There is no existing IMA functionality to just populate the buffer at
kexec execute with IMA measurements.
Implement a function to iterate over ima_measurements and populate the
ima_kexec_file buffer. After the loop, populate ima_khdr with buffer
details (version, buffer size, number of measurements). Copy the ima_khdr
data into ima_kexec_file.buf and update buffer_size and buffer.
The patch assumes that the ima_kexec_file.size is sufficient to hold all
the measurements. It returns an error and does not handle scenarios where
additional space might be needed.
Signed-off-by: Tushar Sugandhi <tusha...@linux.microsoft.com>
---
security/integrity/ima/ima_kexec.c | 52 ++++++++++++++++++++++++++++++
1 file changed, 52 insertions(+)
diff --git a/security/integrity/ima/ima_kexec.c
b/security/integrity/ima/ima_kexec.c
index 48a683874044..858b67689701 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -62,6 +62,58 @@ static int ima_allocate_buf_at_kexec_load(void)
return 0;
}
+static int ima_populate_buf_at_kexec_execute(unsigned long *buffer_size, void
**buffer)
+{
+ struct ima_queue_entry *qe;
+ int ret = 0;
+
+ /*
+ * Ensure the kexec buffer is large enough to hold ima_khdr
+ */
+ if (ima_kexec_file.size < sizeof(ima_khdr)) {
+ pr_err("%s: Kexec buffer size too low to hold ima_khdr\n",
+ __func__);
+ ima_clear_kexec_file();
+ return -ENOMEM;
+ }
+
+ list_for_each_entry_rcu(qe, &ima_measurements, later) {
+ if (ima_kexec_file.count < ima_kexec_file.size) {
+ ima_khdr.count++;
+ ima_measurements_show(&ima_kexec_file, qe);
+ } else {
+ ret = -ENOMEM;
+ pr_err("%s: Kexec ima_measurements buffer too small\n",
+ __func__);
+ break;
+ }
+ }
+ if (ret < 0)
+ goto out;
+
+ /*
+ * fill in reserved space with some buffer details
+ * (eg. version, buffer size, number of measurements)
+ */
+ ima_khdr.buffer_size = ima_kexec_file.count;
+ if (ima_canonical_fmt) {
+ ima_khdr.version = cpu_to_le16(ima_khdr.version);
+ ima_khdr.count = cpu_to_le64(ima_khdr.count);
+ ima_khdr.buffer_size = cpu_to_le64(ima_khdr.buffer_size);
+ }
+
+ memcpy(ima_kexec_file.buf, &ima_khdr, sizeof(ima_khdr));
+ *buffer_size = ima_kexec_file.count;
+ *buffer = ima_kexec_file.buf;
+
+out:
+ if (ret < 0)
+ ima_clear_kexec_file();
+
+ return ret;
+}
+
+
static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
unsigned long segment_size)
{
--
2.25.1
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