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