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From: Vitaly Chikunov <vt@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 15:40:38 +0300
Message-ID: <20220602124038.ov7aoh5qcbrvc4ei@altlinux.org> (raw)
In-Reply-To: <20220602071438.GA5852@altlinux.org>

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.

> 
> 
> -- 
> ldv
> _______________________________________________
> devel-kernel mailing list
> devel-kernel@lists.altlinux.org
> https://lists.altlinux.org/mailman/listinfo/devel-kernel


  reply	other threads:[~2022-06-02 12:40 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 [this message]
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
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

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