/* Write the contents of the <certfile> into kernel symbol system_extra_cert * * Copyright (C) IBM Corporation, 2015 * * Author: Mehmet Kayaalp <mkayaalp@linux.vnet.ibm.com> * * This software may be used and distributed according to the terms * of the GNU General Public License, incorporated herein by reference. * * Usage: insert-sys-cert [-s <System.map> -b <vmlinux> -c <certfile> */ #define _GNU_SOURCE#include <stdio.h>#include <ctype.h>#include <string.h>#include <limits.h>#include <stdbool.h>#include <errno.h>#include <stdlib.h>#include <stdarg.h>#include <sys/types.h>#include <sys/stat.h>#include <sys/mman.h>#include <fcntl.h>#include <unistd.h>#include <elf.h> #define CERT_SYM  "system_extra_cert"#define USED_SYM  "system_extra_cert_used"#define LSIZE_SYM "system_certificate_list_size" #define info(format, args...) fprintf(stderr, "INFO:    " format, ## args)#define warn(format, args...) fprintf(stdout, "WARNING: " format, ## args)#define  err(format, args...) fprintf(stderr, "ERROR:   " format, ## args) #if UINTPTR_MAX == 0xffffffff#define CURRENT_ELFCLASS ELFCLASS32#define Elf_Ehdr	Elf32_Ehdr#define Elf_Shdr	Elf32_Shdr#define Elf_Sym		Elf32_Sym#else#define CURRENT_ELFCLASS ELFCLASS64#define Elf_Ehdr	Elf64_Ehdr#define Elf_Shdr	Elf64_Shdr#define Elf_Sym		Elf64_Sym#endif static unsigned char endianness(void){	uint16_t two_byte = 0x00FF;	uint8_t low_address = *((uint8_t *)&two_byte); 	if (low_address == 0)		return ELFDATA2MSB;	else		return ELFDATA2LSB;} struct sym {	char *name;	unsigned long address;	unsigned long offset;	void *content;	int size;}; static unsigned long get_offset_from_address(Elf_Ehdr *hdr, unsigned long addr){	Elf_Shdr *x;	unsigned int i, num_sections; 	x = (void *)hdr + hdr->e_shoff;	if (hdr->e_shnum == SHN_UNDEF)		num_sections = x[0].sh_size;	else		num_sections = hdr->e_shnum; 	for (i = 1; i < num_sections; i++) {		unsigned long start = x[i].sh_addr;		unsigned long end = start + x[i].sh_size;		unsigned long offset = x[i].sh_offset; 		if (addr >= start && addr <= end)			return addr - start + offset;	}	return 0;}  #define LINE_SIZE 100 static void get_symbol_from_map(Elf_Ehdr *hdr, FILE *f, char *name,				struct sym *s){	char l[LINE_SIZE];	char *w, *p, *n; 	s->size = 0;	s->address = 0;	s->offset = 0;	if (fseek(f, 0, SEEK_SET) != 0) {		perror("File seek failed");		exit(EXIT_FAILURE);	}	while (fgets(l, LINE_SIZE, f)) {		p = strchr(l, '\n');		if (!p) {			err("Missing line ending.\n");			return;		}		n = strstr(l, name);		if (n)			break;	}	if (!n) {		err("Unable to find symbol: %s\n", name);		return;	}	w = strchr(l, ' ');	if (!w)		return; 	*w = '\0';	s->address = strtoul(l, NULL, 16);	if (s->address == 0)		return;	s->offset = get_offset_from_address(hdr, s->address);	s->name = name;	s->content = (void *)hdr + s->offset;} static Elf_Sym *find_elf_symbol(Elf_Ehdr *hdr, Elf_Shdr *symtab, char *name){	Elf_Sym *sym, *symtab_start;	char *strtab, *symname;	unsigned int link;	Elf_Shdr *x;	int i, n; 	x = (void *)hdr + hdr->e_shoff;	link = symtab->sh_link;	symtab_start = (void *)hdr + symtab->sh_offset;	n = symtab->sh_size / symtab->sh_entsize;	strtab = (void *)hdr + x[link].sh_offset; 	for (i = 0; i < n; i++) {		sym = &symtab_start[i];		symname = strtab + sym->st_name;		if (strcmp(symname, name) == 0)			return sym;	}	err("Unable to find symbol: %s\n", name);	return NULL;} static void get_symbol_from_table(Elf_Ehdr *hdr, Elf_Shdr *symtab,				  char *name, struct sym *s){	Elf_Shdr *sec;	int secndx;	Elf_Sym *elf_sym;	Elf_Shdr *x; 	x = (void *)hdr + hdr->e_shoff;	s->size = 0;	s->address = 0;	s->offset = 0;	elf_sym = find_elf_symbol(hdr, symtab, name);	if (!elf_sym)		return;	secndx = elf_sym->st_shndx;	if (!secndx)		return;	sec = &x[secndx];	s->size = elf_sym->st_size;	s->address = elf_sym->st_value;	s->offset = s->address - sec->sh_addr			       + sec->sh_offset;	s->name = name;	s->content = (void *)hdr + s->offset;} static Elf_Shdr *get_symbol_table(Elf_Ehdr *hdr){	Elf_Shdr *x;	unsigned int i, num_sections; 	x = (void *)hdr + hdr->e_shoff;	if (hdr->e_shnum == SHN_UNDEF)		num_sections = x[0].sh_size;	else		num_sections = hdr->e_shnum; 	for (i = 1; i < num_sections; i++)		if (x[i].sh_type == SHT_SYMTAB)			return &x[i];	return NULL;} static void *map_file(char *file_name, int *size){	struct stat st;	void *map;	int fd; 	fd = open(file_name, O_RDWR);	if (fd < 0) {		perror(file_name);		return NULL;	}	if (fstat(fd, &st)) {		perror("Could not determine file size");		close(fd);		return NULL;	}	*size = st.st_size;	map = mmap(NULL, *size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);	if (map == MAP_FAILED) {		perror("Mapping to memory failed");		close(fd);		return NULL;	}	close(fd);	return map;} static char *read_file(char *file_name, int *size){	struct stat st;	char *buf;	int fd; 	fd = open(file_name, O_RDONLY);	if (fd < 0) {		perror(file_name);		return NULL;	}	if (fstat(fd, &st)) {		perror("Could not determine file size");		close(fd);		return NULL;	}	*size = st.st_size;	buf = malloc(*size);	if (!buf) {		perror("Allocating memory failed");		close(fd);		return NULL;	}	if (read(fd, buf, *size) != *size) {		perror("File read failed");		close(fd);		return NULL;	}	close(fd);	return buf;} static void print_sym(Elf_Ehdr *hdr, struct sym *s){	info("sym:    %s\n", s->name);	info("addr:   0x%lx\n", s->address);	info("size:   %d\n", s->size);	info("offset: 0x%lx\n", (unsigned long)s->offset);} static void print_usage(char *e){	printf("Usage %s [-s <System.map>] -b <vmlinux> -c <certfile>\n", e);} int main(int argc, char **argv){	char *system_map_file = NULL;	char *vmlinux_file = NULL;	char *cert_file = NULL;	int vmlinux_size;	int cert_size;	Elf_Ehdr *hdr;	char *cert;	FILE *system_map;	unsigned long *lsize;	int *used;	int opt;	Elf_Shdr *symtab = NULL;	struct sym cert_sym, lsize_sym, used_sym; 	while ((opt = getopt(argc, argv, "b:c:s:")) != -1) {		switch (opt) {		case 's':			system_map_file = optarg;			break;		case 'b':			vmlinux_file = optarg;			break;		case 'c':			cert_file = optarg;			break;		default:			break;		}	} 	if (!vmlinux_file || !cert_file) {		print_usage(argv[0]);		exit(EXIT_FAILURE);	} 	cert = read_file(cert_file, &cert_size);	if (!cert)		exit(EXIT_FAILURE); 	hdr = map_file(vmlinux_file, &vmlinux_size);	if (!hdr)		exit(EXIT_FAILURE); 	if (vmlinux_size < sizeof(*hdr)) {		err("Invalid ELF file.\n");		exit(EXIT_FAILURE);	} 	if ((hdr->e_ident[EI_MAG0] != ELFMAG0) ||	    (hdr->e_ident[EI_MAG1] != ELFMAG1) ||	    (hdr->e_ident[EI_MAG2] != ELFMAG2) ||	    (hdr->e_ident[EI_MAG3] != ELFMAG3)) {		err("Invalid ELF magic.\n");		exit(EXIT_FAILURE);	} 	if (hdr->e_ident[EI_CLASS] != CURRENT_ELFCLASS) {		err("ELF class mismatch.\n");		exit(EXIT_FAILURE);	} 	if (hdr->e_ident[EI_DATA] != endianness()) {		err("ELF endian mismatch.\n");		exit(EXIT_FAILURE);	} 	if (hdr->e_shoff > vmlinux_size) {		err("Could not find section header.\n");		exit(EXIT_FAILURE);	} 	symtab = get_symbol_table(hdr);	if (!symtab) {		warn("Could not find the symbol table.\n");		if (!system_map_file) {			err("Please provide a System.map file.\n");			print_usage(argv[0]);			exit(EXIT_FAILURE);		} 		system_map = fopen(system_map_file, "r");		if (!system_map) {			perror(system_map_file);			exit(EXIT_FAILURE);		}		get_symbol_from_map(hdr, system_map, CERT_SYM, &cert_sym);		get_symbol_from_map(hdr, system_map, USED_SYM, &used_sym);		get_symbol_from_map(hdr, system_map, LSIZE_SYM, &lsize_sym);		cert_sym.size = used_sym.address - cert_sym.address;	} else {		info("Symbol table found.\n");		if (system_map_file)			warn("System.map is ignored.\n");		get_symbol_from_table(hdr, symtab, CERT_SYM, &cert_sym);		get_symbol_from_table(hdr, symtab, USED_SYM, &used_sym);		get_symbol_from_table(hdr, symtab, LSIZE_SYM, &lsize_sym);	} 	if (!cert_sym.offset || !lsize_sym.offset || !used_sym.offset)		exit(EXIT_FAILURE); 	print_sym(hdr, &cert_sym);	print_sym(hdr, &used_sym);	print_sym(hdr, &lsize_sym); 	lsize = (unsigned long *)lsize_sym.content;	used = (int *)used_sym.content; 	if (cert_sym.size < cert_size) {		err("Certificate is larger than the reserved area!\n");		exit(EXIT_FAILURE);	} 	/* If the existing cert is the same, don't overwrite */	if (cert_size == *used &&	    strncmp(cert_sym.content, cert, cert_size) == 0) {		warn("Certificate was already inserted.\n");		exit(EXIT_SUCCESS);	} 	if (*used > 0)		warn("Replacing previously inserted certificate.\n"); 	memcpy(cert_sym.content, cert, cert_size);	if (cert_size < cert_sym.size)		memset(cert_sym.content + cert_size,			0, cert_sym.size - cert_size); 	*lsize = *lsize + cert_size - *used;	*used = cert_size;	info("Inserted the contents of %s into %lx.\n", cert_file,						cert_sym.address);	info("Used %d bytes out of %d bytes reserved.\n", *used,						 cert_sym.size);	exit(EXIT_SUCCESS);}