GNU Linux-libre 6.9.1-gnu
[releases.git] / security / apparmor / 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
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 }