From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [RFC] Possible new execveat(2) Linux syscall Date: Fri, 21 Nov 2014 02:13:18 -0800 Message-ID: <20141121101318.GG8866@infradead.org> References: <20141116195246.GX22465@brightrain.aerifal.cx> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Content-Disposition: inline In-Reply-To: <20141116195246.GX22465@brightrain.aerifal.cx> To: Rich Felker Cc: David Drysdale , libc-alpha@sourceware.org, Andrew Morton , Christoph Hellwig , Linux API , Andy Lutomirski , musl@lists.openwall.com List-Id: linux-api@vger.kernel.org On Sun, Nov 16, 2014 at 02:52:46PM -0500, Rich Felker wrote: > I've been following the discussions so far and everything looks mostly > okay. There are still issues to be resolved with the different > semantics between Linux O_PATH and what POSIX requires for O_EXEC (and > O_SEARCH) but as long as the intent is that, once O_EXEC is defined to > save the permissions at the time of open and cause them to be used in > place of the current file permissions at the time of execveat As far as I can tell we only need the little patch below to make Linux O_PATH a valid O_SEARCH implementation. Rich, you said you wanted to look over it? For O_EXEC my interpretation is that we basically just need this new execveat syscall + a patch to add FMODE_EXEC and enforce it. So we wouldn't even need the O_PATH|3 hack. But unless someone more familar with the arcane details of the Posix language verifies it I'm tempted to give up trying to help to implent these flags :( diff --git a/fs/open.c b/fs/open.c index d6fd3ac..ee24720 100644 --- a/fs/open.c +++ b/fs/open.c @@ -512,7 +512,7 @@ out_unlock: SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode) { - struct fd f = fdget(fd); + struct fd f = fdget_raw(fd); int err = -EBADF; if (f.file) { @@ -633,7 +633,7 @@ SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group) { - struct fd f = fdget(fd); + struct fd f = fdget_raw(fd); int error = -EBADF; if (!f.file)