Messages in this thread | | | Date | Thu, 5 Jul 2018 19:01:16 -0700 | From | Jakub Kicinski <> | Subject | Re: [PATCH bpf-next 1/2] bpftool: introduce cgroup tree command |
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On Thu, 5 Jul 2018 18:05:20 -0700, Roman Gushchin wrote: > This commit introduces a new bpftool command: cgroup tree. > The idea is to iterate over the whole cgroup tree and print > all attached programs. > > I was debugging a bpf/systemd issue, and found, that there is > no simple way to listen all bpf programs attached to cgroups. > I did master something in bash, but after some time got tired of it, > and decided, that adding a dedicated bpftool command could be > a better idea. > > So, here it is: > $ sudo ./bpftool cgroup tree > CgroupPath > ID AttachType AttachFlags Name > /sys/fs/cgroup/system.slice/systemd-machined.service > 18 ingress > 17 egress > /sys/fs/cgroup/system.slice/systemd-logind.service > 20 ingress > 19 egress > /sys/fs/cgroup/system.slice/systemd-udevd.service > 16 ingress > 15 egress > /sys/fs/cgroup/system.slice/systemd-journald.service > 14 ingress > 13 egress > > Signed-off-by: Roman Gushchin <guro@fb.com> > Cc: Jakub Kicinski <jakub.kicinski@netronome.com> > Cc: Quentin Monnet <quentin.monnet@netronome.com> > Cc: Daniel Borkmann <daniel@iogearbox.net> > Cc: Alexei Starovoitov <ast@kernel.org>
Looks very useful! Minor nits/questions below. I think the reverse mapping could also be interesting - similar to how -f flag shows where program is pinned, we could add a flag which in
# bpftool prog show/list
adds info about cgroups where the program is attached? Obviously as a future extension.
> diff --git a/tools/bpf/bpftool/cgroup.c b/tools/bpf/bpftool/cgroup.c > index 16bee011e16c..125d5b6db568 100644 > --- a/tools/bpf/bpftool/cgroup.c > +++ b/tools/bpf/bpftool/cgroup.c > @@ -2,7 +2,12 @@ > // Copyright (C) 2017 Facebook > // Author: Roman Gushchin <guro@fb.com> > > +#define _XOPEN_SOURCE 500 > +#include <errno.h> > #include <fcntl.h> > +#include <ftw.h> > +#include <mntent.h> > +#include <stdio.h> > #include <stdlib.h> > #include <string.h> > #include <sys/stat.h> > @@ -53,7 +58,8 @@ static enum bpf_attach_type parse_attach_type(const char *str) > } > > static int show_bpf_prog(int id, const char *attach_type_str, > - const char *attach_flags_str) > + const char *attach_flags_str, > + int level) > { > struct bpf_prog_info info = {}; > __u32 info_len = sizeof(info); > @@ -78,7 +84,8 @@ static int show_bpf_prog(int id, const char *attach_type_str, > jsonw_string_field(json_wtr, "name", info.name); > jsonw_end_object(json_wtr); > } else { > - printf("%-8u %-15s %-15s %-15s\n", info.id, > + printf("%s%-8u %-15s %-15s %-15s\n", level ? " " : "", > + info.id, > attach_type_str, > attach_flags_str, > info.name); > @@ -88,7 +95,20 @@ static int show_bpf_prog(int id, const char *attach_type_str, > return 0; > } > > -static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type) > +static int count_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type) > +{ > + __u32 prog_cnt = 0; > + int ret; > + > + ret = bpf_prog_query(cgroup_fd, type, 0, NULL, NULL, &prog_cnt); > + if (ret) > + return -1; > + > + return prog_cnt; > +} > + > +static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type, > + int level) > { > __u32 prog_ids[1024] = {0}; > char *attach_flags_str; > @@ -123,7 +143,7 @@ static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type) > > for (iter = 0; iter < prog_cnt; iter++) > show_bpf_prog(prog_ids[iter], attach_type_strings[type], > - attach_flags_str); > + attach_flags_str, level); > > return 0; > } > @@ -161,7 +181,7 @@ static int do_show(int argc, char **argv) > * If we were able to get the show for at least one > * attach type, let's return 0. > */ > - if (show_attached_bpf_progs(cgroup_fd, type) == 0) > + if (show_attached_bpf_progs(cgroup_fd, type, 0) == 0) > ret = 0; > } > > @@ -173,6 +193,123 @@ static int do_show(int argc, char **argv) > return ret; > } > > +static int do_show_tree_fn(const char *fpath, const struct stat *sb, > + int typeflag, struct FTW *ftw) > +{ > + enum bpf_attach_type type; > + bool skip = true; > + int cgroup_fd; > + > + if (typeflag != FTW_D) > + return 0; > + > + cgroup_fd = open(fpath, O_RDONLY); > + if (cgroup_fd < 0) { > + p_err("can't open cgroup %s: %s", fpath, strerror(errno)); > + return -1; > + } > + > + for (type = 0; type < __MAX_BPF_ATTACH_TYPE; type++) { > + int count = count_attached_bpf_progs(cgroup_fd, type); > + > + if (count < 0 && errno != EINVAL) { > + p_err("can't query bpf programs attached to %s: %s", > + fpath, strerror(errno)); > + close(cgroup_fd); > + return -1; > + } > + if (count > 0) { > + skip = false; > + break; > + } > + } > + > + if (skip) { > + close(cgroup_fd); > + return 0; > + } > + > + if (json_output) { > + jsonw_start_object(json_wtr); > + jsonw_string_field(json_wtr, "cgroup", fpath); > + jsonw_name(json_wtr, "programs"); > + jsonw_start_array(json_wtr); > + } else { > + printf("%s\n", fpath); > + } > + > + for (type = 0; type < __MAX_BPF_ATTACH_TYPE; type++) > + show_attached_bpf_progs(cgroup_fd, type, ftw->level); > + > + if (json_output) { > + jsonw_end_array(json_wtr); > + jsonw_end_object(json_wtr); > + } > + > + close(cgroup_fd); > + > + return 0; > +} > + > +static char *find_cgroup_root(void) > +{ > + struct mntent *mnt; > + FILE *f; > + > + f = fopen("/proc/mounts", "r"); > + if (f == NULL) > + return NULL; > + > + while ((mnt = getmntent(f))) { > + if (strcmp(mnt->mnt_type, "cgroup2") == 0) { > + fclose(f); > + return strdup(mnt->mnt_dir);
FWIW you don't free this memory.
> + } > + } > + > + fclose(f); > + return NULL; > +} > + > +static int do_show_tree(int argc, char **argv) > +{ > + char *cgroup_root; > + int ret; > + > + if (argc > 1) { > + p_err("too many parameters for cgroup tree"); > + return -1; > + } > + > + if (argc == 1) { > + cgroup_root = argv[0]; > + } else { > + cgroup_root = find_cgroup_root(); > + > + if (!cgroup_root) { > + p_err("cgroup v2 isn't mounted"); > + return -1; > + } > + } > + > + if (json_output) > + jsonw_start_array(json_wtr); > + else > + printf("%s\n" > + "%-8s %-15s %-15s %-15s\n", > + "CgroupPath", > + "ID", "AttachType", "AttachFlags", "Name"); > + > + ret = nftw(cgroup_root, do_show_tree_fn, 1024, FTW_MOUNT); > + if (ret && errno == ENOENT) > + p_err("can't iterate over %s: %s", cgroup_root, > + strerror(errno));
I'm worried this could lead to a duplicated error in JSON output, no? Is it possible that do_show_tree_fn() would have already printed an error?
> + > + if (json_output) > + jsonw_end_array(json_wtr); > + > + return ret; > +} > + > static int do_attach(int argc, char **argv) > { > enum bpf_attach_type attach_type; > @@ -289,6 +426,7 @@ static int do_help(int argc, char **argv) > > fprintf(stderr, > "Usage: %s %s { show | list } CGROUP\n" > + " %s %s tree [CGROUP_ROOT]\n" > " %s %s attach CGROUP ATTACH_TYPE PROG [ATTACH_FLAGS]\n" > " %s %s detach CGROUP ATTACH_TYPE PROG\n" > " %s %s help\n" > @@ -298,6 +436,7 @@ static int do_help(int argc, char **argv) > " " HELP_SPEC_PROGRAM "\n" > " " HELP_SPEC_OPTIONS "\n" > "", > + bin_name, argv[-2], > bin_name, argv[-2], bin_name, argv[-2], > bin_name, argv[-2], bin_name, argv[-2]); > > @@ -307,6 +446,7 @@ static int do_help(int argc, char **argv) > static const struct cmd cmds[] = { > { "show", do_show }, > { "list", do_show }, > + { "tree", do_show_tree }, > { "attach", do_attach }, > { "detach", do_detach }, > { "help", do_help },
Could you please also add this new command to bash completions? It should be fairly trivial to handle.
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