/* * 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_cxt and * the aa_task_cxt.profile, both of which are required and are not allowed * to be NULL.  The aa_task_cxt is not reference counted and is unique * to each cred (which is reference count).  The profile pointed to by * the task_cxt 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_cxt * @flags: gfp flags for allocation * * Returns: allocated buffer or NULL on failure */struct aa_task_cxt *aa_alloc_task_context(gfp_t flags){	return kzalloc(sizeof(struct aa_task_cxt), flags);} /** * aa_free_task_context - free a task_cxt * @cxt: task_cxt to free (MAYBE NULL) */void aa_free_task_context(struct aa_task_cxt *cxt){	if (cxt) {		aa_put_profile(cxt->profile);		aa_put_profile(cxt->previous);		aa_put_profile(cxt->onexec); 		kzfree(cxt);	}} /** * 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_cxt *new, const struct aa_task_cxt *old){	*new = *old;	aa_get_profile(new->profile);	aa_get_profile(new->previous);	aa_get_profile(new->onexec);} /** * aa_replace_current_profile - replace the current tasks profiles * @profile: new profile  (NOT NULL) * * Returns: 0 or error on failure */int aa_replace_current_profile(struct aa_profile *profile){	struct aa_task_cxt *cxt = current_cred()->security;	struct cred *new;	BUG_ON(!profile); 	if (cxt->profile == profile)		return 0; 	new  = prepare_creds();	if (!new)		return -ENOMEM; 	cxt = new->security;	if (unconfined(profile) || (cxt->profile->ns != profile->ns)) {		/* if switching to unconfined or a different profile namespace		 * clear out context state		 */		aa_put_profile(cxt->previous);		aa_put_profile(cxt->onexec);		cxt->previous = NULL;		cxt->onexec = NULL;		cxt->token = 0;	}	/* be careful switching cxt->profile, when racing replacement it	 * is possible that cxt->profile->replacedby is the reference keeping	 * @profile valid, so make sure to get its reference before dropping	 * the reference on cxt->profile */	aa_get_profile(profile);	aa_put_profile(cxt->profile);	cxt->profile = profile; 	commit_creds(new);	return 0;} /** * aa_set_current_onexec - set the tasks change_profile to happen onexec * @profile: system profile to set at exec  (MAYBE NULL to clear value) * * Returns: 0 or error on failure */int aa_set_current_onexec(struct aa_profile *profile){	struct aa_task_cxt *cxt;	struct cred *new = prepare_creds();	if (!new)		return -ENOMEM; 	cxt = new->security;	aa_get_profile(profile);	aa_put_profile(cxt->onexec);	cxt->onexec = profile; 	commit_creds(new);	return 0;} /** * aa_set_current_hat - set the current tasks hat * @profile: profile 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_profile *profile, u64 token){	struct aa_task_cxt *cxt;	struct cred *new = prepare_creds();	if (!new)		return -ENOMEM;	BUG_ON(!profile); 	cxt = new->security;	if (!cxt->previous) {		/* transfer refcount */		cxt->previous = cxt->profile;		cxt->token = token;	} else if (cxt->token == token) {		aa_put_profile(cxt->profile);	} else {		/* previous_profile && cxt->token != token */		abort_creds(new);		return -EACCES;	}	cxt->profile = aa_get_profile(aa_newest_version(profile));	/* clear exec on switching context */	aa_put_profile(cxt->onexec);	cxt->onexec = NULL; 	commit_creds(new);	return 0;} /** * aa_restore_previous_profile - exit from hat context restoring the profile * @token: the token that must be matched to exit hat context * * Attempt to return out of a hat to the previous profile.  The token * must match the stored token value. * * Returns: 0 or error of failure */int aa_restore_previous_profile(u64 token){	struct aa_task_cxt *cxt;	struct cred *new = prepare_creds();	if (!new)		return -ENOMEM; 	cxt = new->security;	if (cxt->token != token) {		abort_creds(new);		return -EACCES;	}	/* ignore restores when there is no saved profile */	if (!cxt->previous) {		abort_creds(new);		return 0;	} 	aa_put_profile(cxt->profile);	cxt->profile = aa_newest_version(cxt->previous);	BUG_ON(!cxt->profile);	if (unlikely(cxt->profile != cxt->previous)) {		aa_get_profile(cxt->profile);		aa_put_profile(cxt->previous);	}	/* clear exec && prev information when restoring to previous context */	cxt->previous = NULL;	cxt->token = 0;	aa_put_profile(cxt->onexec);	cxt->onexec = NULL; 	commit_creds(new);	return 0;}