/*

 * libwebsockets - small server side websockets and web server implementation

 *

 * Copyright (C) 2010 - 2019 Andy Green <andy@warmcat.com>

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to

 * deal in the Software without restriction, including without limitation the

 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or

 * sell copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS

 * IN THE SOFTWARE.

 */

#if !defined(_GNU_SOURCE)

#define _GNU_SOURCE

#endif

#include "private-lib-core.h"

#include <pwd.h>

#include <grp.h>

#if defined(LWS_HAVE_SYS_CAPABILITY_H) && defined(LWS_HAVE_LIBCAP)

static void

_lws_plat_apply_caps(unsigned int mode, const cap_value_t *cv, int count)

{

  cap_t caps;

  if (!count)

    return;

  caps = cap_get_proc();

  cap_set_flag(caps, (cap_flag_t)mode, count, cv, CAP_SET);

  cap_set_proc(caps);

  prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0);

  cap_free(caps);

}

#endif

int

lws_plat_user_colon_group_to_ids(const char *u_colon_g, uid_t *puid, gid_t *pgid)

{

  const char *colon = strchr(u_colon_g, ':');

  char u[33];

  struct group *g;

  struct passwd *p;

  size_t ulen;

  if (!colon)

    return 1;

  ulen = (size_t)(unsigned int)lws_ptr_diff(colon, u_colon_g);

  if (ulen < 2 || ulen > sizeof(u) - 1)

    return 1;

  memcpy(u, u_colon_g, ulen);

  u[ulen] = '\0';

  colon++;

#if defined(LWS_HAVE_GETGRNAM_R)

  {

    struct group gr;

    char strs[1024];

    if (getgrnam_r(colon, &gr, strs, sizeof(strs), &g) || !g) {

#else

  {

    g = getgrnam(colon);

    if (!g) {

#endif

      lwsl_err("%s: unknown group '%s'\n", __func__, colon);

      return 1;

    }

    *pgid = g->gr_gid;

  }

#if defined(LWS_HAVE_GETPWNAM_R)

  {

    struct passwd pr;

    char strs[1024];

    if (getpwnam_r(u, &pr, strs, sizeof(strs), &p) || !p) {

#else

  {

    p = getpwnam(u);

    if (!p) {

#endif

      lwsl_err("%s: unknown user '%s'\n", __func__, u);

      return 1;

    }

    *puid = p->pw_uid;

  }

  return 0;

}

int

lws_plat_drop_app_privileges(struct lws_context *context, int actually_drop)

{

  struct passwd *p;

  struct group *g;

  /* if he gave us the groupname, align gid to match it */

  if (context->groupname) {

#if defined(LWS_HAVE_GETGRNAM_R)

    struct group gr;

    char strs[1024];

    if (!getgrnam_r(context->groupname, &gr, strs, sizeof(strs), &g) && g) {

#else

    g = getgrnam(context->groupname);

    if (g) {

#endif

      lwsl_cx_info(context, "group %s -> gid %u",

          context->groupname, g->gr_gid);

      context->gid = g->gr_gid;

    } else {

      lwsl_cx_err(context, "unknown groupname '%s'",

         context->groupname);

      return 1;

    }

  }

  /* if he gave us the username, align uid to match it */

  if (context->username) {

#if defined(LWS_HAVE_GETPWNAM_R)

    struct passwd pr;

    char strs[1024];

    if (!getpwnam_r(context->username, &pr, strs, sizeof(strs), &p) && p) {

#else

    p = getpwnam(context->username);

    if (p) {

#endif

      context->uid = p->pw_uid;

      lwsl_cx_info(context, "username %s -> uid %u",

          context->username, (unsigned int)p->pw_uid);

    } else {

      lwsl_cx_err(context, "unknown username %s",

         context->username);

      return 1;

    }

  }

  if (!actually_drop)

    return 0;

  /* if he gave us the gid or we have it from the groupname, set it */

  if (context->gid && context->gid != (gid_t)-1l) {

#if defined(LWS_HAVE_GETGRGID_R)

    struct group gr;

    char strs[1024];

    if (getgrgid_r(context->gid, &gr, strs, sizeof(strs), &g) || !g) {

#else

    g = getgrgid(context->gid);

    if (!g) {

#endif

      lwsl_cx_err(context, "cannot find name for gid %d",

          context->gid);

      return 1;

    }

    if (setgid(context->gid)) {

      lwsl_cx_err(context, "setgid: %s failed",

            strerror(LWS_ERRNO));

      return 1;

    }

    lwsl_cx_notice(context, "effective group '%s'", g->gr_name);

  } else

    lwsl_cx_info(context, "not changing group");

  /* if he gave us the uid or we have it from the username, set it */

  if (context->uid && context->uid != (uid_t)-1l) {

#if defined(LWS_HAVE_GETPWUID_R)

    struct passwd pr;

    char strs[1024];

    if (getpwuid_r(context->uid, &pr, strs, sizeof(strs), &p) || !p) {

#else

    p = getpwuid(context->uid);

    if (!p) {

#endif

      lwsl_cx_err(context, "getpwuid: unable to find uid %d",

         context->uid);

      return 1;

    }

#if defined(LWS_HAVE_SYS_CAPABILITY_H) && defined(LWS_HAVE_LIBCAP)

    _lws_plat_apply_caps(CAP_PERMITTED, context->caps,

             context->count_caps);

#endif

    if (initgroups(p->pw_name,

#if defined(__APPLE__)

        (int)

#endif

        context->gid))

      return 1;

    if (setuid(context->uid)) {

      lwsl_cx_err(context, "setuid: %s failed",

            strerror(LWS_ERRNO));

      return 1;

    } else

      lwsl_cx_notice(context, "effective user '%s'",

          p->pw_name);

#if defined(LWS_HAVE_SYS_CAPABILITY_H) && defined(LWS_HAVE_LIBCAP)

    _lws_plat_apply_caps(CAP_EFFECTIVE, context->caps,

             context->count_caps);

    if (context->count_caps) {

      int n;

      for (n = 0; n < context->count_caps; n++)

        lwsl_cx_notice(context, "   RETAINING CAP %d",

              (int)context->caps[n]);

    }

#endif

  } else

    lwsl_cx_info(context, "not changing user");

  return 0;

}