// SPDX-License-Identifier: GPL-2.0 /* * misc.c * * This is a collection of several routines used to extract the kernel * which includes KASLR relocation, decompression, ELF parsing, and * relocation processing. Additionally included are the screen and serial * output functions and related debugging support functions. * * malloc by Hannu Savolainen 1993 and Matthias Urlichs 1994 * puts by Nick Holloway 1993, better puts by Martin Mares 1995 * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996 */ #include "misc.h" #include "error.h" #include "pgtable.h" #include "../string.h" #include "../voffset.h" #include <asm/bootparam_utils.h> /* * WARNING!! * This code is compiled with -fPIC and it is relocated dynamically at * run time, but no relocation processing is performed. This means that * it is not safe to place pointers in static structures. */ /* Macros used by the included decompressor code below. */ #define STATIC static /* Define an externally visible malloc()/free(). */ #define MALLOC_VISIBLE #include <linux/decompress/mm.h> /* * Provide definitions of memzero and memmove as some of the decompressors will * try to define their own functions if these are not defined as macros. */ #define memzero(s, n) memset((s), 0, (n)) #ifndef memmove #define memmove memmove /* Functions used by the included decompressor code below. */ void *memmove(void *dest, const void *src, size_t n); #endif /* * This is set up by the setup-routine at boot-time */ struct boot_params *boot_params; struct port_io_ops pio_ops; memptr free_mem_ptr; memptr free_mem_end_ptr; static char *vidmem; static int vidport; /* These might be accessed before .bss is cleared, so use .data instead. */ static int lines __section(".data"); static int cols __section(".data"); #ifdef CONFIG_KERNEL_GZIP #include "../../../../lib/decompress_inflate.c" #endif #ifdef CONFIG_KERNEL_BZIP2 #include "../../../../lib/decompress_bunzip2.c" #endif #ifdef CONFIG_KERNEL_LZMA #include "../../../../lib/decompress_unlzma.c" #endif #ifdef CONFIG_KERNEL_XZ #include "../../../../lib/decompress_unxz.c" #endif #ifdef CONFIG_KERNEL_LZO #include "../../../../lib/decompress_unlzo.c" #endif #ifdef CONFIG_KERNEL_LZ4 #include "../../../../lib/decompress_unlz4.c" #endif #ifdef CONFIG_KERNEL_ZSTD #include "../../../../lib/decompress_unzstd.c" #endif /* * NOTE: When adding a new decompressor, please update the analysis in * ../header.S. */ static void scroll(void) { int i; memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2); for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2) vidmem[i] = ' '; } #define XMTRDY 0x20 #define TXR 0 /* Transmit register (WRITE) */ #define LSR 5 /* Line Status */ static void serial_putchar(int ch) { unsigned timeout = 0xffff; while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout) cpu_relax(); outb(ch, early_serial_base + TXR); } void __putstr(const char *s) { int x, y, pos; char c; if (early_serial_base) { const char *str = s; while (*str) { if (*str == '\n') serial_putchar('\r'); serial_putchar(*str++); } } if (lines == 0 || cols == 0) return; x = boot_params->screen_info.orig_x; y = boot_params->screen_info.orig_y; while ((c = *s++) != '\0') { if (c == '\n') { x = 0; if (++y >= lines) { scroll(); y--; } } else { vidmem[(x + cols * y) * 2] = c; if (++x >= cols) { x = 0; if (++y >= lines) { scroll(); y--; } } } } boot_params->screen_info.orig_x = x; boot_params->screen_info.orig_y = y; pos = (x + cols * y) * 2; /* Update cursor position */ outb(14, vidport); outb(0xff & (pos >> 9), vidport+1); outb(15, vidport); outb(0xff & (pos >> 1), vidport+1); } void __puthex(unsigned long value) { char alpha[2] = "0"; int bits; for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) { unsigned long digit = (value >> bits) & 0xf; if (digit < 0xA) alpha[0] = '0' + digit; else alpha[0] = 'a' + (digit - 0xA); __putstr(alpha); } } #ifdef CONFIG_X86_NEED_RELOCS static void handle_relocations(void *output, unsigned long output_len, unsigned long virt_addr) { int *reloc; unsigned long delta, map, ptr; unsigned long min_addr = (unsigned long)output; unsigned long max_addr = min_addr + (VO___bss_start - VO__text); /* * Calculate the delta between where vmlinux was linked to load * and where it was actually loaded. */ delta = min_addr - LOAD_PHYSICAL_ADDR; /* * The kernel contains a table of relocation addresses. Those * addresses have the final load address of the kernel in virtual * memory. We are currently working in the self map. So we need to * create an adjustment for kernel memory addresses to the self map. * This will involve subtracting out the base address of the kernel. */ 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 * address of the location which needs to be updated stored as a * 32-bit value which is sign extended to 64 bits. * * Format is: * * kernel bits... * 0 - zero terminator for 64 bit relocations * 64 bit relocation repeated * 0 - zero terminator for inverse 32 bit relocations * 32 bit inverse relocation repeated * 0 - zero terminator for 32 bit relocations * 32 bit relocation repeated * * So we work backwards from the end of the decompressed image. */ for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) { long extended = *reloc; extended += map; ptr = (unsigned long)extended; if (ptr < min_addr || ptr > max_addr) error("32-bit relocation outside of kernel!\n"); *(uint32_t *)ptr += delta; } #ifdef CONFIG_X86_64 while (*--reloc) { long extended = *reloc; extended += map; ptr = (unsigned long)extended; if (ptr < min_addr || ptr > max_addr) error("inverse 32-bit relocation outside of kernel!\n"); *(int32_t *)ptr -= delta; } for (reloc--; *reloc; reloc--) { long extended = *reloc; extended += map; ptr = (unsigned long)extended; if (ptr < min_addr || ptr > max_addr) error("64-bit relocation outside of kernel!\n"); *(uint64_t *)ptr += delta; } #endif } #else static inline void handle_relocations(void *output, unsigned long output_len, unsigned long virt_addr) { } #endif static void parse_elf(void *output) { #ifdef CONFIG_X86_64 Elf64_Ehdr ehdr; Elf64_Phdr *phdrs, *phdr; #else Elf32_Ehdr ehdr; Elf32_Phdr *phdrs, *phdr; #endif void *dest; int i; memcpy(&ehdr, output, sizeof(ehdr)); if (ehdr.e_ident[EI_MAG0] != ELFMAG0 || ehdr.e_ident[EI_MAG1] != ELFMAG1 || ehdr.e_ident[EI_MAG2] != ELFMAG2 || ehdr.e_ident[EI_MAG3] != ELFMAG3) { error("Kernel is not a valid ELF file"); return; } debug_putstr("Parsing ELF... "); phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum); if (!phdrs) error("Failed to allocate space for phdrs"); memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum); for (i = 0; i < ehdr.e_phnum; i++) { phdr = &phdrs[i]; switch (phdr->p_type) { case PT_LOAD: #ifdef CONFIG_X86_64 if ((phdr->p_align % 0x200000) != 0) error("Alignment of LOAD segment isn't multiple of 2MB"); #endif #ifdef CONFIG_RELOCATABLE dest = output; dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR); #else dest = (void *)(phdr->p_paddr); #endif memmove(dest, output + phdr->p_offset, phdr->p_filesz); break; default: /* Ignore other PT_* */ break; } } free(phdrs); } /* * The compressed kernel image (ZO), has been moved so that its position * is against the end of the buffer used to hold the uncompressed kernel * image (VO) and the execution environment (.bss, .brk), which makes sure * there is room to do the in-place decompression. (See header.S for the * calculations.) * * |-----compressed kernel image------| * V V * 0 extract_offset +INIT_SIZE * |-----------|---------------|-------------------------|--------| * | | | | * VO__text startup_32 of ZO VO__end ZO__end * ^ ^ * |-------uncompressed kernel image---------| * */ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, unsigned char *input_data, unsigned long input_len, unsigned char *output, unsigned long output_len) { const unsigned long kernel_total_size = VO__end - VO__text; unsigned long virt_addr = LOAD_PHYSICAL_ADDR; unsigned long needed_size; /* Retain x86 boot parameters pointer passed from startup_32/64. */ boot_params = rmode; /* Clear flags intended for solely in-kernel use. */ boot_params->hdr.loadflags &= ~KASLR_FLAG; sanitize_boot_params(boot_params); if (boot_params->screen_info.orig_video_mode == 7) { vidmem = (char *) 0xb0000; vidport = 0x3b4; } else { vidmem = (char *) 0xb8000; vidport = 0x3d4; } lines = boot_params->screen_info.orig_video_lines; cols = boot_params->screen_info.orig_video_cols; init_default_io_ops(); /* * Detect TDX guest environment. * * It has to be done before console_init() in order to use * paravirtualized port I/O operations if needed. */ early_tdx_detect(); console_init(); /* * Save RSDP address for later use. Have this after console_init() * so that early debugging output from the RSDP parsing code can be * collected. */ boot_params->acpi_rsdp_addr = get_rsdp_addr(); debug_putstr("early console in extract_kernel\n"); free_mem_ptr = heap; /* Heap */ free_mem_end_ptr = heap + BOOT_HEAP_SIZE; /* * The memory hole needed for the kernel is the larger of either * the entire decompressed kernel plus relocation table, or the * entire decompressed kernel plus .bss and .brk sections. * * On X86_64, the memory is mapped with PMD pages. Round the * size up so that the full extent of PMD pages mapped is * included in the check against the valid memory table * entries. This ensures the full mapped area is usable RAM * and doesn't include any reserved areas. */ needed_size = max(output_len, kernel_total_size); #ifdef CONFIG_X86_64 needed_size = ALIGN(needed_size, MIN_KERNEL_ALIGN); #endif /* Report initial kernel position details. */ debug_putaddr(input_data); debug_putaddr(input_len); debug_putaddr(output); debug_putaddr(output_len); debug_putaddr(kernel_total_size); debug_putaddr(needed_size); #ifdef CONFIG_X86_64 /* Report address of 32-bit trampoline */ debug_putaddr(trampoline_32bit); #endif choose_random_location((unsigned long)input_data, input_len, (unsigned long *)&output, needed_size, &virt_addr); /* Validate memory location choices. */ if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1)) 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"); if (virt_addr + max(output_len, kernel_total_size) > KERNEL_IMAGE_SIZE) error("Destination virtual address is beyond the kernel mapping area"); #else if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff)) error("Destination address too large"); #endif #ifndef CONFIG_RELOCATABLE if (virt_addr != LOAD_PHYSICAL_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); handle_relocations(output, output_len, virt_addr); debug_putstr("done.\nBooting the kernel.\n"); /* Disable exception handling before booting the kernel */ cleanup_exception_handling(); return output; } void fortify_panic(const char *name) { error("detected buffer overflow"); }