Correctly handle "user" and "users" mount options.

If "user" or "users" is given, then allow mount.nfs to be run
by a non-root user providing that the mountpoint, filesystem, and options
exactly match what is found in fstab.

For "user", record the user name in mtab so they can unmount the
filesystem later.

Also alwasys ignore auto, owner, group and their negations as well
as "_netdev", "comment" and "loop".

1 files changed, 57 insertions, 6 deletions

diff --git a/utils/mount/mount.c b/utils/mount/mount.c
index 0edcc1a..cdccfe8 100644
--- a/utils/mount/mount.c
+++ b/utils/mount/mount.c
@@ -28,6 +28,7 @@
 #include <sys/mount.h>
 #include <getopt.h>
 #include <mntent.h>
+#include <pwd.h>
 
 #include "fstab.h"
 #include "xcommon.h"
@@ -75,6 +76,11 @@ struct opt_map {
   int  mask;                    /* flag mask value */
 };
 
+/* Custom mount options for our own purposes.  */
+#define MS_DUMMY	0x00000000
+#define MS_USERS	0x40000000
+#define MS_USER		0x80000000
+
 static const struct opt_map opt_map[] = {
   { "defaults", 0, 0, 0         },      /* default options */
   { "ro",       1, 0, MS_RDONLY },      /* read-only */
@@ -91,6 +97,20 @@ static const struct opt_map opt_map[] = {
   { "remount",  0, 0, MS_REMOUNT},      /* Alter flags of mounted FS */
   { "bind",     0, 0, MS_BIND   },      /* Remount part of tree elsewhere */
   { "rbind",    0, 0, MS_BIND|MS_REC }, /* Idem, plus mounted subtrees */
+  { "auto",     0, 0, MS_DUMMY },       /* Can be mounted using -a */
+  { "noauto",   0, 0, MS_DUMMY },       /* Can  only be mounted explicitly */
+  { "users",    1, 0, MS_USERS|MS_NOEXEC|MS_NOSUID|MS_NODEV  },
+  					/* Allow ordinary user to mount */
+  { "nousers",  0, 1, MS_DUMMY  },      /* Forbid ordinary user to mount */
+  { "user",     1, 0, MS_USER|MS_NOEXEC|MS_NOSUID|MS_NODEV  },
+  					/* Allow ordinary user to mount */
+  { "nouser",   0, 1, MS_DUMMY   },     /* Forbid ordinary user to mount */
+  { "owner",    0, 0, MS_DUMMY  },      /* Let the owner of the device mount */
+  { "noowner",  0, 0, MS_DUMMY  },      /* Device owner has no special privs */
+  { "group",    0, 0, MS_DUMMY  },      /* Let the group of the device mount */
+  { "nogroup",  0, 0, MS_DUMMY  },      /* Device group has no special privs */
+  { "_netdev",  0, 0, MS_DUMMY},        /* Device requires network */
+  { "comment",  0, 0, MS_DUMMY},        /* fstab comment only (kudzu,_netdev)*/
 
   /* add new options here */
 #ifdef MS_NOSUB
@@ -105,6 +125,7 @@ static const struct opt_map opt_map[] = {
   { "mand",     0, 0, MS_MANDLOCK },    /* Allow mandatory locks on this FS */
   { "nomand",   0, 1, MS_MANDLOCK },    /* Forbid mandatory locks on this FS */
 #endif
+  { "loop",     1, 0, MS_DUMMY   },      /* use a loop device */
 #ifdef MS_NOATIME
   { "atime",    0, 1, MS_NOATIME },     /* Update access time */
   { "noatime",  0, 0, MS_NOATIME },     /* Do not update access time */
@@ -122,6 +143,15 @@ static char * fix_opts_string (int flags, const char *extra_opts) {
 	char *new_opts;
 
 	new_opts = xstrdup((flags & MS_RDONLY) ? "ro" : "rw");
+	if (flags & MS_USER) {
+		/* record who mounted this so they can unmount */
+		struct passwd *pw = getpwuid(getuid());
+		if(pw)
+			new_opts = xstrconcat3(new_opts, ",user=", pw->pw_name);
+	}
+	if (flags & MS_USERS)
+		new_opts = xstrconcat3(new_opts, ",users", "");
+	
 	for (om = opt_map; om->opt != NULL; om++) {
 		if (om->skip)
 			continue;
@@ -282,16 +312,12 @@ int main(int argc, char *argv[])
 	int c, flags = 0, nfs_mount_vers = 0, mnt_err = 1, fake = 0;
 	char *spec, *mount_point, *extra_opts = NULL;
 	char *mount_opts = NULL, *p;
+	uid_t uid = getuid();
 
 	progname = argv[0];
 	if ((p = strrchr(progname, '/')) != NULL)
 		progname = p+1;
 
-	if (getuid() != 0) {
-		printf("%s: only root can do that.\n", progname);
-		exit(1);
-	}
-
 	if(!strncmp(progname, "umount", strlen("umount"))) {
 		if(argc < 2) {
 			umount_usage();
@@ -375,10 +401,35 @@ int main(int argc, char *argv[])
 	}
 
 	spec = argv[1];
-	mount_point = canonicalize(argv[2]);
+	mount_point = argv[2];
+
+	if (uid != 0) {
+		/* don't even think about it unless options exactly
+		 * make fstab
+		 */
+		struct mntentchn *mc;
+
+		if ((mc = getfsfile(mount_point)) == NULL ||
+		    strcmp(mc->m.mnt_fsname, spec) != 0 ||
+		    strcmp(mc->m.mnt_opts, mount_opts) != 0) {
+			fprintf(stderr, "%s: permission died - no match for fstab\n",
+				progname);
+			exit(1);
+		}
+		mounttype = 0;
+	}
+
+	mount_point = canonicalize(mount_point);
 	
 	parse_opts(mount_opts, &flags, &extra_opts);
 
+	if (uid != 0) {
+	    if (! (flags & (MS_USERS | MS_USER))) {
+		    fprintf(stderr, "%s: permission denied\n", progname);
+		    exit(1);
+	    }
+	}
+
 	if (!strcmp(progname, "mount.nfs4") || nfs_mount_vers == 4) {
 		nfs_mount_vers = 4;
 		mnt_err = nfs4mount(spec, mount_point, &flags, &extra_opts, &mount_opts, 0);