[bpf-next,v3,2/2] selftests/bpf: Add test for bpftool access to read-only protected maps

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index cf5ed3bee573..731a86407799 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -109,6 +109,7 @@  TEST_PROGS := test_kmod.sh \
 	test_xdping.sh \
 	test_bpftool_build.sh \
 	test_bpftool.sh \
+	test_bpftool_map.sh \
 	test_bpftool_metadata.sh \
 	test_doc_build.sh \
 	test_xsk.sh \
diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_map_elem.c b/tools/testing/selftests/bpf/progs/bpf_iter_map_elem.c
new file mode 100644
index 000000000000..2f20485e0de3
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_map_elem.c
@@ -0,0 +1,22 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include "vmlinux.h"
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_helpers.h>
+
+char _license[] SEC("license") = "GPL";
+
+__u32 value_sum = 0;
+
+SEC("iter/bpf_map_elem")
+int dump_bpf_map_values(struct bpf_iter__bpf_map_elem *ctx)
+{
+	__u32 value = 0;
+
+	if (ctx->value == (void *)0)
+		return 0;
+
+	bpf_probe_read_kernel(&value, sizeof(value), ctx->value);
+	value_sum += value;
+	return 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/security_bpf_map.c b/tools/testing/selftests/bpf/progs/security_bpf_map.c
new file mode 100644
index 000000000000..7176f8468641
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/security_bpf_map.c
@@ -0,0 +1,69 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include "vmlinux.h"
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_helpers.h>
+
+char _license[] SEC("license") = "GPL";
+
+#define EPERM 1 /* Operation not permitted */
+
+/* From include/linux/mm.h. */
+#define FMODE_WRITE	0x2
+
+struct map;
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__type(key, __u32);
+	__type(value, __u32);
+	__uint(max_entries, 1);
+} prot_status_map SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__type(key, __u32);
+	__type(value, __u32);
+	__uint(max_entries, 3);
+} prot_map SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__type(key, __u32);
+	__type(value, __u32);
+	__uint(max_entries, 3);
+} not_prot_map SEC(".maps");
+
+SEC("fmod_ret/security_bpf_map")
+int BPF_PROG(fmod_bpf_map, struct bpf_map *map, int fmode)
+{
+	__u32 key = 0;
+	__u32 *status_ptr = bpf_map_lookup_elem(&prot_status_map, &key);
+	if (!status_ptr || !*status_ptr) {
+		return 0;
+	}
+
+	if (map == &prot_map) {
+		/* Allow read-only access */
+		if (fmode & FMODE_WRITE)
+			return -EPERM;
+	}
+
+	return 0;
+}
+
+/*
+ * This program keeps references to maps. This is needed to prevent
+ * optimizing them out.
+ */
+SEC("fentry/bpf_fentry_test1")
+int BPF_PROG(fentry_dummy1, int a)
+{
+	__u32 key = 0;
+	__u32 val1 = a;
+	__u32 val2 = a + 1;
+
+	bpf_map_update_elem(&prot_map, &key, &val1, BPF_ANY);
+	bpf_map_update_elem(&not_prot_map, &key, &val2, BPF_ANY);
+	return 0;
+}
diff --git a/tools/testing/selftests/bpf/test_bpftool_map.sh b/tools/testing/selftests/bpf/test_bpftool_map.sh
new file mode 100755
index 000000000000..383e4df08f93
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_bpftool_map.sh
@@ -0,0 +1,363 @@ 
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+
+TESTNAME="bpftool_map"
+BPF_FILE="security_bpf_map.bpf.o"
+BPF_ITER_FILE="bpf_iter_map_elem.bpf.o"
+PROTECTED_MAP_NAME="prot_map"
+NOT_PROTECTED_MAP_NAME="not_prot_map"
+BPF_FS_TMP_PARENT="/tmp"
+BPF_FS_PARENT=$(awk '$3 == "bpf" {print $2; exit}' /proc/mounts)
+BPF_FS_PARENT=${BPF_FS_PARENT:-$BPF_FS_TMP_PARENT}
+# bpftool will mount bpf file system under BPF_DIR if it is not mounted
+# under BPF_FS_PARENT.
+BPF_DIR="$BPF_FS_PARENT/test_$TESTNAME"
+SCRIPT_DIR=$(dirname $(realpath "$0"))
+BPF_FILE_PATH="$SCRIPT_DIR/$BPF_FILE"
+BPF_ITER_FILE_PATH="$SCRIPT_DIR/$BPF_ITER_FILE"
+BPFTOOL_PATH="bpftool"
+# Assume the script is located under tools/testing/selftests/bpf/
+KDIR_ROOT_DIR=$(realpath "$SCRIPT_DIR"/../../../../)
+
+_cleanup()
+{
+	set +eu
+
+	# If BPF_DIR is a mount point this will not remove the mount point itself.
+	[ -d "$BPF_DIR" ] && rm -rf "$BPF_DIR" 2> /dev/null
+
+	# Unmount if BPF filesystem was temporarily created.
+	if [ "$BPF_FS_PARENT" = "$BPF_FS_TMP_PARENT" ]; then
+		# A loop and recursive unmount are required as bpftool might
+		# create multiple mounts. For example, a bind mount of the directory
+		# to itself. The bind mount is created to change mount propagation
+		# flags on an actual mount point.
+		max_attempts=3
+		attempt=0
+		while mountpoint -q "$BPF_DIR" && [ $attempt -lt $max_attempts ]; do
+			umount -R "$BPF_DIR" 2>/dev/null
+			attempt=$((attempt+1))
+		done
+
+		# The directory still exists. Remove it now.
+		[ -d "$BPF_DIR" ] && rm -rf "$BPF_DIR" 2>/dev/null
+	fi
+}
+
+cleanup_skip()
+{
+	echo "selftests: $TESTNAME [SKIP]"
+	_cleanup
+
+	exit $ksft_skip
+}
+
+cleanup()
+{
+	if [ "$?" = 0 ]; then
+		echo "selftests: $TESTNAME [PASS]"
+	else
+		echo "selftests: $TESTNAME [FAILED]"
+	fi
+	_cleanup
+}
+
+check_root_privileges() {
+	if [ $(id -u) -ne 0 ]; then
+		echo "Need root privileges"
+		exit $ksft_skip
+	fi
+}
+
+# Function to verify bpftool path.
+# Parameters:
+#   $1: bpftool path
+verify_bpftool_path() {
+	local bpftool_path="$1"
+	if ! "$bpftool_path" version > /dev/null 2>&1; then
+		echo "Could not run test without bpftool"
+		exit $ksft_skip
+	fi
+}
+
+# Function to initialize map entries with keys [0..2] and values set to 0.
+# Parameters:
+#  $1: Map name
+#  $2: bpftool path
+initialize_map_entries() {
+	local map_name="$1"
+	local bpftool_path="$2"
+
+	for key in 0 1 2; do
+		"$bpftool_path" map update name "$map_name" key $key 0 0 0 value 0 0 0 $key
+	done
+}
+
+# Test read access to the map.
+# Parameters:
+#   $1: Name command (name/pinned)
+#   $2: Map name
+#   $3: bpftool path
+#   $4: key
+access_for_read() {
+	local name_cmd="$1"
+	local map_name="$2"
+	local bpftool_path="$3"
+	local key="$4"
+
+	# Test read access to the map.
+	if ! "$bpftool_path" map lookup "$name_cmd" "$map_name" key $key 1>/dev/null; then
+		echo "  Read access to $key in $map_name failed"
+		exit 1
+	fi
+}
+
+# Test write access to the map.
+# Parameters:
+#   $1: Name command (name/pinned)
+#   $2: Map name
+#   $3: bpftool path
+#   $4: key
+#   $5: Whether write should succeed (true/false)
+access_for_write() {
+	local name_cmd="$1"
+	local map_name="$2"
+	local bpftool_path="$3"
+	local key="$4"
+	local write_should_succeed="$5"
+	local value="1 1 1 1"
+
+	if "$bpftool_path" map update "$name_cmd" "$map_name" key $key value $value 2>/dev/null; then
+		if [ "$write_should_succeed" = "false" ]; then
+			echo "  Write access to $key in $map_name succeeded but should have failed"
+			exit 1
+		fi
+	else
+		if [ "$write_should_succeed" = "true" ]; then
+			echo "  Write access to $key in $map_name failed but should have succeeded"
+			exit 1
+		fi
+	fi
+}
+
+# Test entry deletion for the map.
+# Parameters:
+#   $1: Name command (name/pinned)
+#   $2: Map name
+#   $3: bpftool path
+#   $4: key
+#   $5: Whether write should succeed (true/false)
+access_for_deletion() {
+	local name_cmd="$1"
+	local map_name="$2"
+	local bpftool_path="$3"
+	local key="$4"
+	local write_should_succeed="$5"
+	local value="1 1 1 1"
+
+	# Test deletion by key for the map.
+	# Before deleting, check the key exists.
+	if ! "$bpftool_path" map lookup "$name_cmd" "$map_name" key $key 1>/dev/null; then
+		echo "  Key $key does not exist in $map_name"
+		exit 1
+	fi
+
+	# Delete by key.
+	if "$bpftool_path" map delete "$name_cmd" "$map_name" key $key 2>/dev/null; then
+		if [ "$write_should_succeed" = "false" ]; then
+			echo "  Deletion for $key in $map_name succeeded but should have failed"
+			exit 1
+		fi
+	else
+		if [ "$write_should_succeed" = "true" ]; then
+			echo "  Deletion for $key in $map_name failed but should have succeeded"
+			exit 1
+		fi
+	fi
+
+	# After deleting, check the entry existence according to the expected status.
+	if "$bpftool_path" map lookup "$name_cmd" "$map_name" key $key 1>/dev/null; then
+		if [ "$write_should_succeed" = "true" ]; then
+			echo "  Key $key for $map_name was not deleted but should have been deleted"
+			exit 1
+		fi
+	else
+		if [ "$write_should_succeed" = "false" ]; then
+			echo "  Key $key for $map_name was deleted but should have not been deleted"
+			exit 1
+		fi
+	fi
+
+	# Test creation of map's deleted entry, if deletion was successfull.
+	# Otherwise, the entry exists.
+	if "$bpftool_path" map update "$name_cmd" "$map_name" key $key value $value 2>/dev/null; then
+		if [ "$write_should_succeed" = "false" ]; then
+			echo "  Write access to $key in $map_name succeeded after deletion attempt but should have failed"
+			exit 1
+		fi
+	else
+		if [ "$write_should_succeed" = "true" ]; then
+			echo "  Write access to $key in $map_name failed after deletion attempt but should have succeeded"
+			exit 1
+		fi
+	fi
+}
+
+# Test map elements iterator.
+# Parameters:
+#   $1: Name command (name/pinned)
+#   $2: Map name
+#   $3: bpftool path
+#   $4: BPF_DIR
+#   $5: bpf iterator object file path
+iterate_map_elem() {
+	local name_cmd="$1"
+	local map_name="$2"
+	local bpftool_path="$3"
+	local bpf_dir="$4"
+	local bpf_file="$5"
+	local pin_path="$bpf_dir/map_iterator"
+
+	"$bpftool_path" iter pin "$bpf_file" "$pin_path" map "$name_cmd" "$map_name"
+	if [ ! -f "$pin_path" ]; then
+		echo "  Failed to pin iterator to $pin_path"
+		exit 1
+	fi
+
+	cat "$pin_path" 1>/dev/null
+	rm "$pin_path" 2>/dev/null
+}
+
+# Function to test map access with configurable write expectations
+# Parameters:
+#   $1: Name command (name/pinned)
+#   $2: Map name
+#   $3: bpftool path
+#   $4: key for rw
+#   $5: key to delete
+#   $6: Whether write should succeed (true/false)
+#   $7: BPF_DIR
+#   $8: bpf iterator object file path
+access_map() {
+	local name_cmd="$1"
+	local map_name="$2"
+	local bpftool_path="$3"
+	local key_for_rw="$4"
+	local key_to_del="$5"
+	local write_should_succeed="$6"
+	local bpf_dir="$7"
+	local bpf_iter_file_path="$8"
+
+	access_for_read "$name_cmd" "$map_name" "$bpftool_path" "$key_for_rw"
+	access_for_write "$name_cmd" "$map_name" "$bpftool_path" "$key_for_rw" \
+		"$write_should_succeed"
+	access_for_deletion "$name_cmd" "$map_name" "$bpftool_path" "$key_to_del" \
+		"$write_should_succeed"
+	iterate_map_elem "$name_cmd" "$map_name" "$bpftool_path" "$bpf_dir" \
+		"$bpf_iter_file_path"
+}
+
+# Function to test map access with configurable write expectations
+# Parameters:
+#   $1: Map name
+#   $2: bpftool path
+#   $3: BPF_DIR
+#   $4: Whether write should succeed (true/false)
+#   $5: bpf iterator object file path
+test_map_access() {
+	local map_name="$1"
+	local bpftool_path="$2"
+	local bpf_dir="$3"
+	local pin_path="$bpf_dir/${map_name}_pinned"
+	local write_should_succeed="$4"
+	local bpf_iter_file_path="$5"
+
+	# Test access to the map by name.
+	access_map "name" "$map_name" "$bpftool_path" "0 0 0 0" "1 0 0 0" \
+		"$write_should_succeed" "$bpf_dir" "$bpf_iter_file_path"
+
+	# Pin the map to the BPF filesystem
+	"$bpftool_path" map pin name "$map_name" "$pin_path"
+	if [ ! -e "$pin_path" ]; then
+		echo "  Failed to pin $map_name"
+		exit 1
+	fi
+
+	# Test access to the pinned map.
+	access_map "pinned" "$pin_path" "$bpftool_path" "0 0 0 0" "2 0 0 0" \
+		"$write_should_succeed" "$bpf_dir" "$bpf_iter_file_path"
+}
+
+# Function to test map creation and map-of-maps
+# Parameters:
+#   $1: bpftool path
+#   $2: BPF_DIR
+test_map_creation_and_map_of_maps() {
+	local bpftool_path="$1"
+	local bpf_dir="$2"
+	local outer_map_name="outer_map_tt"
+	local inner_map_name="inner_map_tt"
+
+	"$bpftool_path" map create "$bpf_dir/$inner_map_name" type array key 4 \
+		value 4 entries 4 name "$inner_map_name"
+	if [ ! -f "$bpf_dir/$inner_map_name" ]; then
+		echo " Failed to create inner map file at $bpf_dir/$outer_map_name"
+		return 1
+	fi
+
+	"$bpftool_path" map create "$bpf_dir/$outer_map_name" type hash_of_maps \
+		key 4 value 4 entries 2 name "$outer_map_name" inner_map name "$inner_map_name"
+	if [ ! -f "$bpf_dir/$outer_map_name" ]; then
+		echo " Failed to create outer map file at $bpf_dir/$outer_map_name"
+		return 1
+	fi
+
+	# Add entries to the outer map by name and by pinned path.
+	"$bpftool_path" map update pinned "$bpf_dir/$outer_map_name" key 0 0 0 0 \
+		value pinned "$bpf_dir/$inner_map_name"
+	"$bpftool_path" map update name "$outer_map_name" key 1 0 0 0 value \
+		name "$inner_map_name"
+
+	# The outer map should be full by now.
+	# The following map update command is expected to fail.
+	if "$bpftool_path" map update name "$outer_map_name" key 2 0 0 0 value name \
+		"$inner_map_name" 2>/dev/null; then
+		echo "  Update for $outer_map_name succeeded but should have failed"
+		exit 1
+	fi
+}
+
+set -eu
+
+trap cleanup_skip EXIT
+
+check_root_privileges
+
+verify_bpftool_path "$BPFTOOL_PATH"
+
+trap cleanup EXIT
+
+# Load and attach the BPF programs to control maps access.
+"$BPFTOOL_PATH" prog loadall "$BPF_FILE_PATH" "$BPF_DIR" autoattach
+
+initialize_map_entries "$PROTECTED_MAP_NAME" "$BPFTOOL_PATH"
+initialize_map_entries "$NOT_PROTECTED_MAP_NAME" "$BPFTOOL_PATH"
+
+# Activate the map protection mechanism. Protection status is controlled
+# by a value stored in the prot_status_map at index 0.
+"$BPFTOOL_PATH" map update name prot_status_map key 0 0 0 0 value 1 0 0 0
+
+# Test protected map (write should fail).
+test_map_access "$PROTECTED_MAP_NAME" "$BPFTOOL_PATH" "$BPF_DIR" "false" \
+ "$BPF_ITER_FILE_PATH"
+
+# Test not protected map (write should succeed).
+test_map_access "$NOT_PROTECTED_MAP_NAME" "$BPFTOOL_PATH" "$BPF_DIR" "true" \
+ "$BPF_ITER_FILE_PATH"
+
+test_map_creation_and_map_of_maps "$BPFTOOL_PATH" "$BPF_DIR"
+
+exit 0