From 9ed3c05b23e4315992e9a5a6554b2869ef9dc8e6 Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra@samba.org>
Date: Mon, 27 Mar 2017 10:46:47 -0700
Subject: [PATCH 1/2] s3: smbd: Fix incorrect logic exposed by fix for the
 security bug 12496 (CVE-2017-2619).

In a UNIX filesystem, the names "." and ".." by definition can *never*
be symlinks - they are already reserved names.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12721

Signed-off-by: Jeremy Allison <jra@samba.org>
---
 source3/smbd/vfs.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/source3/smbd/vfs.c b/source3/smbd/vfs.c
index 35f560b8676..5133fe5c2fd 100644
--- a/source3/smbd/vfs.c
+++ b/source3/smbd/vfs.c
@@ -1307,8 +1307,11 @@ NTSTATUS check_reduced_name(connection_struct *conn, const char *fname)
 			/* fname can't have changed in resolved_path. */
 			const char *p = &resolved_name[rootdir_len];
 
-			/* *p can be '\0' if fname was "." */
-			if (*p == '\0' && ISDOT(fname)) {
+			/*
+			 * UNIX filesystem semantics, names consisting
+			 * only of "." or ".." CANNOT be symlinks.
+			 */
+			if (ISDOT(fname) || ISDOTDOT(fname)) {
 				goto out;
 			}
 
-- 
2.12.1.578.ge9c3154ca4-goog


From 87c7b8a440be9a3fcab829c8e6e8c0a63c20a2f8 Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra@samba.org>
Date: Mon, 27 Mar 2017 11:48:25 -0700
Subject: [PATCH 2/2] s3: Test for CVE-2017-2619 regression with "follow
 symlinks = no".

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12721

Signed-off-by: Jeremy Allison <jra@samba.org>
---
 selftest/target/Samba3.pm                 |  8 ++++
 source3/script/tests/test_smbclient_s3.sh | 73 +++++++++++++++++++++++++++++++
 2 files changed, 81 insertions(+)

diff --git a/selftest/target/Samba3.pm b/selftest/target/Samba3.pm
index d754b5f9ac1..354f1527a70 100755
--- a/selftest/target/Samba3.pm
+++ b/selftest/target/Samba3.pm
@@ -1245,6 +1245,9 @@ sub provision($$$$$$$$)
 	my $shadow_shrdir="$shadow_basedir/share";
 	push(@dirs,$shadow_shrdir);
 
+	my $nosymlinks_shrdir="$shrdir/nosymlinks";
+	push(@dirs,$nosymlinks_shrdir);
+
 	# this gets autocreated by winbindd
 	my $wbsockdir="$prefix_abs/winbindd";
 
@@ -1861,6 +1864,11 @@ sub provision($$$$$$$$)
 	copy = tmp
         mangled names = illegal
 
+[nosymlinks]
+	copy = tmp
+	path = $nosymlinks_shrdir
+	follow symlinks = no
+
 [kernel_oplocks]
 	copy = tmp
 	kernel oplocks = yes
diff --git a/source3/script/tests/test_smbclient_s3.sh b/source3/script/tests/test_smbclient_s3.sh
index 22849bd5031..7d86a6134ae 100755
--- a/source3/script/tests/test_smbclient_s3.sh
+++ b/source3/script/tests/test_smbclient_s3.sh
@@ -1096,6 +1096,75 @@ EOF
     fi
 }
 
+# Test follow symlinks can't access symlinks
+test_nosymlinks()
+{
+# Setup test dirs.
+    slink_name="$LOCAL_PATH/nosymlinks/source"
+    slink_target="$LOCAL_PATH/nosymlinks/target"
+    mkdir_target="$LOCAL_PATH/nosymlinks/a"
+
+    rm -f $slink_target
+    rm -f $slink_name
+    rm -rf $mkdir_target
+
+    touch $slink_target
+    ln -s $slink_target $slink_name
+
+# Getting a file through a symlink name should fail.
+    tmpfile=$PREFIX/smbclient_interactive_prompt_commands
+    cat > $tmpfile <<EOF
+get source
+quit
+EOF
+    cmd='CLI_FORCE_INTERACTIVE=yes $SMBCLIENT "$@" -U$USERNAME%$PASSWORD //$SERVER/nosymlinks -I $SERVER_IP $ADDARGS < $tmpfile 2>&1'
+    eval echo "$cmd"
+    out=`eval $cmd`
+    ret=$?
+    rm -f $tmpfile
+
+    if [ $ret != 0 ] ; then
+       echo "$out"
+       echo "failed accessing nosymlinks with error $ret"
+       false
+       return
+    fi
+
+    echo "$out" | grep 'NT_STATUS_ACCESS_DENIED'
+    ret=$?
+    if [ $ret != 0 ] ; then
+       echo "$out"
+       echo "failed - should get NT_STATUS_ACCESS_DENIED getting \\nosymlinks\\source"
+       false
+    fi
+
+# But we should be able to create and delete directories.
+    cat > $tmpfile <<EOF
+mkdir a
+mkdir a\\b
+quit
+EOF
+    cmd='CLI_FORCE_INTERACTIVE=yes $SMBCLIENT "$@" -U$USERNAME%$PASSWORD //$SERVER/nosymlinks -I $SERVER_IP $ADDARGS < $tmpfile 2>&1'
+    eval echo "$cmd"
+    out=`eval $cmd`
+    ret=$?
+    rm -f $tmpfile
+
+    if [ $ret != 0 ] ; then
+       echo "$out"
+       echo "failed accessing nosymlinks with error $ret"
+       false
+       return
+    fi
+
+    echo "$out" | grep 'NT_STATUS'
+    ret=$?
+    if [ $ret == 0 ] ; then
+	echo "$out"
+	echo "failed - NT_STATUS_XXXX doing mkdir a; mkdir a\\b on \\nosymlinks"
+	false
+    fi
+}
 
 LOGDIR_PREFIX=test_smbclient_s3
 
@@ -1196,6 +1265,10 @@ testit "streams_depot can delete correctly" \
     test_streams_depot_delete || \
     failed=`expr $failed + 1`
 
+testit "follow symlinks = no" \
+    test_nosymlinks || \
+    failed=`expr $failed + 1`
+
 testit "rm -rf $LOGDIR" \
     rm -rf $LOGDIR || \
     failed=`expr $failed + 1`
-- 
2.12.1.578.ge9c3154ca4-goog