From: Kumar Kartikeya Dwivedi <memxor@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: bpf <bpf@vger.kernel.org>, "Alexei Starovoitov" <ast@kernel.org>,
"Andrii Nakryiko" <andrii@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Toke Høiland-Jørgensen" <toke@redhat.com>,
"Jesper Dangaard Brouer" <brouer@redhat.com>
Subject: Re: [PATCH bpf-next v3 09/13] bpf: Wire up freeing of referenced kptr
Date: Fri, 25 Mar 2022 20:37:51 +0530 [thread overview]
Message-ID: <20220325150751.6uybnqtdpf3umcm7@apollo> (raw)
In-Reply-To: <CAADnVQJd8E6T1GRMVS+XZxKDdnMjo-WQ-CdM7+x18VPj9ufpFQ@mail.gmail.com>
On Wed, Mar 23, 2022 at 02:40:17AM IST, Alexei Starovoitov wrote:
> On Sun, Mar 20, 2022 at 8:55 AM Kumar Kartikeya Dwivedi
> <memxor@gmail.com> wrote:
> >
> > + /* Find and stash the function pointer for the destruction function that
> > + * needs to be eventually invoked from the map free path.
> > + */
> > + if (info_arr[i].flags & BPF_MAP_VALUE_OFF_F_REF) {
> > + const struct btf_type *dtor_func, *dtor_func_proto;
> > + const struct btf_param *args;
> > + const char *dtor_func_name;
> > + unsigned long addr;
> > + s32 dtor_btf_id;
> > + u32 nr_args;
> > +
> > + /* This call also serves as a whitelist of allowed objects that
> > + * can be used as a referenced pointer and be stored in a map at
> > + * the same time.
> > + */
> > + dtor_btf_id = btf_find_dtor_kfunc(off_btf, id);
> > + if (dtor_btf_id < 0) {
> > + ret = dtor_btf_id;
> > + btf_put(off_btf);
> > + goto end;
> > + }
> > +
> > + dtor_func = btf_type_by_id(off_btf, dtor_btf_id);
> > + if (!dtor_func || !btf_type_is_func(dtor_func)) {
> > + ret = -EINVAL;
> > + btf_put(off_btf);
> > + goto end;
> > + }
> > +
> > + dtor_func_proto = btf_type_by_id(off_btf, dtor_func->type);
> > + if (!dtor_func_proto || !btf_type_is_func_proto(dtor_func_proto)) {
> > + ret = -EINVAL;
> > + btf_put(off_btf);
> > + goto end;
> > + }
> > +
> > + /* Make sure the prototype of the destructor kfunc is 'void func(type *)' */
> > + t = btf_type_by_id(off_btf, dtor_func_proto->type);
> > + if (!t || !btf_type_is_void(t)) {
> > + ret = -EINVAL;
> > + btf_put(off_btf);
> > + goto end;
> > + }
> > +
> > + nr_args = btf_type_vlen(dtor_func_proto);
> > + args = btf_params(dtor_func_proto);
> > +
> > + t = NULL;
> > + if (nr_args)
> > + t = btf_type_by_id(off_btf, args[0].type);
> > + /* Allow any pointer type, as width on targets Linux supports
> > + * will be same for all pointer types (i.e. sizeof(void *))
> > + */
> > + if (nr_args != 1 || !t || !btf_type_is_ptr(t)) {
> > + ret = -EINVAL;
> > + btf_put(off_btf);
> > + goto end;
> > + }
> > +
> > + if (btf_is_module(btf)) {
> > + mod = btf_try_get_module(off_btf);
> > + if (!mod) {
> > + ret = -ENXIO;
> > + btf_put(off_btf);
> > + goto end;
> > + }
> > + }
> > +
> > + dtor_func_name = __btf_name_by_offset(off_btf, dtor_func->name_off);
> > + addr = kallsyms_lookup_name(dtor_func_name);
> > + if (!addr) {
> > + ret = -EINVAL;
> > + module_put(mod);
> > + btf_put(off_btf);
> > + goto end;
> > + }
> > + tab->off[i].dtor = (void *)addr;
>
> Most of the above should probably be in register_btf_id_dtor_kfuncs().
> It's best to fail early.
> Here we'll just remember dtor function pointer to speed up release.
Ok, will move all of these checks to register_btf_id_dtor_kfuncs.
--
Kartikeya
next prev parent reply other threads:[~2022-03-25 15:09 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-20 15:54 [PATCH bpf-next v3 00/13] Introduce typed pointer support in BPF maps Kumar Kartikeya Dwivedi
2022-03-20 15:54 ` [PATCH bpf-next v3 01/13] bpf: Make btf_find_field more generic Kumar Kartikeya Dwivedi
2022-03-20 15:54 ` [PATCH bpf-next v3 02/13] bpf: Move check_ptr_off_reg before check_map_access Kumar Kartikeya Dwivedi
2022-03-20 15:55 ` [PATCH bpf-next v3 03/13] bpf: Allow storing unreferenced kptr in map Kumar Kartikeya Dwivedi
2022-03-21 23:39 ` Joanne Koong
2022-03-22 7:04 ` Kumar Kartikeya Dwivedi
2022-03-22 20:22 ` Andrii Nakryiko
2022-03-25 14:51 ` Kumar Kartikeya Dwivedi
2022-03-22 5:45 ` Andrii Nakryiko
2022-03-22 7:16 ` Kumar Kartikeya Dwivedi
2022-03-22 7:43 ` Kumar Kartikeya Dwivedi
2022-03-22 18:52 ` Andrii Nakryiko
2022-03-25 14:42 ` Kumar Kartikeya Dwivedi
2022-03-25 22:59 ` Andrii Nakryiko
2022-03-22 18:06 ` Martin KaFai Lau
2022-03-25 14:45 ` Kumar Kartikeya Dwivedi
2022-03-20 15:55 ` [PATCH bpf-next v3 04/13] bpf: Indicate argument that will be released in bpf_func_proto Kumar Kartikeya Dwivedi
2022-03-22 1:47 ` Joanne Koong
2022-03-22 7:34 ` Kumar Kartikeya Dwivedi
2022-03-20 15:55 ` [PATCH bpf-next v3 05/13] bpf: Allow storing referenced kptr in map Kumar Kartikeya Dwivedi
2022-03-22 20:59 ` Martin KaFai Lau
2022-03-25 14:57 ` Kumar Kartikeya Dwivedi
2022-03-25 23:39 ` Martin KaFai Lau
2022-03-26 1:01 ` Kumar Kartikeya Dwivedi
2022-03-20 15:55 ` [PATCH bpf-next v3 06/13] bpf: Prevent escaping of kptr loaded from maps Kumar Kartikeya Dwivedi
2022-03-22 5:58 ` Andrii Nakryiko
2022-03-22 7:18 ` Kumar Kartikeya Dwivedi
2022-03-20 15:55 ` [PATCH bpf-next v3 07/13] bpf: Adapt copy_map_value for multiple offset case Kumar Kartikeya Dwivedi
2022-03-22 20:38 ` Andrii Nakryiko
2022-03-25 15:06 ` Kumar Kartikeya Dwivedi
2022-03-20 15:55 ` [PATCH bpf-next v3 08/13] bpf: Populate pairs of btf_id and destructor kfunc in btf Kumar Kartikeya Dwivedi
2022-03-20 15:55 ` [PATCH bpf-next v3 09/13] bpf: Wire up freeing of referenced kptr Kumar Kartikeya Dwivedi
2022-03-22 20:51 ` Andrii Nakryiko
2022-03-25 14:50 ` Kumar Kartikeya Dwivedi
2022-03-22 21:10 ` Alexei Starovoitov
2022-03-25 15:07 ` Kumar Kartikeya Dwivedi [this message]
2022-03-20 15:55 ` [PATCH bpf-next v3 10/13] bpf: Teach verifier about kptr_get kfunc helpers Kumar Kartikeya Dwivedi
2022-03-20 15:55 ` [PATCH bpf-next v3 11/13] libbpf: Add kptr type tag macros to bpf_helpers.h Kumar Kartikeya Dwivedi
2022-03-20 15:55 ` [PATCH bpf-next v3 12/13] selftests/bpf: Add C tests for kptr Kumar Kartikeya Dwivedi
2022-03-22 21:00 ` Andrii Nakryiko
2022-03-25 14:52 ` Kumar Kartikeya Dwivedi
2022-03-24 9:10 ` Jiri Olsa
2022-03-25 14:52 ` Kumar Kartikeya Dwivedi
2022-03-20 15:55 ` [PATCH bpf-next v3 13/13] selftests/bpf: Add verifier " Kumar Kartikeya Dwivedi
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