Reviewed by: jlemon

An initial tidyup of the mount() syscall and VFS mount code.

This code replaces the earlier work done by jlemon in an attempt to
make linux_mount() work.

* the guts of the mount work has been moved into vfs_mount().

* move `type', `path' and `flags' from being userland variables into being
  kernel variables in vfs_mount(). `data' remains a pointer into
  userspace.

* Attempt to verify the `type' and `path' strings passed to vfs_mount()
  aren't too long.

* rework mount() and linux_mount() to take the userland parameters
  (besides data, as mentioned) and pass kernel variables to vfs_mount().
  (linux_mount() already did this, I've just tidied it up a little more.)

* remove the copyin*() stuff for `path'. `data' still requires copyin*()
  since its a pointer into userland.

* set `mount->mnt_statf_mntonname' in vfs_mount() rather than in each
  filesystem.  This variable is generally initialised with `path', and
  each filesystem can override it if they want to.

* NOTE: f_mntonname is intiailised with "/" in the case of a root mount.

1 files changed, 11 insertions, 5 deletions

diff --git a/sys/gnu/fs/ext2fs/ext2_vfsops.c b/sys/gnu/fs/ext2fs/ext2_vfsops.c
index 5ef3819..263db6d 100644
--- a/sys/gnu/fs/ext2fs/ext2_vfsops.c
+++ b/sys/gnu/fs/ext2fs/ext2_vfsops.c
@@ -192,7 +192,11 @@ ext2_mount(mp, path, data, ndp, p)
 	int error, flags;
 	mode_t accessmode;
 
-	if ((error = copyin(data, (caddr_t)&args, sizeof (struct ufs_args))) != 0)
+	/* Double-check the length of path.. */
+	if (strlen(path) >= MAXMNTLEN - 1)
+		return (ENAMETOOLONG);
+	error = copyin(data, (caddr_t)&args, sizeof (struct ufs_args));
+	if (error != 0)
 		return (error);
 	/*
 	 * If updating, check whether changing from read-only to
@@ -308,10 +312,12 @@ ext2_mount(mp, path, data, ndp, p)
 	}
 	ump = VFSTOUFS(mp);
 	fs = ump->um_e2fs;
-	(void) copyinstr(path, fs->fs_fsmnt, sizeof(fs->fs_fsmnt) - 1, &size);
-	bzero(fs->fs_fsmnt + size, sizeof(fs->fs_fsmnt) - size);
-	bcopy((caddr_t)fs->fs_fsmnt, (caddr_t)mp->mnt_stat.f_mntonname,
-	    MNAMELEN);
+	/*
+	 * Note that this strncpy() is ok because of a check at the start
+	 * of ext2_mount().
+	 */
+	strncpy(fs->fs_fsmnt, path, MAXMNTLEN);
+	fs->fs_fsmnt[MAXMNTLEN - 1] = '\0';
 	(void) copyinstr(args.fspec, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 
 	    &size);
 	bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size);