Bugzilla Bug 93671

Man mount says regarding permissions of the mount point:
" The previous contents (if  any) and  owner  and  mode of dir become invisible,
[...]"
"Mount options for fat [...] umask=value [...] The default is the umask of the
current process."

I have a /dev/sda1, type msdos (for which fat mount options apply:
"Mount options for msdos: See  mount options for fat." (man mount)), and will try
mounting on /mnt/stick. Let's examine umask of current process:
kestrel root # umask 
0022
Now let's mount without specifying umask:
kestrel root # mount /dev/sda1 /mnt/stick
kestrel root # ls -lad /mnt/stick
drwxr--r--  4 root root 16384 Jan  1  1970 /mnt/stick
Now let's try specifying the current process umask explicitly (which shouldn't
have any effect, because according to the man page, is default anyway):
kestrel root # umount /dev/sda1
kestrel root # mount /dev/sda1 /mnt/stick -o umask=22
kestrel root # ls -lad /mnt/stick
drwxr-xr-x  4 root root 16384 Jan  1  1970 /mnt/stick

You can see, it has effect, and therefore the mount command is using incorrect
default umask.

Reproducible: Always
Steps to Reproduce:
1.
2.
3.




Portage 2.0.51.19 (default-linux/x86/2005.0, gcc-3.3.5-20050130,
glibc-2.3.4.20041102-r1, 2.6.11-gentoo-r5 i686)
================================================================= System uname:
2.6.11-gentoo-r5 i686 Intel(R) Pentium(R) M processor 1.50GHz Gentoo Base System
version 1.4.16 Python:              dev-lang/python-2.3.5 [2.3.5 (#1, May  4
2005, 16:17:52)] dev-lang/python:     2.3.5
sys-apps/sandbox:    [Not Present]
sys-devel/autoconf:  2.59-r6, 2.13
sys-devel/automake:  1.7.9-r1, 1.8.5-r3, 1.5, 1.4_p6, 1.6.3, 1.9.4
sys-devel/binutils:  2.15.92.0.2-r7
sys-devel/libtool:   1.5.16
virtual/os-headers:  2.6.8.1-r2
ACCEPT_KEYWORDS="x86"
AUTOCLEAN="yes"
CFLAGS="-O2 -march=pentium3 -fomit-frame-pointer -pipe"
CHOST="i686-pc-linux-gnu"
CONFIG_PROTECT="/etc /usr/kde/2/share/config /usr/kde/3.3/env
/usr/kde/3.3/share/config /usr/kde/3.3/shutdown /usr/kde/3/share/config
/usr/lib/X11/xkb /usr/lib/mozilla/defaults/pref /usr/share/config
/usr/share/texmf/dvipdfm/config/ /usr/share/texmf/dvips/config/
/usr/share/texmf/tex/generic/config/ /usr/share/texmf/tex/platex/config/
/usr/share/texmf/xdvi/ /var/qmail/control" CONFIG_PROTECT_MASK="/etc/gconf
/etc/terminfo /etc/env.d" CXXFLAGS="-O2 -march=pentium3 -fomit-frame-pointer
-pipe" DISTDIR="/usr/portage/distfiles" FEATURES="autoaddcvs autoconfig ccache
distlocks sandbox sfperms strict" GENTOO_MIRRORS="http://distfiles.gentoo.org
http://distro.ibiblio.org/pub/Linux/distributions/gentoo" MAKEOPTS="-j2"
PKGDIR="/usr/portage/packages" PORTAGE_TMPDIR="/var/tmp" PORTDIR="/usr/portage"
SYNC="rsync://rsync.gentoo.org/gentoo-portage" USE="x86 X alsa apm arts avi
berkdb bitmap-fonts cdr crypt cups curl emboss encode esd fam foomaticdb fortran
gdbm gif gpm gtk gtk2 guile imagemagick imap imlib ipv6 jack java jpeg kde ldap
libg++ libwww mad mikmod motif mozilla mp3 mpeg mysql ncurses nls ogg oggvorbis
opengl oss pam pdflib perl png python qt quicktime readline ruby samba sdl slang
spell ssl svga tcltk tcpd tetex tiff tls truetype truetype-fonts type1-fonts
vorbis xine xml2 xmms xv zlib userland_GNU kernel_linux elibc_glibc" Unset: 
ASFLAGS, CBUILD, CTARGET, LANG, LC_ALL, LDFLAGS, LINGUAS, PORTDIR_OVERLAY

This is not a mount bug, but a kernel-bug. umask=nnn is passed along other
user-flags to the mount syscall as a string, and the kernel-filesystem driver
parses the string and denies the syscall if a syntax-error occures. Not all
filesystems supports umask, so umask is not sent unless spesified. If the mount
man-page claims that umask is defaulted to the current shell umask setting, the
kernel-driver needs to take this into account when umask isn't found in the
string it receives from user-space. Just my 5 cent about this bug

sounds convincing to me :)

iirc, last time i tried using umask, ntfs suffered from similar issues ... but
that was a while ago

mount bug. Attaching patch against util-linux which I will send upstream for
comments.

Created an attachment (id=64688) [details]
Don't set umask in mount

Patch does make sense (if the default is to use current process's umask, it
should not explicitly set it to 022 ...) ... Daniel, did they get back to you?

i havent looked through the code but wouldnt the best change be to set
umask(022) if the user did not specify the umask option ?

The reason it was added was to prevent the temporary files (e.g. /etc/mtab~)
being writable because this can lead to the user getting a root shell.

However, I went through the code, and theres only one place where theres a
chance of a writable file being created, and the umask is already controlled (it
sets to 022, creates file, then restores the umask).

I've had no response from the upstream maintainer but just sent another email.

Adrian Bunk (upstream maintainer) replies:

"sorry, this patch is still part of the big batch of util-linux emails I 
have to go through."

I think its safe to assume this patch is valid. Please include in the ebuild.

added to 2.12q-r1