make socket path non-configurable, set strict mount options for tmpfs

3 files changed, 13 insertions, 55 deletions

diff --git a/config.h b/config.h
index 60f7fd4..27645ea 100644
--- a/config.h
+++ b/config.h
@@ -5,9 +5,7 @@
 #define USER_LISTS_MAX 50
 #define CONTAINER_DIR_VAR "VOIDNSRUN_DIR"
 #define UNDO_BIN_VAR "VOIDNSUNDO_BIN"
-#define SOCK_DIR_VAR "VOIDNSRUN_SOCK_DIR"
-#define SOCK_DIR_DEFAULT "/run/voidnsrun"
-#define SOCK_NAME "/sock"
+#define SOCK_PATH "/run/voidnsrun/sock"
 #define VOIDNSUNDO_NAME "voidnsundo"
 
 #endif //VOIDNSRUN_CONFIG_H
diff --git a/voidnsrun.c b/voidnsrun.c
index ba48139..d82d00e 100644
--- a/voidnsrun.c
+++ b/voidnsrun.c
@@ -10,6 +10,7 @@
 #include <stdbool.h>
 #include <dirent.h>
 #include <signal.h>
+#include <libgen.h>
 #include <sys/mount.h>
 #include <sys/stat.h>
 #include <sys/types.h>
@@ -38,9 +39,6 @@ void usage(const char *progname)
             "               " UNDO_BIN_VAR " environment variable is used.\n"
             "    -i:        Don't treat missing source or target for an added mount\n"
             "               as an error.\n"
-            "    -s:        Socket directory path. When this option is not present,\n"
-            "               " SOCK_DIR_VAR " environment variable is used. If both are\n"
-            "               missing, defaults to " SOCK_DIR_DEFAULT ".\n"
             "    -V:        Verbose output.\n"
             "    -h:        Print this help.\n"
             "    -v:        Print version.\n",
@@ -114,8 +112,8 @@ int main(int argc, char **argv)
 
     int nsfd = -1;
     char *dir = NULL;
+    char buf[PATH_MAX];
     char *undo_bin = NULL;
-    char *sock_dir = NULL;
     int sock_fd = -1, sock_conn = -1;
     size_t dirlen;
     int c;
@@ -135,7 +133,7 @@ int main(int argc, char **argv)
     struct intarray tounlink;
     intarray_alloc(&tounlink, USER_LISTS_MAX);
 
-    while ((c = getopt(argc, argv, "vhm:r:u:U:is:V")) != -1) {
+    while ((c = getopt(argc, argv, "vhm:r:u:U:iV")) != -1) {
         switch (c) {
         case 'v':
             printf("%s\n", PROG_VERSION);
@@ -152,9 +150,6 @@ int main(int argc, char **argv)
         case 'U':
             undo_bin = optarg;
             break;
-        case 's':
-            sock_dir = optarg;
-            break;
         case 'V':
             g_verbose = true;
             break;
@@ -217,19 +212,16 @@ int main(int argc, char **argv)
                    strerror(errno));
 
     /* Check socket directory. */
-    if (!sock_dir)
-        sock_dir = getenv(SOCK_DIR_VAR);
-    if (!sock_dir)
-        sock_dir = SOCK_DIR_DEFAULT;
-    if (strlen(sock_dir) > SOCK_DIR_PATH_MAX)
-        ERROR_EXIT("error: socket directory path is too long.\n");
-
+    strncpy(buf, SOCK_PATH, PATH_MAX);
+    char *sock_dir = dirname(buf);
     if (access(sock_dir, F_OK) == -1) {
         if (mkdir(sock_dir, 0700) == -1)
             ERROR_EXIT("error: failed to create %s directory.\n", sock_dir);
     } else {
         if ((dirptr = opendir(sock_dir)) == NULL)
             ERROR_EXIT("error: %s is not a directory.\n", sock_dir);
+        if (exists(SOCK_PATH) && unlink(SOCK_PATH) == -1)
+            ERROR_EXIT("failed to unlink %s: %s", SOCK_PATH, strerror(errno));
     }
     DEBUG("sock_dir=%s\n", sock_dir);
 
@@ -263,7 +255,7 @@ int main(int argc, char **argv)
         ERROR_EXIT("error: some undo mounts failed.\n");
 
     /* Mount sock_dir as tmpfs. It will only be visible in this namespace. */
-    if (mount("tmpfs", sock_dir, "tmpfs", 0, NULL) == -1)
+    if (mount("tmpfs", sock_dir, "tmpfs", 0, "size=4k,mode=0700,uid=0,gid=0") == -1)
         ERROR_EXIT("mount: error mounting tmpfs in %s.\n", sock_dir);
 
     /* Fork. */
@@ -297,8 +289,7 @@ int main(int argc, char **argv)
 
         struct sockaddr_un sock_addr = {0};
         sock_addr.sun_family = AF_UNIX;
-        strcpy(sock_addr.sun_path, sock_dir);
-        strcat(sock_addr.sun_path, SOCK_NAME);
+        strncpy(sock_addr.sun_path, SOCK_PATH, 108);
 
         if (bind(sock_fd, (struct sockaddr *)&sock_addr, sizeof(sock_addr)) == -1)
             ERROR_EXIT("bind: %s\n", strerror(errno));
@@ -312,7 +303,7 @@ int main(int argc, char **argv)
             send_fd(sock_conn, nsfd);
         }
     } else {
-        /* Parent process. Dropping root rights. */
+        /* Parent process. Drop root rights. */
         uid_t uid = getuid();
         gid_t gid = getgid();
 
@@ -326,7 +317,7 @@ int main(int argc, char **argv)
         if (chdir(cwd) == -1)
             DEBUG("chdir: %s\n", strerror(errno));
 
-        /* Launching program. */
+        /* Launch program. */
         if (execvp(argv[optind], (char *const *)argv+optind) == -1)
             ERROR_EXIT("execvp(%s): %s\n", argv[optind], strerror(errno));
     }
diff --git a/voidnsundo.c b/voidnsundo.c
index fac27aa..89dfefc 100644
--- a/voidnsundo.c
+++ b/voidnsundo.c
@@ -6,7 +6,6 @@
 #include <libgen.h>
 #include <stdbool.h>
 #include <getopt.h>
-#include <dirent.h>
 #include <errno.h>
 #include <unistd.h>
 #include <sched.h>
@@ -25,9 +24,6 @@ void usage(const char *progname)
     printf("Usage: %s [OPTIONS] PROGRAM [ARGS]\n", progname);
     printf("\n"
            "Options:\n"
-           "    -s:        Socket directory path. When this option is not present,\n"
-           "               " SOCK_DIR_VAR " environment variable is used. If both are\n"
-           "               missing, defaults to " SOCK_DIR_DEFAULT ".\n"
            "    -V:        Verbose output.\n"
            "    -h:        Print this help.\n"
            "    -v:        Print version.\n");
@@ -37,7 +33,6 @@ int main(int argc, char **argv)
 {
     bool binded = strcmp(basename(argv[0]), VOIDNSUNDO_NAME) != 0;
     int c;
-    char *sock_dir = NULL;
     int sock_fd = -1;
     int exit_code = 1;
     char realpath_buf[PATH_MAX];
@@ -56,9 +51,6 @@ int main(int argc, char **argv)
             case 'h':
                 usage(argv[0]);
                 return 0;
-            case 's':
-                sock_dir = optarg;
-                break;
             case 'V':
                 g_verbose = true;
                 break;
@@ -77,25 +69,6 @@ int main(int argc, char **argv)
         /* DEBUG("/proc/self/exe points to %s\n", realpath_buf); */
     }
 
-    /* Check socket directory. */
-    DIR *dirptr = NULL;
-    if (!sock_dir)
-        sock_dir = getenv(SOCK_DIR_VAR);
-    if (!sock_dir)
-        sock_dir = SOCK_DIR_DEFAULT;
-    if (strlen(sock_dir) > SOCK_DIR_PATH_MAX)
-        ERROR_EXIT("error: socket directory path is too long.\n");
-    if (!isdir(sock_dir))
-        ERROR_EXIT("error: %s is not a directory.\n", sock_dir);
-    if (access(sock_dir, F_OK) == -1) {
-        ERROR_EXIT("error: failed to access socket directory: %s.\n",
-                   strerror(errno));
-    } else {
-        if ((dirptr = opendir(sock_dir)) == NULL)
-            ERROR_EXIT("error: %s is not a directory.\n", sock_dir);
-    }
-    DEBUG("sock_dir=%s\n", sock_dir);
-
     /* Get current working directory. */
     getcwd(cwd, PATH_MAX);
     DEBUG("cwd=%s\n", cwd);
@@ -107,8 +80,7 @@ int main(int argc, char **argv)
 
     struct sockaddr_un sock_addr = {0};
     sock_addr.sun_family  = AF_UNIX;
-    strcpy(sock_addr.sun_path, sock_dir);
-    strcat(sock_addr.sun_path, SOCK_NAME);
+    strncpy(sock_addr.sun_path, SOCK_PATH, 108);
 
     if (connect(sock_fd, (struct sockaddr *)&sock_addr, sizeof(sock_addr)) == -1)
         ERROR_EXIT("connect: %s\n", strerror(errno));
@@ -144,9 +116,6 @@ int main(int argc, char **argv)
     exit_code = 0;
 
 end:
-    if (dirptr != NULL)
-        closedir(dirptr);
-
     if (sock_fd != -1)
         close(sock_fd);