[Bug libc/5778] New: pathconf(path,_PC_CHOWN_RESTRICTED) does not work correctly under Linux

[Bug libc/5778] New: pathconf(path,_PC_CHOWN_RESTRICTED) does not work correctly under Linux

[axel dot philipp at mtu dot de]

pathconf(path,_PC_CHOWN_RESTRICTED)always returns POSIX_CHOWN_RESTRICTED even 
if the filesystem where path is located is configured to allow unrestricted 
chown. 

This seems to be an inconsistency between kernel, glibc and LSB. although the 
Linux syscall chown allows unpriviliged users to chown files if the filesystem 
does, LSB 3.2 core generic para. 13.4.79 mandates that POSIX_CHOWN_RESTRICTED 
be defined as 1. This variable should be undefined because that feature 
definitely depends on filesystem and need not be the same for all fs on a host.

But even if POSIX_CHOWN_RESTRICTED were undefined, pathconf would return the 
wrong value since it always returns -1 in that case.

I checked today http://sources.redhat.com/cgi-
bin/cvsweb.cgi/libc/sysdeps/posix/?cvsroot=glibc, pathconf.c is the same since 
2003, I tested with 2.3.5.

Filesystems with unrestricted chown can be local (XFS 
with /proc/sys/fs/xfs/restrict_chown=0) or NFS mounted.

-- 
           Summary: pathconf(path,_PC_CHOWN_RESTRICTED) does not work
                    correctly under Linux
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: drepper at redhat dot com
        ReportedBy: axel dot philipp at mtu dot de
                CC: glibc-bugs at sources dot redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=5778

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[Bug libc/5778] pathconf(path,_PC_CHOWN_RESTRICTED) does not work correctly under Linux

[drepper at redhat dot com]

------- Additional Comments From drepper at redhat dot com  2008-03-08 01:58 -------
When the pathconf code was written xfs didn't exist for Linux.  I've changed it.
 What LSB is of no relevance, it has nothing whatsoever to do with glibc.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://sourceware.org/bugzilla/show_bug.cgi?id=5778

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[Bug libc/5778] pathconf(path,_PC_CHOWN_RESTRICTED) does not work correctly under Linux

[axel dot philipp at mtu dot de]

------- Additional Comments From axel dot philipp at mtu dot de  2008-03-10 16:17 -------
Thanks for the patch.
When I look at the explanation in posix/unistd.h
   If any is defined as other than -1, the corresponding
   option is true for all files.  If a symbol is not defined at all, the value
   for a specific file can be obtained from `pathconf' and `fpathconf'.
I wonder whether _POSIX_CHOWN_RESTRICTED shouldn't be undefined instead of 
being set to 0.

XFS was just an example. Linux also allows unrestricted chown on NFS mounted 
filesystems if the NFS server is configured so. It's certainly difficult for 
glibc to handle such cases as long as the kernel does not provide a query 
interface for pathconf. Perhaps errno could be set to EINVAL (in the meaning of 
not implemented) in such cases.

-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=5778

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[Bug libc/5778] pathconf(path,_PC_CHOWN_RESTRICTED) does not work correctly under Linux

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=5778

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
              Flags|                            |security-

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