OpenAFS Master Repository branch, master, updated. BP-openafs-stable-1_8_x-545-g57b4f4f

[Gerrit Code Review]

The following commit has been merged in the master branch:
commit 57b4f4f9be1e25d5609301c10f717aff32aef676
Author: Andrew Deason <adeason@sinenomine.net>
Date:   Fri Mar 13 13:00:35 2020 -0500

    LINUX: Properly revert creds in osi_UFSTruncate
    
    Commit cd3221d3 (Linux: use override_creds when available) caused us
    to force the current process's creds to the creds of afsd during
    osi_file.c file ops, to avoid access errors in some cases.
    
    However, in osi_UFSTruncate, one code path was missed to revert our
    creds back to the original user's creds: when the afs_osi_Stat call
    fails or deems the truncate unnecessary. In this case, the calling
    process keeps the creds for afsd after osi_UFSTruncate returns,
    causing our subsequent access-checking code to think that the current
    process is in the same context as afsd (typically uid 0 without a
    pag).
    
    This can cause the calling process to appear to transiently have the
    same access as non-pag uid 0; typically this will be unauthenticated
    access, but could be authenticated if uid 0 has tokens.
    
    To fix this, modify the early return in osi_UFSTruncate to go through
    a 'goto done' destructor instead, and make sure we revert our creds in
    that destructor.
    
    Thanks to cwills@sinenomine.net for finding and helping reproduce the
    issue.
    
    Change-Id: I6820af675edcb7aa00542ba40fc52430d68c05e8
    Reviewed-on: https://gerrit.openafs.org/14098
    Tested-by: BuildBot <buildbot@rampaginggeek.com>
    Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
    Reviewed-by: Jeffrey Hutzelman <jhutz@cmu.edu>
    Reviewed-by: Cheyenne Wills <cwills@sinenomine.net>
    Tested-by: Cheyenne Wills <cwills@sinenomine.net>

 src/afs/LINUX/osi_file.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

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