Re: [PATCH v2] Carry forward IMA measurement log on kexec on x86_64

[Borislav Petkov <bp@alien8.de>]

On Tue, Apr 26, 2022 at 04:52:49PM +0000, Jonathan McDowell wrote:
> Subject: Re: [PATCH v2] Carry forward IMA measurement log on kexec on x86_64

The tip tree preferred format for patch subject prefixes is
'subsys/component:', e.g. 'x86/apic:', 'x86/mm/fault:', 'sched/fair:',
'genirq/core:'. Please do not use file names or complete file paths as
prefix. 'git log path/to/file' should give you a reasonable hint in most
cases.

The condensed patch description in the subject line should start with a
uppercase letter and should be written in imperative tone.

I guess in your case

"x86/kexec: Carry ..."

> diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h
> index b25d3f82c2f3..2f7b138a9388 100644
> --- a/arch/x86/include/uapi/asm/bootparam.h
> +++ b/arch/x86/include/uapi/asm/bootparam.h
> @@ -10,6 +10,7 @@
>  #define SETUP_EFI			4
>  #define SETUP_APPLE_PROPERTIES		5
>  #define SETUP_JAILHOUSE			6
> +#define SETUP_IMA			7

There's already

 #define SETUP_CC_BLOB                  7

in the tip tree - please redo your patch against current tip/master.

> diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
> index 170d0fd68b1f..cdc73e081585 100644
> --- a/arch/x86/kernel/kexec-bzimage64.c
> +++ b/arch/x86/kernel/kexec-bzimage64.c
> @@ -186,6 +186,32 @@ setup_efi_state(struct boot_params *params, unsigned long params_load_addr,
>  }
>  #endif /* CONFIG_EFI */
>  
> +#ifdef CONFIG_IMA_KEXEC
> +static void
> +setup_ima_state(const struct kimage *image, struct boot_params *params,

You can push that ugly ifdeffery inside the function like so:

diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
index cdc73e081585..47ba7083fd44 100644
--- a/arch/x86/kernel/kexec-bzimage64.c
+++ b/arch/x86/kernel/kexec-bzimage64.c
@@ -186,12 +186,12 @@ setup_efi_state(struct boot_params *params, unsigned long params_load_addr,
 }
 #endif /* CONFIG_EFI */
 
-#ifdef CONFIG_IMA_KEXEC
 static void
 setup_ima_state(const struct kimage *image, struct boot_params *params,
 		unsigned long params_load_addr,
 		unsigned int ima_setup_data_offset)
 {
+#ifdef CONFIG_IMA_KEXEC
 	struct setup_data *sd = (void *)params + ima_setup_data_offset;
 	struct ima_setup_data *ima = (void *)sd + sizeof(struct setup_data);
 	unsigned long setup_data_phys;
@@ -209,8 +209,8 @@ setup_ima_state(const struct kimage *image, struct boot_params *params,
 	setup_data_phys = params_load_addr + ima_setup_data_offset;
 	sd->next = params->hdr.setup_data;
 	params->hdr.setup_data = setup_data_phys;
-}
 #endif /* CONFIG_IMA_KEXEC */
+}
 
 static int
 setup_boot_parameters(struct kimage *image, struct boot_params *params,
@@ -274,13 +274,11 @@ setup_boot_parameters(struct kimage *image, struct boot_params *params,
 			efi_setup_data_offset);
 #endif
 
-#ifdef CONFIG_IMA_KEXEC
 	/* Setup IMA log buffer state */
 	setup_ima_state(image, params, params_load_addr,
 			efi_setup_data_offset +
 			sizeof(struct setup_data) +
 			sizeof(struct efi_setup_data));
-#endif
 
 	/* Setup EDD info */
 	memcpy(params->eddbuf, boot_params.eddbuf,

> +		unsigned long params_load_addr,
> +		unsigned int ima_setup_data_offset)
> +{
> +	struct setup_data *sd = (void *)params + ima_setup_data_offset;
> +	struct ima_setup_data *ima = (void *)sd + sizeof(struct setup_data);
> +	unsigned long setup_data_phys;

The tip-tree preferred ordering of variable declarations at the
beginning of a function is reverse fir tree order::

	struct long_struct_name *descriptive_name;
	unsigned long foo, bar;
	unsigned int tmp;
	int ret;

The above is faster to parse than the reverse ordering::

	int ret;
	unsigned int tmp;
	unsigned long foo, bar;
	struct long_struct_name *descriptive_name;

And even more so than random ordering::

	unsigned long foo, bar;
	int ret;
	struct long_struct_name *descriptive_name;
	unsigned int tmp;

> +
> +	if (!image->ima_buffer_size)
> +		return;
> +
> +	sd->type = SETUP_IMA;
> +	sd->len = sizeof(*ima);
> +
> +	ima->addr = image->ima_buffer_addr;
> +	ima->size = image->ima_buffer_size;
> +
> +	/* Add setup data */
> +	setup_data_phys = params_load_addr + ima_setup_data_offset;
> +	sd->next = params->hdr.setup_data;
> +	params->hdr.setup_data = setup_data_phys;
> +}
> +#endif /* CONFIG_IMA_KEXEC */
> +
>  static int
>  setup_boot_parameters(struct kimage *image, struct boot_params *params,
>  		      unsigned long params_load_addr,
> @@ -247,6 +273,15 @@ setup_boot_parameters(struct kimage *image, struct boot_params *params,
>  	setup_efi_state(params, params_load_addr, efi_map_offset, efi_map_sz,
>  			efi_setup_data_offset);
>  #endif
> +
> +#ifdef CONFIG_IMA_KEXEC
> +	/* Setup IMA log buffer state */
> +	setup_ima_state(image, params, params_load_addr,
> +			efi_setup_data_offset +
> +			sizeof(struct setup_data) +
> +			sizeof(struct efi_setup_data));
> +#endif
> +
>  	/* Setup EDD info */
>  	memcpy(params->eddbuf, boot_params.eddbuf,
>  				EDDMAXNR * sizeof(struct edd_info));
> @@ -401,7 +436,9 @@ static void *bzImage64_load(struct kimage *image, char *kernel,
>  	params_cmdline_sz = ALIGN(params_cmdline_sz, 16);
>  	kbuf.bufsz = params_cmdline_sz + ALIGN(efi_map_sz, 16) +
>  				sizeof(struct setup_data) +
> -				sizeof(struct efi_setup_data);
> +				sizeof(struct efi_setup_data) +
> +				sizeof(struct setup_data) +
> +				sizeof(struct ima_setup_data);

Just because the EFI thing did it unconditionally, regardless of
CONFIG_EFI, you don't have to copy that sloppiness:

	unsigned long ima_buf_sz = 0;

	...

	if (IS_ENABLED(CONFIG_IMA_EXEC))
		ima_buf_sz = ...

	kbuf.bufsz = ... + ima_buf_sz);

> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index c95b9ac5a457..8b0e7725f918 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -11,6 +11,7 @@
>  #include <linux/dma-map-ops.h>
>  #include <linux/dmi.h>
>  #include <linux/efi.h>
> +#include <linux/ima.h>
>  #include <linux/init_ohci1394_dma.h>
>  #include <linux/initrd.h>
>  #include <linux/iscsi_ibft.h>
> @@ -335,6 +336,28 @@ static void __init reserve_initrd(void)
>  }
>  #endif /* CONFIG_BLK_DEV_INITRD */
>  
> +#ifdef CONFIG_IMA_KEXEC
> +static void __init add_early_ima_buffer(u64 phys_addr)
> +{
> +	struct ima_setup_data *data;
> +
> +	data = early_memremap(phys_addr + sizeof(struct setup_data),
> +			      sizeof(*data));
> +	if (!data) {
> +		pr_warn("setup: failed to memremap ima_setup_data entry\n");
> +		return;
> +	}
> +	memblock_reserve(data->addr, data->size);
> +	ima_set_kexec_buffer(data->addr, data->size);
> +	early_memunmap(data, sizeof(*data));
> +}
> +#else
> +static void __init add_early_ima_buffer(u64 phys_addr)
> +{
> +	pr_warn("Passed IMA kexec data, but CONFIG_IMA_KEXEC not set. Ignoring.\n");
> +}
> +#endif

ditto:

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 9324c30755c5..32403d693bf3 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -336,9 +336,9 @@ static void __init reserve_initrd(void)
 }
 #endif /* CONFIG_BLK_DEV_INITRD */
 
-#ifdef CONFIG_IMA_KEXEC
 static void __init add_early_ima_buffer(u64 phys_addr)
 {
+#ifdef CONFIG_IMA_KEXEC
        struct ima_setup_data *data;
 
        data = early_memremap(phys_addr + sizeof(struct setup_data),
@@ -350,13 +350,10 @@ static void __init add_early_ima_buffer(u64 phys_addr)
        memblock_reserve(data->addr, data->size);
        ima_set_kexec_buffer(data->addr, data->size);
        early_memunmap(data, sizeof(*data));
-}
 #else
-static void __init add_early_ima_buffer(u64 phys_addr)
-{
        pr_warn("Passed IMA kexec data, but CONFIG_IMA_KEXEC not set. Ignoring.\n");
-}
 #endif
+}
 
 static void __init parse_setup_data(void)
 {

> 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)

WARNING: modpost: vmlinux.o(.text+0xe4e785): Section mismatch in reference from the function ima_free_kexec_buffer() to the function .meminit.text:memblock_phys_free()
The function ima_free_kexec_buffer() references
the function __meminit memblock_phys_free().
This is often because ima_free_kexec_buffer lacks a __meminit 
annotation or the annotation of memblock_phys_free is wrong.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette