Bug#862461: tiptop: requires root to run

[Gunnar Wolf]

tags 862461 + patch
thanks

I agree with Nathaniel, the currently displayed message is too
confusing for regular users. A proper message should be displayed,
even if it means a (small!) deviation from upstream.

I am attaching a patch here, please consider!
Description: Report that root access is required
 When perf_event_paranoid level is set to 3 (default), tiptop requires
 root access to be run (#862461). Notify the user accordingly.
Author: Gunnar Wolf 

Origin: vendor https://bugs.debian.org/862461
Bug-Debian: https://bugs.debian.org/862461
Forwarded: no
Reviewed-By: Gunnar Wolf 
Last-Update: 2017-10-31

Index: tiptop-2.3.1/src/requisite.c
===
--- tiptop-2.3.1.orig/src/requisite.c
+++ tiptop-2.3.1/src/requisite.c
@@ -69,8 +69,11 @@ int check()
 else if (strcmp(os.release, "2.6.31") < 0) {  /* lexicographic order */
   fprintf(stderr, "Linux 2.6.31+ is required, OS reports '%s'.\n",
   os.release);
-}
-else {
+} else if (paranoia_level == 3) {
+  fprintf(stderr, "Your kernel is set with an event paranoia value of 3\n");
+  fprintf(stderr, "Either run this program as root, or set a lower\n");
+  fprintf(stderr, "paranoia value at '%s'.\n", PARANOID2);
+} else {
   fprintf(stderr, "Don't know why...\n");
 }
 exit(EXIT_FAILURE);


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Bug#862461: tiptop: requires root to run

[Nathaniel Beaver]

Dear Thomasz and Ben,

Many thanks for the explanation. I can confirm that the workaround is 
effective. (In hindsight the man page has somewhat documented this 
behavior under the ``--kernel'' flag.)


The only thing I have to add is that an edit to this part of the man 
page may be in order:



Unless tiptop is run by root, or the executable is setuid-root, a user can only 
monitor the tasks it owns.


I don't think adding the workaround to the man page is necessary, but it 
would be good to know that by default tiptop requires root to monitor 
any tasks at all.


Also, if upstream is amenable, a more specific error message would be great.

Cheers,

Nathaniel

On 05/15/2017 01:35 AM, Tomasz Buchert wrote:

On 14/05/17 20:58, Ben Hutchings wrote:

On Sun, 2017-05-14 at 10:43 +0200, Tomasz Buchert wrote:

On 12/05/17 18:54, Nathaniel Beaver wrote:

[...]


Thank you, Nathaniel.

I confirm the problem. A safe bet is that
https://lkml.org/lkml/2016/1/11/587 is the cause.  You can verify that
/proc/sys/kernel/perf_event_paranoid contains "3". By running

echo 2 | sudo tee /proc/sys/kernel/perf_event_paranoid

you should be able to use tiptop as a normal user again.

I doubt that we can switch the default value in Debian kernels to "2",
so I have to say that simply the tiptop website is not up-to-date, at
least with respect to the Debian kernels (but also likely to other
distributions as well). I'm CCing Ben to let him comment on this.


The Debian kernel default is not going to be changed in the short term.
 In the long term it's conceivable that performance events will
eventually become sufficiently robust that it would be reasonable to
change the default.

Ben.

--
Ben Hutchings - Debian developer, member of kernel, installer and LTS teams


Thank you!

Nathaniel, I'll keep this bug open till possibly the perf events will
become available for normal users. Till then I require you to use the
workaround above if you feel like it.

Cheers,
Tomasz

Bug#862461: tiptop: requires root to run

[Tomasz Buchert]

On 14/05/17 20:58, Ben Hutchings wrote:
> On Sun, 2017-05-14 at 10:43 +0200, Tomasz Buchert wrote:
> > On 12/05/17 18:54, Nathaniel Beaver wrote:
> > > [...]
> >
> > Thank you, Nathaniel.
> >
> > I confirm the problem. A safe bet is that
> > https://lkml.org/lkml/2016/1/11/587 is the cause.  You can verify that
> > /proc/sys/kernel/perf_event_paranoid contains "3". By running
> >
> > echo 2 | sudo tee /proc/sys/kernel/perf_event_paranoid
> >
> > you should be able to use tiptop as a normal user again.
> >
> > I doubt that we can switch the default value in Debian kernels to "2",
> > so I have to say that simply the tiptop website is not up-to-date, at
> > least with respect to the Debian kernels (but also likely to other
> > distributions as well). I'm CCing Ben to let him comment on this.
>
> The Debian kernel default is not going to be changed in the short term.
>  In the long term it's conceivable that performance events will
> eventually become sufficiently robust that it would be reasonable to
> change the default.
>
> Ben.
>
> --
> Ben Hutchings - Debian developer, member of kernel, installer and LTS teams

Thank you!

Nathaniel, I'll keep this bug open till possibly the perf events will
become available for normal users. Till then I require you to use the
workaround above if you feel like it.

Cheers,
Tomasz


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Description: PGP signature

Bug#862461: tiptop: requires root to run

[Ben Hutchings]

On Sun, 2017-05-14 at 10:43 +0200, Tomasz Buchert wrote:
> On 12/05/17 18:54, Nathaniel Beaver wrote:
> > [...]
> 
> Thank you, Nathaniel.
> 
> I confirm the problem. A safe bet is that
> https://lkml.org/lkml/2016/1/11/587 is the cause.  You can verify that
> /proc/sys/kernel/perf_event_paranoid contains "3". By running
> 
> echo 2 | sudo tee /proc/sys/kernel/perf_event_paranoid
> 
> you should be able to use tiptop as a normal user again.
> 
> I doubt that we can switch the default value in Debian kernels to "2",
> so I have to say that simply the tiptop website is not up-to-date, at
> least with respect to the Debian kernels (but also likely to other
> distributions as well). I'm CCing Ben to let him comment on this.

The Debian kernel default is not going to be changed in the short term.
 In the long term it's conceivable that performance events will
eventually become sufficiently robust that it would be reasonable to
change the default.

Ben.

-- 
Ben Hutchings - Debian developer, member of kernel, installer and LTS teams

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Description: This is a digitally signed message part

Bug#862461: tiptop: requires root to run

[Tomasz Buchert]

On 12/05/17 18:54, Nathaniel Beaver wrote:
> [...]

Thank you, Nathaniel.

I confirm the problem. A safe bet is that
https://lkml.org/lkml/2016/1/11/587 is the cause.  You can verify that
/proc/sys/kernel/perf_event_paranoid contains "3". By running

echo 2 | sudo tee /proc/sys/kernel/perf_event_paranoid

you should be able to use tiptop as a normal user again.

I doubt that we can switch the default value in Debian kernels to "2",
so I have to say that simply the tiptop website is not up-to-date, at
least with respect to the Debian kernels (but also likely to other
distributions as well). I'm CCing Ben to let him comment on this.

Cheers,
Tomasz


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Description: PGP signature

Bug#862461: tiptop: requires root to run

[Nathaniel Beaver]

Package: tiptop
Version: 2.2-2
Severity: important

Dear Maintainer,

Running tiptop results in a return status of 1 and this on stderr:


syscall: Operation not permitted
Could not perform syscall.
Don't know why...


It runs as expected as root or using sudo.

The homepage for tiptop lists "No root privilege needed" as a feature, 
so this is not expected behavior.


Sincerely,

Nathaniel Beaver

-- System Information:
Debian Release: 8.8
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.8.0-0.bpo.2-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8) (ignored: 
LC_ALL set to en_US.UTF-8)

Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages tiptop depends on:
ii  libc62.19-18+deb8u9
ii  libncurses5  5.9+20140913-1+b1
ii  libtinfo55.9+20140913-1+b1
ii  libxml2  2.9.1+dfsg1-5+deb8u4

tiptop recommends no packages.

tiptop suggests no packages.

-- no debconf information