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_ctx and
17 * the aa_task_ctx.label, both of which are required and are not allowed
18 * to be NULL. The aa_task_ctx is not reference counted and is unique
19 * to each cred (which is reference count). The label pointed to by
20 * the task_ctx 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_ctx
34 * @flags: gfp flags for allocation
36 * Returns: allocated buffer or NULL on failure
38 struct aa_task_ctx *aa_alloc_task_context(gfp_t flags)
40 return kzalloc(sizeof(struct aa_task_ctx), flags);
44 * aa_free_task_context - free a task_ctx
45 * @ctx: task_ctx to free (MAYBE NULL)
47 void aa_free_task_context(struct aa_task_ctx *ctx)
50 aa_put_label(ctx->label);
51 aa_put_label(ctx->previous);
52 aa_put_label(ctx->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_ctx *new, const struct aa_task_ctx *old)
66 aa_get_label(new->label);
67 aa_get_label(new->previous);
68 aa_get_label(new->onexec);
72 * aa_get_task_label - Get another task's label
73 * @task: task to query (NOT NULL)
75 * Returns: counted reference to @task's label
77 struct aa_label *aa_get_task_label(struct task_struct *task)
82 p = aa_get_newest_label(__aa_task_raw_label(task));
89 * aa_replace_current_label - replace the current tasks label
90 * @label: new label (NOT NULL)
92 * Returns: 0 or error on failure
94 int aa_replace_current_label(struct aa_label *label)
96 struct aa_task_ctx *ctx = current_ctx();
100 if (ctx->label == label)
103 if (current_cred() != current_real_cred())
106 new = prepare_creds();
111 if (unconfined(label) || (labels_ns(ctx->label) != labels_ns(label)))
112 /* if switching to unconfined or a different label namespace
113 * clear out context state
115 aa_clear_task_ctx_trans(ctx);
118 * be careful switching ctx->profile, when racing replacement it
119 * is possible that ctx->profile->proxy->profile is the reference
120 * keeping @profile valid, so make sure to get its reference before
121 * dropping the reference on ctx->profile
124 aa_put_label(ctx->label);
132 * aa_set_current_onexec - set the tasks change_profile to happen onexec
133 * @label: system label to set at exec (MAYBE NULL to clear value)
134 * @stack: whether stacking should be done
135 * Returns: 0 or error on failure
137 int aa_set_current_onexec(struct aa_label *label, bool stack)
139 struct aa_task_ctx *ctx;
140 struct cred *new = prepare_creds();
146 aa_clear_task_ctx_trans(ctx);
155 * aa_set_current_hat - set the current tasks hat
156 * @label: label to set as the current hat (NOT NULL)
157 * @token: token value that must be specified to change from the hat
159 * Do switch of tasks hat. If the task is currently in a hat
160 * validate the token to match.
162 * Returns: 0 or error on failure
164 int aa_set_current_hat(struct aa_label *label, u64 token)
166 struct aa_task_ctx *ctx;
167 struct cred *new = prepare_creds();
173 if (!ctx->previous) {
174 /* transfer refcount */
175 ctx->previous = ctx->label;
177 } else if (ctx->token == token) {
178 aa_put_label(ctx->label);
180 /* previous_profile && ctx->token != token */
184 ctx->label = aa_get_newest_label(label);
185 /* clear exec on switching context */
186 aa_put_label(ctx->onexec);
194 * aa_restore_previous_label - exit from hat context restoring previous label
195 * @token: the token that must be matched to exit hat context
197 * Attempt to return out of a hat to the previous label. The token
198 * must match the stored token value.
200 * Returns: 0 or error of failure
202 int aa_restore_previous_label(u64 token)
204 struct aa_task_ctx *ctx;
205 struct cred *new = prepare_creds();
210 if (ctx->token != token) {
214 /* ignore restores when there is no saved label */
215 if (!ctx->previous) {
220 aa_put_label(ctx->label);
221 ctx->label = aa_get_newest_label(ctx->previous);
223 /* clear exec && prev information when restoring to previous context */
224 aa_clear_task_ctx_trans(ctx);