Re: Correct way to include siginfo.h?

[Kees Cook]

On Tue, Mar 27, 2012 at 10:37 AM, Ted Ts'o <tytso@xxxxxxx> wrote:
> On Tue, Mar 27, 2012 at 10:29:39AM -0700, Kees Cook wrote:
>>
>> I'm trying to get at the future seccomp fields on siginfo_t, namely
>> "si_syscall":
>
> Ah, I didn't realize you were trying to do that.  siginfo_t has been
> stable since forever, and so I think we've always depending on glibc
> to export the structure.  As a result I don't know that much effort
> has been made to make siginfo.h safe for any userspace user other than
> glibc.
>
> Silly question; we're not going to actually change the size of the
> siginfo_t structure in a userspace visible way, are we?  I don't know
> of are any shared libraries that fill in a siginfo_t structure passed
> in by the caller (which could be located on the stack), but it's
> certainly possible that such library ABI's could exist.

No, siginfo, IIUC, is defined to be SI_MAX_SIZE bytes. The union for
seccomp (on SIGSYS) just uses a long and 2 ints. It'd be nice for
there to be a stable way to get the kernel's siginfo instead of
glibc's.

-Kees

-- 
Kees Cook
Chrome OS Security
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