cmds/servicemanager/service_manager.c - platform/frameworks/native - Gitiles

 /* Copyright 2008 The Android Open Source Project
  */

 #include <errno.h>
 #include <fcntl.h>
 #include <inttypes.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>

 #include <cutils/multiuser.h>

 #include <private/android_filesystem_config.h>

 #include <selinux/android.h>
 #include <selinux/avc.h>

 #include "binder.h"

 #ifdef VENDORSERVICEMANAGER
 #define LOG_TAG "VendorServiceManager"
 #else
 #define LOG_TAG "ServiceManager"
 #endif
 #include <log/log.h>

 struct audit_data {
     pid_t pid;
     uid_t uid;
     const char *name;
 };

 const char *str8(const uint16_t *x, size_t x_len)
 {
     static char buf[128];
     size_t max = 127;
     char *p = buf;

     if (x_len < max) {
         max = x_len;
     }

     if (x) {
         while ((max > 0) && (*x != '\0')) {
             *p++ = *x++;
             max--;
         }
     }
     *p++ = 0;
     return buf;
 }

 int str16eq(const uint16_t *a, const char *b)
 {
     while (*a && *b)
         if (*a++ != *b++) return 0;
     if (*a || *b)
         return 0;
     return 1;
 }

 static char *service_manager_context;
 static struct selabel_handle* sehandle;

 static bool check_mac_perms(pid_t spid, uid_t uid, const char *tctx, const char *perm, const char *name)
 {
     char *sctx = NULL;
     const char *class = "service_manager";
     bool allowed;
     struct audit_data ad;

     if (getpidcon(spid, &sctx) < 0) {
         ALOGE("SELinux: getpidcon(pid=%d) failed to retrieve pid context.\n", spid);
         return false;
     }

     ad.pid = spid;
     ad.uid = uid;
     ad.name = name;

     int result = selinux_check_access(sctx, tctx, class, perm, (void *) &ad);
     allowed = (result == 0);

     freecon(sctx);
     return allowed;
 }

 static bool check_mac_perms_from_getcon(pid_t spid, uid_t uid, const char *perm)
 {
     return check_mac_perms(spid, uid, service_manager_context, perm, NULL);
 }

 static bool check_mac_perms_from_lookup(pid_t spid, uid_t uid, const char *perm, const char *name)
 {
     bool allowed;
     char *tctx = NULL;

     if (!sehandle) {
         ALOGE("SELinux: Failed to find sehandle. Aborting service_manager.\n");
         abort();
     }

     if (selabel_lookup(sehandle, &tctx, name, 0) != 0) {
         ALOGE("SELinux: No match for %s in service_contexts.\n", name);
         return false;
     }

     allowed = check_mac_perms(spid, uid, tctx, perm, name);
     freecon(tctx);
     return allowed;
 }

 static int svc_can_register(const uint16_t *name, size_t name_len, pid_t spid, uid_t uid)
 {
     const char *perm = "add";

     if (multiuser_get_app_id(uid) >= AID_APP) {
         return 0; /* Don't allow apps to register services */
     }

     return check_mac_perms_from_lookup(spid, uid, perm, str8(name, name_len)) ? 1 : 0;
 }

 static int svc_can_list(pid_t spid, uid_t uid)
 {
     const char *perm = "list";
     return check_mac_perms_from_getcon(spid, uid, perm) ? 1 : 0;
 }

 static int svc_can_find(const uint16_t *name, size_t name_len, pid_t spid, uid_t uid)
 {
     const char *perm = "find";
     return check_mac_perms_from_lookup(spid, uid, perm, str8(name, name_len)) ? 1 : 0;
 }

 struct svcinfo
 {
     struct svcinfo *next;
     uint32_t handle;
     struct binder_death death;
     int allow_isolated;
     size_t len;
     uint16_t name[0];
 };

 struct svcinfo *svclist = NULL;

 struct svcinfo *find_svc(const uint16_t *s16, size_t len)
 {
     struct svcinfo *si;

     for (si = svclist; si; si = si->next) {
         if ((len == si->len) &&
             !memcmp(s16, si->name, len * sizeof(uint16_t))) {
             return si;
         }
     }
     return NULL;
 }

 void svcinfo_death(struct binder_state *bs, void *ptr)
 {
     struct svcinfo *si = (struct svcinfo* ) ptr;

     ALOGI("service '%s' died\n", str8(si->name, si->len));
     if (si->handle) {
         binder_release(bs, si->handle);
         si->handle = 0;
     }
 }

 uint16_t svcmgr_id[] = {
     'a','n','d','r','o','i','d','.','o','s','.',
     'I','S','e','r','v','i','c','e','M','a','n','a','g','e','r'
 };


 uint32_t do_find_service(const uint16_t *s, size_t len, uid_t uid, pid_t spid)
 {
     struct svcinfo *si = find_svc(s, len);

     if (!si || !si->handle) {
         return 0;
     }

     if (!si->allow_isolated) {
         // If this service doesn't allow access from isolated processes,
         // then check the uid to see if it is isolated.
         uid_t appid = uid % AID_USER;
         if (appid >= AID_ISOLATED_START && appid <= AID_ISOLATED_END) {
             return 0;
         }
     }

     if (!svc_can_find(s, len, spid, uid)) {
         return 0;
     }

     return si->handle;
 }

 int do_add_service(struct binder_state *bs,
                    const uint16_t *s, size_t len,
                    uint32_t handle, uid_t uid, int allow_isolated,
                    pid_t spid)
 {
     struct svcinfo *si;

     //ALOGI("add_service('%s',%x,%s) uid=%d\n", str8(s, len), handle,
     //        allow_isolated ? "allow_isolated" : "!allow_isolated", uid);

     if (!handle || (len == 0) || (len > 127))
         return -1;

     if (!svc_can_register(s, len, spid, uid)) {
         ALOGE("add_service('%s',%x) uid=%d - PERMISSION DENIED\n",
              str8(s, len), handle, uid);
         return -1;
     }

     si = find_svc(s, len);
     if (si) {
         if (si->handle) {
             ALOGE("add_service('%s',%x) uid=%d - ALREADY REGISTERED, OVERRIDE\n",
                  str8(s, len), handle, uid);
             svcinfo_death(bs, si);
         }
         si->handle = handle;
     } else {
         si = malloc(sizeof(*si) + (len + 1) * sizeof(uint16_t));
         if (!si) {
             ALOGE("add_service('%s',%x) uid=%d - OUT OF MEMORY\n",
                  str8(s, len), handle, uid);
             return -1;
         }
         si->handle = handle;
         si->len = len;
         memcpy(si->name, s, (len + 1) * sizeof(uint16_t));
         si->name[len] = '\0';
         si->death.func = (void*) svcinfo_death;
         si->death.ptr = si;
         si->allow_isolated = allow_isolated;
         si->next = svclist;
         svclist = si;
     }

     binder_acquire(bs, handle);
     binder_link_to_death(bs, handle, &si->death);
     return 0;
 }

 int svcmgr_handler(struct binder_state *bs,
                    struct binder_transaction_data *txn,
                    struct binder_io *msg,
                    struct binder_io *reply)
 {
     struct svcinfo *si;
     uint16_t *s;
     size_t len;
     uint32_t handle;
     uint32_t strict_policy;
     int allow_isolated;

     //ALOGI("target=%p code=%d pid=%d uid=%d\n",
     //      (void*) txn->target.ptr, txn->code, txn->sender_pid, txn->sender_euid);

     if (txn->target.ptr != BINDER_SERVICE_MANAGER)
         return -1;

     if (txn->code == PING_TRANSACTION)
         return 0;

     // Equivalent to Parcel::enforceInterface(), reading the RPC
     // header with the strict mode policy mask and the interface name.
     // Note that we ignore the strict_policy and don't propagate it
     // further (since we do no outbound RPCs anyway).
     strict_policy = bio_get_uint32(msg);
     s = bio_get_string16(msg, &len);
     if (s == NULL) {
         return -1;
     }

     if ((len != (sizeof(svcmgr_id) / 2)) ||
         memcmp(svcmgr_id, s, sizeof(svcmgr_id))) {
         fprintf(stderr,"invalid id %s\n", str8(s, len));
         return -1;
     }

     if (sehandle && selinux_status_updated() > 0) {
 #ifdef VENDORSERVICEMANAGER
         struct selabel_handle *tmp_sehandle = selinux_android_vendor_service_context_handle();
 #else
         struct selabel_handle *tmp_sehandle = selinux_android_service_context_handle();
 #endif
         if (tmp_sehandle) {
             selabel_close(sehandle);
             sehandle = tmp_sehandle;
         }
     }

     switch(txn->code) {
     case SVC_MGR_GET_SERVICE:
     case SVC_MGR_CHECK_SERVICE:
         s = bio_get_string16(msg, &len);
         if (s == NULL) {
             return -1;
         }
         handle = do_find_service(s, len, txn->sender_euid, txn->sender_pid);
         if (!handle)
             break;
         bio_put_ref(reply, handle);
         return 0;

     case SVC_MGR_ADD_SERVICE:
         s = bio_get_string16(msg, &len);
         if (s == NULL) {
             return -1;
         }
         handle = bio_get_ref(msg);
         allow_isolated = bio_get_uint32(msg) ? 1 : 0;
         if (do_add_service(bs, s, len, handle, txn->sender_euid,
             allow_isolated, txn->sender_pid))
             return -1;
         break;

     case SVC_MGR_LIST_SERVICES: {
         uint32_t n = bio_get_uint32(msg);

         if (!svc_can_list(txn->sender_pid, txn->sender_euid)) {
             ALOGE("list_service() uid=%d - PERMISSION DENIED\n",
                     txn->sender_euid);
             return -1;
         }
         si = svclist;
         while ((n-- > 0) && si)
             si = si->next;
         if (si) {
             bio_put_string16(reply, si->name);
             return 0;
         }
         return -1;
     }
     default:
         ALOGE("unknown code %d\n", txn->code);
         return -1;
     }

     bio_put_uint32(reply, 0);
     return 0;
 }


 static int audit_callback(void *data, __unused security_class_t cls, char *buf, size_t len)
 {
     struct audit_data *ad = (struct audit_data *)data;

     if (!ad || !ad->name) {
         ALOGE("No service manager audit data");
         return 0;
     }

     snprintf(buf, len, "service=%s pid=%d uid=%d", ad->name, ad->pid, ad->uid);
     return 0;
 }

 int main(int argc, char** argv)
 {
     struct binder_state *bs;
     union selinux_callback cb;
     char *driver;

     if (argc > 1) {
         driver = argv[1];
     } else {
         driver = "/dev/binder";
     }

     bs = binder_open(driver, 128*1024);
     if (!bs) {
 #ifdef VENDORSERVICEMANAGER
         ALOGW("failed to open binder driver %s\n", driver);
         while (true) {
             sleep(UINT_MAX);
         }
 #else
         ALOGE("failed to open binder driver %s\n", driver);
 #endif
         return -1;
     }

     if (binder_become_context_manager(bs)) {
         ALOGE("cannot become context manager (%s)\n", strerror(errno));
         return -1;
     }

     cb.func_audit = audit_callback;
     selinux_set_callback(SELINUX_CB_AUDIT, cb);
     cb.func_log = selinux_log_callback;
     selinux_set_callback(SELINUX_CB_LOG, cb);

 #ifdef VENDORSERVICEMANAGER
     sehandle = selinux_android_vendor_service_context_handle();
 #else
     sehandle = selinux_android_service_context_handle();
 #endif
     selinux_status_open(true);

     if (sehandle == NULL) {
         ALOGE("SELinux: Failed to acquire sehandle. Aborting.\n");
         abort();
     }

     if (getcon(&service_manager_context) != 0) {
         ALOGE("SELinux: Failed to acquire service_manager context. Aborting.\n");
         abort();
     }


     binder_loop(bs, svcmgr_handler);

     return 0;
 }
	/* Copyright 2008 The Android Open Source Project
	*/

	#include <errno.h>
	#include <fcntl.h>
	#include <inttypes.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>

	#include <cutils/multiuser.h>

	#include <private/android_filesystem_config.h>

	#include <selinux/android.h>
	#include <selinux/avc.h>

	#include "binder.h"

	#ifdef VENDORSERVICEMANAGER
	#define LOG_TAG "VendorServiceManager"
	#else
	#define LOG_TAG "ServiceManager"
	#endif
	#include <log/log.h>

	struct audit_data {
	pid_t pid;
	uid_t uid;
	const char *name;
	};

	const char str8(const uint16_t x, size_t x_len)
	{
	static char buf[128];
	size_t max = 127;
	char *p = buf;

	if (x_len < max) {
	max = x_len;
	}

	if (x) {
	while ((max > 0) && (*x != '\0')) {
	p++ = x++;
	max--;
	}
	}
	*p++ = 0;
	return buf;
	}

	int str16eq(const uint16_t a, const char b)
	{
	while (a && b)
	if (a++ != b++) return 0;
	if (a \|\| b)
	return 0;
	return 1;
	}

	static char *service_manager_context;
	static struct selabel_handle* sehandle;

	static bool check_mac_perms(pid_t spid, uid_t uid, const char tctx, const char perm, const char *name)
	{
	char *sctx = NULL;
	const char *class = "service_manager";
	bool allowed;
	struct audit_data ad;

	if (getpidcon(spid, &sctx) < 0) {
	ALOGE("SELinux: getpidcon(pid=%d) failed to retrieve pid context.\n", spid);
	return false;
	}

	ad.pid = spid;
	ad.uid = uid;
	ad.name = name;

	int result = selinux_check_access(sctx, tctx, class, perm, (void *) &ad);
	allowed = (result == 0);

	freecon(sctx);
	return allowed;
	}

	static bool check_mac_perms_from_getcon(pid_t spid, uid_t uid, const char *perm)
	{
	return check_mac_perms(spid, uid, service_manager_context, perm, NULL);
	}

	static bool check_mac_perms_from_lookup(pid_t spid, uid_t uid, const char perm, const char name)
	{
	bool allowed;
	char *tctx = NULL;

	if (!sehandle) {
	ALOGE("SELinux: Failed to find sehandle. Aborting service_manager.\n");
	abort();
	}

	if (selabel_lookup(sehandle, &tctx, name, 0) != 0) {
	ALOGE("SELinux: No match for %s in service_contexts.\n", name);
	return false;
	}

	allowed = check_mac_perms(spid, uid, tctx, perm, name);
	freecon(tctx);
	return allowed;
	}

	static int svc_can_register(const uint16_t *name, size_t name_len, pid_t spid, uid_t uid)
	{
	const char *perm = "add";

	if (multiuser_get_app_id(uid) >= AID_APP) {
	return 0; /* Don't allow apps to register services */
	}

	return check_mac_perms_from_lookup(spid, uid, perm, str8(name, name_len)) ? 1 : 0;
	}

	static int svc_can_list(pid_t spid, uid_t uid)
	{
	const char *perm = "list";
	return check_mac_perms_from_getcon(spid, uid, perm) ? 1 : 0;
	}

	static int svc_can_find(const uint16_t *name, size_t name_len, pid_t spid, uid_t uid)
	{
	const char *perm = "find";
	return check_mac_perms_from_lookup(spid, uid, perm, str8(name, name_len)) ? 1 : 0;
	}

	struct svcinfo
	{
	struct svcinfo *next;
	uint32_t handle;
	struct binder_death death;
	int allow_isolated;
	size_t len;
	uint16_t name[0];
	};

	struct svcinfo *svclist = NULL;

	struct svcinfo find_svc(const uint16_t s16, size_t len)
	{
	struct svcinfo *si;

	for (si = svclist; si; si = si->next) {
	if ((len == si->len) &&
	!memcmp(s16, si->name, len * sizeof(uint16_t))) {
	return si;
	}
	}
	return NULL;
	}

	void svcinfo_death(struct binder_state bs, void ptr)
	{
	struct svcinfo si = (struct svcinfo ) ptr;

	ALOGI("service '%s' died\n", str8(si->name, si->len));
	if (si->handle) {
	binder_release(bs, si->handle);
	si->handle = 0;
	}
	}

	uint16_t svcmgr_id[] = {
	'a','n','d','r','o','i','d','.','o','s','.',
	'I','S','e','r','v','i','c','e','M','a','n','a','g','e','r'
	};


	uint32_t do_find_service(const uint16_t *s, size_t len, uid_t uid, pid_t spid)
	{
	struct svcinfo *si = find_svc(s, len);

	if (!si \|\| !si->handle) {
	return 0;
	}

	if (!si->allow_isolated) {
	// If this service doesn't allow access from isolated processes,
	// then check the uid to see if it is isolated.
	uid_t appid = uid % AID_USER;
	if (appid >= AID_ISOLATED_START && appid <= AID_ISOLATED_END) {
	return 0;
	}
	}

	if (!svc_can_find(s, len, spid, uid)) {
	return 0;
	}

	return si->handle;
	}

	int do_add_service(struct binder_state *bs,
	const uint16_t *s, size_t len,
	uint32_t handle, uid_t uid, int allow_isolated,
	pid_t spid)
	{
	struct svcinfo *si;

	//ALOGI("add_service('%s',%x,%s) uid=%d\n", str8(s, len), handle,
	// allow_isolated ? "allow_isolated" : "!allow_isolated", uid);

	if (!handle \|\| (len == 0) \|\| (len > 127))
	return -1;

	if (!svc_can_register(s, len, spid, uid)) {
	ALOGE("add_service('%s',%x) uid=%d - PERMISSION DENIED\n",
	str8(s, len), handle, uid);
	return -1;
	}

	si = find_svc(s, len);
	if (si) {
	if (si->handle) {
	ALOGE("add_service('%s',%x) uid=%d - ALREADY REGISTERED, OVERRIDE\n",
	str8(s, len), handle, uid);
	svcinfo_death(bs, si);
	}
	si->handle = handle;
	} else {
	si = malloc(sizeof(si) + (len + 1) sizeof(uint16_t));
	if (!si) {
	ALOGE("add_service('%s',%x) uid=%d - OUT OF MEMORY\n",
	str8(s, len), handle, uid);
	return -1;
	}
	si->handle = handle;
	si->len = len;
	memcpy(si->name, s, (len + 1) * sizeof(uint16_t));
	si->name[len] = '\0';
	si->death.func = (void*) svcinfo_death;
	si->death.ptr = si;
	si->allow_isolated = allow_isolated;
	si->next = svclist;
	svclist = si;
	}

	binder_acquire(bs, handle);
	binder_link_to_death(bs, handle, &si->death);
	return 0;
	}

	int svcmgr_handler(struct binder_state *bs,
	struct binder_transaction_data *txn,
	struct binder_io *msg,
	struct binder_io *reply)
	{
	struct svcinfo *si;
	uint16_t *s;
	size_t len;
	uint32_t handle;
	uint32_t strict_policy;
	int allow_isolated;

	//ALOGI("target=%p code=%d pid=%d uid=%d\n",
	// (void*) txn->target.ptr, txn->code, txn->sender_pid, txn->sender_euid);

	if (txn->target.ptr != BINDER_SERVICE_MANAGER)
	return -1;

	if (txn->code == PING_TRANSACTION)
	return 0;

	// Equivalent to Parcel::enforceInterface(), reading the RPC
	// header with the strict mode policy mask and the interface name.
	// Note that we ignore the strict_policy and don't propagate it
	// further (since we do no outbound RPCs anyway).
	strict_policy = bio_get_uint32(msg);
	s = bio_get_string16(msg, &len);
	if (s == NULL) {
	return -1;
	}

	if ((len != (sizeof(svcmgr_id) / 2)) \|\|
	memcmp(svcmgr_id, s, sizeof(svcmgr_id))) {
	fprintf(stderr,"invalid id %s\n", str8(s, len));
	return -1;
	}

	if (sehandle && selinux_status_updated() > 0) {
	#ifdef VENDORSERVICEMANAGER
	struct selabel_handle *tmp_sehandle = selinux_android_vendor_service_context_handle();
	#else
	struct selabel_handle *tmp_sehandle = selinux_android_service_context_handle();
	#endif
	if (tmp_sehandle) {
	selabel_close(sehandle);
	sehandle = tmp_sehandle;
	}
	}

	switch(txn->code) {
	case SVC_MGR_GET_SERVICE:
	case SVC_MGR_CHECK_SERVICE:
	s = bio_get_string16(msg, &len);
	if (s == NULL) {
	return -1;
	}
	handle = do_find_service(s, len, txn->sender_euid, txn->sender_pid);
	if (!handle)
	break;
	bio_put_ref(reply, handle);
	return 0;

	case SVC_MGR_ADD_SERVICE:
	s = bio_get_string16(msg, &len);
	if (s == NULL) {
	return -1;
	}
	handle = bio_get_ref(msg);
	allow_isolated = bio_get_uint32(msg) ? 1 : 0;
	if (do_add_service(bs, s, len, handle, txn->sender_euid,
	allow_isolated, txn->sender_pid))
	return -1;
	break;

	case SVC_MGR_LIST_SERVICES: {
	uint32_t n = bio_get_uint32(msg);

	if (!svc_can_list(txn->sender_pid, txn->sender_euid)) {
	ALOGE("list_service() uid=%d - PERMISSION DENIED\n",
	txn->sender_euid);
	return -1;
	}
	si = svclist;
	while ((n-- > 0) && si)
	si = si->next;
	if (si) {
	bio_put_string16(reply, si->name);
	return 0;
	}
	return -1;
	}
	default:
	ALOGE("unknown code %d\n", txn->code);
	return -1;
	}

	bio_put_uint32(reply, 0);
	return 0;
	}


	static int audit_callback(void data, __unused security_class_t cls, char buf, size_t len)
	{
	struct audit_data ad = (struct audit_data )data;

	if (!ad \|\| !ad->name) {
	ALOGE("No service manager audit data");
	return 0;
	}

	snprintf(buf, len, "service=%s pid=%d uid=%d", ad->name, ad->pid, ad->uid);
	return 0;
	}

	int main(int argc, char** argv)
	{
	struct binder_state *bs;
	union selinux_callback cb;
	char *driver;

	if (argc > 1) {
	driver = argv[1];
	} else {
	driver = "/dev/binder";
	}

	bs = binder_open(driver, 128*1024);
	if (!bs) {
	#ifdef VENDORSERVICEMANAGER
	ALOGW("failed to open binder driver %s\n", driver);
	while (true) {
	sleep(UINT_MAX);
	}
	#else
	ALOGE("failed to open binder driver %s\n", driver);
	#endif
	return -1;
	}

	if (binder_become_context_manager(bs)) {
	ALOGE("cannot become context manager (%s)\n", strerror(errno));
	return -1;
	}

	cb.func_audit = audit_callback;
	selinux_set_callback(SELINUX_CB_AUDIT, cb);
	cb.func_log = selinux_log_callback;
	selinux_set_callback(SELINUX_CB_LOG, cb);

	#ifdef VENDORSERVICEMANAGER
	sehandle = selinux_android_vendor_service_context_handle();
	#else
	sehandle = selinux_android_service_context_handle();
	#endif
	selinux_status_open(true);

	if (sehandle == NULL) {
	ALOGE("SELinux: Failed to acquire sehandle. Aborting.\n");
	abort();
	}

	if (getcon(&service_manager_context) != 0) {
	ALOGE("SELinux: Failed to acquire service_manager context. Aborting.\n");
	abort();
	}


	binder_loop(bs, svcmgr_handler);

	return 0;
	}