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 */
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 */
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 */
83 int aa_map_resource(int resource)
84 {
85 return rlim_map[resource];
86 }
87
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 */
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 */
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
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