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