/*      $OpenBSD: proc.c,v 1.36 2025/08/14 10:50:08 jsg Exp $   */

/*
 * Copyright (c) 2010 - 2016 Reyk Floeter <reyk@openbsd.org>
 * Copyright (c) 2008 Pierre-Yves Ritschard <pyr@openbsd.org>
 *
 * 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 <sys/types.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/wait.h>

#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <signal.h>
#include <pwd.h>
#include <event.h>
#include <imsg.h>
#include <ctype.h>

#include "proc.h"

void     proc_exec(struct privsep *, struct privsep_proc *, unsigned int, int,
            char **);
void     proc_setup(struct privsep *, struct privsep_proc *, unsigned int);
void     proc_accept(struct privsep *, int, enum privsep_procid);
void     proc_close(struct privsep *);
void     proc_shutdown(struct privsep_proc *);
void     proc_sig_handler(int, short, void *);
int      proc_dispatch_null(int, struct privsep_proc *, struct imsg *);

enum privsep_procid
proc_getid(struct privsep_proc *procs, unsigned int nproc,
    const char *proc_name)
{
        struct privsep_proc     *p;
        unsigned int             proc;

        for (proc = 0; proc < nproc; proc++) {
                p = &procs[proc];
                if (strcmp(p->p_title, proc_name))
                        continue;

                return (p->p_id);
        }

        return (PROC_MAX);
}

void
proc_exec(struct privsep *ps, struct privsep_proc *procs, unsigned int nproc,
    int argc, char **argv)
{
        unsigned int             proc, nargc, i, proc_i;
        char                    **nargv;
        struct privsep_proc     *p;
        int                      fds[2];

        /* Prepare the new process argv. */
        nargv = calloc(argc + 5, sizeof(char *));
        if (nargv == NULL)
                fatal("%s: calloc", __func__);

        /* Copy call argument first. */
        nargc = 0;
        nargv[nargc++] = argv[0];

        /* Set process name argument and save the position. */
        nargv[nargc++] = "-P";
        proc_i = nargc;
        nargc++;

        /* Point process instance arg to stack and copy the original args. */
        for (i = 1; i < (unsigned int) argc; i++)
                nargv[nargc++] = argv[i];

        nargv[nargc] = NULL;

        for (proc = 0; proc < nproc; proc++) {
                p = &procs[proc];

                /* Update args with process title. */
                nargv[proc_i] = (char *)(uintptr_t)p->p_title;

                /* Create socket for communication back to the Parent. */
                if (socketpair(AF_UNIX, SOCK_STREAM|SOCK_NONBLOCK|SOCK_CLOEXEC,
                    PF_UNSPEC, fds) == -1)
                        fatal("socketpair");

                /* Fire up child process. */
                switch (fork()) {
                case -1:
                        fatal("%s: fork", __func__);
                        break;
                case 0:
                        close(fds[0]);
                        /* Prepare parent socket. */
                        if (fds[1] != PROC_PARENT_SOCK_FILENO) {
                                if (dup2(fds[1], PROC_PARENT_SOCK_FILENO) == -1)
                                        fatal("dup2");
                        } else if (fcntl(fds[1], F_SETFD, 0) == -1)
                                fatal("fcntl");

                        execvp(argv[0], nargv);
                        fatal("%s: execvp", __func__);
                        break;
                default:
                        ps->ps_pipes[p->p_id] = fds[0];
                        close(fds[1]);
                        break;
                }
        }
        free(nargv);
}

void
proc_connect(struct privsep *ps)
{
        struct imsgev           *iev;
        enum privsep_procid     dst;

        /* Don't distribute any sockets if we are not really going to run. */
        if (ps->ps_noaction)
                return;

        for (dst = 0; dst < PROC_MAX; dst++) {
                /* We don't communicate with ourselves. */
                if (dst == PROC_PARENT)
                        continue;

                iev = &ps->ps_ievs[dst];
                if (imsgbuf_init(&iev->ibuf, ps->ps_pipes[dst]) == -1)
                        fatal("imsgbuf_init");
                imsgbuf_allow_fdpass(&iev->ibuf);
                event_set(&iev->ev, iev->ibuf.fd, iev->events,
                    iev->handler, iev->data);
                event_add(&iev->ev, NULL);
        }
}

void
proc_init(struct privsep *ps, struct privsep_proc *procs, unsigned int nprocs,
    int debug, int argc, char **argv, enum privsep_procid proc_id)
{
        struct privsep_proc     *p = NULL;
        unsigned int             proc;

        /* Don't initiate anything if we are not really going to run. */
        if (ps->ps_noaction)
                return;

        privsep_process = proc_id;

        if (proc_id == PROC_PARENT) {
                proc_setup(ps, procs, nprocs);

                if (!debug && daemon(0, 0) == -1)
                        fatal("failed to daemonize");

                /* Engage! */
                proc_exec(ps, procs, nprocs, argc, argv);
                return;
        }

        /* Initialize a child */
        for (proc = 0; proc < nprocs; proc++) {
                if (procs[proc].p_id != proc_id)
                        continue;
                p = &procs[proc];
                break;
        }
        if (p == NULL || p->p_init == NULL)
                fatalx("%s: process %d missing process initialization",
                    __func__, proc_id);

        p->p_init(ps, p);

        fatalx("failed to initiate child process");
}

void
proc_accept(struct privsep *ps, int fd, enum privsep_procid dst)
{
        struct imsgev           *iev;

        if (ps->ps_ievs[dst].data == NULL) {
#if DEBUG > 1
                log_debug("%s: %s src %d to dst %d not connected",
                    __func__, ps->ps_title[privsep_process],
                    privsep_process, dst);
#endif
                close(fd);
                return;
        }

        if (ps->ps_pipes[dst] != -1) {
                log_warnx("%s: duplicated descriptor", __func__);
                close(fd);
                return;
        } else
                ps->ps_pipes[dst] = fd;

        iev = &ps->ps_ievs[dst];
        if (imsgbuf_init(&iev->ibuf, fd) == -1)
                fatal("imsgbuf_init");
        imsgbuf_allow_fdpass(&iev->ibuf);
        event_set(&iev->ev, iev->ibuf.fd, iev->events, iev->handler, iev->data);
        event_add(&iev->ev, NULL);
}

void
proc_setup(struct privsep *ps, struct privsep_proc *procs, unsigned int nproc)
{
        unsigned int             dst, id;

        /* Initialize parent title, ps_instances and procs. */
        ps->ps_title[PROC_PARENT] = "vmd";

        for (dst = 0; dst < nproc; dst++) {
                procs[dst].p_ps = ps;
                if (procs[dst].p_cb == NULL)
                        procs[dst].p_cb = proc_dispatch_null;

                id = procs[dst].p_id;
                ps->ps_title[id] = procs[dst].p_title;

                /* With this set up, we are ready to call imsgbuf_init(). */
                ps->ps_ievs[id].handler = proc_dispatch;
                ps->ps_ievs[id].events = EV_READ;
                ps->ps_ievs[id].proc = &procs[dst];

                /* Use the data field to indicate this imsgev is initialized. */
                ps->ps_ievs[id].data = &ps->ps_ievs[id];
        }

        /* Mark fds as unused */
        for (dst = 0; dst < PROC_MAX; dst++)
                ps->ps_pipes[dst] = -1;
}

void
proc_kill(struct privsep *ps)
{
        char            *cause;
        pid_t            pid;
        int              len, status;

        if (privsep_process != PROC_PARENT)
                return;

        proc_close(ps);

        do {
                pid = waitpid(WAIT_ANY, &status, 0);
                if (pid <= 0)
                        continue;

                if (WIFSIGNALED(status)) {
                        len = asprintf(&cause, "terminated; signal %d",
                            WTERMSIG(status));
                } else if (WIFEXITED(status)) {
                        if (WEXITSTATUS(status) != 0)
                                len = asprintf(&cause, "exited abnormally");
                        else
                                len = 0;
                } else
                        len = -1;

                if (len == 0) {
                        /* child exited OK, don't print a warning message */
                } else if (len != -1) {
                        log_warnx("lost child: pid %u %s", pid, cause);
                        free(cause);
                } else
                        log_warnx("lost child: pid %u", pid);
        } while (pid != -1 || (pid == -1 && errno == EINTR));
}

void
proc_close(struct privsep *ps)
{
        unsigned int             dst;

        if (ps == NULL)
                return;

        for (dst = 0; dst < PROC_MAX; dst++) {
                if (ps->ps_ievs[dst].data == NULL)
                        continue;

                if (ps->ps_pipes[dst] == -1)
                        continue;

                /* Cancel the fd, close and invalidate the fd */
                event_del(&(ps->ps_ievs[dst].ev));
                imsgbuf_clear(&(ps->ps_ievs[dst].ibuf));
                close(ps->ps_pipes[dst]);
                ps->ps_pipes[dst] = -1;

                /* Null the data field to indicate this imsgev is closed. */
                ps->ps_ievs[dst].data = NULL;
        }
}

void
proc_shutdown(struct privsep_proc *p)
{
        struct privsep  *ps = p->p_ps;

        if (p->p_shutdown != NULL)
                (*p->p_shutdown)();

        proc_close(ps);

        log_info("%s exiting, pid %d", p->p_title, getpid());

        exit(0);
}

void
proc_sig_handler(int sig, short event, void *arg)
{
        struct privsep_proc     *p = arg;

        switch (sig) {
        case SIGINT:
        case SIGTERM:
                proc_shutdown(p);
                break;
        case SIGCHLD:
        case SIGHUP:
        case SIGPIPE:
        case SIGUSR1:
                /* ignore */
                break;
        default:
                fatalx("%s: unexpected signal", __func__);
                /* NOTREACHED */
        }
}

void
proc_run(struct privsep *ps, struct privsep_proc *p,
    struct privsep_proc *procs, unsigned int nproc,
    void (*run)(struct privsep *, struct privsep_proc *, void *), void *arg)
{
        struct passwd           *pw;
        const char              *root;
        struct control_sock     *rcs;

        log_procinit("%s", p->p_title);

        if (p->p_id == PROC_CONTROL) {
                if (control_init(ps, &ps->ps_csock) == -1)
                        fatalx("%s: control_init", __func__);
                TAILQ_FOREACH(rcs, &ps->ps_rcsocks, cs_entry)
                        if (control_init(ps, rcs) == -1)
                                fatalx("%s: control_init", __func__);
        }

        /* Use non-standard user */
        if (p->p_pw != NULL)
                pw = p->p_pw;
        else
                pw = ps->ps_pw;

        /* Change root directory */
        if (p->p_chroot != NULL)
                root = p->p_chroot;
        else
                root = pw->pw_dir;

        if (chroot(root) == -1)
                fatal("%s: chroot", __func__);
        if (chdir("/") == -1)
                fatal("%s: chdir(\"/\")", __func__);

        privsep_process = p->p_id;
        setproctitle("%s", p->p_title);

        if (setgroups(1, &pw->pw_gid) ||
            setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
            setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid))
                fatal("%s: cannot drop privileges", __func__);

        event_init();

        signal_set(&ps->ps_evsigint, SIGINT, proc_sig_handler, p);
        signal_set(&ps->ps_evsigterm, SIGTERM, proc_sig_handler, p);
        signal_set(&ps->ps_evsigchld, SIGCHLD, proc_sig_handler, p);
        signal_set(&ps->ps_evsighup, SIGHUP, proc_sig_handler, p);
        signal_set(&ps->ps_evsigpipe, SIGPIPE, proc_sig_handler, p);
        signal_set(&ps->ps_evsigusr1, SIGUSR1, proc_sig_handler, p);

        signal_add(&ps->ps_evsigint, NULL);
        signal_add(&ps->ps_evsigterm, NULL);
        signal_add(&ps->ps_evsigchld, NULL);
        signal_add(&ps->ps_evsighup, NULL);
        signal_add(&ps->ps_evsigpipe, NULL);
        signal_add(&ps->ps_evsigusr1, NULL);

        proc_setup(ps, procs, nproc);
        proc_accept(ps, PROC_PARENT_SOCK_FILENO, PROC_PARENT);
        if (p->p_id == PROC_CONTROL) {
                if (control_listen(&ps->ps_csock) == -1)
                        fatalx("%s: control_listen", __func__);
                TAILQ_FOREACH(rcs, &ps->ps_rcsocks, cs_entry)
                        if (control_listen(rcs) == -1)
                                fatalx("%s: control_listen", __func__);
        }

        DPRINTF("%s: %s, pid %d", __func__, p->p_title, getpid());

        if (run != NULL)
                run(ps, p, arg);

        event_dispatch();

        proc_shutdown(p);
}

void
proc_dispatch(int fd, short event, void *arg)
{
        struct imsgev           *iev = arg;
        struct privsep_proc     *p = iev->proc;
        struct privsep          *ps = p->p_ps;
        struct imsgbuf          *ibuf;
        struct imsg              imsg;
        ssize_t                  n;
        int                      verbose;
        const char              *title;
        uint32_t                 peer_id, type;
        pid_t                    pid;

        title = ps->ps_title[privsep_process];
        ibuf = &iev->ibuf;

        if (event & EV_READ) {
                if ((n = imsgbuf_read(ibuf)) == -1)
                        fatal("%s: imsgbuf_read", __func__);
                if (n == 0) {
                        /* this pipe is dead, so remove the event handler */
                        event_del(&iev->ev);
                        event_loopexit(NULL);
                        return;
                }
        }

        if (event & EV_WRITE) {
                if (imsgbuf_write(ibuf) == -1) {
                        if (errno == EPIPE) {
                                /* this pipe is dead, remove the handler */
                                event_del(&iev->ev);
                                event_loopexit(NULL);
                                return;
                        }
                        fatal("%s: imsgbuf_write", __func__);
                }
        }

        for (;;) {
                if ((n = imsg_get(ibuf, &imsg)) == -1)
                        fatal("%s: imsg_get", __func__);
                if (n == 0)
                        break;

                /*
                 * Check the message with the program callback
                 */
                if ((p->p_cb)(fd, p, &imsg) == 0) {
                        /* Message was handled by the callback, continue */
                        imsg_free(&imsg);
                        continue;
                }

                /*
                 * Generic message handling
                 */
                type = imsg_get_type(&imsg);
                peer_id = imsg_get_id(&imsg);
                pid = imsg_get_pid(&imsg);

                switch (type) {
                case IMSG_CTL_VERBOSE:
                        verbose = imsg_int_read(&imsg);
                        log_setverbose(verbose);
                        break;
                default:
                        fatalx("%s: %s got invalid imsg %d peerid %d from %s "
                            "%d", __func__, title, type, peer_id, p->p_title,
                            pid);
                }
                imsg_free(&imsg);
        }
        imsg_event_add(iev);
}

int
proc_dispatch_null(int fd, struct privsep_proc *p, struct imsg *imsg)
{
        return (-1);
}

/*
 * imsg helper functions
 */
void
imsg_event_add(struct imsgev *iev)
{
        imsg_event_add2(iev, NULL);
}

void
imsg_event_add2(struct imsgev *iev, struct event_base *ev_base)
{
        if (iev->handler == NULL) {
                imsgbuf_flush(&iev->ibuf);
                return;
        }

        iev->events = EV_READ;
        if (imsgbuf_queuelen(&iev->ibuf) > 0)
                iev->events |= EV_WRITE;

        event_del(&iev->ev);
        event_set(&iev->ev, iev->ibuf.fd, iev->events, iev->handler, iev->data);
        if (ev_base != NULL)
                event_base_set(ev_base, &iev->ev);
        event_add(&iev->ev, NULL);
}

int
imsg_compose_event(struct imsgev *iev, uint32_t type, uint32_t peerid,
    pid_t pid, int fd, void *data, size_t datalen)
{
        return imsg_compose_event2(iev, type, peerid, pid, fd, data, datalen,
            NULL);
}

int
imsg_compose_event2(struct imsgev *iev, uint32_t type, uint32_t peerid,
    pid_t pid, int fd, void *data, uint16_t datalen, struct event_base *ev_base)
{
        int     ret;

        ret = imsg_compose(&iev->ibuf, type, peerid, pid, fd, data, datalen);
        if (ret == -1)
                return (ret);
        imsg_event_add2(iev, ev_base);
        return (ret);
}

int
imsg_composev_event(struct imsgev *iev, uint32_t type, uint32_t peerid,
    pid_t pid, int fd, const struct iovec *iov, int iovcnt)
{
        int     ret;

        ret = imsg_composev(&iev->ibuf, type, peerid, pid, fd, iov, iovcnt);
        if (ret == -1)
                return (ret);
        imsg_event_add(iev);
        return (ret);
}

void
imsg_forward_event(struct imsgev *iev, struct imsg *imsg)
{
        if (imsg_forward(&iev->ibuf, imsg) == -1)
                fatalx("%s: imsg_forward", __func__);
        imsg_event_add(iev);
}

int
proc_compose_imsg(struct privsep *ps, enum privsep_procid id,
    uint32_t type, uint32_t peerid, int fd, void *data, size_t datalen)
{
        pid_t pid = 1;

        if (ps->ps_ievs[id].data == NULL)
                log_debug("%s: imsgev not initialized", __func__);

        if (imsg_compose_event(&ps->ps_ievs[id], type, peerid, pid, fd, data,
            datalen) == -1)
                return (-1);

        return (0);
}

int
proc_compose(struct privsep *ps, enum privsep_procid id, uint32_t type,
    void *data, size_t datalen)
{
        return (proc_compose_imsg(ps, id, type, -1, -1, data, datalen));
}

int
proc_composev_imsg(struct privsep *ps, enum privsep_procid id, uint32_t type,
    uint32_t peerid, int fd, const struct iovec *iov, int iovcnt)
{
        pid_t pid = 1;
        if (imsg_composev_event(&ps->ps_ievs[id], type, peerid, pid, fd, iov,
            iovcnt) == -1)
                return (-1);

        return (0);
}

int
proc_composev(struct privsep *ps, enum privsep_procid id,
    uint32_t type, const struct iovec *iov, int iovcnt)
{
        return (proc_composev_imsg(ps, id, type, -1, -1, iov, iovcnt));
}

int
proc_forward_imsg(struct privsep *ps, struct imsg *imsg, enum privsep_procid id,
    uint32_t new_peerid)
{
        int              fd, ret;
        size_t           sz;
        uint32_t         peerid, type;
        void            *data = NULL;

        fd = imsg_get_fd(imsg);
        sz = imsg_get_len(imsg);
        type = imsg_get_type(imsg);

        if (new_peerid == (uint32_t)(-1))
                peerid = imsg_get_id(imsg);
        else
                peerid = new_peerid;

        if (sz > 0) {
                data = malloc(sz);
                if (data == NULL)
                        return (ENOMEM);
                if (imsg_get_data(imsg, data, sz))
                        fatal("%s: imsg_get_data", __func__);
        }

        ret = proc_compose_imsg(ps, id, type, peerid, fd, data, sz);
        if (sz > 0)
                free(data);
        return (ret);
}

/* This function should only be called with care as it breaks async I/O */
int
proc_flush_imsg(struct privsep *ps, enum privsep_procid id)
{
        int              ret = 0;

        ret = imsgbuf_flush(&ps->ps_ievs[id].ibuf);
        if (ret == 0)
                imsg_event_add(&ps->ps_ievs[id]);

        return (ret);
}

unsigned int
imsg_uint_read(struct imsg *imsg)
{
        unsigned int val;

        if (imsg_get_data(imsg, &val, sizeof(val)))
                fatal("%s", __func__);

        return (val);
}

int
imsg_int_read(struct imsg *imsg)
{
        int val;

        if (imsg_get_data(imsg, &val, sizeof(val)))
                fatal("%s", __func__);

        return (val);
}

char *
imsg_string_read(struct imsg *imsg, size_t max)
{
        size_t i, sz;
        char *s = NULL;

        sz = imsg_get_len(imsg);
        if (sz > max) {
                log_warnx("%s: string too large", __func__);
                return (NULL);
        }
        s = malloc(sz);
        if (imsg_get_data(imsg, s, sz))
                fatal("%s: imsg_get_data", __func__);

        /* Guarantee NUL-termination. */
        s[sz - 1] = '\0';

        /* Ensure all characters are printable. */
        for (i = 0; i < sz; i++) {
                if (s[i] == '\0')
                        break;
                if (!isprint(s[i])) {
                        log_warnx("%s: non-printable character", __func__);
                        free(s);
                        return (NULL);
                }
        }

        return (s);
}