linux-kernel - [PATCH v8 8/8] ima: add FIRMWARE_PARTIAL

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Date:   Tue,  9 Jun 2020 15:56:56 -0700
From:   Scott Branden <scott.branden@...adcom.com>
To:     Luis Chamberlain <mcgrof@...nel.org>,
        Wolfram Sang <wsa@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        David Brown <david.brown@...aro.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Shuah Khan <shuah@...nel.org>, bjorn.andersson@...aro.org,
        Shuah Khan <skhan@...uxfoundation.org>,
        Arnd Bergmann <arnd@...db.de>
Cc:     Mimi Zohar <zohar@...ux.ibm.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-fsdevel@...r.kernel.org,
        BCM Kernel Feedback <bcm-kernel-feedback-list@...adcom.com>,
        Olof Johansson <olof@...om.net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Colin Ian King <colin.king@...onical.com>,
        Kees Cook <keescook@...omium.org>,
        Takashi Iwai <tiwai@...e.de>, linux-kselftest@...r.kernel.org,
        Andy Gross <agross@...nel.org>,
        linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        Scott Branden <scott.branden@...adcom.com>
Subject: [PATCH v8 8/8] ima: add FIRMWARE_PARTIAL_READ support

Add FIRMWARE_PARTIAL_READ support for integrity
measurement on partial reads of firmware files.

Signed-off-by: Scott Branden <scott.branden@...adcom.com>
---
 security/integrity/ima/ima_main.c | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 800fb3bba418..fc5134807acf 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -609,6 +609,9 @@ void ima_post_path_mknod(struct dentry *dentry)
  */
 int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
 {
+	enum ima_hooks func;
+	u32 secid;
+
 	/*
 	 * READING_FIRMWARE_PREALLOC_BUFFER
 	 *
@@ -617,11 +620,27 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
 	 * of IMA's signature verification any more than when using two
 	 * buffers?
 	 */
-	return 0;
+	if (read_id != READING_FIRMWARE_PARTIAL_READ)
+		return 0;
+
+	if (!file) {
+		if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
+		    (ima_appraise & IMA_APPRAISE_ENFORCE)) {
+			pr_err("Prevent firmware loading_store.\n");
+			return -EACCES;	/* INTEGRITY_UNKNOWN */
+		}
+		return 0;
+	}
+
+	func = read_idmap[read_id] ?: FILE_CHECK;
+	security_task_getsecid(current, &secid);
+	return process_measurement(file, current_cred(), secid, NULL,
+				   0, MAY_READ, func);
 }
 
 const int read_idmap[READING_MAX_ID] = {
 	[READING_FIRMWARE] = FIRMWARE_CHECK,
+	[READING_FIRMWARE_PARTIAL_READ] = FIRMWARE_CHECK,
 	[READING_FIRMWARE_PREALLOC_BUFFER] = FIRMWARE_CHECK,
 	[READING_MODULE] = MODULE_CHECK,
 	[READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK,
@@ -648,6 +667,9 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
 	enum ima_hooks func;
 	u32 secid;
 
+	if (read_id == READING_FIRMWARE_PARTIAL_READ)
+		return 0;
+
 	if (!file && read_id == READING_FIRMWARE) {
 		if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
 		    (ima_appraise & IMA_APPRAISE_ENFORCE)) {
-- 
2.17.1