From 6082b6c328b5486da2b356eae94b8b83c98b5565 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 7 Mar 2024 17:08:03 -0800 Subject: bpf: Recognize addr_space_cast instruction in the verifier. rY = addr_space_cast(rX, 0, 1) tells the verifier that rY->type = PTR_TO_ARENA. Any further operations on PTR_TO_ARENA register have to be in 32-bit domain. The verifier will mark load/store through PTR_TO_ARENA with PROBE_MEM32. JIT will generate them as kern_vm_start + 32bit_addr memory accesses. rY = addr_space_cast(rX, 1, 0) tells the verifier that rY->type = unknown scalar. If arena->map_flags has BPF_F_NO_USER_CONV set then convert cast_user to mov32 as well. Otherwise JIT will convert it to: rY = (u32)rX; if (rY) rY |= arena->user_vm_start & ~(u64)~0U; Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240308010812.89848-6-alexei.starovoitov@gmail.com --- kernel/bpf/syscall.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'kernel/bpf/syscall.c') diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 67923e41a07e..07f2a4db4511 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -4453,6 +4453,12 @@ static struct bpf_insn *bpf_insn_prepare_dump(const struct bpf_prog *prog, continue; } + if ((BPF_CLASS(code) == BPF_LDX || BPF_CLASS(code) == BPF_STX || + BPF_CLASS(code) == BPF_ST) && BPF_MODE(code) == BPF_PROBE_MEM32) { + insns[i].code = BPF_CLASS(code) | BPF_SIZE(code) | BPF_MEM; + continue; + } + if (code != (BPF_LD | BPF_IMM | BPF_DW)) continue; -- cgit v1.2.3