Thanks a lot for this!
2025-07-21 01:33 UTC+0800 ~ Tao Chen <chen.dylane@xxxxxxxxx>
> Add `bpftool token show` command to get token info
> from bpf fs in /proc/mounts.
>
> Example plain output for `token show`:
> token_info:
> /sys/fs/bpf/token
>
> allowed_cmds:
> map_create prog_load
>
> allowed_maps:
>
> allowed_progs:
> kprobe
>
> allowed_attachs:
> xdp
>
> Example json output for `token show`:
> {
> "token_info": "/sys/fs/bpf/token",
> "allowed_cmds": ["map_create","prog_load"
> ],
> "allowed_maps":
This is not valid JSON. You're missing a value for "allowed_maps" (here
it should likely be an empty array), and the comma:
"allowed_maps": [],
> "allowed_progs": ["kprobe"
> ],
> "allowed_attachs": ["xdp"
> ]
> }
>
> Signed-off-by: Tao Chen <chen.dylane@xxxxxxxxx>
> ---
> tools/bpf/bpftool/main.c | 3 +-
> tools/bpf/bpftool/main.h | 1 +
> tools/bpf/bpftool/token.c | 229 ++++++++++++++++++++++++++++++++++++++
> 3 files changed, 232 insertions(+), 1 deletion(-)
> create mode 100644 tools/bpf/bpftool/token.c
>
> diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
> index 2b7f2bd3a7d..0f1183b2ed0 100644
> --- a/tools/bpf/bpftool/main.c
> +++ b/tools/bpf/bpftool/main.c
> @@ -61,7 +61,7 @@ static int do_help(int argc, char **argv)
> " %s batch file FILE\n"
> " %s version\n"
> "\n"
> - " OBJECT := { prog | map | link | cgroup | perf | net | feature | btf | gen | struct_ops | iter }\n"
> + " OBJECT := { prog | map | link | cgroup | perf | net | feature | btf | gen | struct_ops | iter | token }\n"
> " " HELP_SPEC_OPTIONS " |\n"
> " {-V|--version} }\n"
> "",
> @@ -87,6 +87,7 @@ static const struct cmd commands[] = {
> { "gen", do_gen },
> { "struct_ops", do_struct_ops },
> { "iter", do_iter },
> + { "token", do_token },
> { "version", do_version },
> { 0 }
> };
> diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
> index 6db704fda5c..a2bb0714b3d 100644
> --- a/tools/bpf/bpftool/main.h
> +++ b/tools/bpf/bpftool/main.h
> @@ -166,6 +166,7 @@ int do_tracelog(int argc, char **arg) __weak;
> int do_feature(int argc, char **argv) __weak;
> int do_struct_ops(int argc, char **argv) __weak;
> int do_iter(int argc, char **argv) __weak;
> +int do_token(int argc, char **argv) __weak;
>
> int parse_u32_arg(int *argc, char ***argv, __u32 *val, const char *what);
> int prog_parse_fd(int *argc, char ***argv);
> diff --git a/tools/bpf/bpftool/token.c b/tools/bpf/bpftool/token.c
> new file mode 100644
> index 00000000000..2fcaff4f2ba
> --- /dev/null
> +++ b/tools/bpf/bpftool/token.c
> @@ -0,0 +1,229 @@
> +// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +
> +#ifndef _GNU_SOURCE
> +#define _GNU_SOURCE
> +#endif
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <stdbool.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <mntent.h>
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +
> +#include "json_writer.h"
> +#include "main.h"
> +
> +#define MOUNTS_FILE "/proc/mounts"
> +
> +#define zclose(fd) do { if (fd >= 0) close(fd); fd = -1; } while (0)
Seems unused?
> +
> +static bool has_delegate_options(const char *mnt_ops)
> +{
> + return strstr(mnt_ops, "delegate_cmds") != NULL ||
> + strstr(mnt_ops, "delegate_maps") != NULL ||
> + strstr(mnt_ops, "delegate_progs") != NULL ||
> + strstr(mnt_ops, "delegate_attachs") != NULL;
> +}
> +
> +static char *get_delegate_value(const char *opts, const char *key)
> +{
> + char *token, *rest, *ret = NULL;
> + char *opts_copy = strdup(opts);
> +
> + if (!opts_copy)
> + return NULL;
> +
> + for (token = strtok_r(opts_copy, ",", &rest); token != NULL;
> + token = strtok_r(NULL, ",", &rest)) {
> + if (strncmp(token, key, strlen(key)) == 0 &&
> + token[strlen(key)] == '=') {
> + ret = token + strlen(key) + 1;
> + break;
> + }
> + }
> + free(opts_copy);
> +
> + return ret;
> +}
> +
> +static void print_items_per_line(const char *input, int items_per_line)
> +{
> + char *str, *rest;
> + int cnt = 0;
> + char *strs = strdup(input);
> +
> + if (!strs)
> + return;
> +
> + for (str = strtok_r(strs, ":", &rest); str != NULL;
> + str = strtok_r(NULL, ":", &rest)) {
> + if (cnt % items_per_line == 0)
> + printf("\n\t");
> +
> + printf("%-20s", str);
> + cnt++;
> + }
> +
> + free(strs);
> +}
> +
> +#define ITEMS_PER_LINE 4
> +static void show_token_info_plain(struct mntent *mntent)
> +{
> + char *value;
> +
> + printf("\ntoken_info:");
> + printf("\n\t%s\n", mntent->mnt_dir);
> +
> + printf("\nallowed_cmds:");
> + value = get_delegate_value(mntent->mnt_opts, "delegate_cmds");
> + if (value)
> + print_items_per_line(value, ITEMS_PER_LINE);
> + printf("\n");
> +
> + printf("\nallowed_maps:");
> + value = get_delegate_value(mntent->mnt_opts, "delegate_maps");
> + if (value)
> + print_items_per_line(value, ITEMS_PER_LINE);
> + printf("\n");
> +
> + printf("\nallowed_progs:");
> + value = get_delegate_value(mntent->mnt_opts, "delegate_progs");
> + if (value)
> + print_items_per_line(value, ITEMS_PER_LINE);
> + printf("\n");
> +
> + printf("\nallowed_attachs:");
> + value = get_delegate_value(mntent->mnt_opts, "delegate_attachs");
> + if (value)
> + print_items_per_line(value, ITEMS_PER_LINE);
> + printf("\n");
> +}
> +
> +static void __json_array_str(const char *input)
Nit: Why the double underscore in the function name? Let's use a more
explicit name also, maybe something like "split_to_json_array"?
> +{
> + char *str, *rest;
> + char *strs = strdup(input);
> +
> + if (!strs)
> + return;
> +
> + jsonw_start_array(json_wtr);
> + for (str = strtok_r(strs, ":", &rest); str != NULL;
> + str = strtok_r(NULL, ":", &rest)) {
> + jsonw_string(json_wtr, str);
> + }
> + jsonw_end_array(json_wtr);
> +
> + free(strs);
> +}
> +
> +static void show_token_info_json(struct mntent *mntent)
> +{
> + char *value;
> +
> + jsonw_start_object(json_wtr);
> +
> + jsonw_string_field(json_wtr, "token_info", mntent->mnt_dir);
> +
> + jsonw_name(json_wtr, "allowed_cmds");
> + value = get_delegate_value(mntent->mnt_opts, "delegate_cmds");
> + if (value)
> + __json_array_str(value);
As mentioned above, you need to change __json_array_str() to print
something when you don't get a "value" here - just have it print an
empty array.
> +
> + jsonw_name(json_wtr, "allowed_maps");
> + value = get_delegate_value(mntent->mnt_opts, "delegate_maps");
> + if (value)
> + __json_array_str(value);
> +
> + jsonw_name(json_wtr, "allowed_progs");
> + value = get_delegate_value(mntent->mnt_opts, "delegate_progs");
> + if (value)
> + __json_array_str(value);
> +
> + jsonw_name(json_wtr, "allowed_attachs");
> + value = get_delegate_value(mntent->mnt_opts, "delegate_attachs");
> + if (value)
> + __json_array_str(value);
> +
> + jsonw_end_object(json_wtr);
> +}
> +
> +static int __show_token_info(struct mntent *mntent)
> +{
> +
> + if (json_output)
> + show_token_info_json(mntent);
> + else
> + show_token_info_plain(mntent);
> +
> + return 0;
> +}
> +
> +static int show_token_info(void)
> +{
> + FILE *fp;
> + struct mntent *ent;
> + bool hit = false;
> +
> + fp = setmntent(MOUNTS_FILE, "r");
> + if (!fp) {
> + p_err("Failed to open:%s", MOUNTS_FILE);
Missing space after the colon, in the error message.
> + return -1;
> + }
> +
> + while ((ent = getmntent(fp)) != NULL) {
> + if (strcmp(ent->mnt_type, "bpf") == 0) {
File common.c has:
if (strncmp(mntent->mnt_type, "bpf", 3) != 0)
continue;
Maybe do the same for consistency, and to avoid indenting too far right?
> + if (has_delegate_options(ent->mnt_opts)) {
> + hit = true;
> + break;
Apologies, my knowledge of BPF tokens is limited. Can you have only one
token exposed through a bpffs at a time? Asking because I know you can
have several bpffs on your system, if each can have delegate options
then why stop after the first bpffs mount point you find?
> + }
> + }
> + }
> +
> + if (hit)
> + __show_token_info(ent);
Maybe at least a p_info() message if you don't find anything to print?
> + endmntent(fp);
> +
> + return 0;
> +}
> +
> +static int do_show(int argc, char **argv)
> +{
> + if (argc)
> + return BAD_ARG();
> +
> + return show_token_info();
> +}
> +
> +static int do_help(int argc, char **argv)
> +{
> + if (json_output) {
> + jsonw_null(json_wtr);
> + return 0;
> + }
> +
> + fprintf(stderr,
> + "Usage: %1$s %2$s { show | list }\n"
> + " %1$s %2$s help\n"
> + "\n"
> + "",
> + bin_name, argv[-2]);
> + return 0;
> +}
> +
> +static const struct cmd cmds[] = {
> + { "show", do_show },
> + { "help", do_help },
> + { "list", do_show },
Nit: Can we have "help" coming third, below both "show" and "list" please?
> + { 0 }
> +};
> +
> +int do_token(int argc, char **argv)
> +{
> + return cmd_select(cmds, argc, argv, do_help);
> +}
