/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ /*** This file is part of systemd. Copyright 2010 Lennart Poettering systemd is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>. ***/ #include <sys/socket.h> #include <sys/un.h> #include <sys/types.h> #include <fcntl.h> #include <unistd.h> #include <string.h> #include <errno.h> #include <sys/epoll.h> #include <stddef.h> #include "log.h" #include "util.h" #include "socket-util.h" #define BUFFER_SIZE (64*1024) #define EXTRA_SIZE 16 static bool initial_nul = false; static bool auth_over = false; static void format_uid(char *buf, size_t l) { char text[20 + 1]; /* enough space for a 64bit integer plus NUL */ unsigned j; assert(l > 0); snprintf(text, sizeof(text)-1, "%llu", (unsigned long long) geteuid()); text[sizeof(text)-1] = 0; memset(buf, 0, l); for (j = 0; text[j] && j*2+2 < l; j++) { buf[j*2] = hexchar(text[j] >> 4); buf[j*2+1] = hexchar(text[j] & 0xF); } buf[j*2] = 0; } static size_t patch_in_line(char *line, size_t l, size_t left) { size_t r; if (line[0] == 0 && !initial_nul) { initial_nul = true; line += 1; l -= 1; r = 1; } else r = 0; if (l == 5 && strncmp(line, "BEGIN", 5) == 0) { r += l; auth_over = true; } else if (l == 17 && strncmp(line, "NEGOTIATE_UNIX_FD", 17) == 0) { memmove(line + 13, line + 17, left); memcpy(line, "NEGOTIATE_NOP", 13); r += 13; } else if (l >= 14 && strncmp(line, "AUTH EXTERNAL ", 14) == 0) { char uid[20*2 + 1]; size_t len; format_uid(uid, sizeof(uid)); len = strlen(uid); assert(len <= EXTRA_SIZE); memmove(line + 14 + len, line + l, left); memcpy(line + 14, uid, len); r += 14 + len; } else r += l; return r; } static size_t patch_in_buffer(char* in_buffer, size_t *in_buffer_full) { size_t i, good = 0; if (*in_buffer_full <= 0) return *in_buffer_full; /* If authentication is done, we don't touch anything anymore */ if (auth_over) return *in_buffer_full; if (*in_buffer_full < 2) return 0; for (i = 0; i <= *in_buffer_full - 2; i ++) { /* Fully lines can be send on */ if (in_buffer[i] == '\r' && in_buffer[i+1] == '\n') { if (i > good) { size_t old_length, new_length; old_length = i - good; new_length = patch_in_line(in_buffer+good, old_length, *in_buffer_full - i); *in_buffer_full = *in_buffer_full + new_length - old_length; good += new_length + 2; } else good = i+2; } if (auth_over) break; } return good; } int main(int argc, char *argv[]) { int r = EXIT_FAILURE, fd = -1, ep = -1; union sockaddr_union sa; char in_buffer[BUFFER_SIZE+EXTRA_SIZE], out_buffer[BUFFER_SIZE+EXTRA_SIZE]; size_t in_buffer_full = 0, out_buffer_full = 0; struct epoll_event stdin_ev, stdout_ev, fd_ev; bool stdin_readable = false, stdout_writable = false, fd_readable = false, fd_writable = false; bool stdin_rhup = false, stdout_whup = false, fd_rhup = false, fd_whup = false; if (argc > 1) { log_error("This program takes no argument."); return EXIT_FAILURE; } log_set_target(LOG_TARGET_SYSLOG_OR_KMSG); log_parse_environment(); log_open(); if ((fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0)) < 0) { log_error("Failed to create socket: %s", strerror(errno)); goto finish; } zero(sa); sa.un.sun_family = AF_UNIX; strncpy(sa.un.sun_path, "/run/dbus/system_bus_socket", sizeof(sa.un.sun_path)); if (connect(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + 1 + strlen(sa.un.sun_path+1)) < 0) { log_error("Failed to connect: %m"); goto finish; } fd_nonblock(STDIN_FILENO, 1); fd_nonblock(STDOUT_FILENO, 1); if ((ep = epoll_create1(EPOLL_CLOEXEC)) < 0) { log_error("Failed to create epoll: %m"); goto finish; } zero(stdin_ev); stdin_ev.events = EPOLLIN|EPOLLET; stdin_ev.data.fd = STDIN_FILENO; zero(stdout_ev); stdout_ev.events = EPOLLOUT|EPOLLET; stdout_ev.data.fd = STDOUT_FILENO; zero(fd_ev); fd_ev.events = EPOLLIN|EPOLLOUT|EPOLLET; fd_ev.data.fd = fd; if (epoll_ctl(ep, EPOLL_CTL_ADD, STDIN_FILENO, &stdin_ev) < 0 || epoll_ctl(ep, EPOLL_CTL_ADD, STDOUT_FILENO, &stdout_ev) < 0 || epoll_ctl(ep, EPOLL_CTL_ADD, fd, &fd_ev) < 0) { log_error("Failed to regiser fds in epoll: %m"); goto finish; } do { struct epoll_event ev[16]; ssize_t k; int i, nfds; if ((nfds = epoll_wait(ep, ev, ELEMENTSOF(ev), -1)) < 0) { if (errno == EINTR || errno == EAGAIN) continue; log_error("epoll_wait(): %m"); goto finish; } assert(nfds >= 1); for (i = 0; i < nfds; i++) { if (ev[i].data.fd == STDIN_FILENO) { if (!stdin_rhup && (ev[i].events & (EPOLLHUP|EPOLLIN))) stdin_readable = true; } else if (ev[i].data.fd == STDOUT_FILENO) { if (ev[i].events & EPOLLHUP) { stdout_writable = false; stdout_whup = true; } if (!stdout_whup && (ev[i].events & EPOLLOUT)) stdout_writable = true; } else if (ev[i].data.fd == fd) { if (ev[i].events & EPOLLHUP) { fd_writable = false; fd_whup = true; } if (!fd_rhup && (ev[i].events & (EPOLLHUP|EPOLLIN))) fd_readable = true; if (!fd_whup && (ev[i].events & EPOLLOUT)) fd_writable = true; } } while ((stdin_readable && in_buffer_full <= 0) || (fd_writable && patch_in_buffer(in_buffer, &in_buffer_full) > 0) || (fd_readable && out_buffer_full <= 0) || (stdout_writable && out_buffer_full > 0)) { size_t in_buffer_good = 0; if (stdin_readable && in_buffer_full < BUFFER_SIZE) { if ((k = read(STDIN_FILENO, in_buffer + in_buffer_full, BUFFER_SIZE - in_buffer_full)) < 0) { if (errno == EAGAIN) stdin_readable = false; else if (errno == EPIPE || errno == ECONNRESET) k = 0; else { log_error("read(): %m"); goto finish; } } else in_buffer_full += (size_t) k; if (k == 0) { stdin_rhup = true; stdin_readable = false; shutdown(STDIN_FILENO, SHUT_RD); close_nointr_nofail(STDIN_FILENO); } } in_buffer_good = patch_in_buffer(in_buffer, &in_buffer_full); if (fd_writable && in_buffer_good > 0) { if ((k = write(fd, in_buffer, in_buffer_good)) < 0) { if (errno == EAGAIN) fd_writable = false; else if (errno == EPIPE || errno == ECONNRESET) { fd_whup = true; fd_writable = false; shutdown(fd, SHUT_WR); } else { log_error("write(): %m"); goto finish; } } else { assert(in_buffer_full >= (size_t) k); memmove(in_buffer, in_buffer + k, in_buffer_full - k); in_buffer_full -= k; } } if (fd_readable && out_buffer_full < BUFFER_SIZE) { if ((k = read(fd, out_buffer + out_buffer_full, BUFFER_SIZE - out_buffer_full)) < 0) { if (errno == EAGAIN) fd_readable = false; else if (errno == EPIPE || errno == ECONNRESET) k = 0; else { log_error("read(): %m"); goto finish; } } else out_buffer_full += (size_t) k; if (k == 0) { fd_rhup = true; fd_readable = false; shutdown(fd, SHUT_RD); } } if (stdout_writable && out_buffer_full > 0) { if ((k = write(STDOUT_FILENO, out_buffer, out_buffer_full)) < 0) { if (errno == EAGAIN) stdout_writable = false; else if (errno == EPIPE || errno == ECONNRESET) { stdout_whup = true; stdout_writable = false; shutdown(STDOUT_FILENO, SHUT_WR); close_nointr(STDOUT_FILENO); } else { log_error("write(): %m"); goto finish; } } else { assert(out_buffer_full >= (size_t) k); memmove(out_buffer, out_buffer + k, out_buffer_full - k); out_buffer_full -= k; } } } if (stdin_rhup && in_buffer_full <= 0 && !fd_whup) { fd_whup = true; fd_writable = false; shutdown(fd, SHUT_WR); } if (fd_rhup && out_buffer_full <= 0 && !stdout_whup) { stdout_whup = true; stdout_writable = false; shutdown(STDOUT_FILENO, SHUT_WR); close_nointr(STDOUT_FILENO); } } while (!stdout_whup || !fd_whup); r = EXIT_SUCCESS; finish: if (fd >= 0) close_nointr_nofail(fd); if (ep >= 0) close_nointr_nofail(ep); return r; }