Re: offsets for 64bit IPC mechanisms

[Linda Knippers <linda.knippers@hp.com>]

Steve Grubb wrote:
> Hello,
> 
> BZ 221663 was opened to report a problem with some test results. From the 
> bugzilla:
> 
> semctl(id, 0, IPC_RMID);
> Expected argument: a0 = SEMCTL, a1 = id, a2 = 0, a3 = 0 (IPC_RMID)
> Actual arguments seen in the audit log: a0 = SEMCTL, a1 = id, a2 = 0, a3 = 
> 0x100
> 
> msgctl(id, IPC_STAT, &buf)
> Expected argument: a0 = MSGCTL, a1 = id, a2 = 2 (IPC_STAT)
> Actual arguments seen in the audit log: a0 = MSGCTL, a1 = id, a2 = 0x102
> 
> The answer was:
> 
> /*
>  * Version flags for semctl, msgctl, and shmctl commands
>  * These are passed as bitflags or-ed with the actual command
>  */
> #define IPC_OLD 0       /* Old version (no 32-bit UID support on many
>                            architectures) */
> #define IPC_64  0x0100  /* New version (support 32-bit UIDs, bigger
>                            message sizes, etc. */
> 
> Looks like userspace will "or" the value with IPC_64 to indicate the version 
> it supports.
> 
> 
> So the question is, should ausearch report the actual recorded register value, 
> or should it "and" the register with IPC_64 ?

Since we're auditing syscalls, I think audit should report what the
syscall sees.

-- ljk