Support Illumos/Solaris fine-grained privileges

Includes a pre-auth privsep sandbox and several pledge()
emulations. bz#2511, patch by Alex Wilson.

ok dtucker@

1 files changed, 12 insertions, 6 deletions

diff --git a/uidswap.c b/uidswap.c
index 0702e1d9e..8bf6b244e 100644
--- a/uidswap.c
+++ b/uidswap.c
@@ -134,7 +134,7 @@ temporarily_use_uid(struct passwd *pw)
 void
 permanently_drop_suid(uid_t uid)
 {
-#ifndef HAVE_CYGWIN
+#ifndef NO_UID_RESTORATION_TEST
         uid_t old_uid = getuid();
 #endif
 
@@ -142,8 +142,14 @@ permanently_drop_suid(uid_t uid)
         if (setresuid(uid, uid, uid) < 0)
                 fatal("setresuid %u: %.100s", (u_int)uid, strerror(errno));
 
-#ifndef HAVE_CYGWIN
-        /* Try restoration of UID if changed (test clearing of saved uid) */
+#ifndef NO_UID_RESTORATION_TEST
+        /*
+         * Try restoration of UID if changed (test clearing of saved uid).
+         *
+         * Note that we don't do this on Cygwin, or on Solaris-based platforms
+         * where fine-grained privileges are available (the user might be
+         * deliberately allowed the right to setuid back to root).
+         */
         if (old_uid != uid &&
             (setuid(old_uid) != -1 || seteuid(old_uid) != -1))
                 fatal("%s: was able to restore old [e]uid", __func__);
@@ -199,7 +205,7 @@ restore_uid(void)
 void
 permanently_set_uid(struct passwd *pw)
 {
-#ifndef HAVE_CYGWIN
+#ifndef NO_UID_RESTORATION_TEST
         uid_t old_uid = getuid();
         gid_t old_gid = getgid();
 #endif
@@ -227,7 +233,7 @@ permanently_set_uid(struct passwd *pw)
         if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) < 0)
                 fatal("setresuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno));
 
-#ifndef HAVE_CYGWIN
+#ifndef NO_UID_RESTORATION_TEST
         /* 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))
@@ -241,7 +247,7 @@ permanently_set_uid(struct passwd *pw)
                     (u_int)pw->pw_gid);
         }
 
-#ifndef HAVE_CYGWIN
+#ifndef NO_UID_RESTORATION_TEST
         /* 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))