diff options
Diffstat (limited to 'ex.c')
| -rw-r--r-- | ex.c | 293 |
1 files changed, 293 insertions, 0 deletions
@@ -0,0 +1,293 @@ +/* + * Copyright (c) 2021 Omar Polo <op@omarpolo.com> + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +#include <err.h> +#include <errno.h> + +#include <fcntl.h> +#include <signal.h> +#include <string.h> + +#include "gmid.h" + +int +send_string(int fd, const char *str) +{ + ssize_t len; + + if (str == NULL) + len = 0; + else + len = strlen(str); + + if (write(fd, &len, sizeof(len)) != sizeof(len)) + return 0; + + if (len != 0) + if (write(fd, str, len) != len) + return 0; + + return 1; +} + +int +recv_string(int fd, char **ret) +{ + ssize_t len; + + if (read(fd, &len, sizeof(len)) != sizeof(len)) + return 0; + + if (len == 0) { + *ret = NULL; + return 1; + } + + if ((*ret = calloc(1, len+1)) == NULL) + return 0; + + if (read(fd, *ret, len) != len) + return 0; + return 1; +} + +int +send_vhost(int fd, struct vhost *vhost) +{ + ssize_t n; + + if (vhost < hosts || vhost > hosts + HOSTSLEN) + return 0; + + n = hosts - vhost; + return write(fd, &n, sizeof(n)) == sizeof(n); +} + +int +recv_vhost(int fd, struct vhost **vhost) +{ + ssize_t n; + + if (read(fd, &n, sizeof(n)) != sizeof(n)) + return 0; + + if (n < 0 || n > HOSTSLEN) + return 0; + + *vhost = &hosts[n]; + if ((*vhost)->domain == NULL) + return 0; + return 1; +} + +/* send d though fd. see /usr/src/usr.sbin/syslogd/privsep_fdpass.c + * for an example */ +int +send_fd(int fd, int d) +{ + struct msghdr msg; + union { + struct cmsghdr hdr; + unsigned char buf[CMSG_SPACE(sizeof(int))]; + } cmsgbuf; + struct cmsghdr *cmsg; + struct iovec vec; + int result = 1; + ssize_t n; + + memset(&msg, 0, sizeof(msg)); + + if (d >= 0) { + msg.msg_control = &cmsgbuf.buf; + msg.msg_controllen = sizeof(cmsgbuf.buf); + cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_len = CMSG_LEN(sizeof(int)); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + *(int*)CMSG_DATA(cmsg) = d; + } else + result = 0; + + vec.iov_base = &result; + vec.iov_len = sizeof(int); + msg.msg_iov = &vec; + msg.msg_iovlen = 1; + + if ((n = sendmsg(fd, &msg, 0)) == -1 || n != sizeof(int)) { + fprintf(stderr, "sendmsg: got %zu but wanted %zu: (errno) %s", + n, sizeof(int), strerror(errno)); + return 0; + } + return 1; +} + +/* receive a descriptor via fd */ +int +recv_fd(int fd) +{ + struct msghdr msg; + union { + struct cmsghdr hdr; + char buf[CMSG_SPACE(sizeof(int))]; + } cmsgbuf; + struct cmsghdr *cmsg; + struct iovec vec; + ssize_t n; + int result; + + memset(&msg, 0, sizeof(msg)); + vec.iov_base = &result; + vec.iov_len = sizeof(int); + msg.msg_iov = &vec; + msg.msg_iovlen = 1; + msg.msg_control = &cmsgbuf.buf; + msg.msg_controllen = sizeof(cmsgbuf.buf); + + if ((n = recvmsg(fd, &msg, 0)) != sizeof(int)) { + fprintf(stderr, "read %zu bytes bu wanted %zu\n", n, sizeof(int)); + return -1; + } + + if (result) { + cmsg = CMSG_FIRSTHDR(&msg); + if (cmsg == NULL || cmsg->cmsg_type != SCM_RIGHTS) + return -1; + return (*(int *)CMSG_DATA(cmsg)); + } else + return -1; +} + +static inline void +safe_setenv(const char *name, const char *val) +{ + if (val == NULL) + val = ""; + setenv(name, val, 1); +} + +/* fd or -1 on error */ +static int +launch_cgi(const char *spath, const char *relpath, const char *query, + const char *addr, const char *ruser, const char *cissuer, const char *chash, + struct vhost *vhost) +{ + int p[2]; /* read end, write end */ + + if (pipe2(p, O_NONBLOCK) == -1) + return -1; + + switch (fork()) { + case -1: + return -1; + + case 0: { /* child */ + char *portno, *ex, *requri; + char *argv[] = { NULL, NULL, NULL }; + + close(p[0]); + if (dup2(p[1], 1) == -1) + goto childerr; + + if (asprintf(&portno, "%d", conf.port) == -1) + goto childerr; + + if (asprintf(&ex, "%s/%s", vhost->dir, spath) == -1) + goto childerr; + + if (asprintf(&requri, "%s%s%s", spath, + (relpath != NULL && *relpath == '\0') ? "" : "/", relpath) == -1) + goto childerr; + + argv[0] = argv[1] = ex; + + safe_setenv("GATEWAY_INTERFACE", "CGI/1.1"); + safe_setenv("SERVER_SOFTWARE", "gmid"); + safe_setenv("SERVER_PORT", portno); + + if (!strcmp(vhost->domain, "*")) + safe_setenv("SERVER_NAME", vhost->domain); + + safe_setenv("SCRIPT_NAME", spath); + safe_setenv("SCRIPT_EXECUTABLE", ex); + safe_setenv("REQUEST_URI", requri); + safe_setenv("REQUEST_RELATIVE", relpath); + safe_setenv("QUERY_STRING", query); + safe_setenv("REMOTE_HOST", addr); + safe_setenv("REMOTE_ADDR", addr); + safe_setenv("DOCUMENT_ROOT", vhost->dir); + + if (ruser != NULL) { + safe_setenv("AUTH_TYPE", "Certificate"); + safe_setenv("REMOTE_USER", ruser); + safe_setenv("TLS_CLIENT_ISSUER", cissuer); + safe_setenv("TLS_CLIENT_HASH", chash); + } + + execvp(ex, argv); + goto childerr; + } + + default: + close(p[1]); + return p[0]; + } + +childerr: + dprintf(p[1], "%d internal server error\r\n", TEMP_FAILURE); + _exit(1); +} + +int +executor_main(int fd) +{ + char *spath, *relpath, *query, *addr, *ruser, *cissuer, *chash; + struct vhost *vhost; + int d; + +#ifdef __OpenBSD__ + pledge("stdio sendfd proc exec", NULL); +#endif + + for (;;) { + if (!recv_string(fd, &spath) + || !recv_string(fd, &relpath) + || !recv_string(fd, &query) + || !recv_string(fd, &addr) + || !recv_string(fd, &ruser) + || !recv_string(fd, &cissuer) + || !recv_string(fd, &chash) + || !recv_vhost(fd, &vhost)) + break; + + d = launch_cgi(spath, relpath, query, + addr, ruser, cissuer, chash, vhost); + if (!send_fd(fd, d)) + break; + + free(spath); + free(relpath); + free(query); + free(addr); + free(ruser); + free(cissuer); + free(chash); + } + + /* kill all process in my group. This means the listener and + * every pending CGI script. */ + kill(0, SIGINT); + return 1; +} |