernel.org

bpf: Fill new bpf_prog_pack with illegal instructions

2022-05-23T21:07:29Z

bpf_prog_pack enables sharing huge pages among multiple BPF programs. These pages are marked as executable before the JIT engine fill it with BPF programs. To make these pages safe, fill the hole bpf_prog_pack with illegal instructions before making it executable. Fixes: 57631054fae6 ("bpf: Introduce bpf_prog_pack allocator") Fixes: 33c9805860e5 ("bpf: Introduce bpf_jit_binary_pack_[alloc|finalize|free]") Reported-by: Linus Torvalds Signed-off-by: Song Liu Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220520235758.1858153-2-song@kernel.org

bpf: Fix combination of jit blinding and pointers to bpf subprogs.

2022-05-13T13:13:48Z

The combination of jit blinding and pointers to bpf subprogs causes: [ 36.989548] BUG: unable to handle page fault for address: 0000000100000001 [ 36.990342] #PF: supervisor instruction fetch in kernel mode [ 36.990968] #PF: error_code(0x0010) - not-present page [ 36.994859] RIP: 0010:0x100000001 [ 36.995209] Code: Unable to access opcode bytes at RIP 0xffffffd7. [ 37.004091] Call Trace: [ 37.004351] [ 37.004576] ? bpf_loop+0x4d/0x70 [ 37.004932] ? bpf_prog_3899083f75e4c5de_F+0xe3/0x13b The jit blinding logic didn't recognize that ld_imm64 with an address of bpf subprogram is a special instruction and proceeded to randomize it. By itself it wouldn't have been an issue, but jit_subprogs() logic relies on two step process to JIT all subprogs and then JIT them again when addresses of all subprogs are known. Blinding process in the first JIT phase caused second JIT to miss adjustment of special ld_imm64. Fix this issue by ignoring special ld_imm64 instructions that don't have user controlled constants and shouldn't be blinded. Fixes: 69c087ba6225 ("bpf: Add bpf_for_each_map_elem() helper") Reported-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/bpf/20220513011025.13344-1-alexei.starovoitov@gmail.com

bpf: add bpf_map_lookup_percpu_elem for percpu map

2022-05-12T01:16:54Z

Add new ebpf helpers bpf_map_lookup_percpu_elem. The implementation method is relatively simple, refer to the implementation method of map_lookup_elem of percpu map, increase the parameters of cpu, and obtain it according to the specified cpu. Signed-off-by: Feng Zhou Link: https://lore.kernel.org/r/20220511093854.411-2-zhoufeng.zf@bytedance.com Signed-off-by: Alexei Starovoitov

bpf: Fix bpf_prog_pack when PMU_SIZE is not defined

2022-03-21T20:53:45Z

PMD_SIZE is not available in some special config, e.g. ARCH=arm with CONFIG_MMU=n. Use bpf_prog_pack of PAGE_SIZE in these cases. Fixes: ef078600eec2 ("bpf: Select proper size for bpf_prog_pack") Reported-by: kernel test robot Signed-off-by: Song Liu Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20220321180009.1944482-3-song@kernel.org

bpf: Fix bpf_prog_pack for multi-node setup

2022-03-21T20:53:45Z

module_alloc requires num_online_nodes * PMD_SIZE to allocate huge pages. bpf_prog_pack uses pack of size num_online_nodes * PMD_SIZE. OTOH, module_alloc returns addresses that are PMD_SIZE aligned (instead of num_online_nodes * PMD_SIZE aligned). Therefore, PMD_MASK should be used to calculate pack_ptr in bpf_prog_pack_free(). Fixes: ef078600eec2 ("bpf: Select proper size for bpf_prog_pack") Reported-by: syzbot+c946805b5ce6ab87df0b@syzkaller.appspotmail.com Signed-off-by: Song Liu Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20220321180009.1944482-2-song@kernel.org

bpf: Select proper size for bpf_prog_pack

2022-03-21T02:07:14Z

Using HPAGE_PMD_SIZE as the size for bpf_prog_pack is not ideal in some cases. Specifically, for NUMA systems, __vmalloc_node_range requires PMD_SIZE * num_online_nodes() to allocate huge pages. Also, if the system does not support huge pages (i.e., with cmdline option nohugevmalloc), it is better to use PAGE_SIZE packs. Add logic to select proper size for bpf_prog_pack. This solution is not ideal, as it makes assumption about the behavior of module_alloc and __vmalloc_node_range. However, it appears to be the easiest solution as it doesn't require changes in module_alloc and vmalloc code. Fixes: 57631054fae6 ("bpf: Introduce bpf_prog_pack allocator") Signed-off-by: Song Liu Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20220311201135.3573610-1-song@kernel.org

bpf: Fix net.core.bpf_jit_harden race

2022-03-16T22:13:36Z

It is the bpf_jit_harden counterpart to commit 60b58afc96c9 ("bpf: fix net.core.bpf_jit_enable race"). bpf_jit_harden will be tested twice for each subprog if there are subprogs in bpf program and constant blinding may increase the length of program, so when running "./test_progs -t subprogs" and toggling bpf_jit_harden between 0 and 2, jit_subprogs may fail because constant blinding increases the length of subprog instructions during extra passs. So cache the value of bpf_jit_blinding_enabled() during program allocation, and use the cached value during constant blinding, subprog JITing and args tracking of tail call. Signed-off-by: Hou Tao Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20220309123321.2400262-4-houtao1@huawei.com