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tools: bpftool: add support for reporting the effective cgroup progs

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Takshak said in the original submission:

With different bpf attach_flags available to attach bpf programs specially
with BPF_F_ALLOW_OVERRIDE and BPF_F_ALLOW_MULTI, the list of effective
bpf-programs available to any sub-cgroups really needs to be available for
easy debugging.

Using BPF_F_QUERY_EFFECTIVE flag, one can get the list of not only attached
bpf-programs to a cgroup but also the inherited ones from parent cgroup.

So a new option is introduced to use BPF_F_QUERY_EFFECTIVE query flag here
to list all the effective bpf-programs available for execution at a specified
cgroup.

Reused modified test program test_cgroup_attach from tools/testing/selftests/bpf:
  # ./test_cgroup_attach

With old bpftool:

 # bpftool cgroup show /sys/fs/cgroup/cgroup-test-work-dir/cg1/
  ID       AttachType      AttachFlags     Name
  271      egress          multi           pkt_cntr_1
  272      egress          multi           pkt_cntr_2

Attached new program pkt_cntr_4 in cg2 gives following:

 # bpftool cgroup show /sys/fs/cgroup/cgroup-test-work-dir/cg1/cg2
  ID       AttachType      AttachFlags     Name
  273      egress          override        pkt_cntr_4

And with new "effective" option it shows all effective programs for cg2:

 # bpftool cgroup show /sys/fs/cgroup/cgroup-test-work-dir/cg1/cg2 effective
  ID       AttachType      AttachFlags     Name
  273      egress          override        pkt_cntr_4
  271      egress          override        pkt_cntr_1
  272      egress          override        pkt_cntr_2

Compared to original submission use a local flag instead of global
option.

We need to clear query_flags on every command, in case batch mode
wants to use varying settings.

v2: (Takshak)
 - forbid duplicated flags;
 - fix cgroup path freeing.

Signed-off-by: Takshak Chahande <ctakshak@fb.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Takshak Chahande <ctakshak@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Jakub Kicinski 2019-07-30 14:03:00 -07:00 committed by Alexei Starovoitov
parent bf8ff0f8cf
commit a98bf57391
3 changed files with 76 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
tools/bpf/bpftool/Documentation/bpftool-cgroup.rst
View File

@ -20,8 +20,8 @@ SYNOPSIS
CGROUP COMMANDS
===============
| **bpftool** **cgroup { show | list }** *CGROUP*
| **bpftool** **cgroup tree** [*CGROUP_ROOT*]
| **bpftool** **cgroup { show | list }** *CGROUP* [**effective**]
| **bpftool** **cgroup tree** [*CGROUP_ROOT*] [**effective**]
| **bpftool** **cgroup attach** *CGROUP* *ATTACH_TYPE* *PROG* [*ATTACH_FLAGS*]
| **bpftool** **cgroup detach** *CGROUP* *ATTACH_TYPE* *PROG*
| **bpftool** **cgroup help**
@ -35,13 +35,17 @@ CGROUP COMMANDS
DESCRIPTION
===========
**bpftool cgroup { show | list }** *CGROUP*
**bpftool cgroup { show | list }** *CGROUP* [**effective**]
List all programs attached to the cgroup *CGROUP*.
Output will start with program ID followed by attach type,
attach flags and program name.
**bpftool cgroup tree** [*CGROUP_ROOT*]
If **effective** is specified retrieve effective programs that
will execute for events within a cgroup. This includes
inherited along with attached ones.
**bpftool cgroup tree** [*CGROUP_ROOT*] [**effective**]
Iterate over all cgroups in *CGROUP_ROOT* and list all
attached programs. If *CGROUP_ROOT* is not specified,
bpftool uses cgroup v2 mountpoint.
@ -50,6 +54,10 @@ DESCRIPTION
commands: it starts with absolute cgroup path, followed by
program ID, attach type, attach flags and program name.
If **effective** is specified retrieve effective programs that
will execute for events within a cgroup. This includes
inherited along with attached ones.
**bpftool cgroup attach** *CGROUP* *ATTACH_TYPE* *PROG* [*ATTACH_FLAGS*]
Attach program *PROG* to the cgroup *CGROUP* with attach type
*ATTACH_TYPE* and optional *ATTACH_FLAGS*.

15
tools/bpf/bpftool/bash-completion/bpftool
View File

@ -710,12 +710,15 @@ _bpftool()
;;
cgroup)
case $command in
show|list)
_filedir
return 0
;;
tree)
_filedir
show|list|tree)
case $cword in
3)
_filedir
;;
4)
COMPREPLY=( $( compgen -W 'effective' -- "$cur" ) )
;;
esac
return 0
;;
attach|detach)

83
tools/bpf/bpftool/cgroup.c
View File

@ -29,6 +29,8 @@
" recvmsg4 | recvmsg6 | sysctl |\n" \
" getsockopt | setsockopt }"
static unsigned int query_flags;
static const char * const attach_type_strings[] = {
[BPF_CGROUP_INET_INGRESS] = "ingress",
[BPF_CGROUP_INET_EGRESS] = "egress",
@ -107,7 +109,8 @@ 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);
ret = bpf_prog_query(cgroup_fd, type, query_flags, NULL,
NULL, &prog_cnt);
if (ret)
return -1;
@ -125,8 +128,8 @@ static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type,
int ret;
prog_cnt = ARRAY_SIZE(prog_ids);
ret = bpf_prog_query(cgroup_fd, type, 0, &attach_flags, prog_ids,
&prog_cnt);
ret = bpf_prog_query(cgroup_fd, type, query_flags, &attach_flags,
prog_ids, &prog_cnt);
if (ret)
return ret;
@ -158,20 +161,34 @@ static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type,
static int do_show(int argc, char **argv)
{
enum bpf_attach_type type;
const char *path;
int cgroup_fd;
int ret = -1;
if (argc < 1) {
p_err("too few parameters for cgroup show");
goto exit;
} else if (argc > 1) {
p_err("too many parameters for cgroup show");
goto exit;
query_flags = 0;
if (!REQ_ARGS(1))
return -1;
path = GET_ARG();
while (argc) {
if (is_prefix(*argv, "effective")) {
if (query_flags & BPF_F_QUERY_EFFECTIVE) {
p_err("duplicated argument: %s", *argv);
return -1;
}
query_flags |= BPF_F_QUERY_EFFECTIVE;
NEXT_ARG();
} else {
p_err("expected no more arguments, 'effective', got: '%s'?",
*argv);
return -1;
}
}
cgroup_fd = open(argv[0], O_RDONLY);
cgroup_fd = open(path, O_RDONLY);
if (cgroup_fd < 0) {
p_err("can't open cgroup %s", argv[0]);
p_err("can't open cgroup %s", path);
goto exit;
}
@ -294,25 +311,36 @@ static char *find_cgroup_root(void)
static int do_show_tree(int argc, char **argv)
{
char *cgroup_root;
char *cgroup_root, *cgroup_alloced = NULL;
int ret;
switch (argc) {
case 0:
cgroup_root = find_cgroup_root();
if (!cgroup_root) {
query_flags = 0;
if (!argc) {
cgroup_alloced = find_cgroup_root();
if (!cgroup_alloced) {
p_err("cgroup v2 isn't mounted");
return -1;
}
break;
case 1:
cgroup_root = argv[0];
break;
default:
p_err("too many parameters for cgroup tree");
return -1;
}
cgroup_root = cgroup_alloced;
} else {
cgroup_root = GET_ARG();
while (argc) {
if (is_prefix(*argv, "effective")) {
if (query_flags & BPF_F_QUERY_EFFECTIVE) {
p_err("duplicated argument: %s", *argv);
return -1;
}
query_flags |= BPF_F_QUERY_EFFECTIVE;
NEXT_ARG();
} else {
p_err("expected no more arguments, 'effective', got: '%s'?",
*argv);
return -1;
}
}
}
if (json_output)
jsonw_start_array(json_wtr);
@ -338,8 +366,7 @@ static int do_show_tree(int argc, char **argv)
if (json_output)
jsonw_end_array(json_wtr);
if (argc == 0)
free(cgroup_root);
free(cgroup_alloced);
return ret;
}
@ -459,8 +486,8 @@ static int do_help(int argc, char **argv)
}
fprintf(stderr,
"Usage: %s %s { show | list } CGROUP\n"
" %s %s tree [CGROUP_ROOT]\n"
"Usage: %s %s { show | list } CGROUP [**effective**]\n"
" %s %s tree [CGROUP_ROOT] [**effective**]\n"
" %s %s attach CGROUP ATTACH_TYPE PROG [ATTACH_FLAGS]\n"
" %s %s detach CGROUP ATTACH_TYPE PROG\n"
" %s %s help\n"