diff mbox series

Linux: Add execveat system call wrapper

Message ID 20210421181159.3579223-1-ahajkova@redhat.com
State Committed
Delegated to: Adhemerval Zanella Netto
Headers show
Series Linux: Add execveat system call wrapper | expand

Commit Message

Alexandra Hájková April 21, 2021, 6:11 p.m. UTC
From: Alexandra Hájková <ahajkova@redhat.com>

 Also add the test for the new wrapper.
---
This version drops the fallback support.

 NEWS                                          |   5 +
 posix/Makefile                                |   5 +-
 posix/Versions                                |   3 +
 posix/execveat.c                              |  41 ++++
 posix/tst-execveat.c                          | 183 ++++++++++++++++++
 posix/unistd.h                                |   5 +
 sysdeps/mach/hurd/i386/libc.abilist           |   1 +
 sysdeps/unix/sysv/linux/aarch64/libc.abilist  |   1 +
 sysdeps/unix/sysv/linux/alpha/libc.abilist    |   1 +
 sysdeps/unix/sysv/linux/arc/libc.abilist      |   1 +
 sysdeps/unix/sysv/linux/arm/be/libc.abilist   |   1 +
 sysdeps/unix/sysv/linux/arm/le/libc.abilist   |   1 +
 sysdeps/unix/sysv/linux/csky/libc.abilist     |   1 +
 sysdeps/unix/sysv/linux/execveat.c            |  51 +++++
 sysdeps/unix/sysv/linux/hppa/libc.abilist     |   1 +
 sysdeps/unix/sysv/linux/i386/libc.abilist     |   1 +
 sysdeps/unix/sysv/linux/ia64/libc.abilist     |   1 +
 .../sysv/linux/m68k/coldfire/libc.abilist     |   1 +
 .../unix/sysv/linux/m68k/m680x0/libc.abilist  |   1 +
 .../sysv/linux/microblaze/be/libc.abilist     |   1 +
 .../sysv/linux/microblaze/le/libc.abilist     |   1 +
 .../sysv/linux/mips/mips32/fpu/libc.abilist   |   1 +
 .../sysv/linux/mips/mips32/nofpu/libc.abilist |   1 +
 .../sysv/linux/mips/mips64/n32/libc.abilist   |   1 +
 .../sysv/linux/mips/mips64/n64/libc.abilist   |   1 +
 sysdeps/unix/sysv/linux/nios2/libc.abilist    |   1 +
 .../linux/powerpc/powerpc32/fpu/libc.abilist  |   1 +
 .../powerpc/powerpc32/nofpu/libc.abilist      |   1 +
 .../linux/powerpc/powerpc64/be/libc.abilist   |   1 +
 .../linux/powerpc/powerpc64/le/libc.abilist   |   1 +
 .../unix/sysv/linux/riscv/rv32/libc.abilist   |   1 +
 .../unix/sysv/linux/riscv/rv64/libc.abilist   |   1 +
 .../unix/sysv/linux/s390/s390-32/libc.abilist |   1 +
 .../unix/sysv/linux/s390/s390-64/libc.abilist |   1 +
 sysdeps/unix/sysv/linux/sh/be/libc.abilist    |   1 +
 sysdeps/unix/sysv/linux/sh/le/libc.abilist    |   1 +
 .../sysv/linux/sparc/sparc32/libc.abilist     |   1 +
 .../sysv/linux/sparc/sparc64/libc.abilist     |   1 +
 .../unix/sysv/linux/x86_64/64/libc.abilist    |   1 +
 .../unix/sysv/linux/x86_64/x32/libc.abilist   |   1 +
 40 files changed, 324 insertions(+), 2 deletions(-)
 create mode 100644 posix/execveat.c
 create mode 100644 posix/tst-execveat.c
 create mode 100644 sysdeps/unix/sysv/linux/execveat.c

Comments

Adhemerval Zanella May 3, 2021, 7:20 p.m. UTC | #1
On 21/04/2021 15:11, Alexandra Hájková via Libc-alpha wrote:
> From: Alexandra Hájková <ahajkova@redhat.com>
> 
>  Also add the test for the new wrapper.

Patch looks ok in general, but there are minor issues. Since it is being
back and forth for some time, I took the liberty to fix them and I will
push it upstream.

> 
> diff --git a/NEWS b/NEWS
> index aa0f10a891..0765db4543 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -18,6 +18,11 @@ Major new features:
>    a dump of information related to IFUNC resolver operation and
>    glibc-hwcaps subdirectory selection.
>  
> +* The function execveat has been added and it operates similar to execve.
> +  The syscall is already used to implement fexecve without requiring /proc to
> +  be mounted.  Similar to fexecve, if the syscall is not supported ENOSYS is
> +  returned.
> +

With the fallback removal, execveat does not act similar to fexecve.  I changed
the NEWS entry to:

  * On Linux, the function execveat has been added.  It operates similar to
    execve and it is is already used to implement fexecve without requiring
    /proc to be mounted.  However, different than fexecve, if the syscall is not
    supported by the kernel an error is returned instead of trying a fallback.


> +int
> +call_execveat (int fd, const char *pathname, int flags, int expected_fail,
> +               int num)
> +{
> +  char *envp[] = { (char *) "FOO=3", NULL };
> +  char *argv[] = { (char *) "sh", (char *) "-c", (char *) "exit $FOO", NULL };
> +  pid_t pid;
> +  int status;
> +
> +  if (test_verbose > 0)
> +    printf ("call line number: %d\n", num);
> +
> +  pid = xfork ();
> +  if (pid == 0)
> +    {
> +      TEST_COMPARE (execveat (fd, pathname, argv, envp, flags), -1);
> +      if (errno == ENOSYS)
> +        FAIL_UNSUPPORTED ("execveat is unimplemented");

This will print 'execveat is unimplemented', since the WEXITSTATUS below
will already handle it.  Instead I replace it with:

  exit (EXIT_UNSUPPORTED); 


> +int
> +execveat (int dirfd, const char *path, char *const argv[], char *const envp[],
> +          int flags)
> +{
> +  /* Avoid implicit array coercion in syscall macros.  */
> +  INLINE_SYSCALL_CALL (execveat, dirfd, path, &argv[0], &envp[0], flags);
> +#ifndef __ASSUME_EXECVEAT
> +  if ((flags & ~(AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW)) != 0)
> +    return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
> +
> +  if (errno != ENOSYS)
> +    return -1;
> +  else
> +    return ENOSYS;
> +#endif
> +
> +  return -1;
> +}

Since there is no fallback anymore, there is no need to check for flag
support neither handle the errno value.  It can be simple as:

  int
  execveat (int dirfd, const char *path, char *const argv[], char *const envp[],
            int flags)
  {
    /* Avoid implicit array coercion in syscall macros.  */
    return INLINE_SYSCALL_CALL (execveat, dirfd, path, &argv[0], &envp[0],
                                flags);
  }
diff mbox series

Patch

diff --git a/NEWS b/NEWS
index aa0f10a891..0765db4543 100644
--- a/NEWS
+++ b/NEWS
@@ -18,6 +18,11 @@  Major new features:
   a dump of information related to IFUNC resolver operation and
   glibc-hwcaps subdirectory selection.
 
+* The function execveat has been added and it operates similar to execve.
+  The syscall is already used to implement fexecve without requiring /proc to
+  be mounted.  Similar to fexecve, if the syscall is not supported ENOSYS is
+  returned.
+
 Deprecated and removed features, and other changes affecting compatibility:
 
   [Add deprecations, removals and changes affecting compatibility here]
diff --git a/posix/Makefile b/posix/Makefile
index 64494557f1..fa0dc0ea20 100644
--- a/posix/Makefile
+++ b/posix/Makefile
@@ -66,7 +66,8 @@  routines :=								      \
 	posix_madvise							      \
 	get_child_max sched_cpucount sched_cpualloc sched_cpufree \
 	streams-compat \
-	shm-directory
+	shm-directory                                                         \
+	execveat
 
 aux		:= init-posix environ
 tests		:= test-errno tstgetopt testfnm runtests runptests \
@@ -103,7 +104,7 @@  tests		:= test-errno tstgetopt testfnm runtests runptests \
 		   tst-sysconf-empty-chroot tst-glob_symlinks tst-fexecve \
 		   tst-glob-tilde test-ssize-max tst-spawn4 bug-regex37 \
 		   bug-regex38 tst-regcomp-truncated tst-spawn-chdir \
-		   tst-wordexp-nocmd
+		   tst-wordexp-nocmd tst-execveat
 
 # Test for the glob symbol version that was replaced in glibc 2.27.
 ifeq ($(have-GLIBC_2.26)$(build-shared),yesyes)
diff --git a/posix/Versions b/posix/Versions
index cfd3819966..b77e251e00 100644
--- a/posix/Versions
+++ b/posix/Versions
@@ -147,6 +147,9 @@  libc {
   }
   GLIBC_2.30 {
   }
+  GLIBC_2.34 {
+    execveat;
+  }
   GLIBC_PRIVATE {
     __libc_fork; __libc_pread; __libc_pwrite;
     __nanosleep_nocancel; __pause_nocancel;
diff --git a/posix/execveat.c b/posix/execveat.c
new file mode 100644
index 0000000000..7ae95f72f6
--- /dev/null
+++ b/posix/execveat.c
@@ -0,0 +1,41 @@ 
+/* Execute program relative to a directory file descriptor.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <stddef.h>
+#include <unistd.h>
+
+/* Replace the current process, executing PATH relative to difrd with
+   arguments argv and environment envp.
+   argv and envp are terminated by NULL pointers.  */
+int
+__execveat (int dirfd, const char *path, char *const argv[], char *const envp[],
+            int flags)
+{
+  if (path == NULL || argv == NULL || envp == NULL)
+    {
+      __set_errno (EINVAL);
+      return -1;
+    }
+
+  __set_errno (ENOSYS);
+  return -1;
+}
+stub_warning (execveat)
+
+weak_alias (__execveat, execveat)
diff --git a/posix/tst-execveat.c b/posix/tst-execveat.c
new file mode 100644
index 0000000000..186134564f
--- /dev/null
+++ b/posix/tst-execveat.c
@@ -0,0 +1,183 @@ 
+/* Test execveat at the various corner cases.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <fcntl.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <support/check.h>
+#include <support/support.h>
+#include <support/temp_file.h>
+#include <support/xdlfcn.h>
+#include <support/xstdio.h>
+#include <support/xunistd.h>
+#include <wait.h>
+#include <support/test-driver.h>
+
+int
+call_execveat (int fd, const char *pathname, int flags, int expected_fail,
+               int num)
+{
+  char *envp[] = { (char *) "FOO=3", NULL };
+  char *argv[] = { (char *) "sh", (char *) "-c", (char *) "exit $FOO", NULL };
+  pid_t pid;
+  int status;
+
+  if (test_verbose > 0)
+    printf ("call line number: %d\n", num);
+
+  pid = xfork ();
+  if (pid == 0)
+    {
+      TEST_COMPARE (execveat (fd, pathname, argv, envp, flags), -1);
+      if (errno == ENOSYS)
+        FAIL_UNSUPPORTED ("execveat is unimplemented");
+      else if (errno == expected_fail)
+        {
+          if (test_verbose > 0)
+            printf ("expected fail: errno %d\n", errno);
+          _exit (0);
+        }
+      else
+        FAIL_EXIT1 ("execveat failed: %m (%d)", errno);
+    }
+  xwaitpid (pid, &status, 0);
+
+  if (!WIFEXITED (status))
+    FAIL_RET ("child hasn't exited normally");
+
+  if (WIFEXITED (status))
+    {
+      if (WEXITSTATUS (status) == EXIT_UNSUPPORTED)
+        FAIL_UNSUPPORTED ("execveat is unimplemented");
+      else if (expected_fail != 0)
+        TEST_COMPARE (WEXITSTATUS (status), 0);
+      else
+        TEST_COMPARE (WEXITSTATUS (status), 3);
+    }
+  return 0;
+}
+
+static int
+do_test (void)
+{
+  DIR *dirp;
+  int fd, fd_out;
+  char *tmp_dir, *symlink_name, *tmp_sh;
+  struct stat64 st;
+
+  dirp = opendir ("/bin");
+  if (dirp == NULL)
+    FAIL_EXIT1 ("failed to open /bin");
+  fd = dirfd (dirp);
+
+  /* Call execveat for various fd/pathname combinations.  */
+
+  /* Check the pathname relative to a valid dirfd.  */
+  call_execveat (fd, "sh", 0, 0, __LINE__);
+  xchdir ("/bin");
+  /* Use the special value AT_FDCWD as dirfd. Quoting open(2):
+     If pathname is relative and dirfd is the special value AT_FDCWD, then
+     pathname is interpreted relative to the current working directory of
+     the calling process.  */
+  call_execveat (AT_FDCWD, "sh", 0, 0, __LINE__);
+  xclose (fd);
+#ifdef O_PATH
+  /* Check the pathname relative to a valid dirfd with O_PATH.  */
+  fd = xopen ("/bin", O_PATH | O_DIRECTORY, O_RDONLY);
+  call_execveat (fd, "sh", 0, 0, __LINE__);
+  xclose (fd);
+
+  /* Check absolute pathname, dirfd should be ignored.  */
+  call_execveat (AT_FDCWD, "/bin/sh", 0, 0, __LINE__);
+  fd = xopen ("/usr", O_PATH | O_DIRECTORY, 0);
+  /* Same check for absolute pathname, but with input file descriptor
+     openend with different flags.  The dirfd should be ignored.  */
+  call_execveat (fd, "/bin/sh", 0, 0, __LINE__);
+  xclose (fd);
+#endif
+
+  fd = xopen ("/usr", O_RDONLY, 0);
+  /* Same check for absolute pathname, but with input file descriptor
+     openend with different flags.  The dirfd should be ignored.  */
+  call_execveat (fd, "/bin/sh", 0, 0, __LINE__);
+  xclose (fd);
+
+  fd = xopen ("/bin/sh", O_RDONLY, 0);
+  /* Check relative pathname, where dirfd does not point to a directory.  */
+  call_execveat (fd, "sh", 0, ENOTDIR, __LINE__);
+  /* Check absolute pathname, but dirfd is a regular file.  The dirfd
+     should be ignored.  */
+  call_execveat (fd, "/bin/sh", 0, 0, __LINE__);
+  xclose (fd);
+
+#ifdef O_PATH
+  /* Quoting open(2): O_PATH
+     Obtain a file descriptor that can be used for two purposes: to
+     indicate a location in the filesystem tree and to perform
+     operations that act purely at the file descriptor level.  */
+  fd = xopen ("/bin/sh", O_PATH, 0);
+  /* Check the empty pathname.  Dirfd is a regular file with O_PATH.  */
+  call_execveat (fd, "", 0, ENOENT, __LINE__);
+  /* Same check for an empty pathname, but with AT_EMPTY_PATH flag.
+     Quoting open(2):
+     If oldpath is an empty string, create a link to the file referenced
+     by olddirfd (which may have been obtained using the open(2) O_PATH flag. */
+  call_execveat (fd, "", AT_EMPTY_PATH, 0, __LINE__);
+  call_execveat (fd, "", AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW, 0, __LINE__);
+  xclose (fd);
+
+  /* Create a temporary directory "tmp_dir" and create a symbolik link tmp_sh
+     pointing to /bin/sh inside the tmp_dir. Open dirfd as a symbolic link.  */
+  tmp_dir = support_create_temp_directory ("tst-execveat_dir");
+  symlink_name = xasprintf ("%s/symlink", tmp_dir);
+  xsymlink ("tmp_sh", symlink_name);
+  add_temp_file (symlink_name);
+  tmp_sh = xasprintf ("%s/tmp_sh", tmp_dir);
+  add_temp_file (tmp_sh);
+  fd_out = xopen (symlink_name, O_CREAT | O_WRONLY, 0);
+  xstat ("/bin/sh", &st);
+  fd = xopen ("/bin/sh", O_RDONLY, 0);
+  xcopy_file_range (fd, 0, fd_out, 0, st.st_size, 0);
+  xfchmod (fd_out, 0700);
+  xclose (fd);
+  xclose (fd_out);
+  fd_out = xopen (symlink_name, O_PATH, 0);
+
+ /* Check the empty pathname. Dirfd is a symbolic link.  */
+  call_execveat (fd_out, "", 0, ENOENT, __LINE__);
+  call_execveat (fd_out, "", AT_EMPTY_PATH, 0, __LINE__);
+  call_execveat (fd_out, "", AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW, 0,
+                 __LINE__);
+  xclose (fd_out);
+  free (symlink_name);
+  free (tmp_sh);
+  free (tmp_dir);
+#endif
+
+  /* Call execveat with closed fd, we expect this to fail with EBADF.  */
+  call_execveat (fd, "sh", 0, EBADF, __LINE__);
+  /* Call execveat with closed fd, we expect this to pass because the pathname is
+     absolute.  */
+  call_execveat (fd, "/bin/sh", 0, 0, __LINE__);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/posix/unistd.h b/posix/unistd.h
index 3f22763379..d9d8929f71 100644
--- a/posix/unistd.h
+++ b/posix/unistd.h
@@ -295,6 +295,11 @@  extern int euidaccess (const char *__name, int __type)
 /* An alias for `euidaccess', used by some other systems.  */
 extern int eaccess (const char *__name, int __type)
      __THROW __nonnull ((1));
+
+/* Execute program relative to a directory file descriptor.  */
+extern int execveat (int __fd, const char *__path, char *const __argv[],
+                     char *const __envp[], int __flags)
+    __THROW __nonnull ((2, 3));
 #endif
 
 #ifdef __USE_ATFILE
diff --git a/sysdeps/mach/hurd/i386/libc.abilist b/sysdeps/mach/hurd/i386/libc.abilist
index fcba25ee5e..fb2683edc2 100644
--- a/sysdeps/mach/hurd/i386/libc.abilist
+++ b/sysdeps/mach/hurd/i386/libc.abilist
@@ -2207,6 +2207,7 @@  GLIBC_2.33 stat64 F
 GLIBC_2.34 __isnanf128 F
 GLIBC_2.34 __libc_start_main F
 GLIBC_2.34 _hurd_libc_proc_init F
+GLIBC_2.34 execveat F
 GLIBC_2.4 __confstr_chk F
 GLIBC_2.4 __fgets_chk F
 GLIBC_2.4 __fgets_unlocked_chk F
diff --git a/sysdeps/unix/sysv/linux/aarch64/libc.abilist b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
index 851f15a566..132589648e 100644
--- a/sysdeps/unix/sysv/linux/aarch64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
@@ -2174,4 +2174,5 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
diff --git a/sysdeps/unix/sysv/linux/alpha/libc.abilist b/sysdeps/unix/sysv/linux/alpha/libc.abilist
index 33b426ef20..891e20f5e6 100644
--- a/sysdeps/unix/sysv/linux/alpha/libc.abilist
+++ b/sysdeps/unix/sysv/linux/alpha/libc.abilist
@@ -2263,6 +2263,7 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 _IO_fprintf F
 GLIBC_2.4 _IO_printf F
diff --git a/sysdeps/unix/sysv/linux/arc/libc.abilist b/sysdeps/unix/sysv/linux/arc/libc.abilist
index c09947ad58..d86333c354 100644
--- a/sysdeps/unix/sysv/linux/arc/libc.abilist
+++ b/sysdeps/unix/sysv/linux/arc/libc.abilist
@@ -1933,4 +1933,5 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
diff --git a/sysdeps/unix/sysv/linux/arm/be/libc.abilist b/sysdeps/unix/sysv/linux/arm/be/libc.abilist
index 57be971f81..78d7d19f79 100644
--- a/sysdeps/unix/sysv/linux/arm/be/libc.abilist
+++ b/sysdeps/unix/sysv/linux/arm/be/libc.abilist
@@ -156,6 +156,7 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 _Exit F
 GLIBC_2.4 _IO_2_1_stderr_ D 0xa0
diff --git a/sysdeps/unix/sysv/linux/arm/le/libc.abilist b/sysdeps/unix/sysv/linux/arm/le/libc.abilist
index 2db02fae07..4242914991 100644
--- a/sysdeps/unix/sysv/linux/arm/le/libc.abilist
+++ b/sysdeps/unix/sysv/linux/arm/le/libc.abilist
@@ -153,6 +153,7 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 _Exit F
 GLIBC_2.4 _IO_2_1_stderr_ D 0xa0
diff --git a/sysdeps/unix/sysv/linux/csky/libc.abilist b/sysdeps/unix/sysv/linux/csky/libc.abilist
index 0dd3527892..e6d2a4f09b 100644
--- a/sysdeps/unix/sysv/linux/csky/libc.abilist
+++ b/sysdeps/unix/sysv/linux/csky/libc.abilist
@@ -2117,4 +2117,5 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
diff --git a/sysdeps/unix/sysv/linux/execveat.c b/sysdeps/unix/sysv/linux/execveat.c
new file mode 100644
index 0000000000..a11b3ca46d
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/execveat.c
@@ -0,0 +1,51 @@ 
+/* Execute program relative to a directory file descriptor.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+
+#include <sysdep.h>
+#include <sys/syscall.h>
+#include <kernel-features.h>
+#include <fd_to_filename.h>
+#include <not-cancel.h>
+
+/* Execute the file FD refers to, overlaying the running program image.
+   ARGV and ENVP are passed to the new program, as for `execve'.  */
+int
+execveat (int dirfd, const char *path, char *const argv[], char *const envp[],
+          int flags)
+{
+  /* Avoid implicit array coercion in syscall macros.  */
+  INLINE_SYSCALL_CALL (execveat, dirfd, path, &argv[0], &envp[0], flags);
+#ifndef __ASSUME_EXECVEAT
+  if ((flags & ~(AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW)) != 0)
+    return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
+
+  if (errno != ENOSYS)
+    return -1;
+  else
+    return ENOSYS;
+#endif
+
+  return -1;
+}
diff --git a/sysdeps/unix/sysv/linux/hppa/libc.abilist b/sysdeps/unix/sysv/linux/hppa/libc.abilist
index 04c32f9b65..aebcb2cda5 100644
--- a/sysdeps/unix/sysv/linux/hppa/libc.abilist
+++ b/sysdeps/unix/sysv/linux/hppa/libc.abilist
@@ -2076,6 +2076,7 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 __confstr_chk F
 GLIBC_2.4 __fgets_chk F
diff --git a/sysdeps/unix/sysv/linux/i386/libc.abilist b/sysdeps/unix/sysv/linux/i386/libc.abilist
index cfd4e55e57..026dc67c14 100644
--- a/sysdeps/unix/sysv/linux/i386/libc.abilist
+++ b/sysdeps/unix/sysv/linux/i386/libc.abilist
@@ -2253,6 +2253,7 @@  GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __isnanf128 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 __confstr_chk F
 GLIBC_2.4 __fgets_chk F
diff --git a/sysdeps/unix/sysv/linux/ia64/libc.abilist b/sysdeps/unix/sysv/linux/ia64/libc.abilist
index 426e15f4f6..2c2c16e9e1 100644
--- a/sysdeps/unix/sysv/linux/ia64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/ia64/libc.abilist
@@ -2110,6 +2110,7 @@  GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __isnanf128 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 __confstr_chk F
 GLIBC_2.4 __fgets_chk F
diff --git a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
index bdecf60fae..7a00dd7869 100644
--- a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
@@ -157,6 +157,7 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 _Exit F
 GLIBC_2.4 _IO_2_1_stderr_ D 0x98
diff --git a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
index eaa5a97a61..a1fdc560a5 100644
--- a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
@@ -2196,6 +2196,7 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 __confstr_chk F
 GLIBC_2.4 __fgets_chk F
diff --git a/sysdeps/unix/sysv/linux/microblaze/be/libc.abilist b/sysdeps/unix/sysv/linux/microblaze/be/libc.abilist
index 571315511b..c5ab412504 100644
--- a/sysdeps/unix/sysv/linux/microblaze/be/libc.abilist
+++ b/sysdeps/unix/sysv/linux/microblaze/be/libc.abilist
@@ -2168,4 +2168,5 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
diff --git a/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist b/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist
index 9d4c1f53f7..d4e9ff1675 100644
--- a/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist
+++ b/sysdeps/unix/sysv/linux/microblaze/le/libc.abilist
@@ -2165,4 +2165,5 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
index 6de58a4680..4d9dbb3901 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
@@ -2159,6 +2159,7 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 __confstr_chk F
 GLIBC_2.4 __fgets_chk F
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
index e1c971c361..488f2aa6de 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
@@ -2157,6 +2157,7 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 __confstr_chk F
 GLIBC_2.4 __fgets_chk F
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
index 28d6d3284d..bac10468b7 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
@@ -2165,6 +2165,7 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 __confstr_chk F
 GLIBC_2.4 __fgets_chk F
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
index 3060a503ab..95200c2064 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
@@ -2159,6 +2159,7 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 __confstr_chk F
 GLIBC_2.4 __fgets_chk F
diff --git a/sysdeps/unix/sysv/linux/nios2/libc.abilist b/sysdeps/unix/sysv/linux/nios2/libc.abilist
index 24e0a6f16a..b5b3bc7bd4 100644
--- a/sysdeps/unix/sysv/linux/nios2/libc.abilist
+++ b/sysdeps/unix/sysv/linux/nios2/libc.abilist
@@ -2207,4 +2207,5 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
index b9cccc3fe5..38e4e3cb21 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
@@ -2223,6 +2223,7 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 _IO_fprintf F
 GLIBC_2.4 _IO_printf F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
index 5c81a23740..41b4abd7ef 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
@@ -2256,6 +2256,7 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 _IO_fprintf F
 GLIBC_2.4 _IO_printf F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist
index a61d2502d5..7ea617f84f 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist
@@ -2078,6 +2078,7 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 _IO_fprintf F
 GLIBC_2.4 _IO_printf F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libc.abilist
index ec9ae25539..6b3de81190 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libc.abilist
@@ -2370,4 +2370,5 @@  GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __isnanf128 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
diff --git a/sysdeps/unix/sysv/linux/riscv/rv32/libc.abilist b/sysdeps/unix/sysv/linux/riscv/rv32/libc.abilist
index b08ece30b8..ff85889ea1 100644
--- a/sysdeps/unix/sysv/linux/riscv/rv32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/riscv/rv32/libc.abilist
@@ -1935,4 +1935,5 @@  GLIBC_2.33 write F
 GLIBC_2.33 writev F
 GLIBC_2.33 wscanf F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
diff --git a/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist b/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist
index 12ced01cf7..f18bc160c4 100644
--- a/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist
@@ -2135,4 +2135,5 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
index 7ed5e4c515..eb80905f99 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
@@ -2221,6 +2221,7 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 _IO_fprintf F
 GLIBC_2.4 _IO_printf F
diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
index 73a46b01b2..360817ff74 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
@@ -2114,6 +2114,7 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 _IO_fprintf F
 GLIBC_2.4 _IO_printf F
diff --git a/sysdeps/unix/sysv/linux/sh/be/libc.abilist b/sysdeps/unix/sysv/linux/sh/be/libc.abilist
index 2aa68f1def..535b0a329b 100644
--- a/sysdeps/unix/sysv/linux/sh/be/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sh/be/libc.abilist
@@ -2083,6 +2083,7 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 __confstr_chk F
 GLIBC_2.4 __fgets_chk F
diff --git a/sysdeps/unix/sysv/linux/sh/le/libc.abilist b/sysdeps/unix/sysv/linux/sh/le/libc.abilist
index 07f3c23873..82ee8a8203 100644
--- a/sysdeps/unix/sysv/linux/sh/le/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sh/le/libc.abilist
@@ -2080,6 +2080,7 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 __confstr_chk F
 GLIBC_2.4 __fgets_chk F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
index cc1d278c72..af3be1fd59 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
@@ -2212,6 +2212,7 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 _IO_fprintf F
 GLIBC_2.4 _IO_printf F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
index 79ca3d5d9c..8b41b11497 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
@@ -2131,6 +2131,7 @@  GLIBC_2.33 mknodat F
 GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 __confstr_chk F
 GLIBC_2.4 __fgets_chk F
diff --git a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
index da0974f11a..3d1089a3e8 100644
--- a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
@@ -2092,6 +2092,7 @@  GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __isnanf128 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F
 GLIBC_2.4 __confstr_chk F
 GLIBC_2.4 __fgets_chk F
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
index d3d155e7c0..593beb66d9 100644
--- a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
@@ -2189,4 +2189,5 @@  GLIBC_2.33 stat F
 GLIBC_2.33 stat64 F
 GLIBC_2.34 __isnanf128 F
 GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 execveat F
 GLIBC_2.34 pthread_kill F