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

This reverts merge 0f75ef6 (and thus
effectively commits

   7a1ade8 ("keys: Provide KEYCTL_GRANT_PERMISSION")
   2e12256 ("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/[email protected]/
 [2] https://lore.kernel.org/lkml/[email protected]/

Link: https://lore.kernel.org/lkml/CAHk-=wjxoeMJfeBahnWH=9zShKp2bsVy527vo3_y8HfOdhwAAw@mail.gmail.com/
Reported-by: Eric Biggers <[email protected]>
Cc: David Howells <[email protected]>
Cc: James Morris <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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torvalds committed Jul 11, 2019
1 parent e9a83bd commit 028db3e
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128 changes: 28 additions & 100 deletions Documentation/security/keys/core.rst
Original file line number Diff line number Diff line change
Expand Up @@ -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.
Expand Down Expand Up @@ -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
===============
Expand Down Expand Up @@ -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()
Expand All @@ -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.


Expand All @@ -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
Expand All @@ -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
Expand Down Expand Up @@ -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);
Expand Down
9 changes: 3 additions & 6 deletions Documentation/security/keys/request-key.rst
Original file line number Diff line number Diff line change
Expand Up @@ -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::

Expand All @@ -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::

Expand Down
7 changes: 5 additions & 2 deletions certs/blacklist.c
Original file line number Diff line number Diff line change
Expand Up @@ -89,7 +89,8 @@ int mark_hash_blacklisted(const char *hash)
hash,
NULL,
0,
&internal_key_acl,
((KEY_POS_ALL & ~KEY_POS_SETATTR) |
KEY_USR_VIEW),
KEY_ALLOC_NOT_IN_QUOTA |
KEY_ALLOC_BUILT_IN);
if (IS_ERR(key)) {
Expand Down Expand Up @@ -148,7 +149,9 @@ static int __init blacklist_init(void)
keyring_alloc(".blacklist",
KUIDT_INIT(0), KGIDT_INIT(0),
current_cred(),
&internal_keyring_acl,
(KEY_POS_ALL & ~KEY_POS_SETATTR) |
KEY_USR_VIEW | KEY_USR_READ |
KEY_USR_SEARCH,
KEY_ALLOC_NOT_IN_QUOTA |
KEY_FLAG_KEEP,
NULL, NULL);
Expand Down
12 changes: 9 additions & 3 deletions certs/system_keyring.c
Original file line number Diff line number Diff line change
Expand Up @@ -99,7 +99,9 @@ static __init int system_trusted_keyring_init(void)
builtin_trusted_keys =
keyring_alloc(".builtin_trusted_keys",
KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
&internal_key_acl, KEY_ALLOC_NOT_IN_QUOTA,
((KEY_POS_ALL & ~KEY_POS_SETATTR) |
KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH),
KEY_ALLOC_NOT_IN_QUOTA,
NULL, NULL);
if (IS_ERR(builtin_trusted_keys))
panic("Can't allocate builtin trusted keyring\n");
Expand All @@ -108,7 +110,10 @@ static __init int system_trusted_keyring_init(void)
secondary_trusted_keys =
keyring_alloc(".secondary_trusted_keys",
KUIDT_INIT(0), KGIDT_INIT(0), current_cred(),
&internal_writable_keyring_acl, KEY_ALLOC_NOT_IN_QUOTA,
((KEY_POS_ALL & ~KEY_POS_SETATTR) |
KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH |
KEY_USR_WRITE),
KEY_ALLOC_NOT_IN_QUOTA,
get_builtin_and_secondary_restriction(),
NULL);
if (IS_ERR(secondary_trusted_keys))
Expand Down Expand Up @@ -158,7 +163,8 @@ static __init int load_system_certificate_list(void)
NULL,
p,
plen,
&internal_key_acl,
((KEY_POS_ALL & ~KEY_POS_SETATTR) |
KEY_USR_VIEW | KEY_USR_READ),
KEY_ALLOC_NOT_IN_QUOTA |
KEY_ALLOC_BUILT_IN |
KEY_ALLOC_BYPASS_RESTRICTION);
Expand Down
2 changes: 1 addition & 1 deletion drivers/md/dm-crypt.c
Original file line number Diff line number Diff line change
Expand Up @@ -2035,7 +2035,7 @@ static int crypt_set_keyring_key(struct crypt_config *cc, const char *key_string
return -ENOMEM;

key = request_key(key_string[0] == 'l' ? &key_type_logon : &key_type_user,
key_desc + 1, NULL, NULL);
key_desc + 1, NULL);
if (IS_ERR(key)) {
kzfree(new_key_string);
return PTR_ERR(key);
Expand Down
2 changes: 1 addition & 1 deletion drivers/nvdimm/security.c
Original file line number Diff line number Diff line change
Expand Up @@ -55,7 +55,7 @@ static struct key *nvdimm_request_key(struct nvdimm *nvdimm)
struct device *dev = &nvdimm->dev;

sprintf(desc, "%s%s", NVDIMM_PREFIX, nvdimm->dimm_id);
key = request_key(&key_type_encrypted, desc, "", NULL);
key = request_key(&key_type_encrypted, desc, "");
if (IS_ERR(key)) {
if (PTR_ERR(key) == -ENOKEY)
dev_dbg(dev, "request_key() found no key\n");
Expand Down
2 changes: 1 addition & 1 deletion fs/afs/security.c
Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@ struct key *afs_request_key(struct afs_cell *cell)

_debug("key %s", cell->anonymous_key->description);
key = request_key(&key_type_rxrpc, cell->anonymous_key->description,
NULL, NULL);
NULL);
if (IS_ERR(key)) {
if (PTR_ERR(key) != -ENOKEY) {
_leave(" = %ld", PTR_ERR(key));
Expand Down
25 changes: 3 additions & 22 deletions fs/cifs/cifs_spnego.c
Original file line number Diff line number Diff line change
Expand Up @@ -32,25 +32,6 @@
#include "cifsproto.h"
static const struct cred *spnego_cred;

static struct key_acl cifs_spnego_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 cifs_spnego_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 | KEY_ACE_CLEAR),
}
};

/* create a new cifs key */
static int
cifs_spnego_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
Expand Down Expand Up @@ -189,8 +170,7 @@ cifs_get_spnego_key(struct cifs_ses *sesInfo)

cifs_dbg(FYI, "key description = %s\n", description);
saved_cred = override_creds(spnego_cred);
spnego_key = request_key(&cifs_spnego_key_type, description, "",
&cifs_spnego_key_acl);
spnego_key = request_key(&cifs_spnego_key_type, description, "");
revert_creds(saved_cred);

#ifdef CONFIG_CIFS_DEBUG2
Expand Down Expand Up @@ -227,7 +207,8 @@ init_cifs_spnego(void)

keyring = keyring_alloc(".cifs_spnego",
GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, cred,
&cifs_spnego_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);
Expand Down
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