Fix: agent port file is o+w when launching as root

[lttng-tools.git] / src / bin / lttng-sessiond / shm.c

diff --git a/src/bin/lttng-sessiond/shm.c b/src/bin/lttng-sessiond/shm.c
index 929752aa24dd98ff06ee714adbf4f629e570f771..8422230708253fd3a246fc8ec1eb5fdaeada5fe7 100644 (file)
--- a/src/bin/lttng-sessiond/shm.c
+++ b/src/bin/lttng-sessiond/shm.c
@@ -21,8 +21,7 @@
 #include "shm.h"
 
 /*
- * Using fork to set umask in the child process (not multi-thread safe). We
- * deal with the shm_open vs ftruncate race (happening when the sessiond owns
+ * We deal with the shm_open vs ftruncate race (happening when the sessiond owns
  * the shm and does not let everybody modify it, to ensure safety against
  * shm_unlink) by simply letting the mmap fail and retrying after a few
  * seconds. For global shm, everybody has rw access to it until the sessiond
@@ -31,7 +30,7 @@
 static int get_wait_shm(char *shm_path, size_t mmap_size, int global)
 {
        int wait_shm_fd, ret;
-       mode_t mode;
+       mode_t mode, old_mode;
 
        assert(shm_path);
 
@@ -51,11 +50,7 @@ static int get_wait_shm(char *shm_path, size_t mmap_size, int global)
                mode |= S_IROTH | S_IWOTH;
        }
 
-       /*
-        * We're alone in a child process, so we can modify the process-wide
-        * umask.
-        */
-       umask(~mode);
+       old_mode = umask(~mode);
 
        /*
         * Try creating shm (or get rw access). We don't do an exclusive open,
@@ -103,7 +98,7 @@ static int get_wait_shm(char *shm_path, size_t mmap_size, int global)
        ret = ftruncate(wait_shm_fd, mmap_size);
        if (ret < 0) {
                PERROR("ftruncate wait shm");
-               exit(EXIT_FAILURE);
+               goto error;
        }
 
 #ifndef __FreeBSD__
@@ -111,7 +106,7 @@ static int get_wait_shm(char *shm_path, size_t mmap_size, int global)
                ret = fchown(wait_shm_fd, 0, 0);
                if (ret < 0) {
                        PERROR("fchown");
-                       exit(EXIT_FAILURE);
+                       goto error;
                }
                /*
                 * If global session daemon, any application can
@@ -122,13 +117,13 @@ static int get_wait_shm(char *shm_path, size_t mmap_size, int global)
                ret = fchmod(wait_shm_fd, mode);
                if (ret < 0) {
                        PERROR("fchmod");
-                       exit(EXIT_FAILURE);
+                       goto error;
                }
        } else {
                ret = fchown(wait_shm_fd, getuid(), getgid());
                if (ret < 0) {
                        PERROR("fchown");
-                       exit(EXIT_FAILURE);
+                       goto error;
                }
        }
 #else
@@ -136,13 +131,20 @@ static int get_wait_shm(char *shm_path, size_t mmap_size, int global)
 #endif
 
        DBG("Got the wait shm fd %d", wait_shm_fd);
-
+end:
+       (void) umask(old_mode);
        return wait_shm_fd;
 
 error:
        DBG("Failing to get the wait shm fd");
+       if (wait_shm_fd >= 0) {
+               if (close(wait_shm_fd)) {
+                       PERROR("Failed to close wait shm file descriptor during error handling");
+               }
+       }
 
-       return -1;
+       wait_shm_fd = -1;
+       goto end;
 }
 
 /*