From: Florent Revest <revest@chromium.org>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>, Yonghong Song <yhs@fb.com>,
KP Singh <kpsingh@kernel.org>,
Brendan Jackman <jackmanb@chromium.org>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH bpf-next 1/5] bpf: Add a ARG_PTR_TO_CONST_STR argument type
Date: Wed, 17 Mar 2021 00:58:30 +0100 [thread overview]
Message-ID: <CABRcYmJ3W88bTKwuO9Aav8A+TXmSE=SpxX++6OR77n=ya9hfgw@mail.gmail.com> (raw)
In-Reply-To: <CAEf4BzZ6Lfmn9pEJSLVhROjkPGJO_mT4nHot8AOjZ_9HTC1rEQ@mail.gmail.com>
On Tue, Mar 16, 2021 at 2:03 AM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
> On Wed, Mar 10, 2021 at 2:02 PM Florent Revest <revest@chromium.org> wrote:
> > + } else if (arg_type == ARG_PTR_TO_CONST_STR) {
> > + struct bpf_map *map = reg->map_ptr;
> > + int map_off, i;
> > + u64 map_addr;
> > + char *map_ptr;
> > +
> > + if (!map || !bpf_map_is_rdonly(map)) {
> > + verbose(env, "R%d does not point to a readonly map'\n", regno);
> > + return -EACCES;
> > + }
> > +
> > + if (!tnum_is_const(reg->var_off)) {
> > + verbose(env, "R%d is not a constant address'\n", regno);
> > + return -EACCES;
> > + }
> > +
> > + if (!map->ops->map_direct_value_addr) {
> > + verbose(env, "no direct value access support for this map type\n");
> > + return -EACCES;
> > + }
> > +
> > + err = check_helper_mem_access(env, regno,
> > + map->value_size - reg->off,
> > + false, meta);
>
> you expect reg to be PTR_TO_MAP_VALUE, so probably better to directly
> use check_map_access(). And double-check that register is of expected
> type. just the presence of ref->map_ptr might not be sufficient?
Sorry, just making sure I understand your comment correctly, are you
suggesting that we:
1- skip the check_map_access_type() currently done by
check_helper_mem_access()? or did you implicitly mean that we should
call it as well next to check_map_access() ?
2- enforce (reg->type == PTR_TO_MAP_VALUE) even if currently
guaranteed by compatible_reg_types, just to stay on the safe side ?
next prev parent reply other threads:[~2021-03-16 23:59 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-10 22:02 [PATCH bpf-next 0/5] Add a snprintf eBPF helper Florent Revest
2021-03-10 22:02 ` [PATCH bpf-next 1/5] bpf: Add a ARG_PTR_TO_CONST_STR argument type Florent Revest
2021-03-11 0:04 ` kernel test robot
2021-03-11 1:00 ` kernel test robot
2021-03-16 1:03 ` Andrii Nakryiko
2021-03-16 23:58 ` Florent Revest [this message]
2021-03-17 0:35 ` Andrii Nakryiko
2021-03-17 0:45 ` Florent Revest
2021-03-17 1:02 ` Andrii Nakryiko
2021-03-17 10:32 ` Florent Revest
2021-03-10 22:02 ` [PATCH bpf-next 2/5] bpf: Add a bpf_snprintf helper Florent Revest
2021-03-11 0:14 ` kernel test robot
2021-03-11 3:12 ` kernel test robot
2021-03-11 3:12 ` [RFC PATCH] bpf: check_bpf_snprintf_call() can be static kernel test robot
2021-03-16 1:25 ` [PATCH bpf-next 2/5] bpf: Add a bpf_snprintf helper Andrii Nakryiko
2021-03-16 13:18 ` Florent Revest
2021-03-23 3:21 ` Alexei Starovoitov
2021-03-23 14:04 ` Florent Revest
2021-03-10 22:02 ` [PATCH bpf-next 3/5] libbpf: Initialize the bpf_seq_printf parameters array field by field Florent Revest
2021-03-16 4:36 ` Andrii Nakryiko
2021-03-16 4:41 ` Andrii Nakryiko
2021-03-16 22:43 ` Florent Revest
2021-03-16 23:06 ` Andrii Nakryiko
2021-03-10 22:02 ` [PATCH bpf-next 4/5] libbpf: Introduce a BPF_SNPRINTF helper macro Florent Revest
2021-03-16 4:39 ` Andrii Nakryiko
2021-03-10 22:02 ` [PATCH bpf-next 5/5] selftests/bpf: Add a series of tests for bpf_snprintf Florent Revest
2021-03-16 4:49 ` Andrii Nakryiko
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