resource.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * AppArmor security module
  4 *
  5 * This file contains AppArmor resource mediation and attachment
  6 *
  7 * Copyright (C) 1998-2008 Novell/SUSE
  8 * Copyright 2009-2010 Canonical Ltd.
  9 */
 10
 11#include <linux/audit.h>
 12#include <linux/security.h>
 13
 14#include "include/audit.h"
 15#include "include/cred.h"
 16#include "include/resource.h"
 17#include "include/policy.h"
 18
 19/*
 20 * Table of rlimit names: we generate it from resource.h.
 21 */
 22#include "rlim_names.h"
 23
 24struct aa_sfs_entry aa_sfs_entry_rlimit[] = {
 25	AA_SFS_FILE_STRING("mask", AA_SFS_RLIMIT_MASK),
 26	{ }
 27};
 28
 29/* audit callback for resource specific fields */
 30static void audit_cb(struct audit_buffer *ab, void *va)
 31{
 32	struct common_audit_data *sa = va;
 33	struct apparmor_audit_data *ad = aad(sa);
 34
 35	audit_log_format(ab, " rlimit=%s value=%lu",
 36			 rlim_names[ad->rlim.rlim], ad->rlim.max);
 37	if (ad->peer) {
 38		audit_log_format(ab, " peer=");
 39		aa_label_xaudit(ab, labels_ns(ad->subj_label), ad->peer,
 40				FLAGS_NONE, GFP_ATOMIC);
 41	}
 42}
 43
 44/**
 45 * audit_resource - audit setting resource limit
 46 * @subj_cred: cred setting the resource
 47 * @profile: profile being enforced  (NOT NULL)
 48 * @resource: rlimit being auditing
 49 * @value: value being set
 50 * @peer: aa_albel of the task being set
 51 * @info: info being auditing
 52 * @error: error value
 53 *
 54 * Returns: 0 or ad->error else other error code on failure
 55 */
 56static int audit_resource(const struct cred *subj_cred,
 57			  struct aa_profile *profile, unsigned int resource,
 58			  unsigned long value, struct aa_label *peer,
 59			  const char *info, int error)
 60{
 61	DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_NONE, AA_CLASS_RLIMITS,
 62			  OP_SETRLIMIT);
 63
 64	ad.subj_cred = subj_cred;
 65	ad.rlim.rlim = resource;
 66	ad.rlim.max = value;
 67	ad.peer = peer;
 68	ad.info = info;
 69	ad.error = error;
 70
 71	return aa_audit(AUDIT_APPARMOR_AUTO, profile, &ad, audit_cb);
 72}
 73
 74/**
 75 * aa_map_resource - map compiled policy resource to internal #
 76 * @resource: flattened policy resource number
 77 *
 78 * Returns: resource # for the current architecture.
 79 *
 80 * rlimit resource can vary based on architecture, map the compiled policy
 81 * resource # to the internal representation for the architecture.
 82 */
 83int aa_map_resource(int resource)
 84{
 85	return rlim_map[resource];
 86}
 87
 88static int profile_setrlimit(const struct cred *subj_cred,
 89			     struct aa_profile *profile, unsigned int resource,
 90			     struct rlimit *new_rlim)
 91{
 92	struct aa_ruleset *rules = profile->label.rules[0];
 93	int e = 0;
 94
 95	if (rules->rlimits.mask & (1 << resource) && new_rlim->rlim_max >
 96	    rules->rlimits.limits[resource].rlim_max)
 97		e = -EACCES;
 98	return audit_resource(subj_cred, profile, resource, new_rlim->rlim_max,
 99			      NULL, NULL, e);
100}
101
102/**
103 * aa_task_setrlimit - test permission to set an rlimit
104 * @subj_cred: cred setting the limit
105 * @label: label confining the task  (NOT NULL)
106 * @task: task the resource is being set on
107 * @resource: the resource being set
108 * @new_rlim: the new resource limit  (NOT NULL)
109 *
110 * Control raising the processes hard limit.
111 *
112 * Returns: 0 or error code if setting resource failed
113 */
114int aa_task_setrlimit(const struct cred *subj_cred, struct aa_label *label,
115		      struct task_struct *task,
116		      unsigned int resource, struct rlimit *new_rlim)
117{
118	struct aa_profile *profile;
119	struct aa_label *peer;
120	int error = 0;
121
122	rcu_read_lock();
123	peer = aa_get_newest_cred_label(__task_cred(task));
124	rcu_read_unlock();
125
126	/* TODO: extend resource control to handle other (non current)
127	 * profiles.  AppArmor rules currently have the implicit assumption
128	 * that the task is setting the resource of a task confined with
129	 * the same profile or that the task setting the resource of another
130	 * task has CAP_SYS_RESOURCE.
131	 */
132
133	if (label != peer &&
134	    aa_capable(subj_cred, label, CAP_SYS_RESOURCE, CAP_OPT_NOAUDIT) != 0)
135		error = fn_for_each(label, profile,
136				audit_resource(subj_cred, profile, resource,
137					       new_rlim->rlim_max, peer,
138					       "cap_sys_resource", -EACCES));
139	else
140		error = fn_for_each_confined(label, profile,
141				profile_setrlimit(subj_cred, profile, resource,
142						  new_rlim));
143	aa_put_label(peer);
144
145	return error;
146}
147
148/**
149 * __aa_transition_rlimits - apply new profile rlimits
150 * @old_l: old label on task  (NOT NULL)
151 * @new_l: new label with rlimits to apply  (NOT NULL)
152 */
153void __aa_transition_rlimits(struct aa_label *old_l, struct aa_label *new_l)
154{
155	unsigned int mask = 0;
156	struct rlimit *rlim, *initrlim;
157	struct aa_profile *old, *new;
158	struct label_it i;
159
160	old = labels_profile(old_l);
161	new = labels_profile(new_l);
162
163	/* for any rlimits the profile controlled, reset the soft limit
164	 * to the lesser of the tasks hard limit and the init tasks soft limit
165	 */
166	label_for_each_confined(i, old_l, old) {
167		struct aa_ruleset *rules = old->label.rules[0];
168		if (rules->rlimits.mask) {
169			int j;
170
171			for (j = 0, mask = 1; j < RLIM_NLIMITS; j++,
172				     mask <<= 1) {
173				if (rules->rlimits.mask & mask) {
174					rlim = current->signal->rlim + j;
175					initrlim = init_task.signal->rlim + j;
176					rlim->rlim_cur = min(rlim->rlim_max,
177							    initrlim->rlim_cur);
178				}
179			}
180		}
181	}
182
183	/* set any new hard limits as dictated by the new profile */
184	label_for_each_confined(i, new_l, new) {
185		struct aa_ruleset *rules = new->label.rules[0];
186		int j;
187
188		if (!rules->rlimits.mask)
189			continue;
190		for (j = 0, mask = 1; j < RLIM_NLIMITS; j++, mask <<= 1) {
191			if (!(rules->rlimits.mask & mask))
192				continue;
193
194			rlim = current->signal->rlim + j;
195			rlim->rlim_max = min(rlim->rlim_max,
196					     rules->rlimits.limits[j].rlim_max);
197			/* soft limit should not exceed hard limit */
198			rlim->rlim_cur = min(rlim->rlim_cur, rlim->rlim_max);
199			if (j == RLIMIT_CPU &&
200			    rlim->rlim_cur != RLIM_INFINITY &&
201			    IS_ENABLED(CONFIG_POSIX_TIMERS))
202				(void) update_rlimit_cpu(current->group_leader,
203							 rlim->rlim_cur);
204		}
205	}
206}