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gems-kernel/source/THIRDPARTY/xnu/bsd/kern/kern_authorization.c

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add darwin/xnu functionality
2024-06-03 11:29:39 -05:00
/*
* Copyright (c) 2004-2016 Apple Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. The rights granted to you under the License
* may not be used to create, or enable the creation or redistribution of,
* unlawful or unlicensed copies of an Apple operating system, or to
* circumvent, violate, or enable the circumvention or violation of, any
* terms of an Apple operating system software license agreement.
*
* Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*/
/*
* Centralized authorisation framework.
*/
#include <sys/appleapiopts.h>
#include <sys/param.h> /* XXX trim includes */
#include <sys/acct.h>
#include <sys/systm.h>
#include <sys/ucred.h>
#include <sys/proc_internal.h>
#include <sys/timeb.h>
#include <sys/times.h>
#include <sys/malloc.h>
#include <sys/vnode_internal.h>
#include <sys/kauth.h>
#include <sys/stat.h>
#include <security/audit/audit.h>
#include <sys/mount.h>
#include <sys/sysproto.h>
#include <mach/message.h>
#include <kern/locks.h>
/*
* Authorization scopes.
*/
LCK_GRP_DECLARE(kauth_lck_grp, "kauth");
static LCK_MTX_DECLARE(kauth_scope_mtx, &kauth_lck_grp);
#define KAUTH_SCOPELOCK() lck_mtx_lock(&kauth_scope_mtx);
#define KAUTH_SCOPEUNLOCK() lck_mtx_unlock(&kauth_scope_mtx);
/*
* We support listeners for scopes that have not been registered yet.
* If a listener comes in for a scope that is not active we hang the listener
* off our kauth_dangling_listeners list and once the scope becomes active we
* remove it from kauth_dangling_listeners and add it to the active scope.
*/
struct kauth_listener {
TAILQ_ENTRY(kauth_listener) kl_link;
const char * kl_identifier;
kauth_scope_callback_t kl_callback;
void * kl_idata;
};
/* XXX - kauth_todo - there is a race if a scope listener is removed while we
* we are in the kauth_authorize_action code path. We intentionally do not take
* a scope lock in order to get the best possible performance. we will fix this
* post Tiger.
* Until the race is fixed our kext clients are responsible for all active
* requests that may be in their callback code or on the way to their callback
* code before they free kauth_listener.kl_callback or kauth_listener.kl_idata.
* We keep copies of these in our kauth_local_listener in an attempt to limit
* our expose to unlisten race.
*/
struct kauth_local_listener {
kauth_listener_t kll_listenerp;
kauth_scope_callback_t kll_callback;
void * kll_idata;
};
typedef struct kauth_local_listener *kauth_local_listener_t;
static TAILQ_HEAD(, kauth_listener) kauth_dangling_listeners =
TAILQ_HEAD_INITIALIZER(kauth_dangling_listeners);
/*
* Scope listeners need to be reworked to be dynamic.
* We intentionally used a static table to avoid locking issues with linked
* lists. The listeners may be called quite often.
* XXX - kauth_todo
*/
#define KAUTH_SCOPE_MAX_LISTENERS 15
struct kauth_scope {
TAILQ_ENTRY(kauth_scope) ks_link;
volatile struct kauth_local_listener ks_listeners[KAUTH_SCOPE_MAX_LISTENERS];
const char * ks_identifier;
kauth_scope_callback_t ks_callback;
void * ks_idata;
u_int ks_flags;
};
/* values for kauth_scope.ks_flags */
#define KS_F_HAS_LISTENERS (1 << 0)
static TAILQ_HEAD(, kauth_scope) kauth_scopes = TAILQ_HEAD_INITIALIZER(kauth_scopes);
static int kauth_add_callback_to_scope(kauth_scope_t sp, kauth_listener_t klp);
static void kauth_scope_init(void);
static kauth_scope_t kauth_alloc_scope(const char *identifier, kauth_scope_callback_t callback, void *idata);
static kauth_listener_t kauth_alloc_listener(const char *identifier, kauth_scope_callback_t callback, void *idata);
#if 0
static int kauth_scope_valid(kauth_scope_t scope);
#endif
kauth_scope_t kauth_scope_process;
static int kauth_authorize_process_callback(kauth_cred_t _credential, void *_idata, kauth_action_t _action,
uintptr_t arg0, uintptr_t arg1, __unused uintptr_t arg2, __unused uintptr_t arg3);
kauth_scope_t kauth_scope_generic;
static int kauth_authorize_generic_callback(kauth_cred_t _credential, void *_idata, kauth_action_t _action,
uintptr_t arg0, uintptr_t arg1, uintptr_t arg2, uintptr_t arg3);
kauth_scope_t kauth_scope_fileop;
extern int cansignal(struct proc *, kauth_cred_t, struct proc *, int);
extern char * get_pathbuff(void);
extern void release_pathbuff(char *path);
/*
* Initialization.
*/
void
kauth_init(void)
{
/* bring up kauth subsystem components */
kauth_scope_init();
}
static void
kauth_scope_init(void)
{
kauth_scope_process = kauth_register_scope(KAUTH_SCOPE_PROCESS, kauth_authorize_process_callback, NULL);
kauth_scope_generic = kauth_register_scope(KAUTH_SCOPE_GENERIC, kauth_authorize_generic_callback, NULL);
kauth_scope_fileop = kauth_register_scope(KAUTH_SCOPE_FILEOP, NULL, NULL);
}
/*
* Scope registration.
*/
static kauth_scope_t
kauth_alloc_scope(const char *identifier, kauth_scope_callback_t callback, void *idata)
{
kauth_scope_t sp;
/*
* Allocate and populate the scope structure.
*/
sp = kalloc_type(struct kauth_scope, Z_WAITOK | Z_ZERO | Z_NOFAIL);
sp->ks_flags = 0;
sp->ks_identifier = identifier;
sp->ks_idata = idata;
sp->ks_callback = callback;
return sp;
}
static kauth_listener_t
kauth_alloc_listener(const char *identifier, kauth_scope_callback_t callback, void *idata)
{
kauth_listener_t lsp;
/*
* Allocate and populate the listener structure.
*/
lsp = kalloc_type(struct kauth_listener, Z_WAITOK | Z_NOFAIL);
lsp->kl_identifier = identifier;
lsp->kl_idata = idata;
lsp->kl_callback = callback;
return lsp;
}
kauth_scope_t
kauth_register_scope(const char *identifier, kauth_scope_callback_t callback, void *idata)
{
kauth_scope_t sp, tsp;
kauth_listener_t klp;
if ((sp = kauth_alloc_scope(identifier, callback, idata)) == NULL) {
return NULL;
}
/*
* Lock the list and insert.
*/
KAUTH_SCOPELOCK();
TAILQ_FOREACH(tsp, &kauth_scopes, ks_link) {
/* duplicate! */
if (strncmp(tsp->ks_identifier, identifier,
strlen(tsp->ks_identifier) + 1) == 0) {
KAUTH_SCOPEUNLOCK();
kfree_type(struct kauth_scope, sp);
return NULL;
}
}
TAILQ_INSERT_TAIL(&kauth_scopes, sp, ks_link);
/*
* Look for listeners waiting for this scope, move them to the active scope
* listener table.
* Note that we have to restart the scan every time we remove an entry
* from the list, since we can't remove the current item from the list.
*/
restart:
TAILQ_FOREACH(klp, &kauth_dangling_listeners, kl_link) {
if (strncmp(klp->kl_identifier, sp->ks_identifier,
strlen(klp->kl_identifier) + 1) == 0) {
/* found a match on the dangling listener list. add it to the
* the active scope.
*/
if (kauth_add_callback_to_scope(sp, klp) == 0) {
TAILQ_REMOVE(&kauth_dangling_listeners, klp, kl_link);
} else {
#if 0
printf("%s - failed to add listener to scope \"%s\" \n", __FUNCTION__, sp->ks_identifier);
#endif
break;
}
goto restart;
}
}
KAUTH_SCOPEUNLOCK();
return sp;
}
void
kauth_deregister_scope(kauth_scope_t scope)
{
int i;
KAUTH_SCOPELOCK();
TAILQ_REMOVE(&kauth_scopes, scope, ks_link);
/* relocate listeners back to the waiting list */
for (i = 0; i < KAUTH_SCOPE_MAX_LISTENERS; i++) {
if (scope->ks_listeners[i].kll_listenerp != NULL) {
TAILQ_INSERT_TAIL(&kauth_dangling_listeners, scope->ks_listeners[i].kll_listenerp, kl_link);
scope->ks_listeners[i].kll_listenerp = NULL;
/*
* XXX - kauth_todo - WARNING, do not clear kll_callback or
* kll_idata here. they are part of our scope unlisten race hack
*/
}
}
KAUTH_SCOPEUNLOCK();
kfree_type(struct kauth_scope, scope);
return;
}
kauth_listener_t
kauth_listen_scope(const char *identifier, kauth_scope_callback_t callback, void *idata)
{
kauth_listener_t klp;
kauth_scope_t sp;
if ((klp = kauth_alloc_listener(identifier, callback, idata)) == NULL) {
return NULL;
}
/*
* Lock the scope list and check to see whether this scope already exists.
*/
KAUTH_SCOPELOCK();
TAILQ_FOREACH(sp, &kauth_scopes, ks_link) {
if (strncmp(sp->ks_identifier, identifier,
strlen(sp->ks_identifier) + 1) == 0) {
/* scope exists, add it to scope listener table */
if (kauth_add_callback_to_scope(sp, klp) == 0) {
KAUTH_SCOPEUNLOCK();
return klp;
}
/* table already full */
KAUTH_SCOPEUNLOCK();
kfree_type(struct kauth_listener, klp);
return NULL;
}
}
/* scope doesn't exist, put on waiting list. */
TAILQ_INSERT_TAIL(&kauth_dangling_listeners, klp, kl_link);
KAUTH_SCOPEUNLOCK();
return klp;
}
void
kauth_unlisten_scope(kauth_listener_t listener)
{
kauth_scope_t sp;
kauth_listener_t klp;
int i, listener_count, do_free;
KAUTH_SCOPELOCK();
/* search the active scope for this listener */
TAILQ_FOREACH(sp, &kauth_scopes, ks_link) {
do_free = 0;
if ((sp->ks_flags & KS_F_HAS_LISTENERS) != 0) {
listener_count = 0;
for (i = 0; i < KAUTH_SCOPE_MAX_LISTENERS; i++) {
if (sp->ks_listeners[i].kll_listenerp == listener) {
sp->ks_listeners[i].kll_listenerp = NULL;
do_free = 1;
/*
* XXX - kauth_todo - WARNING, do not clear kll_callback or
* kll_idata here. they are part of our scope unlisten race hack
*/
} else if (sp->ks_listeners[i].kll_listenerp != NULL) {
listener_count++;
}
}
if (do_free) {
if (listener_count == 0) {
sp->ks_flags &= ~KS_F_HAS_LISTENERS;
}
KAUTH_SCOPEUNLOCK();
kfree_type(struct kauth_listener, listener);
return;
}
}
}
/* if not active, check the dangling list */
TAILQ_FOREACH(klp, &kauth_dangling_listeners, kl_link) {
if (klp == listener) {
TAILQ_REMOVE(&kauth_dangling_listeners, klp, kl_link);
KAUTH_SCOPEUNLOCK();
kfree_type(struct kauth_listener, listener);
return;
}
}
KAUTH_SCOPEUNLOCK();
return;
}
/*
* Authorization requests.
*
* Returns: 0 Success
* EPERM Operation not permitted
*
* Imputed: *arg3, modified Callback return - depends on callback
* modification of *arg3, if any
*/
int
kauth_authorize_action(kauth_scope_t scope, kauth_cred_t credential, kauth_action_t action,
uintptr_t arg0, uintptr_t arg1, uintptr_t arg2, uintptr_t arg3)
{
int result, ret, i;
/* ask the scope */
if (scope->ks_callback != NULL) {
result = scope->ks_callback(credential, scope->ks_idata, action, arg0, arg1, arg2, arg3);
} else {
result = KAUTH_RESULT_DEFER;
}
/* check with listeners */
if ((scope->ks_flags & KS_F_HAS_LISTENERS) != 0) {
for (i = 0; i < KAUTH_SCOPE_MAX_LISTENERS; i++) {
/* XXX - kauth_todo - there is a race here if listener is removed - we will fix this post Tiger.
* Until the race is fixed our kext clients are responsible for all active requests that may
* be in their callbacks or on the way to their callbacks before they free kl_callback or kl_idata.
* We keep copies of these in our kauth_local_listener in an attempt to limit our expose to
* unlisten race.
*/
if (scope->ks_listeners[i].kll_listenerp == NULL ||
scope->ks_listeners[i].kll_callback == NULL) {
continue;
}
ret = scope->ks_listeners[i].kll_callback(
credential, scope->ks_listeners[i].kll_idata,
action, arg0, arg1, arg2, arg3);
if ((ret == KAUTH_RESULT_DENY) ||
(result == KAUTH_RESULT_DEFER)) {
result = ret;
}
}
}
/* we need an explicit allow, or the auth fails */
/* XXX need a mechanism for auth failure to be signalled vs. denial */
return result == KAUTH_RESULT_ALLOW ? 0 : EPERM;
}
/*
* Default authorization handlers.
*/
int
kauth_authorize_allow(__unused kauth_cred_t credential, __unused void *idata, __unused kauth_action_t action,
__unused uintptr_t arg0, __unused uintptr_t arg1, __unused uintptr_t arg2, __unused uintptr_t arg3)
{
return KAUTH_RESULT_ALLOW;
}
#if 0
/*
* Debugging support.
*/
static int
kauth_scope_valid(kauth_scope_t scope)
{
kauth_scope_t sp;
KAUTH_SCOPELOCK();
TAILQ_FOREACH(sp, &kauth_scopes, ks_link) {
if (sp == scope) {
break;
}
}
KAUTH_SCOPEUNLOCK();
return (sp == NULL) ? 0 : 1;
}
#endif
/*
* Process authorization scope.
*/
int
kauth_authorize_process(kauth_cred_t credential, kauth_action_t action, struct proc *process, uintptr_t arg1, uintptr_t arg2, uintptr_t arg3)
{
return kauth_authorize_action(kauth_scope_process, credential, action, (uintptr_t)process, arg1, arg2, arg3);
}
static int
kauth_authorize_process_callback(kauth_cred_t credential, __unused void *idata, kauth_action_t action,
uintptr_t arg0, uintptr_t arg1, __unused uintptr_t arg2, __unused uintptr_t arg3)
{
switch (action) {
case KAUTH_PROCESS_CANSIGNAL:
panic("KAUTH_PROCESS_CANSIGNAL not implemented");
/* XXX credential wrong here */
/* arg0 - process to signal
* arg1 - signal to send the process
*/
if (cansignal(current_proc(), credential, (struct proc *)arg0, (int)arg1)) {
return KAUTH_RESULT_ALLOW;
}
break;
case KAUTH_PROCESS_CANTRACE:
/* current_proc() - process that will do the tracing
* arg0 - process to be traced
* arg1 - pointer to int - reason (errno) for denial
*/
if (cantrace(current_proc(), credential, (proc_t)arg0, (int *)arg1)) {
return KAUTH_RESULT_ALLOW;
}
break;
}
/* no explicit result, so defer to others in the chain */
return KAUTH_RESULT_DEFER;
}
/*
* File system operation authorization scope. This is really only a notification
* of the file system operation, not an authorization check. Thus the result is
* not relevant.
* arguments passed to KAUTH_FILEOP_OPEN listeners
* arg0 is pointer to vnode (vnode *) for given user path.
* arg1 is pointer to path (char *) passed in to open.
* arguments passed to KAUTH_FILEOP_CLOSE listeners
* arg0 is pointer to vnode (vnode *) for file to be closed.
* arg1 is pointer to path (char *) of file to be closed.
* arg2 is close flags.
* arguments passed to KAUTH_FILEOP_WILL_RENAME listeners
* arg0 is pointer to vnode (vnode *) of the file being renamed
* arg1 is pointer to the "from" path (char *)
* arg2 is pointer to the "to" path (char *)
* arguments passed to KAUTH_FILEOP_RENAME listeners
* arg0 is pointer to "from" path (char *).
* arg1 is pointer to "to" path (char *).
* arguments passed to KAUTH_FILEOP_EXCHANGE listeners
* arg0 is pointer to file 1 path (char *).
* arg1 is pointer to file 2 path (char *).
* arguments passed to KAUTH_FILEOP_EXEC listeners
* arg0 is pointer to vnode (vnode *) for executable.
* arg1 is pointer to path (char *) to executable.
*/
int
kauth_authorize_fileop_has_listeners(void)
{
/*
* return 1 if we have any listeners for the fileop scope
* otherwize return 0
*/
if ((kauth_scope_fileop->ks_flags & KS_F_HAS_LISTENERS) != 0) {
return 1;
}
return 0;
}
int
kauth_authorize_fileop(kauth_cred_t credential, kauth_action_t action, uintptr_t arg0, uintptr_t arg1)
{
char *namep = NULL;
int name_len;
uintptr_t arg2 = 0;
/* we do not have a primary handler for the fileop scope so bail out if
* there are no listeners.
*/
if ((kauth_scope_fileop->ks_flags & KS_F_HAS_LISTENERS) == 0) {
return 0;
}
if (action == KAUTH_FILEOP_OPEN ||
action == KAUTH_FILEOP_CLOSE ||
action == KAUTH_FILEOP_EXEC ||
action == KAUTH_FILEOP_WILL_RENAME) {
/* get path to the given vnode as a convenience to our listeners.
*/
namep = get_pathbuff();
name_len = MAXPATHLEN;
if (vn_getpath((vnode_t)arg0, namep, &name_len) != 0) {
release_pathbuff(namep);
return 0;
}
if (action == KAUTH_FILEOP_CLOSE ||
action == KAUTH_FILEOP_WILL_RENAME) {
/*
* - Close has some flags that come in via arg1.
* - Will-rename wants to pass the vnode and
* both paths to the listeners ("to" path
* starts in arg1, moves to arg2).
*/
arg2 = arg1;
}
arg1 = (uintptr_t)namep;
}
kauth_authorize_action(kauth_scope_fileop, credential, action, arg0, arg1, arg2, 0);
if (namep != NULL) {
release_pathbuff(namep);
}
return 0;
}
/*
* Generic authorization scope.
*/
int
kauth_authorize_generic(kauth_cred_t credential, kauth_action_t action)
{
if (credential == NULL) {
panic("auth against NULL credential");
}
return kauth_authorize_action(kauth_scope_generic, credential, action, 0, 0, 0, 0);
}
static int
kauth_authorize_generic_callback(kauth_cred_t credential, __unused void *idata, kauth_action_t action,
__unused uintptr_t arg0, __unused uintptr_t arg1, __unused uintptr_t arg2, __unused uintptr_t arg3)
{
switch (action) {
case KAUTH_GENERIC_ISSUSER:
/* XXX == 0 ? */
return (kauth_cred_getuid(credential) == 0) ?
KAUTH_RESULT_ALLOW : KAUTH_RESULT_DENY;
}
/* no explicit result, so defer to others in the chain */
return KAUTH_RESULT_DEFER;
}
/*
* ACL evaluator.
*
* Determines whether the credential has the requested rights for an object secured by the supplied
* ACL.
*
* Evaluation proceeds from the top down, with access denied if any ACE denies any of the requested
* rights, or granted if all of the requested rights are satisfied by the ACEs so far.
*/
int
kauth_acl_evaluate(kauth_cred_t cred, kauth_acl_eval_t eval)
{
int applies, error, i, gotguid;
kauth_ace_t ace;
guid_t guid;
uint32_t rights;
int wkguid;
if (cred == NULL) {
KAUTH_DEBUG(" ACL - got NULL credential");
return EINVAL;
}
if (eval == NULL) {
KAUTH_DEBUG(" ACL - got NULL ACL evaluator");
return EINVAL;
}
/* always allowed to do nothing */
if (eval->ae_requested == 0) {
eval->ae_result = KAUTH_RESULT_ALLOW;
return 0;
}
eval->ae_residual = eval->ae_requested;
eval->ae_found_deny = FALSE;
/*
* Get our guid for comparison purposes.
*/
if ((error = kauth_cred_getguid(cred, &guid)) != 0) {
KAUTH_DEBUG(" ACL - can't get credential GUID (%d)", error);
error = 0;
gotguid = 0;
} else {
gotguid = 1;
}
KAUTH_DEBUG(" ACL - %d entries, initial residual %x", eval->ae_count, eval->ae_residual);
for (i = 0, ace = eval->ae_acl; i < eval->ae_count; i++, ace++) {
/*
* Skip inherit-only entries.
*/
if (ace->ace_flags & KAUTH_ACE_ONLY_INHERIT) {
continue;
}
/*
* Expand generic rights, if appropriate.
*/
rights = ace->ace_rights;
if (rights & KAUTH_ACE_GENERIC_ALL) {
rights |= eval->ae_exp_gall;
}
if (rights & KAUTH_ACE_GENERIC_READ) {
rights |= eval->ae_exp_gread;
}
if (rights & KAUTH_ACE_GENERIC_WRITE) {
rights |= eval->ae_exp_gwrite;
}
if (rights & KAUTH_ACE_GENERIC_EXECUTE) {
rights |= eval->ae_exp_gexec;
}
/*
* Determine whether this entry applies to the current request. This
* saves us checking the GUID if the entry has nothing to do with what
* we're currently doing.
*/
switch (ace->ace_flags & KAUTH_ACE_KINDMASK) {
case KAUTH_ACE_PERMIT:
if (!(eval->ae_residual & rights)) {
continue;
}
break;
case KAUTH_ACE_DENY:
if (!(eval->ae_requested & rights)) {
continue;
}
eval->ae_found_deny = TRUE;
break;
default:
/* we don't recognise this ACE, skip it */
continue;
}
/*
* Verify whether this entry applies to the credential.
*/
wkguid = kauth_wellknown_guid(&ace->ace_applicable);
switch (wkguid) {
case KAUTH_WKG_OWNER:
applies = eval->ae_options & KAUTH_AEVAL_IS_OWNER;
break;
case KAUTH_WKG_GROUP:
if (!gotguid || (eval->ae_options & KAUTH_AEVAL_IN_GROUP_UNKNOWN)) {
applies = ((ace->ace_flags & KAUTH_ACE_KINDMASK) == KAUTH_ACE_DENY);
} else {
applies = eval->ae_options & KAUTH_AEVAL_IN_GROUP;
}
break;
/* we short-circuit these here rather than wasting time calling the group membership code */
case KAUTH_WKG_EVERYBODY:
applies = 1;
break;
case KAUTH_WKG_NOBODY:
applies = 0;
break;
default:
/* check to see whether it's exactly us, or a group we are a member of */
applies = !gotguid ? 0 : kauth_guid_equal(&guid, &ace->ace_applicable);
KAUTH_DEBUG(" ACL - ACE applicable " K_UUID_FMT " caller " K_UUID_FMT " %smatched",
K_UUID_ARG(ace->ace_applicable), K_UUID_ARG(guid), applies ? "" : "not ");
if (!applies) {
error = !gotguid ? ENOENT : kauth_cred_ismember_guid(cred, &ace->ace_applicable, &applies);
/*
* If we can't resolve group membership, we have to limit misbehaviour.
* If the ACE is an 'allow' ACE, assume the cred is not a member (avoid
* granting excess access). If the ACE is a 'deny' ACE, assume the cred
* is a member (avoid failing to deny).
*/
if (error != 0) {
KAUTH_DEBUG(" ACL[%d] - can't get membership, making pessimistic assumption", i);
switch (ace->ace_flags & KAUTH_ACE_KINDMASK) {
case KAUTH_ACE_PERMIT:
applies = 0;
break;
case KAUTH_ACE_DENY:
applies = 1;
break;
}
} else {
KAUTH_DEBUG(" ACL - %s group member", applies ? "is" : "not");
}
} else {
KAUTH_DEBUG(" ACL - entry matches caller");
}
}
if (!applies) {
continue;
}
/*
* Apply ACE to outstanding rights.
*/
switch (ace->ace_flags & KAUTH_ACE_KINDMASK) {
case KAUTH_ACE_PERMIT:
/* satisfy any rights that this ACE grants */
eval->ae_residual = eval->ae_residual & ~rights;
KAUTH_DEBUG(" ACL[%d] - rights %x leave residual %x", i, rights, eval->ae_residual);
/* all rights satisfied? */
if (eval->ae_residual == 0) {
eval->ae_result = KAUTH_RESULT_ALLOW;
return 0;
}
break;
case KAUTH_ACE_DENY:
/* deny the request if any of the requested rights is denied */
if (eval->ae_requested & rights) {
KAUTH_DEBUG(" ACL[%d] - denying based on %x", i, rights);
eval->ae_result = KAUTH_RESULT_DENY;
return 0;
}
break;
default:
KAUTH_DEBUG(" ACL - unknown entry kind %d", ace->ace_flags & KAUTH_ACE_KINDMASK);
break;
}
}
/* if not permitted, defer to other modes of authorisation */
eval->ae_result = KAUTH_RESULT_DEFER;
return 0;
}
/*
* Perform ACL inheritance and umask-ACL handling.
*
* Entries are inherited from the ACL on dvp. A caller-supplied
* ACL is in initial, and the result is output into product.
* If the process has a umask ACL and one is not supplied, we use
* the umask ACL.
* If isdir is set, the resultant ACL is for a directory, otherwise it is for a file.
*/
int
kauth_acl_inherit(vnode_t dvp, kauth_acl_t initial, kauth_acl_t *product, int isdir, vfs_context_t ctx)
{
int entries, error, index;
unsigned int i;
struct vnode_attr dva;
kauth_acl_t inherit, result;
/*
* Fetch the ACL from the directory. This should never fail.
* Note that we don't manage inheritance when the remote server is
* doing authorization, since this means server enforcement of
* inheritance semantics; we just want to compose the initial
* ACL and any inherited ACE entries from the container object.
*
* XXX TODO: <rdar://3634665> wants a "umask ACL" from the process.
*/
inherit = NULL;
/*
* If there is no initial ACL, or there is, and the initial ACLs
* flags do not request "no inheritance", then we inherit. This allows
* initial object creation via open_extended() and mkdir_extended()
* to reject inheritance for themselves and for inferior nodes by
* specifying a non-NULL inital ACL which has the KAUTH_ACL_NO_INHERIT
* flag set in the flags field.
*/
if ((initial == NULL || !(initial->acl_flags & KAUTH_ACL_NO_INHERIT)) &&
(dvp != NULL) && !vfs_authopaque(vnode_mount(dvp))) {
VATTR_INIT(&dva);
VATTR_WANTED(&dva, va_acl);
if ((error = vnode_getattr(dvp, &dva, ctx)) != 0) {
KAUTH_DEBUG(" ERROR - could not get parent directory ACL for inheritance");
return error;
}
if (VATTR_IS_SUPPORTED(&dva, va_acl)) {
inherit = dva.va_acl;
}
}
/*
* Compute the number of entries in the result ACL by scanning the
* input lists.
*/
entries = 0;
if (inherit != NULL) {
for (i = 0; i < inherit->acl_entrycount; i++) {
if (inherit->acl_ace[i].ace_flags & (isdir ? KAUTH_ACE_DIRECTORY_INHERIT : KAUTH_ACE_FILE_INHERIT)) {
entries++;
}
}
}
if (initial == NULL) {
/*
* XXX 3634665 TODO: if the initial ACL is not specfied by
* XXX the caller, fetch the umask ACL from the process,
* and use it in place of "initial".
*/
}
if (initial != NULL) {
if (initial->acl_entrycount != KAUTH_FILESEC_NOACL) {
entries += initial->acl_entrycount;
} else {
initial = NULL;
}
}
/*
* If there is no initial ACL, and no inheritable entries, the
* object should be created with no ACL at all.
* Note that this differs from the case where the initial ACL
* is empty, in which case the object must also have an empty ACL.
*/
if ((entries == 0) && (initial == NULL)) {
*product = NULL;
error = 0;
goto out;
}
/*
* Allocate the result buffer.
*/
if ((result = kauth_acl_alloc(entries)) == NULL) {
KAUTH_DEBUG(" ERROR - could not allocate %d-entry result buffer for inherited ACL", entries);
error = ENOMEM;
goto out;
}
/*
* Composition is simply:
* - initial direct ACEs
* - inherited ACEs from new parent
*/
index = 0;
if (initial != NULL) {
for (i = 0; i < initial->acl_entrycount; i++) {
if (!(initial->acl_ace[i].ace_flags & KAUTH_ACE_INHERITED)) {
result->acl_ace[index++] = initial->acl_ace[i];
}
}
KAUTH_DEBUG(" INHERIT - applied %d of %d initial entries", index, initial->acl_entrycount);
}
if (inherit != NULL) {
for (i = 0; i < inherit->acl_entrycount; i++) {
/*
* Inherit onto this object? We inherit only if
* the target object is a container object and the
* KAUTH_ACE_DIRECTORY_INHERIT bit is set, OR if
* if the target object is not a container, and
* the KAUTH_ACE_FILE_INHERIT bit is set.
*/
if (inherit->acl_ace[i].ace_flags & (isdir ? KAUTH_ACE_DIRECTORY_INHERIT : KAUTH_ACE_FILE_INHERIT)) {
result->acl_ace[index] = inherit->acl_ace[i];
result->acl_ace[index].ace_flags |= KAUTH_ACE_INHERITED;
result->acl_ace[index].ace_flags &= ~KAUTH_ACE_ONLY_INHERIT;
/*
* We do not re-inherit inheritance flags
* if the ACE from the container has a
* KAUTH_ACE_LIMIT_INHERIT, OR if the new
* object is not itself a container (since
* inheritance is always container-based).
*/
if ((result->acl_ace[index].ace_flags & KAUTH_ACE_LIMIT_INHERIT) || !isdir) {
result->acl_ace[index].ace_flags &=
~(KAUTH_ACE_INHERIT_CONTROL_FLAGS);
}
index++;
}
}
}
result->acl_entrycount = index;
*product = result;
KAUTH_DEBUG(" INHERIT - product ACL has %d entries", index);
error = 0;
out:
if (inherit != NULL) {
kauth_acl_free(inherit);
}
return error;
}
/*
* Optimistically copy in a kauth_filesec structure
*
* Parameters: xsecurity user space kauth_filesec_t
* xsecdstpp pointer to kauth_filesec_t to be
* modified to contain the contain a
* pointer to an allocated copy of the
* user space argument
*
* Returns: 0 Success
* ENOMEM Insufficient memory for the copy.
* EINVAL The user space data was invalid, or
* there were too many ACE entries.
* EFAULT The user space address was invalid;
* this may mean 'fsec_entrycount' in
* the user copy is corrupt/incorrect.
*
* Implicit returns: xsecdestpp, modified (only if successful!)
*
* Notes: The returned kauth_filesec_t is in host byte order
*
* The caller is responsible for freeing the returned
* kauth_filesec_t in the success case using the function
* kauth_filesec_free()
*
* Our largest initial guess is 32; this needs to move to
* a manifest constant in <sys/kauth.h>.
*/
int
kauth_copyinfilesec(user_addr_t xsecurity, kauth_filesec_t *xsecdestpp)
{
int error;
kauth_filesec_t fsec;
size_t count;
size_t copysize;
error = 0;
fsec = NULL;
/*
* Make a guess at the size of the filesec. We start with the base
* pointer, and look at how much room is left on the page, clipped
* to a sensible upper bound. If it turns out this isn't enough,
* we'll size based on the actual ACL contents and come back again.
*
* The upper bound must be less than KAUTH_ACL_MAX_ENTRIES. The
* value here is fairly arbitrary. It's ok to have a zero count.
*
* Because we're just using these values to make a guess about the
* number of entries, the actual address doesn't matter, only their
* relative offsets into the page. We take advantage of this to
* avoid an overflow in the rounding step (this is a user-provided
* parameter, so caution pays off).
*/
{
user_addr_t known_bound = (xsecurity & PAGE_MASK) + KAUTH_FILESEC_SIZE(0);
user_addr_t uaddr = (user_addr_t)mach_vm_round_page(known_bound);
count = (uaddr - known_bound) / sizeof(struct kauth_ace);
}
if (count > 32) {
count = 32;
}
restart:
if ((fsec = kauth_filesec_alloc((int)count)) == NULL) {
error = ENOMEM;
goto out;
}
copysize = KAUTH_FILESEC_SIZE(count);
if ((error = copyin(xsecurity, (caddr_t)fsec, copysize)) != 0) {
goto out;
}
/* validate the filesec header */
if (fsec->fsec_magic != KAUTH_FILESEC_MAGIC) {
error = EINVAL;
goto out;
}
/*
* Is there an ACL payload, and is it too big?
*/
if ((fsec->fsec_entrycount != KAUTH_FILESEC_NOACL) &&
(fsec->fsec_entrycount > count)) {
if (fsec->fsec_entrycount > KAUTH_ACL_MAX_ENTRIES) {
/* XXX This should be E2BIG */
error = EINVAL;
goto out;
}
count = fsec->fsec_entrycount;
kauth_filesec_free(fsec);
goto restart;
}
out:
if (error) {
if (fsec) {
kauth_filesec_free(fsec);
}
} else {
*xsecdestpp = fsec;
AUDIT_ARG(opaque, fsec, copysize);
}
return error;
}
/*
* Allocate a block of memory containing a filesec structure, immediately
* followed by 'count' kauth_ace structures.
*
* Parameters: count Number of kauth_ace structures needed
*
* Returns: !NULL A pointer to the allocated block
* NULL Invalid 'count' or insufficient memory
*
* Notes: Returned memory area assumes that the structures are packed
* densely, so this function may only be used by code that also
* assumes no padding following structures.
*
* The returned structure must be freed by the caller using the
* function kauth_filesec_free(), in case we decide to use an
* allocation mechanism that is aware of the object size at some
* point, since the object size is only available by introspecting
* the object itself.
*/
kauth_filesec_t
kauth_filesec_alloc(int count)
{
kauth_filesec_t fsp;
/* if the caller hasn't given us a valid size hint, assume the worst */
if ((count < 0) || (count > KAUTH_ACL_MAX_ENTRIES)) {
return NULL;
}
fsp = kalloc_data(KAUTH_FILESEC_SIZE(count), Z_WAITOK);
if (fsp != NULL) {
fsp->fsec_magic = KAUTH_FILESEC_MAGIC;
fsp->fsec_owner = kauth_null_guid;
fsp->fsec_group = kauth_null_guid;
fsp->fsec_entrycount = KAUTH_FILESEC_NOACL;
fsp->fsec_flags = 0;
}
return fsp;
}
/*
* Free a kauth_filesec_t that was previous allocated, either by a direct
* call to kauth_filesec_alloc() or by calling a function that calls it.
*
* Parameters: fsp kauth_filesec_t to free
*
* Returns: (void)
*
* Notes: The kauth_filesec_t to be freed is assumed to be in host
* byte order so that this function can introspect it in the
* future to determine its size, if necesssary.
*/
void
kauth_filesec_free(kauth_filesec_t fsp)
{
#ifdef KAUTH_DEBUG_ENABLE
if (fsp == KAUTH_FILESEC_NONE) {
panic("freeing KAUTH_FILESEC_NONE");
}
if (fsp == KAUTH_FILESEC_WANTED) {
panic("freeing KAUTH_FILESEC_WANTED");
}
#endif
kfree_data_addr(fsp);
}
/*
* Set the endianness of a filesec and an ACL; if 'acl' is NULL, use the
* ACL interior to 'fsec' instead. If the endianness doesn't change, then
* this function will have no effect.
*
* Parameters: kendian The endianness to set; this is either
* KAUTH_ENDIAN_HOST or KAUTH_ENDIAN_DISK.
* fsec The filesec to convert.
* acl The ACL to convert (optional)
*
* Returns: (void)
*
* Notes: We use ntohl() because it has a transitive property on Intel
* machines and no effect on PPC mancines. This guarantees us
* that the swapping only occurs if the endiannes is wrong.
*/
void
kauth_filesec_acl_setendian(int kendian, kauth_filesec_t fsec, kauth_acl_t acl)
{
uint32_t compare_magic = KAUTH_FILESEC_MAGIC;
uint32_t invert_magic = ntohl(KAUTH_FILESEC_MAGIC);
uint32_t compare_acl_entrycount;
uint32_t i;
if (compare_magic == invert_magic) {
return;
}
/* If no ACL, use ACL interior to 'fsec' instead */
if (acl == NULL) {
acl = &fsec->fsec_acl;
}
compare_acl_entrycount = acl->acl_entrycount;
/*
* Only convert what needs to be converted, and only if the arguments
* are valid. The following switch and tests effectively reject
* conversions on invalid magic numbers as a desirable side effect.
*/
switch (kendian) {
case KAUTH_ENDIAN_HOST: /* not in host, convert to host */
if (fsec->fsec_magic != invert_magic) {
return;
}
/* acl_entrycount is byteswapped */
compare_acl_entrycount = ntohl(acl->acl_entrycount);
break;
case KAUTH_ENDIAN_DISK: /* not in disk, convert to disk */
if (fsec->fsec_magic != compare_magic) {
return;
}
break;
default: /* bad argument */
return;
}
/* We are go for conversion */
fsec->fsec_magic = ntohl(fsec->fsec_magic);
acl->acl_entrycount = ntohl(acl->acl_entrycount);
if (compare_acl_entrycount != KAUTH_FILESEC_NOACL) {
acl->acl_flags = ntohl(acl->acl_flags);
/* swap ACE rights and flags */
for (i = 0; i < compare_acl_entrycount; i++) {
acl->acl_ace[i].ace_flags = ntohl(acl->acl_ace[i].ace_flags);
acl->acl_ace[i].ace_rights = ntohl(acl->acl_ace[i].ace_rights);
}
}
}
/*
* Allocate an ACL buffer.
*/
kauth_acl_t
kauth_acl_alloc(int count)
{
/* if the caller hasn't given us a valid size hint, assume the worst */
if ((count < 0) || (count > KAUTH_ACL_MAX_ENTRIES)) {
return NULL;
}
return kalloc_data(KAUTH_ACL_SIZE(count), Z_WAITOK | Z_ZERO);
}
void
kauth_acl_free(kauth_acl_t aclp)
{
kfree_data_addr(aclp);
}
/*
* WARNING - caller must hold KAUTH_SCOPELOCK
*/
static int
kauth_add_callback_to_scope(kauth_scope_t sp, kauth_listener_t klp)
{
int i;
for (i = 0; i < KAUTH_SCOPE_MAX_LISTENERS; i++) {
if (sp->ks_listeners[i].kll_listenerp == NULL) {
sp->ks_listeners[i].kll_callback = klp->kl_callback;
sp->ks_listeners[i].kll_idata = klp->kl_idata;
sp->ks_listeners[i].kll_listenerp = klp;
sp->ks_flags |= KS_F_HAS_LISTENERS;
return 0;
}
}
return ENOSPC;
}
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