changed proc permissions in 2.4

[Olaf Hering]

Hi,

there seems to be a bug in the /proc permissions handling. What I need
is a proc mount in a build chroot. This build chroot should not change
the settings on the build host, therefore its mounted read only. This
was ok with 2.2 kernels.
The 2.4 kernel has appearently only one "handler" for the proc
permissions:

fig:~/lsof # cat /proc/mounts | grep proc
proc /proc proc ro 0 0
/proc/bus/usb /proc/bus/usb usbdevfs rw 0 0

fig:~/lsof # remount rw /proc/

fig:~/lsof # cat /proc/mounts | grep proc
proc /proc proc rw 0 0
/proc/bus/usb /proc/bus/usb usbdevfs rw 0 0

fig:~/lsof # mount -oro -n -tproc none proc 

fig:~/lsof # cat /proc/mounts | grep proc
proc /proc proc ro 0 0
/proc/bus/usb /proc/bus/usb usbdevfs rw 0 0
none /root/lsof/proc proc ro 0 0

fig:~/lsof # remount rw /proc/

fig:~/lsof # cat /proc/mounts | grep proc
proc /proc proc rw 0 0
/proc/bus/usb /proc/bus/usb usbdevfs rw 0 0
none /root/lsof/proc proc rw 0 0

fig:~/lsof # umount proc/

fig:~/lsof # mount -oro -n -tproc proc proc 

fig:~/lsof # cat /proc/mounts | grep proc
proc /proc proc ro 0 0
/proc/bus/usb /proc/bus/usb usbdevfs rw 0 0
proc /root/lsof/proc proc ro 0 0

fig:~/lsof # cat /proc/version 
Linux version 2.4.1-olaf-loop-nohighmem (root@mandarine) (gcc version
2.95.2 19991024 (release)) #1 Tue Feb 6 13:35:53 GMT 2001

this is the 2.2 test:
grapefruit:~ # mkdir blah
grapefruit:~ # cd blah/
grapefruit:~/blah # mkdir proc
grapefruit:~/blah # cat /proc/mounts | grep proc
proc /proc proc rw 0 0
grapefruit:~/blah # mount -oro -n -tproc none proc
grapefruit:~/blah # cat /proc/mounts | grep proc
proc /proc proc rw 0 0
none proc proc ro 0 0

grapefruit:~/blah # cat /proc/version 
Linux version 2.2.16 ([e-mail]) (gcc version 2.95.3 19991030
(prerelease/franzo/20000625)) #1 Thu Sep 28 08:48:06 GMT 2000

Is this the way it should be? 
The real problem is X, it tries to open /proc/bus/pci/*/* rw, that
fails, no devices detected. Its all on ppc, just in case that matters.

Gruss Olaf

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