X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/a3626e1226c8eecce855a2bc4a500d6939cbdf4c..ccd01778c21e2fc83d9b0da282862828d4832757:/uidswap.c diff --git a/uidswap.c b/uidswap.c index e2979014..83764839 100644 --- a/uidswap.c +++ b/uidswap.c @@ -1,3 +1,4 @@ +/* $OpenBSD: uidswap.c,v 1.35 2006/08/03 03:34:42 deraadt Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland @@ -12,10 +13,19 @@ */ #include "includes.h" -RCSID("$OpenBSD: uidswap.c,v 1.16 2001/04/20 16:32:22 markus Exp $"); + +#include +#include +#include +#include +#include +#include + +#include #include "log.h" #include "uidswap.h" +#include "xmalloc.h" /* * Note: all these functions must work in all of the following cases: @@ -26,17 +36,21 @@ RCSID("$OpenBSD: uidswap.c,v 1.16 2001/04/20 16:32:22 markus Exp $"); * POSIX saved uids or not. */ +#if defined(_POSIX_SAVED_IDS) && !defined(BROKEN_SAVED_UIDS) /* Lets assume that posix saved ids also work with seteuid, even though that is not part of the posix specification. */ - +#define SAVED_IDS_WORK_WITH_SETEUID +/* Saved effective uid. */ +static uid_t saved_euid = 0; +static gid_t saved_egid = 0; +#endif + /* Saved effective uid. */ static int privileged = 0; static int temporarily_use_uid_effective = 0; -static uid_t saved_euid = 0; -static gid_t saved_egid; -static gid_t saved_egroups[NGROUPS_MAX], user_groups[NGROUPS_MAX]; +static gid_t *saved_egroups = NULL, *user_groups = NULL; static int saved_egroupslen = -1, user_groupslen = -1; - + /* * Temporarily changes to the given uid. If the effective user * id is not root, this does nothing. This call cannot be nested. @@ -44,61 +58,148 @@ static int saved_egroupslen = -1, user_groupslen = -1; void temporarily_use_uid(struct passwd *pw) { - /* Save the current euid, and egroups. */ - saved_euid = geteuid(); - debug("temporarily_use_uid: %d/%d (e=%d)", - pw->pw_uid, pw->pw_gid, saved_euid); - if (saved_euid != 0) { - privileged = 0; - return; - } - privileged = 1; - temporarily_use_uid_effective = 1; + /* Save the current euid, and egroups. */ +#ifdef SAVED_IDS_WORK_WITH_SETEUID + saved_euid = geteuid(); saved_egid = getegid(); - saved_egroupslen = getgroups(NGROUPS_MAX, saved_egroups); - if (saved_egroupslen < 0) - fatal("getgroups: %.100s", strerror(errno)); - - /* set and save the user's groups */ - if (user_groupslen == -1) { - if (initgroups(pw->pw_name, pw->pw_gid) < 0) - fatal("initgroups: %s: %.100s", pw->pw_name, - strerror(errno)); - user_groupslen = getgroups(NGROUPS_MAX, user_groups); - if (user_groupslen < 0) - fatal("getgroups: %.100s", strerror(errno)); - } - /* Set the effective uid to the given (unprivileged) uid. */ + debug("temporarily_use_uid: %u/%u (e=%u/%u)", + (u_int)pw->pw_uid, (u_int)pw->pw_gid, + (u_int)saved_euid, (u_int)saved_egid); +#ifndef HAVE_CYGWIN + if (saved_euid != 0) { + privileged = 0; + return; + } +#endif +#else + if (geteuid() != 0) { + privileged = 0; + return; + } +#endif /* SAVED_IDS_WORK_WITH_SETEUID */ + + privileged = 1; + temporarily_use_uid_effective = 1; + + saved_egroupslen = getgroups(0, NULL); + if (saved_egroupslen < 0) + fatal("getgroups: %.100s", strerror(errno)); + if (saved_egroupslen > 0) { + saved_egroups = xrealloc(saved_egroups, + saved_egroupslen, sizeof(gid_t)); + if (getgroups(saved_egroupslen, saved_egroups) < 0) + fatal("getgroups: %.100s", strerror(errno)); + } else { /* saved_egroupslen == 0 */ + if (saved_egroups != NULL) + xfree(saved_egroups); + } + + /* set and save the user's groups */ + if (user_groupslen == -1) { + if (initgroups(pw->pw_name, pw->pw_gid) < 0) + fatal("initgroups: %s: %.100s", pw->pw_name, + strerror(errno)); + + user_groupslen = getgroups(0, NULL); + if (user_groupslen < 0) + fatal("getgroups: %.100s", strerror(errno)); + if (user_groupslen > 0) { + user_groups = xrealloc(user_groups, + user_groupslen, sizeof(gid_t)); + if (getgroups(user_groupslen, user_groups) < 0) + fatal("getgroups: %.100s", strerror(errno)); + } else { /* user_groupslen == 0 */ + if (user_groups) + xfree(user_groups); + } + } + /* Set the effective uid to the given (unprivileged) uid. */ if (setgroups(user_groupslen, user_groups) < 0) fatal("setgroups: %.100s", strerror(errno)); - pw->pw_gid = pw->pw_gid; +#ifndef SAVED_IDS_WORK_WITH_SETEUID + /* Propagate the privileged gid to all of our gids. */ + if (setgid(getegid()) < 0) + debug("setgid %u: %.100s", (u_int) getegid(), strerror(errno)); + /* Propagate the privileged uid to all of our uids. */ + if (setuid(geteuid()) < 0) + debug("setuid %u: %.100s", (u_int) geteuid(), strerror(errno)); +#endif /* SAVED_IDS_WORK_WITH_SETEUID */ if (setegid(pw->pw_gid) < 0) - fatal("setegid %u: %.100s", (u_int) pw->pw_gid, - strerror(errno)); - if (seteuid(pw->pw_uid) == -1) - fatal("seteuid %u: %.100s", (u_int) pw->pw_uid, - strerror(errno)); + fatal("setegid %u: %.100s", (u_int)pw->pw_gid, + strerror(errno)); + if (seteuid(pw->pw_uid) == -1) + fatal("seteuid %u: %.100s", (u_int)pw->pw_uid, + strerror(errno)); +} + +void +permanently_drop_suid(uid_t uid) +{ + uid_t old_uid = getuid(); + + debug("permanently_drop_suid: %u", (u_int)uid); +#if defined(HAVE_SETRESUID) && !defined(BROKEN_SETRESUID) + if (setresuid(uid, uid, uid) < 0) + fatal("setresuid %u: %.100s", (u_int)uid, strerror(errno)); +#elif defined(HAVE_SETREUID) && !defined(BROKEN_SETREUID) + if (setreuid(uid, uid) < 0) + fatal("setreuid %u: %.100s", (u_int)uid, strerror(errno)); +#else +# ifndef SETEUID_BREAKS_SETUID + if (seteuid(uid) < 0) + fatal("seteuid %u: %.100s", (u_int)uid, strerror(errno)); +# endif + if (setuid(uid) < 0) + fatal("setuid %u: %.100s", (u_int)uid, strerror(errno)); +#endif + +#ifndef HAVE_CYGWIN + /* Try restoration of UID if changed (test clearing of saved uid) */ + if (old_uid != uid && + (setuid(old_uid) != -1 || seteuid(old_uid) != -1)) + fatal("%s: was able to restore old [e]uid", __func__); +#endif + + /* Verify UID drop was successful */ + if (getuid() != uid || geteuid() != uid) { + fatal("%s: euid incorrect uid:%u euid:%u (should be %u)", + __func__, (u_int)getuid(), (u_int)geteuid(), (u_int)uid); + } } - + /* * Restores to the original (privileged) uid. */ void restore_uid(void) { - debug("restore_uid"); /* it's a no-op unless privileged */ - if (!privileged) + if (!privileged) { + debug("restore_uid: (unprivileged)"); return; + } if (!temporarily_use_uid_effective) fatal("restore_uid: temporarily_use_uid not effective"); + +#ifdef SAVED_IDS_WORK_WITH_SETEUID + debug("restore_uid: %u/%u", (u_int)saved_euid, (u_int)saved_egid); /* Set the effective uid back to the saved privileged uid. */ if (seteuid(saved_euid) < 0) - fatal("seteuid %u: %.100s", (u_int) saved_euid, strerror(errno)); + fatal("seteuid %u: %.100s", (u_int)saved_euid, strerror(errno)); + if (setegid(saved_egid) < 0) + fatal("setegid %u: %.100s", (u_int)saved_egid, strerror(errno)); +#else /* SAVED_IDS_WORK_WITH_SETEUID */ + /* + * We are unable to restore the real uid to its unprivileged value. + * Propagate the real uid (usually more privileged) to effective uid + * as well. + */ + setuid(getuid()); + setgid(getgid()); +#endif /* SAVED_IDS_WORK_WITH_SETEUID */ + if (setgroups(saved_egroupslen, saved_egroups) < 0) fatal("setgroups: %.100s", strerror(errno)); - if (setegid(saved_egid) < 0) - fatal("setegid %u: %.100s", (u_int) saved_egid, strerror(errno)); temporarily_use_uid_effective = 0; } @@ -109,10 +210,79 @@ restore_uid(void) void permanently_set_uid(struct passwd *pw) { + uid_t old_uid = getuid(); + gid_t old_gid = getgid(); + + if (pw == NULL) + fatal("permanently_set_uid: no user given"); if (temporarily_use_uid_effective) - fatal("restore_uid: temporarily_use_uid effective"); + fatal("permanently_set_uid: temporarily_use_uid effective"); + debug("permanently_set_uid: %u/%u", (u_int)pw->pw_uid, + (u_int)pw->pw_gid); + +#if defined(HAVE_SETRESGID) && !defined(BROKEN_SETRESGID) + if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) < 0) + fatal("setresgid %u: %.100s", (u_int)pw->pw_gid, strerror(errno)); +#elif defined(HAVE_SETREGID) && !defined(BROKEN_SETREGID) + if (setregid(pw->pw_gid, pw->pw_gid) < 0) + fatal("setregid %u: %.100s", (u_int)pw->pw_gid, strerror(errno)); +#else + if (setegid(pw->pw_gid) < 0) + fatal("setegid %u: %.100s", (u_int)pw->pw_gid, strerror(errno)); if (setgid(pw->pw_gid) < 0) - fatal("setgid %u: %.100s", (u_int) pw->pw_gid, strerror(errno)); + fatal("setgid %u: %.100s", (u_int)pw->pw_gid, strerror(errno)); +#endif + +#ifdef __APPLE__ + /* + * OS X requires initgroups after setgid to opt back into + * memberd support for >16 supplemental groups. + */ + if (initgroups(pw->pw_name, pw->pw_gid) < 0) + fatal("initgroups %.100s %u: %.100s", + pw->pw_name, (u_int)pw->pw_gid, strerror(errno)); +#endif + +#if defined(HAVE_SETRESUID) && !defined(BROKEN_SETRESUID) + if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) < 0) + fatal("setresuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno)); +#elif defined(HAVE_SETREUID) && !defined(BROKEN_SETREUID) + if (setreuid(pw->pw_uid, pw->pw_uid) < 0) + fatal("setreuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno)); +#else +# ifndef SETEUID_BREAKS_SETUID + if (seteuid(pw->pw_uid) < 0) + fatal("seteuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno)); +# endif if (setuid(pw->pw_uid) < 0) - fatal("setuid %u: %.100s", (u_int) pw->pw_uid, strerror(errno)); + fatal("setuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno)); +#endif + +#ifndef HAVE_CYGWIN + /* Try restoration of GID if changed (test clearing of saved gid) */ + if (old_gid != pw->pw_gid && pw->pw_uid != 0 && + (setgid(old_gid) != -1 || setegid(old_gid) != -1)) + fatal("%s: was able to restore old [e]gid", __func__); +#endif + + /* Verify GID drop was successful */ + if (getgid() != pw->pw_gid || getegid() != pw->pw_gid) { + fatal("%s: egid incorrect gid:%u egid:%u (should be %u)", + __func__, (u_int)getgid(), (u_int)getegid(), + (u_int)pw->pw_gid); + } + +#ifndef HAVE_CYGWIN + /* Try restoration of UID if changed (test clearing of saved uid) */ + if (old_uid != pw->pw_uid && + (setuid(old_uid) != -1 || seteuid(old_uid) != -1)) + fatal("%s: was able to restore old [e]uid", __func__); +#endif + + /* Verify UID drop was successful */ + if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) { + fatal("%s: euid incorrect uid:%u euid:%u (should be %u)", + __func__, (u_int)getuid(), (u_int)geteuid(), + (u_int)pw->pw_uid); + } }