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author | David Howells <dhowells@redhat.com> | 2019-06-28 01:03:07 +0300 |
---|---|---|
committer | David Howells <dhowells@redhat.com> | 2019-06-28 01:03:07 +0300 |
commit | 2e12256b9a76584fa3a6da19210509d4775aee36 (patch) | |
tree | d25d8a5868dadab6086230223afeb9d26fac001b /net | |
parent | a58946c158a040068e7c94dc1d58bbd273258068 (diff) |
keys: Replace uid/gid/perm permissions checking with an ACL
Replace the uid/gid/perm permissions checking on a key with an ACL to allow
the SETATTR and SEARCH permissions to be split. This will also allow a
greater range of subjects to represented.
============
WHY DO THIS?
============
The problem is that SETATTR and SEARCH cover a slew of actions, not all of
which should be grouped together.
For SETATTR, this includes actions that are about controlling access to a
key:
(1) Changing a key's ownership.
(2) Changing a key's security information.
(3) Setting a keyring's restriction.
And actions that are about managing a key's lifetime:
(4) Setting an expiry time.
(5) Revoking a key.
and (proposed) managing a key as part of a cache:
(6) Invalidating a key.
Managing a key's lifetime doesn't really have anything to do with
controlling access to that key.
Expiry time is awkward since it's more about the lifetime of the content
and so, in some ways goes better with WRITE permission. It can, however,
be set unconditionally by a process with an appropriate authorisation token
for instantiating a key, and can also be set by the key type driver when a
key is instantiated, so lumping it with the access-controlling actions is
probably okay.
As for SEARCH permission, that currently covers:
(1) Finding keys in a keyring tree during a search.
(2) Permitting keyrings to be joined.
(3) Invalidation.
But these don't really belong together either, since these actions really
need to be controlled separately.
Finally, there are number of special cases to do with granting the
administrator special rights to invalidate or clear keys that I would like
to handle with the ACL rather than key flags and special checks.
===============
WHAT IS CHANGED
===============
The SETATTR permission is split to create two new permissions:
(1) SET_SECURITY - which allows the key's owner, group and ACL to be
changed and a restriction to be placed on a keyring.
(2) REVOKE - which allows a key to be revoked.
The SEARCH permission is split to create:
(1) SEARCH - which allows a keyring to be search and a key to be found.
(2) JOIN - which allows a keyring to be joined as a session keyring.
(3) INVAL - which allows a key to be invalidated.
The WRITE permission is also split to create:
(1) WRITE - which allows a key's content to be altered and links to be
added, removed and replaced in a keyring.
(2) CLEAR - which allows a keyring to be cleared completely. This is
split out to make it possible to give just this to an administrator.
(3) REVOKE - see above.
Keys acquire ACLs which consist of a series of ACEs, and all that apply are
unioned together. An ACE specifies a subject, such as:
(*) Possessor - permitted to anyone who 'possesses' a key
(*) Owner - permitted to the key owner
(*) Group - permitted to the key group
(*) Everyone - permitted to everyone
Note that 'Other' has been replaced with 'Everyone' on the assumption that
you wouldn't grant a permit to 'Other' that you wouldn't also grant to
everyone else.
Further subjects may be made available by later patches.
The ACE also specifies a permissions mask. The set of permissions is now:
VIEW Can view the key metadata
READ Can read the key content
WRITE Can update/modify the key content
SEARCH Can find the key by searching/requesting
LINK Can make a link to the key
SET_SECURITY Can change owner, ACL, expiry
INVAL Can invalidate
REVOKE Can revoke
JOIN Can join this keyring
CLEAR Can clear this keyring
The KEYCTL_SETPERM function is then deprecated.
The KEYCTL_SET_TIMEOUT function then is permitted if SET_SECURITY is set,
or if the caller has a valid instantiation auth token.
The KEYCTL_INVALIDATE function then requires INVAL.
The KEYCTL_REVOKE function then requires REVOKE.
The KEYCTL_JOIN_SESSION_KEYRING function then requires JOIN to join an
existing keyring.
The JOIN permission is enabled by default for session keyrings and manually
created keyrings only.
======================
BACKWARD COMPATIBILITY
======================
To maintain backward compatibility, KEYCTL_SETPERM will translate the
permissions mask it is given into a new ACL for a key - unless
KEYCTL_SET_ACL has been called on that key, in which case an error will be
returned.
It will convert possessor, owner, group and other permissions into separate
ACEs, if each portion of the mask is non-zero.
SETATTR permission turns on all of INVAL, REVOKE and SET_SECURITY. WRITE
permission turns on WRITE, REVOKE and, if a keyring, CLEAR. JOIN is turned
on if a keyring is being altered.
The KEYCTL_DESCRIBE function translates the ACL back into a permissions
mask to return depending on possessor, owner, group and everyone ACEs.
It will make the following mappings:
(1) INVAL, JOIN -> SEARCH
(2) SET_SECURITY -> SETATTR
(3) REVOKE -> WRITE if SETATTR isn't already set
(4) CLEAR -> WRITE
Note that the value subsequently returned by KEYCTL_DESCRIBE may not match
the value set with KEYCTL_SETATTR.
=======
TESTING
=======
This passes the keyutils testsuite for all but a couple of tests:
(1) tests/keyctl/dh_compute/badargs: The first wrong-key-type test now
returns EOPNOTSUPP rather than ENOKEY as READ permission isn't removed
if the type doesn't have ->read(). You still can't actually read the
key.
(2) tests/keyctl/permitting/valid: The view-other-permissions test doesn't
work as Other has been replaced with Everyone in the ACL.
Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'net')
-rw-r--r-- | net/ceph/ceph_common.c | 2 | ||||
-rw-r--r-- | net/dns_resolver/dns_key.c | 12 | ||||
-rw-r--r-- | net/dns_resolver/dns_query.c | 15 | ||||
-rw-r--r-- | net/rxrpc/key.c | 19 | ||||
-rw-r--r-- | net/wireless/reg.c | 6 |
5 files changed, 40 insertions, 14 deletions
diff --git a/net/ceph/ceph_common.c b/net/ceph/ceph_common.c index 79eac465ec65..d4af93a35e2b 100644 --- a/net/ceph/ceph_common.c +++ b/net/ceph/ceph_common.c @@ -305,7 +305,7 @@ static int get_secret(struct ceph_crypto_key *dst, const char *name) { int err = 0; struct ceph_crypto_key *ckey; - ukey = request_key(&key_type_ceph, name, NULL); + ukey = request_key(&key_type_ceph, name, NULL, NULL); if (IS_ERR(ukey)) { /* request_key errors don't map nicely to mount(2) errors; don't even try, but still printk */ diff --git a/net/dns_resolver/dns_key.c b/net/dns_resolver/dns_key.c index 3e1a90669006..6b201531b165 100644 --- a/net/dns_resolver/dns_key.c +++ b/net/dns_resolver/dns_key.c @@ -46,6 +46,15 @@ const struct cred *dns_resolver_cache; #define DNS_ERRORNO_OPTION "dnserror" +static struct key_acl dns_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), + } +}; + /* * Preparse instantiation data for a dns_resolver key. * @@ -343,8 +352,7 @@ static int __init init_dns_resolver(void) keyring = keyring_alloc(".dns_resolver", GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, cred, - (KEY_POS_ALL & ~KEY_POS_SETATTR) | - KEY_USR_VIEW | KEY_USR_READ, + &dns_keyring_acl, KEY_ALLOC_NOT_IN_QUOTA, NULL, NULL); if (IS_ERR(keyring)) { ret = PTR_ERR(keyring); diff --git a/net/dns_resolver/dns_query.c b/net/dns_resolver/dns_query.c index cab4e0df924f..236baf2bfa4c 100644 --- a/net/dns_resolver/dns_query.c +++ b/net/dns_resolver/dns_query.c @@ -47,6 +47,16 @@ #include "internal.h" +static struct key_acl dns_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 | KEY_ACE_INVAL), + } +}; + /** * dns_query - Query the DNS * @net: The network namespace to operate in. @@ -125,7 +135,8 @@ int dns_query(struct net *net, * add_key() to preinstall malicious redirections */ saved_cred = override_creds(dns_resolver_cache); - rkey = request_key_net(&key_type_dns_resolver, desc, net, options); + rkey = request_key_net(&key_type_dns_resolver, desc, net, options, + &dns_key_acl); revert_creds(saved_cred); kfree(desc); if (IS_ERR(rkey)) { @@ -135,8 +146,6 @@ int dns_query(struct net *net, down_read(&rkey->sem); set_bit(KEY_FLAG_ROOT_CAN_INVAL, &rkey->flags); - rkey->perm |= KEY_USR_VIEW; - ret = key_validate(rkey); if (ret < 0) goto put; diff --git a/net/rxrpc/key.c b/net/rxrpc/key.c index 1cc6b0c6cc42..207d621d18c0 100644 --- a/net/rxrpc/key.c +++ b/net/rxrpc/key.c @@ -27,6 +27,14 @@ #include <keys/user-type.h> #include "ar-internal.h" +static struct key_acl rxrpc_null_key_acl = { + .usage = REFCOUNT_INIT(1), + .nr_ace = 1, + .aces = { + KEY_POSSESSOR_ACE(KEY_ACE_SEARCH | KEY_ACE_READ), + } +}; + static int rxrpc_vet_description_s(const char *); static int rxrpc_preparse(struct key_preparsed_payload *); static int rxrpc_preparse_s(struct key_preparsed_payload *); @@ -914,7 +922,8 @@ int rxrpc_request_key(struct rxrpc_sock *rx, char __user *optval, int optlen) if (IS_ERR(description)) return PTR_ERR(description); - key = request_key_net(&key_type_rxrpc, description, sock_net(&rx->sk), NULL); + key = request_key_net(&key_type_rxrpc, description, sock_net(&rx->sk), + NULL, NULL); if (IS_ERR(key)) { kfree(description); _leave(" = %ld", PTR_ERR(key)); @@ -945,7 +954,8 @@ int rxrpc_server_keyring(struct rxrpc_sock *rx, char __user *optval, if (IS_ERR(description)) return PTR_ERR(description); - key = request_key_net(&key_type_keyring, description, sock_net(&rx->sk), NULL); + key = request_key_net(&key_type_keyring, description, sock_net(&rx->sk), + NULL, NULL); if (IS_ERR(key)) { kfree(description); _leave(" = %ld", PTR_ERR(key)); @@ -978,7 +988,8 @@ int rxrpc_get_server_data_key(struct rxrpc_connection *conn, _enter(""); key = key_alloc(&key_type_rxrpc, "x", - GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, cred, 0, + GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, cred, + &internal_key_acl, KEY_ALLOC_NOT_IN_QUOTA, NULL); if (IS_ERR(key)) { _leave(" = -ENOMEM [alloc %ld]", PTR_ERR(key)); @@ -1026,7 +1037,7 @@ struct key *rxrpc_get_null_key(const char *keyname) key = key_alloc(&key_type_rxrpc, keyname, GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, cred, - KEY_POS_SEARCH, KEY_ALLOC_NOT_IN_QUOTA, NULL); + &rxrpc_null_key_acl, KEY_ALLOC_NOT_IN_QUOTA, NULL); if (IS_ERR(key)) return key; diff --git a/net/wireless/reg.c b/net/wireless/reg.c index 4831ad745f91..298fe91557f7 100644 --- a/net/wireless/reg.c +++ b/net/wireless/reg.c @@ -741,8 +741,7 @@ static void __init load_keys_from_buffer(const u8 *p, unsigned int buflen) key = key_create_or_update(make_key_ref(builtin_regdb_keys, 1), "asymmetric", NULL, p, plen, - ((KEY_POS_ALL & ~KEY_POS_SETATTR) | - KEY_USR_VIEW | KEY_USR_READ), + &internal_key_acl, KEY_ALLOC_NOT_IN_QUOTA | KEY_ALLOC_BUILT_IN | KEY_ALLOC_BYPASS_RESTRICTION); @@ -768,8 +767,7 @@ static int __init load_builtin_regdb_keys(void) builtin_regdb_keys = keyring_alloc(".builtin_regdb_keys", KUIDT_INIT(0), KGIDT_INIT(0), current_cred(), - ((KEY_POS_ALL & ~KEY_POS_SETATTR) | - KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH), + &internal_keyring_acl, KEY_ALLOC_NOT_IN_QUOTA, NULL, NULL); if (IS_ERR(builtin_regdb_keys)) return PTR_ERR(builtin_regdb_keys); |