[PATCH v3 6/7] arm64: efi/libstub: use EFI_LOADER_CODE region when moving the kernel in memory

Ard Biesheuvel
2022-08-27T15:59:20Z

The EFI spec is not very clear about which permissions are being given
when allocating pages of a certain type. However, it is quite obvious
that EFI_LOADER_CODE is more likely to permit execution than
EFI_LOADER_DATA, which becomes relevant once we permit booting the
kernel proper with the firmware's 1:1 mapping still active.

(Note that GRUB for arm64 uses EFI_LOADER_CODE allocations for its
executable modules, and therefore relies on these regions having the
right permissions as well)

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
drivers/firmware/efi/libstub/alignedmem.c | 5 +++--
drivers/firmware/efi/libstub/arm64-stub.c | 6 ++++--
drivers/firmware/efi/libstub/efistub.h | 6 ++++--
drivers/firmware/efi/libstub/mem.c | 3 ++-
drivers/firmware/efi/libstub/randomalloc.c | 5 +++--
5 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/drivers/firmware/efi/libstub/alignedmem.c b/drivers/firmware/efi/libstub/alignedmem.c
index 1de9878ddd3a..174832661251 100644
--- a/drivers/firmware/efi/libstub/alignedmem.c
+++ b/drivers/firmware/efi/libstub/alignedmem.c
@@ -22,7 +22,8 @@
* Return: status code
*/
efi_status_t efi_allocate_pages_aligned(unsigned long size, unsigned long *addr,
- unsigned long max, unsigned long align)
+ unsigned long max, unsigned long align,
+ int memory_type)
{
efi_physical_addr_t alloc_addr;
efi_status_t status;
@@ -36,7 +37,7 @@ efi_status_t efi_allocate_pages_aligned(unsigned long size, unsigned long *addr,
slack = align / EFI_PAGE_SIZE - 1;

status = efi_bs_call(allocate_pages, EFI_ALLOCATE_MAX_ADDRESS,
- EFI_LOADER_DATA, size / EFI_PAGE_SIZE + slack,
+ memory_type, size / EFI_PAGE_SIZE + slack,
&alloc_addr);
if (status != EFI_SUCCESS)
return status;
diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c
index ad7392e6c200..f32e89b4049f 100644
--- a/drivers/firmware/efi/libstub/arm64-stub.c
+++ b/drivers/firmware/efi/libstub/arm64-stub.c
@@ -140,7 +140,8 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
* locate the kernel at a randomized offset in physical memory.
*/
status = efi_random_alloc(*reserve_size, min_kimg_align,
- reserve_addr, phys_seed);
+ reserve_addr, phys_seed,
+ EFI_LOADER_CODE);
if (status != EFI_SUCCESS)
efi_warn("efi_random_alloc() failed: 0x%lx\n", status);
} else {
@@ -161,7 +162,8 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
}

status = efi_allocate_pages_aligned(*reserve_size, reserve_addr,
- ULONG_MAX, min_kimg_align);
+ ULONG_MAX, min_kimg_align,
+ EFI_LOADER_CODE);

if (status != EFI_SUCCESS) {
efi_err("Failed to relocate kernel\n");
diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index b0ae0a454404..ab9e990447d3 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -871,7 +871,8 @@ void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
efi_status_t efi_get_random_bytes(unsigned long size, u8 *out);

efi_status_t efi_random_alloc(unsigned long size, unsigned long align,
- unsigned long *addr, unsigned long random_seed);
+ unsigned long *addr, unsigned long random_seed,
+ int memory_type);

efi_status_t check_platform_features(void);

@@ -895,7 +896,8 @@ efi_status_t efi_allocate_pages(unsigned long size, unsigned long *addr,
unsigned long max);

efi_status_t efi_allocate_pages_aligned(unsigned long size, unsigned long *addr,
- unsigned long max, unsigned long align);
+ unsigned long max, unsigned long align,
+ int memory_type);

efi_status_t efi_low_alloc_above(unsigned long size, unsigned long align,
unsigned long *addr, unsigned long min);
diff --git a/drivers/firmware/efi/libstub/mem.c b/drivers/firmware/efi/libstub/mem.c
index feef8d4be113..1e543c90c0ea 100644
--- a/drivers/firmware/efi/libstub/mem.c
+++ b/drivers/firmware/efi/libstub/mem.c
@@ -96,7 +96,8 @@ efi_status_t efi_allocate_pages(unsigned long size, unsigned long *addr,

if (EFI_ALLOC_ALIGN > EFI_PAGE_SIZE)
return efi_allocate_pages_aligned(size, addr, max,
- EFI_ALLOC_ALIGN);
+ EFI_ALLOC_ALIGN,
+ EFI_LOADER_DATA);

alloc_addr = ALIGN_DOWN(max + 1, EFI_ALLOC_ALIGN) - 1;
status = efi_bs_call(allocate_pages, EFI_ALLOCATE_MAX_ADDRESS,
diff --git a/drivers/firmware/efi/libstub/randomalloc.c b/drivers/firmware/efi/libstub/randomalloc.c
index 715f37479154..ca859e63bac2 100644
--- a/drivers/firmware/efi/libstub/randomalloc.c
+++ b/drivers/firmware/efi/libstub/randomalloc.c
@@ -53,7 +53,8 @@ static unsigned long get_entry_num_slots(efi_memory_desc_t *md,
efi_status_t efi_random_alloc(unsigned long size,
unsigned long align,
unsigned long *addr,
- unsigned long random_seed)
+ unsigned long random_seed,
+ int memory_type)
{
unsigned long map_size, desc_size, total_slots = 0, target_slot;
unsigned long total_mirrored_slots = 0;
@@ -127,7 +128,7 @@ efi_status_t efi_random_alloc(unsigned long size,
pages = size / EFI_PAGE_SIZE;

status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
- EFI_LOADER_DATA, pages, &target);
+ memory_type, pages, &target);
if (status == EFI_SUCCESS)
*addr = target;
break;
--
2.35.1