diff options
Diffstat (limited to 'src/userprivs.c')
-rw-r--r-- | src/userprivs.c | 279 |
1 files changed, 279 insertions, 0 deletions
diff --git a/src/userprivs.c b/src/userprivs.c new file mode 100644 index 0000000..3abb001 --- /dev/null +++ b/src/userprivs.c @@ -0,0 +1,279 @@ +/* This file is part of Pies. + Copyright (C) 2007, 2008, 2009 Sergey Poznyakoff + + Pies 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 3, or (at your option) + any later version. + + Pies 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 Pies. If not, see <http://www.gnu.org/licenses/>. */ + +#ifdef HAVE_CONFIG_H +# include <config.h> +#endif +#include <stdlib.h> +#include <string.h> +#include <pwd.h> +#include <grp.h> +#include <unistd.h> +#include <sysexits.h> +#include <stdbool.h> +#include "pies.h" + +static bool +str_eq (const void *elt1, const void *elt2) +{ + return strcmp (elt1, elt2) == 0; +} + +void +str_dispose (const void *elt) +{ + free ((void*)elt); +} + +gl_list_t +get_user_groups (gl_list_t init_list, const char *user) +{ + int rc; + struct group *gr; + gl_list_t list; + + list = gl_list_create_empty(&gl_linked_list_implementation, + str_eq, + NULL, + str_dispose, + false); + + if (init_list) + { + const void *p; + gl_list_iterator_t itr = gl_list_iterator (init_list); + while (gl_list_iterator_next (&itr, &p, NULL)) + { + char *s = xstrdup (p); + if (!gl_list_add_last (list, s)) + free (s); + } + gl_list_iterator_free (&itr); + } + + setgrent (); + for (rc = 0; rc == 0 && (gr = getgrent ());) + { + char **p; + for (p = gr->gr_mem; *p; p++) + if (strcmp (*p, user) == 0) + { + char *s = xstrdup (gr->gr_name); + if (!gl_list_add_last (list, s)) + free (s); + break; + } + } + endgrent (); + return list; +} + +/* Switch to the given UID/GID */ +int +switch_to_privs (uid_t uid, gid_t gid, gl_list_t retain_groups) +{ + int rc = 0; + gid_t *emptygidset; + size_t size = 1, j = 1; + + if (uid == 0) + { + logmsg (LOG_ERR, _("Refusing to run as root")); + return 1; + } + + /* Create a list of supplementary groups */ + size = 1 + (retain_groups ? gl_list_size (retain_groups) : 0); + emptygidset = xcalloc (size, sizeof emptygidset[0]); + emptygidset[0] = gid ? gid : getegid (); + + if (retain_groups) + { + const void *p; + gl_list_iterator_t itr = gl_list_iterator (retain_groups); + while (gl_list_iterator_next (&itr, &p, NULL)) + { + struct group *group = getgrnam ((const char*)p); + if (!group) + { + logmsg (LOG_ERR, _("unknown group: %s"), (const char*)p); + free (emptygidset); + return 1; + } + emptygidset[j++] = group->gr_gid; + } + gl_list_iterator_free (&itr); + } + + /* Reset group permissions */ + if (geteuid () == 0 && setgroups (j, emptygidset)) + { + logmsg (LOG_ERR, _("setgroups(1, %lu) failed: %s"), + (unsigned long) emptygidset[0], strerror (errno)); + rc = 1; + } + free (emptygidset); + + /* Switch to the user's gid. On some OSes the effective gid must + be reset first */ + +#if defined(HAVE_SETEGID) + if ((rc = setegid (gid)) < 0) + logmsg (LOG_ERR, _("setegid(%lu) failed: %s"), + (unsigned long) gid, strerror (errno)); +#elif defined(HAVE_SETREGID) + if ((rc = setregid (gid, gid)) < 0) + logmsg (LOG_ERR, _("setregid(%lu,%lu) failed: %s"), + (unsigned long) gid, (unsigned long) gid, strerror (errno)); +#elif defined(HAVE_SETRESGID) + if ((rc = setresgid (gid, gid, gid)) < 0) + logmsg (LOG_ERR, _("setresgid(%lu,%lu,%lu) failed: %s"), + (unsigned long) gid, + (unsigned long) gid, (unsigned long) gid, strerror (errno)); +#endif + + if (rc == 0 && gid != 0) + { + if ((rc = setgid (gid)) < 0 && getegid () != gid) + logmsg (LOG_ERR, _("setgid(%lu) failed: %s"), + (unsigned long) gid, strerror (errno)); + if (rc == 0 && getegid () != gid) + { + logmsg (LOG_ERR, _("Cannot set effective gid to %lu"), + (unsigned long) gid); + rc = 1; + } + } + + /* Now reset uid */ + if (rc == 0 && uid != 0) + { + uid_t euid; + + if (setuid (uid) + || geteuid () != uid + || (getuid () != uid && (geteuid () == 0 || getuid () == 0))) + { + +#if defined(HAVE_SETREUID) + if (geteuid () != uid) + { + if (setreuid (uid, -1) < 0) + { + logmsg (LOG_ERR, _("setreuid(%lu,-1) failed: %s"), + (unsigned long) uid, strerror (errno)); + rc = 1; + } + if (setuid (uid) < 0) + { + logmsg (LOG_ERR, _("second setuid(%lu) failed: %s"), + (unsigned long) uid, strerror (errno)); + rc = 1; + } + } + else +#endif + { + logmsg (LOG_ERR, _("setuid(%lu) failed: %s"), + (unsigned long) uid, strerror (errno)); + rc = 1; + } + } + + euid = geteuid (); + if (uid != 0 && setuid (0) == 0) + { + logmsg (LOG_ERR, _("seteuid(0) succeeded when it should not")); + rc = 1; + } + else if (uid != euid && setuid (euid) == 0) + { + logmsg (LOG_ERR, _("Cannot drop non-root setuid privileges")); + rc = 1; + } + + } + + return rc; +} + + +void +pies_priv_setup (struct pies_privs *privs) +{ + struct passwd *pw; + gl_list_t grplist = 0; + + if (!privs || !privs->user) + return; + + pw = getpwnam (privs->user); + if (!pw) + { + logmsg (LOG_ERR, _("no such user: %s"), privs->user); + exit (EX_CONFIG); + } + + if (privs->allgroups) + grplist = get_user_groups (privs->groups, privs->user); + if (switch_to_privs (pw->pw_uid, pw->pw_gid, + grplist ? grplist : privs->groups)) + exit (EX_SOFTWARE); + if (grplist) + gl_list_free (grplist); +} + + +void +pies_epriv_setup (struct pies_privs *privs) +{ + uid_t uid; + gid_t gid; + + if (privs) + { + struct passwd *pw; + if (!privs->user) + return; + + pw = getpwnam (privs->user); + if (!pw) + { + logmsg (LOG_ERR, _("No such user: %s"), privs->user); + exit (EX_CONFIG); + } + uid = pw->pw_uid; + gid = pw->pw_gid; + } + else + { + uid = 0; + gid = 0; + } + + if (setegid (gid)) + { + logmsg (LOG_ERR, _("Cannot switch to EGID %lu: %s"), + (unsigned long) gid, strerror (errno)); + exit (EX_USAGE); + } + if (seteuid (uid)) + { + logmsg (LOG_ERR, _("Cannot switch to EUID %lu: %s"), + (unsigned long) uid, strerror (errno)); + exit (EX_USAGE); + } +} |