selftests/bpf: add a selftest with __user tag

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>

diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
index bdbacf5adcd26c5fc590eb8a78f9db97bcf9fe82..595d32ab285ac60466718ffad022e3712a789c6e 100644 (file)
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
@@ -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;

diff --git a/tools/testing/selftests/bpf/prog_tests/btf_tag.c b/tools/testing/selftests/bpf/prog_tests/btf_tag.c
index c4cf27777ff755daf85e723b2854641783d63794..f7560b54a6bb53dd2df2c33d5878129361d23306 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/btf_tag.c
+++ b/tools/testing/selftests/bpf/prog_tests/btf_tag.c
@@ -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();
 }

diff --git a/tools/testing/selftests/bpf/progs/btf_type_tag_user.c b/tools/testing/selftests/bpf/progs/btf_type_tag_user.c
new file mode 100644 (file)
index 0000000..5523f77
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/btf_type_tag_user.c
@@ -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;
+}