From: Javier Honduvilla Coto <javierhonduco@fb•com>
To: Daniel Borkmann <daniel@iogearbox•net>
Cc: "netdev@vger•kernel.org" <netdev@vger•kernel.org>,
Yonghong Song <yhs@fb•com>, Kernel Team <Kernel-team@fb•com>
Subject: Re: [PATCH v4 bpf-next 1/3] bpf: add bpf_progenyof helper
Date: Wed, 27 Mar 2019 16:02:32 +0000 [thread overview]
Message-ID: <20190327160227.GB63993@fb.com> (raw)
In-Reply-To: <123407cd-f439-7158-1c06-7cd6f10ba8e9@iogearbox.net>
On Mon, Mar 25, 2019 at 03:17:03PM +0100, Daniel Borkmann wrote:
> On 03/22/2019 11:38 PM, Javier Honduvilla Coto wrote:
> > This patch adds the bpf_progenyof helper which receives a PID and returns
> > 1 if the process currently being executed is in the process hierarchy
> > including itself or 0 if not.
> >
> > This is very useful in tracing programs when we want to filter by a
> > given PID and all the children it might spawn. The current workarounds
> > most people implement for this purpose have issues:
> >
> > - Attaching to process spawning syscalls and dynamically add those PIDs
> > to some bpf map that would be used to filter is cumbersome and
> > potentially racy.
> > - Unrolling some loop to perform what this helper is doing consumes lots
> > of instructions. That and the impossibility to jump backwards makes it
> > really hard to be correct in really large process chains.
> >
> > Signed-off-by: Javier Honduvilla Coto <javierhonduco@fb•com>
> > ---
> > include/linux/bpf.h | 1 +
> > include/uapi/linux/bpf.h | 10 +++++++++-
> > kernel/bpf/core.c | 1 +
> > kernel/bpf/helpers.c | 32 ++++++++++++++++++++++++++++++++
> > kernel/trace/bpf_trace.c | 2 ++
> > 5 files changed, 45 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> > index f62897198844..bd0d2b38e7d5 100644
> > --- a/include/linux/bpf.h
> > +++ b/include/linux/bpf.h
> > @@ -930,6 +930,7 @@ extern const struct bpf_func_proto bpf_sk_redirect_map_proto;
> > extern const struct bpf_func_proto bpf_spin_lock_proto;
> > extern const struct bpf_func_proto bpf_spin_unlock_proto;
> > extern const struct bpf_func_proto bpf_get_local_storage_proto;
> > +extern const struct bpf_func_proto bpf_progenyof_proto;
> >
> > /* Shared helpers among cBPF and eBPF. */
> > void bpf_user_rnd_init_once(void);
> > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > index 3c04410137d9..cf54cc739bf4 100644
> > --- a/include/uapi/linux/bpf.h
> > +++ b/include/uapi/linux/bpf.h
> > @@ -2463,6 +2463,13 @@ union bpf_attr {
> > * Return
> > * 0 if iph and th are a valid SYN cookie ACK, or a negative error
> > * otherwise.
> > + * int bpf_progenyof(int pid)
> > + * Description
> > + * This helper is useful in programs that want to filter events
> > + * happening to a pid of any of its descendants.
> > + * Return
> > + * 1 if the currently executing process' pid is in the process
> > + * hierarchy of the passed pid. 0 Otherwise.
>
> What about the -EINVAL?
>
> > */
> > #define __BPF_FUNC_MAPPER(FN) \
> > FN(unspec), \
> > @@ -2565,7 +2572,8 @@ union bpf_attr {
> > FN(skb_ecn_set_ce), \
> > FN(get_listener_sock), \
> > FN(skc_lookup_tcp), \
> > - FN(tcp_check_syncookie),
> > + FN(tcp_check_syncookie), \
> > + FN(progenyof),
> >
> > /* integer value in 'imm' field of BPF_CALL instruction selects which helper
> > * function eBPF program intends to call
> > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> > index ff09d32a8a1b..437986497468 100644
> > --- a/kernel/bpf/core.c
> > +++ b/kernel/bpf/core.c
> > @@ -2044,6 +2044,7 @@ const struct bpf_func_proto bpf_get_current_uid_gid_proto __weak;
> > const struct bpf_func_proto bpf_get_current_comm_proto __weak;
> > const struct bpf_func_proto bpf_get_current_cgroup_id_proto __weak;
> > const struct bpf_func_proto bpf_get_local_storage_proto __weak;
> > +const struct bpf_func_proto bpf_progenyof_proto __weak;
> >
> > const struct bpf_func_proto * __weak bpf_get_trace_printk_proto(void)
> > {
> > diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> > index a411fc17d265..f093b35d1ba8 100644
> > --- a/kernel/bpf/helpers.c
> > +++ b/kernel/bpf/helpers.c
> > @@ -18,6 +18,7 @@
> > #include <linux/sched.h>
> > #include <linux/uidgid.h>
> > #include <linux/filter.h>
> > +#include <linux/init_task.h>
> >
> > /* If kernel subsystem is allowing eBPF programs to call this function,
> > * inside its own verifier_ops->get_func_proto() callback it should return
> > @@ -364,3 +365,34 @@ const struct bpf_func_proto bpf_get_local_storage_proto = {
> > };
> > #endif
> > #endif
> > +
> > +BPF_CALL_1(bpf_progenyof, int, pid)
>
> Nit: could we add a more descriptive helper name? What's progenyof? Also s/int/pid_t/?
>
> > +{
> > + int result = 0;
> > + struct task_struct *task = current;
> > +
> > + WARN_ON(!rcu_read_lock_held());
>
> This is not needed since it's guaranteed in BPF.
Sure, thanks!
>
> > + if (unlikely(!task))
> > + return -EINVAL;
> > +
> > + if (pid == 0)
> > + return 1;
> > +
> > + while (task != &init_task) {
> > + if (task->pid == pid) {
> > + result = 1;
> > + break;
> > + }
> > + task = rcu_dereference(task->real_parent);
> > + }
> > +
> > + return result;
> > +}
> > +
> > +const struct bpf_func_proto bpf_progenyof_proto = {
> > + .func = bpf_progenyof,
> > + .gpl_only = false,
> > + .ret_type = RET_INTEGER,
> > + .arg1_type = ARG_ANYTHING,
> > +};
> > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> > index d64c00afceb5..e69283d423ff 100644
> > --- a/kernel/trace/bpf_trace.c
> > +++ b/kernel/trace/bpf_trace.c
> > @@ -599,6 +599,8 @@ tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> > return &bpf_get_prandom_u32_proto;
> > case BPF_FUNC_probe_read_str:
> > return &bpf_probe_read_str_proto;
> > + case BPF_FUNC_progenyof:
> > + return &bpf_progenyof_proto;
> > #ifdef CONFIG_CGROUPS
> > case BPF_FUNC_get_current_cgroup_id:
> > return &bpf_get_current_cgroup_id_proto;
> >
>
next prev parent reply other threads:[~2019-03-27 16:02 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-26 22:36 [PATCH bpf-next 0/3] bpf: add progenyof helper Javier Honduvilla Coto
2019-02-26 22:36 ` [PATCH bpf-next 1/3] bpf: add bpf_progenyof helper Javier Honduvilla Coto
2019-02-27 6:26 ` Martin Lau
2019-03-01 17:28 ` Javier Honduvilla Coto
2019-03-02 0:01 ` Martin Lau
2019-03-02 1:08 ` Javier Honduvilla Coto
2019-03-01 17:43 ` Javier Honduvilla Coto
2019-03-01 18:06 ` [PATCH v2 bpf-next 0/3] " Javier Honduvilla Coto
2019-03-01 18:06 ` [PATCH v2 bpf-next 1/3] " Javier Honduvilla Coto
2019-03-02 0:12 ` Martin Lau
2019-03-02 1:10 ` Javier Honduvilla Coto
2019-03-05 22:47 ` [PATCH v3 bpf-next 0/3] " Javier Honduvilla Coto
2019-03-05 22:47 ` [PATCH v3 bpf-next 1/3] " Javier Honduvilla Coto
2019-03-05 22:47 ` [PATCH v3 bpf-next 2/3] bpf: sync kernel uapi headers Javier Honduvilla Coto
2019-03-05 22:47 ` [PATCH v3 bpf-next 3/3] bpf: add tests for bpf_progenyof Javier Honduvilla Coto
2019-03-07 9:26 ` [PATCH v3 bpf-next 0/3] bpf: add bpf_progenyof helper Daniel Borkmann
2019-03-22 22:42 ` Javier Honduvilla Coto
2019-03-22 22:38 ` [PATCH v4 " Javier Honduvilla Coto
2019-03-22 22:38 ` [PATCH v4 bpf-next 1/3] " Javier Honduvilla Coto
2019-03-25 14:17 ` Daniel Borkmann
2019-03-27 15:57 ` Javier Honduvilla Coto
2019-03-27 20:44 ` Brendan Gregg
2019-03-27 16:02 ` Javier Honduvilla Coto [this message]
2019-03-22 22:38 ` [PATCH v4 bpf-next 2/3] bpf: sync kernel uapi headers Javier Honduvilla Coto
2019-03-22 22:38 ` [PATCH v4 bpf-next 3/3] bpf: add tests for bpf_progenyof Javier Honduvilla Coto
2019-04-10 20:36 ` [PATCH v5 bpf-next 0/3] bpf: add bpf_descendant_of helper Javier Honduvilla Coto
2019-04-10 20:36 ` [PATCH v5 bpf-next 1/3] " Javier Honduvilla Coto
2019-04-11 21:55 ` Daniel Borkmann
2019-04-12 0:20 ` Javier Honduvilla Coto
2019-04-10 20:36 ` [PATCH v5 bpf-next 2/3] bpf: sync kernel uapi headers Javier Honduvilla Coto
2019-04-10 20:36 ` [PATCH v5 bpf-next 3/3] bpf: add tests for bpf_descendant_of Javier Honduvilla Coto
2019-04-11 17:59 ` [PATCH v5 bpf-next 0/3] bpf: add bpf_descendant_of helper Song Liu
2019-07-10 18:00 ` [PATCH v6 " Javier Honduvilla Coto
2019-07-10 18:00 ` [PATCH v6 bpf-next 1/3] " Javier Honduvilla Coto
2019-07-10 18:00 ` [PATCH v6 bpf-next 2/3] bpf: sync kernel uapi headers Javier Honduvilla Coto
2019-07-10 18:00 ` [PATCH v6 bpf-next 3/3] bpf: add tests for bpf_descendant_of Javier Honduvilla Coto
2019-07-10 19:25 ` Andrii Nakryiko
2019-07-12 12:41 ` [PATCH v6 bpf-next 0/3] bpf: add bpf_descendant_of helper Daniel Borkmann
2019-03-01 18:06 ` [PATCH v2 bpf-next 2/3] bpf: sync kernel uapi headers Javier Honduvilla Coto
2019-03-01 18:06 ` [PATCH v2 bpf-next 3/3] bpf: add tests for bpf_progenyof Javier Honduvilla Coto
2019-02-26 22:36 ` [PATCH bpf-next 2/3] bpf: sync kernel uapi headers Javier Honduvilla Coto
2019-02-26 22:36 ` [PATCH bpf-next 3/3] bpf: add tests for bpf_progenyof Javier Honduvilla Coto
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190327160227.GB63993@fb.com \
--to=javierhonduco@fb$(echo .)com \
--cc=Kernel-team@fb$(echo .)com \
--cc=daniel@iogearbox$(echo .)net \
--cc=netdev@vger$(echo .)kernel.org \
--cc=yhs@fb$(echo .)com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox