[bpf-next v2 1/2] libbpf: Add pathname_concat() helper

[bpf-next v2 1/2] libbpf: Add pathname_concat() helper

[Wang Yufen]

Move snprintf and len check to common helper pathname_concat() to make the
code simpler.

Signed-off-by: Wang Yufen <wangyufen@huawei.com>
---
 tools/lib/bpf/libbpf.c | 76 +++++++++++++++++++-------------------------------
 1 file changed, 29 insertions(+), 47 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 3ad1392..7ab977c 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2096,19 +2096,30 @@ static bool get_map_field_int(const char *map_name, const struct btf *btf,
 	return true;
 }
 
+static int pathname_concat(const char *path, const char *name, char *buf)
+{
+	int len;
+
+	len = snprintf(buf, PATH_MAX, "%s/%s", path, name);
+	if (len < 0)
+		return -EINVAL;
+	if (len >= PATH_MAX)
+		return -ENAMETOOLONG;
+
+	return 0;
+}
+
 static int build_map_pin_path(struct bpf_map *map, const char *path)
 {
 	char buf[PATH_MAX];
-	int len;
+	int err;
 
 	if (!path)
 		path = "/sys/fs/bpf";
 
-	len = snprintf(buf, PATH_MAX, "%s/%s", path, bpf_map__name(map));
-	if (len < 0)
-		return -EINVAL;
-	else if (len >= PATH_MAX)
-		return -ENAMETOOLONG;
+	err = pathname_concat(path, bpf_map__name(map), buf);
+	if (err)
+		return err;
 
 	return bpf_map__set_pin_path(map, buf);
 }
@@ -7961,17 +7972,9 @@ int bpf_object__pin_maps(struct bpf_object *obj, const char *path)
 			continue;
 
 		if (path) {
-			int len;
-
-			len = snprintf(buf, PATH_MAX, "%s/%s", path,
-				       bpf_map__name(map));
-			if (len < 0) {
-				err = -EINVAL;
-				goto err_unpin_maps;
-			} else if (len >= PATH_MAX) {
-				err = -ENAMETOOLONG;
+			err = pathname_concat(path, bpf_map__name(map), buf);
+			if (err)
 				goto err_unpin_maps;
-			}
 			sanitize_pin_path(buf);
 			pin_path = buf;
 		} else if (!map->pin_path) {
@@ -8009,14 +8012,9 @@ int bpf_object__unpin_maps(struct bpf_object *obj, const char *path)
 		char buf[PATH_MAX];
 
 		if (path) {
-			int len;
-
-			len = snprintf(buf, PATH_MAX, "%s/%s", path,
-				       bpf_map__name(map));
-			if (len < 0)
-				return libbpf_err(-EINVAL);
-			else if (len >= PATH_MAX)
-				return libbpf_err(-ENAMETOOLONG);
+			err = pathname_concat(path, bpf_map__name(map), buf);
+			if (err)
+				return err;
 			sanitize_pin_path(buf);
 			pin_path = buf;
 		} else if (!map->pin_path) {
@@ -8034,6 +8032,7 @@ int bpf_object__unpin_maps(struct bpf_object *obj, const char *path)
 int bpf_object__pin_programs(struct bpf_object *obj, const char *path)
 {
 	struct bpf_program *prog;
+	char buf[PATH_MAX];
 	int err;
 
 	if (!obj)
@@ -8045,17 +8044,9 @@ int bpf_object__pin_programs(struct bpf_object *obj, const char *path)
 	}
 
 	bpf_object__for_each_program(prog, obj) {
-		char buf[PATH_MAX];
-		int len;
-
-		len = snprintf(buf, PATH_MAX, "%s/%s", path, prog->name);
-		if (len < 0) {
-			err = -EINVAL;
-			goto err_unpin_programs;
-		} else if (len >= PATH_MAX) {
-			err = -ENAMETOOLONG;
+		err = pathname_concat(path, prog->name, buf);
+		if (err)
 			goto err_unpin_programs;
-		}
 
 		err = bpf_program__pin(prog, buf);
 		if (err)
@@ -8066,13 +8057,7 @@ int bpf_object__pin_programs(struct bpf_object *obj, const char *path)
 
 err_unpin_programs:
 	while ((prog = bpf_object__prev_program(obj, prog))) {
-		char buf[PATH_MAX];
-		int len;
-
-		len = snprintf(buf, PATH_MAX, "%s/%s", path, prog->name);
-		if (len < 0)
-			continue;
-		else if (len >= PATH_MAX)
+		if (pathname_concat(path, prog->name, buf))
 			continue;
 
 		bpf_program__unpin(prog, buf);
@@ -8091,13 +8076,10 @@ int bpf_object__unpin_programs(struct bpf_object *obj, const char *path)
 
 	bpf_object__for_each_program(prog, obj) {
 		char buf[PATH_MAX];
-		int len;
 
-		len = snprintf(buf, PATH_MAX, "%s/%s", path, prog->name);
-		if (len < 0)
-			return libbpf_err(-EINVAL);
-		else if (len >= PATH_MAX)
-			return libbpf_err(-ENAMETOOLONG);
+		err = pathname_concat(path, prog->name, buf);
+		if (err)
+			return libbpf_err(err);
 
 		err = bpf_program__unpin(prog, buf);
 		if (err)
-- 
1.8.3.1

[bpf-next v2 2/2] selftests/bpf: Add testcases for pinning to errpath

[Wang Yufen]

Add testcases for map and prog pin to errpath.

Signed-off-by: Wang Yufen <wangyufen@huawei.com>
---
 tools/testing/selftests/bpf/prog_tests/pinning.c   | 67 ++++++++++++++++++++++
 .../selftests/bpf/progs/test_pinning_path.c        | 19 ++++++
 2 files changed, 86 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/test_pinning_path.c

diff --git a/tools/testing/selftests/bpf/prog_tests/pinning.c b/tools/testing/selftests/bpf/prog_tests/pinning.c
index d95cee5..ab7780f 100644
--- a/tools/testing/selftests/bpf/prog_tests/pinning.c
+++ b/tools/testing/selftests/bpf/prog_tests/pinning.c
@@ -24,6 +24,61 @@ __u32 get_map_id(struct bpf_object *obj, const char *name)
 	return map_info.id;
 }
 
+static void test_pin_path(void)
+{
+	const char *progfile = "./test_pinning_path.bpf.o";
+	const char *progpinpath = "/sys/fs/bpf/test_pinpath";
+	char errpath[PATH_MAX + 1];
+	char command[64];
+	int prog_fd, err;
+	struct bpf_object *obj;
+	__u32 duration = 0;
+
+	/* Use libbpf 1.0 API mode */
+	libbpf_set_strict_mode(LIBBPF_STRICT_ALL);
+
+	err = bpf_prog_test_load(progfile, BPF_PROG_TYPE_SOCK_OPS, &obj,
+				 &prog_fd);
+	CHECK(err, "bpf_prog_test_load", "err %d errno %d\n", err, errno);
+
+	memset(&errpath, 't', PATH_MAX);
+	err = bpf_object__pin_maps(obj, errpath);
+	if (CHECK(err != -ENAMETOOLONG, "pin maps errpath", "err %d errno %d\n", err, errno))
+		goto out;
+
+	err = bpf_object__pin_maps(obj, progpinpath);
+	if (CHECK(err, "pin maps", "err %d errno %d\n", err, errno))
+		goto out;
+
+	err = bpf_object__pin_programs(obj, errpath);
+	if (CHECK(err != -ENAMETOOLONG, "pin progs errpath", "err %d errno %d\n", err, errno))
+		goto out;
+
+	err = bpf_object__pin_programs(obj, progpinpath);
+	if (CHECK(err, "pin prog", "err %d errno %d\n", err, errno))
+		goto out;
+
+	err = bpf_object__unpin_programs(obj, errpath);
+	if (CHECK(err != -ENAMETOOLONG, "pin progs errpath", "err %d errno %d\n", err, errno))
+		goto out;
+
+	err = bpf_object__unpin_programs(obj, progpinpath);
+	if (CHECK(err, "pin prog", "err %d errno %d\n", err, errno))
+		goto out;
+
+	err = bpf_object__unpin_maps(obj, errpath);
+	if (CHECK(err != -ENAMETOOLONG, "pin maps errpath", "err %d errno %d\n", err, errno))
+		goto out;
+
+	err = bpf_object__unpin_maps(obj, progpinpath);
+	if (CHECK(err, "pin maps", "err %d errno %d\n", err, errno))
+		goto out;
+out:
+	bpf_object__close(obj);
+	sprintf(command, "rm -r %s", progpinpath);
+	system(command);
+}
+
 void test_pinning(void)
 {
 	const char *file_invalid = "./test_pinning_invalid.bpf.o";
@@ -32,6 +87,7 @@ void test_pinning(void)
 	const char *nopinpath2 = "/sys/fs/bpf/nopinmap2";
 	const char *custpath = "/sys/fs/bpf/custom";
 	const char *pinpath = "/sys/fs/bpf/pinmap";
+	char errpath[PATH_MAX + 1];
 	const char *file = "./test_pinning.bpf.o";
 	__u32 map_id, map_id2, duration = 0;
 	struct stat statbuf = {};
@@ -206,7 +262,17 @@ void test_pinning(void)
 
 	bpf_object__close(obj);
 
+	/* test auto-pinning at err path with open opt */
+	memset(&errpath, 't', PATH_MAX);
+	opts.pin_root_path = errpath;
+	obj = bpf_object__open_file(file, &opts);
+	if (CHECK_FAIL(libbpf_get_error(obj) != -ENAMETOOLONG)) {
+		obj = NULL;
+		goto out;
+	}
+
 	/* test auto-pinning at custom path with open opt */
+	opts.pin_root_path = custpath;
 	obj = bpf_object__open_file(file, &opts);
 	if (CHECK_FAIL(libbpf_get_error(obj))) {
 		obj = NULL;
@@ -277,4 +343,5 @@ void test_pinning(void)
 	rmdir(custpath);
 	if (obj)
 		bpf_object__close(obj);
+	test_pin_path();
 }
diff --git a/tools/testing/selftests/bpf/progs/test_pinning_path.c b/tools/testing/selftests/bpf/progs/test_pinning_path.c
new file mode 100644
index 0000000..b4e2099
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_pinning_path.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+
+struct {
+	__uint(type, BPF_MAP_TYPE_SOCKHASH);
+	__uint(max_entries, 64);
+	__type(key, __u32);
+	__type(value, __u64);
+} sock_ops_map SEC(".maps");
+
+SEC("sockops")
+int bpf_sockmap(struct bpf_sock_ops *skops)
+{
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
-- 
1.8.3.1

Re: [bpf-next v2 1/2] libbpf: Add pathname_concat() helper

[Daniel Borkmann]

On 9/16/22 9:36 AM, Wang Yufen wrote:
> Move snprintf and len check to common helper pathname_concat() to make the
> code simpler.
> 
> Signed-off-by: Wang Yufen <wangyufen@huawei.com>
> ---
>   tools/lib/bpf/libbpf.c | 76 +++++++++++++++++++-------------------------------
>   1 file changed, 29 insertions(+), 47 deletions(-)
> 
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 3ad1392..7ab977c 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -2096,19 +2096,30 @@ static bool get_map_field_int(const char *map_name, const struct btf *btf,
>   	return true;
>   }
>   
> +static int pathname_concat(const char *path, const char *name, char *buf)
> +{
> +	int len;
> +
> +	len = snprintf(buf, PATH_MAX, "%s/%s", path, name);
> +	if (len < 0)
> +		return -EINVAL;
> +	if (len >= PATH_MAX)
> +		return -ENAMETOOLONG;
> +
> +	return 0;
> +}
> +
>   static int build_map_pin_path(struct bpf_map *map, const char *path)
>   {
>   	char buf[PATH_MAX];
> -	int len;
> +	int err;
>   
>   	if (!path)
>   		path = "/sys/fs/bpf";
>   
> -	len = snprintf(buf, PATH_MAX, "%s/%s", path, bpf_map__name(map));
> -	if (len < 0)
> -		return -EINVAL;
> -	else if (len >= PATH_MAX)
> -		return -ENAMETOOLONG;
> +	err = pathname_concat(path, bpf_map__name(map), buf);

Small nit, but would be good to not make the assumption that buf is always
PATH_MAX so lets add size_t len to pathname_concat().

> +	if (err)
> +		return err;
>   
>   	return bpf_map__set_pin_path(map, buf);
>   }