fusermount: only allow mount and umount if util-linux suppports --no-canonicalize

Miklos Szeredi · Miklos Szeredi · commit cbd3a2a84068 · 2011-01-31T16:33:22.000+01:00
Remove "legacy" util-linux support as missing --no-canonicalize cannot
be worked around in fuse.
diff --git a/ChangeLog b/ChangeLog
@@ -5,6 +5,9 @@
 
 	* fusermount: chdir to / before performing mount/umount
 
+	* fusermount: only allow mount and umount if util-linux supports
+	--no-canonicalize
+
 2010-12-16  Miklos Szeredi <miklos@szeredi.hu>
 
 	* Highlevel lib: allow hash tables to shrink
diff --git a/configure.in b/configure.in
@@ -33,8 +33,6 @@ AC_ARG_ENABLE(example,
 	[  --enable-example        Compile with examples ])
 AC_ARG_ENABLE(mtab,
 	[  --disable-mtab          Disable and ignore usage of /etc/mtab ])
-AC_ARG_ENABLE(legacy-umount,
-	[  --disable-legacy-umount If umount(8) is util-linux-ng >= 2.18 ])
 
 AC_ARG_WITH(pkgconfigdir,
             [  --with-pkgconfigdir=DIR      pkgconfig file in DIR @<:@LIBDIR/pkgconfig@:>@],
@@ -57,10 +55,6 @@ if test "$enable_mtab" = "no"; then
 	AC_DEFINE(IGNORE_MTAB, 1, [Don't update /etc/mtab])
 fi
 
-if test "$enable_legacy_umount" != "no"; then
-	AC_DEFINE(LEGACY_UMOUNT, 1, [Enable legacy umount support])
-fi
-
 AC_CHECK_FUNCS([fork setxattr fdatasync])
 AC_CHECK_MEMBERS([struct stat.st_atim])
 AC_CHECK_MEMBERS([struct stat.st_atimespec])
diff --git a/lib/mount_util.c b/lib/mount_util.c
@@ -73,70 +73,6 @@ static int mtab_needs_update(const char *mnt)
 }
 #endif /* __NetBSD__ */
 
-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)
 {
@@ -191,16 +127,10 @@ 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)
diff --git a/util/fusermount.c b/util/fusermount.c
@@ -382,54 +382,6 @@ static int chdir_to_parent(char *copy, const char **lastp)
 	return 0;
 }
 
-static int unmount_fuse_legacy(const char *mnt, int lazy)
-{
-	char *copy;
-	const char *last;
-	int res;
-
-	copy = strdup(mnt);
-	if (copy == NULL) {
-		fprintf(stderr, "%s: failed to allocate memory\n", progname);
-		return -1;
-	}
-
-	res = chdir_to_parent(copy, &last);
-	if (res == -1)
-		goto out;
-
-	res = check_is_mount(last, mnt);
-	if (res == -1)
-		goto out;
-
-	res = fuse_mnt_umount(progname, mnt, last, lazy);
-
-out:
-	free(copy);
-
-	return res;
-}
-
-static int unmount_fuse_nofollow(const char *mnt, int quiet, int lazy)
-{
-	int res;
-	int umount_flags = UMOUNT_NOFOLLOW;
-
-	if (lazy)
-		umount_flags |= UMOUNT_DETACH;
-
-	res = umount2(mnt, umount_flags);
-	if (res == -1) {
-		if (!quiet) {
-			fprintf(stderr, "%s: failed to unmount %s: %s\n",
-				progname, mnt, strerror(errno));
-		}
-		return -1;
-	}
-
-	return fuse_mnt_remove_mount(progname, mnt);
-}
-
 /* Check whether the kernel supports UMOUNT_NOFOLLOW flag */
 static int umount_nofollow_support(void)
 {
@@ -444,104 +396,49 @@ static int umount_nofollow_support(void)
 	return 1;
 }
 
-#ifdef LEGACY_UMOUNT
-/* Check if umount(8) supports "--fake" and "--no-canonicalize" options */
-static int umount_fake_support(void)
-{
-	int res;
-	int status;
-	sigset_t blockmask;
-	sigset_t oldmask;
-	int pip[2];
-	char buf[1024];
-	char *s;
-	unsigned majver;
-	unsigned minver;
-	int supported = 0;
-	int pid;
-
-	res = pipe(pip);
-	if (res == -1)
-		return 0;
-
-	sigemptyset(&blockmask);
-	sigaddset(&blockmask, SIGCHLD);
-	res = sigprocmask(SIG_BLOCK, &blockmask, &oldmask);
-	if (res == -1)
-		goto out_close;
-
-	pid = fork();
-	if (pid == -1)
-		goto out_restore;
-
-	if (pid == 0) {
-		int nullfd;
-
-		close(pip[0]);
-		dup2(pip[1], 1);
-		if (pip[1] != 1)
-			close(pip[1]);
-		nullfd = open("/dev/null", O_WRONLY);
-		dup2(nullfd, 2);
-		sigprocmask(SIG_SETMASK, &oldmask, NULL);
-		setuid(getuid());
-		execl("/bin/umount", "/bin/umount", "--version", NULL);
-		exit(1);
-	}
-	res = read(pip[0], buf, sizeof(buf));
-	if (res == -1 || res == sizeof(buf))
-		buf[0] = '\0';
-	else
-		buf[res] = '\0';
-
-	res = waitpid(pid, &status, 0);
-	if (res == -1 || status != 0)
-		goto out_restore;
-
-	s = strstr(buf, "util-linux-ng ");
-	if (s == NULL)
-		goto out_restore;
-
-	s += 14;
-	if (sscanf(s, "%u.%u", &majver, &minver) < 2)
-		goto out_restore;
-
-	if (majver < 2 || (majver == 2 && minver < 18))
-		goto out_restore;
-
-	supported = 1;
-
-out_restore:
-	sigprocmask(SIG_SETMASK, &oldmask, NULL);
-out_close:
-	close(pip[0]);
-	close(pip[1]);
-
-	return supported;
-}
-#else
-static int umount_fake_support(void)
-{
-	return 1;
-}
-#endif
-
 static int unmount_fuse_locked(const char *mnt, int quiet, int lazy)
 {
 	int res;
+	char *copy;
+	const char *last;
+	int umount_flags = lazy ? UMOUNT_DETACH : 0;
 
 	if (getuid() != 0) {
 		res = may_unmount(mnt, quiet);
 		if (res == -1)
 			return -1;
 	}
 
-	if (umount_nofollow_support() && umount_fake_support())
-		res = unmount_fuse_nofollow(mnt, quiet, lazy);
-	else
-		res = unmount_fuse_legacy(mnt, lazy);
+	copy = strdup(mnt);
+	if (copy == NULL) {
+		fprintf(stderr, "%s: failed to allocate memory\n", progname);
+		return -1;
+	}
 
-	return res;
+	res = chdir_to_parent(copy, &last);
+	if (res == -1)
+		goto out;
+
+	if (umount_nofollow_support()) {
+		umount_flags |= UMOUNT_NOFOLLOW;
+	} else {
+		res = check_is_mount(last, mnt);
+		if (res == -1)
+			goto out;
+	}
+
+	res = umount2(last, umount_flags);
+	if (res == -1 && !quiet) {
+		fprintf(stderr, "%s: failed to unmount %s: %s\n",
+			progname, mnt, strerror(errno));
+	}
+
+out:
+	chdir("/");
+	if (res == -1)
+		return -1;
+
+	return fuse_mnt_remove_mount(progname, mnt);
 }
 
 static int unmount_fuse(const char *mnt, int quiet, int lazy)
