RHEL 6.3: authd and negative UIDs
Environment
Red Hat Enterprise Linux (RHEL) 6.3
kernel 2.6.32-279.el6.x86_64
authd-1.4.3-30.el6
Issue
Getting NO-USER response from in.authd when it should return a valid user, e.g.:
# echo "5302,38506" | nc 127.0.0.1 113
5302 , 38506 : ERROR :NO-USER
Resolution
Updated authd packages that fix this issue are now available for Red Hat Enterprise Linux 6 in advisory RHBA-2013-1168.
Root Cause
If authd encountered a negative UID when reading a /proc/net/tcp entry then it stopped reading at that point and failed to identify the connection it was looking for. Consequently, authd returned a "non-existent user" error response. With the update provided in advisory RHBA-2013-1168, the handling of negative UID values in authd is modified, and authd correctly reports a valid user.
Diagnostic Steps
- Analysis revealed the source of the problem to be the negative UID in the UID column of
/proc/net/tcp. - Issue is similar to Bug 482811 - authd fails with negative uid values.
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