/* * AppArmor security module * * This file contains AppArmor functions used to manipulate object security * contexts. * * Copyright (C) 1998-2008 Novell/SUSE * Copyright 2009-2010 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. * * * AppArmor sets confinement on every task, via the the aa_task_ctx and * the aa_task_ctx.label, both of which are required and are not allowed * to be NULL.  The aa_task_ctx is not reference counted and is unique * to each cred (which is reference count).  The label pointed to by * the task_ctx is reference counted. * * 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/context.h"#include "include/policy.h" /** * aa_alloc_task_context - allocate a new task_ctx * @flags: gfp flags for allocation * * Returns: allocated buffer or NULL on failure */struct aa_task_ctx *aa_alloc_task_context(gfp_t flags){	return kzalloc(sizeof(struct aa_task_ctx), flags);} /** * aa_free_task_context - free a task_ctx * @ctx: task_ctx to free (MAYBE NULL) */void aa_free_task_context(struct aa_task_ctx *ctx){	if (ctx) {		aa_put_label(ctx->label);		aa_put_label(ctx->previous);		aa_put_label(ctx->onexec); 		kzfree(ctx);	}} /** * aa_dup_task_context - duplicate a task context, incrementing reference counts * @new: a blank task context      (NOT NULL) * @old: the task context to copy  (NOT NULL) */void aa_dup_task_context(struct aa_task_ctx *new, const struct aa_task_ctx *old){	*new = *old;	aa_get_label(new->label);	aa_get_label(new->previous);	aa_get_label(new->onexec);} /** * 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_task_ctx *ctx = current_ctx();	struct cred *new;	AA_BUG(!label); 	if (ctx->label == label)		return 0; 	if (current_cred() != current_real_cred())		return -EBUSY; 	new  = prepare_creds();	if (!new)		return -ENOMEM; 	ctx = cred_ctx(new);	if (unconfined(label) || (labels_ns(ctx->label) != labels_ns(label)))		/* if switching to unconfined or a different label namespace		 * clear out context state		 */		aa_clear_task_ctx_trans(ctx); 	/*	 * be careful switching ctx->profile, when racing replacement it	 * is possible that ctx->profile->proxy->profile is the reference	 * keeping @profile valid, so make sure to get its reference before	 * dropping the reference on ctx->profile	 */	aa_get_label(label);	aa_put_label(ctx->label);	ctx->label = 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;	struct cred *new = prepare_creds();	if (!new)		return -ENOMEM; 	ctx = cred_ctx(new);	aa_get_label(label);	aa_clear_task_ctx_trans(ctx);	ctx->onexec = label;	ctx->token = stack; 	commit_creds(new);	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;	struct cred *new = prepare_creds();	if (!new)		return -ENOMEM;	AA_BUG(!label); 	ctx = cred_ctx(new);	if (!ctx->previous) {		/* transfer refcount */		ctx->previous = ctx->label;		ctx->token = token;	} else if (ctx->token == token) {		aa_put_label(ctx->label);	} else {		/* previous_profile && ctx->token != token */		abort_creds(new);		return -EACCES;	}	ctx->label = 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;	struct cred *new = prepare_creds();	if (!new)		return -ENOMEM; 	ctx = cred_ctx(new);	if (ctx->token != token) {		abort_creds(new);		return -EACCES;	}	/* ignore restores when there is no saved label */	if (!ctx->previous) {		abort_creds(new);		return 0;	} 	aa_put_label(ctx->label);	ctx->label = aa_get_newest_label(ctx->previous);	AA_BUG(!ctx->label);	/* clear exec && prev information when restoring to previous context */	aa_clear_task_ctx_trans(ctx); 	commit_creds(new);	return 0;}