linux-stable/security
Linus Torvalds f122a08b19 capability: just use a 'u64' instead of a 'u32[2]' array
Back in 2008 we extended the capability bits from 32 to 64, and we did
it by extending the single 32-bit capability word from one word to an
array of two words.  It was then obfuscated by hiding the "2" behind two
macro expansions, with the reasoning being that maybe it gets extended
further some day.

That reasoning may have been valid at the time, but the last thing we
want to do is to extend the capability set any more.  And the array of
values not only causes source code oddities (with loops to deal with
it), but also results in worse code generation.  It's a lose-lose
situation.

So just change the 'u32[2]' into a 'u64' and be done with it.

We still have to deal with the fact that the user space interface is
designed around an array of these 32-bit values, but that was the case
before too, since the array layouts were different (ie user space
doesn't use an array of 32-bit values for individual capability masks,
but an array of 32-bit slices of multiple masks).

So that marshalling of data is actually simplified too, even if it does
remain somewhat obscure and odd.

This was all triggered by my reaction to the new "cap_isidentical()"
introduced recently.  By just using a saner data structure, it went from

	unsigned __capi;
	CAP_FOR_EACH_U32(__capi) {
		if (a.cap[__capi] != b.cap[__capi])
			return false;
	}
	return true;

to just being

	return a.val == b.val;

instead.  Which is rather more obvious both to humans and to compilers.

Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Paul Moore <paul@paul-moore.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2023-03-01 10:01:22 -08:00
..
apparmor capability: just use a 'u64' instead of a 'u32[2]' array 2023-03-01 10:01:22 -08:00
bpf
integrity powerpc updates for 6.3 2023-02-25 11:00:06 -08:00
keys This update includes the following changes: 2023-02-21 18:10:50 -08:00
landlock landlock: Support file truncation 2022-10-19 09:01:44 +02:00
loadpin LoadPin: Allow filesystem switch when not enforcing 2023-01-19 15:18:20 -08:00
lockdown lockdown: ratelimit denial messages 2022-09-14 07:37:50 -04:00
safesetid LSM: SafeSetID: Add setgroups() security policy handling 2022-07-15 18:24:42 +00:00
selinux - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
smack One fix for resetting CIPSO labeling. 2023-02-22 12:52:59 -08:00
tomoyo tomoyo: Update website link 2023-01-13 23:11:38 +09:00
yama
commoncap.c capability: just use a 'u64' instead of a 'u32[2]' array 2023-03-01 10:01:22 -08:00
device_cgroup.c device_cgroup: Roll back to original exceptions after copy failure 2022-11-16 18:28:55 -05:00
inode.c
Kconfig x86/retbleed: Add fine grained Kconfig knobs 2022-06-29 17:43:41 +02:00
Kconfig.hardening randstruct: disable Clang 15 support 2023-02-08 15:26:58 -08:00
lsm_audit.c audit: Fix some kernel-doc warnings 2022-10-28 06:37:55 -04:00
Makefile security: remove unneeded subdir-$(CONFIG_...) 2021-09-03 08:17:20 +09:00
min_addr.c
security.c integrity-v6.3 2023-02-22 12:36:25 -08:00