Further shmctl() SHM_LOCK strangeness

["Michael Kerrisk" <mtk-lkml@gmx.net>]

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Manfred, Hugh,

While studying the RLIMIT_MEMLOCK stuff further, I came 
up with another observation: a process can perform a
shmctl(SHM_LOCK) on *any* System V shared memory segment, 
regardles of the segment's ownership or permissions,
providing the size of the segment falls within the 
process's RLIMIT_MEMLOCK limit.

Is this intended behaviour?  For most other System V IPC 
"ctl" operations the process must either:

1. be the owner of the object or have an appropriate 
   capability, or

2. have suitable permissions on the object.

Which of these two conditions applies depends on the
"ctl" operation.

Cheers,

Michael

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