On Thu, Nov 3, 2022 at 1:36 AM Yang Jihong <yangjihong1@xxxxxxxxxx> wrote: > > The error code -EACCES is returned when bpf prog is tested in 32-bit environment, > This is because bpf_object__relocate modifies the instruction to change memory > size to 4 bytes, as shown in the following messages: > > libbpf: prog 'kfunc_call_test1': relo #2: matching candidate #0 <byte_off> [18342] struct __sk_buff.sk (0:30:0 @ offset 168) > libbpf: prog 'kfunc_call_test1': relo #2: patched insn #1 (LDX/ST/STX) off 168 -> 168 > libbpf: prog 'kfunc_call_test1': relo #2: patched insn #1 (LDX/ST/STX) mem_sz 8 -> 4 > > As a result, the bpf_skb_is_valid_access check fails. For 32-bit architecture, > unnecessary checks need to be deleted. > > Signed-off-by: Yang Jihong <yangjihong1@xxxxxxxxxx> > --- > net/core/filter.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/net/core/filter.c b/net/core/filter.c > index bb0136e7a8e4..eab7ce89740c 100644 > --- a/net/core/filter.c > +++ b/net/core/filter.c > @@ -8269,8 +8269,6 @@ static bool bpf_skb_is_valid_access(int off, int size, enum bpf_access_type type > return false; > break; > case offsetof(struct __sk_buff, sk): > - if (type == BPF_WRITE || size != sizeof(__u64)) > - return false; this probably should be specific to host architecture bitness? I'd imagine that size = 4 should be invalid on 64-bit arches (reading half of the pointer is bad) either way, please make sure to add tests specifically for this case in test_verifier > info->reg_type = PTR_TO_SOCK_COMMON_OR_NULL; > break; > case offsetof(struct __sk_buff, tstamp_type): > -- > 2.30.GIT >
