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b886d83c | 1 | // SPDX-License-Identifier: GPL-2.0-only |
c75afcd1 JJ |
2 | /* |
3 | * AppArmor security module | |
4 | * | |
de62de59 | 5 | * This file contains AppArmor task related definitions and mediation |
c75afcd1 | 6 | * |
de62de59 | 7 | * Copyright 2017 Canonical Ltd. |
c75afcd1 | 8 | * |
c75afcd1 JJ |
9 | * TODO |
10 | * If a task uses change_hat it currently does not return to the old | |
11 | * cred or task context but instead creates a new one. Ideally the task | |
12 | * should return to the previous cred if it has not been modified. | |
c75afcd1 JJ |
13 | */ |
14 | ||
d8889d49 | 15 | #include "include/cred.h" |
de62de59 | 16 | #include "include/task.h" |
c75afcd1 | 17 | |
3cfcc19e | 18 | /** |
637f688d | 19 | * aa_get_task_label - Get another task's label |
3cfcc19e JJ |
20 | * @task: task to query (NOT NULL) |
21 | * | |
637f688d | 22 | * Returns: counted reference to @task's label |
3cfcc19e | 23 | */ |
637f688d | 24 | struct aa_label *aa_get_task_label(struct task_struct *task) |
3cfcc19e | 25 | { |
637f688d | 26 | struct aa_label *p; |
3cfcc19e JJ |
27 | |
28 | rcu_read_lock(); | |
637f688d | 29 | p = aa_get_newest_label(__aa_task_raw_label(task)); |
3cfcc19e JJ |
30 | rcu_read_unlock(); |
31 | ||
32 | return p; | |
33 | } | |
34 | ||
c75afcd1 | 35 | /** |
637f688d JJ |
36 | * aa_replace_current_label - replace the current tasks label |
37 | * @label: new label (NOT NULL) | |
c75afcd1 JJ |
38 | * |
39 | * Returns: 0 or error on failure | |
40 | */ | |
637f688d | 41 | int aa_replace_current_label(struct aa_label *label) |
c75afcd1 | 42 | { |
d9087c49 | 43 | struct aa_label *old = aa_current_raw_label(); |
9fcf78cc | 44 | struct aa_task_ctx *ctx = task_ctx(current); |
c75afcd1 | 45 | struct cred *new; |
d9087c49 | 46 | |
637f688d | 47 | AA_BUG(!label); |
c75afcd1 | 48 | |
d9087c49 | 49 | if (old == label) |
c75afcd1 JJ |
50 | return 0; |
51 | ||
a20aa95f JJ |
52 | if (current_cred() != current_real_cred()) |
53 | return -EBUSY; | |
54 | ||
c75afcd1 JJ |
55 | new = prepare_creds(); |
56 | if (!new) | |
57 | return -ENOMEM; | |
58 | ||
9fcf78cc JJ |
59 | if (ctx->nnp && label_is_stale(ctx->nnp)) { |
60 | struct aa_label *tmp = ctx->nnp; | |
61 | ||
62 | ctx->nnp = aa_get_newest_label(tmp); | |
63 | aa_put_label(tmp); | |
64 | } | |
d9087c49 JJ |
65 | if (unconfined(label) || (labels_ns(old) != labels_ns(label))) |
66 | /* | |
67 | * if switching to unconfined or a different label namespace | |
c75afcd1 JJ |
68 | * clear out context state |
69 | */ | |
de62de59 | 70 | aa_clear_task_ctx_trans(task_ctx(current)); |
7a2871b5 | 71 | |
55a26ebf | 72 | /* |
d9087c49 JJ |
73 | * be careful switching cred label, when racing replacement it |
74 | * is possible that the cred labels's->proxy->label is the reference | |
75 | * keeping @label valid, so make sure to get its reference before | |
76 | * dropping the reference on the cred's label | |
55a26ebf | 77 | */ |
637f688d | 78 | aa_get_label(label); |
d9087c49 | 79 | aa_put_label(cred_label(new)); |
69b5a44a | 80 | set_cred_label(new, label); |
c75afcd1 JJ |
81 | |
82 | commit_creds(new); | |
83 | return 0; | |
84 | } | |
85 | ||
de62de59 | 86 | |
c75afcd1 JJ |
87 | /** |
88 | * aa_set_current_onexec - set the tasks change_profile to happen onexec | |
637f688d JJ |
89 | * @label: system label to set at exec (MAYBE NULL to clear value) |
90 | * @stack: whether stacking should be done | |
c75afcd1 JJ |
91 | * Returns: 0 or error on failure |
92 | */ | |
637f688d | 93 | int aa_set_current_onexec(struct aa_label *label, bool stack) |
c75afcd1 | 94 | { |
de62de59 | 95 | struct aa_task_ctx *ctx = task_ctx(current); |
c75afcd1 | 96 | |
637f688d | 97 | aa_get_label(label); |
3b529a76 | 98 | aa_put_label(ctx->onexec); |
637f688d JJ |
99 | ctx->onexec = label; |
100 | ctx->token = stack; | |
c75afcd1 | 101 | |
c75afcd1 JJ |
102 | return 0; |
103 | } | |
104 | ||
105 | /** | |
106 | * aa_set_current_hat - set the current tasks hat | |
637f688d | 107 | * @label: label to set as the current hat (NOT NULL) |
c75afcd1 JJ |
108 | * @token: token value that must be specified to change from the hat |
109 | * | |
110 | * Do switch of tasks hat. If the task is currently in a hat | |
111 | * validate the token to match. | |
112 | * | |
113 | * Returns: 0 or error on failure | |
114 | */ | |
637f688d | 115 | int aa_set_current_hat(struct aa_label *label, u64 token) |
c75afcd1 | 116 | { |
de62de59 | 117 | struct aa_task_ctx *ctx = task_ctx(current); |
d9087c49 | 118 | struct cred *new; |
3b529a76 | 119 | |
d9087c49 | 120 | new = prepare_creds(); |
c75afcd1 JJ |
121 | if (!new) |
122 | return -ENOMEM; | |
637f688d | 123 | AA_BUG(!label); |
c75afcd1 | 124 | |
f175221a | 125 | if (!ctx->previous) { |
c75afcd1 | 126 | /* transfer refcount */ |
f175221a JJ |
127 | ctx->previous = cred_label(new); |
128 | ctx->token = token; | |
129 | } else if (ctx->token == token) { | |
d9087c49 | 130 | aa_put_label(cred_label(new)); |
c75afcd1 | 131 | } else { |
55a26ebf | 132 | /* previous_profile && ctx->token != token */ |
c75afcd1 JJ |
133 | abort_creds(new); |
134 | return -EACCES; | |
135 | } | |
3b529a76 | 136 | |
69b5a44a | 137 | set_cred_label(new, aa_get_newest_label(label)); |
c75afcd1 | 138 | /* clear exec on switching context */ |
f175221a JJ |
139 | aa_put_label(ctx->onexec); |
140 | ctx->onexec = NULL; | |
c75afcd1 JJ |
141 | |
142 | commit_creds(new); | |
143 | return 0; | |
144 | } | |
145 | ||
146 | /** | |
637f688d | 147 | * aa_restore_previous_label - exit from hat context restoring previous label |
c75afcd1 JJ |
148 | * @token: the token that must be matched to exit hat context |
149 | * | |
637f688d | 150 | * Attempt to return out of a hat to the previous label. The token |
c75afcd1 JJ |
151 | * must match the stored token value. |
152 | * | |
153 | * Returns: 0 or error of failure | |
154 | */ | |
637f688d | 155 | int aa_restore_previous_label(u64 token) |
c75afcd1 | 156 | { |
de62de59 | 157 | struct aa_task_ctx *ctx = task_ctx(current); |
3b529a76 | 158 | struct cred *new; |
c75afcd1 | 159 | |
f175221a | 160 | if (ctx->token != token) |
c75afcd1 | 161 | return -EACCES; |
637f688d | 162 | /* ignore restores when there is no saved label */ |
f175221a | 163 | if (!ctx->previous) |
c75afcd1 | 164 | return 0; |
3b529a76 JJ |
165 | |
166 | new = prepare_creds(); | |
167 | if (!new) | |
168 | return -ENOMEM; | |
c75afcd1 | 169 | |
d9087c49 | 170 | aa_put_label(cred_label(new)); |
69b5a44a | 171 | set_cred_label(new, aa_get_newest_label(ctx->previous)); |
d9087c49 | 172 | AA_BUG(!cred_label(new)); |
7a2871b5 | 173 | /* clear exec && prev information when restoring to previous context */ |
f175221a | 174 | aa_clear_task_ctx_trans(ctx); |
c75afcd1 JJ |
175 | |
176 | commit_creds(new); | |
3b529a76 | 177 | |
c75afcd1 JJ |
178 | return 0; |
179 | } |