mirror_ubuntu-kernels/security/apparmor/ipc.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * AppArmor security module
 *
 * This file contains AppArmor ipc mediation
 *
 * Copyright (C) 1998-2008 Novell/SUSE
 * Copyright 2009-2017 Canonical Ltd.
 */

#include <linux/gfp.h>
#include <linux/nsproxy.h>
#include <linux/ipc_namespace.h>

#include "include/audit.h"
#include "include/capability.h"
#include "include/cred.h"
#include "include/path.h"
#include "include/policy.h"
#include "include/ipc.h"
#include "include/sig_names.h"


static inline int map_signal_num(int sig)
{
	if (sig > SIGRTMAX)
		return SIGUNKNOWN;
	else if (sig >= SIGRTMIN)
		return sig - SIGRTMIN + SIGRT_BASE;
	else if (sig < MAXMAPPED_SIG)
		return sig_map[sig];
	return SIGUNKNOWN;
}

/**
 * audit_signal_mask - convert mask to permission string
 * @mask: permission mask to convert
 *
 * Returns: pointer to static string
 */
static const char *audit_signal_mask(u32 mask)
{
	if (mask & MAY_READ)
		return "receive";
	if (mask & MAY_WRITE)
		return "send";
	return "";
}

/**
 * audit_signal_cb() - call back for signal specific audit fields
 * @ab: audit_buffer  (NOT NULL)
 * @va: audit struct to audit values of  (NOT NULL)
 */
static void audit_signal_cb(struct audit_buffer *ab, void *va)
{
	struct common_audit_data *sa = va;
	struct apparmor_audit_data *ad = aad(sa);

	if (ad->request & AA_SIGNAL_PERM_MASK) {
		audit_log_format(ab, " requested_mask=\"%s\"",
				 audit_signal_mask(ad->request));
		if (ad->denied & AA_SIGNAL_PERM_MASK) {
			audit_log_format(ab, " denied_mask=\"%s\"",
					 audit_signal_mask(ad->denied));
		}
	}
	if (ad->signal == SIGUNKNOWN)
		audit_log_format(ab, "signal=unknown(%d)",
				 ad->unmappedsig);
	else if (ad->signal < MAXMAPPED_SIGNAME)
		audit_log_format(ab, " signal=%s", sig_names[ad->signal]);
	else
		audit_log_format(ab, " signal=rtmin+%d",
				 ad->signal - SIGRT_BASE);
	audit_log_format(ab, " peer=");
	aa_label_xaudit(ab, labels_ns(ad->subj_label), ad->peer,
			FLAGS_NONE, GFP_ATOMIC);
}

static int profile_signal_perm(const struct cred *cred,
			       struct aa_profile *profile,
			       struct aa_label *peer, u32 request,
			       struct apparmor_audit_data *ad)
{
	struct aa_ruleset *rules = list_first_entry(&profile->rules,
						    typeof(*rules), list);
	struct aa_perms perms;
	aa_state_t state;

	if (!profile_mediates(profile, AA_CLASS_SIGNAL))
		return 0;

	ad->subj_cred = cred;
	ad->peer = peer;
	/* TODO: secondary cache check <profile, profile, perm> */
	state = RULE_MEDIATES(rules, AA_CLASS_SIGNAL);
	if (!state)
		return 0;
	state = aa_dfa_next(rules->policy->dfa, state, ad->signal);
	aa_label_match(profile, rules, peer, state, false, request, &perms);
	aa_apply_modes_to_perms(profile, &perms);
	return aa_check_perms(profile, &perms, request, ad, audit_signal_cb);
}

int aa_may_signal(const struct cred *subj_cred, struct aa_label *sender,
		  const struct cred *target_cred, struct aa_label *target,
		  int sig)
{
	struct aa_profile *profile;
	DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_NONE, AA_CLASS_SIGNAL, OP_SIGNAL);

	ad.signal = map_signal_num(sig);
	ad.unmappedsig = sig;
	return xcheck_labels(sender, target, profile,
			     profile_signal_perm(subj_cred, profile, target,
						 MAY_WRITE, &ad),
			     profile_signal_perm(target_cred, profile, sender,
						 MAY_READ, &ad));
}


static void audit_mqueue_cb(struct audit_buffer *ab, void *va)
{
	struct apparmor_audit_data *ad = aad_of_va(va);

	aa_audit_perms(ab, ad, NULL, 0, NULL, AA_AUDIT_POSIX_MQUEUE_MASK);

	/* move class into generic audit framse work */
	audit_log_format(ab, "class=\"posix_mqueue\"");
	if (ad->request & AA_AUDIT_FILE_MASK) {
		audit_log_format(ab, " fsuid=%u",
				 from_kuid(&init_user_ns, ad->subj_cred->fsuid));
		audit_log_format(ab, " ouid=%u",
				 from_kuid(&init_user_ns, ad->mq.ouid));
	}
	if (ad->peer) {
		audit_log_format(ab, " olabel=");
		aa_label_xaudit(ab, labels_ns(ad->subj_label), ad->peer,
				FLAGS_NONE, GFP_ATOMIC);
	}
}

int aa_profile_mqueue_perm(struct aa_profile *profile, const struct path *path,
			   u32 request, char *buffer,
			   struct apparmor_audit_data *ad)
{
	struct aa_ruleset *rules = list_first_entry(&profile->rules,
						    typeof(*rules), list);
	struct aa_perms perms = { };
	unsigned int state;
	char *name;

	if (profile_unconfined(profile) ||
	    !RULE_MEDIATES(rules, AA_CLASS_POSIX_MQUEUE))
		return 0;

	ad->subj_label = &profile->label;

	name = dentry_path_raw(path->dentry, buffer, aa_g_path_max);
	if (IS_ERR(name))
		return PTR_ERR(name);
	if (path->mnt != current->nsproxy->ipc_ns->mq_mnt) {
		/* TODO: disconnected path detection */
		pr_warn("apparmor mqueue disconnected TODO\n");
	}

	ad->name = name;

	state = aa_dfa_match(rules->policy->dfa,
			     rules->policy->start[AA_CLASS_POSIX_MQUEUE],
			     name);
	perms = *aa_lookup_perms(rules->policy, state);
	aa_apply_modes_to_perms(profile, &perms);
	if (!denied_perms(&perms, request)) {
		/* early bailout sufficient perms no need to do further
		 * checks
		 */
		return aa_check_perms(profile, &perms, request, ad,
				      audit_mqueue_cb);
	}
	/* continue check to see if we have label perms */
	//aa_label_match(profile, peer??, state false, request, &perms);
	//aa_apply_modes_to_perms(profile, &perms);

	// this will just cause failure without above label check
	return aa_check_perms(profile, &perms, request, ad, audit_mqueue_cb);
}

/* mqueue - no label caching test */
int aa_mqueue_perm(const char *op, const struct cred *subj_cred,
		   struct aa_label *label,
		   const struct path *path, u32 request)
{
	struct aa_profile *profile;
	char *buffer;
	int error;
	DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_NONE, AA_CLASS_POSIX_MQUEUE, op);

	// do we need delegate deleted with mqueues? probably
	//flags |= PATH_DELEGATE_DELETED;

	/* sadly due to rcu walk hairiness, we use dentry_path_raw instead
	 *  of just accessing the name directly, which means we need to
	 *  do the whole buffer allocation mess
	 */
	buffer = aa_get_buffer(false);
	if (!buffer)
		return -ENOMEM;

	/* audit fields that won't change during iteration */
	ad.subj_cred = subj_cred;
	ad.request = request;
	ad.peer = NULL;
	ad.mq.ouid = d_backing_inode(path->dentry) ?
				d_backing_inode(path->dentry)->i_uid :
				subj_cred->fsuid;

	error = fn_for_each_confined(label, profile,
			aa_profile_mqueue_perm(profile, path, request,
					       buffer, &ad));
	aa_put_buffer(buffer);

	return error;
}