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>

2 files changed, 31 insertions, 106 deletions

diff --git a/Documentation/security/keys/core.rst b/Documentation/security/keys/core.rst
index bc561ca95c86..d6d8b0b756b6 100644
--- a/Documentation/security/keys/core.rst
+++ b/Documentation/security/keys/core.rst
@@ -57,9 +57,9 @@ Each key has a number of attributes:
      type provides an operation to perform a match between the description on a
      key and a criterion string.
 
-  *  Each key has an owner user ID, a group ID and an ACL.  These are used to
-     control what a process may do to a key from userspace, and whether a
-     kernel service will be able to find the key.
+  *  Each key has an owner user ID, a group ID and a permissions mask. These
+     are used to control what a process may do to a key from userspace, and
+     whether a kernel service will be able to find the key.
 
   *  Each key can be set to expire at a specific time by the key type's
      instantiation function. Keys can also be immortal.
@@ -198,110 +198,43 @@ The key service provides a number of features besides keys:
 Key Access Permissions
 ======================
 
-Keys have an owner user ID, a group ID and an ACL.  The ACL is made up of a
-sequence of ACEs that each contain three elements:
+Keys have an owner user ID, a group access ID, and a permissions mask. The mask
+has up to eight bits each for possessor, user, group and other access. Only
+six of each set of eight bits are defined. These permissions granted are:
 
-  * The type of subject.
-  * The subject.
+  *  View
 
-    These two together indicate the subject to whom the permits are granted.
-    The type can be one of:
+     This permits a key or keyring's attributes to be viewed - including key
+     type and description.
 
-     * ``KEY_ACE_SUBJ_STANDARD``
+  *  Read
 
-       The subject is a standard 'macro' type.  The subject can be one of:
-
-        * ``KEY_ACE_EVERYONE``
-
-          The permits are granted to everyone.  It replaces the old 'other'
-          type on the assumption that you wouldn't grant a permission to other
-          that you you wouldn't grant to everyone else.
-
-        * ``KEY_ACE_OWNER``
-
-          The permits are granted to the owner of the key (key->uid).
-
-        * ``KEY_ACE_GROUP``
-
-          The permits are granted to the key's group (key->gid).
-
-        * ``KEY_ACE_POSSESSOR``
-
-          The permits are granted to anyone who possesses the key.
-
-  * The set of permits granted to the subject.  These include:
-
-     * ``KEY_ACE_VIEW``
-
-       This permits a key or keyring's attributes to be viewed - including the
-       key type and description.
-
-     * ``KEY_ACE_READ``
-
-       This permits a key's payload to be viewed or a keyring's list of linked
-       keys.
-
-     * ``KEY_ACE_WRITE``
-
-       This permits a key's payload to be instantiated or updated, or it allows
-       a link to be added to or removed from a keyring.
-
-     * ``KEY_ACE_SEARCH``
-
-       This permits keyrings to be searched and keys to be found. Searches can
-       only recurse into nested keyrings that have search permission set.
-
-     * ``KEY_ACE_LINK``
-
-       This permits a key or keyring to be linked to. To create a link from a
-       keyring to a key, a process must have Write permission on the keyring
-       and Link permission on the key.
-
-     * ``KEY_ACE_SET_SECURITY``
-
-       This permits a key's UID, GID and permissions mask to be changed.
+     This permits a key's payload to be viewed or a keyring's list of linked
+     keys.
 
-     * ``KEY_ACE_INVAL``
+  *  Write
 
-       This permits a key to be invalidated with KEYCTL_INVALIDATE.
+     This permits a key's payload to be instantiated or updated, or it allows a
+     link to be added to or removed from a keyring.
 
-     * ``KEY_ACE_REVOKE``
+  *  Search
 
-       This permits a key to be revoked with KEYCTL_REVOKE.
+     This permits keyrings to be searched and keys to be found. Searches can
+     only recurse into nested keyrings that have search permission set.
 
-     * ``KEY_ACE_JOIN``
+  *  Link
 
-       This permits a keyring to be joined as a session by
-       KEYCTL_JOIN_SESSION_KEYRING or KEYCTL_SESSION_TO_PARENT.
+     This permits a key or keyring to be linked to. To create a link from a
+     keyring to a key, a process must have Write permission on the keyring and
+     Link permission on the key.
 
-     * ``KEY_ACE_CLEAR``
+  *  Set Attribute
 
-       This permits a keyring to be cleared.
+     This permits a key's UID, GID and permissions mask to be changed.
 
 For changing the ownership, group ID or permissions mask, being the owner of
 the key or having the sysadmin capability is sufficient.
 
-The legacy KEYCTL_SETPERM and KEYCTL_DESCRIBE functions can only see/generate
-View, Read, Write, Search, Link and SetAttr permits, and do this for each of
-possessor, user, group and other permission sets as a 32-bit flag mask.  These
-will be approximated/inferred:
-
-        SETPERM Permit  Implied ACE Permit
-        =============== =======================
-        Search          Inval, Join
-        Write           Revoke, Clear
-        Setattr         Set Security, Revoke
-
-        ACE Permit      Described as
-        =============== =======================
-        Inval           Search
-        Join            Search
-        Revoke          Write (unless Setattr)
-        Clear           write
-        Set Security    Setattr
-
-'Other' will be approximated as/inferred from the 'Everyone' subject.
-
 
 SELinux Support
 ===============
@@ -1151,8 +1084,7 @@ payload contents" for more information.
 
         struct key *request_key(const struct key_type *type,
                                 const char *description,
-                                const char *callout_info,
-                                struct key_acl *acl);
+                                const char *callout_info);
 
     This is used to request a key or keyring with a description that matches
     the description specified according to the key type's match_preparse()
@@ -1167,8 +1099,6 @@ payload contents" for more information.
     If successful, the key will have been attached to the default keyring for
     implicitly obtained request-key keys, as set by KEYCTL_SET_REQKEY_KEYRING.
 
-    If a key is created, it will be given the specified ACL.
-
     See also Documentation/security/keys/request-key.rst.
 
 
@@ -1177,8 +1107,7 @@ payload contents" for more information.
         struct key *request_key_tag(const struct key_type *type,
                                     const char *description,
                                     struct key_tag *domain_tag,
-                                    const char *callout_info,
-                                    struct key_acl *acl);
+                                    const char *callout_info);
 
     This is identical to request_key(), except that a domain tag may be
     specifies that causes search algorithm to only match keys matching that
@@ -1193,8 +1122,7 @@ payload contents" for more information.
                                              struct key_tag *domain_tag,
                                              const void *callout_info,
                                              size_t callout_len,
-                                             void *aux,
-                                             struct key_acl *acl);
+                                             void *aux);
 
     This is identical to request_key_tag(), except that the auxiliary data is
     passed to the key_type->request_key() op if it exists, and the
@@ -1267,7 +1195,7 @@ payload contents" for more information.
 
         struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
                                   const struct cred *cred,
-                                  struct key_acl *acl,
+                                  key_perm_t perm,
                                   struct key_restriction *restrict_link,
                                   unsigned long flags,
                                   struct key *dest);
diff --git a/Documentation/security/keys/request-key.rst b/Documentation/security/keys/request-key.rst
index f356fd06c8d5..35f2296b704a 100644
--- a/Documentation/security/keys/request-key.rst
+++ b/Documentation/security/keys/request-key.rst
@@ -11,16 +11,14 @@ The process starts by either the kernel requesting a service by calling
 
         struct key *request_key(const struct key_type *type,
                                 const char *description,
-                                const char *callout_info,
-                                struct key_acl *acl);
+                                const char *callout_info);
 
 or::
 
         struct key *request_key_tag(const struct key_type *type,
                                     const char *description,
                                     const struct key_tag *domain_tag,
-                                    const char *callout_info,
-                                    struct key_acl *acl);
+                                    const char *callout_info);
 
 or::
 
@@ -29,8 +27,7 @@ or::
                                              const struct key_tag *domain_tag,
                                              const char *callout_info,
                                              size_t callout_len,
-                                             void *aux,
-                                             struct key_acl *acl);
+                                             void *aux);
 
 or::