linux: Add open_tree

It was added on Linux 5.2 (a07b20004793d8926f78d63eb5980559f7813404)
to return a O_PATH-opened file descriptor to an existing mountpoint.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

NEWS

@@ -41,11 +41,11 @@ Major new features:
   have adverse impact.  It is incompatible with EDNS0 usage and DNSSEC
   validation by applications.
 
-* On Linux, the fsopen, fsmount, move_mount, fsconfig, and fspick functions
+* On Linux, the fsopen, fsmount, move_mount, fsconfig, fspick, and open_tree
-  have been added.  They are part of the new Linux kernel mount APIs that
+  functions have been added.  They are part of the new Linux kernel mount
-  allow applications to more flexibly configure and operate on filesystem
+  APIs that allow applications to more flexibly configure and operate on
-  mounts.  The new mount APIs are specifically designed to work with
+  filesystem mounts.  The new mount APIs are specifically designed to work
-  namespaces.
+  with namespaces.
 
 * localedef now accepts locale definition files encoded in UTF-8.
   Previously, input bytes not within the ASCII range resulted in

sysdeps/unix/sysv/linux/Versions

@@ -305,6 +305,7 @@ libc {
     fsopen;
     fspick;
     move_mount;
+    open_tree;
     pidfd_open;
     pidfd_getfd;
     pidfd_send_signal;

sysdeps/unix/sysv/linux/aarch64/libc.abilist

@@ -2621,6 +2621,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/alpha/libc.abilist

@@ -2718,6 +2718,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/arc/libc.abilist

@@ -2382,6 +2382,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/arm/be/libc.abilist

@@ -501,6 +501,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/arm/le/libc.abilist

@@ -498,6 +498,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/csky/libc.abilist

@@ -2657,6 +2657,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/hppa/libc.abilist

@@ -2606,6 +2606,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/i386/libc.abilist

@@ -2790,6 +2790,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/ia64/libc.abilist

@@ -2556,6 +2556,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist

@@ -502,6 +502,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist

@@ -2733,6 +2733,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/microblaze/be/libc.abilist

@@ -2706,6 +2706,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/microblaze/le/libc.abilist

@@ -2703,6 +2703,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist

@@ -2698,6 +2698,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist

@@ -2696,6 +2696,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist

@@ -2704,6 +2704,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist

@@ -2607,6 +2607,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/nios2/libc.abilist

@@ -2745,6 +2745,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/or1k/libc.abilist

@@ -2128,6 +2128,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist

@@ -2760,6 +2760,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist

@@ -2793,6 +2793,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/powerpc/powerpc64/be/libc.abilist

@@ -2515,6 +2515,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/powerpc/powerpc64/le/libc.abilist

@@ -2817,6 +2817,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/riscv/rv32/libc.abilist

@@ -2384,6 +2384,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist

@@ -2584,6 +2584,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist

@@ -2758,6 +2758,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist

@@ -2552,6 +2552,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/sh/be/libc.abilist

@@ -2613,6 +2613,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/sh/le/libc.abilist

@@ -2610,6 +2610,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist

@@ -2753,6 +2753,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist

@@ -2579,6 +2579,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/sys/mount.h

@@ -21,6 +21,7 @@
 #ifndef _SYS_MOUNT_H
 #define _SYS_MOUNT_H	1
 
+#include <fcntl.h>
 #include <features.h>
 #include <sys/ioctl.h>
 
@@ -192,6 +193,10 @@ enum fsconfig_command
 #define FSCONFIG_CMD_RECONFIGURE FSCONFIG_CMD_RECONFIGURE
 };
 
+/* open_tree flags.  */
+#define OPEN_TREE_CLONE    1         /* Clone the target tree and attach the clone */
+#define OPEN_TREE_CLOEXEC  O_CLOEXEC /* Close the file on execve() */
+
 
 __BEGIN_DECLS
 
@@ -231,6 +236,10 @@ extern int fsconfig (int __fd, unsigned int __cmd, const char *__key,
 extern int fspick (int __dfd, const char *__path, unsigned int __flags)
   __THROW;
 
+/* Open the mount point FILENAME in directory DFD using FLAGS.  */
+extern int open_tree (int __dfd, const char *__filename, unsigned int __flags)
+  __THROW;
+
 __END_DECLS
 
 #endif /* _SYS_MOUNT_H */

sysdeps/unix/sysv/linux/syscalls.list

@@ -43,6 +43,7 @@ move_mount	EXTRA	move_mount	i:isisU	move_mount
 munlock		-	munlock		i:aU	munlock
 munlockall	-	munlockall	i:	munlockall
 nfsservctl	EXTRA	nfsservctl	i:ipp	__compat_nfsservctl	nfsservctl@GLIBC_2.0:GLIBC_2.28
+open_tree	EXTRA	open_tree	i:isU	open_tree
 pipe2		-	pipe2		i:fi	__pipe2		pipe2
 pidfd_open	EXTRA	pidfd_open	i:iU	pidfd_open
 pidfd_getfd	EXTRA	pidfd_getfd	i:iiU	pidfd_getfd

sysdeps/unix/sysv/linux/tst-mount-consts.py

@@ -55,7 +55,8 @@ def main():
         check('FSOPEN_.*'),
         check('FSMOUNT_.*'),
         # MOVE_MOUNT__MASK may vary depending of the kernel version.
-        check('MOVE_MOUNT_.*', 'MOVE_MOUNT__MASK'))
+        check('MOVE_MOUNT_.*', 'MOVE_MOUNT__MASK'),
+        check('OPEN_TREE_*'))
     sys.exit(status)
 
 if __name__ == '__main__':

sysdeps/unix/sysv/linux/x86_64/64/libc.abilist

@@ -2530,6 +2530,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F

sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist

@@ -2636,6 +2636,7 @@ GLIBC_2.36 fsmount F
 GLIBC_2.36 fsopen F
 GLIBC_2.36 fspick F
 GLIBC_2.36 move_mount F
+GLIBC_2.36 open_tree F
 GLIBC_2.36 pidfd_getfd F
 GLIBC_2.36 pidfd_open F
 GLIBC_2.36 pidfd_send_signal F