lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Mon, 7 Feb 2022 10:33:43 -0800 From: Yonghong Song <yhs@...com> To: Hou Tao <hotforest@...il.com>, Daniel Borkmann <daniel@...earbox.net> CC: Alexei Starovoitov <ast@...nel.org>, Martin KaFai Lau <kafai@...com>, Andrii Nakryiko <andrii@...nel.org>, "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, John Fastabend <john.fastabend@...il.com>, <netdev@...r.kernel.org>, <bpf@...r.kernel.org>, <houtao1@...wei.com> Subject: Re: [PATCH bpf-next v4 2/2] selftests/bpf: check whether s32 is sufficient for kfunc offset On 2/5/22 8:31 PM, Hou Tao wrote: > In add_kfunc_call(), bpf_kfunc_desc->imm with type s32 is used to > represent the offset of called kfunc from __bpf_call_base, so > add a test to ensure that the offset will not be overflowed. > > Signed-off-by: Hou Tao <houtao1@...wei.com> > --- > .../selftests/bpf/prog_tests/ksyms_module.c | 42 +++++++++++++++++++ > 1 file changed, 42 insertions(+) > > diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms_module.c b/tools/testing/selftests/bpf/prog_tests/ksyms_module.c > index a1ebac70ec29..8055fbbf720b 100644 > --- a/tools/testing/selftests/bpf/prog_tests/ksyms_module.c > +++ b/tools/testing/selftests/bpf/prog_tests/ksyms_module.c > @@ -3,9 +3,49 @@ > > #include <test_progs.h> > #include <network_helpers.h> > +#include <trace_helpers.h> > #include "test_ksyms_module.lskel.h" > #include "test_ksyms_module.skel.h" > > +/* > + * Check whether or not s32 in bpf_kfunc_desc is sufficient > + * to represent the offset between bpf_testmod_test_mod_kfunc > + * and __bpf_call_base. > + */ > +static void test_ksyms_module_valid_offset(void) > +{ > + struct test_ksyms_module *skel; > + unsigned long long kfunc_addr; > + unsigned long long base_addr; > + long long actual_offset; > + int used_offset; > + int err; > + > + if (!env.has_testmod) { > + test__skip(); > + return; > + } > + > + /* Ensure kfunc call is supported */ > + skel = test_ksyms_module__open_and_load(); > + if (!ASSERT_OK_PTR(skel, "test_ksyms_module__open")) > + return; > + > + err = kallsyms_find("bpf_testmod_test_mod_kfunc", &kfunc_addr); > + if (!ASSERT_OK(err, "find kfunc addr")) > + goto cleanup; > + > + err = kallsyms_find("__bpf_call_base", &base_addr); > + if (!ASSERT_OK(err, "find base addr")) > + goto cleanup; > + > + used_offset = kfunc_addr - base_addr; > + actual_offset = kfunc_addr - base_addr; > + ASSERT_EQ((long long)used_offset, actual_offset, "kfunc offset overflowed"); I am a little bit confused about motivation here. Maybe I missed something. If we indeed have kfunc offset overflow, should kernel verifier just reject the program? Specially, we should make the above test_ksyms_module__open_and_load() fail? > +cleanup: > + test_ksyms_module__destroy(skel); > +} > + > static void test_ksyms_module_lskel(void) > { > struct test_ksyms_module_lskel *skel; > @@ -62,6 +102,8 @@ static void test_ksyms_module_libbpf(void) > > void test_ksyms_module(void) > { > + if (test__start_subtest("valid_offset")) > + test_ksyms_module_valid_offset(); > if (test__start_subtest("lskel")) > test_ksyms_module_lskel(); > if (test__start_subtest("libbpf"))
Powered by blists - more mailing lists