bpf: Undo internal BPF_PROBE_MEM in BPF insns dump

BPF_PROBE_MEM is kernel-internal implmementation details. When dumping BPF
instructions to user-space, it needs to be replaced back with BPF_MEM mode.

Fixes: 2a02759ef5f8 ("bpf: Add support for BTF pointers to interpreter")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200613002115.1632142-1-andriin@fb.com

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 4d530b1..e9a3ebc 100644 (file)
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3158,6 +3158,7 @@ static struct bpf_insn *bpf_insn_prepare_dump(const struct bpf_prog *prog)
        struct bpf_insn *insns;
        u32 off, type;
        u64 imm;
+       u8 code;
        int i;
 
        insns = kmemdup(prog->insnsi, bpf_prog_insn_size(prog),
@@ -3166,21 +3167,27 @@ static struct bpf_insn *bpf_insn_prepare_dump(const struct bpf_prog *prog)
                return insns;
 
        for (i = 0; i < prog->len; i++) {
-               if (insns[i].code == (BPF_JMP | BPF_TAIL_CALL)) {
+               code = insns[i].code;
+
+               if (code == (BPF_JMP | BPF_TAIL_CALL)) {
                        insns[i].code = BPF_JMP | BPF_CALL;
                        insns[i].imm = BPF_FUNC_tail_call;
                        /* fall-through */
                }
-               if (insns[i].code == (BPF_JMP | BPF_CALL) ||
-                   insns[i].code == (BPF_JMP | BPF_CALL_ARGS)) {
-                       if (insns[i].code == (BPF_JMP | BPF_CALL_ARGS))
+               if (code == (BPF_JMP | BPF_CALL) ||
+                   code == (BPF_JMP | BPF_CALL_ARGS)) {
+                       if (code == (BPF_JMP | BPF_CALL_ARGS))
                                insns[i].code = BPF_JMP | BPF_CALL;
                        if (!bpf_dump_raw_ok())
                                insns[i].imm = 0;
                        continue;
                }
+               if (BPF_CLASS(code) == BPF_LDX && BPF_MODE(code) == BPF_PROBE_MEM) {
+                       insns[i].code = BPF_LDX | BPF_SIZE(code) | BPF_MEM;
+                       continue;
+               }
 
-               if (insns[i].code != (BPF_LD | BPF_IMM | BPF_DW))
+               if (code != (BPF_LD | BPF_IMM | BPF_DW))
                        continue;
 
                imm = ((u64)insns[i + 1].imm << 32) | (u32)insns[i].imm;