1 files changed, 45 insertions, 5 deletions

diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 27e4e320e1a6..930cc9616527 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -15,6 +15,7 @@
 #include <linux/err.h>
 #include <fcntl.h>
 #include <unistd.h>
+#include <sys/syscall.h>
 #include <libelf.h>
 #include "relo_core.h"
 
@@ -360,15 +361,32 @@ enum kern_feature_id {
 	__FEAT_CNT,
 };
 
-int probe_memcg_account(void);
+enum kern_feature_result {
+	FEAT_UNKNOWN = 0,
+	FEAT_SUPPORTED = 1,
+	FEAT_MISSING = 2,
+};
+
+struct kern_feature_cache {
+	enum kern_feature_result res[__FEAT_CNT];
+	int token_fd;
+};
+
+bool feat_supported(struct kern_feature_cache *cache, enum kern_feature_id feat_id);
 bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id);
+
+int probe_kern_syscall_wrapper(int token_fd);
+int probe_memcg_account(int token_fd);
 int bump_rlimit_memlock(void);
 
 int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz);
 int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz);
 int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
-			 const char *str_sec, size_t str_len);
-int btf_load_into_kernel(struct btf *btf, char *log_buf, size_t log_sz, __u32 log_level);
+			 const char *str_sec, size_t str_len,
+			 int token_fd);
+int btf_load_into_kernel(struct btf *btf,
+			 char *log_buf, size_t log_sz, __u32 log_level,
+			 int token_fd);
 
 struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf);
 void btf_get_kernel_prefix_kind(enum bpf_attach_type attach_type,
@@ -532,6 +550,17 @@ static inline bool is_ldimm64_insn(struct bpf_insn *insn)
 	return insn->code == (BPF_LD | BPF_IMM | BPF_DW);
 }
 
+/* Unconditionally dup FD, ensuring it doesn't use [0, 2] range.
+ * Original FD is not closed or altered in any other way.
+ * Preserves original FD value, if it's invalid (negative).
+ */
+static inline int dup_good_fd(int fd)
+{
+	if (fd < 0)
+		return fd;
+	return fcntl(fd, F_DUPFD_CLOEXEC, 3);
+}
+
 /* if fd is stdin, stdout, or stderr, dup to a fd greater than 2
  * Takes ownership of the fd passed in, and closes it if calling
  * fcntl(fd, F_DUPFD_CLOEXEC, 3).
@@ -543,7 +572,7 @@ static inline int ensure_good_fd(int fd)
 	if (fd < 0)
 		return fd;
 	if (fd < 3) {
-		fd = fcntl(fd, F_DUPFD_CLOEXEC, 3);
+		fd = dup_good_fd(fd);
 		saved_errno = errno;
 		close(old_fd);
 		errno = saved_errno;
@@ -555,6 +584,15 @@ static inline int ensure_good_fd(int fd)
 	return fd;
 }
 
+static inline int sys_dup2(int oldfd, int newfd)
+{
+#ifdef __NR_dup2
+	return syscall(__NR_dup2, oldfd, newfd);
+#else
+	return syscall(__NR_dup3, oldfd, newfd, 0);
+#endif
+}
+
 /* Point *fixed_fd* to the same file that *tmp_fd* points to.
  * Regardless of success, *tmp_fd* is closed.
  * Whatever *fixed_fd* pointed to is closed silently.
@@ -563,7 +601,7 @@ static inline int reuse_fd(int fixed_fd, int tmp_fd)
 {
 	int err;
 
-	err = dup2(tmp_fd, fixed_fd);
+	err = sys_dup2(tmp_fd, fixed_fd);
 	err = err < 0 ? -errno : 0;
 	close(tmp_fd); /* clean up temporary FD */
 	return err;
@@ -613,4 +651,6 @@ int elf_resolve_syms_offsets(const char *binary_path, int cnt,
 int elf_resolve_pattern_offsets(const char *binary_path, const char *pattern,
 				 unsigned long **poffsets, size_t *pcnt);
 
+int probe_fd(int fd);
+
 #endif /* __LIBBPF_LIBBPF_INTERNAL_H */