From: Miklos Szeredi <mszeredi@suse.cz>
Date: Mon, 31 Jan 2011 16:40:49 +0000 (+0100)
Subject: Always call mount with --no-canonicalize option
X-Git-Tag: fuse_2_8_6~4
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=e9ae66eb4e7af14e2cd27b90f88b599b61f96e8a;p=qemu-gpiodev%2Flibfuse.git

Always call mount with --no-canonicalize option

Always call mount with --no-canonicalize option to prevent symlink
attacks on mount.
---

diff --git a/ChangeLog b/ChangeLog
index 49f4e71..ff1c04f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -4,6 +4,9 @@
 	prevent symlink attacks at umount.  util-linux >= 2.18 or a
 	suitably patched version is required.
 
+	* Always call mount with --no-canonicalize option to prevent
+	symlink attacks on mount.
+
 2010-11-08  Miklos Szeredi <miklos@szeredi.hu>
 
 	* Open /dev/null for write instead of read for redirecting stdout
diff --git a/lib/mount_util.c b/lib/mount_util.c
index 4230e63..d008fcc 100644
--- a/lib/mount_util.c
+++ b/lib/mount_util.c
@@ -54,69 +54,6 @@ static int mtab_needs_update(const char *mnt)
 	return 1;
 }
 
-static int add_mount_legacy(const char *progname, const char *fsname,
-			    const char *mnt, const char *type, const char *opts)
-{
-	int res;
-	int status;
-	sigset_t blockmask;
-	sigset_t oldmask;
-
-	sigemptyset(&blockmask);
-	sigaddset(&blockmask, SIGCHLD);
-	res = sigprocmask(SIG_BLOCK, &blockmask, &oldmask);
-	if (res == -1) {
-		fprintf(stderr, "%s: sigprocmask: %s\n", progname, strerror(errno));
-		return -1;
-	}
-
-	res = fork();
-	if (res == -1) {
-		fprintf(stderr, "%s: fork: %s\n", progname, strerror(errno));
-		goto out_restore;
-	}
-	if (res == 0) {
-		char templ[] = "/tmp/fusermountXXXXXX";
-		char *tmp;
-
-		sigprocmask(SIG_SETMASK, &oldmask, NULL);
-		setuid(geteuid());
-
-		/*
-		 * hide in a directory, where mount isn't able to resolve
-		 * fsname as a valid path
-		 */
-		tmp = mkdtemp(templ);
-		if (!tmp) {
-			fprintf(stderr,
-				"%s: failed to create temporary directory\n",
-				progname);
-			exit(1);
-		}
-		if (chdir(tmp)) {
-			fprintf(stderr, "%s: failed to chdir to %s: %s\n",
-				progname, tmp, strerror(errno));
-			exit(1);
-		}
-		rmdir(tmp);
-		execl("/bin/mount", "/bin/mount", "-i", "-f", "-t", type,
-		      "-o", opts, fsname, mnt, NULL);
-		fprintf(stderr, "%s: failed to execute /bin/mount: %s\n",
-			progname, strerror(errno));
-		exit(1);
-	}
-	res = waitpid(res, &status, 0);
-	if (res == -1)
-		fprintf(stderr, "%s: waitpid: %s\n", progname, strerror(errno));
-
-	if (status != 0)
-		res = -1;
-
- out_restore:
-	sigprocmask(SIG_SETMASK, &oldmask, NULL);
-
-	return res;
-}
 
 static int add_mount(const char *progname, const char *fsname,
 		       const char *mnt, const char *type, const char *opts)
@@ -140,14 +77,6 @@ static int add_mount(const char *progname, const char *fsname,
 		goto out_restore;
 	}
 	if (res == 0) {
-		/*
-		 * Hide output, because old versions don't support
-		 * --no-canonicalize
-		 */
-		int fd = open("/dev/null", O_WRONLY);
-		dup2(fd, 1);
-		dup2(fd, 2);
-
 		sigprocmask(SIG_SETMASK, &oldmask, NULL);
 		setuid(geteuid());
 		execl("/bin/mount", "/bin/mount", "--no-canonicalize", "-i",
@@ -172,16 +101,10 @@ static int add_mount(const char *progname, const char *fsname,
 int fuse_mnt_add_mount(const char *progname, const char *fsname,
 		       const char *mnt, const char *type, const char *opts)
 {
-	int res;
-
 	if (!mtab_needs_update(mnt))
 		return 0;
 
-	res = add_mount(progname, fsname, mnt, type, opts);
-	if (res == -1)
-		res = add_mount_legacy(progname, fsname, mnt, type, opts);
-
-	return res;
+	return add_mount(progname, fsname, mnt, type, opts);
 }
 
 static int exec_umount(const char *progname, const char *rel_mnt, int lazy)