Date: Sat, 23 Feb 2013 00:01:39 -0500 From: KOSAKI Motohiro <kosaki.motohiro@...il.com> To: Rich Felker <dalias@...ifal.cx> Cc: libc-alpha <libc-alpha@...rceware.org>, musl@...ts.openwall.com Subject: Re: O_EXEC and O_SEARCH > 1. Try to open with O_RDONLY. If it succeeds, we're done. This is > REALLY nice because it means O_SEARCH and O_EXEC "just work" even on > ancient or broken kernels as long as the target file is readable. Hmm.. This algorithm seems slightly strange to me. Why do you want to try O_RDONLY at first? O_RDONLY require read permission and O_SEARCH, if i understand correctly, doesn't. I think you should try O_PATH at first. > > 2. Else, add O_PATH and try again. If it still fails, we have a > pre-2.6.39 kernel and there's nothing we can do, so just report > failure. > > 3. If open succeeds with O_PATH, then if O_NOFOLLOW is also specified, > check fstat, and close the file and report error if fstat succeeded > and the obtained fd was a symbolic link. > > 4. If fstat failed, we have a buggy kernel, so either close and report > an error, or just ignore the failure (possibly ignoring the > requirements of O_NOFOLLOW), as there seems to be no way to handle it > correctly on such kernels. > > If the kernel developers ever add O_SEARCH/O_EXEC at the kernel level > with our proposed value of 3, a step 0, just passing the value to the > kernel directly and seeing if it works, could also be added. > > Rich
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.