/* * AppArmor security module * * This file contains AppArmor task related definitions and mediation * * Copyright 2017 Canonical Ltd. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation, version 2 of the * License. * * 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;}