From: Joe Perches <joe@perches.com>
To: "Tobin C. Harding" <me@tobin.cc>,
kernel-hardening@lists.openwall.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: 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: Tue, 10 Oct 2017 21:06:50 -0700 [thread overview]
Message-ID: <1507694810.3552.45.camel@perches.com> (raw)
In-Reply-To: <1507693696-3777-1-git-send-email-me@tobin.cc>
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;
}
WARNING: multiple messages have this Message-ID (diff)
From: Joe Perches <joe@perches.com>
To: "Tobin C. Harding" <me@tobin.cc>,
kernel-hardening@lists.openwall.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: 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: Tue, 10 Oct 2017 21:06:50 -0700 [thread overview]
Message-ID: <1507694810.3552.45.camel@perches.com> (raw)
In-Reply-To: <1507693696-3777-1-git-send-email-me@tobin.cc>
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;
}
next prev parent reply other threads:[~2017-10-11 4:06 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 ` Joe Perches [this message]
2017-10-11 4:06 ` Joe Perches
2017-10-12 2:24 ` [kernel-hardening] " Tobin C. Harding
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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