apparmor: audit unknown signal numbers

Allow apparmor to audit the number of a signal that it does not
provide a mapping for and is currently being reported only as
unknown.

Signed-off-by: John Johansen <john.johansen@canonical.com>

apparmor: fix logging of the existence test for signals

The existence test is not being properly logged as the signal mapping
maps it to the last entry in the named signal table. This is done
to help catch bugs by making the 0 mapped signal value invalid so
that we can catch the signal value not being filled in.

When fixing the off-by-one comparision logic the reporting of the
existence test was broken, because the logic behind the mapped named
table was hidden. Fix this by adding a define for the name lookup
and using it.

Cc: Stable <stable@vger.kernel.org>
Fixes: f7dc4c9a855a1 ("apparmor: fix off-by-one comparison on MAXMAPPED_SIG")
Signed-off-by: John Johansen <john.johansen@canonical.com>

apparmor: fix build failure on sparc caused by undeclared signals

In file included from security/apparmor/ipc.c:23:0:
security/apparmor/include/sig_names.h:26:3: error: 'SIGSTKFLT' undeclared here (not in a function)
[SIGSTKFLT] = 16, /* -, 16, - */
^
security/apparmor/include/sig_names.h:26:3: error: array index in initializer not of integer type
security/apparmor/include/sig_names.h:26:3: note: (near initialization for 'sig_map')
security/apparmor/include/sig_names.h:51:3: error: 'SIGUNUSED' undeclared here (not in a function)
[SIGUNUSED] = 34, /* -, 31, - */
^
security/apparmor/include/sig_names.h:51:3: error: array index in initializer not of integer type
security/apparmor/include/sig_names.h:51:3: note: (near initialization for 'sig_map')

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: c6bf1adaecaa ("apparmor: add the ability to mediate signals")
Signed-off-by: John Johansen <john.johansen@canonical.com>

apparmor: add the ability to mediate signals

Add signal mediation where the signal can be mediated based on the
signal, direction, or the label or the peer/target. The signal perms
are verified on a cross check to ensure policy consistency in the case
of incremental policy load/replacement.

The optimization of skipping the cross check when policy is guaranteed
to be consistent (single compile unit) remains to be done.

policy rules have the form of
SIGNAL_RULE = [ QUALIFIERS ] 'signal' [ SIGNAL ACCESS PERMISSIONS ]
[ SIGNAL SET ] [ SIGNAL PEER ]

SIGNAL ACCESS PERMISSIONS = SIGNAL ACCESS | SIGNAL ACCESS LIST

SIGNAL ACCESS LIST = '(' Comma or space separated list of SIGNAL
ACCESS ')'

SIGNAL ACCESS = ( 'r' | 'w' | 'rw' | 'read' | 'write' | 'send' |
'receive' )

SIGNAL SET = 'set' '=' '(' SIGNAL LIST ')'

SIGNAL LIST = Comma or space separated list of SIGNALS

SIGNALS = ( 'hup' | 'int' | 'quit' | 'ill' | 'trap' | 'abrt' |
'bus' | 'fpe' | 'kill' | 'usr1' | 'segv' | 'usr2' |
'pipe' | 'alrm' | 'term' | 'stkflt' | 'chld' | 'cont' |
'stop' | 'stp' | 'ttin' | 'ttou' | 'urg' | 'xcpu' |
'xfsz' | 'vtalrm' | 'prof' | 'winch' | 'io' | 'pwr' |
'sys' | 'emt' | 'exists' | 'rtmin+0' ... 'rtmin+32'
)

SIGNAL PEER = 'peer' '=' AARE

eg.
signal, # allow all signals
signal send set=(hup, kill) peer=foo,

Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Seth Arnold <seth.arnold@canonical.com>