Fix case where s6-tls[cd] would sometimes not detect an application and remain there forever with its zombie, both condemned to err in limbo for all eternity, the living and the dead, hand in hand

7 files changed, 106 insertions, 77 deletions

diff --git a/src/sbearssl/deps-lib/sbearssl b/src/sbearssl/deps-lib/sbearssl
index 4945ad8..c0acfb6 100644
--- a/src/sbearssl/deps-lib/sbearssl
+++ b/src/sbearssl/deps-lib/sbearssl
@@ -1,5 +1,5 @@
 sbearssl_append.o
-sbearssl_clean_tls_and_spawn.o
+sbearssl_prep_spawn_drop.o
 sbearssl_cert_from.o
 sbearssl_cert_readbigpem.o
 sbearssl_cert_readfile.o
diff --git a/src/sbearssl/sbearssl-internal.h b/src/sbearssl/sbearssl-internal.h
index df3e3e5..cbf355b 100644
--- a/src/sbearssl/sbearssl-internal.h
+++ b/src/sbearssl/sbearssl-internal.h
@@ -19,6 +19,6 @@ struct sbearssl_strallocerr_s
 
 extern void sbearssl_append (void *, void const *, size_t) ;
 extern int sbearssl_pem_push (br_pem_decoder_context *, char const *, size_t, sbearssl_pemobject *, genalloc *, sbearssl_strallocerr *, int *) ;
-extern pid_t sbearssl_clean_tls_and_spawn (char const *const *, char const *const *, int *, uint32_t) ;
+extern pid_t sbearssl_prep_spawn_drop (char const *const *, char const *const *, int *, uid_t, gid_t, uint32_t) ;
 
 #endif
diff --git a/src/sbearssl/sbearssl_clean_tls_and_spawn.c b/src/sbearssl/sbearssl_clean_tls_and_spawn.c
deleted file mode 100644
index 258db90..0000000
--- a/src/sbearssl/sbearssl_clean_tls_and_spawn.c
+++ /dev/null
@@ -1,21 +0,0 @@
-/* ISC license. */
-
-#include <sys/types.h>
-#include <skalibs/env.h>
-#include <skalibs/djbunix.h>
-#include "sbearssl-internal.h"
-
-pid_t sbearssl_clean_tls_and_spawn (char const *const *argv, char const *const *envp, int *fds, uint32_t options)
-{
-  if (!(options & 1)) return child_spawn2(argv[0], argv, envp, fds) ;
-  else
-  {
-    char const modifs[] = "CADIR\0CAFILE\0KEYFILE\0CERTFILE\0TLS_UID\0TLS_GID" ;
-    size_t modiflen = sizeof(modifs) ;
-    size_t n = env_len(envp) ;
-    char const *newenv[n + 7] ;
-    size_t newenvlen = env_merge(newenv, n+7, envp, n, modifs, modiflen) ;
-    if (!newenvlen) return 0 ;
-    return child_spawn2(argv[0], argv, newenv, fds) ;
-  }
-}
diff --git a/src/sbearssl/sbearssl_prep_spawn_drop.c b/src/sbearssl/sbearssl_prep_spawn_drop.c
new file mode 100644
index 0000000..1ca7eb8
--- /dev/null
+++ b/src/sbearssl/sbearssl_prep_spawn_drop.c
@@ -0,0 +1,35 @@
+/* ISC license. */
+
+#include <unistd.h>
+#include <signal.h>
+#include <skalibs/env.h>
+#include <skalibs/strerr2.h>
+#include <skalibs/djbunix.h>
+#include <skalibs/selfpipe.h>
+#include "sbearssl-internal.h"
+
+pid_t sbearssl_prep_spawn_drop (char const *const *argv, char const *const *envp, int *fds, uid_t uid, gid_t gid, uint32_t options)
+{
+  pid_t pid ;
+
+  fds[4] = selfpipe_init() ;
+  if (fds[4] < 0) strerr_diefu1sys(111, "init selfpipe") ;
+  if (selfpipe_trap(SIGCHLD) < 0) strerr_diefu1sys(111, "trap SIGCHLD") ;
+
+  if (!(options & 1)) pid = child_spawn2(argv[0], argv, envp, fds) ;
+  else
+  {
+    char const modifs[] = "CADIR\0CAFILE\0KEYFILE\0CERTFILE\0TLS_UID\0TLS_GID" ;
+    size_t modiflen = sizeof(modifs) ;
+    size_t n = env_len(envp) ;
+    char const *newenv[n + 7] ;
+    size_t newenvlen = env_merge(newenv, n+7, envp, n, modifs, modiflen) ;
+    if (!newenvlen) return 0 ;
+    pid = child_spawn2(argv[0], argv, newenv, fds) ;
+  }
+
+  if (!pid) strerr_diefu2sys(111, "spawn ", argv[0]) ;
+  if (gid && setgid(gid) < 0) strerr_diefu1sys(111, "setgid") ;
+  if (uid && setuid(uid) < 0) strerr_diefu1sys(111, "setuid") ;
+  return pid ;
+}
diff --git a/src/sbearssl/sbearssl_run.c b/src/sbearssl/sbearssl_run.c
index ca4a79e..26a8bd3 100644
--- a/src/sbearssl/sbearssl_run.c
+++ b/src/sbearssl/sbearssl_run.c
@@ -1,7 +1,6 @@
 /* ISC license. */
 
 #include <skalibs/nonposix.h>
-#include <sys/types.h>
 #include <sys/socket.h>
 #include <errno.h>
 #include <signal.h>
@@ -12,13 +11,33 @@
 #include <skalibs/tai.h>
 #include <skalibs/iopause.h>
 #include <skalibs/djbunix.h>
+#include <skalibs/selfpipe.h>
 #include <s6-networking/sbearssl.h>
 
-int sbearssl_run (br_ssl_engine_context *ctx, int *fds, unsigned int verbosity, uint32_t options, tain_t const *tto)
+static inline void handle_signals (pid_t pid, int *e)
 {
-  iopause_fd x[4] ;
+  for (;;) switch (selfpipe_read())
+  {
+    case -1 : strerr_diefu1sys(111, "read selfpipe") ;
+    case 0 : return ;
+    case SIGCHLD :
+    {
+      int wstat ;
+      if (wait_pid_nohang(pid, &wstat) == pid)
+      {
+        *e = wstat ;
+        return ;
+      }
+    }
+  }
+}
+
+int sbearssl_run (br_ssl_engine_context *ctx, int *fds, pid_t pid, unsigned int verbosity, uint32_t options, tain_t const *tto)
+{
+  iopause_fd x[5] = { { .fd = fds[4], .events = IOPAUSE_READ } } ;
   unsigned int xindex[4] ;
   int markedforflush = 0 ;
+  int e = -1 ;
 
   if (ndelay_on(fds[2]) < 0 || ndelay_on(fds[3]) < 0)
     strerr_diefu1sys(111, "set fds non-blocking") ;
@@ -28,11 +47,16 @@ int sbearssl_run (br_ssl_engine_context *ctx, int *fds, unsigned int verbosity,
   for (;;)
   {
     tain_t deadline ;
-    unsigned int j = 0 ;
+    unsigned int j = 1 ;
     unsigned int state = br_ssl_engine_current_state(ctx) ;
     int r ;
 
-    if (state & BR_SSL_CLOSED) break ;
+    if (state & BR_SSL_CLOSED)
+    {
+      r = br_ssl_engine_last_error(ctx) ;
+      if (r) strerr_diefu2x(98, "establish or maintain SSL connection to peer: ", sbearssl_error_str(r)) ;
+      break ;
+    }
 
     tain_add_g(&deadline, fds[0] >= 0 && fds[2] >= 0 && state & (BR_SSL_SENDAPP | BR_SSL_RECVREC) ? tto : &tain_infinite_relative) ;
 
@@ -42,30 +66,30 @@ int sbearssl_run (br_ssl_engine_context *ctx, int *fds, unsigned int verbosity,
       x[j].events = IOPAUSE_READ ;
       xindex[0] = j++ ;
     }
-    else xindex[0] = 4 ;
+    else xindex[0] = 5 ;
     if (fds[1] >= 0 && state & BR_SSL_RECVAPP)
     {
       x[j].fd = fds[1] ;
       x[j].events = IOPAUSE_WRITE ;
       xindex[1] = j++ ;
     }
-    else xindex[1] = 4 ;
+    else xindex[1] = 5 ;
     if (fds[2] >= 0 && state & BR_SSL_RECVREC)
     {
       x[j].fd = fds[2] ;
       x[j].events = IOPAUSE_READ ;
       xindex[2] = j++ ;
     }
-    else xindex[2] = 4 ;
+    else xindex[2] = 5 ;
     if (fds[3] >= 0 && state & BR_SSL_SENDREC)
     {
       x[j].fd = fds[3] ;
       x[j].events = IOPAUSE_WRITE ;
       xindex[3] = j++ ;
     }
-    else xindex[3] = 4 ;
+    else xindex[3] = 5 ;
 
-    if (!j) break ;
+    if (j == 1) break ;
     r = iopause_g(x, j, &deadline) ;
     if (r < 0) strerr_diefu1sys(111, "iopause") ;
     else if (!r)
@@ -77,6 +101,7 @@ int sbearssl_run (br_ssl_engine_context *ctx, int *fds, unsigned int verbosity,
         fd_close(fds[3]) ; fds[3] = -1 ;
       }
       else br_ssl_engine_close(ctx) ;
+      if (e >= 0) break ;
       continue ;
     }
 
@@ -85,6 +110,11 @@ int sbearssl_run (br_ssl_engine_context *ctx, int *fds, unsigned int verbosity,
         x[j].revents |= IOPAUSE_READ | IOPAUSE_WRITE ;
 
 
+   /* Signal */
+
+    if (x[0].revents & IOPAUSE_READ) handle_signals(pid, &e) ;
+
+
    /* Flush to local */
 
     if (state & BR_SSL_RECVAPP && x[xindex[1]].events & x[xindex[1]].revents & IOPAUSE_WRITE)
@@ -111,7 +141,7 @@ int sbearssl_run (br_ssl_engine_context *ctx, int *fds, unsigned int verbosity,
 
    /* Flush to remote */
 
-    if (state & BR_SSL_SENDREC && x[xindex[3]].events & x[xindex[3]].revents & IOPAUSE_WRITE)
+    if (state & BR_SSL_SENDREC && xindex[3] < 5 && x[xindex[3]].events & x[xindex[3]].revents & IOPAUSE_WRITE)
     {
       size_t len ;
       unsigned char const *s = br_ssl_engine_sendrec_buf(ctx, &len) ;
@@ -132,6 +162,7 @@ int sbearssl_run (br_ssl_engine_context *ctx, int *fds, unsigned int verbosity,
             fd_close(fds[3]) ; fds[3] = -1 ;
           }
           else br_ssl_engine_close(ctx) ;
+          if (e >= 0) break ;
         }
         state = br_ssl_engine_current_state(ctx) ;
       }
@@ -140,7 +171,7 @@ int sbearssl_run (br_ssl_engine_context *ctx, int *fds, unsigned int verbosity,
 
    /* Fill from local */
 
-    if (state & BR_SSL_SENDAPP && x[xindex[0]].events & IOPAUSE_READ && (markedforflush || x[xindex[0]].revents & IOPAUSE_READ))
+    if (state & BR_SSL_SENDAPP && xindex[0] < 5 && x[xindex[0]].events & IOPAUSE_READ && (markedforflush || x[xindex[0]].revents & IOPAUSE_READ))
     {
       size_t len ;
       unsigned char *s = br_ssl_engine_sendapp_buf(ctx, &len) ;
@@ -160,6 +191,7 @@ int sbearssl_run (br_ssl_engine_context *ctx, int *fds, unsigned int verbosity,
               fd_close(fds[3]) ; fds[3] = -1 ;
             }
             else br_ssl_engine_close(ctx) ;
+            if (e >= 0) break ;
           }
         }
       }
@@ -179,7 +211,7 @@ int sbearssl_run (br_ssl_engine_context *ctx, int *fds, unsigned int verbosity,
 
    /* Fill from remote */
 
-    if (state & BR_SSL_RECVREC && x[xindex[2]].events & x[xindex[2]].revents & IOPAUSE_READ)
+    if (state & BR_SSL_RECVREC && xindex[2] < 5 && x[xindex[2]].events & x[xindex[2]].revents & IOPAUSE_READ)
     {
       size_t len ;
       unsigned char *s = br_ssl_engine_recvrec_buf(ctx, &len) ;
@@ -204,5 +236,5 @@ int sbearssl_run (br_ssl_engine_context *ctx, int *fds, unsigned int verbosity,
   if (fds[0] >= 0) fd_close(fds[0]) ;
   if (fds[3] >= 0) fd_close(fds[3]) ;
   if (fds[2] >= 0) fd_close(fds[2]) ;
-  return br_ssl_engine_last_error(ctx) ;
+  return e ;
 }
diff --git a/src/sbearssl/sbearssl_s6tlsc.c b/src/sbearssl/sbearssl_s6tlsc.c
index e01e25e..267d79c 100644
--- a/src/sbearssl/sbearssl_s6tlsc.c
+++ b/src/sbearssl/sbearssl_s6tlsc.c
@@ -14,10 +14,11 @@
 
 int sbearssl_s6tlsc (char const *const *argv, char const *const *envp, tain_t const *tto, uint32_t preoptions, uint32_t options, uid_t uid, gid_t gid, unsigned int verbosity, char const *servername, int *sfd)
 {
-  int fds[4] = { sfd[0], sfd[1], sfd[0], sfd[1] } ;
+  int fds[5] = { sfd[0], sfd[1], sfd[0], sfd[1] } ;
   stralloc storage = STRALLOC_ZERO ;
   genalloc tas = GENALLOC_ZERO ;
   size_t talen ;
+  pid_t pid ;
 
   if (preoptions & 1)
     strerr_dief1x(100, "client certificates are not supported yet") ;
@@ -44,31 +45,26 @@ int sbearssl_s6tlsc (char const *const *argv, char const *const *envp, tain_t co
       strerr_dief2x(96, "no trust anchor found in ", x) ;
   }
 
+  if (!random_init()) strerr_diefu1sys(111, "initialize random generator") ;
+
+  pid = sbearssl_prep_spawn_drop(argv, envp, fds, uid, gid, !!(preoptions & 2)) ;
+
   {
     unsigned char buf[BR_SSL_BUFSIZE_BIDI] ;
     br_x509_minimal_context xc ;
     br_ssl_client_context cc ;
     br_x509_trust_anchor btas[talen] ;
     size_t i = talen ;
-    pid_t pid ;
+    int wstat ;
 
     stralloc_shrink(&storage) ;
     while (i--)
       sbearssl_ta_to(genalloc_s(sbearssl_ta, &tas) + i, btas + i, storage.s) ;
     genalloc_free(sbearssl_ta, &tas) ;
-    
     br_ssl_client_init_full(&cc, &xc, btas, talen) ;
-
-    if (!random_init())
-      strerr_diefu1sys(111, "initialize random generator") ;
     random_string((char *)buf, 32) ;
     br_ssl_engine_inject_entropy(&cc.eng, buf, 32) ;
     random_finish() ;
-
-    pid = sbearssl_clean_tls_and_spawn(argv, envp, fds, !!(preoptions & 2)) ;
-    if (gid && setgid(gid) < 0) strerr_diefu1sys(111, "setgid") ;
-    if (uid && setuid(uid) < 0) strerr_diefu1sys(111, "setuid") ;
-
     br_ssl_engine_set_buffer(&cc.eng, buf, sizeof(buf), 1) ;
     if (!br_ssl_client_reset(&cc, servername, 0))
       strerr_diefu2x(97, "reset client context: ", sbearssl_error_str(br_ssl_engine_last_error(&cc.eng))) ;
@@ -76,13 +72,8 @@ int sbearssl_s6tlsc (char const *const *argv, char const *const *envp, tain_t co
     if (!sbearssl_x509_minimal_set_tain(&xc, &STAMP))
       strerr_diefu1sys(111, "initialize validation time") ;
 
-    {
-      int wstat ;
-      int r = sbearssl_run(&cc.eng, fds, verbosity, options, tto) ;
-      if (r < 0) strerr_diefu1sys(111, "run SSL engine") ;
-      else if (r) strerr_diefu2x(98, "establish or maintain SSL connection to peer: ", sbearssl_error_str(r)) ;
-      if (wait_pid(pid, &wstat) < 0) strerr_diefu1sys(111, "wait_pid") ;
-      return wait_estatus(wstat) ;
-    }
+    wstat = sbearssl_run(&cc.eng, fds, pid, verbosity, options, tto) ;
+    if (wstat < 0 && wait_pid(pid, &wstat) < 0) strerr_diefu1sys(111, "wait_pid") ;
+    return wait_estatus(wstat) ;
   }
 }
diff --git a/src/sbearssl/sbearssl_s6tlsd.c b/src/sbearssl/sbearssl_s6tlsd.c
index dd7f52a..6c3d163 100644
--- a/src/sbearssl/sbearssl_s6tlsd.c
+++ b/src/sbearssl/sbearssl_s6tlsd.c
@@ -14,10 +14,12 @@
 
 int sbearssl_s6tlsd (char const *const *argv, char const *const *envp, tain_t const *tto, uint32_t preoptions, uint32_t options, uid_t uid, gid_t gid, unsigned int verbosity)
 {
+  int fds[5] = { 0, 1, 0, 1 } ;
   stralloc storage = STRALLOC_ZERO ;
   sbearssl_skey skey ;
   genalloc certs = GENALLOC_ZERO ;
   size_t chainlen ;
+  pid_t pid ;
 
   if (preoptions & 1)
     strerr_dief1x(100, "client certificates are not supported yet") ;
@@ -44,14 +46,17 @@ int sbearssl_s6tlsd (char const *const *argv, char const *const *envp, tain_t co
       strerr_diefu2x(96, "find a certificate in ", x) ;
   }
 
+  if (!random_init()) strerr_diefu1sys(111, "initialize random generator") ;
+
+  pid = sbearssl_prep_spawn_drop(argv, envp, fds, uid, gid, !!(preoptions & 2)) ;
+
   {
-    int fds[4] = { 0, 1, 0, 1 } ;
     unsigned char buf[BR_SSL_BUFSIZE_BIDI] ;
     br_ssl_server_context sc ;
     union br_skey_u key ;
     br_x509_certificate chain[chainlen] ;
     size_t i = chainlen ;
-    pid_t pid ;
+    int wstat ;
 
     stralloc_shrink(&storage) ;
     while (i--)
@@ -83,17 +88,6 @@ int sbearssl_s6tlsd (char const *const *argv, char const *const *envp, tain_t co
       strerr_dief1x(96, "unsupported private key type") ;
     }
 
-    if (!random_init())
-      strerr_diefu1sys(111, "initialize random generator") ;
-    random_string((char *)buf, 32) ;
-    br_ssl_engine_inject_entropy(&sc.eng, buf, 32) ;
-    random_finish() ;
-
-    pid = sbearssl_clean_tls_and_spawn(argv, envp, fds, !!(preoptions & 2)) ;
-    if (!pid) strerr_diefu2sys(111, "spawn ", argv[0]) ;
-    if (gid && setgid(gid) < 0) strerr_diefu1sys(111, "setgid") ;
-    if (uid && setuid(uid) < 0) strerr_diefu1sys(111, "setuid") ;
-
     {
       uint32_t flags = BR_OPT_ENFORCE_SERVER_PREFERENCES | BR_OPT_NO_RENEGOTIATION ;
       if (preoptions & 1)
@@ -104,17 +98,15 @@ int sbearssl_s6tlsd (char const *const *argv, char const *const *envp, tain_t co
       br_ssl_engine_add_flags(&sc.eng, flags) ;
     }
 
+    random_string((char *)buf, 32) ;
+    br_ssl_engine_inject_entropy(&sc.eng, buf, 32) ;
+    random_finish() ;
     br_ssl_engine_set_buffer(&sc.eng, buf, sizeof(buf), 1) ;
     br_ssl_server_reset(&sc) ;
     tain_now_g() ;
 
-    {
-      int wstat ;
-      int r = sbearssl_run(&sc.eng, fds, verbosity, options, tto) ;
-      if (r < 0) strerr_diefu1sys(111, "run SSL engine") ;
-      else if (r) strerr_diefu2x(98, "establish or maintain SSL connection to peer: ", sbearssl_error_str(r)) ;
-      if (wait_pid(pid, &wstat) < 0) strerr_diefu1sys(111, "wait_pid") ;
-      return wait_estatus(wstat) ;
-    }
+    wstat = sbearssl_run(&sc.eng, fds, pid, verbosity, options, tto) ;
+    if (wstat < 0 && wait_pid(pid, &wstat) < 0) strerr_diefu1sys(111, "wait_pid") ;
+    return wait_estatus(wstat) ;
   }
 }