Haproxy: ssl_c_sha256

[allentc]

Output of haproxy -vv and uname -a

Re haproxy -vv: N/A - not using haproxy in part due to not having this feature

Linux ip-172-31-23-135.ec2.internal 4.14.121-109.96.amzn2.x86_64 #1 SMP Wed May 22 16:54:10 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

What should haproxy do differently? Which functionality do you think we should add?

Extend layer 5 sample fetch methods; add ssl_c_sha256 as an alternative to ssl_c_sha1. The ever greater weakness of SHA1 should make the need for this self explanatory.

What are you trying to do?

Check client certificates in a proxied application using the DER hash value. Presently using nginx which also can only provide the SHA1 hash value of the client certificate. So I forward the entire client certificate, which is often a rather large and awkward chunk of data to be passing around using headers. Since haproxy can do no better I am not compelled to convert.

[TimWolla]

This adds a converter for the SHA-2 family, supporting SHA-224, SHA-256
SHA-384 and SHA-512.

The converter relies on the OpenSSL implementation, thus only being available
when HAProxy is compiled with USE_OPENSSL.

See GitHub issue #123. The hypothetical ssl_?_sha256 fetch can then be
simulated using ssl_?_der,sha2(256):

http-response set-header Server-Cert-FP %[ssl_f_der,sha2(256),hex]

doc/configuration.txt | 12 ++++++-
reg-tests/converter/sha2.vtc | 60 ++++++++++++++++++++++++++++++++
src/sample.c | 67 ++++++++++++++++++++++++++++++++++++
3 files changed, 138 insertions(+), 1 deletion(-)
create mode 100644 reg-tests/converter/sha2.vtc

diff --git a/doc/configuration.txt b/doc/configuration.txt
index 3e402fb92..2a09bab61 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -14086,9 +14086,19 @@ set-var()
contain characters 'a-z', 'A-Z', '0-9', '.' and '_'.

sha1
- Converts a binary input sample to a SHA1 digest. The result is a binary
+ Converts a binary input sample to a SHA-1 digest. The result is a binary
sample with length of 20 bytes.

+sha2([])

• Converts a binary input sample to a digest in the SHA-2 family. The result
• is a binary sample with length of /8 bytes.
  +
• Valid values for are 224, 256, 384, 512, each corresponding to
• SHA-. The default value is 256.
  +
• Please note that this converter is only available when haproxy has been
• compiled with USE_OPENSSL.
  +
  strcmp()
  Compares the contents of with the input value of type string. Returns
  the result as a signed integer compatible with strcmp(3): 0 if both strings
  diff --git a/reg-tests/converter/sha2.vtc b/reg-tests/converter/sha2.vtc
  new file mode 100644
  index 000000000..0354b0a20
  --- /dev/null
  +++ b/reg-tests/converter/sha2.vtc
  @@ -0,0 +1,60 @@
  +varnishtest "sha2 converter Test"
  +
  +#REQUIRE_VERSION=2.1
  +#REQUIRE_OPTION=OPENSSL
  +
  +feature ignore_unknown_macro
  +
  +server s1 {
• rxreq
• txresp
  +} -repeat 3 -start
  +
  +haproxy h1 -conf {
• defaults
• mode http
• timeout connect 1s
• timeout client 1s
• timeout server 1s
  +
• frontend fe
• bind "fd@${fe}"
  +
• #### requests
• http-request set-var(txn.hash) req.hdr(hash)
  +
• http-response set-header SHA2 "%[var(txn.hash),sha2,hex,lower]"
• http-response set-header SHA2-224 "%[var(txn.hash),sha2(224),hex,lower]"
• http-response set-header SHA2-256 "%[var(txn.hash),sha2(256),hex,lower]"
• http-response set-header SHA2-384 "%[var(txn.hash),sha2(384),hex,lower]"
• http-response set-header SHA2-512 "%[var(txn.hash),sha2(512),hex,lower]"
• http-response set-header SHA2-invalid "%[var(txn.hash),sha2(1),hex,lower]"
  +
• default_backend be
  +
• backend be
• server s1 ${s1_addr}:${s1_port}
  +} -start
  +
  +client c1 -connect ${h1_fe_sock} {
• txreq -url "/" \
• -hdr "Hash: 1"
• rxresp
• expect resp.status == 200
• expect resp.http.sha2 == "6b86b273ff34fce19d6b804eff5a3f5747ada4eaa22f1d49c01e52ddb7875b4b"
• expect resp.http.sha2-224 == "e25388fde8290dc286a6164fa2d97e551b53498dcbf7bc378eb1f178"
• expect resp.http.sha2-256 == "6b86b273ff34fce19d6b804eff5a3f5747ada4eaa22f1d49c01e52ddb7875b4b"
• expect resp.http.sha2-384 == "47f05d367b0c32e438fb63e6cf4a5f35c2aa2f90dc7543f8a41a0f95ce8a40a313ab5cf36134a2068c4c969cb50db776"
• expect resp.http.sha2-512 == "4dff4ea340f0a823f15d3f4f01ab62eae0e5da579ccb851f8db9dfe84c58b2b37b89903a740e1ee172da793a6e79d560e5f7f9bd058a12a280433ed6fa46510a"
• expect resp.http.sha2-invalid == ""
• txreq -url "/" \
• -hdr "Hash: 2"
• rxresp
• expect resp.status == 200
• expect resp.http.sha2 == "d4735e3a265e16eee03f59718b9b5d03019c07d8b6c51f90da3a666eec13ab35"
• expect resp.http.sha2-224 == "58b2aaa0bfae7acc021b3260e941117b529b2e69de878fd7d45c61a9"
• expect resp.http.sha2-256 == "d4735e3a265e16eee03f59718b9b5d03019c07d8b6c51f90da3a666eec13ab35"
• expect resp.http.sha2-384 == "d063457705d66d6f016e4cdd747db3af8d70ebfd36badd63de6c8ca4a9d8bfb5d874e7fbd750aa804dcaddae7eeef51e"
• expect resp.http.sha2-512 == "40b244112641dd78dd4f93b6c9190dd46e0099194d5a44257b7efad6ef9ff4683da1eda0244448cb343aa688f5d3efd7314dafe580ac0bcbf115aeca9e8dc114"
• expect resp.http.sha2-invalid == ""
  +} -run
  diff --git a/src/sample.c b/src/sample.c
  index 67f59e844..96102504b 100644
  --- a/src/sample.c
  +++ b/src/sample.c
  @@ -1537,6 +1537,70 @@ static int sample_conv_sha1(const struct arg *arg_p, struct sample *smp, void *p
  return 1;
  }

+#ifdef USE_OPENSSL
+static int sample_conv_sha2(const struct arg *arg_p, struct sample *smp, void *private)
+{

• struct buffer *trash = get_trash_chunk();
• int bits = 256;
• if (arg_p && arg_p->data.sint)
• bits = arg_p->data.sint;
  +
• switch (bits) {
• case 224: {
• SHA256_CTX ctx;
  +
• memset(&ctx, 0, sizeof(ctx));
  +
• SHA224_Init(&ctx);
• SHA224_Update(&ctx, smp->data.u.str.area, smp->data.u.str.data);
• SHA224_Final((unsigned char *) trash->area, &ctx);
• trash->data = SHA224_DIGEST_LENGTH;
• break;
• }
• case 256: {
• SHA256_CTX ctx;
  +
• memset(&ctx, 0, sizeof(ctx));
  +
• SHA256_Init(&ctx);
• SHA256_Update(&ctx, smp->data.u.str.area, smp->data.u.str.data);
• SHA256_Final((unsigned char *) trash->area, &ctx);
• trash->data = SHA256_DIGEST_LENGTH;
• break;
• }
• case 384: {
• SHA512_CTX ctx;
  +
• memset(&ctx, 0, sizeof(ctx));
  +
• SHA384_Init(&ctx);
• SHA384_Update(&ctx, smp->data.u.str.area, smp->data.u.str.data);
• SHA384_Final((unsigned char *) trash->area, &ctx);
• trash->data = SHA384_DIGEST_LENGTH;
• break;
• }
• case 512: {
• SHA512_CTX ctx;
  +
• memset(&ctx, 0, sizeof(ctx));
  +
• SHA512_Init(&ctx);
• SHA512_Update(&ctx, smp->data.u.str.area, smp->data.u.str.data);
• SHA512_Final((unsigned char *) trash->area, &ctx);
• trash->data = SHA512_DIGEST_LENGTH;
• break;
• }
• default:
• return 0;
• }
  +
• smp->data.u.str = *trash;
• smp->data.type = SMP_T_BIN;
• smp->flags &= ~SMP_F_CONST;
• return 1;
  +}
  +#endif
  +
  static int sample_conv_bin2hex(const struct arg *arg_p, struct sample *smp, void *private)
  {
  struct buffer *trash = get_trash_chunk();
  @@ -3203,6 +3267,9 @@ static struct sample_conv_kw_list sample_conv_kws = {ILH, {
  { "word", sample_conv_word, ARG3(2,SINT,STR,SINT), sample_conv_field_check, SMP_T_STR, SMP_T_STR },
  { "regsub", sample_conv_regsub, ARG3(2,REG,STR,STR), sample_conv_regsub_check, SMP_T_STR, SMP_T_STR },
  { "sha1", sample_conv_sha1, 0, NULL, SMP_T_BIN, SMP_T_BIN },
  +#ifdef USE_OPENSSL
• { "sha2", sample_conv_sha2, ARG1(0, SINT), NULL, SMP_T_BIN, SMP_T_BIN },
  +#endif
  { "concat", sample_conv_concat, ARG3(1,STR,STR,STR), smp_check_concat, SMP_T_STR, SMP_T_STR },
  { "strcmp", sample_conv_strcmp, ARG1(1,STR), smp_check_strcmp, SMP_T_STR, SMP_T_SINT },

--
2.21.0

[TimWolla]

I had expected that email in the collapsed comment to look better. Anyway @allentc I've proposed a patch to add a converter for the SHA-2 family on the mailing list: https://www.mail-archive.com/[email protected]/msg34217.html

Using this converter you would be able to achieve your desired use-case using: http-request set-header Client-Cert %[ssl_c_der,sha2(256),hex].

[TimWolla]

The patch will be included in HAProxy 2.1. I guess it can be trivially applied to 2.0 if you are willing to compile your own HAProxy.

[allentc]

One more haproxy convert! Thank you.

[jeswant]

Can't find documentation related to ssl_c_sha2 in here: https://cbonte.github.io/haproxy-dconv/2.3/configuration.html
in 2.2 configuration documentation. If missing, can we have the fix documented please? Thanks!

[wlallemand]

That's because "ssl_c_sha2" doesn't exist. You have to use ssl_c_der and the sha2 converter like explained by Tim.

https://cbonte.github.io/haproxy-dconv/2.3/configuration.html#ssl_c_der
https://cbonte.github.io/haproxy-dconv/2.3/configuration.html#sha2

[capflam]

Because this sample fetch does not exist. But there is a sha2 converter.