/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) NGINX, Inc.
 */

#include <nxt_main.h>
#include <sys/types.h>
#include <nxt_conf.h>
#include <nxt_clone.h>

#if (NXT_HAVE_CLONE)

pid_t
nxt_clone(nxt_int_t flags)
{
#if defined(__s390x__) || defined(__s390__) || defined(__CRIS__)
    return syscall(__NR_clone, NULL, flags);
#else
    return syscall(__NR_clone, flags, NULL);
#endif
}

#endif


#if (NXT_HAVE_CLONE_NEWUSER)

/* map uid 65534 to unit pid */
#define NXT_DEFAULT_UNPRIV_MAP "65534 %d 1"

nxt_int_t nxt_clone_proc_setgroups(nxt_task_t *task, pid_t child_pid,
    const char *str);
nxt_int_t nxt_clone_proc_map_set(nxt_task_t *task, const char* mapfile,
    pid_t pid, nxt_int_t defval, nxt_conf_value_t *mapobj);
nxt_int_t nxt_clone_proc_map_write(nxt_task_t *task, const char *mapfile,
    pid_t pid, u_char *mapinfo);


typedef struct {
    nxt_int_t container;
    nxt_int_t host;
    nxt_int_t size;
} nxt_clone_procmap_t;


nxt_int_t
nxt_clone_proc_setgroups(nxt_task_t *task, pid_t child_pid, const char *str)
{
    int     fd, n;
    u_char  *p, *end;
    u_char  path[PATH_MAX];

    end = path + PATH_MAX;
    p = nxt_sprintf(path, end, "/proc/%d/setgroups", child_pid);
    *p = '\0';

    if (nxt_slow_path(p == end)) {
        nxt_alert(task, "error write past the buffer: %s", path);
        return NXT_ERROR;
    }

    fd = open((char *)path, O_RDWR);

    if (fd == -1) {
        /*
         * If the /proc/pid/setgroups doesn't exists, we are
         * safe to set uid/gid maps. But if the error is anything
         * other than ENOENT, then we should abort and let user know.
         */

        if (errno != ENOENT) {
            nxt_alert(task, "open(%s): %E", path, nxt_errno);
            return NXT_ERROR;
        }

        return NXT_OK;
    }

    n = write(fd, str, strlen(str));
    close(fd);

    if (nxt_slow_path(n == -1)) {
        nxt_alert(task, "write(%s): %E", path, nxt_errno);
        return NXT_ERROR;
    }

    return NXT_OK;
}


nxt_int_t
nxt_clone_proc_map_write(nxt_task_t *task, const char *mapfile, pid_t pid,
    u_char *mapinfo)
{
    int      len, mapfd;
    u_char   *p, *end;
    ssize_t  n;
    u_char   buf[256];

    end = buf + sizeof(buf);

    p = nxt_sprintf(buf, end, "/proc/%d/%s", pid, mapfile);
    if (nxt_slow_path(p == end)) {
        nxt_alert(task, "writing past the buffer");
        return NXT_ERROR;
    }

    *p = '\0';

    mapfd = open((char*)buf, O_RDWR);
    if (nxt_slow_path(mapfd == -1)) {
        nxt_alert(task, "failed to open proc map (%s) %E", buf, nxt_errno);
        return NXT_ERROR;
    }

    len = nxt_strlen(mapinfo);

    n = write(mapfd, (char *)mapinfo, len);
    if (nxt_slow_path(n != len)) {

        if (n == -1 && nxt_errno == EINVAL) {
            nxt_alert(task, "failed to write %s: Check kernel maximum " \
                      "allowed lines %E", buf, nxt_errno);

        } else {
            nxt_alert(task, "failed to write proc map (%s) %E", buf,
                      nxt_errno);
        }

        close(mapfd);

        return NXT_ERROR;
    }

    close(mapfd);

    return NXT_OK;
}


nxt_int_t
nxt_clone_proc_map_set(nxt_task_t *task, const char* mapfile, pid_t pid,
    nxt_int_t defval, nxt_conf_value_t *mapobj)
{
    u_char            *p, *end, *mapinfo;
    nxt_int_t         container, host, size;
    nxt_int_t         ret, len, count, i;
    nxt_conf_value_t  *obj, *value;

    static nxt_str_t str_cont = nxt_string("container");
    static nxt_str_t str_host = nxt_string("host");
    static nxt_str_t str_size = nxt_string("size");

    /*
     * uid_map one-entry size:
     *   alloc space for 3 numbers (32bit) plus 2 spaces and \n.
     */
    len = sizeof(u_char) * (10 + 10 + 10 + 2 + 1);

    if (mapobj != NULL) {
        count = nxt_conf_array_elements_count(mapobj);

        if (count == 0) {
            goto default_map;
        }

        len = len * count + 1;

        mapinfo = nxt_malloc(len);
        if (nxt_slow_path(mapinfo == NULL)) {
            nxt_alert(task, "failed to allocate uid_map buffer");
            return NXT_ERROR;
        }

        p = mapinfo;
        end = mapinfo + len;

        for (i = 0; i < count; i++) {
            obj = nxt_conf_get_array_element(mapobj, i);

            value = nxt_conf_get_object_member(obj, &str_cont, NULL);
            container = nxt_conf_get_integer(value);

            value = nxt_conf_get_object_member(obj, &str_host, NULL);
            host = nxt_conf_get_integer(value);

            value = nxt_conf_get_object_member(obj, &str_size, NULL);
            size = nxt_conf_get_integer(value);

            p = nxt_sprintf(p, end, "%d %d %d", container, host, size);
            if (nxt_slow_path(p == end)) {
                nxt_alert(task, "write past the uid_map buffer");
                nxt_free(mapinfo);
                return NXT_ERROR;
            }

            if (i+1 < count) {
                *p++ = '\n';

            } else {
                *p = '\0';
            }
        }

    } else {

default_map:

        mapinfo = nxt_malloc(len);
        if (nxt_slow_path(mapinfo == NULL)) {
            nxt_alert(task, "failed to allocate uid_map buffer");
            return NXT_ERROR;
        }

        end = mapinfo + len;
        p = nxt_sprintf(mapinfo, end, NXT_DEFAULT_UNPRIV_MAP, defval);
        *p = '\0';

        if (nxt_slow_path(p == end)) {
            nxt_alert(task, "write past the %s buffer", mapfile);
            nxt_free(mapinfo);
            return NXT_ERROR;
        }
    }

    ret = nxt_clone_proc_map_write(task, mapfile, pid, mapinfo);

    nxt_free(mapinfo);

    return ret;
}


nxt_int_t
nxt_clone_proc_map(nxt_task_t *task, pid_t pid, nxt_process_clone_t *clone)
{
    nxt_int_t      ret;
    nxt_int_t      uid, gid;
    const char     *rule;
    nxt_runtime_t  *rt;

    rt  = task->thread->runtime;
    uid = geteuid();
    gid = getegid();

    rule = rt->capabilities.setid ? "allow" : "deny";

    ret = nxt_clone_proc_map_set(task, "uid_map", pid, uid, clone->uidmap);
    if (nxt_slow_path(ret != NXT_OK)) {
        return NXT_ERROR;
    }

    ret = nxt_clone_proc_setgroups(task, pid, rule);
    if (nxt_slow_path(ret != NXT_OK)) {
        nxt_alert(task, "failed to write /proc/%d/setgroups", pid);
        return NXT_ERROR;
    }

    ret = nxt_clone_proc_map_set(task, "gid_map", pid, gid, clone->gidmap);
    if (nxt_slow_path(ret != NXT_OK)) {
        return NXT_ERROR;
    }

    return NXT_OK;
}

#endif