/*
* verify a module's signature
*/
int module_verify_signature(struct module_verify_data *mvdata)
{
const Elf_Shdr *sechdrs = mvdata->sections;
const char *secstrings = mvdata->secstrings;
const char *sig;
unsigned sig_size;
int i, ret;
for (i = 1; i < mvdata->nsects; i++) {
switch (sechdrs[i].sh_type) {
case SHT_PROGBITS:
if (strcmp(mvdata->secstrings + sechdrs[i].sh_name,
".module_sig") == 0) {
mvdata->sig_index = i;
}
break;
}
}
if (mvdata->sig_index <= 0)
goto no_signature;
sig = mvdata->buffer + sechdrs[mvdata->sig_index].sh_offset;
sig_size = sechdrs[mvdata->sig_index].sh_size;
_debug("sig in section %d (size %d)\n",
mvdata->sig_index, sig_size);
/* produce a canonicalisation map for the sections */
ret = module_verify_canonicalise(mvdata);
if (ret < 0)
return ret;
/* grab an SHA1 transformation context
* - !!! if this tries to load the sha1.ko module, we will deadlock!!!
*/
mvdata->digest = crypto_alloc_tfm2("sha1", 0, 1);
if (!mvdata->digest) {
printk("Couldn't load module - SHA1 transform unavailable\n");
return -EPERM;
}
crypto_digest_init(mvdata->digest);
#ifdef MODSIGN_DEBUG
mvdata->xcsum = 0;
#endif
/* load data from each relevant section into the digest */
for (i = 1; i < mvdata->nsects; i++) {
unsigned long sh_type = sechdrs[i].sh_type;
unsigned long sh_info = sechdrs[i].sh_info;
unsigned long sh_size = sechdrs[i].sh_size;
unsigned long sh_flags = sechdrs[i].sh_flags;
const char *sh_name = secstrings + sechdrs[i].sh_name;
const void *data = mvdata->buffer + sechdrs[i].sh_offset;
if (i == mvdata->sig_index)
continue;
#ifdef MODSIGN_DEBUG
mvdata->csum = 0;
#endif
/* it would be nice to include relocation sections, but the act
* of adding a signature to the module seems changes their
* contents, because the symtab gets changed when sections are
* added or removed */
if (sh_type == SHT_REL || sh_type == SHT_RELA) {
if (mvdata->canonlist[sh_info]) {
uint32_t xsh_info = mvdata->canonmap[sh_info];
crypto_digest_update_data(mvdata, sh_name, strlen(sh_name));
crypto_digest_update_val(mvdata, sechdrs[i].sh_type);
crypto_digest_update_val(mvdata, sechdrs[i].sh_flags);
crypto_digest_update_val(mvdata, sechdrs[i].sh_size);
crypto_digest_update_val(mvdata, sechdrs[i].sh_addralign);
crypto_digest_update_val(mvdata, xsh_info);
if (sh_type == SHT_RELA)
ret = extract_elf_rela(
mvdata, i,
data,
sh_size / sizeof(Elf_Rela),
sh_name);
else
ret = extract_elf_rel(
mvdata, i,
data,
sh_size / sizeof(Elf_Rel),
sh_name);
if (ret < 0)
goto format_error;
}
continue;
}
/* include allocatable loadable sections */
if (sh_type != SHT_NOBITS && sh_flags & SHF_ALLOC)
goto include_section;
continue;
include_section:
crypto_digest_update_data(mvdata, sh_name, strlen(sh_name));
crypto_digest_update_val(mvdata, sechdrs[i].sh_type);
crypto_digest_update_val(mvdata, sechdrs[i].sh_flags);
crypto_digest_update_val(mvdata, sechdrs[i].sh_size);
crypto_digest_update_val(mvdata, sechdrs[i].sh_addralign);
crypto_digest_update_data(mvdata, data, sh_size);
_debug("%08zx %02x digested the %s section, size %ld\n",
mvdata->signed_size, mvdata->csum, sh_name, sh_size);
mvdata->canonlist[i] = 1;
}
_debug("Contributed %zu bytes to the digest (csum 0x%02x)\n",
mvdata->signed_size, mvdata->xcsum);
/* do the actual signature verification */
i = ksign_verify_signature(sig, sig_size, mvdata->digest);
_debug("verify-sig : %d\n", i);
if (i == 0)
i = 1;
return i;
format_error:
crypto_free_tfm(mvdata->digest);
return -ELIBBAD;
/* deal with the case of an unsigned module */
no_signature:
if (!signedonly)
return 0;
printk("An attempt to load unsigned module was rejected\n");
return -EPERM;
} /* end module_verify_signature() */
/*
* verify a module's signature
*/
int module_verify_signature(struct module_verify_data *mvdata,
int *_gpgsig_ok)
{
const struct elf_note *note;
struct crypto_shash *tfm;
const Elf_Shdr *sechdrs = mvdata->sections;
const char *secstrings = mvdata->secstrings;
const char *sig;
unsigned note_size, sig_size, note_namesz;
int loop, ret;
_debug("looking for sig section '%s'\n", modsign_note_section);
for (loop = 1; loop < mvdata->nsects; loop++) {
switch (sechdrs[loop].sh_type) {
case SHT_NOTE:
if (strcmp(mvdata->secstrings + sechdrs[loop].sh_name,
modsign_note_section) == 0)
mvdata->sig_index = loop;
break;
}
}
if (mvdata->sig_index <= 0)
goto no_signature;
note = mvdata->buffer + sechdrs[mvdata->sig_index].sh_offset;
note_size = sechdrs[mvdata->sig_index].sh_size;
/* there should be one note of the appropriate type */
if (note_size < sizeof(*note) + 2 * 4)
goto format_error_no_free;
note_namesz = note->n_namesz;
sig_size = note->n_descsz;
if (note_namesz != sizeof(modsign_note_name))
goto format_error_no_free;
if (note->n_type != MODSIGN_NOTE_TYPE)
goto format_error_no_free;
if (memcmp(note + 1, modsign_note_name, note_namesz) != 0)
goto format_error_no_free;
sig = (void *)(note + 1) + roundup(note_namesz, 4);
_debug("sig in section %d (size %d)\n",
mvdata->sig_index, sig_size);
_debug("%02x%02x%02x%02x%02x%02x%02x%02x\n",
sig[0], sig[1], sig[2], sig[3],
sig[4], sig[5], sig[6], sig[7]);
/* produce a canonicalisation map for the sections */
ret = module_verify_canonicalise(mvdata);
if (ret < 0)
return ret;
/* grab an SHA1 transformation context
* - !!! if this tries to load the sha1.ko module, we will deadlock!!!
*/
tfm = crypto_alloc_shash("sha1", 0, 0);
if (IS_ERR(tfm)) {
printk(KERN_ERR
"Couldn't load module - SHA1 transform unavailable\n");
return -EPERM;
}
mvdata->hash = kmalloc(sizeof(*mvdata->hash) +
crypto_shash_descsize(tfm),
GFP_KERNEL);
if (!mvdata->hash) {
crypto_free_shash(tfm);
return -ENOMEM;
}
mvdata->hash->tfm = tfm;
mvdata->hash->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
ret = crypto_shash_init(mvdata->hash);
if (ret < 0) {
crypto_free_shash(mvdata->hash->tfm);
kfree(mvdata->hash);
return -ENOMEM;
}
#ifdef MODSIGN_DEBUG
mvdata->xcsum = 0;
#endif
/* load data from each relevant section into the digest */
for (loop = 0; loop < mvdata->ncanon; loop++) {
int sect = mvdata->canonlist[loop];
unsigned long sh_type = sechdrs[sect].sh_type;
unsigned long sh_info = sechdrs[sect].sh_info;
unsigned long sh_size = sechdrs[sect].sh_size;
unsigned long sh_flags = sechdrs[sect].sh_flags;
const char *sh_name = secstrings + sechdrs[sect].sh_name;
const void *data = mvdata->buffer + sechdrs[sect].sh_offset;
#ifdef MODSIGN_DEBUG
mvdata->csum = 0;
#endif
/* it would be nice to include relocation sections, but the act
* of adding a signature to the module seems changes their
* contents, because the symtab gets changed when sections are
* added or removed */
if (sh_type == SHT_REL || sh_type == SHT_RELA) {
uint32_t xsh_info = mvdata->canonmap[sh_info];
crypto_digest_update_data(mvdata, sh_name, strlen(sh_name));
crypto_digest_update_val(mvdata, sechdrs[sect].sh_type);
crypto_digest_update_val(mvdata, sechdrs[sect].sh_flags);
crypto_digest_update_val(mvdata, sechdrs[sect].sh_size);
crypto_digest_update_val(mvdata, sechdrs[sect].sh_addralign);
crypto_digest_update_val(mvdata, xsh_info);
if (sh_type == SHT_RELA)
ret = extract_elf_rela(
mvdata, sect,
data,
sh_size / sizeof(Elf_Rela),
sh_name);
else
ret = extract_elf_rel(
mvdata, sect,
data,
sh_size / sizeof(Elf_Rel),
sh_name);
if (ret < 0)
goto format_error;
continue;
}
/* include the headers of BSS sections */
if (sh_type == SHT_NOBITS && sh_flags & SHF_ALLOC) {
crypto_digest_update_data(mvdata, sh_name, strlen(sh_name));
crypto_digest_update_val(mvdata, sechdrs[sect].sh_type);
crypto_digest_update_val(mvdata, sechdrs[sect].sh_flags);
crypto_digest_update_val(mvdata, sechdrs[sect].sh_size);
crypto_digest_update_val(mvdata, sechdrs[sect].sh_addralign);
goto digested;
}
/* include allocatable loadable sections */
if (sh_type != SHT_NOBITS && sh_flags & SHF_ALLOC)
goto include_section;
continue;
include_section:
crypto_digest_update_data(mvdata, sh_name, strlen(sh_name));
crypto_digest_update_val(mvdata, sechdrs[sect].sh_type);
crypto_digest_update_val(mvdata, sechdrs[sect].sh_flags);
crypto_digest_update_val(mvdata, sechdrs[sect].sh_size);
crypto_digest_update_val(mvdata, sechdrs[sect].sh_addralign);
crypto_digest_update_data(mvdata, data, sh_size);
digested:
_debug("%08zx %02x digested the %s section, size %ld\n",
mvdata->signed_size, mvdata->csum, sh_name, sh_size);
}
_debug("Contributed %zu bytes to the digest (csum 0x%02x)\n",
mvdata->signed_size, mvdata->xcsum);
/* do the actual signature verification */
ret = ksign_verify_signature(sig, sig_size, mvdata->hash);
crypto_free_shash(mvdata->hash->tfm);
kfree(mvdata->hash);
_debug("verify-sig : %d\n", ret);
switch (ret) {
case 0: /* good signature */
*_gpgsig_ok = 1;
break;
case -EKEYREJECTED: /* signature mismatch or number format error */
printk(KERN_ERR "Module signature verification failed\n");
break;
case -ENOKEY: /* signed, but we don't have the public key */
printk(KERN_ERR "Module signed with unknown public key\n");
break;
default: /* other error (probably ENOMEM) */
break;
}
if (ret && badsigok) {
printk(KERN_ERR "Bad signature ignored by cmdline\n");
ret = 0;
}
return ret;
format_error:
crypto_free_shash(mvdata->hash->tfm);
kfree(mvdata->hash);
format_error_no_free:
printk(KERN_ERR "Module format error encountered\n");
return -ELIBBAD;
/* deal with the case of an unsigned module */
no_signature:
_debug("no signature found\n");
if (!signedonly)
return 0;
printk(KERN_ERR "An attempt to load unsigned module was rejected\n");
return -EKEYREJECTED;
}
