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Groups > linux.kernel > #1637511
| From | Kees Cook <keescook@chromium.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode |
| Date | 2017-05-08 17:30 +0200 |
| Message-ID | <tESLM-5F6-25@gated-at.bofh.it> (permalink) |
| References | <tBg9X-Qc-7@gated-at.bofh.it> <tDTJT-7Nn-3@gated-at.bofh.it> <tELqV-VP-1@gated-at.bofh.it> <tEQJY-4ot-27@gated-at.bofh.it> <tERwm-4V1-7@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Mon, May 8, 2017 at 7:02 AM, Ingo Molnar <mingo@kernel.org> wrote: > > * Kees Cook <keescook@chromium.org> wrote: > >> > And yes, I realize that there were other such bugs and that such bugs might >> > occur in the future - but why not push the overhead of the security check to >> > the kernel build phase? I.e. I'm wondering how well we could do static >> > analysis during kernel build - would a limited mode of Sparse be good enough >> > for that? Or we could add a new static checker to tools/, built from first >> > principles and used primarily for extended syntactical checking. >> >> Static analysis is just not going to cover all cases. We've had vulnerabilities >> where interrupt handlers left KERNEL_DS set, for example. [...] > > Got any commit ID of that bug - was it because a function executed by the > interrupt handler leaked KERNEL_DS? Ah, it was an exception handler, but the one I was thinking of was this: https://lwn.net/Articles/419141/ >> [...] If there are performance concerns, let's put this behind a CONFIG. 2-5 >> instructions is not an issue for most people that want this coverage. > > That doesn't really _solve_ the performance concerns, it just forces most people > to enable it by creating a 'security or performance' false dichotomy ... That's fair, but what I'm trying to say is that many people will want this, so rejecting it because it's 2 more instructions seems unreasonable. We have had much more invasive changes added to the kernel. >> [...] and it still won't catch everything. Bug-finding is different from making >> a bug class just unexploitable at all. As we've done before, it's the difference >> between trying to find format string attacks vs just removing %n from the format >> parser. > > No, it does not make it unexploitable, it could still be exploitable if the > runtime check is buggy or if there's kernel execution outside of the regular > system call paths - there's plenty of such hardware functionality on x86 for > example. Fine, but this is splitting hairs. This does protect a specific situation, and it does so very cheaply. The real fix would be to remove set_fs() entirely. :P -Kees -- Kees Cook Pixel Security
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[PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Thomas Garnier <thgarnie@google.com> - 2017-04-28 17:40 +0200
Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Thomas Garnier <thgarnie@google.com> - 2017-05-06 00:20 +0200
Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Ingo Molnar <mingo@kernel.org> - 2017-05-08 09:40 +0200
Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Ingo Molnar <mingo@kernel.org> - 2017-05-08 10:00 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Daniel Micay <danielmicay@gmail.com> - 2017-05-08 17:30 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Kees Cook <keescook@chromium.org> - 2017-05-08 17:30 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Thomas Garnier <thgarnie@google.com> - 2017-05-08 22:00 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Ingo Molnar <mingo@kernel.org> - 2017-05-09 09:00 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Greg KH <greg@kroah.com> - 2017-05-09 13:20 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Thomas Garnier <thgarnie@google.com> - 2017-05-09 16:40 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Kees Cook <keescook@chromium.org> - 2017-05-09 18:40 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Greg KH <greg@kroah.com> - 2017-05-08 14:50 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Ingo Molnar <mingo@kernel.org> - 2017-05-09 08:50 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Christoph Hellwig <hch@infradead.org> - 2017-05-09 11:00 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Andy Lutomirski <luto@kernel.org> - 2017-05-09 15:10 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Christoph Hellwig <hch@infradead.org> - 2017-05-09 15:10 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Christoph Hellwig <hch@infradead.org> - 2017-05-09 18:10 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Kees Cook <keescook@chromium.org> - 2017-05-09 19:00 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Andy Lutomirski <luto@amacapital.net> - 2017-05-10 01:00 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Kees Cook <keescook@chromium.org> - 2017-05-10 01:40 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Andy Lutomirski <luto@kernel.org> - 2017-05-10 04:10 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Christoph Hellwig <hch@infradead.org> - 2017-05-10 09:20 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Borislav Petkov <bp@alien8.de> - 2017-05-11 13:30 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Christoph Hellwig <hch@infradead.org> - 2017-05-10 08:50 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-10 04:20 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-10 04:50 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-10 05:20 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-10 05:30 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-10 05:50 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Christoph Hellwig <hch@infradead.org> - 2017-05-10 09:00 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Christoph Hellwig <hch@infradead.org> - 2017-05-10 09:00 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-10 09:30 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Christoph Hellwig <hch@infradead.org> - 2017-05-10 09:40 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Christoph Hellwig <hch@infradead.org> - 2017-05-10 09:00 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Arnd Bergmann <arnd@arndb.de> - 2017-05-10 09:30 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Christoph Hellwig <hch@infradead.org> - 2017-05-10 09:40 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Brian Gerst <brgerst@gmail.com> - 2017-05-09 18:10 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Arnd Bergmann <arnd@arndb.de> - 2017-05-10 09:40 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-10 10:10 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Christoph Hellwig <hch@infradead.org> - 2017-05-10 10:20 +0200
Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Andy Lutomirski <luto@kernel.org> - 2017-05-11 02:20 +0200
Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Kees Cook <keescook@chromium.org> - 2017-05-08 15:20 +0200
Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Jann Horn <jannh@google.com> - 2017-05-08 16:10 +0200
Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-08 22:50 +0200
Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Ingo Molnar <mingo@kernel.org> - 2017-05-08 16:10 +0200
Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Kees Cook <keescook@chromium.org> - 2017-05-08 17:30 +0200
Re: [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Ingo Molnar <mingo@kernel.org> - 2017-05-09 08:40 +0200
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