Refactor tls code to support ucspi-tls

 That includes:
 - new architecture: the tls binary is now a child of the app
instead of the other way around
 - the sbearssl_run engine now takes a post-handshake callback.
This allows s6-tlsc and s6-tlsd to only exec into the app when
the handshake succeeds (which was already the case with libressl).
 - new binaries s6-tlsc-io and s6-tlsd-io encapsulate the crypto
code; they init and run the engine, connecting to 4 already open
fds (stdin/stdout = network, argv[1] and argv[2] = local)
 - s6-tlsc is now a simple wrapper around s6-tlsc-io
 - s6-tlsd is now a simple wrapper around s6-tlsd-io
 - new binary: s6-ucspitlsd, which is also a wrapper around
s6-tlsd-io, but differently: the parent execs the app which should
be ucspi-tls-aware, the child waits for a command from the parent
and execs into s6-tlsd-io if it receives it.

1 files changed, 24 insertions, 0 deletions

diff --git a/src/conn-tools/s6tls_drop.c b/src/conn-tools/s6tls_drop.c
new file mode 100644
index 0000000..6b6f67f
--- /dev/null
+++ b/src/conn-tools/s6tls_drop.c
@@ -0,0 +1,24 @@
+/* ISC license. */
+
+#include <unistd.h>
+#include <stdlib.h>
+
+#include <skalibs/strerr2.h>
+#include <skalibs/types.h>
+
+#include "s6tls-internal.h"
+
+void s6tls_drop (void)
+{
+  if (!getuid())
+  {
+    uid_t uid ;
+    gid_t gid ;
+    char const *x = getenv("TLS_UID") ;
+    if (x && !uid0_scan(x, &uid)) strerr_dieinvalid(100, "TLS_UID") ;
+    x = getenv("TLS_GID") ;
+    if (x && !gid0_scan(x, &gid)) strerr_dieinvalid(100, "TLS_GID") ;
+    if (gid && setgid(gid) < 0) strerr_diefu1sys(111, "setgid") ;
+    if (uid && setuid(uid) < 0) strerr_diefu1sys(111, "setuid") ;
+  }
+}