ALT Linux kernel packages development
 help / color / mirror / Atom feed
From: Andrey Savchenko <bircoph@altlinux.org>
To: ALT Linux kernel packages development <devel-kernel@lists.altlinux.org>
Subject: Re: [d-kernel] [PATCH] UBUNTU: SAUCE: security, perf: Allow further restriction of perf_event_open
Date: Thu, 2 Jun 2022 21:42:03 +0300
Message-ID: <20220602214203.3c68997e3f33b29be6adf2ea@altlinux.org> (raw)
In-Reply-To: <YpkA3DLcFOLzGd4A@portlab>

[-- Attachment #1: Type: text/plain, Size: 6188 bytes --]

On Thu, 2 Jun 2022 21:26:36 +0300 Vladimir D. Seleznev wrote:
> On Thu, Jun 02, 2022 at 06:58:41PM +0300, Andrey Savchenko wrote:
> > On Thu, 2 Jun 2022 15:40:38 +0300 Vitaly Chikunov wrote:
> > > Dmitry,
> > > 
> > > On Thu, Jun 02, 2022 at 10:14:38AM +0300, Dmitry V. Levin wrote:
> > > > On Thu, Jun 02, 2022 at 03:31:00AM +0300, Vitaly Chikunov wrote:
> > > > > From: Ben Hutchings <ben@decadent.org.uk>
> > > > > 
> > > > > https://lkml.org/lkml/2016/1/11/587
> > > > > 
> > > > > The GRKERNSEC_PERF_HARDEN feature extracted from grsecurity.  Adds the
> > > > > option to disable perf_event_open() entirely for unprivileged users.
> > > > > This standalone version doesn't include making the variable read-only
> > > > > (or renaming it).
> > > > > 
> > > > > When kernel.perf_event_open is set to 3 (or greater), disallow all
> > > > ----------------------------------------^
> > > > 
> > > > > access to performance events by users without CAP_SYS_ADMIN.
> > > > > Add a Kconfig symbol CONFIG_SECURITY_PERF_EVENTS_RESTRICT that
> > > > > makes this value the default.
> > > > > 
> > > > > This is based on a similar feature in grsecurity
> > > > > (CONFIG_GRKERNSEC_PERF_HARDEN).  This version doesn't include making
> > > > > the variable read-only.  It also allows enabling further restriction
> > > > > at run-time regardless of whether the default is changed.
> > > > > 
> > > > > Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
> > > > > Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
> > > > > [ saf: resolve conflicts with v5.8-rc1 ]
> > > > > Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
> > > > > [ vt: Make it default y. ]
> > > > > Signed-off-by: Vitaly Chikunov <vt@altlinux.org>
> > > > > ---
> > > > >  include/linux/perf_event.h |  6 ++++++
> > > > >  kernel/events/core.c       |  8 ++++++++
> > > > >  security/Kconfig           | 10 ++++++++++
> > > > >  3 files changed, 24 insertions(+)
> > > > > 
> > > > > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> > > > > index 733649184b27..b00607abbcdf 100644
> > > > > --- a/include/linux/perf_event.h
> > > > > +++ b/include/linux/perf_event.h
> > > > > @@ -1342,6 +1342,12 @@ int perf_event_max_stack_handler(struct ctl_table *table, int write,
> > > > >  #define PERF_SECURITY_CPU		1
> > > > >  #define PERF_SECURITY_KERNEL		2
> > > > >  #define PERF_SECURITY_TRACEPOINT	3
> > > > > +#define PERF_SECURITY_MAX		4
> > > > ----------------------------------------^
> > > > 
> > > > > +
> > > > > +static inline bool perf_paranoid_any(void)
> > > > > +{
> > > > > +	return sysctl_perf_event_paranoid >= PERF_SECURITY_MAX;
> > > > > +}
> > > > >  
> > > > >  static inline int perf_is_paranoid(void)
> > > > >  {
> > > > > diff --git a/kernel/events/core.c b/kernel/events/core.c
> > > > > index 2d7a23a7507b..15a3b37ae213 100644
> > > > > --- a/kernel/events/core.c
> > > > > +++ b/kernel/events/core.c
> > > > > @@ -414,8 +414,13 @@ static struct kmem_cache *perf_event_cache;
> > > > >   *   0 - disallow raw tracepoint access for unpriv
> > > > >   *   1 - disallow cpu events for unpriv
> > > > >   *   2 - disallow kernel profiling for unpriv
> > > > > + *   4 - disallow all unpriv perf event use
> > > > --------^
> > > > 
> > > > >   */
> > > > > +#ifdef CONFIG_SECURITY_PERF_EVENTS_RESTRICT
> > > > > +int sysctl_perf_event_paranoid __read_mostly = PERF_SECURITY_MAX;
> > > > > +#else
> > > > >  int sysctl_perf_event_paranoid __read_mostly = 2;
> > > > > +#endif
> > > > >  
> > > > >  /* Minimum for 512 kiB + 1 user control page */
> > > > >  int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024); /* 'free' kiB per user */
> > > > > @@ -12148,6 +12153,9 @@ SYSCALL_DEFINE5(perf_event_open,
> > > > >  	if (err)
> > > > >  		return err;
> > > > >  
> > > > > +	if (perf_paranoid_any() && !capable(CAP_SYS_ADMIN))
> > > > > +		return -EACCES;
> > > > > +
> > > > >  	err = perf_copy_attr(attr_uptr, &attr);
> > > > >  	if (err)
> > > > >  		return err;
> > > > > diff --git a/security/Kconfig b/security/Kconfig
> > > > > index 6c7b35c941c7..4861085a2d49 100644
> > > > > --- a/security/Kconfig
> > > > > +++ b/security/Kconfig
> > > > > @@ -19,6 +19,16 @@ config SECURITY_DMESG_RESTRICT
> > > > >  
> > > > >  	  If you are unsure how to answer this question, answer N.
> > > > >  
> > > > > +config SECURITY_PERF_EVENTS_RESTRICT
> > > > > +	bool "Restrict unprivileged use of performance events"
> > > > > +	depends on PERF_EVENTS
> > > > > +	default y
> > > > > +	help
> > > > > +	  If you say Y here, the kernel.perf_event_paranoid sysctl
> > > > > +	  will be set to 3 by default, and no unprivileged use of the
> > > > -------------------------^
> > > 
> > > Я это заметил, но, думаю, так надо и оставить.
> > 
> > Можно пояснить зачем? Какие задачи планируется этим решить?
> > Считается ли нормальным, что профилировать нужно будет под рутом?
> > Всё же хотелось бы, чтоб пользователь мог полноценно заниматься
> > разработкой и отладкой приложений.
> 
> Не сказать, что профилирование — типичная задача. Если есть потребность
> профилировать не из-под рута, то ничего не мешает переключить ручку на
> подходящее значение.

И сделать ребут, да?

А профилирование ведь не только разработчику нужно, но и админу,
особенно на высоконагруженных системах для поиска узких мест.

Т.е. в реальности всё будет от рута делаться и безопасность
промышленных систем и систем разработки будет деградирована.

Best regards,
Andrew Savchenko

[-- Attachment #2: Type: application/pgp-signature, Size: 833 bytes --]

  reply	other threads:[~2022-06-02 18:42 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-02  0:31 Vitaly Chikunov
2022-06-02  7:14 ` Dmitry V. Levin
2022-06-02 12:40   ` Vitaly Chikunov
2022-06-02 13:29     ` Vitaly Chikunov
2022-06-02 15:58     ` Andrey Savchenko
2022-06-02 17:06       ` Vitaly Chikunov
2022-06-02 18:26       ` Vladimir D. Seleznev
2022-06-02 18:42         ` Andrey Savchenko [this message]
2022-06-02 18:56           ` Dmitry V. Levin
2022-06-03  6:27             ` Andrey Savchenko
2022-06-02 19:08           ` Vladimir D. Seleznev
2022-06-03  6:16             ` Andrey Savchenko
2022-06-03 12:41               ` Vladimir D. Seleznev
2022-06-03 12:54                 ` Andrey Savchenko
2022-06-02 15:15 ` Alexey Sheplyakov
2022-06-02 16:39   ` Dmitry V. Levin
2022-06-03  6:25     ` Andrey Savchenko
2022-06-03 15:07       ` Vitaly Chikunov
2022-06-05  7:48     ` Alexey Sheplyakov
2022-06-05  7:59       ` Dmitry V. Levin
2022-06-06 14:31         ` Alexey Sheplyakov
2022-06-05 13:04       ` Vladimir D. Seleznev
2022-06-06  9:20         ` Alexey Sheplyakov
2022-06-06 10:31           ` Andrey Savchenko
2022-06-06 12:10             ` Alexey Sheplyakov
2022-06-06 12:53           ` Vladimir D. Seleznev
2022-06-06 12:59             ` Vladimir D. Seleznev
2022-06-08 14:27             ` [d-kernel] right to profile (Re: [PATCH] UBUNTU: SAUCE: security, perf: Allow further restriction of perf_event_open) Alexey Sheplyakov
2022-06-15 11:19               ` [d-kernel] [JT] Re: right to profile Michael Shigorin

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=20220602214203.3c68997e3f33b29be6adf2ea@altlinux.org \
    --to=bircoph@altlinux.org \
    --cc=devel-kernel@lists.altlinux.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

ALT Linux kernel packages development

This inbox may be cloned and mirrored by anyone:

	git clone --mirror http://lore.altlinux.org/devel-kernel/0 devel-kernel/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 devel-kernel devel-kernel/ http://lore.altlinux.org/devel-kernel \
		devel-kernel@altlinux.org devel-kernel@altlinux.ru devel-kernel@altlinux.com
	public-inbox-index devel-kernel

Example config snippet for mirrors.
Newsgroup available over NNTP:
	nntp://lore.altlinux.org/org.altlinux.lists.devel-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git