The classic converter generates conditional jumps with:
if (BPF_SRC(fp->code) == BPF_K && (int) fp->k < 0) {
...
} else {
insn->dst_reg = BPF_REG_A;
insn->src_reg = BPF_REG_X;
insn->imm = fp->k;
bpf_src = BPF_SRC(fp->code);
}
but here, we enforce that the src_reg == BPF_REG_0. We should also allow
BPF_REG_X since that's what the converter generates; this enables us to
load eBPF programs that were generated by the converter.
Signed-off-by: Tycho Andersen <[email protected]>
CC: Kees Cook <[email protected]>
CC: Will Drewry <[email protected]>
CC: Oleg Nesterov <[email protected]>
CC: Andy Lutomirski <[email protected]>
CC: Pavel Emelyanov <[email protected]>
CC: Serge E. Hallyn <[email protected]>
CC: Alexei Starovoitov <[email protected]>
CC: Daniel Borkmann <[email protected]>
---
kernel/bpf/verifier.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 039d866..2fff8cd 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1080,7 +1080,12 @@ static int check_cond_jmp_op(struct verifier_env *env,
if (err)
return err;
} else {
- if (insn->src_reg != BPF_REG_0) {
+ switch (insn->src_reg) {
+ case BPF_REG_0:
+ /* the classic converter generates BPF_JMP with src_reg of X */
+ case BPF_REG_X:
+ break;
+ default:
verbose("BPF_JMP uses reserved fields\n");
return -EINVAL;
}
--
2.1.4
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