![John Johansen](/assets/img/avatar_default.png)
This came in yesterday, and I have verified our regression tests
were missing this and it can cause an oops. Please apply.
There is a an off-by-one comparision on sig against MAXMAPPED_SIG
that can lead to a read outside the sig_map array if sig
is MAXMAPPED_SIG. Fix this.
Verified that the check is an out of bounds case that can cause an oops.
Revised: add comparison fix to second case
Fixes: cd1dbf76b2
("apparmor: add the ability to mediate signals")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
223 lines
6.2 KiB
C
223 lines
6.2 KiB
C
/*
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* AppArmor security module
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*
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* This file contains AppArmor ipc mediation
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*
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* Copyright (C) 1998-2008 Novell/SUSE
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* Copyright 2009-2017 Canonical Ltd.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, version 2 of the
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* License.
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*/
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#include <linux/gfp.h>
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#include <linux/ptrace.h>
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#include "include/audit.h"
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#include "include/capability.h"
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#include "include/context.h"
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#include "include/policy.h"
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#include "include/ipc.h"
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#include "include/sig_names.h"
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/**
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* audit_ptrace_mask - convert mask to permission string
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* @buffer: buffer to write string to (NOT NULL)
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* @mask: permission mask to convert
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*/
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static void audit_ptrace_mask(struct audit_buffer *ab, u32 mask)
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{
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switch (mask) {
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case MAY_READ:
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audit_log_string(ab, "read");
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break;
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case MAY_WRITE:
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audit_log_string(ab, "trace");
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break;
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case AA_MAY_BE_READ:
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audit_log_string(ab, "readby");
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break;
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case AA_MAY_BE_TRACED:
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audit_log_string(ab, "tracedby");
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break;
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}
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}
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/* call back to audit ptrace fields */
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static void audit_ptrace_cb(struct audit_buffer *ab, void *va)
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{
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struct common_audit_data *sa = va;
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if (aad(sa)->request & AA_PTRACE_PERM_MASK) {
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audit_log_format(ab, " requested_mask=");
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audit_ptrace_mask(ab, aad(sa)->request);
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if (aad(sa)->denied & AA_PTRACE_PERM_MASK) {
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audit_log_format(ab, " denied_mask=");
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audit_ptrace_mask(ab, aad(sa)->denied);
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}
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}
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audit_log_format(ab, " peer=");
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aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
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FLAGS_NONE, GFP_ATOMIC);
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}
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/* TODO: conditionals */
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static int profile_ptrace_perm(struct aa_profile *profile,
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struct aa_profile *peer, u32 request,
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struct common_audit_data *sa)
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{
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struct aa_perms perms = { };
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/* need because of peer in cross check */
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if (profile_unconfined(profile) ||
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!PROFILE_MEDIATES(profile, AA_CLASS_PTRACE))
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return 0;
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aad(sa)->peer = &peer->label;
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aa_profile_match_label(profile, &peer->label, AA_CLASS_PTRACE, request,
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&perms);
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aa_apply_modes_to_perms(profile, &perms);
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return aa_check_perms(profile, &perms, request, sa, audit_ptrace_cb);
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}
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static int cross_ptrace_perm(struct aa_profile *tracer,
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struct aa_profile *tracee, u32 request,
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struct common_audit_data *sa)
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{
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if (PROFILE_MEDIATES(tracer, AA_CLASS_PTRACE))
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return xcheck(profile_ptrace_perm(tracer, tracee, request, sa),
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profile_ptrace_perm(tracee, tracer,
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request << PTRACE_PERM_SHIFT,
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sa));
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/* policy uses the old style capability check for ptrace */
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if (profile_unconfined(tracer) || tracer == tracee)
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return 0;
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aad(sa)->label = &tracer->label;
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aad(sa)->peer = &tracee->label;
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aad(sa)->request = 0;
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aad(sa)->error = aa_capable(&tracer->label, CAP_SYS_PTRACE, 1);
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return aa_audit(AUDIT_APPARMOR_AUTO, tracer, sa, audit_ptrace_cb);
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}
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/**
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* aa_may_ptrace - test if tracer task can trace the tracee
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* @tracer: label of the task doing the tracing (NOT NULL)
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* @tracee: task label to be traced
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* @request: permission request
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*
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* Returns: %0 else error code if permission denied or error
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*/
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int aa_may_ptrace(struct aa_label *tracer, struct aa_label *tracee,
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u32 request)
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{
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DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_PTRACE);
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return xcheck_labels_profiles(tracer, tracee, cross_ptrace_perm,
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request, &sa);
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}
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static inline int map_signal_num(int sig)
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{
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if (sig > SIGRTMAX)
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return SIGUNKNOWN;
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else if (sig >= SIGRTMIN)
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return sig - SIGRTMIN + 128; /* rt sigs mapped to 128 */
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else if (sig < MAXMAPPED_SIG)
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return sig_map[sig];
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return SIGUNKNOWN;
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}
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/**
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* audit_file_mask - convert mask to permission string
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* @buffer: buffer to write string to (NOT NULL)
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* @mask: permission mask to convert
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*/
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static void audit_signal_mask(struct audit_buffer *ab, u32 mask)
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{
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if (mask & MAY_READ)
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audit_log_string(ab, "receive");
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if (mask & MAY_WRITE)
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audit_log_string(ab, "send");
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}
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/**
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* audit_cb - call back for signal specific audit fields
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* @ab: audit_buffer (NOT NULL)
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* @va: audit struct to audit values of (NOT NULL)
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*/
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static void audit_signal_cb(struct audit_buffer *ab, void *va)
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{
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struct common_audit_data *sa = va;
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if (aad(sa)->request & AA_SIGNAL_PERM_MASK) {
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audit_log_format(ab, " requested_mask=");
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audit_signal_mask(ab, aad(sa)->request);
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if (aad(sa)->denied & AA_SIGNAL_PERM_MASK) {
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audit_log_format(ab, " denied_mask=");
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audit_signal_mask(ab, aad(sa)->denied);
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}
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}
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if (aad(sa)->signal < MAXMAPPED_SIG)
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audit_log_format(ab, " signal=%s", sig_names[aad(sa)->signal]);
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else
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audit_log_format(ab, " signal=rtmin+%d",
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aad(sa)->signal - 128);
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audit_log_format(ab, " peer=");
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aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
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FLAGS_NONE, GFP_ATOMIC);
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}
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/* TODO: update to handle compound name&name2, conditionals */
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static void profile_match_signal(struct aa_profile *profile, const char *label,
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int signal, struct aa_perms *perms)
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{
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unsigned int state;
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/* TODO: secondary cache check <profile, profile, perm> */
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state = aa_dfa_next(profile->policy.dfa,
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profile->policy.start[AA_CLASS_SIGNAL],
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signal);
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state = aa_dfa_match(profile->policy.dfa, state, label);
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aa_compute_perms(profile->policy.dfa, state, perms);
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}
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static int profile_signal_perm(struct aa_profile *profile,
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struct aa_profile *peer, u32 request,
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struct common_audit_data *sa)
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{
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struct aa_perms perms;
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if (profile_unconfined(profile) ||
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!PROFILE_MEDIATES(profile, AA_CLASS_SIGNAL))
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return 0;
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aad(sa)->peer = &peer->label;
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profile_match_signal(profile, peer->base.hname, aad(sa)->signal,
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&perms);
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aa_apply_modes_to_perms(profile, &perms);
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return aa_check_perms(profile, &perms, request, sa, audit_signal_cb);
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}
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static int aa_signal_cross_perm(struct aa_profile *sender,
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struct aa_profile *target,
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struct common_audit_data *sa)
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{
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return xcheck(profile_signal_perm(sender, target, MAY_WRITE, sa),
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profile_signal_perm(target, sender, MAY_READ, sa));
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}
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int aa_may_signal(struct aa_label *sender, struct aa_label *target, int sig)
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{
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DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_SIGNAL);
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aad(&sa)->signal = map_signal_num(sig);
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return xcheck_labels_profiles(sender, target, aa_signal_cross_perm,
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&sa);
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}
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