| Message ID | 20191218173827.20584-1-cneirabustos@gmail.com |
|---|---|
| Headers | show |
| Series | BPF: New helper to obtain namespace data from current task | expand |
On Wed, Dec 18, 2019 at 9:38 AM Carlos Neira <cneirabustos@gmail.com> wrote: > > Currently bpf_get_current_pid_tgid(), is used to do pid filtering in bcc's > scripts but this helper returns the pid as seen by the root namespace which is > fine when a bcc script is not executed inside a container. > When the process of interest is inside a container, pid filtering will not work > if bpf_get_current_pid_tgid() is used. > This helper addresses this limitation returning the pid as it's seen by the current > namespace where the script is executing. > > In the future different pid_ns files may belong to different devices, according to the > discussion between Eric Biederman and Yonghong in 2017 Linux plumbers conference. > To address that situation the helper requires inum and dev_t from /proc/self/ns/pid. > This helper has the same use cases as bpf_get_current_pid_tgid() as it can be > used to do pid filtering even inside a container. I think the set looks like fine. Please respin against bpf-next carrying over Yonghong's ack and I'll apply it. Please squash patch 2 and 3 together. Updates to tools/uapi/bpf.h don't need to be separated anymore. Patch 5 can be squashed into them as well. Could you also improve selftest from patch 4 to test new helper both inside and outside of some container? With unshare(CLONE_NEWPID) or something. Do you have corresponding bcc change to show how it's going to be used?
On Thu, Jan 09, 2020 at 05:46:29PM -0800, Alexei Starovoitov wrote: > On Wed, Dec 18, 2019 at 9:38 AM Carlos Neira <cneirabustos@gmail.com> wrote: > > > > Currently bpf_get_current_pid_tgid(), is used to do pid filtering in bcc's > > scripts but this helper returns the pid as seen by the root namespace which is > > fine when a bcc script is not executed inside a container. > > When the process of interest is inside a container, pid filtering will not work > > if bpf_get_current_pid_tgid() is used. > > This helper addresses this limitation returning the pid as it's seen by the current > > namespace where the script is executing. > > > > In the future different pid_ns files may belong to different devices, according to the > > discussion between Eric Biederman and Yonghong in 2017 Linux plumbers conference. > > To address that situation the helper requires inum and dev_t from /proc/self/ns/pid. > > This helper has the same use cases as bpf_get_current_pid_tgid() as it can be > > used to do pid filtering even inside a container. > > I think the set looks like fine. Please respin against bpf-next > carrying over Yonghong's ack and I'll apply it. > Please squash patch 2 and 3 together. > Updates to tools/uapi/bpf.h don't need to be separated anymore. > Patch 5 can be squashed into them as well. > Could you also improve selftest from patch 4 to test new helper > both inside and outside of some container? > With unshare(CLONE_NEWPID) or something. > Do you have corresponding bcc change to show how it's going to be used? Thanks Alexei, I'll squash patches 2, 3, 5 together and improve the new helper test, regarding bcc changes, I also need to work on that as the one I created a while ago now is not valid https://github.com/iovisor/bcc/pull/1901/commits/a81b4352173cb82922d4d4bb965a39f781fd7693 Bests
Currently bpf_get_current_pid_tgid(), is used to do pid filtering in bcc's scripts but this helper returns the pid as seen by the root namespace which is fine when a bcc script is not executed inside a container. When the process of interest is inside a container, pid filtering will not work if bpf_get_current_pid_tgid() is used. This helper addresses this limitation returning the pid as it's seen by the current namespace where the script is executing. In the future different pid_ns files may belong to different devices, according to the discussion between Eric Biederman and Yonghong in 2017 Linux plumbers conference. To address that situation the helper requires inum and dev_t from /proc/self/ns/pid. This helper has the same use cases as bpf_get_current_pid_tgid() as it can be used to do pid filtering even inside a container. Signed-off-by: Carlos Neira <cneirabustos@gmail.com> Carlos Neira (5): fs/nsfs.c: added ns_match bpf: added new helper bpf_get_ns_current_pid_tgid tools: Added bpf_get_ns_current_pid_tgid helper tools/testing/selftests/bpf: Add self-tests for new helper bpf_get_ns_current_pid_tgid. bpf_helpers_doc.py: Add struct bpf_pidns_info to known types fs/nsfs.c | 14 +++ include/linux/bpf.h | 1 + include/linux/proc_ns.h | 2 + include/uapi/linux/bpf.h | 19 +++- kernel/bpf/core.c | 1 + kernel/bpf/helpers.c | 45 ++++++++++ kernel/trace/bpf_trace.c | 2 + scripts/bpf_helpers_doc.py | 1 + tools/include/uapi/linux/bpf.h | 19 +++- .../bpf/prog_tests/ns_current_pid_tgid.c | 88 +++++++++++++++++++ .../bpf/progs/test_ns_current_pid_tgid.c | 37 ++++++++ 11 files changed, 227 insertions(+), 2 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/ns_current_pid_tgid.c create mode 100644 tools/testing/selftests/bpf/progs/test_ns_current_pid_tgid.c