Commit graph

6 commits

Author SHA1 Message Date
Yonghong Song
00fa1d83a8 bpftool: Handle EAGAIN error code properly in pids collection
When the error code is EAGAIN, the kernel signals the user
space should retry the read() operation for bpf iterators.
Let us do it.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200818222312.2181675-1-yhs@fb.com
2020-08-18 17:36:23 -07:00
Andrii Nakryiko
93776cb9ee tools/bpftool: Remove warning about PID iterator support
Don't emit warning that bpftool was built without PID iterator support. This
error garbles JSON output of otherwise perfectly valid show commands.

Reported-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200710232605.20918-1-andriin@fb.com
2020-07-13 15:41:05 -07:00
Louis Peens
625eb8e85e bpf: Fix another bpftool segfault without skeleton code enabled
emit_obj_refs_json needs to added the same as with emit_obj_refs_plain
to prevent segfaults, similar to Commit "8ae4121bd89e bpf: Fix bpftool
without skeleton code enabled"). See the error below:

    # ./bpftool -p prog
    {
        "error": "bpftool built without PID iterator support"
    },[{
            "id": 2,
            "type": "cgroup_skb",
            "tag": "7be49e3934a125ba",
            "gpl_compatible": true,
            "loaded_at": 1594052789,
            "uid": 0,
            "bytes_xlated": 296,
            "jited": true,
            "bytes_jited": 203,
            "bytes_memlock": 4096,
            "map_ids": [2,3
    Segmentation fault (core dumped)

The same happens for ./bpftool -p map, as well as ./bpftool -j prog/map.

Fixes: d53dee3fe0 ("tools/bpftool: Show info for processes holding BPF map/prog/link/btf FDs")
Signed-off-by: Louis Peens <louis.peens@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200708110827.7673-1-louis.peens@netronome.com
2020-07-09 00:32:00 +02:00
John Fastabend
8ae4121bd8 bpf: Fix bpftool without skeleton code enabled
Fix segfault from bpftool by adding emit_obj_refs_plain when skeleton
code is disabled.

Tested by deleting BUILD_BPF_SKELS in Makefile. We found this doing
backports for Cilium when a testing image pulled in latest bpf-next
bpftool, but kept using an older clang-7.

  # ./bpftool prog show
  Error: bpftool built without PID iterator support
  3: cgroup_skb  tag 7be49e3934a125ba  gpl
          loaded_at 2020-07-01T08:01:29-0700  uid 0
  Segmentation fault

Fixes: d53dee3fe0 ("tools/bpftool: Show info for processes holding BPF map/prog/link/btf FDs")
Reported-by: Joe Stringer <joe@wand.net.nz>
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/159375071997.14984.17404504293832961401.stgit@john-XPS-13-9370
2020-07-03 23:20:40 +02:00
Quentin Monnet
54b66c2255 tools, bpftool: Fix variable shadowing in emit_obj_refs_json()
Building bpftool yields the following complaint:

    pids.c: In function 'emit_obj_refs_json':
    pids.c:175:80: warning: declaration of 'json_wtr' shadows a global declaration [-Wshadow]
      175 | void emit_obj_refs_json(struct obj_refs_table *table, __u32 id, json_writer_t *json_wtr)
          |                                                                 ~~~~~~~~~~~~~~~^~~~~~~~
    In file included from pids.c:11:
    main.h:141:23: note: shadowed declaration is here
      141 | extern json_writer_t *json_wtr;
          |                       ^~~~~~~~

Let's rename the variable.

v2:
- Rename the variable instead of calling the global json_wtr directly.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200623213600.16643-1-quentin@isovalent.com
2020-06-24 15:46:28 +02:00
Andrii Nakryiko
d53dee3fe0 tools/bpftool: Show info for processes holding BPF map/prog/link/btf FDs
Add bpf_iter-based way to find all the processes that hold open FDs against
BPF object (map, prog, link, btf). bpftool always attempts to discover this,
but will silently give up if kernel doesn't yet support bpf_iter BPF programs.
Process name and PID are emitted for each process (task group).

Sample output for each of 4 BPF objects:

$ sudo ./bpftool prog show
2694: cgroup_device  tag 8c42dee26e8cd4c2  gpl
        loaded_at 2020-06-16T15:34:32-0700  uid 0
        xlated 648B  jited 409B  memlock 4096B
        pids systemd(1)
2907: cgroup_skb  name egress  tag 9ad187367cf2b9e8  gpl
        loaded_at 2020-06-16T18:06:54-0700  uid 0
        xlated 48B  jited 59B  memlock 4096B  map_ids 2436
        btf_id 1202
        pids test_progs(2238417), test_progs(2238445)

$ sudo ./bpftool map show
2436: array  name test_cgr.bss  flags 0x400
        key 4B  value 8B  max_entries 1  memlock 8192B
        btf_id 1202
        pids test_progs(2238417), test_progs(2238445)
2445: array  name pid_iter.rodata  flags 0x480
        key 4B  value 4B  max_entries 1  memlock 8192B
        btf_id 1214  frozen
        pids bpftool(2239612)

$ sudo ./bpftool link show
61: cgroup  prog 2908
        cgroup_id 375301  attach_type egress
        pids test_progs(2238417), test_progs(2238445)
62: cgroup  prog 2908
        cgroup_id 375344  attach_type egress
        pids test_progs(2238417), test_progs(2238445)

$ sudo ./bpftool btf show
1202: size 1527B  prog_ids 2908,2907  map_ids 2436
        pids test_progs(2238417), test_progs(2238445)
1242: size 34684B
        pids bpftool(2258892)

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200619231703.738941-9-andriin@fb.com
2020-06-22 17:01:49 -07:00