| /* 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 <private/android_filesystem_config.h> |
| |
| #include <selinux/android.h> |
| #include <selinux/avc.h> |
| |
| #include "binder.h" |
| |
| #if 0 |
| #define ALOGI(x...) fprintf(stderr, "svcmgr: " x) |
| #define ALOGE(x...) fprintf(stderr, "svcmgr: " x) |
| #else |
| #define LOG_TAG "ServiceManager" |
| #include <cutils/log.h> |
| #endif |
| |
| 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 int selinux_enabled; |
| static char *service_manager_context; |
| static struct selabel_handle* sehandle; |
| |
| static bool check_mac_perms(pid_t spid, const char *tctx, const char *perm, const char *name) |
| { |
| char *sctx = NULL; |
| const char *class = "service_manager"; |
| bool allowed; |
| |
| if (getpidcon(spid, &sctx) < 0) { |
| ALOGE("SELinux: getpidcon(pid=%d) failed to retrieve pid context.\n", spid); |
| return false; |
| } |
| |
| int result = selinux_check_access(sctx, tctx, class, perm, (void *) name); |
| allowed = (result == 0); |
| |
| freecon(sctx); |
| return allowed; |
| } |
| |
| static bool check_mac_perms_from_getcon(pid_t spid, const char *perm) |
| { |
| if (selinux_enabled <= 0) { |
| return true; |
| } |
| |
| return check_mac_perms(spid, service_manager_context, perm, NULL); |
| } |
| |
| static bool check_mac_perms_from_lookup(pid_t spid, const char *perm, const char *name) |
| { |
| bool allowed; |
| char *tctx = NULL; |
| |
| if (selinux_enabled <= 0) { |
| return true; |
| } |
| |
| 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, tctx, perm, name); |
| freecon(tctx); |
| return allowed; |
| } |
| |
| static int svc_can_register(const uint16_t *name, size_t name_len, pid_t spid) |
| { |
| const char *perm = "add"; |
| return check_mac_perms_from_lookup(spid, perm, str8(name, name_len)) ? 1 : 0; |
| } |
| |
| static int svc_can_list(pid_t spid) |
| { |
| const char *perm = "list"; |
| return check_mac_perms_from_getcon(spid, perm) ? 1 : 0; |
| } |
| |
| static int svc_can_find(const uint16_t *name, size_t name_len, pid_t spid) |
| { |
| const char *perm = "find"; |
| return check_mac_perms_from_lookup(spid, 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(struct binder_state *bs, 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)) { |
| 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)) { |
| 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) { |
| struct selabel_handle *tmp_sehandle = selinux_android_service_context_handle(); |
| 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(bs, 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)) { |
| 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, security_class_t cls, char *buf, size_t len) |
| { |
| snprintf(buf, len, "service=%s", !data ? "NULL" : (char *)data); |
| return 0; |
| } |
| |
| int main(int argc, char **argv) |
| { |
| struct binder_state *bs; |
| |
| bs = binder_open(128*1024); |
| if (!bs) { |
| ALOGE("failed to open binder driver\n"); |
| return -1; |
| } |
| |
| if (binder_become_context_manager(bs)) { |
| ALOGE("cannot become context manager (%s)\n", strerror(errno)); |
| return -1; |
| } |
| |
| selinux_enabled = is_selinux_enabled(); |
| sehandle = selinux_android_service_context_handle(); |
| selinux_status_open(true); |
| |
| if (selinux_enabled > 0) { |
| 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(); |
| } |
| } |
| |
| union selinux_callback cb; |
| 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); |
| |
| binder_loop(bs, svcmgr_handler); |
| |
| return 0; |
| } |