Merge tag 'execve-v6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull execve updates from Kees Cook:

 - Support non-BSS ELF segments with zero filesz

   Eric Biederman and I refactored ELF segment loading to handle the
   case where a segment has a smaller filesz than memsz. Traditionally
   linkers only did this for .bss and it was always the last segment. As
   a result, the kernel only handled this case when it was the last
   segment. We've had two recent cases where linkers were trying to use
   these kinds of segments for other reasons, and the were in the middle
   of the segment list. There was no good reason for the kernel not to
   support this, and the refactor actually ends up making things more
   readable too.

 - Enable namespaced binfmt_misc

   Christian Brauner has made it possible to use binfmt_misc with mount
   namespaces. This means some traditionally root-only interfaces (for
   adding/removing formats) are now more exposed (but believed to be
   safe).

 - Remove struct tag 'dynamic' from ELF UAPI

   Alejandro Colomar noticed that the ELF UAPI has been polluting the
   struct namespace with an unused and overly generic tag named
   "dynamic" for no discernible reason for many many years. After
   double-checking various distro source repositories, it has been
   removed.

 - Clean up binfmt_elf_fdpic debug output (Greg Ungerer)

* tag 'execve-v6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  binfmt_misc: enable sandboxed mounts
  binfmt_misc: cleanup on filesystem umount
  binfmt_elf_fdpic: clean up debug warnings
  mm: Remove unused vm_brk()
  binfmt_elf: Only report padzero() errors when PROT_WRITE
  binfmt_elf: Use elf_load() for library
  binfmt_elf: Use elf_load() for interpreter
  binfmt_elf: elf_bss no longer used by load_elf_binary()
  binfmt_elf: Support segments with 0 filesz and misaligned starts
  elf, uapi: Remove struct tag 'dynamic'

2 files changed, 16 insertions, 0 deletions

diff --git a/kernel/user.c b/kernel/user.c
index d667debeafd6..03cedc366dc9 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -18,8 +18,18 @@
 #include <linux/interrupt.h>
 #include <linux/export.h>
 #include <linux/user_namespace.h>
+#include <linux/binfmts.h>
 #include <linux/proc_ns.h>
 
+#if IS_ENABLED(CONFIG_BINFMT_MISC)
+struct binfmt_misc init_binfmt_misc = {
+	.entries = LIST_HEAD_INIT(init_binfmt_misc.entries),
+	.enabled = true,
+	.entries_lock = __RW_LOCK_UNLOCKED(init_binfmt_misc.entries_lock),
+};
+EXPORT_SYMBOL_GPL(init_binfmt_misc);
+#endif
+
 /*
  * userns count is 1 for root user, 1 for init_uts_ns,
  * and 1 for... ?
@@ -67,6 +77,9 @@ struct user_namespace init_user_ns = {
 	.keyring_name_list = LIST_HEAD_INIT(init_user_ns.keyring_name_list),
 	.keyring_sem = __RWSEM_INITIALIZER(init_user_ns.keyring_sem),
 #endif
+#if IS_ENABLED(CONFIG_BINFMT_MISC)
+	.binfmt_misc = &init_binfmt_misc,
+#endif
 };
 EXPORT_SYMBOL_GPL(init_user_ns);
 
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 1d8e47bed3f1..d52a894ecf57 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -213,6 +213,9 @@ static void free_user_ns(struct work_struct *work)
 			kfree(ns->projid_map.forward);
 			kfree(ns->projid_map.reverse);
 		}
+#if IS_ENABLED(CONFIG_BINFMT_MISC)
+		kfree(ns->binfmt_misc);
+#endif
 		retire_userns_sysctls(ns);
 		key_free_user_ns(ns);
 		ns_free_inum(&ns->ns);