X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/63bd8c365b56b25157969008ff5b69fb04aa4664..5486a45797557bd2ffca421ca5e7ad2441f4db59:/uidswap.c

diff --git a/uidswap.c b/uidswap.c
index 7cfacd4a..4cabaa44 100644
--- a/uidswap.c
+++ b/uidswap.c
@@ -12,7 +12,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: uidswap.c,v 1.14 2001/04/06 21:00:16 markus Exp $");
+RCSID("$OpenBSD: uidswap.c,v 1.24 2003/05/29 16:58:45 deraadt Exp $");
 
 #include "log.h"
 #include "uidswap.h"
@@ -26,17 +26,21 @@ RCSID("$OpenBSD: uidswap.c,v 1.14 2001/04/06 21:00:16 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 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 +48,91 @@ 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;
-        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 (setgroups(user_groupslen, user_groups) < 0)
+	/* Save the current euid, and egroups. */
+#ifdef SAVED_IDS_WORK_WITH_SETEUID
+	saved_euid = geteuid();
+	saved_egid = getegid();
+	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);
+	if (saved_euid != 0) {
+		privileged = 0;
+		return;
+	}
+#else
+	if (geteuid() != 0) {
+		privileged = 0;
+		return;
+	}
+#endif /* SAVED_IDS_WORK_WITH_SETEUID */
+
+	privileged = 1;
+	temporarily_use_uid_effective = 1;
+	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 (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));
+#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));
 }
-  
+
 /*
- * Restores to the original 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");
-	/* Set the effective uid back to the saved uid. */
+
+#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));
-        if (setgroups(saved_egroupslen, saved_egroups) < 0)
+		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 +143,65 @@ restore_uid(void)
 void
 permanently_set_uid(struct passwd *pw)
 {
+	uid_t old_uid = getuid();
+	gid_t old_gid = getgid();
+
 	if (temporarily_use_uid_effective)
-		fatal("restore_uid: temporarily_use_uid effective");
-	if (setuid(pw->pw_uid) < 0)
-		fatal("setuid %u: %.100s", (u_int) pw->pw_uid, strerror(errno));
+		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
+
+#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));
+#endif
+
+	/* Try restoration of GID if changed (test clearing of saved gid) */
+	if (old_gid != pw->pw_gid &&
+	    (setgid(old_gid) != -1 || setegid(old_gid) != -1))
+		fatal("%s: was able to restore old [e]gid", __func__);
+
+	/* 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);
+	}
 }