| Message ID | 20200819011244.2027725-1-udippant@fb.com |
|---|---|
| State | New |
| Headers | show |
| Series | [bpf] bpf: verifier: check for packet data access based on target prog | expand |
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index ef938f17b944..4d7604430994 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2629,7 +2629,11 @@ static bool may_access_direct_pkt_data(struct bpf_verifier_env *env, const struct bpf_call_arg_meta *meta, enum bpf_access_type t) { - switch (env->prog->type) { + struct bpf_prog *prog = env->prog; + enum bpf_prog_type prog_type = prog->aux->linked_prog ? + prog->aux->linked_prog->type : prog->type; + + switch (prog_type) { /* Program types only with direct read access go here! */ case BPF_PROG_TYPE_LWT_IN: case BPF_PROG_TYPE_LWT_OUT:
While using dynamic program extension (of type BPF_PROG_TYPE_EXT), we need to check the program type of the target program to grant the read / write access to the packet data. The BPF_PROG_TYPE_EXT type can be used to extend types such as XDP, SKB and others. Since the BPF_PROG_TYPE_EXT program type on itself is just a placeholder for those, we need this extended check for those target programs to actually work while using this option. Tested this with a freplace xdp program. Without this patch, the verifier fails with error 'cannot write into packet'. Signed-off-by: Udip Pant <udippant@fb.com> --- kernel/bpf/verifier.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)