the build (oops!): replace calls to p_trespass() and PRISON_CHECK()
with p_can(..., {P_CAN_SEE, P_CAN_DEBUG}, NULL)
o Remove volatile usage from procfs_readdir() to remove warnings
o Apply bp's CREATE fix to linprocfs, causing EROFS to be returned on
CREATE calls to procfs_lookup()
o Some further synchronization still needs to occur: only existing
access checks were replaced, to fix the build--the new ones were not
added. I'll do this later today, this is a "fix the build quickly"
commit. This means that, in the interim, some information leakage
can still occur via linprocfs when using jail or kern.ps_showallprocs
Submitted by: knu
Approved by: des
Obtained from: TrustedBSD Project
