On Fri, Apr 29, 2022 at 05:30:10PM -0400, Mimi Zohar wrote:

quoted

diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index 13753136f03f..419c50cfe6b9 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c

@@ -10,6 +10,7 @@
 #include <linux/seq_file.h>
 #include <linux/vmalloc.h>
 #include <linux/kexec.h>
+#include <linux/memblock.h>
 #include <linux/of.h>
 #include <linux/ima.h>
 #include "ima.h"

@@ -134,10 +135,66 @@ void ima_add_kexec_buffer(struct kimage *image)
 }
 #endif /* IMA_KEXEC */
 
+#ifndef CONFIG_OF
+static phys_addr_t ima_early_kexec_buffer_phys;
+static size_t ima_early_kexec_buffer_size;
+
+void __init ima_set_kexec_buffer(phys_addr_t phys_addr, size_t size)
+{
+	if (size == 0)
+		return;
+
+	ima_early_kexec_buffer_phys = phys_addr;
+	ima_early_kexec_buffer_size = size;
+}
+
+int __init ima_free_kexec_buffer(void)
+{
+	int rc;
+
+	if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
+		return -ENOTSUPP;
+
+	if (ima_early_kexec_buffer_size == 0)
+		return -ENOENT;
+
+	rc = memblock_phys_free(ima_early_kexec_buffer_phys,
+				ima_early_kexec_buffer_size);
+	if (rc)
+		return rc;
+
+	ima_early_kexec_buffer_phys = 0;
+	ima_early_kexec_buffer_size = 0;
+
+	return 0;
+}
+
+int __init ima_get_kexec_buffer(void **addr, size_t *size)
+{
+	if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
+		return -ENOTSUPP;
+
+	if (ima_early_kexec_buffer_size == 0)
+		return -ENOENT;
+
+	*addr = __va(ima_early_kexec_buffer_phys);
+	*size = ima_early_kexec_buffer_size;
+
+	return 0;
+}
+

Originally both ima_get_kexec_buffer() and ima_free_kexec_buffer() were
architecture specific.  Refer to commit 467d27824920 ("powerpc: ima:
get the kexec buffer passed by the previous kernel").  Is there any
need for defining them here behind an "#ifndef CONFIG_OF"?

Commit fee3ff99bc67 (powerpc: Move arch independent ima kexec functions
to drivers/of/kexec.c) moved those functions to drivers/of/kexec.c as a
more generic implementation so that ARM64 could use them too.

I think for platforms that use device tree that's the way to go, but the
functions to generically set + get the IMA buffer for non device tree
systems were useful enough to put in the IMA code rather than being x86
specific. If you disagree I can move them under arch/x86/ (assuming the
x86 folk agree using setup_data is the right way to go, I haven't seen
any of them comment on this approach yet).

quoted

+#else
+
+void __init ima_set_kexec_buffer(phys_addr_t phys_addr, size_t size)
+{
+	pr_warn("CONFIG_OF enabled, ignoring call to set buffer details.\n");
+}
+#endif /* CONFIG_OF */
+

Only when "HAVE_IMA_KEXEC" is defined is this file included.  Why is
this warning needed?

x86 *can* have device tree enabled, but the only platform I'm aware that
did it was OLPC and I haven't seen any of the distros enable it. I put
this in so there's a warning if we have CONFIG_OF enabled on x86 and
tried to pass the IMA log via setup_data. Can remove (or fold into the
x86 code if we go that way).

quoted

 /*
  * Restore the measurement list from the previous kernel.
  */
-void ima_load_kexec_buffer(void)
+void __init ima_load_kexec_buffer(void)
 {
 	void *kexec_buffer = NULL;
 	size_t kexec_buffer_size = 0;

J.