| Message ID | 20230722123850.634544-4-alexghiti@rivosinc.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | riscv: Introduce KASLR | expand |
On Sat, 22 Jul 2023 at 14:42, Alexandre Ghiti <alexghiti@rivosinc.com> wrote: > > This prepares for riscv to use the same functions to handle the pĥysical > kernel move when KASLR is enabled. > > Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> This looks fine to me. I can stick this on a stable branch in the EFI tree, but I don't have anything queued up for the next window anyway, so you might as well just take it directly. Acked-by: Ard Biesheuvel <ardb@kernel.org> > --- > arch/arm64/include/asm/efi.h | 2 + > drivers/firmware/efi/libstub/Makefile | 2 +- > drivers/firmware/efi/libstub/arm64-stub.c | 117 ++-------------- > drivers/firmware/efi/libstub/efistub.h | 8 ++ > drivers/firmware/efi/libstub/kaslr.c | 159 ++++++++++++++++++++++ > 5 files changed, 183 insertions(+), 105 deletions(-) > create mode 100644 drivers/firmware/efi/libstub/kaslr.c > > diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h > index 4cf2cb053bc8..46273ee89445 100644 > --- a/arch/arm64/include/asm/efi.h > +++ b/arch/arm64/include/asm/efi.h > @@ -168,4 +168,6 @@ static inline void efi_capsule_flush_cache_range(void *addr, int size) > > efi_status_t efi_handle_corrupted_x18(efi_status_t s, const char *f); > > +void efi_icache_sync(unsigned long start, unsigned long end); > + > #endif /* _ASM_EFI_H */ > diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile > index 16d64a34d1e1..11aba8a041ec 100644 > --- a/drivers/firmware/efi/libstub/Makefile > +++ b/drivers/firmware/efi/libstub/Makefile > @@ -86,7 +86,7 @@ lib-$(CONFIG_EFI_GENERIC_STUB) += efi-stub.o string.o intrinsics.o systable.o \ > screen_info.o efi-stub-entry.o > > lib-$(CONFIG_ARM) += arm32-stub.o > -lib-$(CONFIG_ARM64) += arm64.o arm64-stub.o smbios.o > +lib-$(CONFIG_ARM64) += kaslr.o arm64.o arm64-stub.o smbios.o > lib-$(CONFIG_X86) += x86-stub.o > lib-$(CONFIG_RISCV) += riscv.o riscv-stub.o > lib-$(CONFIG_LOONGARCH) += loongarch.o loongarch-stub.o > diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c > index 770b8ecb7398..452b7ccd330e 100644 > --- a/drivers/firmware/efi/libstub/arm64-stub.c > +++ b/drivers/firmware/efi/libstub/arm64-stub.c > @@ -14,42 +14,6 @@ > > #include "efistub.h" > > -/* > - * Distro versions of GRUB may ignore the BSS allocation entirely (i.e., fail > - * to provide space, and fail to zero it). Check for this condition by double > - * checking that the first and the last byte of the image are covered by the > - * same EFI memory map entry. > - */ > -static bool check_image_region(u64 base, u64 size) > -{ > - struct efi_boot_memmap *map; > - efi_status_t status; > - bool ret = false; > - int map_offset; > - > - status = efi_get_memory_map(&map, false); > - if (status != EFI_SUCCESS) > - return false; > - > - for (map_offset = 0; map_offset < map->map_size; map_offset += map->desc_size) { > - efi_memory_desc_t *md = (void *)map->map + map_offset; > - u64 end = md->phys_addr + md->num_pages * EFI_PAGE_SIZE; > - > - /* > - * Find the region that covers base, and return whether > - * it covers base+size bytes. > - */ > - if (base >= md->phys_addr && base < end) { > - ret = (base + size) <= end; > - break; > - } > - } > - > - efi_bs_call(free_pool, map); > - > - return ret; > -} > - > efi_status_t handle_kernel_image(unsigned long *image_addr, > unsigned long *image_size, > unsigned long *reserve_addr, > @@ -59,31 +23,6 @@ efi_status_t handle_kernel_image(unsigned long *image_addr, > { > efi_status_t status; > unsigned long kernel_size, kernel_codesize, kernel_memsize; > - u32 phys_seed = 0; > - u64 min_kimg_align = efi_get_kimg_min_align(); > - > - if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { > - efi_guid_t li_fixed_proto = LINUX_EFI_LOADED_IMAGE_FIXED_GUID; > - void *p; > - > - if (efi_nokaslr) { > - efi_info("KASLR disabled on kernel command line\n"); > - } else if (efi_bs_call(handle_protocol, image_handle, > - &li_fixed_proto, &p) == EFI_SUCCESS) { > - efi_info("Image placement fixed by loader\n"); > - } else { > - status = efi_get_random_bytes(sizeof(phys_seed), > - (u8 *)&phys_seed); > - if (status == EFI_NOT_FOUND) { > - efi_info("EFI_RNG_PROTOCOL unavailable\n"); > - efi_nokaslr = true; > - } else if (status != EFI_SUCCESS) { > - efi_err("efi_get_random_bytes() failed (0x%lx)\n", > - status); > - efi_nokaslr = true; > - } > - } > - } > > if (image->image_base != _text) { > efi_err("FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value\n"); > @@ -98,50 +37,15 @@ efi_status_t handle_kernel_image(unsigned long *image_addr, > kernel_codesize = __inittext_end - _text; > kernel_memsize = kernel_size + (_end - _edata); > *reserve_size = kernel_memsize; > + *image_addr = (unsigned long)_text; > > - if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) { > - /* > - * If KASLR is enabled, and we have some randomness available, > - * locate the kernel at a randomized offset in physical memory. > - */ > - status = efi_random_alloc(*reserve_size, min_kimg_align, > - reserve_addr, phys_seed, > - EFI_LOADER_CODE); > - if (status != EFI_SUCCESS) > - efi_warn("efi_random_alloc() failed: 0x%lx\n", status); > - } else { > - status = EFI_OUT_OF_RESOURCES; > - } > - > - if (status != EFI_SUCCESS) { > - if (!check_image_region((u64)_text, kernel_memsize)) { > - efi_err("FIRMWARE BUG: Image BSS overlaps adjacent EFI memory region\n"); > - } else if (IS_ALIGNED((u64)_text, min_kimg_align) && > - (u64)_end < EFI_ALLOC_LIMIT) { > - /* > - * Just execute from wherever we were loaded by the > - * UEFI PE/COFF loader if the placement is suitable. > - */ > - *image_addr = (u64)_text; > - *reserve_size = 0; > - return EFI_SUCCESS; > - } > - > - status = efi_allocate_pages_aligned(*reserve_size, reserve_addr, > - ULONG_MAX, min_kimg_align, > - EFI_LOADER_CODE); > - > - if (status != EFI_SUCCESS) { > - efi_err("Failed to relocate kernel\n"); > - *reserve_size = 0; > - return status; > - } > - } > - > - *image_addr = *reserve_addr; > - memcpy((void *)*image_addr, _text, kernel_size); > - caches_clean_inval_pou(*image_addr, *image_addr + kernel_codesize); > - efi_remap_image(*image_addr, *reserve_size, kernel_codesize); > + status = efi_kaslr_relocate_kernel(image_addr, > + reserve_addr, reserve_size, > + kernel_size, kernel_codesize, > + kernel_memsize, > + efi_kaslr_get_phys_seed(image_handle)); > + if (status != EFI_SUCCESS) > + return status; > > return EFI_SUCCESS; > } > @@ -159,3 +63,8 @@ unsigned long primary_entry_offset(void) > */ > return (char *)primary_entry - _text; > } > + > +void efi_icache_sync(unsigned long start, unsigned long end) > +{ > + caches_clean_inval_pou(start, end); > +} > diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h > index 6aa38a1bf126..b1a1037567ba 100644 > --- a/drivers/firmware/efi/libstub/efistub.h > +++ b/drivers/firmware/efi/libstub/efistub.h > @@ -1132,6 +1132,14 @@ const u8 *__efi_get_smbios_string(const struct efi_smbios_record *record, > > void efi_remap_image(unsigned long image_base, unsigned alloc_size, > unsigned long code_size); > +efi_status_t efi_kaslr_relocate_kernel(unsigned long *image_addr, > + unsigned long *reserve_addr, > + unsigned long *reserve_size, > + unsigned long kernel_size, > + unsigned long kernel_codesize, > + unsigned long kernel_memsize, > + u32 phys_seed); > +u32 efi_kaslr_get_phys_seed(efi_handle_t image_handle); > > asmlinkage efi_status_t __efiapi > efi_zboot_entry(efi_handle_t handle, efi_system_table_t *systab); > diff --git a/drivers/firmware/efi/libstub/kaslr.c b/drivers/firmware/efi/libstub/kaslr.c > new file mode 100644 > index 000000000000..be0c8ab0982a > --- /dev/null > +++ b/drivers/firmware/efi/libstub/kaslr.c > @@ -0,0 +1,159 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Helper functions used by the EFI stub on multiple > + * architectures to deal with physical address space randomization. > + */ > +#include <linux/efi.h> > + > +#include "efistub.h" > + > +/** > + * efi_kaslr_get_phys_seed() - Get random seed for physical kernel KASLR > + * @image_handle: Handle to the image > + * > + * If KASLR is not disabled, obtain a random seed using EFI_RNG_PROTOCOL > + * that will be used to move the kernel physical mapping. > + * > + * Return: the random seed > + */ > +u32 efi_kaslr_get_phys_seed(efi_handle_t image_handle) > +{ > + efi_status_t status; > + u32 phys_seed; > + efi_guid_t li_fixed_proto = LINUX_EFI_LOADED_IMAGE_FIXED_GUID; > + void *p; > + > + if (!IS_ENABLED(CONFIG_RANDOMIZE_BASE)) > + return 0; > + > + if (efi_nokaslr) { > + efi_info("KASLR disabled on kernel command line\n"); > + } else if (efi_bs_call(handle_protocol, image_handle, > + &li_fixed_proto, &p) == EFI_SUCCESS) { > + efi_info("Image placement fixed by loader\n"); > + } else { > + status = efi_get_random_bytes(sizeof(phys_seed), > + (u8 *)&phys_seed); > + if (status == EFI_SUCCESS) { > + return phys_seed; > + } else if (status == EFI_NOT_FOUND) { > + efi_info("EFI_RNG_PROTOCOL unavailable\n"); > + efi_nokaslr = true; > + } else if (status != EFI_SUCCESS) { > + efi_err("efi_get_random_bytes() failed (0x%lx)\n", > + status); > + efi_nokaslr = true; > + } > + } > + > + return 0; > +} > + > +/* > + * Distro versions of GRUB may ignore the BSS allocation entirely (i.e., fail > + * to provide space, and fail to zero it). Check for this condition by double > + * checking that the first and the last byte of the image are covered by the > + * same EFI memory map entry. > + */ > +static bool check_image_region(u64 base, u64 size) > +{ > + struct efi_boot_memmap *map; > + efi_status_t status; > + bool ret = false; > + int map_offset; > + > + status = efi_get_memory_map(&map, false); > + if (status != EFI_SUCCESS) > + return false; > + > + for (map_offset = 0; map_offset < map->map_size; map_offset += map->desc_size) { > + efi_memory_desc_t *md = (void *)map->map + map_offset; > + u64 end = md->phys_addr + md->num_pages * EFI_PAGE_SIZE; > + > + /* > + * Find the region that covers base, and return whether > + * it covers base+size bytes. > + */ > + if (base >= md->phys_addr && base < end) { > + ret = (base + size) <= end; > + break; > + } > + } > + > + efi_bs_call(free_pool, map); > + > + return ret; > +} > + > +/** > + * efi_kaslr_relocate_kernel() - Relocate the kernel (random if KASLR enabled) > + * @image_addr: Pointer to the current kernel location > + * @reserve_addr: Pointer to the relocated kernel location > + * @reserve_size: Size of the relocated kernel > + * @kernel_size: Size of the text + data > + * @kernel_codesize: Size of the text > + * @kernel_memsize: Size of the text + data + bss > + * @phys_seed: Random seed used for the relocation > + * > + * If KASLR is not enabled, this function relocates the kernel to a fixed > + * address (or leave it as its current location). If KASLR is enabled, the > + * kernel physical location is randomized using the seed in parameter. > + * > + * Return: status code, EFI_SUCCESS if relocation is successful > + */ > +efi_status_t efi_kaslr_relocate_kernel(unsigned long *image_addr, > + unsigned long *reserve_addr, > + unsigned long *reserve_size, > + unsigned long kernel_size, > + unsigned long kernel_codesize, > + unsigned long kernel_memsize, > + u32 phys_seed) > +{ > + efi_status_t status; > + u64 min_kimg_align = efi_get_kimg_min_align(); > + > + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) { > + /* > + * If KASLR is enabled, and we have some randomness available, > + * locate the kernel at a randomized offset in physical memory. > + */ > + status = efi_random_alloc(*reserve_size, min_kimg_align, > + reserve_addr, phys_seed, > + EFI_LOADER_CODE); > + if (status != EFI_SUCCESS) > + efi_warn("efi_random_alloc() failed: 0x%lx\n", status); > + } else { > + status = EFI_OUT_OF_RESOURCES; > + } > + > + if (status != EFI_SUCCESS) { > + if (!check_image_region(*image_addr, kernel_memsize)) { > + efi_err("FIRMWARE BUG: Image BSS overlaps adjacent EFI memory region\n"); > + } else if (IS_ALIGNED(*image_addr, min_kimg_align) && > + (u64)_end < EFI_ALLOC_LIMIT) { > + /* > + * Just execute from wherever we were loaded by the > + * UEFI PE/COFF loader if the placement is suitable. > + */ > + *reserve_size = 0; > + return EFI_SUCCESS; > + } > + > + status = efi_allocate_pages_aligned(*reserve_size, reserve_addr, > + ULONG_MAX, min_kimg_align, > + EFI_LOADER_CODE); > + > + if (status != EFI_SUCCESS) { > + efi_err("Failed to relocate kernel\n"); > + *reserve_size = 0; > + return status; > + } > + } > + > + memcpy((void *)*reserve_addr, (void *)*image_addr, kernel_size); > + *image_addr = *reserve_addr; > + efi_icache_sync(*image_addr, *image_addr + kernel_codesize); > + efi_remap_image(*image_addr, *reserve_size, kernel_codesize); > + > + return status; > +} > -- > 2.39.2 >
diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h index 4cf2cb053bc8..46273ee89445 100644 --- a/arch/arm64/include/asm/efi.h +++ b/arch/arm64/include/asm/efi.h @@ -168,4 +168,6 @@ static inline void efi_capsule_flush_cache_range(void *addr, int size) efi_status_t efi_handle_corrupted_x18(efi_status_t s, const char *f); +void efi_icache_sync(unsigned long start, unsigned long end); + #endif /* _ASM_EFI_H */ diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index 16d64a34d1e1..11aba8a041ec 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -86,7 +86,7 @@ lib-$(CONFIG_EFI_GENERIC_STUB) += efi-stub.o string.o intrinsics.o systable.o \ screen_info.o efi-stub-entry.o lib-$(CONFIG_ARM) += arm32-stub.o -lib-$(CONFIG_ARM64) += arm64.o arm64-stub.o smbios.o +lib-$(CONFIG_ARM64) += kaslr.o arm64.o arm64-stub.o smbios.o lib-$(CONFIG_X86) += x86-stub.o lib-$(CONFIG_RISCV) += riscv.o riscv-stub.o lib-$(CONFIG_LOONGARCH) += loongarch.o loongarch-stub.o diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c index 770b8ecb7398..452b7ccd330e 100644 --- a/drivers/firmware/efi/libstub/arm64-stub.c +++ b/drivers/firmware/efi/libstub/arm64-stub.c @@ -14,42 +14,6 @@ #include "efistub.h" -/* - * Distro versions of GRUB may ignore the BSS allocation entirely (i.e., fail - * to provide space, and fail to zero it). Check for this condition by double - * checking that the first and the last byte of the image are covered by the - * same EFI memory map entry. - */ -static bool check_image_region(u64 base, u64 size) -{ - struct efi_boot_memmap *map; - efi_status_t status; - bool ret = false; - int map_offset; - - status = efi_get_memory_map(&map, false); - if (status != EFI_SUCCESS) - return false; - - for (map_offset = 0; map_offset < map->map_size; map_offset += map->desc_size) { - efi_memory_desc_t *md = (void *)map->map + map_offset; - u64 end = md->phys_addr + md->num_pages * EFI_PAGE_SIZE; - - /* - * Find the region that covers base, and return whether - * it covers base+size bytes. - */ - if (base >= md->phys_addr && base < end) { - ret = (base + size) <= end; - break; - } - } - - efi_bs_call(free_pool, map); - - return ret; -} - efi_status_t handle_kernel_image(unsigned long *image_addr, unsigned long *image_size, unsigned long *reserve_addr, @@ -59,31 +23,6 @@ efi_status_t handle_kernel_image(unsigned long *image_addr, { efi_status_t status; unsigned long kernel_size, kernel_codesize, kernel_memsize; - u32 phys_seed = 0; - u64 min_kimg_align = efi_get_kimg_min_align(); - - if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { - efi_guid_t li_fixed_proto = LINUX_EFI_LOADED_IMAGE_FIXED_GUID; - void *p; - - if (efi_nokaslr) { - efi_info("KASLR disabled on kernel command line\n"); - } else if (efi_bs_call(handle_protocol, image_handle, - &li_fixed_proto, &p) == EFI_SUCCESS) { - efi_info("Image placement fixed by loader\n"); - } else { - status = efi_get_random_bytes(sizeof(phys_seed), - (u8 *)&phys_seed); - if (status == EFI_NOT_FOUND) { - efi_info("EFI_RNG_PROTOCOL unavailable\n"); - efi_nokaslr = true; - } else if (status != EFI_SUCCESS) { - efi_err("efi_get_random_bytes() failed (0x%lx)\n", - status); - efi_nokaslr = true; - } - } - } if (image->image_base != _text) { efi_err("FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value\n"); @@ -98,50 +37,15 @@ efi_status_t handle_kernel_image(unsigned long *image_addr, kernel_codesize = __inittext_end - _text; kernel_memsize = kernel_size + (_end - _edata); *reserve_size = kernel_memsize; + *image_addr = (unsigned long)_text; - if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) { - /* - * If KASLR is enabled, and we have some randomness available, - * locate the kernel at a randomized offset in physical memory. - */ - status = efi_random_alloc(*reserve_size, min_kimg_align, - reserve_addr, phys_seed, - EFI_LOADER_CODE); - if (status != EFI_SUCCESS) - efi_warn("efi_random_alloc() failed: 0x%lx\n", status); - } else { - status = EFI_OUT_OF_RESOURCES; - } - - if (status != EFI_SUCCESS) { - if (!check_image_region((u64)_text, kernel_memsize)) { - efi_err("FIRMWARE BUG: Image BSS overlaps adjacent EFI memory region\n"); - } else if (IS_ALIGNED((u64)_text, min_kimg_align) && - (u64)_end < EFI_ALLOC_LIMIT) { - /* - * Just execute from wherever we were loaded by the - * UEFI PE/COFF loader if the placement is suitable. - */ - *image_addr = (u64)_text; - *reserve_size = 0; - return EFI_SUCCESS; - } - - status = efi_allocate_pages_aligned(*reserve_size, reserve_addr, - ULONG_MAX, min_kimg_align, - EFI_LOADER_CODE); - - if (status != EFI_SUCCESS) { - efi_err("Failed to relocate kernel\n"); - *reserve_size = 0; - return status; - } - } - - *image_addr = *reserve_addr; - memcpy((void *)*image_addr, _text, kernel_size); - caches_clean_inval_pou(*image_addr, *image_addr + kernel_codesize); - efi_remap_image(*image_addr, *reserve_size, kernel_codesize); + status = efi_kaslr_relocate_kernel(image_addr, + reserve_addr, reserve_size, + kernel_size, kernel_codesize, + kernel_memsize, + efi_kaslr_get_phys_seed(image_handle)); + if (status != EFI_SUCCESS) + return status; return EFI_SUCCESS; } @@ -159,3 +63,8 @@ unsigned long primary_entry_offset(void) */ return (char *)primary_entry - _text; } + +void efi_icache_sync(unsigned long start, unsigned long end) +{ + caches_clean_inval_pou(start, end); +} diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h index 6aa38a1bf126..b1a1037567ba 100644 --- a/drivers/firmware/efi/libstub/efistub.h +++ b/drivers/firmware/efi/libstub/efistub.h @@ -1132,6 +1132,14 @@ const u8 *__efi_get_smbios_string(const struct efi_smbios_record *record, void efi_remap_image(unsigned long image_base, unsigned alloc_size, unsigned long code_size); +efi_status_t efi_kaslr_relocate_kernel(unsigned long *image_addr, + unsigned long *reserve_addr, + unsigned long *reserve_size, + unsigned long kernel_size, + unsigned long kernel_codesize, + unsigned long kernel_memsize, + u32 phys_seed); +u32 efi_kaslr_get_phys_seed(efi_handle_t image_handle); asmlinkage efi_status_t __efiapi efi_zboot_entry(efi_handle_t handle, efi_system_table_t *systab); diff --git a/drivers/firmware/efi/libstub/kaslr.c b/drivers/firmware/efi/libstub/kaslr.c new file mode 100644 index 000000000000..be0c8ab0982a --- /dev/null +++ b/drivers/firmware/efi/libstub/kaslr.c @@ -0,0 +1,159 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Helper functions used by the EFI stub on multiple + * architectures to deal with physical address space randomization. + */ +#include <linux/efi.h> + +#include "efistub.h" + +/** + * efi_kaslr_get_phys_seed() - Get random seed for physical kernel KASLR + * @image_handle: Handle to the image + * + * If KASLR is not disabled, obtain a random seed using EFI_RNG_PROTOCOL + * that will be used to move the kernel physical mapping. + * + * Return: the random seed + */ +u32 efi_kaslr_get_phys_seed(efi_handle_t image_handle) +{ + efi_status_t status; + u32 phys_seed; + efi_guid_t li_fixed_proto = LINUX_EFI_LOADED_IMAGE_FIXED_GUID; + void *p; + + if (!IS_ENABLED(CONFIG_RANDOMIZE_BASE)) + return 0; + + if (efi_nokaslr) { + efi_info("KASLR disabled on kernel command line\n"); + } else if (efi_bs_call(handle_protocol, image_handle, + &li_fixed_proto, &p) == EFI_SUCCESS) { + efi_info("Image placement fixed by loader\n"); + } else { + status = efi_get_random_bytes(sizeof(phys_seed), + (u8 *)&phys_seed); + if (status == EFI_SUCCESS) { + return phys_seed; + } else if (status == EFI_NOT_FOUND) { + efi_info("EFI_RNG_PROTOCOL unavailable\n"); + efi_nokaslr = true; + } else if (status != EFI_SUCCESS) { + efi_err("efi_get_random_bytes() failed (0x%lx)\n", + status); + efi_nokaslr = true; + } + } + + return 0; +} + +/* + * Distro versions of GRUB may ignore the BSS allocation entirely (i.e., fail + * to provide space, and fail to zero it). Check for this condition by double + * checking that the first and the last byte of the image are covered by the + * same EFI memory map entry. + */ +static bool check_image_region(u64 base, u64 size) +{ + struct efi_boot_memmap *map; + efi_status_t status; + bool ret = false; + int map_offset; + + status = efi_get_memory_map(&map, false); + if (status != EFI_SUCCESS) + return false; + + for (map_offset = 0; map_offset < map->map_size; map_offset += map->desc_size) { + efi_memory_desc_t *md = (void *)map->map + map_offset; + u64 end = md->phys_addr + md->num_pages * EFI_PAGE_SIZE; + + /* + * Find the region that covers base, and return whether + * it covers base+size bytes. + */ + if (base >= md->phys_addr && base < end) { + ret = (base + size) <= end; + break; + } + } + + efi_bs_call(free_pool, map); + + return ret; +} + +/** + * efi_kaslr_relocate_kernel() - Relocate the kernel (random if KASLR enabled) + * @image_addr: Pointer to the current kernel location + * @reserve_addr: Pointer to the relocated kernel location + * @reserve_size: Size of the relocated kernel + * @kernel_size: Size of the text + data + * @kernel_codesize: Size of the text + * @kernel_memsize: Size of the text + data + bss + * @phys_seed: Random seed used for the relocation + * + * If KASLR is not enabled, this function relocates the kernel to a fixed + * address (or leave it as its current location). If KASLR is enabled, the + * kernel physical location is randomized using the seed in parameter. + * + * Return: status code, EFI_SUCCESS if relocation is successful + */ +efi_status_t efi_kaslr_relocate_kernel(unsigned long *image_addr, + unsigned long *reserve_addr, + unsigned long *reserve_size, + unsigned long kernel_size, + unsigned long kernel_codesize, + unsigned long kernel_memsize, + u32 phys_seed) +{ + efi_status_t status; + u64 min_kimg_align = efi_get_kimg_min_align(); + + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) { + /* + * If KASLR is enabled, and we have some randomness available, + * locate the kernel at a randomized offset in physical memory. + */ + status = efi_random_alloc(*reserve_size, min_kimg_align, + reserve_addr, phys_seed, + EFI_LOADER_CODE); + if (status != EFI_SUCCESS) + efi_warn("efi_random_alloc() failed: 0x%lx\n", status); + } else { + status = EFI_OUT_OF_RESOURCES; + } + + if (status != EFI_SUCCESS) { + if (!check_image_region(*image_addr, kernel_memsize)) { + efi_err("FIRMWARE BUG: Image BSS overlaps adjacent EFI memory region\n"); + } else if (IS_ALIGNED(*image_addr, min_kimg_align) && + (u64)_end < EFI_ALLOC_LIMIT) { + /* + * Just execute from wherever we were loaded by the + * UEFI PE/COFF loader if the placement is suitable. + */ + *reserve_size = 0; + return EFI_SUCCESS; + } + + status = efi_allocate_pages_aligned(*reserve_size, reserve_addr, + ULONG_MAX, min_kimg_align, + EFI_LOADER_CODE); + + if (status != EFI_SUCCESS) { + efi_err("Failed to relocate kernel\n"); + *reserve_size = 0; + return status; + } + } + + memcpy((void *)*reserve_addr, (void *)*image_addr, kernel_size); + *image_addr = *reserve_addr; + efi_icache_sync(*image_addr, *image_addr + kernel_codesize); + efi_remap_image(*image_addr, *reserve_size, kernel_codesize); + + return status; +}
This prepares for riscv to use the same functions to handle the pĥysical kernel move when KASLR is enabled. Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> --- arch/arm64/include/asm/efi.h | 2 + drivers/firmware/efi/libstub/Makefile | 2 +- drivers/firmware/efi/libstub/arm64-stub.c | 117 ++-------------- drivers/firmware/efi/libstub/efistub.h | 8 ++ drivers/firmware/efi/libstub/kaslr.c | 159 ++++++++++++++++++++++ 5 files changed, 183 insertions(+), 105 deletions(-) create mode 100644 drivers/firmware/efi/libstub/kaslr.c