David Coppa <dco...@gmail.com> writes:
> On Wed, 03 Aug 2016, Stuart Henderson wrote:
>
>> On 2016/08/03 12:10, Stuart Henderson wrote:
>> > On 2016/07/30 17:04, Giovanni Bechis wrote:
>> > > On Sat, Jul 30, 2016 at 11:57:14AM +0100, Stuart Henderson wrote:
>> > > > Forwarding from an offlist message because incoming mail is broken..
>> > > >
>> > > no problem for me, just renewed my certificate with
>> > > authenticator=standalone @i386 (OpenBSD 6.0 (GENERIC) #1915: Tue Jul 26
>> > > 09:46:01 MDT 2016)
>> > > Have you added wxallowed in fstab(5) ?
>> >
>> > So wxallowed is required for this; it turns out that this is
>> > due to devel/py-cffi. py-cffi does an mmap which is currently
>> > RWX unless it detects PaX on Linux in which case it changes
>> > it to RW. But if I change things to permit that, we run into
>> > another problem: the library using py-cffi in this case is
>> > py-cryptography, which calls out to libcrypto, and it segfaults
>> > after doing so:
>> >
>> > (gdb) bt
>> > #0 0x000003d6f2169fc0 in ?? ()
>> > #1 0x000003d6bef3ba4c in internal_verify (ctx=0x7f7ffffe4eb0)
>> > at
>> > /usr/src/lib/libcrypto/crypto/../../libssl/src/crypto/x509/x509_vfy.c:1611
>> > #2 0x000003d6bef3d109 in X509_verify_cert (ctx=0x7f7ffffe4eb0)
>> > at
>> > /usr/src/lib/libcrypto/crypto/../../libssl/src/crypto/x509/x509_vfy.c:374
>> > #3 0x000003d78b79c8f0 in ssl_verify_cert_chain (s=0x3d6c5708000,
>> > sk=Variable "sk" is not available.
>> > )
>> > at /usr/src/lib/libssl/ssl/../../libssl/src/ssl/ssl_cert.c:448
>> > #4 0x000003d78b78c030 in ssl3_get_server_certificate (s=0x3d6c5708000)
>> > at /usr/src/lib/libssl/ssl/../../libssl/src/ssl/s3_clnt.c:1015
>> > #5 0x000003d78b78d421 in ssl3_connect (s=0x3d6c5708000)
>> > at /usr/src/lib/libssl/ssl/../../libssl/src/ssl/s3_clnt.c:297
>> > #6 0x000003d78b794c4e in ssl23_connect (s=0x3d6c5708000)
>> > at /usr/src/lib/libssl/ssl/../../libssl/src/ssl/s23_clnt.c:477
>> > #7 0x000003d78a76f08c in _cffi_f_SSL_do_handshake ()
>> > from
>> > /usr/local/lib/python2.7/site-packages/cryptography/hazmat/bindings/_openssl.so
>> > #8 0x000003d70659d528 in PyEval_EvalFrameEx ()
>> > from /usr/local/lib/libpython2.7.so.0.0
>> > #9 0x000003d70659d2ea in PyEval_EvalFrameEx ()
>> > from /usr/local/lib/libpython2.7.so.0.0
>> > #10 0x000003d70659f33d in PyEval_EvalCodeEx ()
>> >
>> > 1604 ok = x509_check_cert_time(ctx, xs, 0);
>> > 1605 if (!ok)
>> > 1606 goto end;
>> > 1607
>> > 1608 /* The last error (if any) is still in the error
>> > value */
>> > 1609 ctx->current_issuer = xi;
>> > 1610 ctx->current_cert = xs;
>> > 1611 ok = (*cb)(1, ctx);
>> > 1612 if (!ok)
>> > 1613 goto end;
>> >
>> > At the moment I don't have any ideas other than "mark /usr/local
>> > as wxallowed if you want to run things using py-cffi". Can anyone
>> > think of something better?
>> >
>>
>> Here are some more prints from another run of this (this segfault
>> is occurring with py-cffi patched to just do RW mappings; it occurs
>> whether or not the partition is marked wxallowed).
>>
>> I can't do any more digging until next week.
>>
>> (gdb) bt
>> #0 0x00001207405f1fc0 in ?? ()
>> #1 0x00001206b3377a4c in internal_verify (ctx=0x7f7ffffeaae0)
>> at
>> /usr/src/lib/libcrypto/crypto/../../libssl/src/crypto/x509/x509_vfy.c:1611
>> #2 0x00001206b3379109 in X509_verify_cert (ctx=0x7f7ffffeaae0)
>> at
>> /usr/src/lib/libcrypto/crypto/../../libssl/src/crypto/x509/x509_vfy.c:374
>> #3 0x00001206d2eff8f0 in ssl_verify_cert_chain (s=0x120700f1c000,
>> sk=Variable "sk" is not available.
>> )
>> at /usr/src/lib/libssl/ssl/../../libssl/src/ssl/ssl_cert.c:448
>> #4 0x00001206d2eef030 in ssl3_get_server_certificate (s=0x120700f1c000)
>> at /usr/src/lib/libssl/ssl/../../libssl/src/ssl/s3_clnt.c:1015
>> #5 0x00001206d2ef0421 in ssl3_connect (s=0x120700f1c000)
>> at /usr/src/lib/libssl/ssl/../../libssl/src/ssl/s3_clnt.c:297
>> #6 0x00001206d2ef7c4e in ssl23_connect (s=0x120700f1c000)
>> at /usr/src/lib/libssl/ssl/../../libssl/src/ssl/s23_clnt.c:477
>> #7 0x00001206dca5a44f in _cffi_f_SSL_do_handshake (self=0x1206c2cf7dc0,
>> arg0=0x1206b5421650)
>> at
>> /usr/obj/ports/py-cryptography-1.4/cryptography-1.4/temp.openbsd-6.0-amd64-2.7/_openssl.c:51236
>> #8 0x0000120731c1a528 in PyEval_EvalFrameEx () from
>> /usr/local/lib/libpython2.7.so.0.0
>> #9 0x0000120731c1a2ea in PyEval_EvalFrameEx () from
>> /usr/local/lib/libpython2.7.so.0.0
>> [..]
>> #38 0x0000120731c1c33d in PyEval_EvalCodeEx () from
>> /usr/local/lib/libpython2.7.so.0.0
>> #39 0x0000120731ba3bf7 in function_call () from
>> /usr/local/lib/libpython2.7.so.0.0
>> #40 0x0000120731b79cc8 in PyObject_Call () from
>> /usr/local/lib/libpython2.7.so.0.0
>> #41 0x0000120731b88f92 in instancemethod_call () from
>> /usr/local/lib/libpython2.7.so.0.0
>> [..]
>> (gdb) frame 1
>> #1 0x00001206b3377a4c in internal_verify (ctx=0x7f7ffffeaae0)
>> at
>> /usr/src/lib/libcrypto/crypto/../../libssl/src/crypto/x509/x509_vfy.c:1611
>> 1611 ok = (*cb)(1, ctx);
>> (gdb) p *ctx
>> $1 = {ctx = 0x1206c17c4d00, current_method = 0, cert = 0x12067c8ab600,
>> untrusted = 0x1206c17ca8c0, crls = 0x0,
>> param = 0x120753e79540, other_ctx = 0x0, verify = 0x1206b3377940
>> <internal_verify>, verify_cb = 0x1207405f1fc0,
>> get_issuer = 0x1206b333f890 <X509_STORE_CTX_get1_issuer>, check_issued =
>> 0x1206b3377240 <check_issued>,
>> check_revocation = 0x1206b3378490 <check_revocation>, get_crl = 0,
>> check_crl = 0x1206b3379220 <check_crl>,
>> cert_crl = 0x1206b3377070 <cert_crl>, check_policy = 0x1206b3376f10
>> <check_policy>,
>> lookup_certs = 0x1206b333fd10 <X509_STORE_get1_certs>, lookup_crls =
>> 0x1206b333fb10 <X509_STORE_get1_crls>,
>> cleanup = 0, valid = 0, last_untrusted = 3, chain = 0x1206a6a5c860, tree =
>> 0x0, explicit_policy = 0,
>> error_depth = 3, error = 0, current_cert = 0x1206d841ae00, current_issuer
>> = 0x1206d841ae00, current_crl = 0x0,
>> current_crl_score = 0, current_reasons = 0, parent = 0x0, ex_data = {sk =
>> 0x1206a6a5ca00}}
>> (gdb) list
>> 1606 goto end;
>> 1607
>> 1608 /* The last error (if any) is still in the error value
>> */
>> 1609 ctx->current_issuer = xi;
>> 1610 ctx->current_cert = xs;
>> 1611 ok = (*cb)(1, ctx);
>> 1612 if (!ok)
>> 1613 goto end;
>> 1614
>> 1615 n--;
>> (gdb) p *ctx->cert
>> $2 = {cert_info = 0x120738043f80, sig_alg = 0x1206fd9518f0, signature =
>> 0x1206881396c0, valid = 0, references = 2,
>> name = 0x1206de46cc00 "/CN=*.api.letsencrypt.org/O=INTERNET SECURITY
>> RESEARCH GROUP/L=Mountain View/ST=California/C=US", ex_data = {sk = 0x0},
>> ex_pathlen = -1, ex_pcpathlen = 0, ex_flags = 262, ex_kusage = 160,
>> ex_xkusage = 3,
>> ex_nscert = 0, skid = 0x1206a6a5cd20, akid = 0x120699a98880, policy_cache
>> = 0x0, crldp = 0x12068875b3a0,
>> altname = 0x12068875b0a0, nc = 0x0, sha1_hash =
>> "?[i?\205@???\a?O?\v??1B\022?", aux = 0x0}
>> (gdb) p cb
>> $3 = (int (*)(int, X509_STORE_CTX *)) 0x1207405f1fc0
>>
>> So it's trying to call 0x1207405f1fc0 which is the function pointer
>> stored in verify_cb.
>
> The problem is in py-openssl, which is still using dynamic ffi
> callbacks, causing W^X violations.
>
> The diff below (adapted from an unmerged branch of py-cffi) makes
> letsencrypt work for me.
Looks fine to me and works fine on i386, ok jca@
> https://bitbucket.org/cffi/cffi/issues/231/writeable-memory-execution-execmem-with
>
> https://github.com/pyca/cryptography/issues/2477
>
> https://bugzilla.redhat.com/show_bug.cgi?id=1249685
>
> Ciao!
> David
>
> P.S.: I know this implementation has problems wrt fork()
> (https://bugs.python.org/issue25653), but given that we already
> took this road with devel/libffi rev 1.35...
> The example code from https://bugzilla.redhat.com/show_bug.cgi?id=531233
> is already crashing for us.
:(
--
jca | PGP: 0x1524E7EE / 5135 92C1 AD36 5293 2BDF DDCC 0DFA 74AE 1524 E7EE
