[PATCH net-next 4/5] bpftool: implement cgdetach command

[Roman Gushchin]

Implement cgdetach command, which allows to detach the bpf
program from a cgroup. It takes program id and attach type
as arguments.

Example:
$ ./bpftool cgdetach /sys/fs/cgroup/user.slice/ device 1

Signed-off-by: Roman Gushchin <guro@xxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx>
Cc: Martin KaFai Lau <kafai@xxxxxx>
---
 tools/bpf/bpftool/main.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 49 insertions(+), 1 deletion(-)

diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
index 8eb3b9bf5bb2..77fcc1a0bd5d 100644
--- a/tools/bpf/bpftool/main.c
+++ b/tools/bpf/bpftool/main.c
@@ -81,12 +81,13 @@ static int do_help(int argc, char **argv)
 		"Usage: %s [OPTIONS] OBJECT { COMMAND | help }\n"
 		"       %s batch file FILE\n"
 		"       %s cgattach FILE CGROUP TYPE\n"
+		"       %s cgdetach CGROUP TYPE ID\n"
 		"       %s version\n"
 		"\n"
 		"       OBJECT := { prog | map }\n"
 		"       " HELP_SPEC_OPTIONS "\n"
 		"",
-		bin_name, bin_name, bin_name, bin_name);
+		bin_name, bin_name, bin_name, bin_name, bin_name);
 
 	return 0;
 }
@@ -166,6 +167,7 @@ void fprint_hex(FILE *f, void *arg, unsigned int n, const char *sep)
 
 static int do_batch(int argc, char **argv);
 static int do_cgattach(int argc, char **argv);
+static int do_cgdetach(int argc, char **argv);
 
 static const struct cmd cmds[] = {
 	{ "help",	do_help },
@@ -173,6 +175,7 @@ static const struct cmd cmds[] = {
 	{ "prog",	do_prog },
 	{ "map",	do_map },
 	{ "cgattach",	do_cgattach },
+	{ "cgdetach",	do_cgdetach },
 	{ "version",	do_version },
 	{ 0 }
 };
@@ -338,6 +341,51 @@ static int do_cgattach(int argc, char **argv)
 	return 0;
 }
 
+static int do_cgdetach(int argc, char **argv)
+{
+	int prog_fd, cgroup_fd;
+	enum bpf_attach_type attach_type;
+
+	if (argc < 3) {
+		p_err("too few parameters for cgdetach\n");
+		return -1;
+	} else if (argc > 3) {
+		p_err("too many parameters for cgdetach\n");
+		return -1;
+	}
+
+	cgroup_fd = open(argv[0], O_RDONLY);
+	if (cgroup_fd < 0) {
+		p_err("can't open cgroup %s\n", argv[1]);
+		return -1;
+	}
+
+	attach_type = parse_attach_type(argv[1]);
+	if (attach_type == __MAX_BPF_ATTACH_TYPE) {
+		close(cgroup_fd);
+		p_err("Invalid attach type");
+		return -1;
+	}
+
+	prog_fd = bpf_prog_get_fd_by_id(atoi(argv[2]));
+	if (prog_fd < 0) {
+		p_err("invalid program id\n");
+		return -1;
+	}
+
+	if (bpf_prog_detach2(prog_fd, cgroup_fd, attach_type)) {
+		close(prog_fd);
+		close(cgroup_fd);
+		p_err("Failed to attach program");
+		return -1;
+	}
+
+	close(prog_fd);
+	close(cgroup_fd);
+
+	return 0;
+}
+
 int main(int argc, char **argv)
 {
 	static const struct option options[] = {
-- 
2.14.3