Merge branch 'jc/push-cert'

The "git push --signed" protocol extension did not limit what the
"nonce" that is a server-chosen string can contain or how long it
can be, which was unnecessarily lax.  Limit both the length and the
alphabet to a reasonably small space that can still have enough
entropy.

* jc/push-cert:
  push --signed: tighten what the receiving end can ask to sign
This commit is contained in:
Junio C Hamano 2015-04-20 15:28:31 -07:00
commit 268d5bc2b2

View File

@ -308,6 +308,28 @@ static int atomic_push_failure(struct send_pack_args *args,
failing_ref->name, failing_ref->status);
}
#define NONCE_LEN_LIMIT 256
static void reject_invalid_nonce(const char *nonce, int len)
{
int i = 0;
if (NONCE_LEN_LIMIT <= len)
die("the receiving end asked to sign an invalid nonce <%.*s>",
len, nonce);
for (i = 0; i < len; i++) {
int ch = nonce[i] & 0xFF;
if (isalnum(ch) ||
ch == '-' || ch == '.' ||
ch == '/' || ch == '+' ||
ch == '=' || ch == '_')
continue;
die("the receiving end asked to sign an invalid nonce <%.*s>",
len, nonce);
}
}
int send_pack(struct send_pack_args *args,
int fd[], struct child_process *conn,
struct ref *remote_refs,
@ -354,6 +376,7 @@ int send_pack(struct send_pack_args *args,
push_cert_nonce = server_feature_value("push-cert", &len);
if (!push_cert_nonce)
die(_("the receiving end does not support --signed push"));
reject_invalid_nonce(push_cert_nonce, len);
push_cert_nonce = xmemdupz(push_cert_nonce, len);
}