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

[lttng-tools.git] / src / common / shm.cpp

diff --git a/src/common/shm.cpp b/src/common/shm.cpp
index e3fa9b6404c3ad6f85d99293f664aeac9aebefb9..300ffe357e98cafdfabb02146ab8736bc8474104 100644 (file)
--- a/src/common/shm.cpp
+++ b/src/common/shm.cpp
@@ -21,8 +21,7 @@
 #include "shm.hpp"
 
 /*
- * 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;
 
        LTTNG_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,
@@ -104,7 +99,7 @@ static int get_wait_shm(char *shm_path, size_t mmap_size, int global)
        if (ret < 0) {
                PERROR("Failed to truncate \"wait\" shared memory object: fd = %d, size = %zu",
                                wait_shm_fd, mmap_size);
-               exit(EXIT_FAILURE);
+               goto error;
        }
 
        if (global) {
@@ -112,7 +107,7 @@ static int get_wait_shm(char *shm_path, size_t mmap_size, int global)
                if (ret < 0) {
                        PERROR("Failed to set ownership of \"wait\" shared memory object: fd = %d, owner = 0, group = 0",
                                        wait_shm_fd);
-                       exit(EXIT_FAILURE);
+                       goto error;
                }
                /*
                 * If global session daemon, any application can
@@ -124,14 +119,14 @@ static int get_wait_shm(char *shm_path, size_t mmap_size, int global)
                if (ret < 0) {
                        PERROR("Failed to set the mode of the \"wait\" shared memory object: fd = %d, mode = %d",
                                        wait_shm_fd, mode);
-                       exit(EXIT_FAILURE);
+                       goto error;
                }
        } else {
                ret = fchown(wait_shm_fd, getuid(), getgid());
                if (ret < 0) {
                        PERROR("Failed to set ownership of \"wait\" shared memory object: fd = %d, owner = %d, group = %d",
                                        wait_shm_fd, getuid(), getgid());
-                       exit(EXIT_FAILURE);
+                       goto error;
                }
        }
 
@@ -139,13 +134,20 @@ static int get_wait_shm(char *shm_path, size_t mmap_size, int global)
                        shm_path, mmap_size, global ? "true" : "false",
                        wait_shm_fd);
 
+end:
+       (void) umask(old_mode);
        return wait_shm_fd;
 
 error:
-       DBG("Failed to open shared memory file descriptor: path = '%s', mmap_size = %zu, global = %s",
-                       shm_path, mmap_size, global ? "true" : "false");
+       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;
 }
 
 /*