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Open Source and information security mailing list archives
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Date: Tue, 27 Oct 2009 09:11:41 +0100 From: Pavel Machek <pavel@....cz> To: Trond Myklebust <trond.myklebust@....uio.no> Cc: Jan Kara <jack@...e.cz>, "J. Bruce Fields" <bfields@...ldses.org>, "Serge E. Hallyn" <serue@...ibm.com>, kernel list <linux-kernel@...r.kernel.org>, linux-fsdevel@...r.kernel.org, viro@...iv.linux.org.uk, jamie@...reable.org Subject: Re: symlinks with permissions On Mon 2009-10-26 14:22:16, Trond Myklebust wrote: > On Sun, 2009-10-25 at 10:36 +0100, Pavel Machek wrote: > > Well, it is unexpected and mild security hole. > > > > Part of the problem is that even if you have read-only > > filedescriptor, you can upgrade it to read-write, even if path is > > inaccessible to you. > > > > So if someone passes you read-only filedescriptor, you can still write > > to it. > > If someone passes you a file descriptor, can't you in any case play > games with, openat(fd,"",O_RDWR), in order to achieve the same thing? I > must admit I haven't tried it yet, but at a first glance I can't see > anything that prevents me from doing this... According to my documentation, openat needs directory fd. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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