linux-kernel - Re: [patch 3/4 v2] vfs: utimensat(): fix error checking for {UTIME_NOW,UTIME

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Date:	Wed, 04 Jun 2008 16:50:59 +0200
From:	Michael Kerrisk <mtk.manpages@...glemail.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	lkml <linux-kernel@...r.kernel.org>,
	Christoph Hellwig <hch@....de>,
	Miklos Szeredi <miklos@...redi.hu>, viro@...iv.linux.org.uk,
	jamie@...reable.org, Ulrich Drepper <drepper@...hat.com>,
	linux-fsdevel@...r.kernel.org,
	Subrata Modak <subrata@...ux.vnet.ibm.com>
Subject: Re: [patch 3/4 v2] vfs: utimensat(): fix error checking for {UTIME_NOW,UTIME_OMIT}
 case

Andrew,

This patch improves the indentation of the previous patch.
(No other changes).

Cheers,

Michael

--- linux-2.6.26-rc4/fs/utimes.c	2008-06-04 13:36:33.000000000 +0200
+++ linux-2.6.26-rc4-utimensat-fix-v4/fs/utimes.c	2008-06-04 13:35:14.000000000 +0200
@@ -40,14 +40,9 @@

 #endif

-static bool nsec_special(long nsec)
-{
-	return nsec == UTIME_OMIT || nsec == UTIME_NOW;
-}
-
 static bool nsec_valid(long nsec)
 {
-	if (nsec_special(nsec))
+	if (nsec == UTIME_OMIT || nsec == UTIME_NOW)
 		return true;

 	return nsec >= 0 && nsec <= 999999999;
@@ -106,7 +101,7 @@
 		     times[1].tv_nsec == UTIME_NOW)
 		times = NULL;

-	/* Don't worry, the checks are done in inode_change_ok() */
+	/* In most cases, the checks are done in inode_change_ok() */
 	newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
 	if (times) {
 		error = -EPERM;
@@ -128,15 +123,26 @@
 			newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
 			newattrs.ia_valid |= ATTR_MTIME_SET;
 		}
-	}

-	/*
-	 * If times is NULL or both times are either UTIME_OMIT or
-	 * UTIME_NOW, then need to check permissions, because
-	 * inode_change_ok() won't do it.
-	 */
-	if (!times || (nsec_special(times[0].tv_nsec) &&
-		       nsec_special(times[1].tv_nsec))) {
+		/*
+		 * For the UTIME_OMIT/UTIME_NOW and UTIME_NOW/UTIME_OMIT
+		 * cases, we need to make an extra check that is not done by
+		 * inode_change_ok().
+		 */
+		if (((times[0].tv_nsec == UTIME_NOW &&
+			    times[1].tv_nsec == UTIME_OMIT)
+		     ||
+		     (times[0].tv_nsec == UTIME_OMIT &&
+			    times[1].tv_nsec == UTIME_NOW))
+		    && !is_owner_or_cap(inode))
+			goto mnt_drop_write_and_out;
+	} else {
+
+		/*
+		 * If times is NULL (or both times are UTIME_NOW),
+		 * then we need to check permissions, because
+		 * inode_change_ok() won't do it.
+		 */
 		error = -EACCES;
                 if (IS_IMMUTABLE(inode))
 			goto mnt_drop_write_and_out;


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