Re: Mounting MFS filesystem does not preserve directory permissions of mount point

[Stuart Henderson]

On 2020/05/19 11:36, Andreas Kusalananda Kähäri wrote:
> >Synopsis:    Mounting MFS filesystem does not preserve directory permissions 
> >of mount point
> >Category:    system
> >Environment:
>       System      : OpenBSD 6.7
>       Details     : OpenBSD 6.7-current (GENERIC.MP) #198: Mon May 18 
> 20:33:28 MDT 2020
>                        
> dera...@amd64.openbsd.org:/usr/src/sys/arch/amd64/compile/GENERIC.MP
> 
>       Architecture: OpenBSD.amd64
>       Machine     : amd64
> >Description:
> 
> I've notice that with the most recent snapshot, the permissions of my
> /tmp directory, mounted as a MFS filesystem, were wrong:
> 
>       $ ls -ld /tmp
>       drwxr-xr-x  2 root  wheel  512 May 19 11:23 /tmp
> 
> This filesystem is mounted via fstab:
> 
>       swap    /tmp    mfs     rw,nodev,nosuid,-s1G
> 
> ... and the mount point has the correct permissions:
> 
>       $ doas umount /tmp
>       $ ls -ld /tmp
>       drwxrwxrwt  7 root  wheel  512 May 19 11:23 /tmp

OK?

Index: mkfs.c
===================================================================
RCS file: /cvs/src/sbin/newfs/mkfs.c,v
retrieving revision 1.98
diff -u -p -r1.98 mkfs.c
--- mkfs.c      3 Jul 2019 03:24:02 -0000       1.98
+++ mkfs.c      19 May 2020 11:43:30 -0000
@@ -134,7 +134,7 @@ static int  ilog2(int);
 void           initcg(int, time_t);
 void           wtfs(daddr_t, int, void *);
 int            fsinit1(time_t, mode_t, uid_t, gid_t);
-int            fsinit2(time_t);
+int            fsinit2(time_t, mode_t, uid_t, gid_t);
 int            makedir(struct direct *, int);
 void           iput(union dinode *, ino_t);
 void           setblock(struct fs *, unsigned char *, int);
@@ -590,7 +590,7 @@ mkfs(struct partition *pp, char *fsys, i
                sblock.fs_ffs1_cstotal.cs_nifree = sblock.fs_cstotal.cs_nifree;
                sblock.fs_ffs1_cstotal.cs_nffree = sblock.fs_cstotal.cs_nffree;
        } else {
-               if (fsinit2(utime))
+               if (fsinit2(utime, mfsmode, mfsuid, mfsgid))
                        errx(32, "fsinit2 failed");
        }
 
@@ -841,7 +841,7 @@ fsinit1(time_t utime, mode_t mfsmode, ui
 }
 
 int
-fsinit2(time_t utime)
+fsinit2(time_t utime, mode_t mfsmode, uid_t mfsuid, gid_t mfsgid)
 {
        union dinode node;
 
@@ -856,9 +856,15 @@ fsinit2(time_t utime)
        /*
         * Create the root directory.
         */
-       node.dp2.di_mode = IFDIR | UMASK;
-       node.dp2.di_uid = geteuid();
-       node.dp2.di_gid = getegid();
+       if (mfs) {
+               node.dp2.di_mode = IFDIR | mfsmode;
+               node.dp2.di_uid = mfsuid;
+               node.dp2.di_gid = mfsgid;
+       } else {
+               node.dp2.di_mode = IFDIR | UMASK;
+               node.dp2.di_uid = geteuid();
+               node.dp2.di_gid = getegid();
+       }
        node.dp2.di_nlink = PREDEFDIR;
        node.dp2.di_size = makedir(root_dir, PREDEFDIR);