[PATCH v7 5/6] of: kexec: Refactor IMA buffer related functions to make them reusable

Stefan Berger
2022-08-12T16:44:13Z

Refactor IMA buffer related functions to make them reusable for carrying
TPM logs across kexec.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Tested-by: Nageswara R Sastry <rnsastry@linux.ibm.com>

---
v6:
- Add __init to get_kexec_buffer as suggested by Jonathan

v5:
- Rebased on Jonathan McDowell's commit "b69a2afd5afc x86/kexec: Carry
forward IMA measurement log on kexec"
v4:
- Move debug output into setup_buffer()
---
drivers/of/kexec.c | 126 ++++++++++++++++++++++++++-------------------
1 file changed, 74 insertions(+), 52 deletions(-)

diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c
index 548dd5b1b5c1..15a82b574f36 100644
--- a/drivers/of/kexec.c
+++ b/drivers/of/kexec.c
@@ -117,45 +117,57 @@ static int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
}

#ifdef CONFIG_HAVE_IMA_KEXEC
-/**
- * ima_get_kexec_buffer - get IMA buffer from the previous kernel
- * @addr: On successful return, set to point to the buffer contents.
- * @size: On successful return, set to the buffer size.
- *
- * Return: 0 on success, negative errno on error.
- */
-int __init ima_get_kexec_buffer(void **addr, size_t *size)
+static int __init get_kexec_buffer(const char *name, unsigned long *addr,
+ size_t *size)
{
int ret, len;
- unsigned long tmp_addr;
unsigned long start_pfn, end_pfn;
- size_t tmp_size;
const void *prop;

- prop = of_get_property(of_chosen, "linux,ima-kexec-buffer", &len);
+ prop = of_get_property(of_chosen, name, &len);
if (!prop)
return -ENOENT;

- ret = do_get_kexec_buffer(prop, len, &tmp_addr, &tmp_size);
+ ret = do_get_kexec_buffer(prop, len, addr, size);
if (ret)
return ret;

- /* Do some sanity on the returned size for the ima-kexec buffer */
- if (!tmp_size)
+ /* Do some sanity on the returned size for the kexec buffer */
+ if (!*size)
return -ENOENT;

/*
* Calculate the PFNs for the buffer and ensure
* they are with in addressable memory.
*/
- start_pfn = PHYS_PFN(tmp_addr);
- end_pfn = PHYS_PFN(tmp_addr + tmp_size - 1);
+ start_pfn = PHYS_PFN(*addr);
+ end_pfn = PHYS_PFN(*addr + *size - 1);
if (!page_is_ram(start_pfn) || !page_is_ram(end_pfn)) {
- pr_warn("IMA buffer at 0x%lx, size = 0x%zx beyond memory\n",
- tmp_addr, tmp_size);
+ pr_warn("%s buffer at 0x%lx, size = 0x%zx beyond memory\n",
+ name, *addr, *size);
return -EINVAL;
}

+ return 0;
+}
+
+/**
+ * ima_get_kexec_buffer - get IMA buffer from the previous kernel
+ * @addr: On successful return, set to point to the buffer contents.
+ * @size: On successful return, set to the buffer size.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+int __init ima_get_kexec_buffer(void **addr, size_t *size)
+{
+ int ret;
+ unsigned long tmp_addr;
+ size_t tmp_size;
+
+ ret = get_kexec_buffer("linux,ima-kexec-buffer", &tmp_addr, &tmp_size);
+ if (ret)
+ return ret;
+
*addr = __va(tmp_addr);
*size = tmp_size;

@@ -188,72 +200,82 @@ int __init ima_free_kexec_buffer(void)
}
#endif

-/**
- * remove_ima_buffer - remove the IMA buffer property and reservation from @fdt
- *
- * @fdt: Flattened Device Tree to update
- * @chosen_node: Offset to the chosen node in the device tree
- *
- * The IMA measurement buffer is of no use to a subsequent kernel, so we always
- * remove it from the device tree.
- */
-static void remove_ima_buffer(void *fdt, int chosen_node)
+static int remove_buffer(void *fdt, int chosen_node, const char *name)
{
int ret, len;
unsigned long addr;
size_t size;
const void *prop;

- if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
- return;
-
- prop = fdt_getprop(fdt, chosen_node, "linux,ima-kexec-buffer", &len);
+ prop = fdt_getprop(fdt, chosen_node, name, &len);
if (!prop)
- return;
+ return -ENOENT;

ret = do_get_kexec_buffer(prop, len, &addr, &size);
- fdt_delprop(fdt, chosen_node, "linux,ima-kexec-buffer");
+ fdt_delprop(fdt, chosen_node, name);
if (ret)
- return;
+ return ret;

ret = fdt_find_and_del_mem_rsv(fdt, addr, size);
if (!ret)
- pr_debug("Removed old IMA buffer reservation.\n");
+ pr_debug("Remove old %s buffer reserveration", name);
+ return ret;
}

-#ifdef CONFIG_IMA_KEXEC
/**
- * setup_ima_buffer - add IMA buffer information to the fdt
- * @image: kexec image being loaded.
- * @fdt: Flattened device tree for the next kernel.
- * @chosen_node: Offset to the chosen node.
+ * remove_ima_buffer - remove the IMA buffer property and reservation from @fdt
*
- * Return: 0 on success, or negative errno on error.
+ * @fdt: Flattened Device Tree to update
+ * @chosen_node: Offset to the chosen node in the device tree
+ *
+ * The IMA measurement buffer is of no use to a subsequent kernel, so we always
+ * remove it from the device tree.
*/
-static int setup_ima_buffer(const struct kimage *image, void *fdt,
- int chosen_node)
+static void remove_ima_buffer(void *fdt, int chosen_node)
+{
+ if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC))
+ return;
+
+ remove_buffer(fdt, chosen_node, "linux,ima-kexec-buffer");
+}
+
+#ifdef CONFIG_IMA_KEXEC
+static int setup_buffer(void *fdt, int chosen_node, const char *name,
+ phys_addr_t addr, size_t size)
{
int ret;

- if (!image->ima_buffer_size)
+ if (!size)
return 0;

ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
- "linux,ima-kexec-buffer",
- image->ima_buffer_addr,
- image->ima_buffer_size);
+ name, addr, size);
if (ret < 0)
return -EINVAL;

- ret = fdt_add_mem_rsv(fdt, image->ima_buffer_addr,
- image->ima_buffer_size);
+ ret = fdt_add_mem_rsv(fdt, addr, size);
if (ret)
return -EINVAL;

- pr_debug("IMA buffer at 0x%pa, size = 0x%zx\n",
- &image->ima_buffer_addr, image->ima_buffer_size);
+ pr_debug("%s at 0x%pa, size = 0x%zx\n", name, &addr, size);

return 0;
+
+}
+
+/**
+ * setup_ima_buffer - add IMA buffer information to the fdt
+ * @image: kexec image being loaded.
+ * @fdt: Flattened device tree for the next kernel.
+ * @chosen_node: Offset to the chosen node.
+ *
+ * Return: 0 on success, or negative errno on error.
+ */
+static int setup_ima_buffer(const struct kimage *image, void *fdt,
+ int chosen_node)
+{
+ return setup_buffer(fdt, chosen_node, "linux,ima-kexec-buffer",
+ image->ima_buffer_addr, image->ima_buffer_size);
}
#else /* CONFIG_IMA_KEXEC */
static inline int setup_ima_buffer(const struct kimage *image, void *fdt,
--
2.35.1