glibc/glibc-upstream-2.33-32.patch

commit 267e174f198532d950a6f419681689d73b2c633c
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date:   Fri Apr 9 20:55:45 2021 +0530

    support: Add capability to fork an sgid child
    
    Add a new function support_capture_subprogram_self_sgid that spawns an
    sgid child of the running program with its own image and returns the
    exit code of the child process.  This functionality is used by at
    least three tests in the testsuite at the moment, so it makes sense to
    consolidate.
    
    There is also a new function support_subprogram_wait which should
    provide simple system() like functionality that does not set up file
    actions.  This is useful in cases where only the return code of the
    spawned subprocess is interesting.
    
    This patch also ports tst-secure-getenv to this new function.  A
    subsequent patch will port other tests.  This also brings an important
    change to tst-secure-getenv behaviour.  Now instead of succeeding, the
    test fails as UNSUPPORTED if it is unable to spawn a setgid child,
    which is how it should have been in the first place.
    Reviewed-by: Carlos O'Donell <carlos@redhat.com>
    
    (cherry picked from commit 716a3bdc41b2b4b864dc64475015ba51e35e1273)

diff --git a/stdlib/tst-secure-getenv.c b/stdlib/tst-secure-getenv.c
index c9ec03866ff8ac3b..5567c9ae215fd924 100644
--- a/stdlib/tst-secure-getenv.c
+++ b/stdlib/tst-secure-getenv.c
@@ -30,167 +30,12 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
+#include <support/check.h>
 #include <support/support.h>
+#include <support/capture_subprocess.h>
 #include <support/test-driver.h>
 
 static char MAGIC_ARGUMENT[] = "run-actual-test";
-#define MAGIC_STATUS 19
-
-/* Return a GID which is not our current GID, but is present in the
-   supplementary group list.  */
-static gid_t
-choose_gid (void)
-{
-  int count = getgroups (0, NULL);
-  if (count < 0)
-    {
-      printf ("getgroups: %m\n");
-      exit (1);
-    }
-  gid_t *groups;
-  groups = xcalloc (count, sizeof (*groups));
-  int ret = getgroups (count, groups);
-  if (ret < 0)
-    {
-      printf ("getgroups: %m\n");
-      exit (1);
-    }
-  gid_t current = getgid ();
-  gid_t not_current = 0;
-  for (int i = 0; i < ret; ++i)
-    {
-      if (groups[i] != current)
-        {
-          not_current = groups[i];
-          break;
-        }
-    }
-  free (groups);
-  return not_current;
-}
-
-
-/* Copies the executable into a restricted directory, so that we can
-   safely make it SGID with the TARGET group ID.  Then runs the
-   executable.  */
-static int
-run_executable_sgid (gid_t target)
-{
-  char *dirname = xasprintf ("%s/secure-getenv.%jd",
-			     test_dir, (intmax_t) getpid ());
-  char *execname = xasprintf ("%s/bin", dirname);
-  int infd = -1;
-  int outfd = -1;
-  int ret = -1;
-  if (mkdir (dirname, 0700) < 0)
-    {
-      printf ("mkdir: %m\n");
-      goto err;
-    }
-  infd = open ("/proc/self/exe", O_RDONLY);
-  if (infd < 0)
-    {
-      printf ("open (/proc/self/exe): %m\n");
-      goto err;
-    }
-  outfd = open (execname, O_WRONLY | O_CREAT | O_EXCL, 0700);
-  if (outfd < 0)
-    {
-      printf ("open (%s): %m\n", execname);
-      goto err;
-    }
-  char buf[4096];
-  for (;;)
-    {
-      ssize_t rdcount = read (infd, buf, sizeof (buf));
-      if (rdcount < 0)
-	{
-	  printf ("read: %m\n");
-	  goto err;
-	}
-      if (rdcount == 0)
-	break;
-      char *p = buf;
-      char *end = buf + rdcount;
-      while (p != end)
-	{
-	  ssize_t wrcount = write (outfd, buf, end - p);
-	  if (wrcount == 0)
-	    errno = ENOSPC;
-	  if (wrcount <= 0)
-	    {
-	      printf ("write: %m\n");
-	      goto err;
-	    }
-	  p += wrcount;
-	}
-    }
-  if (fchown (outfd, getuid (), target) < 0)
-    {
-      printf ("fchown (%s): %m\n", execname);
-      goto err;
-    }
-  if (fchmod (outfd, 02750) < 0)
-    {
-      printf ("fchmod (%s): %m\n", execname);
-      goto err;
-    }
-  if (close (outfd) < 0)
-    {
-      printf ("close (outfd): %m\n");
-      goto err;
-    }
-  if (close (infd) < 0)
-    {
-      printf ("close (infd): %m\n");
-      goto err;
-    }
-
-  int kid = fork ();
-  if (kid < 0)
-    {
-      printf ("fork: %m\n");
-      goto err;
-    }
-  if (kid == 0)
-    {
-      /* Child process.  */
-      char *args[] = { execname, MAGIC_ARGUMENT, NULL };
-      execve (execname, args, environ);
-      printf ("execve (%s): %m\n", execname);
-      _exit (1);
-    }
-  int status;
-  if (waitpid (kid, &status, 0) < 0)
-    {
-      printf ("waitpid: %m\n");
-      goto err;
-    }
-  if (!WIFEXITED (status) || WEXITSTATUS (status) != MAGIC_STATUS)
-    {
-      printf ("Unexpected exit status %d from child process\n",
-	      status);
-      goto err;
-    }
-  ret = 0;
-
-err:
-  if (outfd >= 0)
-    close (outfd);
-  if (infd >= 0)
-    close (infd);
-  if (execname)
-    {
-      unlink (execname);
-      free (execname);
-    }
-  if (dirname)
-    {
-      rmdir (dirname);
-      free (dirname);
-    }
-  return ret;
-}
 
 static int
 do_test (void)
@@ -212,15 +57,15 @@ do_test (void)
       exit (1);
     }
 
-  gid_t target = choose_gid ();
-  if (target == 0)
-    {
-      fprintf (stderr,
-	       "Could not find a suitable GID for user %jd, skipping test\n",
-	       (intmax_t) getuid ());
-      exit (0);
-    }
-  return run_executable_sgid (target);
+  int status = support_capture_subprogram_self_sgid (MAGIC_ARGUMENT);
+
+  if (WEXITSTATUS (status) == EXIT_UNSUPPORTED)
+    return EXIT_UNSUPPORTED;
+
+  if (!WIFEXITED (status))
+    FAIL_EXIT1 ("Unexpected exit status %d from child process\n", status);
+
+  return 0;
 }
 
 static void
@@ -229,23 +74,15 @@ alternative_main (int argc, char **argv)
   if (argc == 2 && strcmp (argv[1], MAGIC_ARGUMENT) == 0)
     {
       if (getgid () == getegid ())
-	{
-	  /* This can happen if the file system is mounted nosuid.  */
-	  fprintf (stderr, "SGID failed: GID and EGID match (%jd)\n",
-		  (intmax_t) getgid ());
-	  exit (MAGIC_STATUS);
-	}
+	/* This can happen if the file system is mounted nosuid.  */
+	FAIL_UNSUPPORTED ("SGID failed: GID and EGID match (%jd)\n",
+		   (intmax_t) getgid ());
       if (getenv ("PATH") == NULL)
-	{
-	  printf ("PATH variable not present\n");
-	  exit (3);
-	}
+	FAIL_EXIT (3, "PATH variable not present\n");
       if (secure_getenv ("PATH") != NULL)
-	{
-	  printf ("PATH variable not filtered out\n");
-	  exit (4);
-	}
-      exit (MAGIC_STATUS);
+	FAIL_EXIT (4, "PATH variable not filtered out\n");
+
+      exit (EXIT_SUCCESS);
     }
 }
 
diff --git a/support/capture_subprocess.h b/support/capture_subprocess.h
index 8969d4a99a093657..4be430f099bcc8cd 100644
--- a/support/capture_subprocess.h
+++ b/support/capture_subprocess.h
@@ -41,6 +41,12 @@ struct support_capture_subprocess support_capture_subprocess
 struct support_capture_subprocess support_capture_subprogram
   (const char *file, char *const argv[]);
 
+/* Copy the running program into a setgid binary and run it with CHILD_ID
+   argument.  If execution is successful, return the exit status of the child
+   program, otherwise return a non-zero failure exit code.  */
+int support_capture_subprogram_self_sgid
+  (char *child_id);
+
 /* Deallocate the subprocess data captured by
    support_capture_subprocess.  */
 void support_capture_subprocess_free (struct support_capture_subprocess *);
diff --git a/support/subprocess.h b/support/subprocess.h
index 11cfc6a07f5ad94a..40d82c7e4db27090 100644
--- a/support/subprocess.h
+++ b/support/subprocess.h
@@ -38,6 +38,11 @@ struct support_subprocess support_subprocess
 struct support_subprocess support_subprogram
   (const char *file, char *const argv[]);
 
+/* Invoke program FILE with ARGV arguments by using posix_spawn and wait for it
+   to complete.  Return program exit status.  */
+int support_subprogram_wait
+  (const char *file, char *const argv[]);
+
 /* Wait for the subprocess indicated by PROC::PID.  Return the status
    indicate by waitpid call.  */
 int support_process_wait (struct support_subprocess *proc);
diff --git a/support/support_capture_subprocess.c b/support/support_capture_subprocess.c
index 3eb825b9afc0b5e6..27bfd19c9374a183 100644
--- a/support/support_capture_subprocess.c
+++ b/support/support_capture_subprocess.c
@@ -20,11 +20,14 @@
 #include <support/capture_subprocess.h>
 
 #include <errno.h>
+#include <fcntl.h>
 #include <stdlib.h>
 #include <support/check.h>
 #include <support/xunistd.h>
 #include <support/xsocket.h>
 #include <support/xspawn.h>
+#include <support/support.h>
+#include <support/test-driver.h>
 
 static void
 transfer (const char *what, struct pollfd *pfd, struct xmemstream *stream)
@@ -102,6 +105,129 @@ support_capture_subprogram (const char *file, char *const argv[])
   return result;
 }
 
+/* Copies the executable into a restricted directory, so that we can
+   safely make it SGID with the TARGET group ID.  Then runs the
+   executable.  */
+static int
+copy_and_spawn_sgid (char *child_id, gid_t gid)
+{
+  char *dirname = xasprintf ("%s/tst-tunables-setuid.%jd",
+			     test_dir, (intmax_t) getpid ());
+  char *execname = xasprintf ("%s/bin", dirname);
+  int infd = -1;
+  int outfd = -1;
+  int ret = 1, status = 1;
+
+  TEST_VERIFY (mkdir (dirname, 0700) == 0);
+  if (support_record_failure_is_failed ())
+    goto err;
+
+  infd = open ("/proc/self/exe", O_RDONLY);
+  if (infd < 0)
+    FAIL_UNSUPPORTED ("unsupported: Cannot read binary from procfs\n");
+
+  outfd = open (execname, O_WRONLY | O_CREAT | O_EXCL, 0700);
+  TEST_VERIFY (outfd >= 0);
+  if (support_record_failure_is_failed ())
+    goto err;
+
+  char buf[4096];
+  for (;;)
+    {
+      ssize_t rdcount = read (infd, buf, sizeof (buf));
+      TEST_VERIFY (rdcount >= 0);
+      if (support_record_failure_is_failed ())
+	goto err;
+      if (rdcount == 0)
+	break;
+      char *p = buf;
+      char *end = buf + rdcount;
+      while (p != end)
+	{
+	  ssize_t wrcount = write (outfd, buf, end - p);
+	  if (wrcount == 0)
+	    errno = ENOSPC;
+	  TEST_VERIFY (wrcount > 0);
+	  if (support_record_failure_is_failed ())
+	    goto err;
+	  p += wrcount;
+	}
+    }
+  TEST_VERIFY (fchown (outfd, getuid (), gid) == 0);
+  if (support_record_failure_is_failed ())
+    goto err;
+  TEST_VERIFY (fchmod (outfd, 02750) == 0);
+  if (support_record_failure_is_failed ())
+    goto err;
+  TEST_VERIFY (close (outfd) == 0);
+  if (support_record_failure_is_failed ())
+    goto err;
+  TEST_VERIFY (close (infd) == 0);
+  if (support_record_failure_is_failed ())
+    goto err;
+
+  /* We have the binary, now spawn the subprocess.  Avoid using
+     support_subprogram because we only want the program exit status, not the
+     contents.  */
+  ret = 0;
+
+  char * const args[] = {execname, child_id, NULL};
+
+  status = support_subprogram_wait (args[0], args);
+
+err:
+  if (outfd >= 0)
+    close (outfd);
+  if (infd >= 0)
+    close (infd);
+  if (execname != NULL)
+    {
+      unlink (execname);
+      free (execname);
+    }
+  if (dirname != NULL)
+    {
+      rmdir (dirname);
+      free (dirname);
+    }
+
+  if (ret != 0)
+    FAIL_EXIT1("Failed to make sgid executable for test\n");
+
+  return status;
+}
+
+int
+support_capture_subprogram_self_sgid (char *child_id)
+{
+  gid_t target = 0;
+  const int count = 64;
+  gid_t groups[count];
+
+  /* Get a GID which is not our current GID, but is present in the
+     supplementary group list.  */
+  int ret = getgroups (count, groups);
+  if (ret < 0)
+    FAIL_UNSUPPORTED("Could not get group list for user %jd\n",
+		     (intmax_t) getuid ());
+
+  gid_t current = getgid ();
+  for (int i = 0; i < ret; ++i)
+    {
+      if (groups[i] != current)
+	{
+	  target = groups[i];
+	  break;
+	}
+    }
+
+  if (target == 0)
+    FAIL_UNSUPPORTED("Could not find a suitable GID for user %jd\n",
+		     (intmax_t) getuid ());
+
+  return copy_and_spawn_sgid (child_id, target);
+}
+
 void
 support_capture_subprocess_free (struct support_capture_subprocess *p)
 {
diff --git a/support/support_subprocess.c b/support/support_subprocess.c
index 2acfc57b7e70732d..89e767ae47e454f1 100644
--- a/support/support_subprocess.c
+++ b/support/support_subprocess.c
@@ -92,6 +92,19 @@ support_subprogram (const char *file, char *const argv[])
   return result;
 }
 
+int
+support_subprogram_wait (const char *file, char *const argv[])
+{
+  posix_spawn_file_actions_t fa;
+
+  posix_spawn_file_actions_init (&fa);
+  struct support_subprocess res = support_subprocess_init ();
+
+  res.pid = xposix_spawn (file, &fa, NULL, argv, environ);
+
+  return support_process_wait (&res);
+}
+
 int
 support_process_wait (struct support_subprocess *proc)
 {