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selftests/bpf: add a selftest with __user tag

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Added a selftest with three__user usages: a __user pointer-type argument
in bpf_testmod, a __user pointer-type struct member in bpf_testmod,
and a __user pointer-type struct member in vmlinux. In all cases,
directly accessing the user memory will result verification failure.

  $ ./test_progs -v -n 22/3
  ...
  libbpf: prog 'test_user1': BPF program load failed: Permission denied
  libbpf: prog 'test_user1': -- BEGIN PROG LOAD LOG --
  R1 type=ctx expected=fp
  0: R1=ctx(id=0,off=0,imm=0) R10=fp0
  ; int BPF_PROG(test_user1, struct bpf_testmod_btf_type_tag_1 *arg)
  0: (79) r1 = *(u64 *)(r1 +0)
  func 'bpf_testmod_test_btf_type_tag_user_1' arg0 has btf_id 136561 type STRUCT 'bpf_testmod_btf_type_tag_1'
  1: R1_w=user_ptr_bpf_testmod_btf_type_tag_1(id=0,off=0,imm=0)
  ; g = arg->a;
  1: (61) r1 = *(u32 *)(r1 +0)
  R1 invalid mem access 'user_ptr_'
  ...
  #22/3 btf_tag/btf_type_tag_user_mod1:OK

  $ ./test_progs -v -n 22/4
  ...
  libbpf: prog 'test_user2': BPF program load failed: Permission denied
  libbpf: prog 'test_user2': -- BEGIN PROG LOAD LOG --
  R1 type=ctx expected=fp
  0: R1=ctx(id=0,off=0,imm=0) R10=fp0
  ; int BPF_PROG(test_user2, struct bpf_testmod_btf_type_tag_2 *arg)
  0: (79) r1 = *(u64 *)(r1 +0)
  func 'bpf_testmod_test_btf_type_tag_user_2' arg0 has btf_id 136563 type STRUCT 'bpf_testmod_btf_type_tag_2'
  1: R1_w=ptr_bpf_testmod_btf_type_tag_2(id=0,off=0,imm=0)
  ; g = arg->p->a;
  1: (79) r1 = *(u64 *)(r1 +0)          ; R1_w=user_ptr_bpf_testmod_btf_type_tag_1(id=0,off=0,imm=0)
  ; g = arg->p->a;
  2: (61) r1 = *(u32 *)(r1 +0)
  R1 invalid mem access 'user_ptr_'
  ...
  #22/4 btf_tag/btf_type_tag_user_mod2:OK

  $ ./test_progs -v -n 22/5
  ...
  libbpf: prog 'test_sys_getsockname': BPF program load failed: Permission denied
  libbpf: prog 'test_sys_getsockname': -- BEGIN PROG LOAD LOG --
  R1 type=ctx expected=fp
  0: R1=ctx(id=0,off=0,imm=0) R10=fp0
  ; int BPF_PROG(test_sys_getsockname, int fd, struct sockaddr *usockaddr,
  0: (79) r1 = *(u64 *)(r1 +8)
  func '__sys_getsockname' arg1 has btf_id 2319 type STRUCT 'sockaddr'
  1: R1_w=user_ptr_sockaddr(id=0,off=0,imm=0)
  ; g = usockaddr->sa_family;
  1: (69) r1 = *(u16 *)(r1 +0)
  R1 invalid mem access 'user_ptr_'
  ...
  #22/5 btf_tag/btf_type_tag_user_vmlinux:OK

Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20220127154616.659314-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Yonghong Song 2022-01-27 07:46:16 -08:00 committed by Alexei Starovoitov
parent 571d01a9d0
commit 696c390115
3 changed files with 151 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

18
tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
View file

@ -21,6 +21,24 @@ bpf_testmod_test_mod_kfunc(int i)
*(int *)this_cpu_ptr(&bpf_testmod_ksym_percpu) = i;
}
struct bpf_testmod_btf_type_tag_1 {
int a;
};
struct bpf_testmod_btf_type_tag_2 {
struct bpf_testmod_btf_type_tag_1 __user *p;
};
noinline int
bpf_testmod_test_btf_type_tag_user_1(struct bpf_testmod_btf_type_tag_1 __user *arg) {
return arg->a;
}
noinline int
bpf_testmod_test_btf_type_tag_user_2(struct bpf_testmod_btf_type_tag_2 *arg) {
return arg->p->a;
}
noinline int bpf_testmod_loop_test(int n)
{
int i, sum = 0;

93
tools/testing/selftests/bpf/prog_tests/btf_tag.c
View file

@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2021 Facebook */
#include <test_progs.h>
#include <bpf/btf.h>
#include "test_btf_decl_tag.skel.h"
/* struct btf_type_tag_test is referenced in btf_type_tag.skel.h */
@ -8,6 +9,7 @@ struct btf_type_tag_test {
int **p;
};
#include "btf_type_tag.skel.h"
#include "btf_type_tag_user.skel.h"
static void test_btf_decl_tag(void)
{
@ -41,10 +43,101 @@ static void test_btf_type_tag(void)
btf_type_tag__destroy(skel);
}
static void test_btf_type_tag_mod_user(bool load_test_user1)
{
const char *module_name = "bpf_testmod";
struct btf *vmlinux_btf, *module_btf;
struct btf_type_tag_user *skel;
__s32 type_id;
int err;
if (!env.has_testmod) {
test__skip();
return;
}
/* skip the test if the module does not have __user tags */
vmlinux_btf = btf__load_vmlinux_btf();
if (!ASSERT_OK_PTR(vmlinux_btf, "could not load vmlinux BTF"))
return;
module_btf = btf__load_module_btf(module_name, vmlinux_btf);
if (!ASSERT_OK_PTR(module_btf, "could not load module BTF"))
goto free_vmlinux_btf;
type_id = btf__find_by_name_kind(module_btf, "user", BTF_KIND_TYPE_TAG);
if (type_id <= 0) {
printf("%s:SKIP: btf_type_tag attribute not in %s", __func__, module_name);
test__skip();
goto free_module_btf;
}
skel = btf_type_tag_user__open();
if (!ASSERT_OK_PTR(skel, "btf_type_tag_user"))
goto free_module_btf;
bpf_program__set_autoload(skel->progs.test_sys_getsockname, false);
if (load_test_user1)
bpf_program__set_autoload(skel->progs.test_user2, false);
else
bpf_program__set_autoload(skel->progs.test_user1, false);
err = btf_type_tag_user__load(skel);
ASSERT_ERR(err, "btf_type_tag_user");
btf_type_tag_user__destroy(skel);
free_module_btf:
btf__free(module_btf);
free_vmlinux_btf:
btf__free(vmlinux_btf);
}
static void test_btf_type_tag_vmlinux_user(void)
{
struct btf_type_tag_user *skel;
struct btf *vmlinux_btf;
__s32 type_id;
int err;
/* skip the test if the vmlinux does not have __user tags */
vmlinux_btf = btf__load_vmlinux_btf();
if (!ASSERT_OK_PTR(vmlinux_btf, "could not load vmlinux BTF"))
return;
type_id = btf__find_by_name_kind(vmlinux_btf, "user", BTF_KIND_TYPE_TAG);
if (type_id <= 0) {
printf("%s:SKIP: btf_type_tag attribute not in vmlinux btf", __func__);
test__skip();
goto free_vmlinux_btf;
}
skel = btf_type_tag_user__open();
if (!ASSERT_OK_PTR(skel, "btf_type_tag_user"))
goto free_vmlinux_btf;
bpf_program__set_autoload(skel->progs.test_user2, false);
bpf_program__set_autoload(skel->progs.test_user1, false);
err = btf_type_tag_user__load(skel);
ASSERT_ERR(err, "btf_type_tag_user");
btf_type_tag_user__destroy(skel);
free_vmlinux_btf:
btf__free(vmlinux_btf);
}
void test_btf_tag(void)
{
if (test__start_subtest("btf_decl_tag"))
test_btf_decl_tag();
if (test__start_subtest("btf_type_tag"))
test_btf_type_tag();
if (test__start_subtest("btf_type_tag_user_mod1"))
test_btf_type_tag_mod_user(true);
if (test__start_subtest("btf_type_tag_user_mod2"))
test_btf_type_tag_mod_user(false);
if (test__start_subtest("btf_type_tag_sys_user_vmlinux"))
test_btf_type_tag_vmlinux_user();
}

40
tools/testing/selftests/bpf/progs/btf_type_tag_user.c Normal file
View file

@ -0,0 +1,40 @@
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2022 Facebook */
#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
struct bpf_testmod_btf_type_tag_1 {
int a;
};
struct bpf_testmod_btf_type_tag_2 {
struct bpf_testmod_btf_type_tag_1 *p;
};
int g;
SEC("fentry/bpf_testmod_test_btf_type_tag_user_1")
int BPF_PROG(test_user1, struct bpf_testmod_btf_type_tag_1 *arg)
{
g = arg->a;
return 0;
}
SEC("fentry/bpf_testmod_test_btf_type_tag_user_2")
int BPF_PROG(test_user2, struct bpf_testmod_btf_type_tag_2 *arg)
{
g = arg->p->a;
return 0;
}
/* int __sys_getsockname(int fd, struct sockaddr __user *usockaddr,
* int __user *usockaddr_len);
*/
SEC("fentry/__sys_getsockname")
int BPF_PROG(test_sys_getsockname, int fd, struct sockaddr *usockaddr,
int *usockaddr_len)
{
g = usockaddr->sa_family;
return 0;
}