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Re: [musl] Re: [RFC] Possible new execveat(2) Linux syscall
- From: Christoph Hellwig <hch at infradead dot org>
- To: Rich Felker <dalias at aerifal dot cx>
- Cc: David Drysdale <drysdale at google dot com>, Andy Lutomirski <luto at amacapital dot net>, libc-alpha <libc-alpha at sourceware dot org>, musl at lists dot openwall dot com, Andrew Morton <akpm at linux-foundation dot org>, Linux API <linux-api at vger dot kernel dot org>, Christoph Hellwig <hch at infradead dot org>
- Date: Fri, 21 Nov 2014 02:10:15 -0800
- Subject: Re: [musl] Re: [RFC] Possible new execveat(2) Linux syscall
- Authentication-results: sourceware.org; auth=none
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On Mon, Nov 17, 2014 at 01:30:10PM -0500, Rich Felker wrote:
> On Mon, Nov 17, 2014 at 03:42:15PM +0000, David Drysdale wrote:
> > I'm not familiar with O_EXEC either, I'm afraid, so to be clear -- does
> > O_EXEC mean the permission check is explicitly skipped later, at execute
> > time? In other words, if you open(O_EXEC) an executable then remove the
> > execute bit from the file, does a subsequent fexecve() still work?
> Yes. It's just like how read and write permissions work. If you open a
> file for read then remove read permissions, or open it for write then
> remove write permissions, the existing permissions to the open file
> are not lost. Of course open with O_EXEC/O_SEARCH needs to fail if the
> caller does not have +x access to the file/directory at the time of
Adding a FMODE_EXEC similar to FMODE_READ/WRITE would be trivial.