From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "Tobin C. Harding" <me@tobin.cc>,
kernel-hardening@lists.openwall.com,
"Jason A. Donenfeld" <Jason@zx2c4.com>,
Theodore Ts'o <tytso@mit.edu>,
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>, Joe Perches <joe@perches.com>,
Ian Campbell <ijc@hellion.org.uk>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <wil.deacon@arm.com>, Chris Fries <cfries@google.com>,
Dave Weinstein <olorin@google.com>,
Daniel Micay <danielmicay@gmail.com>,
Djalal Harouni <tixxdz@gmail.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
David Miller <davem@davemloft.net>,
Network Development <netdev@vger.kernel.org>,
linux-kernel@vger.kernel.org
Subject: [kernel-hardening] Re: [PATCH] kallsyms: don't leak address when printing symbol
Date: Thu, 9 Nov 2017 13:23:18 +0900 [thread overview]
Message-ID: <20171109042318.GB775@jagdpanzerIV> (raw)
In-Reply-To: <20171108223555.52c01531@vmware.local.home>
On (11/08/17 22:35), Steven Rostedt wrote:
> On Thu, 9 Nov 2017 12:50:29 +1100
> "Tobin C. Harding" <me@tobin.cc> wrote:
>
> > Currently if a pointer is printed using %p[ssB] and the symbol is not
> > found (kallsyms_lookup() fails) then we print the actual address. This
> > leaks kernel addresses. We should instead print something _safe_.
> >
> > Print "<no-symbol>" instead of kernel address.
>
> Ug, ftrace requires this to work as is, as it uses it to print some
> addresses that may or may not be a symbol.
>
> If anything, can this return a success or failure if it were to find a
> symbol or not, and then something like ftrace could decide to use %x if
> it does not.
>
> And yes, ftrace leaks kernel addresses all over the place, that's just
> the nature of tracing the kernel.
>
agree, I kinda suspect that that "0x%lx" sometimes can be useful.
at least one can tell if the frame is from modules or kernel, and
objdump it may be.
-ss
WARNING: multiple messages have this Message-ID (diff)
From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "Tobin C. Harding" <me@tobin.cc>,
kernel-hardening@lists.openwall.com,
"Jason A. Donenfeld" <Jason@zx2c4.com>,
"Theodore Ts'o" <tytso@mit.edu>,
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>, Joe Perches <joe@perches.com>,
Ian Campbell <ijc@hellion.org.uk>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <wil.deacon@arm.com>, Chris Fries <cfries@google.com>,
Dave Weinstein <olorin@google.com>,
Daniel Micay <danielmicay@gmail.com>,
Djalal Harouni <tixxdz@gmail.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
David Miller <davem@davemloft.net>,
Network Development <netdev@vger.kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kallsyms: don't leak address when printing symbol
Date: Thu, 9 Nov 2017 13:23:18 +0900 [thread overview]
Message-ID: <20171109042318.GB775@jagdpanzerIV> (raw)
In-Reply-To: <20171108223555.52c01531@vmware.local.home>
On (11/08/17 22:35), Steven Rostedt wrote:
> On Thu, 9 Nov 2017 12:50:29 +1100
> "Tobin C. Harding" <me@tobin.cc> wrote:
>
> > Currently if a pointer is printed using %p[ssB] and the symbol is not
> > found (kallsyms_lookup() fails) then we print the actual address. This
> > leaks kernel addresses. We should instead print something _safe_.
> >
> > Print "<no-symbol>" instead of kernel address.
>
> Ug, ftrace requires this to work as is, as it uses it to print some
> addresses that may or may not be a symbol.
>
> If anything, can this return a success or failure if it were to find a
> symbol or not, and then something like ftrace could decide to use %x if
> it does not.
>
> And yes, ftrace leaks kernel addresses all over the place, that's just
> the nature of tracing the kernel.
>
agree, I kinda suspect that that "0x%lx" sometimes can be useful.
at least one can tell if the frame is from modules or kernel, and
objdump it may be.
-ss
WARNING: multiple messages have this Message-ID (diff)
From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "Tobin C. Harding" <me@tobin.cc>,
kernel-hardening@lists.openwall.com,
"Jason A. Donenfeld" <Jason@zx2c4.com>,
Theodore Ts'o <tytso@mit.edu>,
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>, Joe Perches <joe@perches.com>,
Ian Campbell <ijc@hellion.org.uk>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <wil.deacon@arm.com>, Chris Fries <cfries@google.com>,
Dave Weinstein <olorin@google.co
Subject: Re: [PATCH] kallsyms: don't leak address when printing symbol
Date: Thu, 9 Nov 2017 13:23:18 +0900 [thread overview]
Message-ID: <20171109042318.GB775@jagdpanzerIV> (raw)
In-Reply-To: <20171108223555.52c01531@vmware.local.home>
On (11/08/17 22:35), Steven Rostedt wrote:
> On Thu, 9 Nov 2017 12:50:29 +1100
> "Tobin C. Harding" <me@tobin.cc> wrote:
>
> > Currently if a pointer is printed using %p[ssB] and the symbol is not
> > found (kallsyms_lookup() fails) then we print the actual address. This
> > leaks kernel addresses. We should instead print something _safe_.
> >
> > Print "<no-symbol>" instead of kernel address.
>
> Ug, ftrace requires this to work as is, as it uses it to print some
> addresses that may or may not be a symbol.
>
> If anything, can this return a success or failure if it were to find a
> symbol or not, and then something like ftrace could decide to use %x if
> it does not.
>
> And yes, ftrace leaks kernel addresses all over the place, that's just
> the nature of tracing the kernel.
>
agree, I kinda suspect that that "0x%lx" sometimes can be useful.
at least one can tell if the frame is from modules or kernel, and
objdump it may be.
-ss
next prev parent reply other threads:[~2017-11-09 4:23 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-09 1:50 [kernel-hardening] [PATCH] kallsyms: don't leak address when printing symbol Tobin C. Harding
2017-11-09 1:50 ` Tobin C. Harding
2017-11-09 1:50 ` Tobin C. Harding
2017-11-09 3:35 ` [kernel-hardening] " Steven Rostedt
2017-11-09 3:35 ` Steven Rostedt
2017-11-09 3:35 ` Steven Rostedt
2017-11-09 4:23 ` Sergey Senozhatsky [this message]
2017-11-09 4:23 ` Sergey Senozhatsky
2017-11-09 4:23 ` Sergey Senozhatsky
2017-11-09 5:45 ` [kernel-hardening] " Tobin C. Harding
2017-11-09 5:45 ` Tobin C. Harding
2017-11-09 5:45 ` Tobin C. Harding
2017-11-09 18:15 ` [kernel-hardening] " Steven Rostedt
2017-11-09 18:15 ` Steven Rostedt
2017-11-09 18:15 ` Steven Rostedt
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