Re: [resend][PATCH v9 2/3] /proc/PID/status: show all sets of pid according to ns

Re: [resend][PATCH v9 2/3] /proc/PID/status: show all sets of pid according to ns

[Nathan Scott]

Hi Chen, Eric,

Eric W. Biederman <ebiederm@xmission.com> writes:
> Chen Hanxiao <chenhanxiao@cn.fujitsu.com> writes:
> > If some issues occurred inside a container guest, host user
> > could not know which process is in trouble just by guest pid:
> > [...]
> > Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
> > Tested-by: Serge Hallyn <serge.hallyn@canonical.com>
> >
> > Signed-off-by: Chen Hanxiao <chenhanxiao@cn.fujitsu.com>
> 
> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
> 
> At a quick review and read through this looks good.  Once I finish
> clearing the security bug fixes from my tree I will see about picking
> this up.

I recently came across a need for this patch so I just wanted to
say thanks and since I've used it a fair bit feel free to add:

Tested-by: Nathan Scott <nathans@redhat.com>

One small tweak you could make is to drop the extra whitespace
from those new seq_printf calls - "\t%d " has a trailing space
that isn't needed.

Also there's proc status docs below Documentation/ that should be
updated for these changes.  They are slightly out-of-date already
and there's a few typos in the vicinity - something like this may
do the trick though ... ?  (will need to be updated at merge time
with the correct kernel version)


docs: add missing and new /proc/PID/status file entries, fix typos

Signed-off-by: Nathan Scott <nathans@redhat.com>

diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index aae9dd1..457cebd 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -197,12 +197,12 @@ contains details information about the process itself.  Its fields are
 explained in Table 1-4.
 
 (for SMP CONFIG users)
-For making accounting scalable, RSS related information are handled in
-asynchronous manner and the vaule may not be very precise. To see a precise
+For making accounting scalable, RSS related information are handled in an
+asynchronous manner and the value may not be very precise. To see a precise
 snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table.
 It's slow but very precise.
 
-Table 1-2: Contents of the status files (as of 2.6.30-rc7)
+Table 1-2: Contents of the status files (as of 3.20.0)
 ..............................................................................
  Field                       Content
  Name                        filename of the executable
@@ -210,6 +210,7 @@ Table 1-2: Contents of the status files (as of 2.6.30-rc7)
                              in an uninterruptible wait, Z is zombie,
 			     T is traced or stopped)
  Tgid                        thread group ID
+ Ngid                        NUMA group ID (0 if none)
  Pid                         process id
  PPid                        process id of the parent process
  TracerPid                   PID of process tracing this process (0 if not)
@@ -217,6 +218,10 @@ Table 1-2: Contents of the status files (as of 2.6.30-rc7)
  Gid                         Real, effective, saved set, and  file system GIDs
  FDSize                      number of file descriptor slots currently allocated
  Groups                      supplementary group list
+ NStgid                      descendant namespace thread group ID hierarchy
+ NSpid                       descendant namespace process ID hierarchy
+ NSpgid                      descendant namespace process group ID hierarchy
+ NSsid                       descendant namespace session ID hierarchy
  VmPeak                      peak virtual memory size
  VmSize                      total program size
  VmLck                       locked memory size

[resend][PATCH v9 0/3] ns, procfs: pid conversion between ns and showing pidns hierarchy

[Chen Hanxiao]

This series will expose pid inside containers
via procfs.
Also show the hierarchy of pid namespcae.
Then we could know how pid looks inside a container
and their ns relationships.

1. helpful for nested container checkpoint/restore

  We could know whether two pids had relationship
  between each other.

      init_pid_ns 1
            │
   ┌────────────┐
  ns1                       ns2
   │                        │
  200                       300
                             │
                            ns2
                             │
                            400

  #cat /proc/pidns_hierarchy
  200 1 1
  300 1 1
  400 300 2

2. useful for pid translation from container
  Ex:
       init_pid_ns    ns1         ns2
   t1  2
   t2   `- 3          1
   t3   `- 4          3
   t4       `- 5      `- 5        1
   t5       `- 6      `- 8        3

  It could solve problems like: we see a pid 3 goes wrong
  in container's log, what is its pid on hosts:
  a) inside container:
  # readlink /proc/3/ns/pid
  pid:[4026532388]

  b) on host:
  We show it in the form of :
  <init_PID> <parent_of_init_PID> <relative PID level>

  # cat /proc/pidns_hierarchy
  14918 1 1
  16263 14918 2
  16581 1 1
  Then we could easily find /proc/16263/ns/pid->4026532388.
  On host, we knew that reported pid 3 is in level 2,
   and its parental pid ns is from pid 14918.

  c) on host, check child of 16263, grep it from status:
  NSpid:  16268   8       3

  We knew that pid 16268 is pid 3 reported by container.

v9: fix codes be inluded if CONFIG_PID_NS=n
    add docs to describe the usage of pidns_hierarchy procfs
v8: fix some improper comments
    use max() from kernel.h
v7: change pidns_hierarchy style to be consistent
    with current interface like:
    <init_PID> <parent_of_init_PID> <relative PID level>
    remove EXPERT dependent in Kconfig.
v6: fix some get_pid leaks and do some cleanups.
v5: collect pid by find_ge_pid;
    use local list inside nslist_proc_show;
    use get_pid, remove mutex lock.
v4: simplify pid collection and some performance optimizamtion;
    fix another race issue.
v3: fix a race issue and memory leak issue in pidns_hierarchy;
    add another two fielsd: NSpgid and NSsid.
v2: use a procfs text file, replacing dirs under /proc for
    showing pidns hierarchy;
    add two new fields: NStgid and NSpid
    keep fields of Tgid and Pid unchanged for back compatibility.

Chen Hanxiao (3):
  procfs: show hierarchy of pid namespace
  /proc/PID/status: show all sets of pid according to ns
  Documentation: add docs for /proc/pidns_hierarchy

 Documentation/namespaces/pidns-hierarchy.txt |  51 +++++
 fs/proc/Kconfig                              |   6 +
 fs/proc/Makefile                             |   1 +
 fs/proc/array.c                              |  16 ++
 fs/proc/internal.h                           |   9 +
 fs/proc/pidns_hierarchy.c                    | 280 +++++++++++++++++++++++++++
 fs/proc/root.c                               |   1 +
 7 files changed, 364 insertions(+)
 create mode 100644 Documentation/namespaces/pidns-hierarchy.txt
 create mode 100644 fs/proc/pidns_hierarchy.c

-- 
1.9.3

[resend][PATCH v9 2/3] /proc/PID/status: show all sets of pid according to ns

[Chen Hanxiao]

If some issues occurred inside a container guest, host user
could not know which process is in trouble just by guest pid:
the users of container guest only knew the pid inside containers.
This will bring obstacle for trouble shooting.

This patch adds four fields: NStgid, NSpid, NSpgid and NSsid:
a) In init_pid_ns, nothing changed;

b) In one pidns, will tell the pid inside containers:
  NStgid: 21776   5       1
  NSpid:  21776   5       1
  NSpgid: 21776   5       1
  NSsid:  21729   1       0
  ** Process id is 21776 in level 0, 5 in level 1, 1 in level 2.

c) If pidns is nested, it depends on which pidns are you in.
  NStgid: 5       1
  NSpid:  5       1
  NSpgid: 5       1
  NSsid:  1       0
  ** Views from level 1

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Tested-by: Serge Hallyn <serge.hallyn@canonical.com>

Signed-off-by: Chen Hanxiao <chenhanxiao@cn.fujitsu.com>
---
v9: rebased on 3.19-rc1
No change from v4-v8
v3: add another two fielsd: NSpgid and NSsid.
v2: add two new fields: NStgid and NSpid.
    keep fields of Tgid and Pid unchanged for back compatibility.

 fs/proc/array.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/fs/proc/array.c b/fs/proc/array.c
index bd117d0..35205d4 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -208,6 +208,22 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
 			   from_kgid_munged(user_ns, GROUP_AT(group_info, g)));
 	put_cred(cred);
 
+	seq_puts(m, "\nNStgid:");
+	for (g = ns->level; g <= pid->level; g++)
+		seq_printf(m, "\t%d ",
+			task_tgid_nr_ns(p, pid->numbers[g].ns));
+	seq_puts(m, "\nNSpid:");
+	for (g = ns->level; g <= pid->level; g++)
+		seq_printf(m, "\t%d ",
+			task_pid_nr_ns(p, pid->numbers[g].ns));
+	seq_puts(m, "\nNSpgid:");
+	for (g = ns->level; g <= pid->level; g++)
+		seq_printf(m, "\t%d ",
+			task_pgrp_nr_ns(p, pid->numbers[g].ns));
+	seq_puts(m, "\nNSsid:");
+	for (g = ns->level; g <= pid->level; g++)
+		seq_printf(m, "\t%d ",
+			task_session_nr_ns(p, pid->numbers[g].ns));
 	seq_putc(m, '\n');
 }
 
-- 
1.9.3

Re: [resend][PATCH v9 2/3] /proc/PID/status: show all sets of pid according to ns

[Eric W. Biederman]

Chen Hanxiao <chenhanxiao@cn.fujitsu.com> writes:

> If some issues occurred inside a container guest, host user
> could not know which process is in trouble just by guest pid:
> the users of container guest only knew the pid inside containers.
> This will bring obstacle for trouble shooting.
>
> This patch adds four fields: NStgid, NSpid, NSpgid and NSsid:
> a) In init_pid_ns, nothing changed;
>
> b) In one pidns, will tell the pid inside containers:
>   NStgid: 21776   5       1
>   NSpid:  21776   5       1
>   NSpgid: 21776   5       1
>   NSsid:  21729   1       0
>   ** Process id is 21776 in level 0, 5 in level 1, 1 in level 2.
>
> c) If pidns is nested, it depends on which pidns are you in.
>   NStgid: 5       1
>   NSpid:  5       1
>   NSpgid: 5       1
>   NSsid:  1       0
>   ** Views from level 1
>
> Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
> Tested-by: Serge Hallyn <serge.hallyn@canonical.com>
>
> Signed-off-by: Chen Hanxiao <chenhanxiao@cn.fujitsu.com>

Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>

At a quick review and read through this looks good.  Once I finish
clearing the security bug fixes from my tree I will see about picking this
up.

Eric


> ---
> v9: rebased on 3.19-rc1
> No change from v4-v8
> v3: add another two fielsd: NSpgid and NSsid.
> v2: add two new fields: NStgid and NSpid.
>     keep fields of Tgid and Pid unchanged for back compatibility.
>
>  fs/proc/array.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/fs/proc/array.c b/fs/proc/array.c
> index bd117d0..35205d4 100644
> --- a/fs/proc/array.c
> +++ b/fs/proc/array.c
> @@ -208,6 +208,22 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
>  			   from_kgid_munged(user_ns, GROUP_AT(group_info, g)));
>  	put_cred(cred);
>  
> +	seq_puts(m, "\nNStgid:");
> +	for (g = ns->level; g <= pid->level; g++)
> +		seq_printf(m, "\t%d ",
> +			task_tgid_nr_ns(p, pid->numbers[g].ns));
> +	seq_puts(m, "\nNSpid:");
> +	for (g = ns->level; g <= pid->level; g++)
> +		seq_printf(m, "\t%d ",
> +			task_pid_nr_ns(p, pid->numbers[g].ns));
> +	seq_puts(m, "\nNSpgid:");
> +	for (g = ns->level; g <= pid->level; g++)
> +		seq_printf(m, "\t%d ",
> +			task_pgrp_nr_ns(p, pid->numbers[g].ns));
> +	seq_puts(m, "\nNSsid:");
> +	for (g = ns->level; g <= pid->level; g++)
> +		seq_printf(m, "\t%d ",
> +			task_session_nr_ns(p, pid->numbers[g].ns));
>  	seq_putc(m, '\n');
>  }