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|
#!/bin/sh
# SPDX-License-Identifier: GPL-2.0
#
# Loading a kernel image via the kexec_file_load syscall can verify either
# the IMA signature stored in the security.ima xattr or the PE signature,
# both signatures depending on the IMA policy, or none.
#
# To determine whether the kernel image is signed, this test depends
# on pesign and getfattr. This test also requires the kernel to be
# built with CONFIG_IKCONFIG enabled and either CONFIG_IKCONFIG_PROC
# enabled or access to the extract-ikconfig script.
TEST="KEXEC_FILE_LOAD"
. ./kexec_common_lib.sh
trap "{ rm -f $IKCONFIG ; }" EXIT
# Some of the IMA builtin policies may require the kexec kernel image to
# be signed, but these policy rules may be replaced with a custom
# policy. Only CONFIG_IMA_APPRAISE_REQUIRE_KEXEC_SIGS persists after
# loading a custom policy. Check if it is enabled, before reading the
# IMA runtime sysfs policy file.
# Return 1 for IMA signature required and 0 for not required.
is_ima_sig_required()
{
local ret=0
kconfig_enabled "CONFIG_IMA_APPRAISE_REQUIRE_KEXEC_SIGS=y" \
"IMA kernel image signature required"
if [ $? -eq 1 ]; then
log_info "IMA signature required"
return 1
fi
# The architecture specific or a custom policy may require the
# kexec kernel image be signed. Policy rules are walked
# sequentially. As a result, a policy rule may be defined, but
# might not necessarily be used. This test assumes if a policy
# rule is specified, that is the intent.
# First check for appended signature (modsig), then xattr
if [ $ima_read_policy -eq 1 ]; then
check_ima_policy "appraise" "func=KEXEC_KERNEL_CHECK" \
"appraise_type=imasig|modsig"
ret=$?
if [ $ret -eq 1 ]; then
log_info "IMA or appended(modsig) signature required"
else
check_ima_policy "appraise" "func=KEXEC_KERNEL_CHECK" \
"appraise_type=imasig"
ret=$?
[ $ret -eq 1 ] && log_info "IMA signature required";
fi
fi
return $ret
}
# The kexec_file_load_test() is complicated enough, require pesign.
# Return 1 for PE signature found and 0 for not found.
check_for_pesig()
{
which pesign > /dev/null 2>&1 || log_skip "pesign not found"
pesign -i $KERNEL_IMAGE --show-signature | grep -q "No signatures"
local ret=$?
if [ $ret -eq 1 ]; then
log_info "kexec kernel image PE signed"
else
log_info "kexec kernel image not PE signed"
fi
return $ret
}
# The kexec_file_load_test() is complicated enough, require getfattr.
# Return 1 for IMA signature found and 0 for not found.
check_for_imasig()
{
local ret=0
which getfattr > /dev/null 2>&1
if [ $? -eq 1 ]; then
log_skip "getfattr not found"
fi
line=$(getfattr -n security.ima -e hex --absolute-names $KERNEL_IMAGE 2>&1)
echo $line | grep -q "security.ima=0x03"
if [ $? -eq 0 ]; then
ret=1
log_info "kexec kernel image IMA signed"
else
log_info "kexec kernel image not IMA signed"
fi
return $ret
}
# Return 1 for appended signature (modsig) found and 0 for not found.
check_for_modsig()
{
local module_sig_string="~Module signature appended~"
local sig="$(tail --bytes $((${#module_sig_string} + 1)) $KERNEL_IMAGE)"
local ret=0
if [ "$sig" == "$module_sig_string" ]; then
ret=1
log_info "kexec kernel image modsig signed"
else
log_info "kexec kernel image not modsig signed"
fi
return $ret
}
kexec_file_load_test()
{
local succeed_msg="kexec_file_load succeeded"
local failed_msg="kexec_file_load failed"
local key_msg="try enabling the CONFIG_INTEGRITY_PLATFORM_KEYRING"
line=$(kexec --load --kexec-file-syscall $KERNEL_IMAGE 2>&1)
if [ $? -eq 0 ]; then
kexec --unload --kexec-file-syscall
# In secureboot mode with an architecture specific
# policy, make sure either an IMA or PE signature exists.
if [ $secureboot -eq 1 ] && [ $arch_policy -eq 1 ] && \
[ $ima_signed -eq 0 ] && [ $pe_signed -eq 0 ] \
&& [ $ima_modsig -eq 0 ]; then
log_fail "$succeed_msg (missing sig)"
fi
if [ $kexec_sig_required -eq 1 -o $pe_sig_required -eq 1 ] \
&& [ $pe_signed -eq 0 ]; then
log_fail "$succeed_msg (missing PE sig)"
fi
if [ $ima_sig_required -eq 1 ] && [ $ima_signed -eq 0 ] \
&& [ $ima_modsig -eq 0 ]; then
log_fail "$succeed_msg (missing IMA sig)"
fi
if [ $pe_sig_required -eq 0 ] && [ $ima_appraise -eq 1 ] \
&& [ $ima_sig_required -eq 0 ] && [ $ima_signed -eq 0 ] \
&& [ $ima_read_policy -eq 0 ]; then
log_fail "$succeed_msg (possibly missing IMA sig)"
fi
if [ $pe_sig_required -eq 0 ] && [ $ima_appraise -eq 0 ]; then
log_info "No signature verification required"
elif [ $pe_sig_required -eq 0 ] && [ $ima_appraise -eq 1 ] \
&& [ $ima_sig_required -eq 0 ] && [ $ima_signed -eq 0 ] \
&& [ $ima_read_policy -eq 1 ]; then
log_info "No signature verification required"
fi
log_pass "$succeed_msg"
fi
# Check the reason for the kexec_file_load failure
echo $line | grep -q "Required key not available"
if [ $? -eq 0 ]; then
if [ $platform_keyring -eq 0 ]; then
log_pass "$failed_msg (-ENOKEY), $key_msg"
else
log_pass "$failed_msg (-ENOKEY)"
fi
fi
if [ $kexec_sig_required -eq 1 -o $pe_sig_required -eq 1 ] \
&& [ $pe_signed -eq 0 ]; then
log_pass "$failed_msg (missing PE sig)"
fi
if [ $ima_sig_required -eq 1 ] && [ $ima_signed -eq 0 ]; then
log_pass "$failed_msg (missing IMA sig)"
fi
if [ $pe_sig_required -eq 0 ] && [ $ima_appraise -eq 1 ] \
&& [ $ima_sig_required -eq 0 ] && [ $ima_read_policy -eq 0 ] \
&& [ $ima_signed -eq 0 ]; then
log_pass "$failed_msg (possibly missing IMA sig)"
fi
log_pass "$failed_msg"
return 0
}
# kexec requires root privileges
require_root_privileges
# get the kernel config
get_kconfig
kconfig_enabled "CONFIG_KEXEC_FILE=y" "kexec_file_load is enabled"
if [ $? -eq 0 ]; then
log_skip "kexec_file_load is not enabled"
fi
# Determine which kernel config options are enabled
kconfig_enabled "CONFIG_IMA_APPRAISE=y" "IMA enabled"
ima_appraise=$?
kconfig_enabled "CONFIG_IMA_ARCH_POLICY=y" \
"architecture specific policy enabled"
arch_policy=$?
kconfig_enabled "CONFIG_INTEGRITY_PLATFORM_KEYRING=y" \
"platform keyring enabled"
platform_keyring=$?
kconfig_enabled "CONFIG_IMA_READ_POLICY=y" "reading IMA policy permitted"
ima_read_policy=$?
kconfig_enabled "CONFIG_KEXEC_SIG_FORCE=y" \
"kexec signed kernel image required"
kexec_sig_required=$?
kconfig_enabled "CONFIG_KEXEC_BZIMAGE_VERIFY_SIG=y" \
"PE signed kernel image required"
pe_sig_required=$?
is_ima_sig_required
ima_sig_required=$?
get_secureboot_mode
secureboot=$?
# Are there pe and ima signatures
check_for_pesig
pe_signed=$?
check_for_imasig
ima_signed=$?
check_for_modsig
ima_modsig=$?
# Test loading the kernel image via kexec_file_load syscall
kexec_file_load_test
|
