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linux-next/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst
Jakub Kicinski a98bf57391 tools: bpftool: add support for reporting the effective cgroup progs
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>
2019-07-30 21:15:02 -07:00

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ReStructuredText

================
bpftool-cgroup
================
-------------------------------------------------------------------------------
tool for inspection and simple manipulation of eBPF progs
-------------------------------------------------------------------------------
:Manual section: 8
SYNOPSIS
========
**bpftool** [*OPTIONS*] **cgroup** *COMMAND*
*OPTIONS* := { { **-j** | **--json** } [{ **-p** | **--pretty** }] | { **-f** | **--bpffs** } }
*COMMANDS* :=
{ **show** | **list** | **tree** | **attach** | **detach** | **help** }
CGROUP COMMANDS
===============
| **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**
|
| *PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* }
| *ATTACH_TYPE* := { **ingress** | **egress** | **sock_create** | **sock_ops** | **device** |
| **bind4** | **bind6** | **post_bind4** | **post_bind6** | **connect4** | **connect6** |
| **sendmsg4** | **sendmsg6** | **recvmsg4** | **recvmsg6** | **sysctl** |
| **getsockopt** | **setsockopt** }
| *ATTACH_FLAGS* := { **multi** | **override** }
DESCRIPTION
===========
**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.
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.
The output is similar to the output of cgroup show/list
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*.
*ATTACH_FLAGS* can be one of: **override** if a sub-cgroup installs
some bpf program, the program in this cgroup yields to sub-cgroup
program; **multi** if a sub-cgroup installs some bpf program,
that cgroup program gets run in addition to the program in this
cgroup.
Only one program is allowed to be attached to a cgroup with
no attach flags or the **override** flag. Attaching another
program will release old program and attach the new one.
Multiple programs are allowed to be attached to a cgroup with
**multi**. They are executed in FIFO order (those that were
attached first, run first).
Non-default *ATTACH_FLAGS* are supported by kernel version 4.14
and later.
*ATTACH_TYPE* can be on of:
**ingress** ingress path of the inet socket (since 4.10);
**egress** egress path of the inet socket (since 4.10);
**sock_create** opening of an inet socket (since 4.10);
**sock_ops** various socket operations (since 4.12);
**device** device access (since 4.15);
**bind4** call to bind(2) for an inet4 socket (since 4.17);
**bind6** call to bind(2) for an inet6 socket (since 4.17);
**post_bind4** return from bind(2) for an inet4 socket (since 4.17);
**post_bind6** return from bind(2) for an inet6 socket (since 4.17);
**connect4** call to connect(2) for an inet4 socket (since 4.17);
**connect6** call to connect(2) for an inet6 socket (since 4.17);
**sendmsg4** call to sendto(2), sendmsg(2), sendmmsg(2) for an
unconnected udp4 socket (since 4.18);
**sendmsg6** call to sendto(2), sendmsg(2), sendmmsg(2) for an
unconnected udp6 socket (since 4.18);
**recvmsg4** call to recvfrom(2), recvmsg(2), recvmmsg(2) for
an unconnected udp4 socket (since 5.2);
**recvmsg6** call to recvfrom(2), recvmsg(2), recvmmsg(2) for
an unconnected udp6 socket (since 5.2);
**sysctl** sysctl access (since 5.2);
**getsockopt** call to getsockopt (since 5.3);
**setsockopt** call to setsockopt (since 5.3).
**bpftool cgroup detach** *CGROUP* *ATTACH_TYPE* *PROG*
Detach *PROG* from the cgroup *CGROUP* and attach type
*ATTACH_TYPE*.
**bpftool prog help**
Print short help message.
OPTIONS
=======
-h, --help
Print short generic help message (similar to **bpftool help**).
-V, --version
Print version number (similar to **bpftool version**).
-j, --json
Generate JSON output. For commands that cannot produce JSON, this
option has no effect.
-p, --pretty
Generate human-readable JSON output. Implies **-j**.
-f, --bpffs
Show file names of pinned programs.
-d, --debug
Print all logs available from libbpf, including debug-level
information.
EXAMPLES
========
|
| **# mount -t bpf none /sys/fs/bpf/**
| **# mkdir /sys/fs/cgroup/test.slice**
| **# bpftool prog load ./device_cgroup.o /sys/fs/bpf/prog**
| **# bpftool cgroup attach /sys/fs/cgroup/test.slice/ device id 1 allow_multi**
**# bpftool cgroup list /sys/fs/cgroup/test.slice/**
::
ID AttachType AttachFlags Name
1 device allow_multi bpf_prog1
|
| **# bpftool cgroup detach /sys/fs/cgroup/test.slice/ device id 1**
| **# bpftool cgroup list /sys/fs/cgroup/test.slice/**
::
ID AttachType AttachFlags Name
SEE ALSO
========
**bpf**\ (2),
**bpf-helpers**\ (7),
**bpftool**\ (8),
**bpftool-prog**\ (8),
**bpftool-map**\ (8),
**bpftool-feature**\ (8),
**bpftool-net**\ (8),
**bpftool-perf**\ (8),
**bpftool-btf**\ (8)