Revert "Merge tag 'keys-acl-20190703' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs"

This reverts merge 0f75ef6a9cff49ff612f7ce0578bced9d0b38325 (and thus
effectively commits

   7a1ade847596 ("keys: Provide KEYCTL_GRANT_PERMISSION")
   2e12256b9a76 ("keys: Replace uid/gid/perm permissions checking with an ACL")

that the merge brought in).

It turns out that it breaks booting with an encrypted volume, and Eric
biggers reports that it also breaks the fscrypt tests [1] and loading of
in-kernel X.509 certificates [2].

The root cause of all the breakage is likely the same, but David Howells
is off email so rather than try to work it out it's getting reverted in
order to not impact the rest of the merge window.

 [1] https://lore.kernel.org/lkml/20190710011559.GA7973@sol.localdomain/
 [2] https://lore.kernel.org/lkml/20190710013225.GB7973@sol.localdomain/

Link: https://lore.kernel.org/lkml/CAHk-=wjxoeMJfeBahnWH=9zShKp2bsVy527vo3_y8HfOdhwAAw@mail.gmail.com/
Reported-by: Eric Biggers <ebiggers@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 24 deletions

diff --git a/fs/nfs/nfs4idmap.c b/fs/nfs/nfs4idmap.c
index 69679f4f2e6c..1e7296395d71 100644
--- a/fs/nfs/nfs4idmap.c
+++ b/fs/nfs/nfs4idmap.c
@@ -72,25 +72,6 @@ struct idmap {
 	const struct cred	*cred;
 };
 
-static struct key_acl nfs_idmap_key_acl = {
-	.usage	= REFCOUNT_INIT(1),
-	.nr_ace	= 2,
-	.possessor_viewable = true,
-	.aces = {
-		KEY_POSSESSOR_ACE(KEY_ACE_VIEW | KEY_ACE_SEARCH | KEY_ACE_READ),
-		KEY_OWNER_ACE(KEY_ACE_VIEW),
-	}
-};
-
-static struct key_acl nfs_idmap_keyring_acl = {
-	.usage	= REFCOUNT_INIT(1),
-	.nr_ace	= 2,
-	.aces = {
-		KEY_POSSESSOR_ACE(KEY_ACE_SEARCH | KEY_ACE_WRITE),
-		KEY_OWNER_ACE(KEY_ACE_VIEW | KEY_ACE_READ),
-	}
-};
-
 static struct user_namespace *idmap_userns(const struct idmap *idmap)
 {
 	if (idmap && idmap->cred)
@@ -227,7 +208,8 @@ int nfs_idmap_init(void)
 
 	keyring = keyring_alloc(".id_resolver",
 				GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, cred,
-				&nfs_idmap_keyring_acl,
+				(KEY_POS_ALL & ~KEY_POS_SETATTR) |
+				KEY_USR_VIEW | KEY_USR_READ,
 				KEY_ALLOC_NOT_IN_QUOTA, NULL, NULL);
 	if (IS_ERR(keyring)) {
 		ret = PTR_ERR(keyring);
@@ -305,13 +287,11 @@ static struct key *nfs_idmap_request_key(const char *name, size_t namelen,
 		return ERR_PTR(ret);
 
 	if (!idmap->cred || idmap->cred->user_ns == &init_user_ns)
-		rkey = request_key(&key_type_id_resolver, desc, "",
-				   &nfs_idmap_key_acl);
+		rkey = request_key(&key_type_id_resolver, desc, "");
 	if (IS_ERR(rkey)) {
 		mutex_lock(&idmap->idmap_mutex);
 		rkey = request_key_with_auxdata(&key_type_id_resolver_legacy,
-						desc, NULL, "", 0, idmap,
-						&nfs_idmap_key_acl);
+						desc, NULL, "", 0, idmap);
 		mutex_unlock(&idmap->idmap_mutex);
 	}
 	if (!IS_ERR(rkey))
@@ -340,6 +320,8 @@ static ssize_t nfs_idmap_get_key(const char *name, size_t namelen,
 	}
 
 	rcu_read_lock();
+	rkey->perm |= KEY_USR_VIEW;
+
 	ret = key_validate(rkey);
 	if (ret < 0)
 		goto out_up;