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From: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
To: Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>
Cc: "Christoph Hellwig" <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
	"Andy Lutomirski" <luto-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	"Mark Rutland" <mark.rutland-5wv7dgnIgG8@public.gmane.org>,
	"Kernel Hardening"
	<kernel-hardening-ZwoEplunGu1jrUoiu81ncdBPR1lH4CV8@public.gmane.org>,
	"Greg KH" <greg-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>,
	"Heiko Carstens"
	<heiko.carstens-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>,
	LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	"David Howells"
	<dhowells-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	"Dave Hansen"
	<dave.hansen-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	"H . Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>,
	"Ingo Molnar" <mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	"Pavel Tikhomirov"
	<ptikhomirov-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>,
	"Peter Zijlstra"
	<a.p.zijlstra-/NLkJaSkS4VmR6Xm/wNWPw@public.gmane.org>,
	linux-s390 <linux-s390-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	"the arch/x86 maintainers"
	<x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	"Russell King" <linux-I+IVW8TIWO2tmTQ+vhA3Yw@public.gmane.org>,
	"Will Deacon" <will.deacon-5wv7dgnIgG8@public.gmane.org>,
	"Christian Borntraeger"
	<borntraeger-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>,
	"René Nyffenegger" <mail@renenyffene>
Subject: Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode
Date: Tue, 9 May 2017 16:31:00 -0700	[thread overview]
Message-ID: <CAGXu5jL6PeQmmdxh5h--fgrMK8DW_XZYpNfDOvvv_o9E3-Kxdw@mail.gmail.com> (raw)
In-Reply-To: <CALCETrV73=cDvaSLOMvb299yaGNJYME8LC-=P+N6p7R1NN97Yg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

On Tue, May 9, 2017 at 3:52 PM, Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org> wrote:
> On Tue, May 9, 2017 at 9:50 AM, Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org> wrote:
>> On Tue, May 9, 2017 at 9:03 AM, Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org> wrote:
>>> On Tue, May 09, 2017 at 06:02:50AM -0700, Christoph Hellwig wrote:
>>>> On Tue, May 09, 2017 at 06:00:01AM -0700, Andy Lutomirski wrote:
>>>> > fs/splice.c has some, ahem, interesting uses that have been the source
>>>> > of nasty exploits in the past.  Converting them to use iov_iter
>>>> > properly would be really, really nice.  Christoph, I don't suppose
>>>> > you'd like to do that?
>>>>
>>>> I can take care of all the fs code including this one.
>>>
>>> I spent the afternoon hacking up where I'd like this to head.  It's
>>> completely untested as of now:
>>>
>>>         http://git.infradead.org/users/hch/vfs.git/shortlog/refs/heads/setfs-elimination
>>
>> Ooooh yes! Nice work.
>>
>> I love this:
>> http://git.infradead.org/users/hch/vfs.git/commitdiff/51e83f50f824ca23f5584c172138e6b7c2ff786d
>> but I wonder what it'll cause out-of-tree code to do. I mean, I'd
>> rather nothing out-of-tree be calling these, but I'd hate 3rd party
>> hacks even more.
>>
>> http://git.infradead.org/users/hch/vfs.git/commitdiff/018e0e9030777121fe87e89d43066691e7366587
>> This accidentally(?) removes the kernel-doc comments.
>>
>> http://git.infradead.org/users/hch/vfs.git/commitdiff/78b62c730254fc39fa888cdbdca08fde6e09a798
>> Could this be made defensive? (Return 0 if ret wraps, for example?) I
>> see what the comment says, but not everyone will read that. :(
>>
>> http://git.infradead.org/users/hch/vfs.git/commitdiff/a106276ca0294be054bc89ce97219933fe543df1
>> Perhaps unconditionally set USER_DS on exit instead of retaining
>> whatever was there?
>
> I don't like silent fixups.  If we want to do this, we should BUG or
> at least WARN, not just change the addr limit.  But I'm also not
> convinced it's indicative of an actual bug here.

Nothing should enter that function with KERNEL_DS set, right?

BUG_ON(get_fs() != USER_DS);
set_fs(KERNEL_DS);
...
set_fs(USER_DS);

-Kees

-- 
Kees Cook
Pixel Security

  parent reply	other threads:[~2017-05-09 23:31 UTC|newest]

Thread overview: 89+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-28 15:32 [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Thomas Garnier
     [not found] ` <20170428153213.137279-1-thgarnie-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2017-04-28 15:32   ` [PATCH v9 2/4] x86/syscalls: Optimize address limit check Thomas Garnier
2017-05-05 22:18   ` [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Thomas Garnier
     [not found]     ` <CAJcbSZGQsRVg3QZ9QfLn2HBC+RP-7fUTab0bYDJ455d8y8GyNw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-08  7:33       ` Ingo Molnar
     [not found]         ` <20170508073352.caqe3fqf7nuxypgi-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-05-08  7:52           ` Ingo Molnar
     [not found]             ` <20170508075209.7aluvpwildw325rf-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-05-08 15:22               ` [kernel-hardening] " Daniel Micay
2017-05-08 15:26                 ` Kees Cook
2017-05-08 19:51                   ` Thomas Garnier
     [not found]                   ` <CAGXu5jL61K0bRSEg9a_LswNyrt3K1J57REbWVcvAXT54zWwtMA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-09  6:56                     ` Ingo Molnar
     [not found]                       ` <20170509065619.wmqa6z6w3n6xpvrw-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-05-09 11:10                         ` Greg KH
     [not found]                           ` <20170509111007.GA14702-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2017-05-09 14:29                             ` Thomas Garnier
     [not found]                               ` <CAJcbSZFswDWZoK-1UK+xkRMJ4ttSYbtH2Y5WD5_aPR-8ru6t8A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-11 23:17                                 ` Thomas Garnier
     [not found]                                   ` <CAJcbSZEoRyewUtBHvqmNZL9FtT_q42Vmmd-EuC50x-ZRASiHHg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-11 23:44                                     ` Linus Torvalds
     [not found]                                       ` <CA+55aFwvQfs_X+paQF6Luc0Rq+W3J2fKuHRou7=ANcquDdXdDA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-12  5:28                                         ` Martin Schwidefsky
2017-05-12  5:34                                           ` Kees Cook
2017-05-12  5:54                                             ` Martin Schwidefsky
2017-05-12 19:01                                               ` Kees Cook
2017-05-12 19:08                                                 ` Russell King - ARM Linux
     [not found]                                                 ` <CAGXu5jL9vUrn4kpjO+qa4cHmWBypeqP17OGbrMs=5Nz0YpQMZw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-12 19:08                                                   ` Linus Torvalds
     [not found]                                                     ` <CA+55aFzbiBqsYb7vwO=+L4Vp_GOgPu+DBOrq4fBnyzq5DbBehg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-12 19:30                                                       ` Kees Cook
     [not found]                                                         ` <CAGXu5j+xmyJ6RhtPw9rUgs7k3sZ1KKWffvyGGG--oPfu9W42ng-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-12 20:21                                                           ` Russell King - ARM Linux
2017-05-12 20:30                                                             ` Peter Zijlstra
     [not found]                                                               ` <20170512203044.GI4626-IIpfhp3q70z/8w/KjCw3T+5/BudmfyzbbVWyRVo5IupeoWH0uzbU5w@public.gmane.org>
2017-05-12 20:45                                                                 ` Russell King - ARM Linux
2017-05-12 21:00                                                                   ` Kees Cook
     [not found]                                                                     ` <CAGXu5jL6FPuShBpZfi6+XHqOk4gxocUJRYPHT5oR3HYh3xm+sA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-12 21:04                                                                       ` Kees Cook
2017-05-13  7:21                                                               ` Christoph Hellwig
2017-05-12 21:06                                                             ` Al Viro
     [not found]                                                               ` <20170512210645.GS390-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2017-05-12 21:16                                                                 ` [kernel-hardening] " Daniel Micay
2017-05-12 21:17                                                                 ` Kees Cook
     [not found]                                                                   ` <CAGXu5jJu=VTqp2tzkPB4RAVxdGC+_SSQwrUwdzWpu24AA-zEcg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-12 21:23                                                                     ` Daniel Micay
2017-05-12 21:41                                                                     ` Al Viro
2017-05-12 21:47                                                                       ` Rik van Riel
     [not found]                                                                         ` <1494625675.29205.21.camel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2017-05-12 22:57                                                                           ` Al Viro
     [not found]                                                                       ` <20170512214144.GT390-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2017-05-12 21:50                                                                         ` Kees Cook
     [not found]                                             ` <CAGXu5j+EatK=DYONRkgovwLgytAnbG8jnAZaMSLckZFNVj3gig-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-12  6:57                                               ` Ingo Molnar
2017-05-12  6:13                                       ` Andy Lutomirski
2017-05-12  6:58                                       ` Ingo Molnar
2017-05-12 17:05                                         ` Thomas Garnier
2017-05-09 16:30                       ` [kernel-hardening] " Kees Cook
2017-05-08 12:46           ` Greg KH
     [not found]             ` <20170508124621.GA20705-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2017-05-09  6:45               ` Ingo Molnar
     [not found]                 ` <20170509064522.anusoikaalvlux3w-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-05-09  8:56                   ` Christoph Hellwig
2017-05-09 13:00                     ` Andy Lutomirski
2017-05-09 13:02                       ` [kernel-hardening] " Christoph Hellwig
2017-05-09 16:03                         ` Christoph Hellwig
2017-05-09 16:50                           ` Kees Cook
     [not found]                             ` <CAGXu5jKHVMRMKDfn+=kkbm+JkWPhoEtDwKx=QXAYxg1p9bn7PQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-09 22:52                               ` Andy Lutomirski
     [not found]                                 ` <CALCETrV73=cDvaSLOMvb299yaGNJYME8LC-=P+N6p7R1NN97Yg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-09 23:31                                   ` Kees Cook [this message]
2017-05-10  1:59                                     ` Andy Lutomirski
2017-05-10  7:15                                     ` Christoph Hellwig
     [not found]                                     ` <CAGXu5jL6PeQmmdxh5h--fgrMK8DW_XZYpNfDOvvv_o9E3-Kxdw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-11 11:22                                       ` Borislav Petkov
2017-05-10  6:46                             ` Christoph Hellwig
     [not found]                           ` <20170509160322.GA15902-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2017-05-10  2:11                             ` Al Viro
2017-05-10  2:45                               ` Al Viro
2017-05-10  3:12                                 ` Al Viro
     [not found]                                   ` <20170510031254.GC390-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2017-05-10  3:21                                     ` Al Viro
     [not found]                                       ` <20170510032137.GD390-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2017-05-10  3:39                                         ` Al Viro
2017-05-10  6:54                                           ` Christoph Hellwig
2017-05-10  6:53                                   ` Christoph Hellwig
2017-05-10  7:27                                     ` Al Viro
2017-05-10  7:35                                       ` Christoph Hellwig
2017-05-10  6:49                                 ` Christoph Hellwig
2017-05-10  7:28                             ` Arnd Bergmann
2017-05-10  7:35                               ` Christoph Hellwig
2017-05-09 16:05                       ` Brian Gerst
     [not found]                       ` <CALCETrUh8NO2scaqEM48K70Fo2+V3=Cpyk4JurCDiCYp4nm_+g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-10  7:37                         ` [kernel-hardening] " Arnd Bergmann
2017-05-10  8:08                           ` Al Viro
2017-05-10  8:14                             ` Christoph Hellwig
2017-05-11  0:18                               ` Andy Lutomirski
2017-05-12  7:00                         ` Ingo Molnar
2017-05-12  7:15                           ` Al Viro
2017-05-12  7:35                             ` Christoph Hellwig
2017-05-12  8:07                               ` Christoph Hellwig
2017-05-12  8:23                                 ` Greg KH
     [not found]                             ` <20170512071549.GP390-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2017-05-12  7:43                               ` [kernel-hardening] " Arnd Bergmann
2017-05-12  8:11                                 ` Christoph Hellwig
2017-05-12  8:16                                   ` Al Viro
2017-05-12  8:11                                 ` Al Viro
     [not found]                                   ` <20170512081154.GQ390-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2017-05-12  8:20                                     ` Arnd Bergmann
2017-05-12 23:20                               ` Andy Lutomirski
2017-05-08 13:09         ` Kees Cook
2017-05-08 14:02           ` Ingo Molnar
     [not found]             ` <20170508140230.23kxf2kfeazeo4zr-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-05-08 14:06               ` Jann Horn
     [not found]                 ` <CAG48ez0Hz=CimkPwuq903tgJkGj8gXUtiQJJb-P2zUes6bd6Hw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-08 20:48                   ` Al Viro
     [not found]                     ` <20170508204858.GT29622-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2017-05-12 23:15                       ` Andy Lutomirski
2017-05-08 15:24               ` Kees Cook
     [not found]                 ` <CAGXu5jJ4iY7QZ9wRu5dmm7RHtLh_V6TQh4huWwLCYPKOr63aiA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-09  6:34                   ` Ingo Molnar
2017-04-28 15:32 ` [PATCH v9 3/4] arm/syscalls: Optimize address limit check Thomas Garnier
2017-04-28 15:32 ` [PATCH v9 4/4] arm64/syscalls: " Thomas Garnier

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