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