diff options
Diffstat (limited to 'crypto/openssh/uidswap.c')
| -rw-r--r-- | crypto/openssh/uidswap.c | 98 |
1 files changed, 62 insertions, 36 deletions
diff --git a/crypto/openssh/uidswap.c b/crypto/openssh/uidswap.c index 8e7c479..39952e2 100644 --- a/crypto/openssh/uidswap.c +++ b/crypto/openssh/uidswap.c @@ -12,9 +12,9 @@ */ #include "includes.h" -RCSID("$OpenBSD: uidswap.c,v 1.9 2000/09/07 20:27:55 deraadt Exp $"); +RCSID("$OpenBSD: uidswap.c,v 1.16 2001/04/20 16:32:22 markus Exp $"); -#include "ssh.h" +#include "log.h" #include "uidswap.h" /* @@ -26,58 +26,80 @@ RCSID("$OpenBSD: uidswap.c,v 1.9 2000/09/07 20:27:55 deraadt Exp $"); * POSIX saved uids or not. */ -#ifdef _POSIX_SAVED_IDS /* 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 -#endif /* _POSIX_SAVED_IDS */ /* Saved effective uid. */ -static uid_t saved_euid = 0; +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 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. */ void -temporarily_use_uid(uid_t uid) +temporarily_use_uid(struct passwd *pw) { -#ifdef SAVED_IDS_WORK_WITH_SETEUID - /* Save the current euid. */ + /* 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; + 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. */ - if (seteuid(uid) == -1) - debug("seteuid %u: %.100s", (u_int) uid, strerror(errno)); -#else /* SAVED_IDS_WORK_WITH_SETUID */ - /* Propagate the privileged uid to all of our uids. */ - if (setuid(geteuid()) < 0) - debug("setuid %u: %.100s", (u_int) geteuid(), strerror(errno)); - - /* Set the effective uid to the given (unprivileged) uid. */ - if (seteuid(uid) == -1) - debug("seteuid %u: %.100s", (u_int) uid, strerror(errno)); -#endif /* SAVED_IDS_WORK_WITH_SETEUID */ + if (setgroups(user_groupslen, user_groups) < 0) + fatal("setgroups: %.100s", strerror(errno)); + pw->pw_gid = pw->pw_gid; + 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)); } /* - * Restores to the original uid. + * Restores to the original (privileged) uid. */ void -restore_uid() +restore_uid(void) { -#ifdef SAVED_IDS_WORK_WITH_SETEUID - /* Set the effective uid back to the saved uid. */ + debug("restore_uid"); + /* it's a no-op unless privileged */ + if (!privileged) + return; + if (!temporarily_use_uid_effective) + fatal("restore_uid: temporarily_use_uid not effective"); + /* Set the effective uid back to the saved privileged uid. */ if (seteuid(saved_euid) < 0) - debug("seteuid %u: %.100s", (u_int) saved_euid, 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()); -#endif /* SAVED_IDS_WORK_WITH_SETEUID */ + fatal("seteuid %u: %.100s", (u_int) saved_euid, strerror(errno)); + 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; } /* @@ -85,8 +107,12 @@ restore_uid() * called while temporarily_use_uid is effective. */ void -permanently_set_uid(uid_t uid) +permanently_set_uid(struct passwd *pw) { - if (setuid(uid) < 0) - debug("setuid %u: %.100s", (u_int) uid, strerror(errno)); + if (temporarily_use_uid_effective) + fatal("restore_uid: temporarily_use_uid effective"); + if (setgid(pw->pw_gid) < 0) + fatal("setgid %u: %.100s", (u_int) pw->pw_gid, strerror(errno)); + if (setuid(pw->pw_uid) < 0) + fatal("setuid %u: %.100s", (u_int) pw->pw_uid, strerror(errno)); } |
