pkcs7: add PKCS7_NO_DUAL_CONTENT flag/behavior

What Netscape fucked up just had to be embraced by secure boot and
other nonsense. First OpenSSL wanted to be strict (which we inherited)
then Rich Salz Postel-ized this and made OpenSSL bypass this check by
default and added a flag to be strict 10 years ago.

Now sthen found that PHP 8.5 uses/exposes this flag.

Follows OpenSSL 6b2ebe43 (2016)

ok kenjiro

1 files changed, 11 insertions, 2 deletions

diff --git a/src/lib/libcrypto/man/PKCS7_verify.3 b/src/lib/libcrypto/man/PKCS7_verify.3
index 6bf932b54b..53b32f738a 100644
--- a/src/lib/libcrypto/man/PKCS7_verify.3
+++ b/src/lib/libcrypto/man/PKCS7_verify.3
@@ -1,4 +1,4 @@
-.\"     $OpenBSD: PKCS7_verify.3,v 1.12 2025/06/08 22:40:30 schwarze Exp $
+.\"     $OpenBSD: PKCS7_verify.3,v 1.13 2025/12/20 07:22:43 tb Exp $
 .\"     OpenSSL a528d4f0 Oct 27 13:40:11 2015 -0400
 .\"
 .\" This file was written by Dr. Stephen Henson <steve@openssl.org>.
@@ -48,7 +48,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 .\" OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: June 8 2025 $
+.Dd $Mdocdate: December 20 2025 $
 .Dt PKCS7_VERIFY 3
 .Os
 .Sh NAME
@@ -125,6 +125,15 @@ is detached,
 .Fa indata
 cannot be
 .Dv NULL .
+If the content is not detached and
+.Fa indata
+is not
+.Fa NULL ,
+then the structure has both embedded and external content.
+To treat this as an error, use the flag
+.Dv PKCS7_NO_DUAL_CONTENT .
+The default behavior allows this, for compatibility with other
+implementations.
 .Pp
 An attempt is made to locate all the signer's certificates, first
 looking in the