80 lines
2.5 KiB
Plaintext
80 lines
2.5 KiB
Plaintext
|
Notes on the change from 16-bit UIDs to 32-bit UIDs:
|
||
|
|
|
||
|
|
- kernel code MUST take into account __kernel_uid_t and __kernel_uid32_t
|
||
|
|
when communicating between user and kernel space in an ioctl or data
|
||
|
|
structure.
|
||
|
|
|
||
|
|
- kernel code should use uid_t and gid_t in kernel-private structures and
|
||
|
|
code.
|
||
|
|
|
||
|
|
What's left to be done for 32-bit UIDs on all Linux architectures:
|
||
|
|
|
||
|
|
- Disk quotas have an interesting limitation that is not related to the
|
||
|
|
maximum UID/GID. They are limited by the maximum file size on the
|
||
|
|
underlying filesystem, because quota records are written at offsets
|
||
|
|
corresponding to the UID in question.
|
||
|
|
Further investigation is needed to see if the quota system can cope
|
||
|
|
properly with huge UIDs. If it can deal with 64-bit file offsets on all
|
||
|
|
architectures, this should not be a problem.
|
||
|
|
|
||
|
|
- Decide whether or not to keep backwards compatibility with the system
|
||
|
|
accounting file, or if we should break it as the comments suggest
|
||
|
|
(currently, the old 16-bit UID and GID are still written to disk, and
|
||
|
|
part of the former pad space is used to store separate 32-bit UID and
|
||
|
|
GID)
|
||
|
|
|
||
|
|
- Need to validate that OS emulation calls the 16-bit UID
|
||
|
|
compatibility syscalls, if the OS being emulated used 16-bit UIDs, or
|
||
|
|
uses the 32-bit UID system calls properly otherwise.
|
||
|
|
|
||
|
|
This affects at least:
|
||
|
|
SunOS emulation
|
||
|
|
Solaris emulation
|
||
|
|
iBCS on Intel
|
||
|
|
|
||
|
|
sparc32 emulation on sparc64
|
||
|
|
(need to support whatever new 32-bit UID system calls are added to
|
||
|
|
sparc32)
|
||
|
|
|
||
|
|
- Validate that all filesystems behave properly.
|
||
|
|
|
||
|
|
At present, 32-bit UIDs _should_ work for:
|
||
|
|
ext2
|
||
|
|
ufs
|
||
|
|
isofs
|
||
|
|
nfs
|
||
|
|
coda
|
||
|
|
udf
|
||
|
|
|
||
|
|
Ioctl() fixups have been made for:
|
||
|
|
ncpfs
|
||
|
|
smbfs
|
||
|
|
|
||
|
|
Filesystems with simple fixups to prevent 16-bit UID wraparound:
|
||
|
|
minix
|
||
|
|
sysv
|
||
|
|
qnx4
|
||
|
|
|
||
|
|
Other filesystems have not been checked yet.
|
||
|
|
|
||
|
|
- The ncpfs and smpfs filesystems can not presently use 32-bit UIDs in
|
||
|
|
all ioctl()s. Some new ioctl()s have been added with 32-bit UIDs, but
|
||
|
|
more are needed. (as well as new user<->kernel data structures)
|
||
|
|
|
||
|
|
- The ELF core dump format only supports 16-bit UIDs on arm, i386, m68k,
|
||
|
|
sh, and sparc32. Fixing this is probably not that important, but would
|
||
|
|
require adding a new ELF section.
|
||
|
|
|
||
|
|
- The ioctl()s used to control the in-kernel NFS server only support
|
||
|
|
16-bit UIDs on arm, i386, m68k, sh, and sparc32.
|
||
|
|
|
||
|
|
- make sure that the UID mapping feature of AX25 networking works properly
|
||
|
|
(it should be safe because it's always used a 32-bit integer to
|
||
|
|
communicate between user and kernel)
|
||
|
|
|
||
|
|
|
||
|
|
Chris Wing
|
||
|
|
wingc@umich.edu
|
||
|
|
|
||
|
|
last updated: January 11, 2000
|