diff options
| -rw-r--r-- | certs/Kconfig | 16 | ||||
| -rw-r--r-- | certs/system_certificates.S | 12 | ||||
| -rw-r--r-- | scripts/.gitignore | 1 | ||||
| -rw-r--r-- | scripts/Makefile | 1 | ||||
| -rw-r--r-- | scripts/insert-sys-cert.c | 410 |
5 files changed, 440 insertions, 0 deletions
diff --git a/certs/Kconfig b/certs/Kconfig index b030b9c7ed34..f0f8a4433685 100644 --- a/certs/Kconfig +++ b/certs/Kconfig @@ -39,4 +39,20 @@ config SYSTEM_TRUSTED_KEYS form of DER-encoded *.x509 files in the top-level build directory, those are no longer used. You will need to set this option instead. +config SYSTEM_EXTRA_CERTIFICATE + bool "Reserve area for inserting a certificate without recompiling" + depends on SYSTEM_TRUSTED_KEYRING + help + If set, space for an extra certificate will be reserved in the kernel + image. This allows introducing a trusted certificate to the default + system keyring without recompiling the kernel. + +config SYSTEM_EXTRA_CERTIFICATE_SIZE + int "Number of bytes to reserve for the extra certificate" + depends on SYSTEM_EXTRA_CERTIFICATE + default 4096 + help + This is the number of bytes reserved in the kernel image for a + certificate to be inserted. + endmenu diff --git a/certs/system_certificates.S b/certs/system_certificates.S index 9216e8c81764..f82e1b22eac4 100644 --- a/certs/system_certificates.S +++ b/certs/system_certificates.S @@ -13,6 +13,18 @@ __cert_list_start: .incbin "certs/x509_certificate_list" __cert_list_end: +#ifdef CONFIG_SYSTEM_EXTRA_CERTIFICATE + .globl VMLINUX_SYMBOL(system_extra_cert) + .size system_extra_cert, CONFIG_SYSTEM_EXTRA_CERTIFICATE_SIZE +VMLINUX_SYMBOL(system_extra_cert): + .fill CONFIG_SYSTEM_EXTRA_CERTIFICATE_SIZE, 1, 0 + + .globl VMLINUX_SYMBOL(system_extra_cert_used) +VMLINUX_SYMBOL(system_extra_cert_used): + .int 0 + +#endif /* CONFIG_SYSTEM_EXTRA_CERTIFICATE */ + .align 8 .globl VMLINUX_SYMBOL(system_certificate_list_size) VMLINUX_SYMBOL(system_certificate_list_size): diff --git a/scripts/.gitignore b/scripts/.gitignore index 1f78169d4254..e063daa3ec4a 100644 --- a/scripts/.gitignore +++ b/scripts/.gitignore @@ -13,3 +13,4 @@ sortextable asn1_compiler extract-cert sign-file +insert-sys-cert diff --git a/scripts/Makefile b/scripts/Makefile index fd0d53d4a234..822ab4a6a4aa 100644 --- a/scripts/Makefile +++ b/scripts/Makefile @@ -19,6 +19,7 @@ hostprogs-$(CONFIG_BUILDTIME_EXTABLE_SORT) += sortextable hostprogs-$(CONFIG_ASN1) += asn1_compiler hostprogs-$(CONFIG_MODULE_SIG) += sign-file hostprogs-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += extract-cert +hostprogs-$(CONFIG_SYSTEM_EXTRA_CERTIFICATE) += insert-sys-cert HOSTCFLAGS_sortextable.o = -I$(srctree)/tools/include HOSTCFLAGS_asn1_compiler.o = -I$(srctree)/include diff --git a/scripts/insert-sys-cert.c b/scripts/insert-sys-cert.c new file mode 100644 index 000000000000..8902836c2342 --- /dev/null +++ b/scripts/insert-sys-cert.c @@ -0,0 +1,410 @@ +/* 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); +} |