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Joachim Wiberg
63aabaa6df
On the local bus SO_PEERCRED says who is calling and the kernel is the one saying it. Behind a broker one connection carries every caller, so that credential describes dbus-daemon and nothing else, and every privileged method was refused there, root included. Ask the bus driver instead. libink parks the call and hands us the sender; we ask GetConnectionUnixUser and answer when the reply lands, through the same event loop as everything else. Nothing blocks: blocking in PID 1 is why libuEv exists. That needs calls libink can make on a connection it already has, so it gained those too. Answers are cached, since a bus never reuses a unique name while it runs. Not across a restart though: a new dbus-daemon numbers from scratch and :1.7 becomes somebody else, so the cache goes when the broker does. A sender name too long to key on is refused rather than truncated, two callers sharing a truncated key would share an identity. Privilege is no longer uid 0 alone. The socket is already owned by the --with-group group, so refusing its members every method that changes anything left a wheel user able to open the bus and unable to reboot. Both gates now say the same thing. Group membership needs NSS, which the C library loads with dlopen(), so the lookup is compiled out where Finit is built to link statically. That leaves such a build root-only, which is worth saying out loud rather than leaving to be discovered. Signed-off-by: Joachim Wiberg <troglobit@gmail.com>