selftests/bpf: Ensure core_reloc_kernel is reading test_progs's data only

test_core_reloc_kernel.c selftest is the only CO-RE test that reads and
returns for validation calling thread's information (pid, tgid, comm). Thus it
has to make sure that only test_prog's invocations are honored.

Fixes: df36e621418b ("selftests/bpf: add CO-RE relocs testing setup")
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20191121175900.3486133-1-andriin@fb.com

diff --git a/tools/testing/selftests/bpf/prog_tests/core_reloc.c b/tools/testing/selftests/bpf/prog_tests/core_reloc.c
index ec9e2fd..05fe852 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/core_reloc.c
+++ b/tools/testing/selftests/bpf/prog_tests/core_reloc.c
@@ -2,6 +2,7 @@
 #include <test_progs.h>
 #include "progs/core_reloc_types.h"
 #include <sys/mman.h>
+#include <sys/syscall.h>
 
 #define STRUCT_TO_CHAR_PTR(struct_name) (const char *)&(struct struct_name)
 
@@ -452,6 +453,7 @@ static struct core_reloc_test_case test_cases[] = {
 struct data {
        char in[256];
        char out[256];
+       uint64_t my_pid_tgid;
 };
 
 static size_t roundup_page(size_t sz)
@@ -471,9 +473,12 @@ void test_core_reloc(void)
        struct bpf_map *data_map;
        struct bpf_program *prog;
        struct bpf_object *obj;
+       uint64_t my_pid_tgid;
        struct data *data;
        void *mmap_data = NULL;
 
+       my_pid_tgid = getpid() | ((uint64_t)syscall(SYS_gettid) << 32);
+
        for (i = 0; i < ARRAY_SIZE(test_cases); i++) {
                test_case = &test_cases[i];
                if (!test__start_subtest(test_case->case_name))
@@ -517,11 +522,6 @@ void test_core_reloc(void)
                                goto cleanup;
                }
 
-               link = bpf_program__attach_raw_tracepoint(prog, tp_name);
-               if (CHECK(IS_ERR(link), "attach_raw_tp", "err %ld\n",
-                         PTR_ERR(link)))
-                       goto cleanup;
-
                data_map = bpf_object__find_map_by_name(obj, "test_cor.bss");
                if (CHECK(!data_map, "find_data_map", "data map not found\n"))
                        goto cleanup;
@@ -537,6 +537,12 @@ void test_core_reloc(void)
 
                memset(mmap_data, 0, sizeof(*data));
                memcpy(data->in, test_case->input, test_case->input_len);
+               data->my_pid_tgid = my_pid_tgid;
+
+               link = bpf_program__attach_raw_tracepoint(prog, tp_name);
+               if (CHECK(IS_ERR(link), "attach_raw_tp", "err %ld\n",
+                         PTR_ERR(link)))
+                       goto cleanup;
 
                /* trigger test run */
                usleep(1);

diff --git a/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c b/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
index 5d499eb..270de44 100644 (file)
--- a/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
+++ b/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
@@ -11,6 +11,7 @@ char _license[] SEC("license") = "GPL";
 struct {
        char in[256];
        char out[256];
+       uint64_t my_pid_tgid;
 } data = {};
 
 struct core_reloc_kernel_output {
@@ -38,6 +39,9 @@ int test_core_kernel(void *ctx)
        uint32_t real_tgid = (uint32_t)pid_tgid;
        int pid, tgid;
 
+       if (data.my_pid_tgid != pid_tgid)
+               return 0;
+
        if (CORE_READ(&pid, &task->pid) ||
            CORE_READ(&tgid, &task->tgid))
                return 1;