2 * AppArmor security module
4 * This file contains AppArmor functions used to manipulate object security
7 * Copyright (C) 1998-2008 Novell/SUSE
8 * Copyright 2009-2010 Canonical Ltd.
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
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.
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.
29 #include "include/context.h"
30 #include "include/policy.h"
33 * aa_alloc_task_context - allocate a new task_cxt
34 * @flags: gfp flags for allocation
36 * Returns: allocated buffer or NULL on failure
38 struct aa_task_cxt *aa_alloc_task_context(gfp_t flags)
40 return kzalloc(sizeof(struct aa_task_cxt), flags);
44 * aa_free_task_context - free a task_cxt
45 * @cxt: task_cxt to free (MAYBE NULL)
47 void aa_free_task_context(struct aa_task_cxt *cxt)
50 aa_put_profile(cxt->profile);
51 aa_put_profile(cxt->previous);
52 aa_put_profile(cxt->onexec);
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)
63 void aa_dup_task_context(struct aa_task_cxt *new, const struct aa_task_cxt *old)
66 aa_get_profile(new->profile);
67 aa_get_profile(new->previous);
68 aa_get_profile(new->onexec);
72 * aa_replace_current_profile - replace the current tasks profiles
73 * @profile: new profile (NOT NULL)
75 * Returns: 0 or error on failure
77 int aa_replace_current_profile(struct aa_profile *profile)
79 struct aa_task_cxt *cxt = current_cred()->security;
83 if (cxt->profile == profile)
86 new = prepare_creds();
91 if (unconfined(profile) || (cxt->profile->ns != profile->ns)) {
92 /* if switching to unconfined or a different profile namespace
93 * clear out context state
95 aa_put_profile(cxt->previous);
96 aa_put_profile(cxt->onexec);
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;
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)
117 * Returns: 0 or error on failure
119 int aa_set_current_onexec(struct aa_profile *profile)
121 struct aa_task_cxt *cxt;
122 struct cred *new = prepare_creds();
127 aa_get_profile(profile);
128 aa_put_profile(cxt->onexec);
129 cxt->onexec = profile;
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
140 * Do switch of tasks hat. If the task is currently in a hat
141 * validate the token to match.
143 * Returns: 0 or error on failure
145 int aa_set_current_hat(struct aa_profile *profile, u64 token)
147 struct aa_task_cxt *cxt;
148 struct cred *new = prepare_creds();
154 if (!cxt->previous) {
155 /* transfer refcount */
156 cxt->previous = cxt->profile;
158 } else if (cxt->token == token) {
159 aa_put_profile(cxt->profile);
161 /* previous_profile && cxt->token != token */
165 cxt->profile = aa_get_profile(aa_newest_version(profile));
166 /* clear exec on switching context */
167 aa_put_profile(cxt->onexec);
175 * aa_restore_previous_profile - exit from hat context restoring the profile
176 * @token: the token that must be matched to exit hat context
178 * Attempt to return out of a hat to the previous profile. The token
179 * must match the stored token value.
181 * Returns: 0 or error of failure
183 int aa_restore_previous_profile(u64 token)
185 struct aa_task_cxt *cxt;
186 struct cred *new = prepare_creds();
191 if (cxt->token != token) {
195 /* ignore restores when there is no saved profile */
196 if (!cxt->previous) {
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);
208 /* clear exec && prev information when restoring to previous context */
209 cxt->previous = NULL;
211 aa_put_profile(cxt->onexec);