fsuid0 caps

[M.L.PrasannaK.R.]

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In reply to
ttp://www.uwsg.iu.edu/hypermail/linux/kernel/0204.3/0380.html

This is documentation error. There is also a break in default
semantics of uid0 that needs to be fixed.
It is not a security hole as it results in the reduced capabilities
rather than in the increased capabilities.

setresuid(x,x,-1) clears effective caps.
setfsuid(0) rstores CAP_FS_MASK effective caps.
setresuid(-1,-1,x) clears both effective and permitted caps.
Both fs and non fs caps are lost.

This results in uid0 with no capabilties and no way of
restoring them. If this is valid issue, something like
the following patch fixes it.

Thanks,
MLPKR.

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