xref: /openbmc/linux/security/apparmor/resource.c (revision 690f33e1)
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 	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  */
audit_resource(const struct cred * subj_cred,struct aa_profile * profile,unsigned int resource,unsigned long value,struct aa_label * peer,const char * info,int error)56 static 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  */
aa_map_resource(int resource)83 int aa_map_resource(int resource)
84 {
85 	return rlim_map[resource];
86 }
87 
profile_setrlimit(const struct cred * subj_cred,struct aa_profile * profile,unsigned int resource,struct rlimit * new_rlim)88 static 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 = list_first_entry(&profile->rules,
93 						    typeof(*rules), list);
94 	int e = 0;
95 
96 	if (rules->rlimits.mask & (1 << resource) && new_rlim->rlim_max >
97 	    rules->rlimits.limits[resource].rlim_max)
98 		e = -EACCES;
99 	return audit_resource(subj_cred, profile, resource, new_rlim->rlim_max,
100 			      NULL, NULL, e);
101 }
102 
103 /**
104  * aa_task_setrlimit - test permission to set an rlimit
105  * @subj_cred: cred setting the limit
106  * @label: label confining the task  (NOT NULL)
107  * @task: task the resource is being set on
108  * @resource: the resource being set
109  * @new_rlim: the new resource limit  (NOT NULL)
110  *
111  * Control raising the processes hard limit.
112  *
113  * Returns: 0 or error code if setting resource failed
114  */
aa_task_setrlimit(const struct cred * subj_cred,struct aa_label * label,struct task_struct * task,unsigned int resource,struct rlimit * new_rlim)115 int aa_task_setrlimit(const struct cred *subj_cred, struct aa_label *label,
116 		      struct task_struct *task,
117 		      unsigned int resource, struct rlimit *new_rlim)
118 {
119 	struct aa_profile *profile;
120 	struct aa_label *peer;
121 	int error = 0;
122 
123 	rcu_read_lock();
124 	peer = aa_get_newest_cred_label(__task_cred(task));
125 	rcu_read_unlock();
126 
127 	/* TODO: extend resource control to handle other (non current)
128 	 * profiles.  AppArmor rules currently have the implicit assumption
129 	 * that the task is setting the resource of a task confined with
130 	 * the same profile or that the task setting the resource of another
131 	 * task has CAP_SYS_RESOURCE.
132 	 */
133 
134 	if (label != peer &&
135 	    aa_capable(subj_cred, label, CAP_SYS_RESOURCE, CAP_OPT_NOAUDIT) != 0)
136 		error = fn_for_each(label, profile,
137 				audit_resource(subj_cred, profile, resource,
138 					       new_rlim->rlim_max, peer,
139 					       "cap_sys_resource", -EACCES));
140 	else
141 		error = fn_for_each_confined(label, profile,
142 				profile_setrlimit(subj_cred, profile, resource,
143 						  new_rlim));
144 	aa_put_label(peer);
145 
146 	return error;
147 }
148 
149 /**
150  * __aa_transition_rlimits - apply new profile rlimits
151  * @old_l: old label on task  (NOT NULL)
152  * @new_l: new label with rlimits to apply  (NOT NULL)
153  */
__aa_transition_rlimits(struct aa_label * old_l,struct aa_label * new_l)154 void __aa_transition_rlimits(struct aa_label *old_l, struct aa_label *new_l)
155 {
156 	unsigned int mask = 0;
157 	struct rlimit *rlim, *initrlim;
158 	struct aa_profile *old, *new;
159 	struct label_it i;
160 
161 	old = labels_profile(old_l);
162 	new = labels_profile(new_l);
163 
164 	/* for any rlimits the profile controlled, reset the soft limit
165 	 * to the lesser of the tasks hard limit and the init tasks soft limit
166 	 */
167 	label_for_each_confined(i, old_l, old) {
168 		struct aa_ruleset *rules = list_first_entry(&old->rules,
169 							    typeof(*rules),
170 							    list);
171 		if (rules->rlimits.mask) {
172 			int j;
173 
174 			for (j = 0, mask = 1; j < RLIM_NLIMITS; j++,
175 				     mask <<= 1) {
176 				if (rules->rlimits.mask & mask) {
177 					rlim = current->signal->rlim + j;
178 					initrlim = init_task.signal->rlim + j;
179 					rlim->rlim_cur = min(rlim->rlim_max,
180 							    initrlim->rlim_cur);
181 				}
182 			}
183 		}
184 	}
185 
186 	/* set any new hard limits as dictated by the new profile */
187 	label_for_each_confined(i, new_l, new) {
188 		struct aa_ruleset *rules = list_first_entry(&new->rules,
189 							    typeof(*rules),
190 							    list);
191 		int j;
192 
193 		if (!rules->rlimits.mask)
194 			continue;
195 		for (j = 0, mask = 1; j < RLIM_NLIMITS; j++, mask <<= 1) {
196 			if (!(rules->rlimits.mask & mask))
197 				continue;
198 
199 			rlim = current->signal->rlim + j;
200 			rlim->rlim_max = min(rlim->rlim_max,
201 					     rules->rlimits.limits[j].rlim_max);
202 			/* soft limit should not exceed hard limit */
203 			rlim->rlim_cur = min(rlim->rlim_cur, rlim->rlim_max);
204 		}
205 	}
206 }
207