sslGenerateCertificate: Don't use the shell

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

diff --git a/libhttp/ssl.c b/libhttp/ssl.c
index c8de457ddf07b659a1d7a987744ee57f7b82a65f..ceb2eb862c1dede79e44fa91072f3433d22d22aa 100755 (executable)
--- a/libhttp/ssl.c
+++ b/libhttp/ssl.c
@@ -58,6 +58,7 @@
 #include <string.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/wait.h>
 #include <unistd.h>
 
 #include "libhttp/ssl.h"
@@ -347,18 +348,32 @@ static void sslGenerateCertificate(const char *certificate,
                                    const char *serverName) {
  debug("Auto-generating missing certificate \"%s\" for \"%s\"",
        certificate, serverName);
-  char *cmd         = stringPrintf(NULL,
-    "set -e; "
-    "exec 2>/dev/null </dev/null; "
-    "umask 0377; "
-    "PATH=/usr/bin:/usr/sbin "
-    "openssl req -x509 -nodes -days 7300 -newkey rsa:1024 -keyout /dev/stdout "
-                                 "-out /dev/stdout -subj '/CN=%s/' | cat>'%s'",
-    serverName, certificate);
-  if (system(cmd)) {
+
+  pid_t pid = fork();
+  if (pid == -1) {
     warn("Failed to generate self-signed certificate \"%s\"", certificate);
+  } else if (pid == 0) {
+    int fd = NOINTR(open("/dev/null", O_RDONLY));
+    check(fd != -1);
+    check(NOINTR(dup2(fd, STDERR_FILENO)) == STDERR_FILENO);
+    check(NOINTR(close(fd)) == 0);
+    fd = NOINTR(open("/dev/null", O_WRONLY));
+    check(fd != -1);
+    check(NOINTR(dup2(fd, STDIN_FILENO)) == STDIN_FILENO);
+    check(NOINTR(close(fd)) == 0);
+    umask(077);
+    check(setenv("PATH", "/usr/bin:/usr/sbin", 1) == 0);
+    execlp("openssl", "openssl", "req", "-x509", "-nodes", "-days", "7300",
+           "-newkey", "rsa:1024", "-keyout", certificate, "-out", certificate,
+           "-subj", stringPrintf(NULL, "/CN=%s/", serverName),
+           (char *)NULL);
+    check(0);
+  } else {
+    int status;
+    check(NOINTR(waitpid(pid, &status, 0)) == pid);
+    if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
+      warn("Failed to generate self-signed certificate \"%s\"", certificate);
   }
-  free(cmd);
 }
 
 static const unsigned char *sslSecureReadASCIIFileToMem(int fd) {