From: Yonghong Song <yhs@fb.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>,
Carlos Neira <cneirabustos@gmail.com>
Cc: Networking <netdev@vger.kernel.org>,
"ebiederm@xmission.com" <ebiederm@xmission.com>,
Jesper Dangaard Brouer <brouer@redhat.com>,
bpf <bpf@vger.kernel.org>
Subject: Re: [PATCH bpf-next v11 2/4] bpf: added new helper bpf_get_ns_current_pid_tgid
Date: Fri, 27 Sep 2019 16:59:37 +0000 [thread overview]
Message-ID: <12db0313-668e-3825-d5fa-28d0f675808c@fb.com> (raw)
In-Reply-To: <CAEf4BzZeO3cZJWVG0min98gnFs3E8D1m67E+3A_9-rTjHA_Ybg@mail.gmail.com>
On 9/27/19 9:15 AM, Andrii Nakryiko wrote:
> On Thu, Sep 26, 2019 at 1:15 AM Carlos Neira <cneirabustos@gmail.com> wrote:
>>
>> New bpf helper bpf_get_ns_current_pid_tgid,
>> This helper will return pid and tgid from current task
>> which namespace matches dev_t and inode number provided,
>> this will allows us to instrument a process inside a container.
>>
>> Signed-off-by: Carlos Neira <cneirabustos@gmail.com>
>> ---
>> include/linux/bpf.h | 1 +
>> include/uapi/linux/bpf.h | 18 +++++++++++++++++-
>> kernel/bpf/core.c | 1 +
>> kernel/bpf/helpers.c | 32 ++++++++++++++++++++++++++++++++
>> kernel/trace/bpf_trace.c | 2 ++
>> 5 files changed, 53 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
>> index 5b9d22338606..231001475504 100644
>> --- a/include/linux/bpf.h
>> +++ b/include/linux/bpf.h
>> @@ -1055,6 +1055,7 @@ extern const struct bpf_func_proto bpf_get_local_storage_proto;
>> extern const struct bpf_func_proto bpf_strtol_proto;
>> extern const struct bpf_func_proto bpf_strtoul_proto;
>> extern const struct bpf_func_proto bpf_tcp_sock_proto;
>> +extern const struct bpf_func_proto bpf_get_ns_current_pid_tgid_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 77c6be96d676..9272dc8fb08c 100644
>> --- a/include/uapi/linux/bpf.h
>> +++ b/include/uapi/linux/bpf.h
>> @@ -2750,6 +2750,21 @@ union bpf_attr {
>> * **-EOPNOTSUPP** kernel configuration does not enable SYN cookies
>> *
>> * **-EPROTONOSUPPORT** IP packet version is not 4 or 6
>> + *
>> + * int bpf_get_ns_current_pid_tgid(u32 dev, u64 inum)
>> + * Return
>> + * A 64-bit integer containing the current tgid and pid from current task
>
> Function signature doesn't correspond to the actual return type (int vs u64).
>
>> + * which namespace inode and dev_t matches , and is create as such:
>> + * *current_task*\ **->tgid << 32 \|**
>> + * *current_task*\ **->pid**.
>> + *
>> + * On failure, the returned value is one of the following:
>> + *
>> + * **-EINVAL** if dev and inum supplied don't match dev_t and inode number
>> + * with nsfs of current task.
>> + *
>> + * **-ENOENT** if /proc/self/ns does not exists.
>> + *
>> */
>
> [...]
>
>> #include "../../lib/kstrtox.h"
>>
>> @@ -487,3 +489,33 @@ const struct bpf_func_proto bpf_strtoul_proto = {
>> .arg4_type = ARG_PTR_TO_LONG,
>> };
>> #endif
>> +
>> +BPF_CALL_2(bpf_get_ns_current_pid_tgid, u32, dev, u64, inum)
>
> Just curious, is dev_t officially specified as u32 and is never
> supposed to grow bigger? I wonder if accepting u64 might be more
> future-proof API here?
This is what we have now in kernel (include/linux/types.h)
typedef u32 __kernel_dev_t;
typedef __kernel_dev_t dev_t;
But userspace dev_t (defined at /usr/include/sys/types.h) have
8 bytes.
Agree. Let us just use u64. It won't hurt and also will be fine
if kernel internal dev_t becomes 64bit.
>
>> +{
>> + struct task_struct *task = current;
>> + struct pid_namespace *pidns;
>
> [...]
>
next prev parent reply other threads:[~2019-09-27 16:59 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-24 15:20 [PATCH V11 0/4] BPF: New helper to obtain namespace data from current task Carlos Neira
2019-09-24 15:20 ` [PATCH bpf-next v11 1/4] fs/nsfs.c: added ns_match Carlos Neira
2019-09-24 15:20 ` [PATCH bpf-next v11 2/4] bpf: added new helper bpf_get_ns_current_pid_tgid Carlos Neira
2019-09-27 16:15 ` Andrii Nakryiko
2019-09-27 16:59 ` Yonghong Song [this message]
2019-09-27 17:24 ` Andrii Nakryiko
2019-09-28 1:42 ` Carlos Antonio Neira Bustos
2019-09-24 15:20 ` [PATCH bpf-next v11 3/4] tools: Added bpf_get_ns_current_pid_tgid helper Carlos Neira
2019-09-25 3:27 ` Yonghong Song
2019-09-24 15:20 ` [PATCH bpf-next v11 4/4] tools/testing/selftests/bpf: Add self-tests for new helper Carlos Neira
2019-09-25 16:07 ` Yonghong Song
2019-09-25 20:33 ` Carlos Antonio Neira Bustos
2019-09-24 18:01 ` [PATCH V11 0/4] BPF: New helper to obtain namespace data from current task Daniel Borkmann
2019-09-24 18:14 ` Carlos Antonio Neira Bustos
2019-09-26 0:59 ` Eric W. Biederman
2019-09-26 15:51 ` Yonghong Song
2019-09-26 16:16 ` John Fastabend
2019-09-26 17:01 ` Yonghong Song
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