Loading...
1/*
2 * AppArmor security module
3 *
4 * This file contains AppArmor functions used to manipulate object security
5 * contexts.
6 *
7 * Copyright (C) 1998-2008 Novell/SUSE
8 * Copyright 2009-2010 Canonical Ltd.
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License as
12 * published by the Free Software Foundation, version 2 of the
13 * License.
14 *
15 *
16 * AppArmor sets confinement on every task, via the the aa_task_cxt and
17 * the aa_task_cxt.profile, both of which are required and are not allowed
18 * to be NULL. The aa_task_cxt is not reference counted and is unique
19 * to each cred (which is reference count). The profile pointed to by
20 * the task_cxt is reference counted.
21 *
22 * TODO
23 * If a task uses change_hat it currently does not return to the old
24 * cred or task context but instead creates a new one. Ideally the task
25 * should return to the previous cred if it has not been modified.
26 *
27 */
28
29#include "include/context.h"
30#include "include/policy.h"
31
32/**
33 * aa_alloc_task_context - allocate a new task_cxt
34 * @flags: gfp flags for allocation
35 *
36 * Returns: allocated buffer or NULL on failure
37 */
38struct aa_task_cxt *aa_alloc_task_context(gfp_t flags)
39{
40 return kzalloc(sizeof(struct aa_task_cxt), flags);
41}
42
43/**
44 * aa_free_task_context - free a task_cxt
45 * @cxt: task_cxt to free (MAYBE NULL)
46 */
47void aa_free_task_context(struct aa_task_cxt *cxt)
48{
49 if (cxt) {
50 aa_put_profile(cxt->profile);
51 aa_put_profile(cxt->previous);
52 aa_put_profile(cxt->onexec);
53
54 kzfree(cxt);
55 }
56}
57
58/**
59 * aa_dup_task_context - duplicate a task context, incrementing reference counts
60 * @new: a blank task context (NOT NULL)
61 * @old: the task context to copy (NOT NULL)
62 */
63void aa_dup_task_context(struct aa_task_cxt *new, const struct aa_task_cxt *old)
64{
65 *new = *old;
66 aa_get_profile(new->profile);
67 aa_get_profile(new->previous);
68 aa_get_profile(new->onexec);
69}
70
71/**
72 * aa_get_task_profile - Get another task's profile
73 * @task: task to query (NOT NULL)
74 *
75 * Returns: counted reference to @task's profile
76 */
77struct aa_profile *aa_get_task_profile(struct task_struct *task)
78{
79 struct aa_profile *p;
80
81 rcu_read_lock();
82 p = aa_get_profile(__aa_task_profile(task));
83 rcu_read_unlock();
84
85 return p;
86}
87
88/**
89 * aa_replace_current_profile - replace the current tasks profiles
90 * @profile: new profile (NOT NULL)
91 *
92 * Returns: 0 or error on failure
93 */
94int aa_replace_current_profile(struct aa_profile *profile)
95{
96 struct aa_task_cxt *cxt = current_cxt();
97 struct cred *new;
98 BUG_ON(!profile);
99
100 if (cxt->profile == profile)
101 return 0;
102
103 new = prepare_creds();
104 if (!new)
105 return -ENOMEM;
106
107 cxt = cred_cxt(new);
108 if (unconfined(profile) || (cxt->profile->ns != profile->ns))
109 /* if switching to unconfined or a different profile namespace
110 * clear out context state
111 */
112 aa_clear_task_cxt_trans(cxt);
113
114 /* be careful switching cxt->profile, when racing replacement it
115 * is possible that cxt->profile->replacedby->profile is the reference
116 * keeping @profile valid, so make sure to get its reference before
117 * dropping the reference on cxt->profile */
118 aa_get_profile(profile);
119 aa_put_profile(cxt->profile);
120 cxt->profile = profile;
121
122 commit_creds(new);
123 return 0;
124}
125
126/**
127 * aa_set_current_onexec - set the tasks change_profile to happen onexec
128 * @profile: system profile to set at exec (MAYBE NULL to clear value)
129 *
130 * Returns: 0 or error on failure
131 */
132int aa_set_current_onexec(struct aa_profile *profile)
133{
134 struct aa_task_cxt *cxt;
135 struct cred *new = prepare_creds();
136 if (!new)
137 return -ENOMEM;
138
139 cxt = cred_cxt(new);
140 aa_get_profile(profile);
141 aa_put_profile(cxt->onexec);
142 cxt->onexec = profile;
143
144 commit_creds(new);
145 return 0;
146}
147
148/**
149 * aa_set_current_hat - set the current tasks hat
150 * @profile: profile to set as the current hat (NOT NULL)
151 * @token: token value that must be specified to change from the hat
152 *
153 * Do switch of tasks hat. If the task is currently in a hat
154 * validate the token to match.
155 *
156 * Returns: 0 or error on failure
157 */
158int aa_set_current_hat(struct aa_profile *profile, u64 token)
159{
160 struct aa_task_cxt *cxt;
161 struct cred *new = prepare_creds();
162 if (!new)
163 return -ENOMEM;
164 BUG_ON(!profile);
165
166 cxt = cred_cxt(new);
167 if (!cxt->previous) {
168 /* transfer refcount */
169 cxt->previous = cxt->profile;
170 cxt->token = token;
171 } else if (cxt->token == token) {
172 aa_put_profile(cxt->profile);
173 } else {
174 /* previous_profile && cxt->token != token */
175 abort_creds(new);
176 return -EACCES;
177 }
178 cxt->profile = aa_get_newest_profile(profile);
179 /* clear exec on switching context */
180 aa_put_profile(cxt->onexec);
181 cxt->onexec = NULL;
182
183 commit_creds(new);
184 return 0;
185}
186
187/**
188 * aa_restore_previous_profile - exit from hat context restoring the profile
189 * @token: the token that must be matched to exit hat context
190 *
191 * Attempt to return out of a hat to the previous profile. The token
192 * must match the stored token value.
193 *
194 * Returns: 0 or error of failure
195 */
196int aa_restore_previous_profile(u64 token)
197{
198 struct aa_task_cxt *cxt;
199 struct cred *new = prepare_creds();
200 if (!new)
201 return -ENOMEM;
202
203 cxt = cred_cxt(new);
204 if (cxt->token != token) {
205 abort_creds(new);
206 return -EACCES;
207 }
208 /* ignore restores when there is no saved profile */
209 if (!cxt->previous) {
210 abort_creds(new);
211 return 0;
212 }
213
214 aa_put_profile(cxt->profile);
215 cxt->profile = aa_get_newest_profile(cxt->previous);
216 BUG_ON(!cxt->profile);
217 /* clear exec && prev information when restoring to previous context */
218 aa_clear_task_cxt_trans(cxt);
219
220 commit_creds(new);
221 return 0;
222}
1/*
2 * AppArmor security module
3 *
4 * This file contains AppArmor functions used to manipulate object security
5 * contexts.
6 *
7 * Copyright (C) 1998-2008 Novell/SUSE
8 * Copyright 2009-2010 Canonical Ltd.
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License as
12 * published by the Free Software Foundation, version 2 of the
13 * License.
14 *
15 *
16 * AppArmor sets confinement on every task, via the the aa_task_cxt and
17 * the aa_task_cxt.profile, both of which are required and are not allowed
18 * to be NULL. The aa_task_cxt is not reference counted and is unique
19 * to each cred (which is reference count). The profile pointed to by
20 * the task_cxt is reference counted.
21 *
22 * TODO
23 * If a task uses change_hat it currently does not return to the old
24 * cred or task context but instead creates a new one. Ideally the task
25 * should return to the previous cred if it has not been modified.
26 *
27 */
28
29#include "include/context.h"
30#include "include/policy.h"
31
32/**
33 * aa_alloc_task_context - allocate a new task_cxt
34 * @flags: gfp flags for allocation
35 *
36 * Returns: allocated buffer or NULL on failure
37 */
38struct aa_task_cxt *aa_alloc_task_context(gfp_t flags)
39{
40 return kzalloc(sizeof(struct aa_task_cxt), flags);
41}
42
43/**
44 * aa_free_task_context - free a task_cxt
45 * @cxt: task_cxt to free (MAYBE NULL)
46 */
47void aa_free_task_context(struct aa_task_cxt *cxt)
48{
49 if (cxt) {
50 aa_put_profile(cxt->profile);
51 aa_put_profile(cxt->previous);
52 aa_put_profile(cxt->onexec);
53
54 kzfree(cxt);
55 }
56}
57
58/**
59 * aa_dup_task_context - duplicate a task context, incrementing reference counts
60 * @new: a blank task context (NOT NULL)
61 * @old: the task context to copy (NOT NULL)
62 */
63void aa_dup_task_context(struct aa_task_cxt *new, const struct aa_task_cxt *old)
64{
65 *new = *old;
66 aa_get_profile(new->profile);
67 aa_get_profile(new->previous);
68 aa_get_profile(new->onexec);
69}
70
71/**
72 * aa_replace_current_profile - replace the current tasks profiles
73 * @profile: new profile (NOT NULL)
74 *
75 * Returns: 0 or error on failure
76 */
77int aa_replace_current_profile(struct aa_profile *profile)
78{
79 struct aa_task_cxt *cxt = current_cred()->security;
80 struct cred *new;
81 BUG_ON(!profile);
82
83 if (cxt->profile == profile)
84 return 0;
85
86 new = prepare_creds();
87 if (!new)
88 return -ENOMEM;
89
90 cxt = new->security;
91 if (unconfined(profile) || (cxt->profile->ns != profile->ns)) {
92 /* if switching to unconfined or a different profile namespace
93 * clear out context state
94 */
95 aa_put_profile(cxt->previous);
96 aa_put_profile(cxt->onexec);
97 cxt->previous = NULL;
98 cxt->onexec = NULL;
99 cxt->token = 0;
100 }
101 /* be careful switching cxt->profile, when racing replacement it
102 * is possible that cxt->profile->replacedby is the reference keeping
103 * @profile valid, so make sure to get its reference before dropping
104 * the reference on cxt->profile */
105 aa_get_profile(profile);
106 aa_put_profile(cxt->profile);
107 cxt->profile = profile;
108
109 commit_creds(new);
110 return 0;
111}
112
113/**
114 * aa_set_current_onexec - set the tasks change_profile to happen onexec
115 * @profile: system profile to set at exec (MAYBE NULL to clear value)
116 *
117 * Returns: 0 or error on failure
118 */
119int aa_set_current_onexec(struct aa_profile *profile)
120{
121 struct aa_task_cxt *cxt;
122 struct cred *new = prepare_creds();
123 if (!new)
124 return -ENOMEM;
125
126 cxt = new->security;
127 aa_get_profile(profile);
128 aa_put_profile(cxt->onexec);
129 cxt->onexec = profile;
130
131 commit_creds(new);
132 return 0;
133}
134
135/**
136 * aa_set_current_hat - set the current tasks hat
137 * @profile: profile to set as the current hat (NOT NULL)
138 * @token: token value that must be specified to change from the hat
139 *
140 * Do switch of tasks hat. If the task is currently in a hat
141 * validate the token to match.
142 *
143 * Returns: 0 or error on failure
144 */
145int aa_set_current_hat(struct aa_profile *profile, u64 token)
146{
147 struct aa_task_cxt *cxt;
148 struct cred *new = prepare_creds();
149 if (!new)
150 return -ENOMEM;
151 BUG_ON(!profile);
152
153 cxt = new->security;
154 if (!cxt->previous) {
155 /* transfer refcount */
156 cxt->previous = cxt->profile;
157 cxt->token = token;
158 } else if (cxt->token == token) {
159 aa_put_profile(cxt->profile);
160 } else {
161 /* previous_profile && cxt->token != token */
162 abort_creds(new);
163 return -EACCES;
164 }
165 cxt->profile = aa_get_profile(aa_newest_version(profile));
166 /* clear exec on switching context */
167 aa_put_profile(cxt->onexec);
168 cxt->onexec = NULL;
169
170 commit_creds(new);
171 return 0;
172}
173
174/**
175 * aa_restore_previous_profile - exit from hat context restoring the profile
176 * @token: the token that must be matched to exit hat context
177 *
178 * Attempt to return out of a hat to the previous profile. The token
179 * must match the stored token value.
180 *
181 * Returns: 0 or error of failure
182 */
183int aa_restore_previous_profile(u64 token)
184{
185 struct aa_task_cxt *cxt;
186 struct cred *new = prepare_creds();
187 if (!new)
188 return -ENOMEM;
189
190 cxt = new->security;
191 if (cxt->token != token) {
192 abort_creds(new);
193 return -EACCES;
194 }
195 /* ignore restores when there is no saved profile */
196 if (!cxt->previous) {
197 abort_creds(new);
198 return 0;
199 }
200
201 aa_put_profile(cxt->profile);
202 cxt->profile = aa_newest_version(cxt->previous);
203 BUG_ON(!cxt->profile);
204 if (unlikely(cxt->profile != cxt->previous)) {
205 aa_get_profile(cxt->profile);
206 aa_put_profile(cxt->previous);
207 }
208 /* clear exec && prev information when restoring to previous context */
209 cxt->previous = NULL;
210 cxt->token = 0;
211 aa_put_profile(cxt->onexec);
212 cxt->onexec = NULL;
213
214 commit_creds(new);
215 return 0;
216}