1 /*
2  * AppArmor security module
3  *
4  * This file contains AppArmor resource mediation and attachment
5  *
6  * Copyright (C) 1998-2008 Novell/SUSE
7  * Copyright 2009-2010 Canonical Ltd.
8  *
9  * This program is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU General Public License as
11  * published by the Free Software Foundation, version 2 of the
12  * License.
13  */
14 
15 #include <linux/audit.h>
16 
17 #include "include/audit.h"
18 #include "include/resource.h"
19 #include "include/policy.h"
20 
21 /*
22  * Table of rlimit names: we generate it from resource.h.
23  */
24 #include "rlim_names.h"
25 
26 /* audit callback for resource specific fields */
audit_cb(struct audit_buffer * ab,void * va)27 static void audit_cb(struct audit_buffer *ab, void *va)
28 {
29 	struct common_audit_data *sa = va;
30 
31 	audit_log_format(ab, " rlimit=%s value=%lu",
32 			 rlim_names[sa->aad.rlim.rlim], sa->aad.rlim.max);
33 }
34 
35 /**
36  * audit_resource - audit setting resource limit
37  * @profile: profile being enforced  (NOT NULL)
38  * @resoure: rlimit being auditing
39  * @value: value being set
40  * @error: error value
41  *
42  * Returns: 0 or sa->error else other error code on failure
43  */
audit_resource(struct aa_profile * profile,unsigned int resource,unsigned long value,int error)44 static int audit_resource(struct aa_profile *profile, unsigned int resource,
45 			  unsigned long value, int error)
46 {
47 	struct common_audit_data sa;
48 
49 	COMMON_AUDIT_DATA_INIT(&sa, NONE);
50 	sa.aad.op = OP_SETRLIMIT,
51 	sa.aad.rlim.rlim = resource;
52 	sa.aad.rlim.max = value;
53 	sa.aad.error = error;
54 	return aa_audit(AUDIT_APPARMOR_AUTO, profile, GFP_KERNEL, &sa,
55 			audit_cb);
56 }
57 
58 /**
59  * aa_map_resouce - map compiled policy resource to internal #
60  * @resource: flattened policy resource number
61  *
62  * Returns: resource # for the current architecture.
63  *
64  * rlimit resource can vary based on architecture, map the compiled policy
65  * resource # to the internal representation for the architecture.
66  */
aa_map_resource(int resource)67 int aa_map_resource(int resource)
68 {
69 	return rlim_map[resource];
70 }
71 
72 /**
73  * aa_task_setrlimit - test permission to set an rlimit
74  * @profile - profile confining the task  (NOT NULL)
75  * @task - task the resource is being set on
76  * @resource - the resource being set
77  * @new_rlim - the new resource limit  (NOT NULL)
78  *
79  * Control raising the processes hard limit.
80  *
81  * Returns: 0 or error code if setting resource failed
82  */
aa_task_setrlimit(struct aa_profile * profile,struct task_struct * task,unsigned int resource,struct rlimit * new_rlim)83 int aa_task_setrlimit(struct aa_profile *profile, struct task_struct *task,
84 		      unsigned int resource, struct rlimit *new_rlim)
85 {
86 	int error = 0;
87 
88 	/* TODO: extend resource control to handle other (non current)
89 	 * processes.  AppArmor rules currently have the implicit assumption
90 	 * that the task is setting the resource of the current process
91 	 */
92 	if ((task != current->group_leader) ||
93 	    (profile->rlimits.mask & (1 << resource) &&
94 	     new_rlim->rlim_max > profile->rlimits.limits[resource].rlim_max))
95 		error = -EACCES;
96 
97 	return audit_resource(profile, resource, new_rlim->rlim_max, error);
98 }
99 
100 /**
101  * __aa_transition_rlimits - apply new profile rlimits
102  * @old: old profile on task  (NOT NULL)
103  * @new: new profile with rlimits to apply  (NOT NULL)
104  */
__aa_transition_rlimits(struct aa_profile * old,struct aa_profile * new)105 void __aa_transition_rlimits(struct aa_profile *old, struct aa_profile *new)
106 {
107 	unsigned int mask = 0;
108 	struct rlimit *rlim, *initrlim;
109 	int i;
110 
111 	/* for any rlimits the profile controlled reset the soft limit
112 	 * to the less of the tasks hard limit and the init tasks soft limit
113 	 */
114 	if (old->rlimits.mask) {
115 		for (i = 0, mask = 1; i < RLIM_NLIMITS; i++, mask <<= 1) {
116 			if (old->rlimits.mask & mask) {
117 				rlim = current->signal->rlim + i;
118 				initrlim = init_task.signal->rlim + i;
119 				rlim->rlim_cur = min(rlim->rlim_max,
120 						     initrlim->rlim_cur);
121 			}
122 		}
123 	}
124 
125 	/* set any new hard limits as dictated by the new profile */
126 	if (!new->rlimits.mask)
127 		return;
128 	for (i = 0, mask = 1; i < RLIM_NLIMITS; i++, mask <<= 1) {
129 		if (!(new->rlimits.mask & mask))
130 			continue;
131 
132 		rlim = current->signal->rlim + i;
133 		rlim->rlim_max = min(rlim->rlim_max,
134 				     new->rlimits.limits[i].rlim_max);
135 		/* soft limit should not exceed hard limit */
136 		rlim->rlim_cur = min(rlim->rlim_cur, rlim->rlim_max);
137 	}
138 }
139