Commit a8a71796 authored by Jiri Olsa's avatar Jiri Olsa Committed by Alexei Starovoitov
Browse files

selftests/bpf: Fix stat probe in d_path test 



Some kernels builds might inline vfs_getattr call within fstat
syscall code path, so fentry/vfs_getattr trampoline is not called.

Add security_inode_getattr to allowlist and switch the d_path test stat
trampoline to security_inode_getattr.

Keeping dentry_open and filp_close, because they are in their own
files, so unlikely to be inlined, but in case they are, adding
security_file_open.

Adding flags that indicate trampolines were called and failing
the test if any of them got missed, so it's easier to identify
the issue next time.

Fixes: e4d1af4b ("selftests/bpf: Add test for d_path helper")
Suggested-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarJiri Olsa <jolsa@redhat.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200918112338.2618444-1-jolsa@kernel.org
parent c69d2ddb

kernel/trace/bpf_trace.c

+8 −0
Original line number Diff line number Diff line
@@ -1114,6 +1114,14 @@ BPF_CALL_3(bpf_d_path, struct path *, path, char *, buf, u32, sz) 
}



BTF_SET_START(btf_allowlist_d_path)

#ifdef CONFIG_SECURITY

BTF_ID(func, security_file_permission)

BTF_ID(func, security_inode_getattr)

BTF_ID(func, security_file_open)

#endif

#ifdef CONFIG_SECURITY_PATH

BTF_ID(func, security_path_truncate)

#endif

BTF_ID(func, vfs_truncate)

BTF_ID(func, vfs_fallocate)

BTF_ID(func, dentry_open)

tools/testing/selftests/bpf/prog_tests/d_path.c

+10 −0
Original line number Diff line number Diff line
@@ -120,6 +120,16 @@ void test_d_path(void) 
	if (err < 0)

		goto cleanup;



	if (CHECK(!bss->called_stat,

		  "stat",

		  "trampoline for security_inode_getattr was not called\n"))

		goto cleanup;



	if (CHECK(!bss->called_close,

		  "close",

		  "trampoline for filp_close was not called\n"))

		goto cleanup;



	for (int i = 0; i < MAX_FILES; i++) {

		CHECK(strncmp(src.paths[i], bss->paths_stat[i], MAX_PATH_LEN),

		      "check",

tools/testing/selftests/bpf/progs/test_d_path.c

+8 −1
Original line number Diff line number Diff line
@@ -15,7 +15,10 @@ char paths_close[MAX_FILES][MAX_PATH_LEN] = {}; 
int rets_stat[MAX_FILES] = {};

int rets_close[MAX_FILES] = {};



SEC("fentry/vfs_getattr")

int called_stat = 0;

int called_close = 0;



SEC("fentry/security_inode_getattr")

int BPF_PROG(prog_stat, struct path *path, struct kstat *stat,

	     __u32 request_mask, unsigned int query_flags)

{
@@ -23,6 +26,8 @@ int BPF_PROG(prog_stat, struct path *path, struct kstat *stat, 
	__u32 cnt = cnt_stat;

	int ret;



	called_stat = 1;



	if (pid != my_pid)

		return 0;
@@ -42,6 +47,8 @@ int BPF_PROG(prog_close, struct file *file, void *id) 
	__u32 cnt = cnt_close;

	int ret;



	called_close = 1;



	if (pid != my_pid)

		return 0;

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