* [PATCH v4 0/5] riscv: Introduce KASLR
@ 2023-07-13 13:33 Alexandre Ghiti
2023-07-13 13:33 ` [PATCH v4 1/5] riscv: Introduce virtual kernel mapping KASLR Alexandre Ghiti
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Alexandre Ghiti @ 2023-07-13 13:33 UTC (permalink / raw)
To: Paul Walmsley, Palmer Dabbelt, Albert Ou, Ard Biesheuvel,
linux-riscv, linux-kernel, linux-efi, linux-arm-kernel
Cc: Alexandre Ghiti
The following KASLR implementation allows to randomize the kernel mapping:
- virtually: we expect the bootloader to provide a seed in the device-tree
- physically: only implemented in the EFI stub, it relies on the firmware to
provide a seed using EFI_RNG_PROTOCOL. arm64 has a similar implementation
hence the patch 3 factorizes KASLR related functions for riscv to take
advantage.
The new virtual kernel location is limited by the early page table that only
has one PUD and with the PMD alignment constraint, the kernel can only take
< 512 positions.
base-commit-tag: v6.5-rc1
Changes in v4:
* Fix efi_get_kimg macro that returned nothing
* Moved new kaslr functions into their own files to avoid zboot link
failures, as suggested by Ard
Changes in v3:
* Rebase on top of 6.4-rc2
* Make RANDOMIZE_BASE depend on 64bit
* Fix efi_icache_sync and efi_get_kimg_min_align which were undefined
in x86 (and certainly other archs)
* Add patch 4 to fix warning on rv32
Changes in v2:
* Rebase on top of 6.3-rc1
* Add a riscv cache sync after memcpying the kernel
* Add kaslr_offset implementation for KCOV
* Add forward declaration to quiet LLVM
Alexandre Ghiti (5):
riscv: Introduce virtual kernel mapping KASLR
riscv: Dump out kernel offset information on panic
arm64: libstub: Move KASLR handling functions to efi-stub-helper.c
libstub: Fix compilation warning for rv32
riscv: libstub: Implement KASLR by using generic functions
arch/arm64/include/asm/efi.h | 4 +
arch/riscv/Kconfig | 19 +++
arch/riscv/include/asm/efi.h | 4 +
arch/riscv/include/asm/page.h | 3 +
arch/riscv/kernel/image-vars.h | 1 +
arch/riscv/kernel/pi/Makefile | 2 +-
arch/riscv/kernel/pi/cmdline_early.c | 13 ++
arch/riscv/kernel/pi/fdt_early.c | 30 ++++
arch/riscv/kernel/setup.c | 25 +++
arch/riscv/mm/init.c | 36 +++-
drivers/firmware/efi/libstub/Makefile | 3 +-
drivers/firmware/efi/libstub/arm64-stub.c | 117 ++-----------
drivers/firmware/efi/libstub/efi-stub-kaslr.c | 159 ++++++++++++++++++
drivers/firmware/efi/libstub/efistub.h | 18 ++
drivers/firmware/efi/libstub/riscv-stub.c | 33 ++--
15 files changed, 342 insertions(+), 125 deletions(-)
create mode 100644 arch/riscv/kernel/pi/fdt_early.c
create mode 100644 drivers/firmware/efi/libstub/efi-stub-kaslr.c
--
2.39.2
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^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v4 1/5] riscv: Introduce virtual kernel mapping KASLR
2023-07-13 13:33 [PATCH v4 0/5] riscv: Introduce KASLR Alexandre Ghiti
@ 2023-07-13 13:33 ` Alexandre Ghiti
2023-07-13 13:33 ` [PATCH v4 2/5] riscv: Dump out kernel offset information on panic Alexandre Ghiti
2023-07-13 13:33 ` [PATCH v4 3/5] arm64: libstub: Move KASLR handling functions to efi-stub-helper.c Alexandre Ghiti
2 siblings, 0 replies; 6+ messages in thread
From: Alexandre Ghiti @ 2023-07-13 13:33 UTC (permalink / raw)
To: Paul Walmsley, Palmer Dabbelt, Albert Ou, Ard Biesheuvel,
linux-riscv, linux-kernel, linux-efi, linux-arm-kernel
Cc: Alexandre Ghiti
KASLR implementation relies on a relocatable kernel so that we can move
the kernel mapping.
The seed needed to virtually move the kernel is taken from the device tree,
so we rely on the bootloader to provide a correct seed. Zkr could be used
unconditionnally instead if implemented, but that's for another patch.
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---
arch/riscv/Kconfig | 19 +++++++++++++++
arch/riscv/include/asm/page.h | 3 +++
arch/riscv/kernel/pi/Makefile | 2 +-
arch/riscv/kernel/pi/cmdline_early.c | 13 ++++++++++
arch/riscv/kernel/pi/fdt_early.c | 30 +++++++++++++++++++++++
arch/riscv/mm/init.c | 36 +++++++++++++++++++++++++++-
6 files changed, 101 insertions(+), 2 deletions(-)
create mode 100644 arch/riscv/kernel/pi/fdt_early.c
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 4c07b9189c86..6a606d5b74c6 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -719,6 +719,25 @@ config RELOCATABLE
If unsure, say N.
+config RANDOMIZE_BASE
+ bool "Randomize the address of the kernel image"
+ select RELOCATABLE
+ depends on MMU && 64BIT && !XIP_KERNEL
+ help
+ Randomizes the virtual address at which the kernel image is
+ loaded, as a security feature that deters exploit attempts
+ relying on knowledge of the location of kernel internals.
+
+ It is the bootloader's job to provide entropy, by passing a
+ random u64 value in /chosen/kaslr-seed at kernel entry.
+
+ When booting via the UEFI stub, it will invoke the firmware's
+ EFI_RNG_PROTOCOL implementation (if available) to supply entropy
+ to the kernel proper. In addition, it will randomise the physical
+ location of the kernel Image as well.
+
+ If unsure, say N.
+
endmenu # "Kernel features"
menu "Boot options"
diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
index b55ba20903ec..5488ecc337b6 100644
--- a/arch/riscv/include/asm/page.h
+++ b/arch/riscv/include/asm/page.h
@@ -106,6 +106,7 @@ typedef struct page *pgtable_t;
struct kernel_mapping {
unsigned long page_offset;
unsigned long virt_addr;
+ unsigned long virt_offset;
uintptr_t phys_addr;
uintptr_t size;
/* Offset between linear mapping virtual address and kernel load address */
@@ -185,6 +186,8 @@ extern phys_addr_t __phys_addr_symbol(unsigned long x);
#define sym_to_pfn(x) __phys_to_pfn(__pa_symbol(x))
+unsigned long kaslr_offset(void);
+
#endif /* __ASSEMBLY__ */
#define virt_addr_valid(vaddr) ({ \
diff --git a/arch/riscv/kernel/pi/Makefile b/arch/riscv/kernel/pi/Makefile
index 7b593d44c712..07915dc9279e 100644
--- a/arch/riscv/kernel/pi/Makefile
+++ b/arch/riscv/kernel/pi/Makefile
@@ -35,5 +35,5 @@ $(obj)/string.o: $(srctree)/lib/string.c FORCE
$(obj)/ctype.o: $(srctree)/lib/ctype.c FORCE
$(call if_changed_rule,cc_o_c)
-obj-y := cmdline_early.pi.o string.pi.o ctype.pi.o lib-fdt.pi.o lib-fdt_ro.pi.o
+obj-y := cmdline_early.pi.o fdt_early.pi.o string.pi.o ctype.pi.o lib-fdt.pi.o lib-fdt_ro.pi.o
extra-y := $(patsubst %.pi.o,%.o,$(obj-y))
diff --git a/arch/riscv/kernel/pi/cmdline_early.c b/arch/riscv/kernel/pi/cmdline_early.c
index 05652d13c746..68e786c84c94 100644
--- a/arch/riscv/kernel/pi/cmdline_early.c
+++ b/arch/riscv/kernel/pi/cmdline_early.c
@@ -14,6 +14,7 @@ static char early_cmdline[COMMAND_LINE_SIZE];
* LLVM complain because the function is actually unused in this file).
*/
u64 set_satp_mode_from_cmdline(uintptr_t dtb_pa);
+bool set_nokaslr_from_cmdline(uintptr_t dtb_pa);
static char *get_early_cmdline(uintptr_t dtb_pa)
{
@@ -60,3 +61,15 @@ u64 set_satp_mode_from_cmdline(uintptr_t dtb_pa)
return match_noXlvl(cmdline);
}
+
+static bool match_nokaslr(char *cmdline)
+{
+ return strstr(cmdline, "nokaslr");
+}
+
+bool set_nokaslr_from_cmdline(uintptr_t dtb_pa)
+{
+ char *cmdline = get_early_cmdline(dtb_pa);
+
+ return match_nokaslr(cmdline);
+}
diff --git a/arch/riscv/kernel/pi/fdt_early.c b/arch/riscv/kernel/pi/fdt_early.c
new file mode 100644
index 000000000000..899610e042ab
--- /dev/null
+++ b/arch/riscv/kernel/pi/fdt_early.c
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/libfdt.h>
+
+/*
+ * Declare the functions that are exported (but prefixed) here so that LLVM
+ * does not complain it lacks the 'static' keyword (which, if added, makes
+ * LLVM complain because the function is actually unused in this file).
+ */
+u64 get_kaslr_seed(uintptr_t dtb_pa);
+
+u64 get_kaslr_seed(uintptr_t dtb_pa)
+{
+ int node, len;
+ fdt64_t *prop;
+ u64 ret;
+
+ node = fdt_path_offset((void *)dtb_pa, "/chosen");
+ if (node < 0)
+ return 0;
+
+ prop = fdt_getprop_w((void *)dtb_pa, node, "kaslr-seed", &len);
+ if (!prop || len != sizeof(u64))
+ return 0;
+
+ ret = fdt64_to_cpu(*prop);
+ *prop = 0;
+ return ret;
+}
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 70fb31960b63..ff926531236e 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -1012,11 +1012,45 @@ static void __init pt_ops_set_late(void)
#endif
}
+#ifdef CONFIG_RANDOMIZE_BASE
+extern bool __init __pi_set_nokaslr_from_cmdline(uintptr_t dtb_pa);
+extern u64 __init __pi_get_kaslr_seed(uintptr_t dtb_pa);
+
+static int __init print_nokaslr(char *p)
+{
+ pr_info("Disabled KASLR");
+ return 0;
+}
+early_param("nokaslr", print_nokaslr);
+
+unsigned long kaslr_offset(void)
+{
+ return kernel_map.virt_offset;
+}
+#endif
+
asmlinkage void __init setup_vm(uintptr_t dtb_pa)
{
pmd_t __maybe_unused fix_bmap_spmd, fix_bmap_epmd;
- kernel_map.virt_addr = KERNEL_LINK_ADDR;
+#ifdef CONFIG_RANDOMIZE_BASE
+ if (!__pi_set_nokaslr_from_cmdline(dtb_pa)) {
+ u64 kaslr_seed = __pi_get_kaslr_seed(dtb_pa);
+ u32 kernel_size = (uintptr_t)(&_end) - (uintptr_t)(&_start);
+ u32 nr_pos;
+
+ /*
+ * Compute the number of positions available: we are limited
+ * by the early page table that only has one PUD and we must
+ * be aligned on PMD_SIZE.
+ */
+ nr_pos = (PUD_SIZE - kernel_size) / PMD_SIZE;
+
+ kernel_map.virt_offset = (kaslr_seed % nr_pos) * PMD_SIZE;
+ }
+#endif
+
+ kernel_map.virt_addr = KERNEL_LINK_ADDR + kernel_map.virt_offset;
kernel_map.page_offset = _AC(CONFIG_PAGE_OFFSET, UL);
#ifdef CONFIG_XIP_KERNEL
--
2.39.2
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linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH v4 2/5] riscv: Dump out kernel offset information on panic
2023-07-13 13:33 [PATCH v4 0/5] riscv: Introduce KASLR Alexandre Ghiti
2023-07-13 13:33 ` [PATCH v4 1/5] riscv: Introduce virtual kernel mapping KASLR Alexandre Ghiti
@ 2023-07-13 13:33 ` Alexandre Ghiti
2023-07-13 13:33 ` [PATCH v4 3/5] arm64: libstub: Move KASLR handling functions to efi-stub-helper.c Alexandre Ghiti
2 siblings, 0 replies; 6+ messages in thread
From: Alexandre Ghiti @ 2023-07-13 13:33 UTC (permalink / raw)
To: Paul Walmsley, Palmer Dabbelt, Albert Ou, Ard Biesheuvel,
linux-riscv, linux-kernel, linux-efi, linux-arm-kernel
Cc: Alexandre Ghiti, Zong Li
Dump out the KASLR virtual kernel offset when panic to help debug kernel.
Signed-off-by: Zong Li <zong.li@sifive.com>
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---
arch/riscv/kernel/setup.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index 971fe776e2f8..0fb5a26ca4cc 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -21,6 +21,7 @@
#include <linux/smp.h>
#include <linux/efi.h>
#include <linux/crash_dump.h>
+#include <linux/panic_notifier.h>
#include <asm/acpi.h>
#include <asm/alternative.h>
@@ -341,3 +342,27 @@ void free_initmem(void)
free_initmem_default(POISON_FREE_INITMEM);
}
+
+static int dump_kernel_offset(struct notifier_block *self,
+ unsigned long v, void *p)
+{
+ pr_emerg("Kernel Offset: 0x%lx from 0x%lx\n",
+ kernel_map.virt_offset,
+ KERNEL_LINK_ADDR);
+
+ return 0;
+}
+
+static struct notifier_block kernel_offset_notifier = {
+ .notifier_call = dump_kernel_offset
+};
+
+static int __init register_kernel_offset_dumper(void)
+{
+ if (IS_ENABLED(CONFIG_RANDOMIZE_BASE))
+ atomic_notifier_chain_register(&panic_notifier_list,
+ &kernel_offset_notifier);
+
+ return 0;
+}
+device_initcall(register_kernel_offset_dumper);
--
2.39.2
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linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH v4 3/5] arm64: libstub: Move KASLR handling functions to efi-stub-helper.c
2023-07-13 13:33 [PATCH v4 0/5] riscv: Introduce KASLR Alexandre Ghiti
2023-07-13 13:33 ` [PATCH v4 1/5] riscv: Introduce virtual kernel mapping KASLR Alexandre Ghiti
2023-07-13 13:33 ` [PATCH v4 2/5] riscv: Dump out kernel offset information on panic Alexandre Ghiti
@ 2023-07-13 13:33 ` Alexandre Ghiti
2023-07-13 14:30 ` Ard Biesheuvel
2 siblings, 1 reply; 6+ messages in thread
From: Alexandre Ghiti @ 2023-07-13 13:33 UTC (permalink / raw)
To: Paul Walmsley, Palmer Dabbelt, Albert Ou, Ard Biesheuvel,
linux-riscv, linux-kernel, linux-efi, linux-arm-kernel
Cc: Alexandre Ghiti
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 | 4 +
arch/riscv/include/asm/efi.h | 1 +
drivers/firmware/efi/libstub/Makefile | 3 +-
drivers/firmware/efi/libstub/arm64-stub.c | 117 ++-----------
drivers/firmware/efi/libstub/efi-stub-kaslr.c | 159 ++++++++++++++++++
drivers/firmware/efi/libstub/efistub.h | 18 ++
6 files changed, 197 insertions(+), 105 deletions(-)
create mode 100644 drivers/firmware/efi/libstub/efi-stub-kaslr.c
diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
index 4cf2cb053bc8..83a4d69fd968 100644
--- a/arch/arm64/include/asm/efi.h
+++ b/arch/arm64/include/asm/efi.h
@@ -111,6 +111,7 @@ static inline unsigned long efi_get_kimg_min_align(void)
*/
return efi_nokaslr ? MIN_KIMG_ALIGN : EFI_KIMG_ALIGN;
}
+#define efi_get_kimg_min_align efi_get_kimg_min_align
#define EFI_ALLOC_ALIGN SZ_64K
#define EFI_ALLOC_LIMIT ((1UL << 48) - 1)
@@ -168,4 +169,7 @@ 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);
+#define efi_icache_sync efi_icache_sync
+
#endif /* _ASM_EFI_H */
diff --git a/arch/riscv/include/asm/efi.h b/arch/riscv/include/asm/efi.h
index 29e9a0d84b16..c3dafaab36a2 100644
--- a/arch/riscv/include/asm/efi.h
+++ b/arch/riscv/include/asm/efi.h
@@ -43,6 +43,7 @@ static inline unsigned long efi_get_kimg_min_align(void)
*/
return IS_ENABLED(CONFIG_64BIT) ? SZ_2M : SZ_4M;
}
+#define efi_get_kimg_min_align efi_get_kimg_min_align
#define EFI_KIMG_PREFERRED_ADDRESS efi_get_kimg_min_align()
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index 16d64a34d1e1..5927fab5c834 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -67,7 +67,8 @@ OBJECT_FILES_NON_STANDARD := y
# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
KCOV_INSTRUMENT := n
-lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o \
+lib-y := efi-stub-helper.o efi-stub-kaslr.o \
+ gop.o secureboot.o tpm.o \
file.o mem.o random.o randomalloc.o pci.o \
skip_spaces.o lib-cmdline.o lib-ctype.o \
alignedmem.o relocate.o printk.o vsprintf.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/efi-stub-kaslr.c b/drivers/firmware/efi/libstub/efi-stub-kaslr.c
new file mode 100644
index 000000000000..be0c8ab0982a
--- /dev/null
+++ b/drivers/firmware/efi/libstub/efi-stub-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;
+}
diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index 6aa38a1bf126..35337ea5056e 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -1132,6 +1132,24 @@ 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);
+
+#ifndef efi_get_kimg_min_align
+static inline unsigned long efi_get_kimg_min_align(void) { return 0; }
+#define efi_get_kimg_min_align efi_get_kimg_min_align
+#endif
+
+#ifndef efi_icache_sync
+static inline void efi_icache_sync(unsigned long start, unsigned long end) {}
+#define efi_icache_sync efi_icache_sync
+#endif
asmlinkage efi_status_t __efiapi
efi_zboot_entry(efi_handle_t handle, efi_system_table_t *systab);
--
2.39.2
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^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v4 3/5] arm64: libstub: Move KASLR handling functions to efi-stub-helper.c
2023-07-13 13:33 ` [PATCH v4 3/5] arm64: libstub: Move KASLR handling functions to efi-stub-helper.c Alexandre Ghiti
@ 2023-07-13 14:30 ` Ard Biesheuvel
2023-07-13 15:06 ` Alexandre Ghiti
0 siblings, 1 reply; 6+ messages in thread
From: Ard Biesheuvel @ 2023-07-13 14:30 UTC (permalink / raw)
To: Alexandre Ghiti
Cc: Paul Walmsley, Palmer Dabbelt, Albert Ou, linux-riscv,
linux-kernel, linux-efi, linux-arm-kernel
Hello Alexandre,
On Thu, 13 Jul 2023 at 15:37, 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>
> ---
> arch/arm64/include/asm/efi.h | 4 +
> arch/riscv/include/asm/efi.h | 1 +
> drivers/firmware/efi/libstub/Makefile | 3 +-
> drivers/firmware/efi/libstub/arm64-stub.c | 117 ++-----------
> drivers/firmware/efi/libstub/efi-stub-kaslr.c | 159 ++++++++++++++++++
Please just call the file kaslr.c
> drivers/firmware/efi/libstub/efistub.h | 18 ++
> 6 files changed, 197 insertions(+), 105 deletions(-)
> create mode 100644 drivers/firmware/efi/libstub/efi-stub-kaslr.c
>
> diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
> index 4cf2cb053bc8..83a4d69fd968 100644
> --- a/arch/arm64/include/asm/efi.h
> +++ b/arch/arm64/include/asm/efi.h
> @@ -111,6 +111,7 @@ static inline unsigned long efi_get_kimg_min_align(void)
> */
> return efi_nokaslr ? MIN_KIMG_ALIGN : EFI_KIMG_ALIGN;
> }
> +#define efi_get_kimg_min_align efi_get_kimg_min_align
>
> #define EFI_ALLOC_ALIGN SZ_64K
> #define EFI_ALLOC_LIMIT ((1UL << 48) - 1)
> @@ -168,4 +169,7 @@ 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);
> +#define efi_icache_sync efi_icache_sync
> +
Given that arm64 is the only arch that needs to implement this, can we
just keep the call in arch code? I.e., after
efi_kaslr_relocate_kernel() if it returned with EFI_SUCCESS?
> #endif /* _ASM_EFI_H */
> diff --git a/arch/riscv/include/asm/efi.h b/arch/riscv/include/asm/efi.h
> index 29e9a0d84b16..c3dafaab36a2 100644
> --- a/arch/riscv/include/asm/efi.h
> +++ b/arch/riscv/include/asm/efi.h
> @@ -43,6 +43,7 @@ static inline unsigned long efi_get_kimg_min_align(void)
> */
> return IS_ENABLED(CONFIG_64BIT) ? SZ_2M : SZ_4M;
> }
> +#define efi_get_kimg_min_align efi_get_kimg_min_align
>
> #define EFI_KIMG_PREFERRED_ADDRESS efi_get_kimg_min_align()
>
> diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
> index 16d64a34d1e1..5927fab5c834 100644
> --- a/drivers/firmware/efi/libstub/Makefile
> +++ b/drivers/firmware/efi/libstub/Makefile
> @@ -67,7 +67,8 @@ OBJECT_FILES_NON_STANDARD := y
> # Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
> KCOV_INSTRUMENT := n
>
> -lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o \
> +lib-y := efi-stub-helper.o efi-stub-kaslr.o \
> + gop.o secureboot.o tpm.o \
> file.o mem.o random.o randomalloc.o pci.o \
> skip_spaces.o lib-cmdline.o lib-ctype.o \
> alignedmem.o relocate.o printk.o vsprintf.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/efi-stub-kaslr.c b/drivers/firmware/efi/libstub/efi-stub-kaslr.c
> new file mode 100644
> index 000000000000..be0c8ab0982a
> --- /dev/null
> +++ b/drivers/firmware/efi/libstub/efi-stub-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;
> +}
> diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
> index 6aa38a1bf126..35337ea5056e 100644
> --- a/drivers/firmware/efi/libstub/efistub.h
> +++ b/drivers/firmware/efi/libstub/efistub.h
> @@ -1132,6 +1132,24 @@ 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);
> +
> +#ifndef efi_get_kimg_min_align
> +static inline unsigned long efi_get_kimg_min_align(void) { return 0; }
Shouldn't this be EFI_PAGE_SIZE at least? Surely, the RISC-V kernel
image has some minimal alignment?
> +#define efi_get_kimg_min_align efi_get_kimg_min_align
> +#endif
> +
> +#ifndef efi_icache_sync
> +static inline void efi_icache_sync(unsigned long start, unsigned long end) {}
> +#define efi_icache_sync efi_icache_sync
> +#endif
>
> asmlinkage efi_status_t __efiapi
> efi_zboot_entry(efi_handle_t handle, efi_system_table_t *systab);
> --
> 2.39.2
>
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v4 3/5] arm64: libstub: Move KASLR handling functions to efi-stub-helper.c
2023-07-13 14:30 ` Ard Biesheuvel
@ 2023-07-13 15:06 ` Alexandre Ghiti
0 siblings, 0 replies; 6+ messages in thread
From: Alexandre Ghiti @ 2023-07-13 15:06 UTC (permalink / raw)
To: Ard Biesheuvel
Cc: Paul Walmsley, Palmer Dabbelt, Albert Ou, linux-riscv,
linux-kernel, linux-efi, linux-arm-kernel
Hi Ard,
On Thu, Jul 13, 2023 at 4:30 PM Ard Biesheuvel <ardb@kernel.org> wrote:
>
> Hello Alexandre,
>
> On Thu, 13 Jul 2023 at 15:37, 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>
> > ---
> > arch/arm64/include/asm/efi.h | 4 +
> > arch/riscv/include/asm/efi.h | 1 +
> > drivers/firmware/efi/libstub/Makefile | 3 +-
> > drivers/firmware/efi/libstub/arm64-stub.c | 117 ++-----------
> > drivers/firmware/efi/libstub/efi-stub-kaslr.c | 159 ++++++++++++++++++
>
> Please just call the file kaslr.c
Ok
>
> > drivers/firmware/efi/libstub/efistub.h | 18 ++
> > 6 files changed, 197 insertions(+), 105 deletions(-)
> > create mode 100644 drivers/firmware/efi/libstub/efi-stub-kaslr.c
> >
> > diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
> > index 4cf2cb053bc8..83a4d69fd968 100644
> > --- a/arch/arm64/include/asm/efi.h
> > +++ b/arch/arm64/include/asm/efi.h
> > @@ -111,6 +111,7 @@ static inline unsigned long efi_get_kimg_min_align(void)
> > */
> > return efi_nokaslr ? MIN_KIMG_ALIGN : EFI_KIMG_ALIGN;
> > }
> > +#define efi_get_kimg_min_align efi_get_kimg_min_align
> >
> > #define EFI_ALLOC_ALIGN SZ_64K
> > #define EFI_ALLOC_LIMIT ((1UL << 48) - 1)
> > @@ -168,4 +169,7 @@ 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);
> > +#define efi_icache_sync efi_icache_sync
> > +
>
> Given that arm64 is the only arch that needs to implement this, can we
> just keep the call in arch code? I.e., after
> efi_kaslr_relocate_kernel() if it returned with EFI_SUCCESS?
Actually, I implement this function for riscv in patch 5 as we need to
sync the icache and the dcache too. But my flaky internet did not
survive long enough.
>
>
> > #endif /* _ASM_EFI_H */
> > diff --git a/arch/riscv/include/asm/efi.h b/arch/riscv/include/asm/efi.h
> > index 29e9a0d84b16..c3dafaab36a2 100644
> > --- a/arch/riscv/include/asm/efi.h
> > +++ b/arch/riscv/include/asm/efi.h
> > @@ -43,6 +43,7 @@ static inline unsigned long efi_get_kimg_min_align(void)
> > */
> > return IS_ENABLED(CONFIG_64BIT) ? SZ_2M : SZ_4M;
> > }
> > +#define efi_get_kimg_min_align efi_get_kimg_min_align
efi_get_kimg_min_align() is implemented here for riscv ^
> >
> > #define EFI_KIMG_PREFERRED_ADDRESS efi_get_kimg_min_align()
> >
> > diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
> > index 16d64a34d1e1..5927fab5c834 100644
> > --- a/drivers/firmware/efi/libstub/Makefile
> > +++ b/drivers/firmware/efi/libstub/Makefile
> > @@ -67,7 +67,8 @@ OBJECT_FILES_NON_STANDARD := y
> > # Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
> > KCOV_INSTRUMENT := n
> >
> > -lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o \
> > +lib-y := efi-stub-helper.o efi-stub-kaslr.o \
> > + gop.o secureboot.o tpm.o \
> > file.o mem.o random.o randomalloc.o pci.o \
> > skip_spaces.o lib-cmdline.o lib-ctype.o \
> > alignedmem.o relocate.o printk.o vsprintf.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/efi-stub-kaslr.c b/drivers/firmware/efi/libstub/efi-stub-kaslr.c
> > new file mode 100644
> > index 000000000000..be0c8ab0982a
> > --- /dev/null
> > +++ b/drivers/firmware/efi/libstub/efi-stub-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;
> > +}
> > diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
> > index 6aa38a1bf126..35337ea5056e 100644
> > --- a/drivers/firmware/efi/libstub/efistub.h
> > +++ b/drivers/firmware/efi/libstub/efistub.h
> > @@ -1132,6 +1132,24 @@ 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);
> > +
> > +#ifndef efi_get_kimg_min_align
> > +static inline unsigned long efi_get_kimg_min_align(void) { return 0; }
>
> Shouldn't this be EFI_PAGE_SIZE at least? Surely, the RISC-V kernel
> image has some minimal alignment?
efi_get_kimg_min_align() is implemented above for riscv, this stub is
here to prevent build failures for other architectures that do not
define it (ie x86). But actually, since I have moved the new functions
to their own file, I'm not sure I still need those stubs, I'll check
and remove them in v5 if possible.
>
>
> > +#define efi_get_kimg_min_align efi_get_kimg_min_align
> > +#endif
> > +
> > +#ifndef efi_icache_sync
> > +static inline void efi_icache_sync(unsigned long start, unsigned long end) {}
> > +#define efi_icache_sync efi_icache_sync
> > +#endif
> >
> > asmlinkage efi_status_t __efiapi
> > efi_zboot_entry(efi_handle_t handle, efi_system_table_t *systab);
> > --
> > 2.39.2
> >
Thanks, and sorry for the truncated series, I'll resend this version
for everyone to have a look at the next 2 patches but keep in mind
your feedback for v5.
Alex
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^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2023-07-13 15:06 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-07-13 13:33 [PATCH v4 0/5] riscv: Introduce KASLR Alexandre Ghiti
2023-07-13 13:33 ` [PATCH v4 1/5] riscv: Introduce virtual kernel mapping KASLR Alexandre Ghiti
2023-07-13 13:33 ` [PATCH v4 2/5] riscv: Dump out kernel offset information on panic Alexandre Ghiti
2023-07-13 13:33 ` [PATCH v4 3/5] arm64: libstub: Move KASLR handling functions to efi-stub-helper.c Alexandre Ghiti
2023-07-13 14:30 ` Ard Biesheuvel
2023-07-13 15:06 ` Alexandre Ghiti
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