linux-kernel - [PATCH v11 7/9] ima: verify if the segment size has changed

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Message-ID: <20250402124725.5601-8-chenste@linux.microsoft.com>
Date: Wed,  2 Apr 2025 05:47:20 -0700
From: steven chen <chenste@...ux.microsoft.com>
To: zohar@...ux.ibm.com,
	stefanb@...ux.ibm.com,
	roberto.sassu@...weicloud.com,
	roberto.sassu@...wei.com,
	eric.snowberg@...cle.com,
	ebiederm@...ssion.com,
	paul@...l-moore.com,
	code@...icks.com,
	bauermann@...abnow.com,
	linux-integrity@...r.kernel.org,
	kexec@...ts.infradead.org,
	linux-security-module@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: madvenka@...ux.microsoft.com,
	nramas@...ux.microsoft.com,
	James.Bottomley@...senPartnership.com,
	bhe@...hat.com,
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Subject: [PATCH v11 7/9] ima: verify if the segment size has changed

kexec 'load' may be called multiple times. Free and realloc the buffer
only if the segment_size is changed from the previous kexec 'load' call.

Signed-off-by: steven chen <chenste@...ux.microsoft.com>
---
 security/integrity/ima/ima_kexec.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index 5c3b3e0b2186..ed867734ee70 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -33,6 +33,14 @@ static void ima_free_kexec_file_buf(struct seq_file *sf)
 
 static int ima_alloc_kexec_file_buf(size_t segment_size)
 {
+	/*
+	 * kexec 'load' may be called multiple times.
+	 * Free and realloc the buffer only if the segment_size is
+	 * changed from the previous kexec 'load' call.
+	 */
+	if (ima_kexec_file.buf && ima_kexec_file.size == segment_size)
+		goto out;
+
 	ima_free_kexec_file_buf(&ima_kexec_file);
 
 	/* segment size can't change between kexec load and execute */
@@ -41,6 +49,8 @@ static int ima_alloc_kexec_file_buf(size_t segment_size)
 		return -ENOMEM;
 
 	ima_kexec_file.size = segment_size;
+
+out:
 	ima_kexec_file.read_pos = 0;
 	ima_kexec_file.count = sizeof(struct ima_kexec_hdr);	/* reserved space */
 
-- 
2.25.1