Verify modules on build-time rather than failing in runtime.
This commit is contained in:
Vladimir Serbinenko
parent
5919626c90
commit
a7cf8b1e23
7 changed files with 468 additions and 3 deletions
315
util/grub-module-verifierXX.c
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315
util/grub-module-verifierXX.c
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#include <string.h>
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#include <grub/elf.h>
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#include <grub/module_verifier.h>
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#include <grub/util/misc.h>
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#if defined(MODULEVERIFIER_ELF32)
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# define SUFFIX(x) x ## 32
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# define ELFCLASSXX ELFCLASS32
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# define Elf_Ehdr Elf32_Ehdr
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# define Elf_Phdr Elf32_Phdr
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# define Elf_Nhdr Elf32_Nhdr
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# define Elf_Addr Elf32_Addr
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# define Elf_Sym Elf32_Sym
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# define Elf_Off Elf32_Off
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# define Elf_Shdr Elf32_Shdr
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# define Elf_Rela Elf32_Rela
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# define Elf_Rel Elf32_Rel
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# define Elf_Word Elf32_Word
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# define Elf_Half Elf32_Half
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# define Elf_Section Elf32_Section
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# define ELF_R_SYM(val) ELF32_R_SYM(val)
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# define ELF_R_TYPE(val) ELF32_R_TYPE(val)
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# define ELF_ST_TYPE(val) ELF32_ST_TYPE(val)
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#elif defined(MODULEVERIFIER_ELF64)
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# define SUFFIX(x) x ## 64
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# define ELFCLASSXX ELFCLASS64
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# define Elf_Ehdr Elf64_Ehdr
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# define Elf_Phdr Elf64_Phdr
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# define Elf_Nhdr Elf64_Nhdr
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# define Elf_Addr Elf64_Addr
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# define Elf_Sym Elf64_Sym
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# define Elf_Off Elf64_Off
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# define Elf_Shdr Elf64_Shdr
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# define Elf_Rela Elf64_Rela
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# define Elf_Rel Elf64_Rel
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# define Elf_Word Elf64_Word
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# define Elf_Half Elf64_Half
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# define Elf_Section Elf64_Section
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# define ELF_R_SYM(val) ELF64_R_SYM(val)
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# define ELF_R_TYPE(val) ELF64_R_TYPE(val)
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# define ELF_ST_TYPE(val) ELF64_ST_TYPE(val)
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#else
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#error "I'm confused"
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#endif
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#define grub_target_to_host32(x) (grub_target_to_host32_real (arch, (x)))
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#define grub_host_to_target32(x) (grub_host_to_target32_real (arch, (x)))
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#define grub_target_to_host64(x) (grub_target_to_host64_real (arch, (x)))
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#define grub_host_to_target64(x) (grub_host_to_target64_real (arch, (x)))
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#define grub_host_to_target_addr(x) (grub_host_to_target_addr_real (arch, (x)))
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#define grub_target_to_host16(x) (grub_target_to_host16_real (arch, (x)))
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#define grub_host_to_target16(x) (grub_host_to_target16_real (arch, (x)))
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#define grub_target_to_host(val) grub_target_to_host_real(arch, (val))
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static inline grub_uint32_t
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grub_target_to_host32_real (const struct grub_module_verifier_arch *arch,
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grub_uint32_t in)
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{
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if (arch->bigendian)
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return grub_be_to_cpu32 (in);
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else
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return grub_le_to_cpu32 (in);
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}
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static inline grub_uint64_t
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grub_target_to_host64_real (const struct grub_module_verifier_arch *arch,
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grub_uint64_t in)
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{
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if (arch->bigendian)
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return grub_be_to_cpu64 (in);
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else
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return grub_le_to_cpu64 (in);
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}
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static inline grub_uint64_t
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grub_host_to_target64_real (const struct grub_module_verifier_arch *arch,
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grub_uint64_t in)
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{
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if (arch->bigendian)
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return grub_cpu_to_be64 (in);
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else
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return grub_cpu_to_le64 (in);
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}
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static inline grub_uint32_t
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grub_host_to_target32_real (const struct grub_module_verifier_arch *arch,
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grub_uint32_t in)
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{
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if (arch->bigendian)
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return grub_cpu_to_be32 (in);
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else
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return grub_cpu_to_le32 (in);
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}
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static inline grub_uint16_t
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grub_target_to_host16_real (const struct grub_module_verifier_arch *arch,
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grub_uint16_t in)
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{
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if (arch->bigendian)
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return grub_be_to_cpu16 (in);
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else
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return grub_le_to_cpu16 (in);
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}
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static inline grub_uint16_t
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grub_host_to_target16_real (const struct grub_module_verifier_arch *arch,
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grub_uint16_t in)
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{
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if (arch->bigendian)
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return grub_cpu_to_be16 (in);
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else
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return grub_cpu_to_le16 (in);
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}
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static inline grub_uint64_t
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grub_host_to_target_addr_real (const struct grub_module_verifier_arch *arch, grub_uint64_t in)
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{
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if (arch->voidp_sizeof == 8)
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return grub_host_to_target64_real (arch, in);
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else
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return grub_host_to_target32_real (arch, in);
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}
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static inline grub_uint64_t
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grub_target_to_host_real (const struct grub_module_verifier_arch *arch, grub_uint64_t in)
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{
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if (arch->voidp_sizeof == 8)
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return grub_target_to_host64_real (arch, in);
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else
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return grub_target_to_host32_real (arch, in);
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}
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static Elf_Shdr *
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find_section (const struct grub_module_verifier_arch *arch, Elf_Ehdr *e, const char *name)
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{
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Elf_Shdr *s;
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const char *str;
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unsigned i;
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s = (Elf_Shdr *) ((char *) e + grub_target_to_host (e->e_shoff) + grub_target_to_host16 (e->e_shstrndx) * grub_target_to_host16 (e->e_shentsize));
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str = (char *) e + grub_target_to_host (s->sh_offset);
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for (i = 0, s = (Elf_Shdr *) ((char *) e + grub_target_to_host (e->e_shoff));
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i < grub_target_to_host16 (e->e_shnum);
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i++, s = (Elf_Shdr *) ((char *) s + grub_target_to_host16 (e->e_shentsize)))
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if (strcmp (str + grub_target_to_host32 (s->sh_name), name) == 0)
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return s;
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return NULL;
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}
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static void
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check_license (const struct grub_module_verifier_arch *arch, Elf_Ehdr *e)
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{
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Elf_Shdr *s = find_section (arch, e, ".module_license");
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if (s && (strcmp ((char *) e + grub_target_to_host(s->sh_offset), "LICENSE=GPLv3") == 0
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|| strcmp ((char *) e + grub_target_to_host(s->sh_offset), "LICENSE=GPLv3+") == 0
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|| strcmp ((char *) e + grub_target_to_host(s->sh_offset), "LICENSE=GPLv2+") == 0))
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return;
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grub_util_error ("incompatible license");
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}
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static void
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check_symbols (const struct grub_module_verifier_arch *arch, Elf_Ehdr *e)
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{
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unsigned i;
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Elf_Shdr *s, *sections;
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Elf_Sym *sym;
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const char *str;
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Elf_Word size, entsize;
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sections = (Elf_Shdr *) ((char *) e + grub_target_to_host (e->e_shoff));
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for (i = 0, s = sections;
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i < grub_target_to_host16 (e->e_shnum);
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i++, s = (Elf_Shdr *) ((char *) s + grub_target_to_host16 (e->e_shentsize)))
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if (grub_target_to_host32 (s->sh_type) == SHT_SYMTAB)
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break;
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if (i == grub_target_to_host16 (e->e_shnum))
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grub_util_error ("no symbol table");
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sym = (Elf_Sym *) ((char *) e + grub_target_to_host (s->sh_offset));
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size = grub_target_to_host (s->sh_size);
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entsize = grub_target_to_host (s->sh_entsize);
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s = (Elf_Shdr *) ((char *) sections + grub_target_to_host16 (e->e_shentsize) * grub_target_to_host32 (s->sh_link));
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str = (char *) e + grub_target_to_host (s->sh_offset);
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for (i = 0;
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i < size / entsize;
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i++, sym = (Elf_Sym *) ((char *) sym + entsize))
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{
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unsigned char type = ELF_ST_TYPE (sym->st_info);
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switch (type)
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{
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case STT_NOTYPE:
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case STT_OBJECT:
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case STT_FUNC:
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case STT_SECTION:
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case STT_FILE:
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break;
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default:
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return grub_util_error ("unknown symbol type `%d'", (int) type);
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}
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}
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}
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/* Relocate symbols. */
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static void
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section_check_relocations (const struct grub_module_verifier_arch *arch, void *ehdr,
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Elf_Shdr *s, size_t target_seg_size)
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{
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Elf_Rel *rel, *max;
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for (rel = (Elf_Rel *) ((char *) ehdr + grub_target_to_host (s->sh_offset)),
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max = (Elf_Rel *) ((char *) rel + grub_target_to_host (s->sh_size));
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rel < max;
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rel = (Elf_Rel *) ((char *) rel + grub_target_to_host (s->sh_entsize)))
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{
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Elf_Word *addr;
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Elf_Sym *sym;
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unsigned i;
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if (target_seg_size < grub_target_to_host (rel->r_offset))
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grub_util_error ("reloc offset is out of the segment");
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grub_uint32_t type = ELF_R_TYPE (grub_target_to_host (rel->r_info));
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if (arch->machine == EM_SPARCV9)
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type &= 0xff;
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for (i = 0; arch->supported_relocations[i] != -1; i++)
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if (type == arch->supported_relocations[i])
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break;
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if (arch->supported_relocations[i] == -1)
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grub_util_error ("unsupported relocation 0x%x", type);
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}
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}
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static void
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check_relocations (const struct grub_module_verifier_arch *arch, Elf_Ehdr *e)
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{
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Elf_Shdr *s;
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unsigned i;
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for (i = 0, s = (Elf_Shdr *) ((char *) e + grub_target_to_host (e->e_shoff));
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i < grub_target_to_host16 (e->e_shnum);
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i++, s = (Elf_Shdr *) ((char *) s + grub_target_to_host16 (e->e_shentsize)))
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if (grub_target_to_host32 (s->sh_type) == SHT_REL || grub_target_to_host32 (s->sh_type) == SHT_RELA)
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{
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Elf_Shdr *ts;
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if (grub_target_to_host32 (s->sh_type) == SHT_REL && !(arch->flags & GRUB_MODULE_VERIFY_SUPPORTS_REL))
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grub_util_error ("unsupported SHT_REL");
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if (grub_target_to_host32 (s->sh_type) == SHT_RELA && !(arch->flags & GRUB_MODULE_VERIFY_SUPPORTS_RELA))
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grub_util_error ("unsupported SHT_RELA");
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/* Find the target segment. */
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if (grub_target_to_host32 (s->sh_info) >= grub_target_to_host16 (e->e_shnum))
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grub_util_error ("orphaned reloc section");
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ts = (Elf_Shdr *) ((char *) e + grub_target_to_host (e->e_shoff) + grub_target_to_host32 (s->sh_info) * grub_target_to_host16 (e->e_shentsize));
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section_check_relocations (arch, e, s, grub_target_to_host (ts->sh_size));
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}
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}
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void
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SUFFIX(grub_module_verify) (void *module_img, size_t size, const struct grub_module_verifier_arch *arch)
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{
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Elf_Ehdr *e = module_img;
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/* Check the header size. */
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if (size < sizeof (Elf_Ehdr))
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grub_util_error ("ELF header smaller than expected");
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/* Check the magic numbers. */
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if (e->e_ident[EI_MAG0] != ELFMAG0
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|| e->e_ident[EI_MAG1] != ELFMAG1
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|| e->e_ident[EI_MAG2] != ELFMAG2
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|| e->e_ident[EI_MAG3] != ELFMAG3
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|| e->e_ident[EI_VERSION] != EV_CURRENT
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|| grub_target_to_host32 (e->e_version) != EV_CURRENT)
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grub_util_error ("invalid arch-independent ELF magic");
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if (e->e_ident[EI_CLASS] != ELFCLASSXX
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|| e->e_ident[EI_DATA] != (arch->bigendian ? ELFDATA2MSB : ELFDATA2LSB)
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|| grub_target_to_host16 (e->e_machine) != arch->machine)
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grub_util_error ("invalid arch-dependent ELF magic");
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if (grub_target_to_host16 (e->e_type) != ET_REL)
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{
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grub_util_error ("this ELF file is not of the right type");
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}
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/* Make sure that every section is within the core. */
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if (size < grub_target_to_host (e->e_shoff)
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+ grub_target_to_host16 (e->e_shentsize) * grub_target_to_host16(e->e_shnum))
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{
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grub_util_error ("ELF sections outside core");
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}
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check_license (arch, e);
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Elf_Shdr *s;
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s = find_section (arch, e, ".modname");
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if (!s)
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grub_util_error ("no module name found");
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check_symbols(arch, e);
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check_relocations(arch, e);
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}
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