[PATCH v4 1/2] ima: Align ima_file_mmap() parameters with mmap_file LSM hook

[PATCH v4 1/2] ima: Align ima_file_mmap() parameters with mmap_file LSM hook

[Roberto Sassu]

From: Roberto Sassu <roberto.sassu@huawei.com>

Commit 98de59bfe4b2f ("take calculation of final prot in
security_mmap_file() into a helper") moved the code to update prot, to be
the actual protections applied to the kernel, to a new helper called
mmap_prot().

However, while without the helper ima_file_mmap() was getting the updated
prot, with the helper ima_file_mmap() gets the original prot, which
contains the protections requested by the application.

A possible consequence of this change is that, if an application calls
mmap() with only PROT_READ, and the kernel applies PROT_EXEC in addition,
that application would have access to executable memory without having this
event recorded in the IMA measurement list. This situation would occur for
example if the application, before mmap(), calls the personality() system
call with READ_IMPLIES_EXEC as the first argument.

Align ima_file_mmap() parameters with those of the mmap_file LSM hook, so
that IMA can receive both the requested prot and the final prot. Since the
requested protections are stored in a new variable, and the final
protections are stored in the existing variable, this effectively restores
the original behavior of the MMAP_CHECK hook.

Cc: stable@vger.kernel.org
Fixes: 98de59bfe4b2 ("take calculation of final prot in security_mmap_file() into a helper")
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
---
 include/linux/ima.h               | 6 ++++--
 security/integrity/ima/ima_main.c | 7 +++++--
 security/security.c               | 7 ++++---
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/include/linux/ima.h b/include/linux/ima.h
index 5a0b2a285a18..d79fee67235e 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -21,7 +21,8 @@ extern int ima_file_check(struct file *file, int mask);
 extern void ima_post_create_tmpfile(struct user_namespace *mnt_userns,
 				    struct inode *inode);
 extern void ima_file_free(struct file *file);
-extern int ima_file_mmap(struct file *file, unsigned long prot);
+extern int ima_file_mmap(struct file *file, unsigned long reqprot,
+			 unsigned long prot, unsigned long flags);
 extern int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot);
 extern int ima_load_data(enum kernel_load_data_id id, bool contents);
 extern int ima_post_load_data(char *buf, loff_t size,
@@ -76,7 +77,8 @@ static inline void ima_file_free(struct file *file)
 	return;
 }
 
-static inline int ima_file_mmap(struct file *file, unsigned long prot)
+static inline int ima_file_mmap(struct file *file, unsigned long reqprot,
+				unsigned long prot, unsigned long flags)
 {
 	return 0;
 }
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 377300973e6c..f48f4e694921 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -397,7 +397,9 @@ static int process_measurement(struct file *file, const struct cred *cred,
 /**
  * ima_file_mmap - based on policy, collect/store measurement.
  * @file: pointer to the file to be measured (May be NULL)
- * @prot: contains the protection that will be applied by the kernel.
+ * @reqprot: protection requested by the application
+ * @prot: protection that will be applied by the kernel
+ * @flags: operational flags
  *
  * Measure files being mmapped executable based on the ima_must_measure()
  * policy decision.
@@ -405,7 +407,8 @@ static int process_measurement(struct file *file, const struct cred *cred,
  * On success return 0.  On integrity appraisal error, assuming the file
  * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
  */
-int ima_file_mmap(struct file *file, unsigned long prot)
+int ima_file_mmap(struct file *file, unsigned long reqprot,
+		  unsigned long prot, unsigned long flags)
 {
 	u32 secid;
 
diff --git a/security/security.c b/security/security.c
index d1571900a8c7..174afa4fad81 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1661,12 +1661,13 @@ static inline unsigned long mmap_prot(struct file *file, unsigned long prot)
 int security_mmap_file(struct file *file, unsigned long prot,
 			unsigned long flags)
 {
+	unsigned long prot_adj = mmap_prot(file, prot);
 	int ret;
-	ret = call_int_hook(mmap_file, 0, file, prot,
-					mmap_prot(file, prot), flags);
+
+	ret = call_int_hook(mmap_file, 0, file, prot, prot_adj, flags);
 	if (ret)
 		return ret;
-	return ima_file_mmap(file, prot);
+	return ima_file_mmap(file, prot, prot_adj, flags);
 }
 
 int security_mmap_addr(unsigned long addr)
-- 
2.25.1

[PATCH v4 2/2] ima: Introduce MMAP_CHECK_REQPROT hook

[Roberto Sassu]

From: Roberto Sassu <roberto.sassu@huawei.com>

Commit 98de59bfe4b2f ("take calculation of final prot in
security_mmap_file() into a helper") caused ima_file_mmap() to receive the
protections requested by the application and not those applied by the
kernel.

After restoring the original MMAP_CHECK behavior, existing attestation
servers might be broken due to not being ready to handle new entries
(previously missing) in the IMA measurement list.

Restore the original correct MMAP_CHECK behavior, instead of keeping the
current buggy one and introducing a new hook with the correct behavior.
Otherwise, there would have been the risk of IMA users not noticing the
problem at all, as they would actively have to update the IMA policy, to
switch to the correct behavior.

Also, introduce the new MMAP_CHECK_REQPROT hook to keep the current
behavior, so that IMA users could easily fix a broken attestation server,
although this approach is discouraged due to potentially missing
measurements.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
 Documentation/ABI/testing/ima_policy  |  2 +-
 security/integrity/ima/ima.h          |  1 +
 security/integrity/ima/ima_api.c      |  3 ++-
 security/integrity/ima/ima_appraise.c |  3 +++
 security/integrity/ima/ima_main.c     | 27 ++++++++++++++++++++++-----
 security/integrity/ima/ima_policy.c   |  4 ++++
 6 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy
index db17fc8a0c9f..49db0ff288e5 100644
--- a/Documentation/ABI/testing/ima_policy
+++ b/Documentation/ABI/testing/ima_policy
@@ -35,7 +35,7 @@ Description:
 				[FIRMWARE_CHECK]
 				[KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
 				[KEXEC_CMDLINE] [KEY_CHECK] [CRITICAL_DATA]
-				[SETXATTR_CHECK]
+				[SETXATTR_CHECK][MMAP_CHECK_REQPROT]
 			mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND]
 			       [[^]MAY_EXEC]
 			fsmagic:= hex value
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 03b440921e61..7186769d5e13 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -190,6 +190,7 @@ static inline unsigned int ima_hash_key(u8 *digest)
 	hook(NONE, none)				\
 	hook(FILE_CHECK, file)				\
 	hook(MMAP_CHECK, mmap)				\
+	hook(MMAP_CHECK_REQPROT, mmap_reqprot)		\
 	hook(BPRM_CHECK, bprm)				\
 	hook(CREDS_CHECK, creds)			\
 	hook(POST_SETATTR, post_setattr)		\
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index c1e76282b5ee..3e134c900f0c 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -179,7 +179,8 @@ void ima_add_violation(struct file *file, const unsigned char *filename,
  *		subj=, obj=, type=, func=, mask=, fsmagic=
  *	subj,obj, and type: are LSM specific.
  *	func: FILE_CHECK | BPRM_CHECK | CREDS_CHECK | MMAP_CHECK | MODULE_CHECK
- *	| KEXEC_CMDLINE | KEY_CHECK | CRITICAL_DATA
+ *	| KEXEC_CMDLINE | KEY_CHECK | CRITICAL_DATA | SETXATTR_CHECK
+ *	| MMAP_CHECK_REQPROT
  *	mask: contains the permission mask
  *	fsmagic: hex value
  *
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index ee6f7e237f2e..97c7d247315c 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -111,6 +111,7 @@ enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint,
 {
 	switch (func) {
 	case MMAP_CHECK:
+	case MMAP_CHECK_REQPROT:
 		return iint->ima_mmap_status;
 	case BPRM_CHECK:
 		return iint->ima_bprm_status;
@@ -131,6 +132,7 @@ static void ima_set_cache_status(struct integrity_iint_cache *iint,
 {
 	switch (func) {
 	case MMAP_CHECK:
+	case MMAP_CHECK_REQPROT:
 		iint->ima_mmap_status = status;
 		break;
 	case BPRM_CHECK:
@@ -155,6 +157,7 @@ static void ima_cache_flags(struct integrity_iint_cache *iint,
 {
 	switch (func) {
 	case MMAP_CHECK:
+	case MMAP_CHECK_REQPROT:
 		iint->flags |= (IMA_MMAP_APPRAISED | IMA_APPRAISED);
 		break;
 	case BPRM_CHECK:
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index f48f4e694921..58c2fd5fe22c 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -89,7 +89,8 @@ static int mmap_violation_check(enum ima_hooks func, struct file *file,
 	struct inode *inode;
 	int rc = 0;
 
-	if ((func == MMAP_CHECK) && mapping_writably_mapped(file->f_mapping)) {
+	if ((func == MMAP_CHECK || func == MMAP_CHECK_REQPROT) &&
+	    mapping_writably_mapped(file->f_mapping)) {
 		rc = -ETXTBSY;
 		inode = file_inode(file);
 
@@ -227,7 +228,8 @@ static int process_measurement(struct file *file, const struct cred *cred,
 	action = ima_get_action(file_mnt_user_ns(file), inode, cred, secid,
 				mask, func, &pcr, &template_desc, NULL,
 				&allowed_algos);
-	violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) &&
+	violation_check = ((func == FILE_CHECK || func == MMAP_CHECK ||
+			    func == MMAP_CHECK_REQPROT) &&
 			   (ima_policy_flag & IMA_MEASURE));
 	if (!action && !violation_check)
 		return 0;
@@ -411,12 +413,23 @@ int ima_file_mmap(struct file *file, unsigned long reqprot,
 		  unsigned long prot, unsigned long flags)
 {
 	u32 secid;
+	int ret;
 
-	if (file && (prot & PROT_EXEC)) {
-		security_current_getsecid_subj(&secid);
+	if (!file)
+		return 0;
+
+	security_current_getsecid_subj(&secid);
+
+	if (reqprot & PROT_EXEC) {
+		ret = process_measurement(file, current_cred(), secid, NULL,
+					  0, MAY_EXEC, MMAP_CHECK_REQPROT);
+		if (ret)
+			return ret;
+	}
+
+	if (prot & PROT_EXEC)
 		return process_measurement(file, current_cred(), secid, NULL,
 					   0, MAY_EXEC, MMAP_CHECK);
-	}
 
 	return 0;
 }
@@ -457,6 +470,10 @@ int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot)
 	action = ima_get_action(file_mnt_user_ns(vma->vm_file), inode,
 				current_cred(), secid, MAY_EXEC, MMAP_CHECK,
 				&pcr, &template, NULL, NULL);
+	action |= ima_get_action(file_mnt_user_ns(vma->vm_file), inode,
+				 current_cred(), secid, MAY_EXEC,
+				 MMAP_CHECK_REQPROT, &pcr, &template, NULL,
+				 NULL);
 
 	/* Is the mmap'ed file in policy? */
 	if (!(action & (IMA_MEASURE | IMA_APPRAISE_SUBMASK)))
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 6a68ec270822..419db81c4f67 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -697,6 +697,7 @@ static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func)
 
 	switch (func) {
 	case MMAP_CHECK:
+	case MMAP_CHECK_REQPROT:
 		return IMA_MMAP_APPRAISE;
 	case BPRM_CHECK:
 		return IMA_BPRM_APPRAISE;
@@ -1266,6 +1267,7 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
 	case NONE:
 	case FILE_CHECK:
 	case MMAP_CHECK:
+	case MMAP_CHECK_REQPROT:
 	case BPRM_CHECK:
 	case CREDS_CHECK:
 	case POST_SETATTR:
@@ -1504,6 +1506,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 			else if ((strcmp(args[0].from, "FILE_MMAP") == 0)
 				|| (strcmp(args[0].from, "MMAP_CHECK") == 0))
 				entry->func = MMAP_CHECK;
+			else if ((strcmp(args[0].from, "MMAP_CHECK_REQPROT") == 0))
+				entry->func = MMAP_CHECK_REQPROT;
 			else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
 				entry->func = BPRM_CHECK;
 			else if (strcmp(args[0].from, "CREDS_CHECK") == 0)
-- 
2.25.1

[PATCH ima-evm-utils v2] Add tests for MMAP_CHECK and MMAP_CHECK_REQPROT hooks

[Roberto Sassu]

From: Roberto Sassu <roberto.sassu@huawei.com>

Add tests to ensure that, after applying the kernel patch 'ima: Align
ima_file_mmap() parameters with mmap_file LSM hook', the MMAP_CHECK hook
checks the protections applied by the kernel and not those requested by the
application.

Also ensure that after applying 'ima: Introduce MMAP_CHECK_REQPROT hook',
the MMAP_CHECK_REQPROT hook checks the protections requested by the
application.

Test both with the test_mmap application that by default requests the
PROT_READ protection flag. Its syntax is:

test_mmap <file> <mode>

where mode can be:
- exec: adds the PROT_EXEC protection flag to mmap()
- read_implies_exec: calls the personality() system call with
                     READ_IMPLIES_EXEC as the first argument before mmap()
- mprotect: adds the PROT_EXEC protection flag to a memory area in addition
            to PROT_READ
- exec_on_writable: calls mmap() with PROT_EXEC on a file which has a
                    writable mapping

Check the different combinations of hooks/modes and ensure that a
measurement entry is found in the IMA measurement list only when it is
expected. No measurement entry should be found when only the PROT_READ
protection flag is requested or the matching policy rule has the
MMAP_CHECK_REQPROT hook and the personality() system call was called with
READ_IMPLIES_EXEC.

mprotect() with PROT_EXEC on an existing memory area protected with
PROT_READ should be denied (with an appraisal rule), regardless of the MMAP
hook specified in the policy. The same applies for mmap() with PROT_EXEC on
a file with a writable mapping.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
Changelog

v1:
- Declare PATCHES and uses new expect_pass_if() and expect_fail_if()
  (suggested by Stefan)
- Replace $FAIL with $HARDFAIL when the error occurs in the setup phase of
  the test (to not make an expect_fail test successful for other reasons
  than the focus of the test)
- Declare local variables in one line (suggested by Stefan)
- Print the test being executed at the beginning, so that the message
  always appears also if an error occurs
- Print the result of the tests in a separate line and separate the output
  of each test

 tests/Makefile.am     |   4 +-
 tests/mmap_check.test | 284 ++++++++++++++++++++++++++++++++++++++++++
 tests/test_mmap.c     |  75 +++++++++++
 3 files changed, 362 insertions(+), 1 deletion(-)
 create mode 100755 tests/mmap_check.test
 create mode 100644 tests/test_mmap.c

diff --git a/tests/Makefile.am b/tests/Makefile.am
index a0463b7b5b5d..ca9c4ca18380 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -2,7 +2,9 @@ check_SCRIPTS =
 TESTS = $(check_SCRIPTS)
 
 check_SCRIPTS += ima_hash.test sign_verify.test boot_aggregate.test \
-		 fsverity.test portable_signatures.test
+		 fsverity.test portable_signatures.test mmap_check.test
+
+check_PROGRAMS := test_mmap
 
 .PHONY: check_logs
 check_logs:
diff --git a/tests/mmap_check.test b/tests/mmap_check.test
new file mode 100755
index 000000000000..a045ee867437
--- /dev/null
+++ b/tests/mmap_check.test
@@ -0,0 +1,284 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 2022-2023 Roberto Sassu <roberto.sassu@huawei.com>
+#
+# Check the behavior of MMAP_CHECK and MMAP_CHECK_REQPROT
+
+trap '_report_exit_and_cleanup _cleanup_env cleanup' SIGINT SIGTERM SIGSEGV EXIT
+
+PATCHES=(
+'ima: Align ima_file_mmap() parameters with mmap_file LSM hook'
+'ima: Introduce MMAP_CHECK_REQPROT hook'
+)
+
+# Base VERBOSE on the environment variable, if set.
+VERBOSE="${VERBOSE:-0}"
+
+cd "$(dirname "$0")" || exit "$FAIL"
+export PATH=$PWD/../src:$PWD:$PATH
+export LD_LIBRARY_PATH=$LD_LIBRARY_PATH
+. ./functions.sh
+_require evmctl
+
+cleanup() {
+	if [ "$g_loop_mounted" = "1" ]; then
+		popd > /dev/null || exit "$FAIL"
+		umount "$g_mountpoint"
+	fi
+
+	if [ -n "$g_dev" ]; then
+		losetup -d "$g_dev"
+	fi
+
+	if [ -n "$g_image" ]; then
+		rm -f "$g_image"
+	fi
+
+	if [ -n "$g_mountpoint" ]; then
+		rm -Rf "$g_mountpoint"
+	fi
+
+	if [ -n "$key_path_der" ]; then
+		rm -f "$key_path_der"
+	fi
+}
+
+# Use the fsuuid= IMA policy keyword to select only files created/used by the
+# tests below. Also use fowner= to differentiate between files created/used by
+# individual tests.
+IMA_UUID="28b23254-9467-44c0-b6ba-34b12e85a26e"
+MMAP_CHECK_FOWNER=2000
+MMAP_CHECK_REQPROT_FOWNER=2001
+MEASURE_MMAP_CHECK_RULE="measure func=MMAP_CHECK fsuuid=$IMA_UUID fowner=$MMAP_CHECK_FOWNER"
+MEASURE_MMAP_CHECK_REQPROT_RULE="measure func=MMAP_CHECK_REQPROT fsuuid=$IMA_UUID fowner=$MMAP_CHECK_REQPROT_FOWNER"
+APPRAISE_MMAP_CHECK_RULE="appraise func=MMAP_CHECK fsuuid=$IMA_UUID fowner=$MMAP_CHECK_FOWNER"
+APPRAISE_MMAP_CHECK_REQPROT_RULE="appraise func=MMAP_CHECK_REQPROT fsuuid=$IMA_UUID fowner=$MMAP_CHECK_REQPROT_FOWNER"
+
+check_load_ima_rule() {
+	local rule_loaded result new_policy
+
+	rule_loaded=$(grep "$1" /sys/kernel/security/ima/policy)
+	if [ -z "$rule_loaded" ]; then
+		new_policy=$(mktemp -p "$g_mountpoint")
+		echo "$1" > "$new_policy"
+		echo "$new_policy" > /sys/kernel/security/ima/policy
+		result=$?
+		rm -f "$new_policy"
+
+		if [ "$result" -ne 0 ]; then
+			echo "${RED}Failed to set IMA policy${NORM}"
+			return "$HARDFAIL"
+		fi
+	fi
+
+	return "$OK"
+}
+
+check_mmap() {
+	local hook="$1"
+	local arg="$2"
+	local test_file fowner rule result test_file_entry
+
+	echo -e "\nTest: ${FUNCNAME[0]} (hook=\"$hook\", test_mmap arg: \"$arg\")"
+
+	if ! test_file=$(mktemp -p "$PWD"); then
+		echo "${RED}Cannot write $test_file${NORM}"
+		return "$HARDFAIL"
+	fi
+
+	fowner="$MMAP_CHECK_FOWNER"
+	rule="$MEASURE_MMAP_CHECK_RULE"
+
+	if [ "$hook" = "MMAP_CHECK_REQPROT" ]; then
+		fowner="$MMAP_CHECK_REQPROT_FOWNER"
+		rule="$MEASURE_MMAP_CHECK_REQPROT_RULE"
+	fi
+
+	if ! chown "$fowner" "$test_file"; then
+		echo "${RED}Cannot change owner of $test_file${NORM}"
+		return "$HARDFAIL"
+	fi
+
+	check_load_ima_rule "$rule"
+	result=$?
+	if [ $result -ne "$OK" ]; then
+		return $result
+	fi
+
+	test_mmap "$test_file" "$arg"
+
+	if [ "$TFAIL" != "yes" ]; then
+		echo -n "Result (expect found): "
+	else
+		echo -n "Result (expect not found): "
+	fi
+
+	test_file_entry=$(awk '$5 == "'"$test_file"'"' < /sys/kernel/security/ima/ascii_runtime_measurements)
+	if [ -z "$test_file_entry" ]; then
+		echo "not found"
+		return "$FAIL"
+	fi
+
+	echo "found"
+	return "$OK"
+}
+
+check_deny() {
+	local hook="$1"
+	local arg="$2"
+	local test_file fowner rule result
+
+	echo -e "\nTest: ${FUNCNAME[0]} (hook=\"$hook\", test_mmap arg: \"$arg\")"
+
+	if ! test_file=$(mktemp -p "$PWD"); then
+		echo "${RED}Cannot write $test_file${NORM}"
+		return "$HARDFAIL"
+	fi
+
+	echo "test" > "$test_file"
+
+	if ! evmctl ima_sign -a sha256 --key "$key_path" "$test_file" &> /dev/null; then
+		echo "${RED}Cannot sign $test_file${NORM}"
+		return "$HARDFAIL"
+	fi
+
+	fowner="$MMAP_CHECK_FOWNER"
+	rule="$APPRAISE_MMAP_CHECK_RULE"
+
+	if [ "$hook" = "MMAP_CHECK_REQPROT" ]; then
+		fowner="$MMAP_CHECK_REQPROT_FOWNER"
+		rule="$APPRAISE_MMAP_CHECK_REQPROT_RULE"
+	fi
+
+	if ! chown "$fowner" "$test_file"; then
+		echo "${RED}Cannot change owner of $test_file${NORM}"
+		return "$HARDFAIL"
+	fi
+
+	check_load_ima_rule "$rule"
+	result=$?
+	if [ $result -ne "$OK" ]; then
+		return $result
+	fi
+
+	if ! test_mmap "$test_file" exec > /dev/null; then
+		echo "${RED}Cannot read $test_file${NORM}"
+		return "$HARDFAIL"
+	fi
+
+	if [ "$TFAIL" != "yes" ]; then
+		echo -n "Result (expect denied): "
+	else
+		echo -n "Result (expect allowed): "
+	fi
+
+	if test_mmap "$test_file" "$arg"; then
+		echo "allowed"
+		return "$FAIL"
+	fi
+
+	echo "denied"
+	return "$OK"
+}
+
+# Run in the new environment if TST_ENV is set.
+_run_env "$TST_KERNEL" "$PWD/$(basename "$0")" "TST_ENV=$TST_ENV TST_KERNEL=$TST_KERNEL PATH=$PATH LD_LIBRARY_PATH=$LD_LIBRARY_PATH VERBOSE=$VERBOSE"
+
+# Exit from the creator of the new environment.
+_exit_env "$TST_KERNEL"
+
+# Mount filesystems in the new environment.
+_init_env
+
+if [ "$(whoami)" != "root" ]; then
+	echo "${CYAN}This script must be executed as root${NORM}"
+	exit "$SKIP"
+fi
+
+if [ ! -f /sys/kernel/security/ima/policy ]; then
+	echo "${CYAN}IMA policy file not found${NORM}"
+	exit "$SKIP"
+fi
+
+if ! cat /sys/kernel/security/ima/policy &> /dev/null; then
+	echo "${CYAN}IMA policy file is not readable${NORM}"
+	exit "$SKIP"
+fi
+
+if [ -n "$TST_KEY_PATH" ]; then
+	if [ "${TST_KEY_PATH:0:1}" != "/" ]; then
+		echo "${RED}Absolute path required for the signing key${NORM}"
+		exit "$FAIL"
+	fi
+
+	if [ ! -f "$TST_KEY_PATH" ]; then
+		echo "${RED}Kernel signing key not found in $TST_KEY_PATH${NORM}"
+		exit "$FAIL"
+	fi
+
+	key_path="$TST_KEY_PATH"
+elif [ -f "$PWD/../signing_key.pem" ]; then
+	key_path="$PWD/../signing_key.pem"
+elif [ -f "/lib/modules/$(uname -r)/source/certs/signing_key.pem" ]; then
+	key_path="/lib/modules/$(uname -r)/source/certs/signing_key.pem"
+elif [ -f "/lib/modules/$(uname -r)/build/certs/signing_key.pem" ]; then
+	key_path="/lib/modules/$(uname -r)/build/certs/signing_key.pem"
+else
+	echo "${CYAN}Kernel signing key not found${NORM}"
+	exit "$SKIP"
+fi
+
+key_path_der=$(mktemp)
+
+openssl x509 -in "$key_path" -out "$key_path_der" -outform der
+if ! keyctl padd asymmetric pubkey %keyring:.ima < "$key_path_der" &> /dev/null; then
+	echo "${RED}Public key cannot be added to the IMA keyring${NORM}"
+	exit "$FAIL"
+fi
+
+g_mountpoint=$(mktemp -d)
+g_image=$(mktemp)
+
+if [ -z "$g_mountpoint" ]; then
+	echo "${RED}Mountpoint directory not created${NORM}"
+	exit "$FAIL"
+fi
+
+if ! dd if=/dev/zero of="$g_image" bs=1M count=20 &> /dev/null; then
+	echo "${RED}Cannot create test image${NORM}"
+	exit "$FAIL"
+fi
+
+g_dev=$(losetup -f "$g_image" --show)
+if [ -z "$g_dev" ]; then
+	echo "${RED}Cannot create loop device${NORM}"
+	exit "$FAIL"
+fi
+
+if ! mkfs.ext4 -U "$IMA_UUID" -b 4096 "$g_dev" &> /dev/null; then
+	echo "${RED}Cannot format $g_dev${NORM}"
+	exit "$FAIL"
+fi
+
+if ! mount -o i_version "$g_dev" "$g_mountpoint"; then
+	echo "${RED}Cannot mount loop device${NORM}"
+	exit "$FAIL"
+fi
+
+g_loop_mounted=1
+pushd "$g_mountpoint" > /dev/null || exit "$FAIL"
+
+expect_fail check_mmap "MMAP_CHECK" ""
+expect_pass check_mmap "MMAP_CHECK" "exec"
+expect_pass_if '0' check_mmap "MMAP_CHECK" "read_implies_exec"
+
+expect_fail_if '1' check_mmap "MMAP_CHECK_REQPROT" ""
+expect_pass_if '1' check_mmap "MMAP_CHECK_REQPROT" "exec"
+expect_fail_if '1' check_mmap "MMAP_CHECK_REQPROT" "read_implies_exec"
+
+expect_pass check_deny "MMAP_CHECK" "mprotect"
+expect_pass_if '1' check_deny "MMAP_CHECK_REQPROT" "mprotect"
+
+expect_pass check_deny "MMAP_CHECK" "exec_on_writable"
+expect_pass_if '1' check_deny "MMAP_CHECK_REQPROT" "exec_on_writable"
diff --git a/tests/test_mmap.c b/tests/test_mmap.c
new file mode 100644
index 000000000000..6d1beb3bb6a2
--- /dev/null
+++ b/tests/test_mmap.c
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023 Huawei Technologies Duesseldorf GmbH
+ *
+ * Tool to test IMA MMAP_CHECK and MMAP_CHECK_REQPROT hooks.
+ */
+#include <stdio.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <sys/personality.h>
+
+int main(int argc, char *argv[])
+{
+	struct stat st;
+	void *ptr, *ptr_write = NULL;
+	int ret, fd, fd_write, prot = PROT_READ;
+
+	if (!argv[1])
+		return -ENOENT;
+
+	if (argv[2] && !strcmp(argv[2], "read_implies_exec")) {
+		ret = personality(READ_IMPLIES_EXEC);
+		if (ret < 0)
+			return ret;
+	}
+
+	if (stat(argv[1], &st) == -1)
+		return -errno;
+
+	if (argv[2] && !strcmp(argv[2], "exec_on_writable")) {
+		fd_write = open(argv[1], O_RDWR);
+		if (fd_write == -1)
+			return -errno;
+
+		ptr_write = mmap(0, st.st_size, PROT_WRITE, MAP_SHARED,
+				 fd_write, 0);
+		close(fd_write);
+
+		if (ptr_write == (void *)-1)
+			return -errno;
+	}
+
+	fd = open(argv[1], O_RDONLY);
+	if (fd == -1) {
+		if (ptr_write)
+			munmap(ptr_write, st.st_size);
+
+		return -errno;
+	}
+
+	if (argv[2] && !strncmp(argv[2], "exec", 4))
+		prot |= PROT_EXEC;
+
+	ptr = mmap(0, st.st_size, prot, MAP_PRIVATE, fd, 0);
+
+	close(fd);
+
+	if (ptr_write)
+		munmap(ptr_write, st.st_size);
+
+	if (ptr == (void *)-1)
+		return -errno;
+
+	ret = 0;
+
+	if (argv[2] && !strcmp(argv[2], "mprotect"))
+		ret = mprotect(ptr, st.st_size, PROT_EXEC);
+
+	munmap(ptr, st.st_size);
+	return ret;
+}
-- 
2.25.1

Re: [PATCH ima-evm-utils v2] Add tests for MMAP_CHECK and MMAP_CHECK_REQPROT hooks

[Stefan Berger]

On 1/31/23 12:42, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@huawei.com>
> 


> +check_mmap() {
> +	local hook="$1"
> +	local arg="$2"
> +	local test_file fowner rule result test_file_entry
> +
> +	echo -e "\nTest: ${FUNCNAME[0]} (hook=\"$hook\", test_mmap arg: \"$arg\")"
> +
> +	if ! test_file=$(mktemp -p "$PWD"); then
> +		echo "${RED}Cannot write $test_file${NORM}"
> +		return "$HARDFAIL"
> +	fi
> +
> +	fowner="$MMAP_CHECK_FOWNER"
> +	rule="$MEASURE_MMAP_CHECK_RULE"
> +
> +	if [ "$hook" = "MMAP_CHECK_REQPROT" ]; then
> +		fowner="$MMAP_CHECK_REQPROT_FOWNER"
> +		rule="$MEASURE_MMAP_CHECK_REQPROT_RULE"
> +	fi
> +
> +	if ! chown "$fowner" "$test_file"; then
> +		echo "${RED}Cannot change owner of $test_file${NORM}"
> +		return "$HARDFAIL"
> +	fi
> +
> +	check_load_ima_rule "$rule"
> +	result=$?
> +	if [ $result -ne "$OK" ]; then
> +		return $result
> +	fi
> +
> +	test_mmap "$test_file" "$arg"

In this case it should succeed or fail depending on the $rule?  I am just wondering whether to check $? here as well for expected outcome...

> +
> +	if [ "$TFAIL" != "yes" ]; then
> +		echo -n "Result (expect found): "
> +	else
> +		echo -n "Result (expect not found): "
> +	fi
> +
> +	test_file_entry=$(awk '$5 == "'"$test_file"'"' < /sys/kernel/security/ima/ascii_runtime_measurements)
> +	if [ -z "$test_file_entry" ]; then
> +		echo "not found"
> +		return "$FAIL"
> +	fi
> +
> +	echo "found"
> +	return "$OK"
> +}

> +if [ -n "$TST_KEY_PATH" ]; then
> +	if [ "${TST_KEY_PATH:0:1}" != "/" ]; then
> +		echo "${RED}Absolute path required for the signing key${NORM}"
> +		exit "$FAIL"
> +	fi
> +
> +	if [ ! -f "$TST_KEY_PATH" ]; then
> +		echo "${RED}Kernel signing key not found in $TST_KEY_PATH${NORM}"
> +		exit "$FAIL"
> +	fi
> +
> +	key_path="$TST_KEY_PATH"

g_key_path ? or pass as parameter to check_deny (better IMO)

> +elif [ -f "$PWD/../signing_key.pem" ]; then
> +	key_path="$PWD/../signing_key.pem"
> +elif [ -f "/lib/modules/$(uname -r)/source/certs/signing_key.pem" ]; then
> +	key_path="/lib/modules/$(uname -r)/source/certs/signing_key.pem"
> +elif [ -f "/lib/modules/$(uname -r)/build/certs/signing_key.pem" ]; then
> +	key_path="/lib/modules/$(uname -r)/build/certs/signing_key.pem"
> +else
> +	echo "${CYAN}Kernel signing key not found${NORM}"
> +	exit "$SKIP"
> +fi
> +
> +key_path_der=$(mktemp)

g_key_path_der for consistency

> +++ b/tests/test_mmap.c
> @@ -0,0 +1,75 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2023 Huawei Technologies Duesseldorf GmbH
> + *
> + * Tool to test IMA MMAP_CHECK and MMAP_CHECK_REQPROT hooks.
> + */
> +#include <stdio.h>
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <sys/stat.h>
> +#include <sys/mman.h>
> +#include <sys/personality.h>
> +
> +int main(int argc, char *argv[])
> +{
> +	struct stat st;
> +	void *ptr, *ptr_write = NULL;
> +	int ret, fd, fd_write, prot = PROT_READ;
> +
> +	if (!argv[1])
> +		return -ENOENT;
> +
> +	if (argv[2] && !strcmp(argv[2], "read_implies_exec")) {
> +		ret = personality(READ_IMPLIES_EXEC);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	if (stat(argv[1], &st) == -1)
> +		return -errno;
> +
> +	if (argv[2] && !strcmp(argv[2], "exec_on_writable")) {
> +		fd_write = open(argv[1], O_RDWR);
> +		if (fd_write == -1)
> +			return -errno;
> +
> +		ptr_write = mmap(0, st.st_size, PROT_WRITE, MAP_SHARED,
> +				 fd_write, 0);
> +		close(fd_write);
> +
> +		if (ptr_write == (void *)-1)
> +			return -errno;
> +	}
> +
> +	fd = open(argv[1], O_RDONLY);
> +	if (fd == -1) {
> +		if (ptr_write)
> +			munmap(ptr_write, st.st_size);
> +
> +		return -errno;
> +	}
> +
> +	if (argv[2] && !strncmp(argv[2], "exec", 4))
> +		prot |= PROT_EXEC;
> +
> +	ptr = mmap(0, st.st_size, prot, MAP_PRIVATE, fd, 0);
> +
> +	close(fd);
> +
> +	if (ptr_write)
> +		munmap(ptr_write, st.st_size);
> +
> +	if (ptr == (void *)-1)
> +		return -errno;
> +
> +	ret = 0;
> +
> +	if (argv[2] && !strcmp(argv[2], "mprotect"))
> +		ret = mprotect(ptr, st.st_size, PROT_EXEC);
> +
> +	munmap(ptr, st.st_size);
> +	return ret;
> +}

Are there any unexpected failure cases here where it should report an error to the user?

    Stefan

Re: [PATCH ima-evm-utils v2] Add tests for MMAP_CHECK and MMAP_CHECK_REQPROT hooks

[Mimi Zohar]

On Tue, 2023-01-31 at 18:42 +0100, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@huawei.com>
> 
> Add tests to ensure that, after applying the kernel patch 'ima: Align
> ima_file_mmap() parameters with mmap_file LSM hook', the MMAP_CHECK hook
> checks the protections applied by the kernel and not those requested by the
> application.
> 
> Also ensure that after applying 'ima: Introduce MMAP_CHECK_REQPROT hook',
> the MMAP_CHECK_REQPROT hook checks the protections requested by the
> application.
> 
> Test both with the test_mmap application that by default requests the
> PROT_READ protection flag. Its syntax is:
> 
> test_mmap <file> <mode>
> 
> where mode can be:
> - exec: adds the PROT_EXEC protection flag to mmap()
> - read_implies_exec: calls the personality() system call with
>                      READ_IMPLIES_EXEC as the first argument before mmap()
> - mprotect: adds the PROT_EXEC protection flag to a memory area in addition
>             to PROT_READ
> - exec_on_writable: calls mmap() with PROT_EXEC on a file which has a
>                     writable mapping
> 
> Check the different combinations of hooks/modes and ensure that a
> measurement entry is found in the IMA measurement list only when it is
> expected. No measurement entry should be found when only the PROT_READ
> protection flag is requested or the matching policy rule has the
> MMAP_CHECK_REQPROT hook and the personality() system call was called with
> READ_IMPLIES_EXEC.
> 
> mprotect() with PROT_EXEC on an existing memory area protected with
> PROT_READ should be denied (with an appraisal rule), regardless of the MMAP
> hook specified in the policy. The same applies for mmap() with PROT_EXEC on
> a file with a writable mapping.
> 
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>

Nice!   Including some comments, or at least the test assumption, would
help simplify reviewing the code.

Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>

Re: [PATCH ima-evm-utils v2] Add tests for MMAP_CHECK and MMAP_CHECK_REQPROT hooks

[Mimi Zohar]

Hi Roberto,

> +check_mmap() {
> +	local hook="$1"
> +	local arg="$2"
> +	local test_file fowner rule result test_file_entry
> +
> +	echo -e "\nTest: ${FUNCNAME[0]} (hook=\"$hook\", test_mmap arg: \"$arg\")"
> +
> +	if ! test_file=$(mktemp -p "$PWD"); then
> +		echo "${RED}Cannot write $test_file${NORM}"
> +		return "$HARDFAIL"
> +	fi
> +
> +	fowner="$MMAP_CHECK_FOWNER"
> +	rule="$MEASURE_MMAP_CHECK_RULE"
> +
> +	if [ "$hook" = "MMAP_CHECK_REQPROT" ]; then
> +		fowner="$MMAP_CHECK_REQPROT_FOWNER"
> +		rule="$MEASURE_MMAP_CHECK_REQPROT_RULE"
> +	fi
> +
> +	if ! chown "$fowner" "$test_file"; then
> +		echo "${RED}Cannot change owner of $test_file${NORM}"
> +		return "$HARDFAIL"
> +	fi
> +
> +	check_load_ima_rule "$rule"
> +	result=$?
> +	if [ $result -ne "$OK" ]; then
> +		return $result
> +	fi
> +
> +	test_mmap "$test_file" "$arg"
> +
> +	if [ "$TFAIL" != "yes" ]; then
> +		echo -n "Result (expect found): "
> +	else
> +		echo -n "Result (expect not found): "
> +	fi
> +
> +	test_file_entry=$(awk '$5 == "'"$test_file"'"' < /sys/kernel/security/ima/ascii_runtime_measurements)
> +	if [ -z "$test_file_entry" ]; then
> +		echo "not found"
> +		return "$FAIL"
> +	fi

Using temporary files should prevent having multiple records.  Having a
verbose option to show the actual matching measurement list record
would be nice.

> +
> +	echo "found"
> +	return "$OK"
> +}
> +



> +
> +# Run in the new environment if TST_ENV is set.
> +_run_env "$TST_KERNEL" "$PWD/$(basename "$0")" "TST_ENV=$TST_ENV TST_KERNEL=$TST_KERNEL PATH=$PATH LD_LIBRARY_PATH=$LD_LIBRARY_PATH VERBOSE=$VERBOSE"
> +
> +# Exit from the creator of the new environment.
> +_exit_env "$TST_KERNEL"
> +
> +# Mount filesystems in the new environment.
> +_init_env
> +
> +if [ "$(whoami)" != "root" ]; then
> +	echo "${CYAN}This script must be executed as root${NORM}"
> +	exit "$SKIP"
> +fi
> +
> +if [ ! -f /sys/kernel/security/ima/policy ]; then
> +	echo "${CYAN}IMA policy file not found${NORM}"
> +	exit "$SKIP"
> +fi
> +
> +if ! cat /sys/kernel/security/ima/policy &> /dev/null; then
> +	echo "${CYAN}IMA policy file is not readable${NORM}"
> +	exit "$SKIP"
> +fi

An existing policy with an mmap rule would affect this test.  Check to
see if one already exists.

> +
> +if [ -n "$TST_KEY_PATH" ]; then
> +	if [ "${TST_KEY_PATH:0:1}" != "/" ]; then
> +		echo "${RED}Absolute path required for the signing key${NORM}"
> +		exit "$FAIL"
> +	fi
> 

-- 
thanks,

Mimi

Re: [PATCH ima-evm-utils v2] Add tests for MMAP_CHECK and MMAP_CHECK_REQPROT hooks

[Mimi Zohar]

On Tue, 2023-01-31 at 19:00 -0500, Mimi Zohar wrote:
> On Tue, 2023-01-31 at 18:42 +0100, Roberto Sassu wrote:
> > From: Roberto Sassu <roberto.sassu@huawei.com>
> > 
> > Add tests to ensure that, after applying the kernel patch 'ima: Align
> > ima_file_mmap() parameters with mmap_file LSM hook', the MMAP_CHECK hook
> > checks the protections applied by the kernel and not those requested by the
> > application.
> > 
> > Also ensure that after applying 'ima: Introduce MMAP_CHECK_REQPROT hook',
> > the MMAP_CHECK_REQPROT hook checks the protections requested by the
> > application.
> > 
> > Test both with the test_mmap application that by default requests the
> > PROT_READ protection flag. Its syntax is:
> > 
> > test_mmap <file> <mode>
> > 
> > where mode can be:
> > - exec: adds the PROT_EXEC protection flag to mmap()
> > - read_implies_exec: calls the personality() system call with
> >                      READ_IMPLIES_EXEC as the first argument before mmap()
> > - mprotect: adds the PROT_EXEC protection flag to a memory area in addition
> >             to PROT_READ
> > - exec_on_writable: calls mmap() with PROT_EXEC on a file which has a
> >                     writable mapping
> > 
> > Check the different combinations of hooks/modes and ensure that a
> > measurement entry is found in the IMA measurement list only when it is
> > expected. No measurement entry should be found when only the PROT_READ
> > protection flag is requested or the matching policy rule has the
> > MMAP_CHECK_REQPROT hook and the personality() system call was called with
> > READ_IMPLIES_EXEC.
> > 
> > mprotect() with PROT_EXEC on an existing memory area protected with
> > PROT_READ should be denied (with an appraisal rule), regardless of the MMAP
> > hook specified in the policy. The same applies for mmap() with PROT_EXEC on
> > a file with a writable mapping.
> > 
> > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> 
> Nice!   Including some comments, or at least the test assumption, would
> help simplify reviewing the code.

An example of a test assumption, or background information, for the
"mprotect" test is described in the ima_file_mprotect() function
comment:

 * Files can be mmap'ed read/write and later changed to execute to circumvent
 * IMA's mmap appraisal policy rules.  Due to locking issues (mmap semaphore
 * would be taken before i_mutex), files can not be measured or appraised at
 * this point.  Eliminate this integrity gap by denying the mprotect
 * PROT_EXECUTE change, if an mmap appraise policy rule exists.

-- 
thanks,

Mimi

Re: [PATCH ima-evm-utils v2] Add tests for MMAP_CHECK and MMAP_CHECK_REQPROT hooks

[Roberto Sassu]

On Tue, 2023-01-31 at 17:39 -0500, Stefan Berger wrote:
> 
> On 1/31/23 12:42, Roberto Sassu wrote:
> > From: Roberto Sassu <roberto.sassu@huawei.com>
> > 
> > +check_mmap() {
> > +	local hook="$1"
> > +	local arg="$2"
> > +	local test_file fowner rule result test_file_entry
> > +
> > +	echo -e "\nTest: ${FUNCNAME[0]} (hook=\"$hook\", test_mmap arg: \"$arg\")"
> > +
> > +	if ! test_file=$(mktemp -p "$PWD"); then
> > +		echo "${RED}Cannot write $test_file${NORM}"
> > +		return "$HARDFAIL"
> > +	fi
> > +
> > +	fowner="$MMAP_CHECK_FOWNER"
> > +	rule="$MEASURE_MMAP_CHECK_RULE"
> > +
> > +	if [ "$hook" = "MMAP_CHECK_REQPROT" ]; then
> > +		fowner="$MMAP_CHECK_REQPROT_FOWNER"
> > +		rule="$MEASURE_MMAP_CHECK_REQPROT_RULE"
> > +	fi
> > +
> > +	if ! chown "$fowner" "$test_file"; then
> > +		echo "${RED}Cannot change owner of $test_file${NORM}"
> > +		return "$HARDFAIL"
> > +	fi
> > +
> > +	check_load_ima_rule "$rule"
> > +	result=$?
> > +	if [ $result -ne "$OK" ]; then
> > +		return $result
> > +	fi
> > +
> > +	test_mmap "$test_file" "$arg"
> 
> In this case it should succeed or fail depending on the $rule?  I am just wondering whether to check $? here as well for expected outcome...

I agree. For the check_mmap() test, test_mmap is always expected to
succeed.

> > +
> > +	if [ "$TFAIL" != "yes" ]; then
> > +		echo -n "Result (expect found): "
> > +	else
> > +		echo -n "Result (expect not found): "
> > +	fi
> > +
> > +	test_file_entry=$(awk '$5 == "'"$test_file"'"' < /sys/kernel/security/ima/ascii_runtime_measurements)
> > +	if [ -z "$test_file_entry" ]; then
> > +		echo "not found"
> > +		return "$FAIL"
> > +	fi
> > +
> > +	echo "found"
> > +	return "$OK"
> > +}
> > +if [ -n "$TST_KEY_PATH" ]; then
> > +	if [ "${TST_KEY_PATH:0:1}" != "/" ]; then
> > +		echo "${RED}Absolute path required for the signing key${NORM}"
> > +		exit "$FAIL"
> > +	fi
> > +
> > +	if [ ! -f "$TST_KEY_PATH" ]; then
> > +		echo "${RED}Kernel signing key not found in $TST_KEY_PATH${NORM}"
> > +		exit "$FAIL"
> > +	fi
> > +
> > +	key_path="$TST_KEY_PATH"
> 
> g_key_path ? or pass as parameter to check_deny (better IMO)

There are other global variables. Also the expect_ lines now are clean
and say more or less what the test is about. Maybe better g_key_path,
will think about for new tests.

> > +elif [ -f "$PWD/../signing_key.pem" ]; then
> > +	key_path="$PWD/../signing_key.pem"
> > +elif [ -f "/lib/modules/$(uname -r)/source/certs/signing_key.pem" ]; then
> > +	key_path="/lib/modules/$(uname -r)/source/certs/signing_key.pem"
> > +elif [ -f "/lib/modules/$(uname -r)/build/certs/signing_key.pem" ]; then
> > +	key_path="/lib/modules/$(uname -r)/build/certs/signing_key.pem"
> > +else
> > +	echo "${CYAN}Kernel signing key not found${NORM}"
> > +	exit "$SKIP"
> > +fi
> > +
> > +key_path_der=$(mktemp)
> 
> g_key_path_der for consistency

Ok.

> > +++ b/tests/test_mmap.c
> > @@ -0,0 +1,75 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (C) 2023 Huawei Technologies Duesseldorf GmbH
> > + *
> > + * Tool to test IMA MMAP_CHECK and MMAP_CHECK_REQPROT hooks.
> > + */
> > +#include <stdio.h>
> > +#include <errno.h>
> > +#include <fcntl.h>
> > +#include <string.h>
> > +#include <unistd.h>
> > +#include <sys/stat.h>
> > +#include <sys/mman.h>
> > +#include <sys/personality.h>
> > +
> > +int main(int argc, char *argv[])
> > +{
> > +	struct stat st;
> > +	void *ptr, *ptr_write = NULL;
> > +	int ret, fd, fd_write, prot = PROT_READ;
> > +
> > +	if (!argv[1])
> > +		return -ENOENT;
> > +
> > +	if (argv[2] && !strcmp(argv[2], "read_implies_exec")) {
> > +		ret = personality(READ_IMPLIES_EXEC);
> > +		if (ret < 0)
> > +			return ret;
> > +	}
> > +
> > +	if (stat(argv[1], &st) == -1)
> > +		return -errno;
> > +
> > +	if (argv[2] && !strcmp(argv[2], "exec_on_writable")) {
> > +		fd_write = open(argv[1], O_RDWR);
> > +		if (fd_write == -1)
> > +			return -errno;
> > +
> > +		ptr_write = mmap(0, st.st_size, PROT_WRITE, MAP_SHARED,
> > +				 fd_write, 0);
> > +		close(fd_write);
> > +
> > +		if (ptr_write == (void *)-1)
> > +			return -errno;
> > +	}
> > +
> > +	fd = open(argv[1], O_RDONLY);
> > +	if (fd == -1) {
> > +		if (ptr_write)
> > +			munmap(ptr_write, st.st_size);
> > +
> > +		return -errno;
> > +	}
> > +
> > +	if (argv[2] && !strncmp(argv[2], "exec", 4))
> > +		prot |= PROT_EXEC;
> > +
> > +	ptr = mmap(0, st.st_size, prot, MAP_PRIVATE, fd, 0);
> > +
> > +	close(fd);
> > +
> > +	if (ptr_write)
> > +		munmap(ptr_write, st.st_size);
> > +
> > +	if (ptr == (void *)-1)
> > +		return -errno;
> > +
> > +	ret = 0;
> > +
> > +	if (argv[2] && !strcmp(argv[2], "mprotect"))
> > +		ret = mprotect(ptr, st.st_size, PROT_EXEC);
> > +
> > +	munmap(ptr, st.st_size);
> > +	return ret;
> > +}
> 
> Are there any unexpected failure cases here where it should report an error to the user?

Uhm, ok. I differentiated when an error could occur from when it should
not.

Roberto

Re: [PATCH ima-evm-utils v2] Add tests for MMAP_CHECK and MMAP_CHECK_REQPROT hooks

[Roberto Sassu]

On Wed, 2023-02-01 at 08:48 -0500, Mimi Zohar wrote:
> On Tue, 2023-01-31 at 19:00 -0500, Mimi Zohar wrote:
> > On Tue, 2023-01-31 at 18:42 +0100, Roberto Sassu wrote:
> > > From: Roberto Sassu <roberto.sassu@huawei.com>
> > > 
> > > Add tests to ensure that, after applying the kernel patch 'ima: Align
> > > ima_file_mmap() parameters with mmap_file LSM hook', the MMAP_CHECK hook
> > > checks the protections applied by the kernel and not those requested by the
> > > application.
> > > 
> > > Also ensure that after applying 'ima: Introduce MMAP_CHECK_REQPROT hook',
> > > the MMAP_CHECK_REQPROT hook checks the protections requested by the
> > > application.
> > > 
> > > Test both with the test_mmap application that by default requests the
> > > PROT_READ protection flag. Its syntax is:
> > > 
> > > test_mmap <file> <mode>
> > > 
> > > where mode can be:
> > > - exec: adds the PROT_EXEC protection flag to mmap()
> > > - read_implies_exec: calls the personality() system call with
> > >                      READ_IMPLIES_EXEC as the first argument before mmap()
> > > - mprotect: adds the PROT_EXEC protection flag to a memory area in addition
> > >             to PROT_READ
> > > - exec_on_writable: calls mmap() with PROT_EXEC on a file which has a
> > >                     writable mapping
> > > 
> > > Check the different combinations of hooks/modes and ensure that a
> > > measurement entry is found in the IMA measurement list only when it is
> > > expected. No measurement entry should be found when only the PROT_READ
> > > protection flag is requested or the matching policy rule has the
> > > MMAP_CHECK_REQPROT hook and the personality() system call was called with
> > > READ_IMPLIES_EXEC.
> > > 
> > > mprotect() with PROT_EXEC on an existing memory area protected with
> > > PROT_READ should be denied (with an appraisal rule), regardless of the MMAP
> > > hook specified in the policy. The same applies for mmap() with PROT_EXEC on
> > > a file with a writable mapping.
> > > 
> > > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> > 
> > Nice!   Including some comments, or at least the test assumption, would
> > help simplify reviewing the code.
> 
> An example of a test assumption, or background information, for the
> "mprotect" test is described in the ima_file_mprotect() function
> comment:
> 
>  * Files can be mmap'ed read/write and later changed to execute to circumvent
>  * IMA's mmap appraisal policy rules.  Due to locking issues (mmap semaphore
>  * would be taken before i_mutex), files can not be measured or appraised at
>  * this point.  Eliminate this integrity gap by denying the mprotect
>  * PROT_EXECUTE change, if an mmap appraise policy rule exists.

Ok, I added the description to each test. Will send the new patch
shortly.

Roberto

Re: [PATCH ima-evm-utils v2] Add tests for MMAP_CHECK and MMAP_CHECK_REQPROT hooks

[Roberto Sassu]

On Tue, 2023-01-31 at 22:02 -0500, Mimi Zohar wrote:
> Hi Roberto,
> 
> > +check_mmap() {
> > +	local hook="$1"
> > +	local arg="$2"
> > +	local test_file fowner rule result test_file_entry
> > +
> > +	echo -e "\nTest: ${FUNCNAME[0]} (hook=\"$hook\", test_mmap arg: \"$arg\")"
> > +
> > +	if ! test_file=$(mktemp -p "$PWD"); then
> > +		echo "${RED}Cannot write $test_file${NORM}"
> > +		return "$HARDFAIL"
> > +	fi
> > +
> > +	fowner="$MMAP_CHECK_FOWNER"
> > +	rule="$MEASURE_MMAP_CHECK_RULE"
> > +
> > +	if [ "$hook" = "MMAP_CHECK_REQPROT" ]; then
> > +		fowner="$MMAP_CHECK_REQPROT_FOWNER"
> > +		rule="$MEASURE_MMAP_CHECK_REQPROT_RULE"
> > +	fi
> > +
> > +	if ! chown "$fowner" "$test_file"; then
> > +		echo "${RED}Cannot change owner of $test_file${NORM}"
> > +		return "$HARDFAIL"
> > +	fi
> > +
> > +	check_load_ima_rule "$rule"
> > +	result=$?
> > +	if [ $result -ne "$OK" ]; then
> > +		return $result
> > +	fi
> > +
> > +	test_mmap "$test_file" "$arg"
> > +
> > +	if [ "$TFAIL" != "yes" ]; then
> > +		echo -n "Result (expect found): "
> > +	else
> > +		echo -n "Result (expect not found): "
> > +	fi
> > +
> > +	test_file_entry=$(awk '$5 == "'"$test_file"'"' < /sys/kernel/security/ima/ascii_runtime_measurements)
> > +	if [ -z "$test_file_entry" ]; then
> > +		echo "not found"
> > +		return "$FAIL"
> > +	fi
> 
> Using temporary files should prevent having multiple records.  Having a
> verbose option to show the actual matching measurement list record
> would be nice.
> 
> > +
> > +	echo "found"
> > +	return "$OK"
> > +}
> > +
> 
> 
> > +
> > +# Run in the new environment if TST_ENV is set.
> > +_run_env "$TST_KERNEL" "$PWD/$(basename "$0")" "TST_ENV=$TST_ENV TST_KERNEL=$TST_KERNEL PATH=$PATH LD_LIBRARY_PATH=$LD_LIBRARY_PATH VERBOSE=$VERBOSE"
> > +
> > +# Exit from the creator of the new environment.
> > +_exit_env "$TST_KERNEL"
> > +
> > +# Mount filesystems in the new environment.
> > +_init_env
> > +
> > +if [ "$(whoami)" != "root" ]; then
> > +	echo "${CYAN}This script must be executed as root${NORM}"
> > +	exit "$SKIP"
> > +fi
> > +
> > +if [ ! -f /sys/kernel/security/ima/policy ]; then
> > +	echo "${CYAN}IMA policy file not found${NORM}"
> > +	exit "$SKIP"
> > +fi
> > +
> > +if ! cat /sys/kernel/security/ima/policy &> /dev/null; then
> > +	echo "${CYAN}IMA policy file is not readable${NORM}"
> > +	exit "$SKIP"
> > +fi
> 
> An existing policy with an mmap rule would affect this test.  Check to
> see if one already exists.

Not sure about this. We are specifying the filesystem UUID and the file
owner. Should be enough to avoid interferences. Also
check_load_ima_rule() avoids duplicated rules.

Roberto

> > +
> > +if [ -n "$TST_KEY_PATH" ]; then
> > +	if [ "${TST_KEY_PATH:0:1}" != "/" ]; then
> > +		echo "${RED}Absolute path required for the signing key${NORM}"
> > +		exit "$FAIL"
> > +	fi
> > 

Re: [PATCH ima-evm-utils v2] Add tests for MMAP_CHECK and MMAP_CHECK_REQPROT hooks

[Mimi Zohar]

On Wed, 2023-02-01 at 18:29 +0100, Roberto Sassu wrote:
> On Tue, 2023-01-31 at 22:02 -0500, Mimi Zohar wrote:
> > Hi Roberto,
> > 
> > > +check_mmap() {
> > > +	local hook="$1"
> > > +	local arg="$2"
> > > +	local test_file fowner rule result test_file_entry
> > > +
> > > +	echo -e "\nTest: ${FUNCNAME[0]} (hook=\"$hook\", test_mmap arg: \"$arg\")"
> > > +
> > > +	if ! test_file=$(mktemp -p "$PWD"); then
> > > +		echo "${RED}Cannot write $test_file${NORM}"
> > > +		return "$HARDFAIL"
> > > +	fi
> > > +
> > > +	fowner="$MMAP_CHECK_FOWNER"
> > > +	rule="$MEASURE_MMAP_CHECK_RULE"
> > > +
> > > +	if [ "$hook" = "MMAP_CHECK_REQPROT" ]; then
> > > +		fowner="$MMAP_CHECK_REQPROT_FOWNER"
> > > +		rule="$MEASURE_MMAP_CHECK_REQPROT_RULE"
> > > +	fi
> > > +
> > > +	if ! chown "$fowner" "$test_file"; then
> > > +		echo "${RED}Cannot change owner of $test_file${NORM}"
> > > +		return "$HARDFAIL"
> > > +	fi
> > > +
> > > +	check_load_ima_rule "$rule"
> > > +	result=$?
> > > +	if [ $result -ne "$OK" ]; then
> > > +		return $result
> > > +	fi
> > > +
> > > +	test_mmap "$test_file" "$arg"
> > > +
> > > +	if [ "$TFAIL" != "yes" ]; then
> > > +		echo -n "Result (expect found): "
> > > +	else
> > > +		echo -n "Result (expect not found): "
> > > +	fi
> > > +
> > > +	test_file_entry=$(awk '$5 == "'"$test_file"'"' < /sys/kernel/security/ima/ascii_runtime_measurements)
> > > +	if [ -z "$test_file_entry" ]; then
> > > +		echo "not found"
> > > +		return "$FAIL"
> > > +	fi
> > 
> > Using temporary files should prevent having multiple records.  Having a
> > verbose option to show the actual matching measurement list record
> > would be nice.
> > 
> > > +
> > > +	echo "found"
> > > +	return "$OK"
> > > +}
> > > +
> > 
> > 
> > > +
> > > +# Run in the new environment if TST_ENV is set.
> > > +_run_env "$TST_KERNEL" "$PWD/$(basename "$0")" "TST_ENV=$TST_ENV TST_KERNEL=$TST_KERNEL PATH=$PATH LD_LIBRARY_PATH=$LD_LIBRARY_PATH VERBOSE=$VERBOSE"
> > > +
> > > +# Exit from the creator of the new environment.
> > > +_exit_env "$TST_KERNEL"
> > > +
> > > +# Mount filesystems in the new environment.
> > > +_init_env
> > > +
> > > +if [ "$(whoami)" != "root" ]; then
> > > +	echo "${CYAN}This script must be executed as root${NORM}"
> > > +	exit "$SKIP"
> > > +fi
> > > +
> > > +if [ ! -f /sys/kernel/security/ima/policy ]; then
> > > +	echo "${CYAN}IMA policy file not found${NORM}"
> > > +	exit "$SKIP"
> > > +fi
> > > +
> > > +if ! cat /sys/kernel/security/ima/policy &> /dev/null; then
> > > +	echo "${CYAN}IMA policy file is not readable${NORM}"
> > > +	exit "$SKIP"
> > > +fi
> > 
> > An existing policy with an mmap rule would affect this test.  Check to
> > see if one already exists.
> 
> Not sure about this. We are specifying the filesystem UUID and the file
> owner. Should be enough to avoid interferences. Also
> check_load_ima_rule() avoids duplicated rules.

Since the policy rules are walked sequentially, existing mmap rules
without the uuid or owner qualifiers will interfere with the test
policy rules.   To see the problem load a custom policy containing an
mmap rule, without any qualifiers.  Then run the mmap_check test.

> 
> > > +
> > > +if [ -n "$TST_KEY_PATH" ]; then
> > > +	if [ "${TST_KEY_PATH:0:1}" != "/" ]; then
> > > +		echo "${RED}Absolute path required for the signing key${NORM}"
> > > +		exit "$FAIL"
> > > +	fi
> > > 
>