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CMS_decrypt*(): fix misconceptions and mem leak 

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: David von Oheimb <david.von.oheimb@siemens.com>
(Merged from https://github.com/openssl/openssl/pull/19222)
This commit is contained in:
Dr. David von Oheimb 2022-09-15 11:51:30 +02:00 committed by Dr. David von Oheimb
parent 0b7ad5d928
commit 25dd78048b
4 changed files with 51 additions and 31 deletions
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5
crypto/cms/cms_env.c
View File

@ -138,7 +138,7 @@ int ossl_cms_env_asn1_ctrl(CMS_RecipientInfo *ri, int cmd)
return 1;
}
CMS_EncryptedContentInfo* ossl_cms_get0_env_enc_content(const CMS_ContentInfo *cms)
CMS_EncryptedContentInfo *ossl_cms_get0_env_enc_content(const CMS_ContentInfo *cms)
{
switch (cms_get_enveloped_type(cms)) {
case CMS_ENVELOPED_STANDARD:
@ -266,7 +266,8 @@ BIO *CMS_EnvelopedData_decrypt(CMS_EnvelopedData *env, BIO *detached_data,
ASN1_STRING_get0_data(secret),
ASN1_STRING_length(secret)) != 1)
goto end;
res = CMS_decrypt(ci, pkey, cert, detached_data, bio, flags);
res = CMS_decrypt(ci, secret == NULL ? pkey : NULL,
secret == NULL ? cert : NULL, detached_data, bio, flags);
end:
if (ci != NULL)

21
crypto/cms/cms_smime.c
View File

@ -707,10 +707,16 @@ int CMS_decrypt_set1_pkey_and_peer(CMS_ContentInfo *cms, EVP_PKEY *pk,
CMS_RecipientInfo *ri;
int i, r, cms_pkey_ri_type;
int debug = 0, match_ri = 0;
CMS_EncryptedContentInfo *ec = ossl_cms_get0_env_enc_content(cms);
/* Prevent mem leak on earlier CMS_decrypt_set1_{pkey_and_peer,password} */
OPENSSL_clear_free(ec->key, ec->keylen);
ec->key = NULL;
ec->keylen = 0;
ris = CMS_get0_RecipientInfos(cms);
if (ris != NULL)
debug = ossl_cms_get0_env_enc_content(cms)->debug;
debug = ec->debug;
cms_pkey_ri_type = ossl_cms_pkey_get_ri_type(pk);
if (cms_pkey_ri_type == CMS_RECIPINFO_NONE) {
@ -845,7 +851,7 @@ int CMS_decrypt(CMS_ContentInfo *cms, EVP_PKEY *pk, X509 *cert,
{
int r;
BIO *cont;
CMS_EncryptedContentInfo *ec;
int nid = OBJ_obj2nid(CMS_get0_type(cms));
if (nid != NID_pkcs7_enveloped
@ -855,14 +861,9 @@ int CMS_decrypt(CMS_ContentInfo *cms, EVP_PKEY *pk, X509 *cert,
}
if (dcont == NULL && !check_content(cms))
return 0;
if (flags & CMS_DEBUG_DECRYPT)
ossl_cms_get0_env_enc_content(cms)->debug = 1;
else
ossl_cms_get0_env_enc_content(cms)->debug = 0;
if (cert == NULL)
ossl_cms_get0_env_enc_content(cms)->havenocert = 1;
else
ossl_cms_get0_env_enc_content(cms)->havenocert = 0;
ec = ossl_cms_get0_env_enc_content(cms);
ec->debug = (flags & CMS_DEBUG_DECRYPT) != 0;
ec->havenocert = cert == NULL;
if (pk == NULL && cert == NULL && dcont == NULL && out == NULL)
return 1;
if (pk != NULL && !CMS_decrypt_set1_pkey(cms, pk, cert))

12
doc/man3/CMS_EncryptedData_decrypt.pod
View File

@ -26,15 +26,17 @@ to and I<flags> is an optional set of flags.
I<dcont> is used in the rare case where the encrypted content is detached. It
will normally be set to NULL.
The following flags can be passed in the B<flags> parameter.
The following flags can be passed in the I<flags> parameter.
If the B<CMS_TEXT> flag is set MIME headers for type B<text/plain> are deleted
from the content. If the content is not of type B<text/plain> then an error is
If the B<CMS_TEXT> flag is set MIME headers for type C<text/plain> are deleted
from the content. If the content is not of type C<text/plain> then an error is
returned.
CMS_EnvelopedData_decrypt() decrypts, similarly to CMS_decrypt(3),
a CMS EnvelopedData object I<env> using the symmetric key I<secret> or
the private key of the recipient B<pkey> and its associated certificate B<cert>.
a CMS EnvelopedData object I<env> using the symmetric key I<secret> if it
is not NULL, otherwise the private key of the recipient I<pkey>.
If I<pkey> is given, it is recommended to provide also the associated
certificate in I<cert> - see L<CMS_decrypt(3)> and the NOTES on I<cert> there.
The optional parameters I<flags> and I<dcont> are used as described above.
The optional parameters library context I<libctx> and property query I<propq>
are used when retrieving algorithms from providers.

44
doc/man3/CMS_decrypt.pod
View File

@ -20,23 +20,35 @@ CMS_decrypt_set1_pkey, CMS_decrypt_set1_password
=head1 DESCRIPTION
CMS_decrypt() extracts and decrypts the content from a CMS EnvelopedData
or AuthEnvelopedData structure. I<pkey> is the private key of the recipient,
I<cert> is the recipient's certificate, I<out> is a BIO to write the content to
and I<flags> is an optional set of flags.
CMS_decrypt() extracts the decrypted content from a CMS EnvelopedData
or AuthEnvelopedData structure.
It uses CMS_decrypt_set1_pkey() to decrypt the content
with the recipient private key I<pkey> if I<pkey> is not NULL.
In this case, the associated certificate is recommended to provide in I<cert> -
see the NOTES below.
I<out> is a BIO to write the content to and
I<flags> is an optional set of flags.
If I<pkey> is NULL the function assumes that decryption was already done
(e.g., using CMS_decrypt_set1_pkey() or CMS_decrypt_set1_password()) and just
provides the content unless I<cert>, I<dcont>, and I<out> are NULL as well.
The I<dcont> parameter is used in the rare case where the encrypted content
is detached. It will normally be set to NULL.
CMS_decrypt_set1_pkey_and_peer() associates the private key I<pkey>, the
corresponding certificate I<cert> and the originator certificate I<peer> with
the CMS_ContentInfo structure I<cms>.
CMS_decrypt_set1_pkey_and_peer() decrypts the CMS_ContentInfo structure I<cms>
using the private key I<pkey>, the corresponding certificate I<cert>, which is
recommended but may be NULL, and the (optional) originator certificate I<peer>.
On success, it also records in I<cms> the decryption key I<pkey>, and then
should be followed by C<CMS_decrypt(cms, NULL, NULL, dcont, out, flags)>.
This call deallocates any decryption key stored in I<cms>.
CMS_decrypt_set1_pkey() associates the private key I<pkey> and the corresponding
certificate I<cert> with the CMS_ContentInfo structure I<cms>.
CMS_decrypt_set1_pkey() is the same as
CMS_decrypt_set1_pkey_and_peer() with I<peer> being NULL.
CMS_decrypt_set1_password() associates the secret I<pass> of length I<passlen>
with the CMS_ContentInfo structure I<cms>.
CMS_decrypt_set1_password() decrypts the CMS_ContentInfo structure I<cms>
using the secret I<pass> of length I<passlen>.
On success, it also records in I<cms> the decryption key used, and then
should be followed by C<CMS_decrypt(cms, NULL, NULL, dcont, out, flags)>.
This call deallocates any decryption key stored in I<cms>.
=head1 NOTES
@ -60,8 +72,9 @@ open to attack.
It is possible to determine the correct recipient key by other means (for
example looking them up in a database) and setting them in the CMS structure
in advance using the CMS utility functions such as CMS_set1_pkey(). In this
case both I<cert> and I<pkey> should be set to NULL.
in advance using the CMS utility functions such as CMS_set1_pkey(),
or use CMS_decrypt_set1_password() if the recipient has a symmetric key.
In these cases both I<cert> and I<pkey> should be set to NULL.
To process KEKRecipientInfo types CMS_set1_key() or CMS_RecipientInfo_set0_key()
and CMS_RecipientInfo_decrypt() should be called before CMS_decrypt() and
@ -82,6 +95,9 @@ The error can be obtained from ERR_get_error(3).
=head1 BUGS
The B<set1_> part of these function names is misleading
and should better read: B<with_>.
The lack of single pass processing and the need to hold all data in memory as
mentioned in CMS_verify() also applies to CMS_decrypt().