1 files changed, 694 insertions, 0 deletions
diff --git a/privops.c b/privops.c
new file mode 100644
index 0000000..9870717
--- /dev/null
+++ b/privops.c
@@ -0,0 +1,694 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Bryan Christianson 2015
+ * Copyright (C) Miroslav Lichvar  2017
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Perform privileged operations over a unix socket to a privileged fork.
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include "conf.h"
+#include "nameserv.h"
+#include "logging.h"
+#include "privops.h"
+#include "socket.h"
+#include "util.h"
+
+#define OP_ADJUSTTIME     1024
+#define OP_ADJUSTTIMEX    1025
+#define OP_SETTIME        1026
+#define OP_BINDSOCKET     1027
+#define OP_NAME2IPADDRESS 1028
+#define OP_RELOADDNS      1029
+#define OP_QUIT           1099
+
+union sockaddr_in46 {
+  struct sockaddr_in in4;
+#ifdef FEAT_IPV6
+  struct sockaddr_in6 in6;
+#endif
+  struct sockaddr u;
+};
+
+/* daemon request structs */
+
+typedef struct {
+  struct timeval tv;
+} ReqAdjustTime;
+
+#ifdef PRIVOPS_ADJUSTTIMEX
+typedef struct {
+  struct timex tmx;
+} ReqAdjustTimex;
+#endif
+
+typedef struct {
+  struct timeval tv;
+} ReqSetTime;
+
+typedef struct {
+  int sock;
+  socklen_t sa_len;
+  union sockaddr_in46 sa;
+} ReqBindSocket;
+
+typedef struct {
+  char name[256];
+} ReqName2IPAddress;
+
+typedef struct {
+  int op;
+  union {
+    ReqAdjustTime adjust_time;
+#ifdef PRIVOPS_ADJUSTTIMEX
+    ReqAdjustTimex adjust_timex;
+#endif
+    ReqSetTime set_time;
+    ReqBindSocket bind_socket;
+#ifdef PRIVOPS_NAME2IPADDRESS
+    ReqName2IPAddress name_to_ipaddress;
+#endif
+  } data;
+} PrvRequest;
+
+/* helper response structs */
+
+typedef struct {
+  struct timeval tv;
+} ResAdjustTime;
+
+#ifdef PRIVOPS_ADJUSTTIMEX
+typedef struct {
+  struct timex tmx;
+} ResAdjustTimex;
+#endif
+
+typedef struct {
+  IPAddr addresses[DNS_MAX_ADDRESSES];
+} ResName2IPAddress;
+
+typedef struct {
+  char msg[256];
+} ResFatalMsg;
+
+typedef struct {
+  int fatal_error;
+  int rc;
+  int res_errno;
+  union {
+    ResFatalMsg fatal_msg;
+    ResAdjustTime adjust_time;
+#ifdef PRIVOPS_ADJUSTTIMEX
+    ResAdjustTimex adjust_timex;
+#endif
+#ifdef PRIVOPS_NAME2IPADDRESS
+    ResName2IPAddress name_to_ipaddress;
+#endif
+  } data;
+} PrvResponse;
+
+static int helper_fd;
+static pid_t helper_pid;
+
+static int
+have_helper(void)
+{
+  return helper_fd >= 0;
+}
+
+/* ======================================================================= */
+
+/* HELPER - prepare fatal error for daemon */
+static void
+res_fatal(PrvResponse *res, const char *fmt, ...)
+{
+  va_list ap;
+
+  res->fatal_error = 1;
+  va_start(ap, fmt);
+  vsnprintf(res->data.fatal_msg.msg, sizeof (res->data.fatal_msg.msg), fmt, ap);
+  va_end(ap);
+}
+
+/* ======================================================================= */
+
+/* HELPER - send response to the fd */
+
+static int
+send_response(int fd, const PrvResponse *res)
+{
+  if (SCK_Send(fd, res, sizeof (*res), 0) != sizeof (*res))
+    return 0;
+
+  return 1;
+}
+
+/* ======================================================================= */
+/* receive daemon request plus optional file descriptor over a unix socket */
+
+static int
+receive_from_daemon(int fd, PrvRequest *req)
+{
+  SCK_Message *message;
+
+  message = SCK_ReceiveMessage(fd, SCK_FLAG_MSG_DESCRIPTOR);
+  if (!message || message->length != sizeof (*req))
+    return 0;
+
+  memcpy(req, message->data, sizeof (*req));
+
+  if (req->op == OP_BINDSOCKET) {
+    req->data.bind_socket.sock = message->descriptor;
+
+    /* return error if valid descriptor not found */
+    if (req->data.bind_socket.sock < 0)
+      return 0;
+  } else if (message->descriptor >= 0) {
+    SCK_CloseSocket(message->descriptor);
+    return 0;
+  }
+
+  return 1;
+}
+
+/* ======================================================================= */
+
+/* HELPER - perform adjtime() */
+
+#ifdef PRIVOPS_ADJUSTTIME
+static void
+do_adjust_time(const ReqAdjustTime *req, PrvResponse *res)
+{
+  res->rc = adjtime(&req->tv, &res->data.adjust_time.tv);
+  if (res->rc)
+    res->res_errno = errno;
+}
+#endif
+
+/* ======================================================================= */
+
+/* HELPER - perform ntp_adjtime() */
+
+#ifdef PRIVOPS_ADJUSTTIMEX
+static void
+do_adjust_timex(const ReqAdjustTimex *req, PrvResponse *res)
+{
+  res->data.adjust_timex.tmx = req->tmx;
+  res->rc = ntp_adjtime(&res->data.adjust_timex.tmx);
+  if (res->rc < 0)
+    res->res_errno = errno;
+}
+#endif
+
+/* ======================================================================= */
+
+/* HELPER - perform settimeofday() */
+
+#ifdef PRIVOPS_SETTIME
+static void
+do_set_time(const ReqSetTime *req, PrvResponse *res)
+{
+  res->rc = settimeofday(&req->tv, NULL);
+  if (res->rc)
+    res->res_errno = errno;
+}
+#endif
+
+/* ======================================================================= */
+
+/* HELPER - perform bind() */
+
+#ifdef PRIVOPS_BINDSOCKET
+static void
+do_bind_socket(ReqBindSocket *req, PrvResponse *res)
+{
+  IPSockAddr ip_saddr;
+  int sock_fd;
+  struct sockaddr *sa;
+  socklen_t sa_len;
+
+  sa = &req->sa.u;
+  sa_len = req->sa_len;
+  sock_fd = req->sock;
+
+  SCK_SockaddrToIPSockAddr(sa, sa_len, &ip_saddr);
+  if (ip_saddr.port != 0 && ip_saddr.port != CNF_GetNTPPort() &&
+      ip_saddr.port != CNF_GetAcquisitionPort()) {
+    SCK_CloseSocket(sock_fd);
+    res_fatal(res, "Invalid port %d", ip_saddr.port);
+    return;
+  }
+
+  res->rc = bind(sock_fd, sa, sa_len);
+  if (res->rc)
+    res->res_errno = errno;
+
+  /* sock is still open on daemon side, but we're done with it in the helper */
+  SCK_CloseSocket(sock_fd);
+}
+#endif
+
+/* ======================================================================= */
+
+/* HELPER - perform DNS_Name2IPAddress() */
+
+#ifdef PRIVOPS_NAME2IPADDRESS
+static void
+do_name_to_ipaddress(ReqName2IPAddress *req, PrvResponse *res)
+{
+  /* make sure the string is terminated */
+  req->name[sizeof (req->name) - 1] = '\0';
+
+  res->rc = DNS_Name2IPAddress(req->name, res->data.name_to_ipaddress.addresses,
+                               DNS_MAX_ADDRESSES);
+}
+#endif
+
+/* ======================================================================= */
+
+/* HELPER - perform DNS_Reload() */
+
+#ifdef PRIVOPS_RELOADDNS
+static void
+do_reload_dns(PrvResponse *res)
+{
+  DNS_Reload();
+  res->rc = 0;
+}
+#endif
+
+/* ======================================================================= */
+
+/* HELPER - main loop - action requests from the daemon */
+
+static void
+helper_main(int fd)
+{
+  PrvRequest req;
+  PrvResponse res;
+  int quit = 0;
+
+  while (!quit) {
+    if (!receive_from_daemon(fd, &req))
+      /* read error or closed input - we cannot recover - give up */
+      break;
+
+    memset(&res, 0, sizeof (res));
+
+    switch (req.op) {
+#ifdef PRIVOPS_ADJUSTTIME
+      case OP_ADJUSTTIME:
+        do_adjust_time(&req.data.adjust_time, &res);
+        break;
+#endif
+#ifdef PRIVOPS_ADJUSTTIMEX
+      case OP_ADJUSTTIMEX:
+        do_adjust_timex(&req.data.adjust_timex, &res);
+        break;
+#endif
+#ifdef PRIVOPS_SETTIME
+      case OP_SETTIME:
+        do_set_time(&req.data.set_time, &res);
+        break;
+#endif
+#ifdef PRIVOPS_BINDSOCKET
+      case OP_BINDSOCKET:
+        do_bind_socket(&req.data.bind_socket, &res);
+        break;
+#endif
+#ifdef PRIVOPS_NAME2IPADDRESS
+      case OP_NAME2IPADDRESS:
+        do_name_to_ipaddress(&req.data.name_to_ipaddress, &res);
+        break;
+#endif
+#ifdef PRIVOPS_RELOADDNS
+      case OP_RELOADDNS:
+        do_reload_dns(&res);
+        break;
+#endif
+      case OP_QUIT:
+        quit = 1;
+        continue;
+
+      default:
+        res_fatal(&res, "Unexpected operator %d", req.op);
+        break;
+    }
+
+    send_response(fd, &res);
+  }
+
+  SCK_CloseSocket(fd);
+  exit(0);
+}
+
+/* ======================================================================= */
+
+/* DAEMON - receive helper response */
+
+static void
+receive_response(PrvResponse *res)
+{
+  int resp_len;
+
+  resp_len = SCK_Receive(helper_fd, res, sizeof (*res), 0);
+  if (resp_len < 0)
+    LOG_FATAL("Could not read from helper : %s", strerror(errno));
+  if (resp_len != sizeof (*res))
+    LOG_FATAL("Invalid helper response");
+
+  if (res->fatal_error)
+    LOG_FATAL("Error in helper : %s", res->data.fatal_msg.msg);
+
+  DEBUG_LOG("Received response rc=%d", res->rc);
+
+  /* if operation failed in the helper, set errno so daemon can print log message */
+  if (res->res_errno)
+    errno = res->res_errno;
+}
+
+/* ======================================================================= */
+
+/* DAEMON - send daemon request to the helper */
+
+static void
+send_request(PrvRequest *req)
+{
+  SCK_Message message;
+  int flags;
+
+  SCK_InitMessage(&message, SCK_ADDR_UNSPEC);
+
+  message.data = req;
+  message.length = sizeof (*req);
+  flags = 0;
+
+  if (req->op == OP_BINDSOCKET) {
+    /* send file descriptor as a control message */
+    message.descriptor = req->data.bind_socket.sock;
+    flags |= SCK_FLAG_MSG_DESCRIPTOR;
+  }
+
+  if (!SCK_SendMessage(helper_fd, &message, flags)) {
+    /* don't try to send another request from exit() */
+    helper_fd = -1;
+    LOG_FATAL("Could not send to helper : %s", strerror(errno));
+  }
+
+  DEBUG_LOG("Sent request op=%d", req->op);
+}
+
+/* ======================================================================= */
+
+/* DAEMON - send daemon request and wait for response */
+
+static void
+submit_request(PrvRequest *req, PrvResponse *res)
+{
+  send_request(req);
+  receive_response(res);
+}
+
+/* ======================================================================= */
+
+/* DAEMON - send the helper a request to exit and wait until it exits */
+
+static void
+stop_helper(void)
+{
+  PrvRequest req;
+  int status;
+
+  if (!have_helper())
+    return;
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_QUIT;
+  send_request(&req);
+
+  waitpid(helper_pid, &status, 0);
+}
+
+/* ======================================================================= */
+
+/* DAEMON - request adjtime() */
+
+#ifdef PRIVOPS_ADJUSTTIME
+int
+PRV_AdjustTime(const struct timeval *delta, struct timeval *olddelta)
+{
+  PrvRequest req;
+  PrvResponse res;
+
+  if (!have_helper() || delta == NULL)
+    /* helper is not running or read adjustment call */
+    return adjtime(delta, olddelta);
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_ADJUSTTIME;
+  req.data.adjust_time.tv = *delta;
+
+  submit_request(&req, &res);
+
+  if (olddelta)
+    *olddelta = res.data.adjust_time.tv;
+
+  return res.rc;
+}
+#endif
+
+/* ======================================================================= */
+
+/* DAEMON - request ntp_adjtime() */
+
+#ifdef PRIVOPS_ADJUSTTIMEX
+int
+PRV_AdjustTimex(struct timex *tmx)
+{
+  PrvRequest req;
+  PrvResponse res;
+
+  if (!have_helper())
+    return ntp_adjtime(tmx);
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_ADJUSTTIMEX;
+  req.data.adjust_timex.tmx = *tmx;
+
+  submit_request(&req, &res);
+
+  *tmx = res.data.adjust_timex.tmx;
+
+  return res.rc;
+}
+#endif
+
+/* ======================================================================= */
+
+/* DAEMON - request settimeofday() */
+
+#ifdef PRIVOPS_SETTIME
+int
+PRV_SetTime(const struct timeval *tp, const struct timezone *tzp)
+{
+  PrvRequest req;
+  PrvResponse res;
+
+  /* only support setting the time */
+  assert(tp != NULL);
+  assert(tzp == NULL);
+
+  if (!have_helper())
+    return settimeofday(tp, NULL);
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_SETTIME;
+  req.data.set_time.tv = *tp;
+
+  submit_request(&req, &res);
+
+  return res.rc;
+}
+#endif
+
+/* ======================================================================= */
+
+/* DAEMON - request bind() */
+
+#ifdef PRIVOPS_BINDSOCKET
+int
+PRV_BindSocket(int sock, struct sockaddr *address, socklen_t address_len)
+{
+  IPSockAddr ip_saddr;
+  PrvRequest req;
+  PrvResponse res;
+
+  SCK_SockaddrToIPSockAddr(address, address_len, &ip_saddr);
+  if (ip_saddr.port != 0 && ip_saddr.port != CNF_GetNTPPort() &&
+      ip_saddr.port != CNF_GetAcquisitionPort())
+    assert(0);
+
+  if (!have_helper())
+    return bind(sock, address, address_len);
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_BINDSOCKET;
+  req.data.bind_socket.sock = sock;
+  req.data.bind_socket.sa_len = address_len;
+  assert(address_len <= sizeof (req.data.bind_socket.sa));
+  memcpy(&req.data.bind_socket.sa.u, address, address_len);
+
+  submit_request(&req, &res);
+
+  return res.rc;
+}
+#endif
+
+/* ======================================================================= */
+
+/* DAEMON - request DNS_Name2IPAddress() */
+
+#ifdef PRIVOPS_NAME2IPADDRESS
+int
+PRV_Name2IPAddress(const char *name, IPAddr *ip_addrs, int max_addrs)
+{
+  PrvRequest req;
+  PrvResponse res;
+  int i;
+
+  if (!have_helper())
+    return DNS_Name2IPAddress(name, ip_addrs, max_addrs);
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_NAME2IPADDRESS;
+  if (snprintf(req.data.name_to_ipaddress.name, sizeof (req.data.name_to_ipaddress.name),
+               "%s", name) >= sizeof (req.data.name_to_ipaddress.name)) {
+    return DNS_Failure;
+  }
+
+  submit_request(&req, &res);
+
+  for (i = 0; i < max_addrs && i < DNS_MAX_ADDRESSES; i++)
+    ip_addrs[i] = res.data.name_to_ipaddress.addresses[i];
+
+  return res.rc;
+}
+#endif
+
+/* ======================================================================= */
+
+/* DAEMON - request res_init() */
+
+#ifdef PRIVOPS_RELOADDNS
+void
+PRV_ReloadDNS(void)
+{
+  PrvRequest req;
+  PrvResponse res;
+
+  if (!have_helper()) {
+    DNS_Reload();
+    return;
+  }
+
+  memset(&req, 0, sizeof (req));
+  req.op = OP_RELOADDNS;
+
+  submit_request(&req, &res);
+  assert(!res.rc);
+}
+#endif
+
+/* ======================================================================= */
+
+void
+PRV_Initialise(void)
+{
+  helper_fd = -1;
+}
+
+/* ======================================================================= */
+
+/* DAEMON - setup socket(s) then fork to run the helper */
+/* must be called before privileges are dropped */
+
+void
+PRV_StartHelper(void)
+{
+  pid_t pid;
+  int fd, sock_fd1, sock_fd2;
+
+  if (have_helper())
+    LOG_FATAL("Helper already running");
+
+  sock_fd1 = SCK_OpenUnixSocketPair(SCK_FLAG_BLOCK, &sock_fd2);
+  if (sock_fd1 < 0)
+    LOG_FATAL("Could not open socket pair");
+
+  pid = fork();
+  if (pid < 0)
+    LOG_FATAL("fork() failed : %s", strerror(errno));
+
+  if (pid == 0) {
+    /* child process */
+    SCK_CloseSocket(sock_fd1);
+
+    /* close other descriptors inherited from the parent process, except
+       stdin, stdout, and stderr */
+    for (fd = STDERR_FILENO + 1; fd < 1024; fd++) {
+      if (fd != sock_fd2)
+        close(fd);
+    }
+
+    /* ignore signals, the process will exit on OP_QUIT request */
+    UTI_SetQuitSignalsHandler(SIG_IGN, 1);
+
+    helper_main(sock_fd2);
+
+  } else {
+    /* parent process */
+    SCK_CloseSocket(sock_fd2);
+    helper_fd = sock_fd1;
+    helper_pid = pid;
+
+    /* stop the helper even when not exiting cleanly from the main function */
+    atexit(stop_helper);
+  }
+}
+
+/* ======================================================================= */
+
+/* DAEMON - graceful shutdown of the helper */
+
+void
+PRV_Finalise(void)
+{
+  if (!have_helper())
+    return;
+
+  stop_helper();
+  close(helper_fd);
+  helper_fd = -1;
+}