597 lines
16 KiB
C
597 lines
16 KiB
C
/* Copyright (C) 1998-2007, 2008, 2009 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <assert.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdbool.h>
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#include <stddef.h>
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#include <string.h>
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#include <time.h>
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#include <unistd.h>
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#include <sys/mman.h>
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#include <sys/poll.h>
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#include <sys/socket.h>
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#include <sys/stat.h>
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#include <sys/time.h>
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#include <sys/uio.h>
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#include <sys/un.h>
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#include <not-cancel.h>
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#include <nis/rpcsvc/nis.h>
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#include <kernel-features.h>
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#include "nscd-client.h"
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/* Extra time we wait if the socket is still receiving data. This
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value is in milliseconds. Note that the other side is nscd on the
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local machine and it is already transmitting data. So the wait
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time need not be long. */
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#define EXTRA_RECEIVE_TIME 200
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static int
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wait_on_socket (int sock, long int usectmo)
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{
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struct pollfd fds[1];
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fds[0].fd = sock;
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fds[0].events = POLLIN | POLLERR | POLLHUP;
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int n = __poll (fds, 1, usectmo);
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if (n == -1 && __builtin_expect (errno == EINTR, 0))
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{
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/* Handle the case where the poll() call is interrupted by a
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signal. We cannot just use TEMP_FAILURE_RETRY since it might
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lead to infinite loops. */
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struct timeval now;
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(void) __gettimeofday (&now, NULL);
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long int end = now.tv_sec * 1000 + usectmo + (now.tv_usec + 500) / 1000;
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long int timeout = usectmo;
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while (1)
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{
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n = __poll (fds, 1, timeout);
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if (n != -1 || errno != EINTR)
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break;
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/* Recompute the timeout time. */
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(void) __gettimeofday (&now, NULL);
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timeout = end - (now.tv_sec * 1000 + (now.tv_usec + 500) / 1000);
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}
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}
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return n;
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}
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ssize_t
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__readall (int fd, void *buf, size_t len)
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{
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size_t n = len;
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ssize_t ret;
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do
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{
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again:
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ret = TEMP_FAILURE_RETRY (__read (fd, buf, n));
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if (ret <= 0)
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{
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if (__builtin_expect (ret < 0 && errno == EAGAIN, 0)
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/* The socket is still receiving data. Wait a bit more. */
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&& wait_on_socket (fd, EXTRA_RECEIVE_TIME) > 0)
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goto again;
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break;
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}
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buf = (char *) buf + ret;
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n -= ret;
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}
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while (n > 0);
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return ret < 0 ? ret : len - n;
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}
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ssize_t
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__readvall (int fd, const struct iovec *iov, int iovcnt)
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{
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ssize_t ret = TEMP_FAILURE_RETRY (__readv (fd, iov, iovcnt));
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if (ret <= 0)
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{
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if (__builtin_expect (ret == 0 || errno != EAGAIN, 1))
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/* A genuine error or no data to read. */
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return ret;
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/* The data has not all yet been received. Do as if we have not
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read anything yet. */
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ret = 0;
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}
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size_t total = 0;
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for (int i = 0; i < iovcnt; ++i)
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total += iov[i].iov_len;
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if (ret < total)
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{
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struct iovec iov_buf[iovcnt];
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ssize_t r = ret;
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struct iovec *iovp = memcpy (iov_buf, iov, iovcnt * sizeof (*iov));
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do
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{
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while (iovp->iov_len <= r)
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{
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r -= iovp->iov_len;
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--iovcnt;
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++iovp;
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}
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iovp->iov_base = (char *) iovp->iov_base + r;
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iovp->iov_len -= r;
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again:
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r = TEMP_FAILURE_RETRY (__readv (fd, iovp, iovcnt));
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if (r <= 0)
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{
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if (__builtin_expect (r < 0 && errno == EAGAIN, 0)
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/* The socket is still receiving data. Wait a bit more. */
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&& wait_on_socket (fd, EXTRA_RECEIVE_TIME) > 0)
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goto again;
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break;
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}
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ret += r;
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}
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while (ret < total);
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if (r < 0)
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ret = r;
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}
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return ret;
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}
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static int
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open_socket (request_type type, const char *key, size_t keylen)
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{
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int sock;
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#ifdef SOCK_CLOEXEC
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# ifndef __ASSUME_SOCK_CLOEXEC
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if (__have_sock_cloexec >= 0)
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# endif
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{
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sock = __socket (PF_UNIX, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
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# ifndef __ASSUME_SOCK_CLOEXEC
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if (__have_sock_cloexec == 0)
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__have_sock_cloexec = sock != -1 || errno != EINVAL ? 1 : -1;
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# endif
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}
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#endif
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#ifndef __ASSUME_SOCK_CLOEXEC
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# ifdef SOCK_CLOEXEC
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if (__have_sock_cloexec < 0)
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# endif
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sock = __socket (PF_UNIX, SOCK_STREAM, 0);
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#endif
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if (sock < 0)
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return -1;
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struct
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{
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request_header req;
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char key[keylen];
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} reqdata;
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size_t real_sizeof_reqdata = sizeof (request_header) + keylen;
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#ifndef __ASSUME_SOCK_CLOEXEC
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# ifdef SOCK_NONBLOCK
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if (__have_sock_cloexec < 0)
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# endif
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/* Make socket non-blocking. */
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__fcntl (sock, F_SETFL, O_RDWR | O_NONBLOCK);
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#endif
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struct sockaddr_un sun;
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sun.sun_family = AF_UNIX;
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strcpy (sun.sun_path, _PATH_NSCDSOCKET);
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if (__connect (sock, (struct sockaddr *) &sun, sizeof (sun)) < 0
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&& errno != EINPROGRESS)
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goto out;
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reqdata.req.version = NSCD_VERSION;
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reqdata.req.type = type;
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reqdata.req.key_len = keylen;
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memcpy (reqdata.key, key, keylen);
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bool first_try = true;
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struct timeval tvend;
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/* Fake initializing tvend. */
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asm ("" : "=m" (tvend));
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while (1)
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{
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#ifndef MSG_NOSIGNAL
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# define MSG_NOSIGNAL 0
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#endif
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ssize_t wres = TEMP_FAILURE_RETRY (__send (sock, &reqdata,
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real_sizeof_reqdata,
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MSG_NOSIGNAL));
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if (__builtin_expect (wres == (ssize_t) real_sizeof_reqdata, 1))
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/* We managed to send the request. */
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return sock;
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if (wres != -1 || errno != EAGAIN)
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/* Something is really wrong, no chance to continue. */
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break;
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/* The daemon is busy wait for it. */
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int to;
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struct timeval now;
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(void) __gettimeofday (&now, NULL);
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if (first_try)
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{
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tvend.tv_usec = now.tv_usec;
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tvend.tv_sec = now.tv_sec + 5;
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to = 5 * 1000;
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first_try = false;
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}
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else
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to = ((tvend.tv_sec - now.tv_sec) * 1000
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+ (tvend.tv_usec - now.tv_usec) / 1000);
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struct pollfd fds[1];
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fds[0].fd = sock;
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fds[0].events = POLLOUT | POLLERR | POLLHUP;
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if (__poll (fds, 1, to) <= 0)
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/* The connection timed out or broke down. */
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break;
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/* We try to write again. */
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}
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out:
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close_not_cancel_no_status (sock);
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return -1;
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}
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void
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__nscd_unmap (struct mapped_database *mapped)
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{
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assert (mapped->counter == 0);
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__munmap ((void *) mapped->head, mapped->mapsize);
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free (mapped);
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}
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/* Try to get a file descriptor for the shared meory segment
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containing the database. */
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struct mapped_database *
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__nscd_get_mapping (request_type type, const char *key,
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struct mapped_database **mappedp)
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{
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struct mapped_database *result = NO_MAPPING;
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#ifdef SCM_RIGHTS
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const size_t keylen = strlen (key) + 1;
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int saved_errno = errno;
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int mapfd = -1;
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char resdata[keylen];
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/* Open a socket and send the request. */
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int sock = open_socket (type, key, keylen);
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if (sock < 0)
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goto out;
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/* Room for the data sent along with the file descriptor. We expect
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the key name back. */
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uint64_t mapsize;
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struct iovec iov[2];
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iov[0].iov_base = resdata;
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iov[0].iov_len = keylen;
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iov[1].iov_base = &mapsize;
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iov[1].iov_len = sizeof (mapsize);
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union
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{
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struct cmsghdr hdr;
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char bytes[CMSG_SPACE (sizeof (int))];
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} buf;
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struct msghdr msg = { .msg_iov = iov, .msg_iovlen = 2,
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.msg_control = buf.bytes,
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.msg_controllen = sizeof (buf) };
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struct cmsghdr *cmsg = CMSG_FIRSTHDR (&msg);
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cmsg->cmsg_level = SOL_SOCKET;
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cmsg->cmsg_type = SCM_RIGHTS;
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cmsg->cmsg_len = CMSG_LEN (sizeof (int));
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/* This access is well-aligned since BUF is correctly aligned for an
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int and CMSG_DATA preserves this alignment. */
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memset (CMSG_DATA (cmsg), '\xff', sizeof (int));
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msg.msg_controllen = cmsg->cmsg_len;
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if (wait_on_socket (sock, 5 * 1000) <= 0)
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goto out_close2;
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# ifndef MSG_CMSG_CLOEXEC
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# define MSG_CMSG_CLOEXEC 0
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# endif
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ssize_t n = TEMP_FAILURE_RETRY (__recvmsg (sock, &msg, MSG_CMSG_CLOEXEC));
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if (__builtin_expect (CMSG_FIRSTHDR (&msg) == NULL
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|| (CMSG_FIRSTHDR (&msg)->cmsg_len
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!= CMSG_LEN (sizeof (int))), 0))
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goto out_close2;
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int *ip = (void *) CMSG_DATA (cmsg);
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mapfd = *ip;
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if (__builtin_expect (n != keylen && n != keylen + sizeof (mapsize), 0))
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goto out_close;
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if (__builtin_expect (strcmp (resdata, key) != 0, 0))
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goto out_close;
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if (__builtin_expect (n == keylen, 0))
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{
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struct stat64 st;
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if (__builtin_expect (fstat64 (mapfd, &st) != 0, 0)
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|| __builtin_expect (st.st_size < sizeof (struct database_pers_head),
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0))
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goto out_close;
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mapsize = st.st_size;
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}
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/* The file is large enough, map it now. */
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void *mapping = __mmap (NULL, mapsize, PROT_READ, MAP_SHARED, mapfd, 0);
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if (__builtin_expect (mapping != MAP_FAILED, 1))
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{
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/* Check whether the database is correct and up-to-date. */
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struct database_pers_head *head = mapping;
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if (__builtin_expect (head->version != DB_VERSION, 0)
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|| __builtin_expect (head->header_size != sizeof (*head), 0)
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/* Catch some misconfiguration. The server should catch
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them now but some older versions did not. */
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|| __builtin_expect (head->module == 0, 0)
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/* This really should not happen but who knows, maybe the update
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thread got stuck. */
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|| __builtin_expect (! head->nscd_certainly_running
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&& (head->timestamp + MAPPING_TIMEOUT
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< time (NULL)), 0))
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{
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out_unmap:
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__munmap (mapping, mapsize);
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goto out_close;
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}
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size_t size = (sizeof (*head) + roundup (head->module * sizeof (ref_t),
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ALIGN)
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+ head->data_size);
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if (__builtin_expect (mapsize < size, 0))
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goto out_unmap;
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/* Allocate a record for the mapping. */
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struct mapped_database *newp = malloc (sizeof (*newp));
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if (newp == NULL)
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/* Ugh, after all we went through the memory allocation failed. */
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goto out_unmap;
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newp->head = mapping;
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newp->data = ((char *) mapping + head->header_size
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+ roundup (head->module * sizeof (ref_t), ALIGN));
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newp->mapsize = size;
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newp->datasize = head->data_size;
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/* Set counter to 1 to show it is usable. */
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newp->counter = 1;
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result = newp;
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}
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out_close:
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__close (mapfd);
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out_close2:
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__close (sock);
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out:
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__set_errno (saved_errno);
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#endif /* SCM_RIGHTS */
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struct mapped_database *oldval = *mappedp;
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*mappedp = result;
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if (oldval != NULL && atomic_decrement_val (&oldval->counter) == 0)
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__nscd_unmap (oldval);
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return result;
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}
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struct mapped_database *
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__nscd_get_map_ref (request_type type, const char *name,
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volatile struct locked_map_ptr *mapptr, int *gc_cyclep)
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{
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struct mapped_database *cur = mapptr->mapped;
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if (cur == NO_MAPPING)
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return cur;
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int cnt = 0;
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while (__builtin_expect (atomic_compare_and_exchange_val_acq (&mapptr->lock,
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1, 0) != 0, 0))
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{
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// XXX Best number of rounds?
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if (__builtin_expect (++cnt > 5, 0))
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return NO_MAPPING;
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atomic_delay ();
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}
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cur = mapptr->mapped;
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if (__builtin_expect (cur != NO_MAPPING, 1))
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{
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/* If not mapped or timestamp not updated, request new map. */
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if (cur == NULL
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|| (cur->head->nscd_certainly_running == 0
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&& cur->head->timestamp + MAPPING_TIMEOUT < time (NULL))
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|| cur->head->data_size > cur->datasize)
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cur = __nscd_get_mapping (type, name,
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(struct mapped_database **) &mapptr->mapped);
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if (__builtin_expect (cur != NO_MAPPING, 1))
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{
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if (__builtin_expect (((*gc_cyclep = cur->head->gc_cycle) & 1) != 0,
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0))
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cur = NO_MAPPING;
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else
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atomic_increment (&cur->counter);
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}
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}
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mapptr->lock = 0;
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return cur;
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}
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/* Using sizeof (hashentry) is not always correct to determine the size of
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the data structure as found in the nscd cache. The program could be
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a 64-bit process and nscd could be a 32-bit process. In this case
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sizeof (hashentry) would overestimate the size. The following is
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the minimum size of such an entry, good enough for our tests here. */
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#define MINIMUM_HASHENTRY_SIZE \
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(offsetof (struct hashentry, dellist) + sizeof (int32_t))
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/* Don't return const struct datahead *, as eventhough the record
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is normally constant, it can change arbitrarily during nscd
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garbage collection. */
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struct datahead *
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__nscd_cache_search (request_type type, const char *key, size_t keylen,
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const struct mapped_database *mapped, size_t datalen)
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{
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unsigned long int hash = __nis_hash (key, keylen) % mapped->head->module;
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size_t datasize = mapped->datasize;
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ref_t trail = mapped->head->array[hash];
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trail = atomic_forced_read (trail);
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ref_t work = trail;
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size_t loop_cnt = datasize / (MINIMUM_HASHENTRY_SIZE
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+ offsetof (struct datahead, data) / 2);
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int tick = 0;
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while (work != ENDREF && work + MINIMUM_HASHENTRY_SIZE <= datasize)
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{
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struct hashentry *here = (struct hashentry *) (mapped->data + work);
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ref_t here_key, here_packet;
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#ifndef _STRING_ARCH_unaligned
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/* Although during garbage collection when moving struct hashentry
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records around we first copy from old to new location and then
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adjust pointer from previous hashentry to it, there is no barrier
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between those memory writes. It is very unlikely to hit it,
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so check alignment only if a misaligned load can crash the
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application. */
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if ((uintptr_t) here & (__alignof__ (*here) - 1))
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return NULL;
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#endif
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if (type == here->type
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&& keylen == here->len
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&& (here_key = atomic_forced_read (here->key)) + keylen <= datasize
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&& memcmp (key, mapped->data + here_key, keylen) == 0
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&& ((here_packet = atomic_forced_read (here->packet))
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|
+ sizeof (struct datahead) <= datasize))
|
|
{
|
|
/* We found the entry. Increment the appropriate counter. */
|
|
struct datahead *dh
|
|
= (struct datahead *) (mapped->data + here_packet);
|
|
|
|
#ifndef _STRING_ARCH_unaligned
|
|
if ((uintptr_t) dh & (__alignof__ (*dh) - 1))
|
|
return NULL;
|
|
#endif
|
|
|
|
/* See whether we must ignore the entry or whether something
|
|
is wrong because garbage collection is in progress. */
|
|
if (dh->usable
|
|
&& here_packet + dh->allocsize <= datasize
|
|
&& (here_packet + offsetof (struct datahead, data) + datalen
|
|
<= datasize))
|
|
return dh;
|
|
}
|
|
|
|
work = atomic_forced_read (here->next);
|
|
/* Prevent endless loops. This should never happen but perhaps
|
|
the database got corrupted, accidentally or deliberately. */
|
|
if (work == trail || loop_cnt-- == 0)
|
|
break;
|
|
if (tick)
|
|
{
|
|
struct hashentry *trailelem;
|
|
trailelem = (struct hashentry *) (mapped->data + trail);
|
|
|
|
#ifndef _STRING_ARCH_unaligned
|
|
/* We have to redo the checks. Maybe the data changed. */
|
|
if ((uintptr_t) trailelem & (__alignof__ (*trailelem) - 1))
|
|
return NULL;
|
|
#endif
|
|
|
|
if (trail + MINIMUM_HASHENTRY_SIZE > datasize)
|
|
return NULL;
|
|
|
|
trail = atomic_forced_read (trailelem->next);
|
|
}
|
|
tick = 1 - tick;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
|
|
/* Create a socket connected to a name. */
|
|
int
|
|
__nscd_open_socket (const char *key, size_t keylen, request_type type,
|
|
void *response, size_t responselen)
|
|
{
|
|
/* This should never happen and it is something the nscd daemon
|
|
enforces, too. He it helps to limit the amount of stack
|
|
used. */
|
|
if (keylen > MAXKEYLEN)
|
|
return -1;
|
|
|
|
int saved_errno = errno;
|
|
|
|
int sock = open_socket (type, key, keylen);
|
|
if (sock >= 0)
|
|
{
|
|
/* Wait for data. */
|
|
if (wait_on_socket (sock, 5 * 1000) > 0)
|
|
{
|
|
ssize_t nbytes = TEMP_FAILURE_RETRY (__read (sock, response,
|
|
responselen));
|
|
if (nbytes == (ssize_t) responselen)
|
|
return sock;
|
|
}
|
|
|
|
close_not_cancel_no_status (sock);
|
|
}
|
|
|
|
__set_errno (saved_errno);
|
|
|
|
return -1;
|
|
}
|