Merge tag 'v6.6-fs.proc.uapi' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull procfs fixes from Christian Brauner:
 "Mode changes to files under /proc/<pid>/ aren't supported ever since
  commit 6d76fa58 ("Don't allow chmod() on the /proc/<pid>/ files").

  Due to an oversight in commit 1b3044e3 ("procfs: fix pthread
  cross-thread naming if !PR_DUMPABLE") in switching from REG to NOD,
  mode changes on /proc/thread-self/comm were accidently allowed.

  Similar, mode changes for all files beneath /proc/<pid>/net/ are
  blocked but mode changes on /proc/<pid>/net itself were accidently
  allowed.

  Both issues come down to not using the generic proc_setattr() helper
  which blocks all mode changes. This is rectified with this pull
  request.

  This also removes a strange nolibc test that abused /proc/<pid>/net
  for testing mode changes. Using procfs for this test never made a lot
  of sense given procfs has special semantics for almost everything
  anway.

  Both changes are minor user-visible changes. It is however very
  unlikely that mode changes on proc/<pid>/net and
  /proc/thread-self/comm are something that userspace relies on"

* tag 'v6.6-fs.proc.uapi' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  procfs: block chmod on /proc/thread-self/comm
  proc: use generic setattr() for /proc/$PID/net
  selftests/nolibc: drop test chmod_net

fs/proc/base.c

@@ -3583,7 +3583,8 @@ static int proc_tid_comm_permission(struct mnt_idmap *idmap,
 }
 
 static const struct inode_operations proc_tid_comm_inode_operations = {
-		.permission = proc_tid_comm_permission,
+		.setattr	= proc_setattr,
+		.permission	= proc_tid_comm_permission,
 };
 
 /*

fs/proc/proc_net.c

@@ -321,6 +321,7 @@ static int proc_tgid_net_getattr(struct mnt_idmap *idmap,
 const struct inode_operations proc_net_inode_operations = {
 	.lookup		= proc_tgid_net_lookup,
 	.getattr	= proc_tgid_net_getattr,
+	.setattr        = proc_setattr,
 };
 
 static int proc_tgid_net_readdir(struct file *file, struct dir_context *ctx)

tools/testing/selftests/nolibc/nolibc-test.c

@@ -577,7 +577,6 @@ int run_syscall(int min, int max)
 		CASE_TEST(chdir_root);        EXPECT_SYSZR(1, chdir("/")); break;
 		CASE_TEST(chdir_dot);         EXPECT_SYSZR(1, chdir(".")); break;
 		CASE_TEST(chdir_blah);        EXPECT_SYSER(1, chdir("/blah"), -1, ENOENT); break;
-		CASE_TEST(chmod_net);         EXPECT_SYSZR(proc, chmod("/proc/self/net", 0555)); break;
 		CASE_TEST(chmod_self);        EXPECT_SYSER(proc, chmod("/proc/self", 0555), -1, EPERM); break;
 		CASE_TEST(chown_self);        EXPECT_SYSER(proc, chown("/proc/self", 0, 0), -1, EPERM); break;
 		CASE_TEST(chroot_root);       EXPECT_SYSZR(euid0, chroot("/")); break;