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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Jann Horn <jannh@google.com>
Cc: Kees Cook <keescook@chromium.org>,
	"Tobin C. Harding" <me@tobin.cc>,
	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>,
	"kernel-hardening@lists.openwall.com" 
	<kernel-hardening@lists.openwall.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	William Roberts <william.c.roberts@intel.com>,
	Chris Fries <cfries@google.com>,
	Dave Weinstein <olorin@google.com>
Subject: Re: [kernel-hardening] [RFC V2 4/6] lib: vsprintf: default kptr_restrict to the maximum value
Date: Wed, 4 Oct 2017 12:23:02 -0700	[thread overview]
Message-ID: <CA+55aFwqyAzMR6PRYxu90Q2sB_cJ5JcP3ELH-BUGi-m0ti=X1w@mail.gmail.com> (raw)
In-Reply-To: <CAG48ez3z=5pgpG2B=AEEB1q6NPuZ9=LXKcOd8PEer1GUSdgjKw@mail.gmail.com>

On Wed, Oct 4, 2017 at 12:13 PM, Jann Horn <jannh@google.com> wrote:
>
> Actually, /proc/kallsyms uses %pK, which hacks around this issue
> by checking for `euid != uid` in addition to the capability check - so this
> isn't exploitable through a typical setuid program.

Fair enough, you'd have to be a pretty broken suid program to have set
uid to euid before reading some untrusted file descriptor.

I could still imagine happening (hey, the X server used to sendmsg
file descriptors back and forth), but hopefully it's not really
realistic.

                  Linus

  reply	other threads:[~2017-10-04 19:23 UTC|newest]

Thread overview: 80+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-01  0:06 [kernel-hardening] [RFC V2 0/6] add more kernel pointer filter options Tobin C. Harding
2017-10-01  0:06 ` [kernel-hardening] [RFC V2 1/6] lib: vsprintf: additional kernel pointer filtering options Tobin C. Harding
2017-10-04  8:55   ` Greg KH
2017-10-04 13:08     ` Steven Rostedt
2017-10-04 13:26       ` Greg KH
2017-10-04 13:29         ` Steven Rostedt
2017-10-04 13:54           ` Greg KH
2017-10-01  0:06 ` [kernel-hardening] [RFC V2 2/6] lib: vsprintf: whitelist stack traces Tobin C. Harding
2017-10-02 10:42   ` Will Deacon
2017-10-02 21:49     ` Tobin C. Harding
2017-10-04  8:56     ` Greg KH
2017-10-04  8:58       ` Will Deacon
2017-10-04  9:02         ` Greg KH
2017-10-04 10:42           ` Tobin C. Harding
2017-10-01  0:06 ` [kernel-hardening] [RFC V2 3/6] lib: vsprintf: physical address kernel pointer filtering options Tobin C. Harding
2017-10-04  8:58   ` Greg KH
2017-10-01  0:06 ` [kernel-hardening] [RFC V2 4/6] lib: vsprintf: default kptr_restrict to the maximum value Tobin C. Harding
2017-10-04  8:55   ` Greg KH
2017-10-04 16:42   ` Kees Cook
2017-10-04 16:42     ` Kees Cook
2017-10-04 16:48     ` Roberts, William C
2017-10-04 16:48       ` Roberts, William C
2017-10-04 17:08     ` Linus Torvalds
2017-10-04 17:08       ` Linus Torvalds
2017-10-04 17:28       ` Linus Torvalds
2017-10-04 17:28         ` Linus Torvalds
2017-10-04 19:13         ` Jann Horn
2017-10-04 19:13           ` Jann Horn
2017-10-04 19:23           ` Linus Torvalds [this message]
2017-10-04 19:23             ` Linus Torvalds
2017-10-01  0:06 ` [kernel-hardening] [RFC V2 5/6] lib: vsprintf: add "%paP", "%papP", and "%padP" specifiers Tobin C. Harding
2017-10-04  8:58   ` Greg KH
2017-10-01  0:06 ` [kernel-hardening] [RFC V2 6/6] drivers: uio: un-restrict sysfs pointers for UIO Tobin C. Harding
2017-10-04  8:58   ` Greg KH
2017-10-01  0:11 ` [kernel-hardening] [RFC V2 0/6] add more kernel pointer filter options Tobin C. Harding
2017-10-04  8:57   ` Greg KH
2017-10-04 10:45     ` Tobin C. Harding
2017-10-04  8:58 ` Greg KH
2017-10-04 10:50   ` Tobin C. Harding
2017-10-04 12:42     ` Greg KH
2017-10-04 13:28       ` Steven Rostedt
2017-10-04 13:28         ` Steven Rostedt
2017-10-04 13:31         ` Steven Rostedt
2017-10-04 16:17   ` Roberts, William C
2017-10-04 16:17     ` Roberts, William C
2017-10-04 15:41 ` Linus Torvalds
2017-10-04 15:41   ` Linus Torvalds
2017-10-04 16:22   ` Boris Lukashev
2017-10-04 16:22     ` Boris Lukashev
2017-10-04 16:29     ` Linus Torvalds
2017-10-04 16:29       ` Linus Torvalds
2017-10-04 16:54       ` Steven Rostedt
2017-10-04 16:54         ` Steven Rostedt
2017-10-04 18:58   ` Jordan Glover
2017-10-04 19:19     ` Linus Torvalds
2017-10-04 21:58       ` Roberts, William C
2017-10-04 23:21         ` Daniel Micay
2017-10-04 23:52         ` Linus Torvalds
2017-10-05  0:09           ` Linus Torvalds
2017-10-05 13:55             ` Bjorn Helgaas
2017-10-05  0:29           ` Daniel Micay
2017-10-05  0:35             ` Kees Cook
2017-10-06  8:33               ` Djalal Harouni
2017-10-05  2:19           ` Tobin C. Harding
2017-10-05  3:10             ` Linus Torvalds
2017-10-05  3:15               ` Kees Cook
2017-10-05 15:12               ` Roberts, William C
2017-10-05 16:19                 ` Linus Torvalds
2017-10-05 17:10                   ` Dave Weinstein
2017-10-07 23:44                   ` Theodore Ts'o
2017-10-08  0:08                     ` Linus Torvalds
2017-10-13 16:32                       ` Roberts, William C
2017-10-13 18:11                         ` Linus Torvalds
2017-10-13 19:34                           ` Kees Cook
2017-10-13 20:22                             ` Linus Torvalds
2017-10-13 20:47                               ` Kees Cook
2017-10-13 21:45                                 ` Linus Torvalds
2017-10-13 22:48                                 ` Theodore Ts'o
2017-10-13 16:14             ` Roberts, William C
2017-10-04 16:32 ` Ian Campbell

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