From ba7a44da68adfa4f0d8285de4cdc16e3754929a8 Mon Sep 17 00:00:00 2001
From: Andrii Nakryiko <andrii@kernel.org>
Date: Thu, 25 May 2023 15:13:10 -0700
Subject: [PATCH] libbpf: Ensure libbpf always opens files with O_CLOEXEC

Make sure that libbpf code always gets FD with O_CLOEXEC flag set,
regardless if file is open through open() or fopen(). For the latter
this means to add "e" to mode string, which is supported since pretty
ancient glibc v2.7.

Also drop the outdated TODO comment in usdt.c, which was already completed.

Conflict: NA
Reference:https://github.com/libbpf/libbpf/commit/ba7a44da68adfa4f0d8285de4cdc16e3754929a8

Suggested-by: Lennart Poettering <lennart@poettering.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230525221311.2136408-1-andrii@kernel.org
---
 src/btf.c           | 2 +-
 src/libbpf.c        | 6 +++---
 src/libbpf_probes.c | 2 +-
 src/usdt.c          | 5 ++---
 4 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/src/btf.c b/src/btf.c
index 0a2c07924..8484b563b 100644
--- a/src/btf.c
+++ b/src/btf.c
@@ -1064,7 +1064,7 @@ static struct btf *btf_parse_raw(const char *path, struct btf *base_btf)
 	int err = 0;
 	long sz;
 
-	f = fopen(path, "rb");
+	f = fopen(path, "rbe");
 	if (!f) {
 		err = -errno;
 		goto err_out;
diff --git a/src/libbpf.c b/src/libbpf.c
index 1ceb3a97d..60ef4c5e3 100644
--- a/src/libbpf.c
+++ b/src/libbpf.c
@@ -4351,7 +4351,7 @@ static int bpf_get_map_info_from_fdinfo(int fd, struct bpf_map_info *info)
 	snprintf(file, sizeof(file), "/proc/%d/fdinfo/%d", getpid(), fd);
 	memset(info, 0, sizeof(*info));
 
-	fp = fopen(file, "r");
+	fp = fopen(file, "re");
 	if (!fp) {
 		err = -errno;
 		pr_warn("failed to open %s: %d. No procfs support?\n", file,
@@ -7455,7 +7455,7 @@ int libbpf_kallsyms_parse(kallsyms_cb_t cb, void *ctx)
 	int ret, err = 0;
 	FILE *f;
 
-	f = fopen("/proc/kallsyms", "r");
+	f = fopen("/proc/kallsyms", "re");
 	if (!f) {
 		err = -errno;
 		pr_warn("failed to open /proc/kallsyms: %d\n", err);
@@ -10075,7 +10075,7 @@ static int parse_uint_from_file(const char *file, const char *fmt)
 	int err, ret;
 	FILE *f;
 
-	f = fopen(file, "r");
+	f = fopen(file, "re");
 	if (!f) {
 		err = -errno;
 		pr_debug("failed to open '%s': %s\n", file,
diff --git a/src/libbpf_probes.c b/src/libbpf_probes.c
index 6065f408a..5f78a023b 100644
--- a/src/libbpf_probes.c
+++ b/src/libbpf_probes.c
@@ -38,7 +38,7 @@ static __u32 get_ubuntu_kernel_version(void)
 	if (faccessat(AT_FDCWD, ubuntu_kver_file, R_OK, AT_EACCESS) != 0)
 		return 0;
 
-	f = fopen(ubuntu_kver_file, "r");
+	f = fopen(ubuntu_kver_file, "re");
 	if (!f)
 		return 0;
 
diff --git a/src/usdt.c b/src/usdt.c
index 086eef355..f1a141555 100644
--- a/src/usdt.c
+++ b/src/usdt.c
@@ -466,7 +466,7 @@ static int parse_vma_segs(int pid, const char *lib_path, struct elf_seg **segs,
 
 proceed:
 	sprintf(line, "/proc/%d/maps", pid);
-	f = fopen(line, "r");
+	f = fopen(line, "re");
 	if (!f) {
 		err = -errno;
 		pr_warn("usdt: failed to open '%s' to get base addr of '%s': %d\n",
@@ -954,8 +954,7 @@ struct bpf_link *usdt_manager_attach_usdt(struct usdt_manager *man, const struct
 	spec_map_fd = bpf_map__fd(man->specs_map);
 	ip_map_fd = bpf_map__fd(man->ip_to_spec_id_map);
 
-	/* TODO: perform path resolution similar to uprobe's */
-	fd = open(path, O_RDONLY);
+	fd = open(path, O_RDONLY | O_CLOEXEC);
 	if (fd < 0) {
 		err = -errno;
 		pr_warn("usdt: failed to open ELF binary '%s': %d\n", path, err);
--
2.23.0