Root/security/apparmor/resource.c

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 */
27static 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 */
44static 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 */
67int 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 */
83int 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 */
105void __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

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