From 9c96c5d4ca376b998be9919e70f74d0995c4df2e Mon Sep 17 00:00:00 2001
From: Panu Matilainen <pmatilai@redhat.com>
Date: Fri, 15 Sep 2023 14:38:35 +0300
Subject: [PATCH] Axe the experimental non-privileged chroot support from
 b4c832ca

While the chroot call itself works nicely for a regular user with this,
user/group mapping does not and cannot be made to work, because that
requires a fork and we cannot very well fork the process from deep down
here.

Better to put the irrepairable thing out of its misery, users are far
better of wrapping rpm with the unshare command instead.
---
 lib/poptALL.c    |  4 ----
 lib/rpmchroot.c  | 59 ------------------------------------------------
 tests/atlocal.in |  3 +--
 3 files changed, 1 insertion(+), 65 deletions(-)

diff --git a/lib/poptALL.c b/lib/poptALL.c
index b24c13ed78..4cf82ea05c 100644
--- a/lib/poptALL.c
+++ b/lib/poptALL.c
@@ -24,8 +24,6 @@
 
 static int _debug = 0;
 
-extern int _rpm_nouserns;
-
 extern int _fsm_debug;
 
 extern int _print_pkts;
@@ -272,8 +270,6 @@ struct poptOption rpmcliAllPoptTable[] = {
 	NULL, NULL},
  { "rpmiodebug", '\0', POPT_ARG_VAL|POPT_ARGFLAG_DOC_HIDDEN, &_rpmio_debug, -1,
 	N_("debug rpmio I/O"), NULL},
- { "nouserns", '\0', POPT_ARG_VAL|POPT_ARGFLAG_DOC_HIDDEN, &_rpm_nouserns, -1,
-	N_("disable user namespace support"), NULL},
  { "stats", '\0', POPT_ARG_VAL|POPT_ARGFLAG_DOC_HIDDEN, &_rpmts_stats, -1,
 	NULL, NULL},
 
diff --git a/lib/rpmchroot.c b/lib/rpmchroot.c
index ebcece6c25..ea0cea68a7 100644
--- a/lib/rpmchroot.c
+++ b/lib/rpmchroot.c
@@ -8,8 +8,6 @@
 #include "rpmug.h"
 #include "debug.h"
 
-int _rpm_nouserns = 0;
-
 struct rootState_s {
     char *rootDir;
     int chrootDone;
@@ -23,60 +21,6 @@ static struct rootState_s rootState = {
    .cwd = -1,
 }; 
 
-#if defined(HAVE_UNSHARE) && defined(CLONE_NEWUSER)
-/*
- * If setgroups file exists (Linux >= 3.19), we need to write "deny" to it,
- * otherwise gid_map will fail.
- */
-static int deny_setgroups(void)
-{
-    int fd = open("/proc/self/setgroups", O_WRONLY, 0);
-    int xx = -1;
-    if (fd >= 0) {
-	xx = write(fd, "deny\n", strlen("deny\n"));
-	close (fd);
-    }
-    return (xx == -1);
-}
-
-static int setup_map(const char *path, unsigned int id, unsigned int oid)
-{
-    int xx = -1;
-    int fd = open(path, O_WRONLY);
-    if (fd >= 0) {
-	char buf[256];
-	int ret = snprintf(buf, sizeof(buf), "%u %u 1\n", id, oid);
-	xx = write(fd, buf, ret);
-	close (fd);
-    }
-    return (xx == -1);
-}
-
-/*
- * Try to become root by creating a user namespace. We don't really care
- * if this fails here because in that case chroot() will just fail as it
- * normally would.
- */
-static void try_become_root(void)
-{
-    static int unshared = 0;
-    uid_t uid = getuid();
-    gid_t gid = getgid();
-    if (!unshared && unshare(CLONE_NEWUSER | CLONE_NEWNS) == 0) {
-	deny_setgroups();
-	setup_map("/proc/self/uid_map", 0, uid);
-	setup_map("/proc/self/gid_map", 0, gid);
-	unshared = 1;
-    }
-    rpmlog(RPMLOG_DEBUG, "user ns: %d original user %d:%d current %d:%d\n",
-	    unshared, uid, gid, getuid(), getgid());
-}
-#else
-static void try_become_root(void)
-{
-}
-#endif
-
 int rpmChrootSet(const char *rootDir)
 {
     int rc = 0;
@@ -126,9 +70,6 @@ int rpmChrootIn(void)
     if (rootState.chrootDone > 0) {
 	rootState.chrootDone++;
     } else if (rootState.chrootDone == 0) {
-	if (!_rpm_nouserns && getuid())
-	    try_become_root();
-
 	rpmlog(RPMLOG_DEBUG, "entering chroot %s\n", rootState.rootDir);
 	if (chdir("/") == 0 && chroot(rootState.rootDir) == 0) {
 	    rootState.chrootDone = 1;
diff --git a/tests/atlocal.in b/tests/atlocal.in
index 753bce1ae6..0c46a47334 100644
--- a/tests/atlocal.in
+++ b/tests/atlocal.in
@@ -150,8 +150,7 @@ function runroot()
     setup_env
     snapshot exec "$@" \
              --define "_buildhost testhost" \
-             --define "_topdir /build" \
-             --nouserns
+             --define "_topdir /build"
 }
 
 function runroot_other()