kernel/sysctl.c: add cap_last_cap to /proc/sys/kernel

Userspace needs to know the highest valid capability of the running
kernel, which right now cannot reliably be retrieved from the header files
only.  The fact that this value cannot be determined properly right now
creates various problems for libraries compiled on newer header files
which are run on older kernels.  They assume capabilities are available
which actually aren't.  libcap-ng is one example.  And we ran into the
same problem with systemd too.

Now the capability is exported in /proc/sys/kernel/cap_last_cap.

[[email protected]: make cap_last_cap const, per Ulrich]
Signed-off-by: Dan Ballard <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Lennart Poettering <[email protected]>
Cc: Kay Sievers <[email protected]>
Cc: Ulrich Drepper <[email protected]>
Cc: James Morris <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions