On Tue, 24 Feb 2015, Serge Hallyn wrote:
Unless I'm misunderstanding what you are saying, apps do have surprises.
They drop capabilities, execute a file, and the result has capabilities
which the app couldn't have expected. At least if the bits have to be
in fI to become part of pP', the app has a clue.
Well yes but the surprises do not occur in the cap bits they are
manipulating or inspecting via prctl.
To be clear, I'm suggesting that the rules at exec become:
pI' = pI
Ok that is new and on its own may solve the issue?
pA' = pA (pA is ambient)
Thats what this patch does
pP' = (X & fP) | (pI & (fI | pA))
Hmmm... fP is empty for the file not having caps. so
pP' = pI & pA
pE' = pP' & fE
fE? So the inherited caps are not effective? fE would be empty for a file
not having caps thus the ambient caps would not be available in the child.