Re: [PATCH v12 2/4] powerpc: Move arch independent ima kexec functions to drivers/of/kexec.c
From: Lakshmi Ramasubramanian
Date: Thu Dec 17 2020 - 15:53:19 EST
On 12/17/20 12:05 PM, Rob Herring wrote:
On Thu, Dec 17, 2020 at 09:37:06AM -0800, Lakshmi Ramasubramanian wrote:
The functions defined in "arch/powerpc/kexec/ima.c" handle setting up
and freeing the resources required to carry over the IMA measurement
list from the current kernel to the next kernel across kexec system call.
These functions do not have architecture specific code, but are
currently limited to powerpc.
Move setup_ima_buffer() call into of_kexec_setup_new_fdt().
Move architecture independent functions from "arch/powerpc/kexec/ima.c"
to "drivers/of/kexec.c". Delete "arch/powerpc/kexec/ima.c" and
"arch/powerpc/include/asm/ima.h". Remove references to the deleted files
in powerpc and in ima.
delete_fdt_mem_rsv() defined in "arch/powerpc/kexec/file_load.c"
is not used anymore. Remove this function.
I think this patch should come first and then patch 1. Move then rework
the code.
Sure - will reorder the patches.
Signed-off-by: Lakshmi Ramasubramanian <nramas@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/include/asm/ima.h | 30 -----
arch/powerpc/include/asm/kexec.h | 1 -
arch/powerpc/kexec/Makefile | 7 -
arch/powerpc/kexec/file_load.c | 39 ------
arch/powerpc/kexec/ima.c | 182 --------------------------
drivers/of/kexec.c | 198 +++++++++++++++++++++++++++++
include/linux/of.h | 17 +++
security/integrity/ima/ima.h | 4 -
security/integrity/ima/ima_kexec.c | 2 +
9 files changed, 217 insertions(+), 263 deletions(-)
delete mode 100644 arch/powerpc/include/asm/ima.h
delete mode 100644 arch/powerpc/kexec/ima.c
diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c
index 66787be081fe..a6ab35f16dd2 100644
--- a/drivers/of/kexec.c
+++ b/drivers/of/kexec.c
@@ -10,10 +10,12 @@
*/
#include <linux/kernel.h>
+#include <linux/slab.h>
#include <linux/kexec.h>
#include <linux/libfdt.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
+#include <linux/memblock.h>
#include <linux/random.h>
#include <linux/types.h>
@@ -59,6 +61,141 @@ static int fdt_find_and_del_mem_rsv(void *fdt, unsigned long start, unsigned lon
return -ENOENT;
}
+/**
+ * get_addr_size_cells - Get address and size of root node
+ *
+ * @addr_cells: Return address of the root node
+ * @size_cells: Return size of the root node
+ *
+ * Return: 0 on success, or negative errno on error.
+ */
+static int get_addr_size_cells(int *addr_cells, int *size_cells)
+{
+ struct device_node *root;
+
+ root = of_find_node_by_path("/");
+ if (!root)
+ return -EINVAL;
+
+ *addr_cells = of_n_addr_cells(root);
+ *size_cells = of_n_size_cells(root);
+
+ of_node_put(root);
+
+ return 0;
+}
+
+/**
+ * do_get_kexec_buffer - Get address and size of device tree property
+ *
+ * @prop: Device tree property
+ * @len: Size of @prop
+ * @addr: Return address of the node
+ * @size: Return size of the node
+ *
+ * Return: 0 on success, or negative errno on error.
+ */
+static int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
+ size_t *size)
+{
+ int ret, addr_cells, size_cells;
+
+ ret = get_addr_size_cells(&addr_cells, &size_cells);
+ if (ret)
+ return ret;
+
+ if (len < 4 * (addr_cells + size_cells))
+ return -ENOENT;
+
+ *addr = of_read_number(prop, addr_cells);
+ *size = of_read_number(prop + 4 * addr_cells, size_cells);
+
+ 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 ima_get_kexec_buffer(void **addr, size_t *size)
+{
+ int ret, len;
+ unsigned long tmp_addr;
+ size_t tmp_size;
+ const void *prop;
+
+ prop = of_get_property(of_chosen, "linux,ima-kexec-buffer", &len);
+ if (!prop)
+ return -ENOENT;
+
+ ret = do_get_kexec_buffer(prop, len, &tmp_addr, &tmp_size);
+ if (ret)
+ return ret;
+
+ *addr = __va(tmp_addr);
+ *size = tmp_size;
+
+ return 0;
+}
+
+/**
+ * ima_free_kexec_buffer - free memory used by the IMA buffer
+ */
+int ima_free_kexec_buffer(void)
+{
+ int ret;
+ unsigned long addr;
+ size_t size;
+ struct property *prop;
+
+ prop = of_find_property(of_chosen, "linux,ima-kexec-buffer", NULL);
+ if (!prop)
+ return -ENOENT;
+
+ ret = do_get_kexec_buffer(prop->value, prop->length, &addr, &size);
+ if (ret)
+ return ret;
+
+ ret = of_remove_property(of_chosen, prop);
+ if (ret)
+ return ret;
+
+ return memblock_free(addr, size);
+}
+
+/**
+ * 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.
+ */
+void remove_ima_buffer(void *fdt, int chosen_node)
static
Will update.
+{
+ int ret, len;
+ unsigned long addr;
+ size_t size;
+ const void *prop;
+
+ prop = fdt_getprop(fdt, chosen_node, "linux,ima-kexec-buffer", &len);
+ if (!prop)
+ return;
+
+ ret = do_get_kexec_buffer(prop, len, &addr, &size);
+ fdt_delprop(fdt, chosen_node, "linux,ima-kexec-buffer");
+ if (ret)
+ return;
+
+ ret = fdt_find_and_del_mem_rsv(fdt, addr, size);
+ if (!ret)
+ pr_debug("Removed old IMA buffer reservation.\n");
+}
All the above needs to be in an '#ifdef CONFIG_IMA_KEXEC'.
remove_ima_buffer() needs to be defined when CONFIG_HAVE_IMA_KEXEC is
enabled. CONFIG_HAVE_IMA_KEXEC can be enabled even if CONFIG_IMA_KEXEC
is not.
I'll move remove_ima_buffer() under "#ifdef CONFIG_HAVE_IMA_KEXEC" in
this file.
+
/*
* of_kexec_setup_new_fdt - modify /chosen and memory reservation for the next kernel
*
@@ -219,6 +356,10 @@ int of_kexec_setup_new_fdt(const struct kimage *image, void *fdt,
}
ret = fdt_setprop(fdt, chosen_node, "linux,booted-from-kexec", NULL, 0);
+ if (ret)
+ goto out;
+
+ ret = setup_ima_buffer(image, fdt, fdt_path_offset(fdt, "/chosen"));
out:
if (ret)
@@ -226,3 +367,60 @@ int of_kexec_setup_new_fdt(const struct kimage *image, void *fdt,
return 0;
}
+
+#ifdef CONFIG_IMA_KEXEC
+/**
+ * arch_ima_add_kexec_buffer - do arch-specific steps to add the IMA buffer
+ *
+ * @image: kimage struct to set IMA buffer data
+ * @load_addr: Starting address where IMA buffer is loaded at
+ * @size: Number of bytes in the IMA buffer
+ *
+ * Architectures should use this function to pass on the IMA buffer
+ * information to the next kernel.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+int arch_ima_add_kexec_buffer(struct kimage *image, unsigned long load_addr,
+ size_t size)
This should be a static inline in asm/kexec.h.
arch_ima_add_kexec_buffer() is identical for powerpc and arm64.
Would it be better to "static inline" this function in "of.h" instead of
duplicating it in "asm/kexec.h" for powerpc and arm64?
+{
+ image->arch.ima_buffer_addr = load_addr;
+ image->arch.ima_buffer_size = 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.
+ */
+int setup_ima_buffer(const struct kimage *image, void *fdt, int chosen_node)
static
Will update.
+{
+ int ret;
+
+ remove_ima_buffer(fdt, chosen_node);
+ if (!image->arch.ima_buffer_size)
+ return 0;
+
+ ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
+ "linux,ima-kexec-buffer",
+ image->arch.ima_buffer_addr,
+ image->arch.ima_buffer_size);
+ if (ret)
+ return (ret == -FDT_ERR_NOSPACE ? -ENOMEM : -EINVAL);
+
+ ret = fdt_add_mem_rsv(fdt, image->arch.ima_buffer_addr,
+ image->arch.ima_buffer_size);
+ if (ret)
+ return -EINVAL;
+
+ pr_debug("IMA buffer at 0x%llx, size = 0x%zx\n",
+ image->arch.ima_buffer_addr, image->arch.ima_buffer_size);
+
+ return 0;
+}
+#endif /* CONFIG_IMA_KEXEC */
diff --git a/include/linux/of.h b/include/linux/of.h
index 3375f5295875..7477f2266d8f 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -562,6 +562,23 @@ struct kimage;
int of_kexec_setup_new_fdt(const struct kimage *image, void *fdt,
unsigned long initrd_load_addr, unsigned long initrd_len,
const char *cmdline);
+int ima_get_kexec_buffer(void **addr, size_t *size);
+int ima_free_kexec_buffer(void);
+void remove_ima_buffer(void *fdt, int chosen_node);
+
+#ifdef CONFIG_IMA_KEXEC
+int arch_ima_add_kexec_buffer(struct kimage *image,
+ unsigned long load_addr,
+ size_t size);
+int setup_ima_buffer(const struct kimage *image, void *fdt, int chosen_node);
This doesn't need to be public.
Will update.
thanks,
-lakshmi
+#else
+static inline int setup_ima_buffer(const struct kimage *image, void *fdt,
+ int chosen_node)
+{
+ remove_ima_buffer(fdt, chosen_node);
+ return 0;
+}
+#endif /* CONFIG_IMA_KEXEC */
#else /* CONFIG_OF */
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 6ebefec616e4..7c3947ad3773 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -24,10 +24,6 @@
#include "../integrity.h"
-#ifdef CONFIG_HAVE_IMA_KEXEC
-#include <asm/ima.h>
-#endif
-
enum ima_show_type { IMA_SHOW_BINARY, IMA_SHOW_BINARY_NO_FIELD_LEN,
IMA_SHOW_BINARY_OLD_STRING_FMT, IMA_SHOW_ASCII };
enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8, TPM_PCR10 = 10 };
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index 121de3e04af2..3d6a8820e2a5 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -9,7 +9,9 @@
#include <linux/seq_file.h>
#include <linux/vmalloc.h>
+#include <linux/of.h>
#include <linux/kexec.h>
+#include <linux/ima.h>
#include "ima.h"
#ifdef CONFIG_IMA_KEXEC
--
2.29.2