diff options
Diffstat (limited to 'src/fips.c')
| -rw-r--r-- | src/fips.c | 167 |
1 files changed, 96 insertions, 71 deletions
@@ -593,22 +593,20 @@ run_random_selftests (void) # endif #define HMAC_LEN 32 -static const unsigned char __attribute__ ((section (".rodata1"))) -hmac_for_the_implementation[HMAC_LEN]; - /* - * In the ELF file opened as FP, determine the offset of the given - * virtual address ADDR and return it in R_OFFSET1. Determine the - * offset of last loadable section in R_OFFSET2. Rewinds FP to the - * beginning on success. + * In the ELF file opened as FP, fill the ELF header to the pointer + * EHDR_P, determine the offset of last loadable segment in R_OFFSET. + * Also, find the section which contains the hmac value and return it + * in HMAC. Rewinds FP to the beginning on success. */ static gpg_error_t -get_file_offsets (FILE *fp, unsigned long addr, ElfW (Ehdr) *ehdr_p, - unsigned long *r_offset1, unsigned long *r_offset2) +get_file_offset (FILE *fp, ElfW (Ehdr) *ehdr_p, + unsigned long *r_offset, unsigned char hmac[HMAC_LEN]) { ElfW (Phdr) phdr; - uint16_t e_phidx; - long pos = 0; + ElfW (Shdr) shdr; + int i; + unsigned long off_segment = 0; /* Read the ELF header */ if (fseek (fp, 0, SEEK_SET) != 0) @@ -616,12 +614,6 @@ get_file_offsets (FILE *fp, unsigned long addr, ElfW (Ehdr) *ehdr_p, if (fread (ehdr_p, sizeof (*ehdr_p), 1, fp) != 1) return gpg_error_from_syserror (); - /* Fix up the ELF header, clean all section information. */ - ehdr_p->e_shoff = 0; - ehdr_p->e_shentsize = 0; - ehdr_p->e_shnum = 0; - ehdr_p->e_shstrndx = 0; - /* The program header entry size should match the size of the phdr struct */ if (ehdr_p->e_phentsize != sizeof (phdr)) return gpg_error (GPG_ERR_INV_OBJ); @@ -632,11 +624,9 @@ get_file_offsets (FILE *fp, unsigned long addr, ElfW (Ehdr) *ehdr_p, if (fseek (fp, ehdr_p->e_phoff, SEEK_SET) != 0) return gpg_error_from_syserror (); - /* Iterate over the program headers, compare their virtual addresses - with the address we are looking for, and if the program header - matches, calculate the offset of the given ADDR in the file using - the program header's p_offset field. */ - for (e_phidx = 0; e_phidx < ehdr_p->e_phnum; e_phidx++) + /* Iterate over the program headers, determine the last loadable + segment. */ + for (i = 0; i < ehdr_p->e_phnum; i++) { if (fread (&phdr, sizeof (phdr), 1, fp) != 1) return gpg_error_from_syserror (); @@ -647,45 +637,100 @@ get_file_offsets (FILE *fp, unsigned long addr, ElfW (Ehdr) *ehdr_p, if (phdr.p_type != PT_LOAD) break; - pos = phdr.p_offset + phdr.p_filesz; - if (phdr.p_vaddr <= addr && addr < phdr.p_vaddr + phdr.p_memsz) - /* Found segment, compute the offset of ADDR in the file */ - *r_offset1 = phdr.p_offset + (addr - phdr.p_vaddr); + off_segment = phdr.p_offset + phdr.p_filesz; } - if (*r_offset1) + if (!off_segment) + /* The segment not found in the file */ + return gpg_error (GPG_ERR_INV_OBJ); + + /* The section header entry size should match the size of the shdr struct */ + if (ehdr_p->e_shentsize != sizeof (shdr)) + return gpg_error (GPG_ERR_INV_OBJ); + if (ehdr_p->e_shoff == 0) + return gpg_error (GPG_ERR_INV_OBJ); + + /* Jump to the first section header */ + if (fseek (fp, ehdr_p->e_shoff, SEEK_SET) != 0) + return gpg_error_from_syserror (); + + /* Iterate over the section headers, determine the note section, + read the hmac value. */ + for (i = 0; i < ehdr_p->e_shnum; i++) { - if (fseek (fp, 0, SEEK_SET) != 0) + long off; + + if (fread (&shdr, sizeof (shdr), 1, fp) != 1) return gpg_error_from_syserror (); - *r_offset2 = (unsigned long)pos; - return 0; + off = ftell (fp); + if (shdr.sh_type == SHT_NOTE && shdr.sh_flags == 0 && shdr.sh_size == 48) + { + const char header_of_the_note[] = { + 0x04, 0x00, 0x00, 0x00, + 0x20, 0x00, 0x00, 0x00, + 0xca, 0xfe, 0x2a, 0x8e, + 'F', 'D', 'O', 0x00 + }; + unsigned char header[16]; + + /* Jump to the note section. */ + if (fseek (fp, shdr.sh_offset, SEEK_SET) != 0) + return gpg_error_from_syserror (); + + if (fread (header, sizeof (header), 1, fp) != 1) + return gpg_error_from_syserror (); + + if (!memcmp (header, header_of_the_note, 16)) + { + /* Found. Read the hmac value into HMAC. */ + if (fread (hmac, HMAC_LEN, 1, fp) != 1) + return gpg_error_from_syserror (); + break; + } + + /* Back to the next section header. */ + if (fseek (fp, off, SEEK_SET) != 0) + return gpg_error_from_syserror (); + } } - /* Segment not found in the file */ - return gpg_error (GPG_ERR_INV_OBJ); + if (i == ehdr_p->e_shnum) + /* The note section not found. */ + return gpg_error (GPG_ERR_INV_OBJ); + + /* Fix up the ELF header, clean all section information. */ + ehdr_p->e_shoff = 0; + ehdr_p->e_shentsize = 0; + ehdr_p->e_shnum = 0; + ehdr_p->e_shstrndx = 0; + + *r_offset = off_segment; + if (fseek (fp, 0, SEEK_SET) != 0) + return gpg_error_from_syserror (); + + return 0; } static gpg_error_t -hmac256_check (const char *filename, const char *key, struct link_map *lm) +hmac256_check (const char *filename, const char *key) { gpg_error_t err; FILE *fp; gcry_md_hd_t hd; - size_t buffer_size, nread; + const size_t buffer_size = 32768; + size_t nread; char *buffer; - unsigned long addr; - unsigned long offset1 = 0; - unsigned long offset2 = 0; + unsigned long offset = 0; unsigned long pos = 0; ElfW (Ehdr) ehdr; + unsigned char hmac[HMAC_LEN]; - addr = (unsigned long)hmac_for_the_implementation - lm->l_addr; fp = fopen (filename, "rb"); if (!fp) return gpg_error (GPG_ERR_INV_OBJ); - err = get_file_offsets (fp, addr, &ehdr, &offset1, &offset2); + err = get_file_offset (fp, &ehdr, &offset, hmac); if (err) { fclose (fp); @@ -707,8 +752,7 @@ hmac256_check (const char *filename, const char *key, struct link_map *lm) return err; } - buffer_size = 32768; - buffer = xtrymalloc (buffer_size + HMAC_LEN); + buffer = xtrymalloc (buffer_size); if (!buffer) { err = gpg_error_from_syserror (); @@ -717,38 +761,21 @@ hmac256_check (const char *filename, const char *key, struct link_map *lm) return err; } - nread = fread (buffer, 1, HMAC_LEN, fp); - pos += nread; - if (nread < HMAC_LEN) - { - xfree (buffer); - fclose (fp); - _gcry_md_close (hd); - return gpg_error (GPG_ERR_TOO_SHORT); - } - while (1) { - nread = fread (buffer+HMAC_LEN, 1, buffer_size, fp); - if (pos + nread >= offset2) - nread = offset2 - pos; + nread = fread (buffer, 1, buffer_size, fp); + if (pos + nread >= offset) + nread = offset - pos; - /* Copy, fixed ELF header at the beginning. */ - if (pos - HMAC_LEN == 0) + /* Copy the fixed ELF header at the beginning. */ + if (pos == 0) memcpy (buffer, &ehdr, sizeof (ehdr)); + _gcry_md_write (hd, buffer, nread); + if (nread < buffer_size) - { - if (pos - HMAC_LEN <= offset1 && offset1 <= pos + nread) - memset (buffer + HMAC_LEN + offset1 - pos, 0, HMAC_LEN); - _gcry_md_write (hd, buffer, nread+HMAC_LEN); - break; - } + break; - if (pos - HMAC_LEN <= offset1 && offset1 <= pos + nread) - memset (buffer + HMAC_LEN + offset1 - pos, 0, HMAC_LEN); - _gcry_md_write (hd, buffer, nread); - memcpy (buffer, buffer+buffer_size, HMAC_LEN); pos += nread; } @@ -759,7 +786,7 @@ hmac256_check (const char *filename, const char *key, struct link_map *lm) unsigned char *digest; digest = _gcry_md_read (hd, 0); - if (!memcmp (digest, hmac_for_the_implementation, HMAC_LEN)) + if (!memcmp (digest, hmac, HMAC_LEN)) /* Success. */ err = 0; else @@ -780,13 +807,11 @@ check_binary_integrity (void) gpg_error_t err; Dl_info info; const char *key = KEY_FOR_BINARY_CHECK; - void *extra_info; - if (!dladdr1 (hmac_for_the_implementation, &info, &extra_info, - RTLD_DL_LINKMAP)) + if (!dladdr (hmac256_check, &info)) err = gpg_error_from_syserror (); else - err = hmac256_check (info.dli_fname, key, extra_info); + err = hmac256_check (info.dli_fname, key); reporter ("binary", 0, NULL, err? gpg_strerror (err):NULL); #ifdef HAVE_SYSLOG |