1 files changed, 64 insertions, 37 deletions

diff --git a/uidswap.c b/uidswap.c
index bdfa484fc..7cfacd4a5 100644
--- a/uidswap.c
+++ b/uidswap.c
@@ -12,7 +12,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: uidswap.c,v 1.13 2001/01/21 19:06:01 markus Exp $");
+RCSID("$OpenBSD: uidswap.c,v 1.14 2001/04/06 21:00:16 markus Exp $");
 
 #include "log.h"
 #include "uidswap.h"
@@ -26,57 +26,80 @@ RCSID("$OpenBSD: uidswap.c,v 1.13 2001/01/21 19:06:01 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;
-#endif
-
+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. */
-        saved_euid = geteuid();
-
-        /* 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_SETEUID */
-        /* 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 */
+        /* 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)
+                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.
  */
 void
 restore_uid(void)
 {
-#ifdef SAVED_IDS_WORK_WITH_SETEUID
+        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 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;
 }
 
 /*
@@ -84,8 +107,12 @@ restore_uid(void)
  * 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 (setuid(pw->pw_uid) < 0)
+                fatal("setuid %u: %.100s", (u_int) pw->pw_uid, strerror(errno));
+        if (setgid(pw->pw_gid) < 0)
+                fatal("setgid %u: %.100s", (u_int) pw->pw_gid, strerror(errno));
 }