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crypto: sig - Fix oops on KEYCTL_PKEY_QUERY for RSA keys

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Commit a2471684da ("crypto: ecdsa - Move X9.62 signature size
calculation into template") introduced ->max_size() and ->digest_size()
callbacks to struct sig_alg.  They return an algorithm's maximum
signature size and digest size, respectively.

For algorithms which lack these callbacks, crypto_register_sig() was
amended to use the ->key_size() callback instead.

However the commit neglected to also amend sig_register_instance().
As a result, the ->max_size() and ->digest_size() callbacks remain NULL
pointers if instances do not define them.  A KEYCTL_PKEY_QUERY system
call results in an oops for such instances:

  BUG: kernel NULL pointer dereference, address: 0000000000000000
  Call Trace:
  software_key_query+0x169/0x370
  query_asymmetric_key+0x67/0x90
  keyctl_pkey_query+0x86/0x120
  __do_sys_keyctl+0x428/0x480
  do_syscall_64+0x4b/0x110

The only instances affected by this are "pkcs1(rsa, ...)".

Fix by moving the callback checks from crypto_register_sig() to
sig_prepare_alg(), which is also invoked by sig_register_instance().
Change the return type of sig_prepare_alg() from void to int to be able
to return errors.  This matches other algorithm types, see e.g.
aead_prepare_alg() or ahash_prepare_alg().

Fixes: a2471684da ("crypto: ecdsa - Move X9.62 signature size calculation into template")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Lukas Wunner 2024-10-14 11:43:01 +02:00 committed by Herbert Xu
parent 84dd048cf8
commit b358f23ab1
1 changed files with 24 additions and 12 deletions
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36
crypto/sig.c
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@ -84,15 +84,6 @@ struct crypto_sig *crypto_alloc_sig(const char *alg_name, u32 type, u32 mask)
}
EXPORT_SYMBOL_GPL(crypto_alloc_sig);
static void sig_prepare_alg(struct sig_alg *alg)
{
struct crypto_alg *base = &alg->base;
base->cra_type = &crypto_sig_type;
base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
base->cra_flags |= CRYPTO_ALG_TYPE_SIG;
}
static int sig_default_sign(struct crypto_sig *tfm,
const void *src, unsigned int slen,
void *dst, unsigned int dlen)
@ -113,7 +104,7 @@ static int sig_default_set_key(struct crypto_sig *tfm,
return -ENOSYS;
}
int crypto_register_sig(struct sig_alg *alg)
static int sig_prepare_alg(struct sig_alg *alg)
{
struct crypto_alg *base = &alg->base;
@ -132,7 +123,22 @@ int crypto_register_sig(struct sig_alg *alg)
if (!alg->digest_size)
alg->digest_size = alg->key_size;
sig_prepare_alg(alg);
base->cra_type = &crypto_sig_type;
base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
base->cra_flags |= CRYPTO_ALG_TYPE_SIG;
return 0;
}
int crypto_register_sig(struct sig_alg *alg)
{
struct crypto_alg *base = &alg->base;
int err;
err = sig_prepare_alg(alg);
if (err)
return err;
return crypto_register_alg(base);
}
EXPORT_SYMBOL_GPL(crypto_register_sig);
@ -146,9 +152,15 @@ EXPORT_SYMBOL_GPL(crypto_unregister_sig);
int sig_register_instance(struct crypto_template *tmpl,
struct sig_instance *inst)
{
int err;
if (WARN_ON(!inst->free))
return -EINVAL;
sig_prepare_alg(&inst->alg);
err = sig_prepare_alg(&inst->alg);
if (err)
return err;
return crypto_register_instance(tmpl, sig_crypto_instance(inst));
}
EXPORT_SYMBOL_GPL(sig_register_instance);