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bbfa235
(Get the code!)
Background:
In order to work around the mmap_min_addr setting introduced a while back that breaks Wine, many Wine packages now install conf files to /etc/sysctl.d/ that disable mmap_min_addr entirely. This reduces security of the system, as any kernel null pointer dereference bug can root the machine. One such bug was found to be open for 8 years.
This launchpad bug gives hints at what we need to do to implement this within Wine properly.
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From Launchpad:
I would like to see wine and dosemu using filesystem capabilties to temporarily grant themselves CAP_SYS_RAWIO during start up to map the memory below mmap_min_addr, instead of requiring that the entire running system have their mmap_min_addr lowered.
Implementing this would involve two halves: setting up the filesystem capabilities when the package installed (postinst most likely), and dropping the capability once the program had allocated memory.
Here is a quick example of how to mark an executable with a capability:
http://
They use numeric values, but it may be more readable to use text version:
sudo setcap cap_sys_rawio=ep low-mmap
(setcap is in libcap2-bin)
Part 2 involves dropping the capability:
http://
the pa_drop_caps and shows how to drop capabilities, and pa_have_caps shows how to test for a specific capability. (In the example's case, CAP_SYS_NICE.)
(sorry, lost some context for my setcap paste: "low-mmap" is the program I was setting capabilities on. "cap_sys_rawio" is the textual version of the capabilities.)