tools: bpftool: Allow all prog/map handles for pinning objects

Documentation and interactive help for bpftool have always explained
that the regular handles for programs (id|name|tag|pinned) and maps
(id|name|pinned) can be passed to the utility when attempting to pin
objects (bpftool prog pin PROG / bpftool map pin MAP).

THIS IS A LIE!! The tool actually accepts only ids, as the parsing is
done in do_pin_any() in common.c instead of reusing the parsing
functions that have long been generic for program and map handles.

Instead of fixing the doc, fix the code. It is trivial to reuse the
generic parsing, and to simplify do_pin_any() in the process.

Do not accept to pin multiple objects at the same time with
prog_parse_fds() or map_parse_fds() (this would require a more complex
syntax for passing multiple sysfs paths and validating that they
correspond to the number of e.g. programs we find for a given name or
tag).

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200312184608.12050-2-quentin@isovalent.com

tools/bpf/bpftool/common.c

@@ -211,39 +211,14 @@ int do_pin_fd(int fd, const char *name)
 	return err;
 }
 
-int do_pin_any(int argc, char **argv, int (*get_fd_by_id)(__u32))
+int do_pin_any(int argc, char **argv, int (*get_fd)(int *, char ***))
 {
-	unsigned int id;
-	char *endptr;
 	int err;
 	int fd;
 
-	if (argc < 3) {
-		p_err("too few arguments, id ID and FILE path is required");
-		return -1;
-	} else if (argc > 3) {
-		p_err("too many arguments");
-		return -1;
-	}
-
-	if (!is_prefix(*argv, "id")) {
-		p_err("expected 'id' got %s", *argv);
-		return -1;
-	}
-	NEXT_ARG();
-
-	id = strtoul(*argv, &endptr, 0);
-	if (*endptr) {
-		p_err("can't parse %s as ID", *argv);
-		return -1;
-	}
-	NEXT_ARG();
-
-	fd = get_fd_by_id(id);
-	if (fd < 0) {
-		p_err("can't open object by id (%u): %s", id, strerror(errno));
-		return -1;
-	}
+	fd = get_fd(&argc, &argv);
+	if (fd < 0)
+		return fd;
 
 	err = do_pin_fd(fd, *argv);
 

tools/bpf/bpftool/main.h

@@ -146,7 +146,7 @@ char *get_fdinfo(int fd, const char *key);
 int open_obj_pinned(char *path, bool quiet);
 int open_obj_pinned_any(char *path, enum bpf_obj_type exp_type);
 int mount_bpffs_for_pin(const char *name);
-int do_pin_any(int argc, char **argv, int (*get_fd_by_id)(__u32));
+int do_pin_any(int argc, char **argv, int (*get_fd_by_id)(int *, char ***));
 int do_pin_fd(int fd, const char *name);
 
 int do_prog(int argc, char **arg);

tools/bpf/bpftool/map.c

@@ -1384,7 +1384,7 @@ static int do_pin(int argc, char **argv)
 {
 	int err;
 
-	err = do_pin_any(argc, argv, bpf_map_get_fd_by_id);
+	err = do_pin_any(argc, argv, map_parse_fd);
 	if (!err && json_output)
 		jsonw_null(json_wtr);
 	return err;

tools/bpf/bpftool/prog.c

@@ -813,7 +813,7 @@ static int do_pin(int argc, char **argv)
 {
 	int err;
 
-	err = do_pin_any(argc, argv, bpf_prog_get_fd_by_id);
+	err = do_pin_any(argc, argv, prog_parse_fd);
 	if (!err && json_output)
 		jsonw_null(json_wtr);
 	return err;