diff options
Diffstat (limited to 'arch')
-rw-r--r-- | arch/x86/boot/compressed/kaslr.c | 41 | ||||
-rw-r--r-- | arch/x86/boot/compressed/misc.c | 49 | ||||
-rw-r--r-- | arch/x86/boot/compressed/misc.h | 22 |
3 files changed, 64 insertions, 48 deletions
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c index 54037c9f2def..5550546916be 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -463,17 +463,20 @@ static unsigned long find_random_virt_addr(unsigned long minimum, * Since this function examines addresses much more numerically, * it takes the input and output pointers as 'unsigned long'. */ -unsigned char *choose_random_location(unsigned long input, - unsigned long input_size, - unsigned long output, - unsigned long output_size) +void choose_random_location(unsigned long input, + unsigned long input_size, + unsigned long *output, + unsigned long output_size, + unsigned long *virt_addr) { - unsigned long choice = output; unsigned long random_addr; + /* By default, keep output position unchanged. */ + *virt_addr = *output; + if (cmdline_find_option_bool("nokaslr")) { warn("KASLR disabled: 'nokaslr' on cmdline."); - goto out; + return; } boot_params->hdr.loadflags |= KASLR_FLAG; @@ -482,25 +485,25 @@ unsigned char *choose_random_location(unsigned long input, initialize_identity_maps(); /* Record the various known unsafe memory ranges. */ - mem_avoid_init(input, input_size, output); + mem_avoid_init(input, input_size, *output); /* Walk e820 and find a random address. */ - random_addr = find_random_phys_addr(output, output_size); + random_addr = find_random_phys_addr(*output, output_size); if (!random_addr) { warn("KASLR disabled: could not find suitable E820 region!"); - goto out; + } else { + /* Update the new physical address location. */ + if (*output != random_addr) { + add_identity_map(random_addr, output_size); + *output = random_addr; + } } - /* Always enforce the minimum. */ - if (random_addr < choice) - goto out; - - choice = random_addr; - - add_identity_map(choice, output_size); - /* This actually loads the identity pagetable on x86_64. */ finalize_identity_maps(); -out: - return (unsigned char *)choice; + + /* Pick random virtual address starting from LOAD_PHYSICAL_ADDR. */ + if (IS_ENABLED(CONFIG_X86_64)) + random_addr = find_random_virt_addr(LOAD_PHYSICAL_ADDR, output_size); + *virt_addr = random_addr; } diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c index f14db4e21654..b3c5a5f030ce 100644 --- a/arch/x86/boot/compressed/misc.c +++ b/arch/x86/boot/compressed/misc.c @@ -170,7 +170,8 @@ void __puthex(unsigned long value) } #if CONFIG_X86_NEED_RELOCS -static void handle_relocations(void *output, unsigned long output_len) +static void handle_relocations(void *output, unsigned long output_len, + unsigned long virt_addr) { int *reloc; unsigned long delta, map, ptr; @@ -182,11 +183,6 @@ static void handle_relocations(void *output, unsigned long output_len) * and where it was actually loaded. */ delta = min_addr - LOAD_PHYSICAL_ADDR; - if (!delta) { - debug_putstr("No relocation needed... "); - return; - } - debug_putstr("Performing relocations... "); /* * The kernel contains a table of relocation addresses. Those @@ -198,6 +194,20 @@ static void handle_relocations(void *output, unsigned long output_len) map = delta - __START_KERNEL_map; /* + * 32-bit always performs relocations. 64-bit relocations are only + * needed if KASLR has chosen a different starting address offset + * from __START_KERNEL_map. + */ + if (IS_ENABLED(CONFIG_X86_64)) + delta = virt_addr - LOAD_PHYSICAL_ADDR; + + if (!delta) { + debug_putstr("No relocation needed... "); + return; + } + debug_putstr("Performing relocations... "); + + /* * Process relocations: 32 bit relocations first then 64 bit after. * Three sets of binary relocations are added to the end of the kernel * before compression. Each relocation table entry is the kernel @@ -250,7 +260,8 @@ static void handle_relocations(void *output, unsigned long output_len) #endif } #else -static inline void handle_relocations(void *output, unsigned long output_len) +static inline void handle_relocations(void *output, unsigned long output_len, + unsigned long virt_addr) { } #endif @@ -327,7 +338,7 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, unsigned long output_len) { const unsigned long kernel_total_size = VO__end - VO__text; - unsigned char *output_orig = output; + unsigned long virt_addr = (unsigned long)output; /* Retain x86 boot parameters pointer passed from startup_32/64. */ boot_params = rmode; @@ -366,13 +377,16 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, * the entire decompressed kernel plus relocation table, or the * entire decompressed kernel plus .bss and .brk sections. */ - output = choose_random_location((unsigned long)input_data, input_len, - (unsigned long)output, - max(output_len, kernel_total_size)); + choose_random_location((unsigned long)input_data, input_len, + (unsigned long *)&output, + max(output_len, kernel_total_size), + &virt_addr); /* Validate memory location choices. */ if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1)) - error("Destination address inappropriately aligned"); + error("Destination physical address inappropriately aligned"); + if (virt_addr & (MIN_KERNEL_ALIGN - 1)) + error("Destination virtual address inappropriately aligned"); #ifdef CONFIG_X86_64 if (heap > 0x3fffffffffffUL) error("Destination address too large"); @@ -382,19 +396,16 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, #endif #ifndef CONFIG_RELOCATABLE if ((unsigned long)output != LOAD_PHYSICAL_ADDR) - error("Wrong destination address"); + error("Destination address does not match LOAD_PHYSICAL_ADDR"); + if ((unsigned long)output != virt_addr) + error("Destination virtual address changed when not relocatable"); #endif debug_putstr("\nDecompressing Linux... "); __decompress(input_data, input_len, NULL, NULL, output, output_len, NULL, error); parse_elf(output); - /* - * 32-bit always performs relocations. 64-bit relocations are only - * needed if kASLR has chosen a different load address. - */ - if (!IS_ENABLED(CONFIG_X86_64) || output != output_orig) - handle_relocations(output, output_len); + handle_relocations(output, output_len, virt_addr); debug_putstr("done.\nBooting the kernel.\n"); return output; } diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h index 09c4ddd02ac6..1c8355eadbd1 100644 --- a/arch/x86/boot/compressed/misc.h +++ b/arch/x86/boot/compressed/misc.h @@ -67,20 +67,22 @@ int cmdline_find_option_bool(const char *option); #if CONFIG_RANDOMIZE_BASE /* kaslr.c */ -unsigned char *choose_random_location(unsigned long input_ptr, - unsigned long input_size, - unsigned long output_ptr, - unsigned long output_size); +void choose_random_location(unsigned long input, + unsigned long input_size, + unsigned long *output, + unsigned long output_size, + unsigned long *virt_addr); /* cpuflags.c */ bool has_cpuflag(int flag); #else -static inline -unsigned char *choose_random_location(unsigned long input_ptr, - unsigned long input_size, - unsigned long output_ptr, - unsigned long output_size) +static inline void choose_random_location(unsigned long input, + unsigned long input_size, + unsigned long *output, + unsigned long output_size, + unsigned long *virt_addr) { - return (unsigned char *)output_ptr; + /* No change from existing output location. */ + *virt_addr = *output; } #endif |