mount: plug a hole where FEATURE_MOUNT_HELPERS could allow execution

of arbitrary command.

function                                             old     new   delta
mount_it_now                                         266     309     +43

1 files changed, 22 insertions, 18 deletions

diff --git a/util-linux/mount.c b/util-linux/mount.c
index b19c3a3ef..e41707e38 100644
--- a/util-linux/mount.c
+++ b/util-linux/mount.c
@@ -56,9 +56,9 @@ static struct mntent *getmntent_r(FILE* stream, struct mntent* result, char* buf
 
 // Not real flags, but we want to be able to check for this.
 enum {
-        MOUNT_USERS  = (1<<28)*ENABLE_DESKTOP,
-        MOUNT_NOAUTO = (1<<29),
-        MOUNT_SWAP   = (1<<30),
+        MOUNT_USERS  = (1 << 28) * ENABLE_DESKTOP,
+        MOUNT_NOAUTO = (1 << 29),
+        MOUNT_SWAP   = (1 << 30),
 };
 
 
@@ -238,8 +238,7 @@ static int verbose_mount(const char *source, const char *target,
         errno = 0;
         rc = mount(source, target, filesystemtype, mountflags, data);
         if (verbose >= 2)
-                bb_perror_msg("would do mount('%s','%s','%s',0x%08lx,'%s'):%d"
-                                + (sizeof("would do ")-1),
+                bb_perror_msg("mount('%s','%s','%s',0x%08lx,'%s'):%d",
                         source, target, filesystemtype,
                         mountflags, (char*)data, rc);
         return rc;
@@ -407,7 +406,7 @@ static int mount_it_now(struct mntent *mp, long vfsflags, char *filteropts)
                 if (ENABLE_FEATURE_MOUNT_HELPERS && rc) {
                         char *args[6];
                         int errno_save = errno;
-                        args[0] = mp->mnt_type;
+                        args[0] = xasprintf("mount.%s", mp->mnt_type);
                         rc = 1;
                         if (filteropts) {
                                 args[rc++] = (char *)"-o";
@@ -417,6 +416,7 @@ static int mount_it_now(struct mntent *mp, long vfsflags, char *filteropts)
                         args[rc++] = mp->mnt_dir;
                         args[rc] = NULL;
                         rc = wait4pid(spawn(args));
+                        free(args[0]);
                         if (!rc)
                                 break;
                         errno = errno_save;
@@ -1556,8 +1556,8 @@ static int singlemount(struct mntent *mp, int ignore_busy)
 
         // Treat fstype "auto" as unspecified.
 
-        if (mp->mnt_type && strcmp(mp->mnt_type,"auto") == 0)
-                mp->mnt_type = 0;
+        if (mp->mnt_type && strcmp(mp->mnt_type, "auto") == 0)
+                mp->mnt_type = NULL;
 
         // Might this be a virtual filesystem?
 
@@ -1566,6 +1566,8 @@ static int singlemount(struct mntent *mp, int ignore_busy)
         ) {
                 char *s, *p, *args[35];
                 int n = 0;
+// FIXME: does it allow execution of arbitrary commands?!
+// What args[0] can end up with?
                 for (s = p = mp->mnt_fsname; *s && n < 35-3; ++s) {
                         if (s[0] == '#' && s[1] != '#') {
                                 *s = '\0';
@@ -1583,9 +1585,9 @@ static int singlemount(struct mntent *mp, int ignore_busy)
         // Might this be an CIFS filesystem?
 
         if (ENABLE_FEATURE_MOUNT_CIFS
-         && (!mp->mnt_type || strcmp(mp->mnt_type,"cifs") == 0)
-         && (mp->mnt_fsname[0]=='/' || mp->mnt_fsname[0]=='\\')
-         && mp->mnt_fsname[0]==mp->mnt_fsname[1]
+         && (!mp->mnt_type || strcmp(mp->mnt_type, "cifs") == 0)
+         && (mp->mnt_fsname[0] == '/' || mp->mnt_fsname[0] == '\\')
+         && mp->mnt_fsname[0] == mp->mnt_fsname[1]
         ) {
                 len_and_sockaddr *lsa;
                 char *ip, *dotted;
@@ -1725,7 +1727,9 @@ int mount_main(int argc, char **argv)
 {
         enum { OPT_ALL = 0x10 };
 
-        char *cmdopts = xstrdup(""), *fstype=0, *storage_path=0;
+        char *cmdopts = xstrdup("");
+        char *fstype = NULL;
+        char *storage_path = NULL;
         char *opt_o;
         const char *fstabname;
         FILE *fstab;
@@ -1744,7 +1748,7 @@ int mount_main(int argc, char **argv)
                         append_mount_options(&cmdopts, argv[i]+2);
                 } else argv[j++] = argv[i];
         }
-        argv[j] = 0;
+        argv[j] = NULL;
         argc = j;
 
         // Parse remaining options
@@ -1895,12 +1899,13 @@ int mount_main(int argc, char **argv)
 
                 } else {
                         // Do we need to match a filesystem type?
-                        if (fstype && match_fstype(mtcur, fstype)) continue;
+                        if (fstype && match_fstype(mtcur, fstype))
+                                continue;
 
                         // Skip noauto and swap anyway.
 
-                        if (parse_mount_options(mtcur->mnt_opts, 0)
-                                & (MOUNT_NOAUTO | MOUNT_SWAP)) continue;
+                        if (parse_mount_options(mtcur->mnt_opts, 0) & (MOUNT_NOAUTO | MOUNT_SWAP))
+                                continue;
 
                         // No, mount -a won't mount anything,
                         // even user mounts, for mere humans.
@@ -1909,9 +1914,8 @@ int mount_main(int argc, char **argv)
                                 bb_error_msg_and_die(must_be_root);
 
                         // Mount this thing.
-                        if (ENABLE_FEATURE_MOUNT_LABEL) {
+                        if (ENABLE_FEATURE_MOUNT_LABEL)
                                 resolve_mount_spec(&mtpair->mnt_fsname);
-                        }
 
                         // NFS mounts want this to be xrealloc-able
                         mtcur->mnt_opts = xstrdup(mtcur->mnt_opts);