Merge pull request #74 from OttoHollmann/master

Synchronize haveged instances during switch root
jirka-h · Nov 28, 2022 · 1c5eb6b · 1c5eb6b
2 parents 20e69a2 + 55dd6b7
commit 1c5eb6b
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Showing 4 changed files with 48 additions and 5 deletions.
diff --git a/configure.ac b/configure.ac
@@ -10,7 +10,7 @@ AC_CONFIG_HEADER([config.h])
 AM_INIT_AUTOMAKE([subdir-objects no-dependencies])
 AC_CONFIG_SRCDIR([src/haveged.c])
 AC_CHECK_TYPES([uint32_t, uint8_t])
-HA_LDFLAGS=""
+HA_LDFLAGS="-pthread"
 
 ##libtool_start##
 LT_INIT
@@ -73,7 +73,6 @@ AC_ARG_ENABLE(threads,
    , enable_threads="no")
 if test "x$enable_threads" = "xyes"; then
    AC_DEFINE(NUMBER_CORES, 4, [Define maxium number of collection threads])
-   HA_LDFLAGS="-pthread"
 else
    AC_DEFINE(NUMBER_CORES, 1, [Define to single collection thread])
 fi

diff --git a/src/havegecmd.c b/src/havegecmd.c
@@ -39,6 +39,7 @@
 #include <sys/stat.h>
 #include <sys/un.h>
 #include <unistd.h>
+#include <semaphore.h>
 
 #ifndef HAVE_STRUCT_UCRED
 struct ucred
@@ -54,6 +55,7 @@ struct ucred
 int first_byte;
 int socket_fd;
 static char errmsg[1024];
+extern  sem_t *sem;
 
 static int new_root(               /* RETURN: status                        */
    const char *root,               /* IN: path of the new root file system  */
@@ -95,6 +97,7 @@ static int new_root(               /* RETURN: status                        */
                strerror(errno));
       goto err;
       }
+   sem_close(sem);
    ret = execv((const char *)path, argv);
    if (ret < 0) {
       snprintf(&errmsg[0], sizeof(errmsg)-1,
@@ -265,8 +268,14 @@ int socket_handler(                /* RETURN: closed file descriptor        */
       }
 
    if (magic[1] == '\002') {       /* ASCII start of text: read argument provided */
-      uint32_t alen;
-
+      uint32_t alen = 0;
+
+      /*
+       * wait for the haveged -c instance to finish writting
+       * before continuing to read from the socket
+       */
+      sem_wait(sem);
+      sem_post(sem);
       ret = receive_uinteger(fd, &alen);
       if (ret < 0) {
          print_msg("%s: can not read from UNIX socket\n", params->daemon);
@@ -285,6 +294,11 @@ int socket_handler(                /* RETURN: closed file descriptor        */
          print_msg("%s: can not read from UNIX socket\n", params->daemon);
          goto out;
          }
+      /*
+       * We no more need the semaphore unlink it
+       * Not sure if it is the best place to unlink here
+       */
+      sem_unlink(SEM_NAME);
       }
 
    clen = sizeof(struct ucred);
@@ -444,7 +458,7 @@ int receive_uinteger(              /* RETURN: status                        */
    int fd,                         /* IN: file descriptor                   */
    uint32_t *value)                /* OUT: 32 bit unsigned integer          */
 {
-   uint8_t buffer[4];
+   uint8_t buffer[4] = {0};
 
    if (safein(fd, buffer, 4 * sizeof(uint8_t)) < 0)
       return -1;

diff --git a/src/havegecmd.h b/src/havegecmd.h
@@ -49,6 +49,8 @@ extern "C" {
 #define SOCK_NONBLOCK 0
 #endif
 
+#define SEM_NAME "haveged_sem"
+
 /**
  * Open and listen on a UNIX socket to get command from there
  */

diff --git a/src/haveged.c b/src/haveged.c
@@ -34,6 +34,7 @@
 #include <sys/stat.h>
 #include <unistd.h>
 #include <time.h>
+#include <semaphore.h>
 
 #ifndef NO_DAEMON
 #include <syslog.h>
@@ -131,6 +132,8 @@ static void usage(int db, int nopts, struct option *long_options, const char **c
 
 static sigset_t mask, omask;
 
+sem_t *sem = NULL;
+
 #define  ATOU(a)     (unsigned int)atoi(a)
 /**
  * Entry point
@@ -360,6 +363,15 @@ int main(int argc, char **argv)
       fd_set read_fd;
       sigset_t block;
 
+      /* init semaphore */
+      sem = sem_open(SEM_NAME, 0);
+      if (sem == NULL) {
+         print_msg("sem_open() failed \n");
+         print_msg("Error : %s \n", strerror(errno));
+         ret = -1;
+         goto err;
+         }
+
       socket_fd = cmd_connect(params);
       if (socket_fd < 0) {
          ret = -1;
@@ -377,9 +389,19 @@ int main(int argc, char **argv)
             root = optarg;
             size = (uint32_t)strlen(root)+1;
             cmd[1] = '\002';
+            /*
+             * Synchronise haveged -c instance and daemon instance
+             * prevent daemon instance from readin messages
+             * from the socket until the -c instance finish writting
+             */
+            sem_wait(sem);
             safeout(socket_fd, &cmd[0], 2);
             send_uinteger(socket_fd, size);
             safeout(socket_fd, root, size);
+            /*
+             * unblock the daemon instance as we finished writting
+             */
+            sem_post(sem);
             break;
          case MAGIC_CLOSE:
             ptr = &cmd[0];
@@ -440,6 +462,7 @@ int main(int argc, char **argv)
          }
    err:
       close(socket_fd);
+      sem_close(sem);
       return ret;
       }
    else if (!(params->setup & RUN_AS_APP)){
@@ -455,6 +478,11 @@ int main(int argc, char **argv)
             fprintf(stderr, "%s: disabling command mode for this instance\n", params->daemon);
          }
       }
+      /* Initilize named semaphore to synchronize command isntances */
+      sem = sem_open(SEM_NAME, O_CREAT, 0644, 1);
+      if (sem == NULL) {
+         error_exit("Couldn't create nammed semaphore " SEM_NAME" error: %s", strerror(errno));
+      }
     }
 #endif
    if (params->tests_config == 0)
-Original file line number
+Diff line change
@@ Expand Up / @@ -49,6 +49,8 @@ extern "C" { @@
     #define SOCK_NONBLOCK 0
     #endif
+    #define SEM_NAME "haveged_sem"
     /**
      * Open and listen on a UNIX socket to get command from there
      */
@@ Expand Down @@