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From: "Tobin C. Harding" <me@tobin.cc>
To: Joe Perches <joe@perches.com>
Cc: kernel-hardening@lists.openwall.com, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Kees Cook <keescook@chromium.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Tycho Andersen <tycho@docker.com>,
	"Roberts, William C" <william.c.roberts@intel.com>,
	Tejun Heo <tj@kernel.org>,
	Jordan Glover <Golden_Miller83@protonmail.ch>,
	Greg KH <gregkh@linuxfoundation.org>,
	Petr Mladek <pmladek@suse.com>, Ian Campbell <ijc@hellion.org.uk>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Chris Fries <cfries@google.com>,
	Dave Weinstein <olorin@google.com>,
	Daniel Micay <danielmicay@gmail.com>,
	Djalal Harouni <tixxdz@gmail.com>
Subject: [kernel-hardening] Re: [PATCH] printk: hash addresses printed with %p
Date: Thu, 12 Oct 2017 13:24:08 +1100	[thread overview]
Message-ID: <20171012022408.GC30753@eros> (raw)
In-Reply-To: <1507694810.3552.45.camel@perches.com>

On Tue, Oct 10, 2017 at 09:06:50PM -0700, Joe Perches wrote:
> On Wed, 2017-10-11 at 14:48 +1100, Tobin C. Harding wrote:
> > Currently there are many places in the kernel where addresses are being
> > printed using an unadorned %p. Kernel pointers should be printed using
> > %pK allowing some control via the kptr_restrict sysctl. Exposing addresses
> > gives attackers sensitive information about the kernel layout in memory.
> []
> > diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> []
> > @@ -1591,6 +1591,35 @@ char *device_node_string(char *buf, char *end, struct device_node *dn,
> >  	return widen_string(buf, buf - buf_start, end, spec);
> >  }
> >  
> > +static long get_random_odd_long(void)
> > +{
> > +	long val = 0;
> > +
> > +	while((val & 1) == 0) {
> > +		val = get_random_long();
> > +	}
> > +
> > +	return val;
> > +}
> 
> Perhaps
> 
> static long get_random_odd_long(void)
> {
> 	return get_random_long() | 1L;
> }
> 

Nice.

thanks,
Tobin.

WARNING: multiple messages have this Message-ID (diff)
From: "Tobin C. Harding" <me@tobin.cc>
To: Joe Perches <joe@perches.com>
Cc: kernel-hardening@lists.openwall.com, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Kees Cook <keescook@chromium.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Tycho Andersen <tycho@docker.com>,
	"Roberts, William C" <william.c.roberts@intel.com>,
	Tejun Heo <tj@kernel.org>,
	Jordan Glover <Golden_Miller83@protonmail.ch>,
	Greg KH <gregkh@linuxfoundation.org>,
	Petr Mladek <pmladek@suse.com>, Ian Campbell <ijc@hellion.org.uk>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Chris Fries <cfries@google.com>,
	Dave Weinstein <olorin@google.com>,
	Daniel Micay <danielmicay@gmail.com>,
Subject: Re: [PATCH] printk: hash addresses printed with %p
Date: Thu, 12 Oct 2017 13:24:08 +1100	[thread overview]
Message-ID: <20171012022408.GC30753@eros> (raw)
In-Reply-To: <1507694810.3552.45.camel@perches.com>

On Tue, Oct 10, 2017 at 09:06:50PM -0700, Joe Perches wrote:
> On Wed, 2017-10-11 at 14:48 +1100, Tobin C. Harding wrote:
> > Currently there are many places in the kernel where addresses are being
> > printed using an unadorned %p. Kernel pointers should be printed using
> > %pK allowing some control via the kptr_restrict sysctl. Exposing addresses
> > gives attackers sensitive information about the kernel layout in memory.
> []
> > diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> []
> > @@ -1591,6 +1591,35 @@ char *device_node_string(char *buf, char *end, struct device_node *dn,
> >  	return widen_string(buf, buf - buf_start, end, spec);
> >  }
> >  
> > +static long get_random_odd_long(void)
> > +{
> > +	long val = 0;
> > +
> > +	while((val & 1) == 0) {
> > +		val = get_random_long();
> > +	}
> > +
> > +	return val;
> > +}
> 
> Perhaps
> 
> static long get_random_odd_long(void)
> {
> 	return get_random_long() | 1L;
> }
> 

Nice.

thanks,
Tobin.

WARNING: multiple messages have this Message-ID (diff)
From: "Tobin C. Harding" <me@tobin.cc>
To: Joe Perches <joe@perches.com>
Cc: kernel-hardening@lists.openwall.com, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Kees Cook <keescook@chromium.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Tycho Andersen <tycho@docker.com>,
	"Roberts, William C" <william.c.roberts@intel.com>,
	Tejun Heo <tj@kernel.org>,
	Jordan Glover <Golden_Miller83@protonmail.ch>,
	Greg KH <gregkh@linuxfoundation.org>,
	Petr Mladek <pmladek@suse.com>, Ian Campbell <ijc@hellion.org.uk>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Chris Fries <cfries@google.com>,
	Dave Weinstein <olorin@google.com>,
	Daniel Micay <danielmicay@gmail.com>,
	Djalal Harouni <tixxdz@gmail.com>
Subject: Re: [PATCH] printk: hash addresses printed with %p
Date: Thu, 12 Oct 2017 13:24:08 +1100	[thread overview]
Message-ID: <20171012022408.GC30753@eros> (raw)
In-Reply-To: <1507694810.3552.45.camel@perches.com>

On Tue, Oct 10, 2017 at 09:06:50PM -0700, Joe Perches wrote:
> On Wed, 2017-10-11 at 14:48 +1100, Tobin C. Harding wrote:
> > Currently there are many places in the kernel where addresses are being
> > printed using an unadorned %p. Kernel pointers should be printed using
> > %pK allowing some control via the kptr_restrict sysctl. Exposing addresses
> > gives attackers sensitive information about the kernel layout in memory.
> []
> > diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> []
> > @@ -1591,6 +1591,35 @@ char *device_node_string(char *buf, char *end, struct device_node *dn,
> >  	return widen_string(buf, buf - buf_start, end, spec);
> >  }
> >  
> > +static long get_random_odd_long(void)
> > +{
> > +	long val = 0;
> > +
> > +	while((val & 1) == 0) {
> > +		val = get_random_long();
> > +	}
> > +
> > +	return val;
> > +}
> 
> Perhaps
> 
> static long get_random_odd_long(void)
> {
> 	return get_random_long() | 1L;
> }
> 

Nice.

thanks,
Tobin.

  reply	other threads:[~2017-10-12  2:24 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-11  3:48 [kernel-hardening] [PATCH] printk: hash addresses printed with %p Tobin C. Harding
2017-10-11  3:48 ` Tobin C. Harding
2017-10-11  3:48 ` Tobin C. Harding
2017-10-11  4:06 ` [kernel-hardening] " Joe Perches
2017-10-11  4:06   ` Joe Perches
2017-10-12  2:24   ` Tobin C. Harding [this message]
2017-10-12  2:24     ` Tobin C. Harding
2017-10-12  2:24     ` Tobin C. Harding
2017-10-11 16:49 ` [kernel-hardening] " Linus Torvalds
2017-10-11 16:49   ` Linus Torvalds
2017-10-11 16:49   ` Linus Torvalds
2017-10-11 17:48 ` [kernel-hardening] " Theodore Ts'o
2017-10-11 17:48   ` Theodore Ts'o
2017-10-12  2:55   ` [kernel-hardening] " Tobin C. Harding

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