path: root/include/uapi
diff options
authorDavid Howells <dhowells@redhat.com>2019-06-27 23:03:07 +0100
committerDavid Howells <dhowells@redhat.com>2019-06-27 23:03:07 +0100
commit2e12256b9a76584fa3a6da19210509d4775aee36 (patch)
treed25d8a5868dadab6086230223afeb9d26fac001b /include/uapi
parentkeys: Pass the network namespace into request_key mechanism (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 'include/uapi')
1 files changed, 63 insertions, 0 deletions
diff --git a/include/uapi/linux/keyctl.h b/include/uapi/linux/keyctl.h
index ed3d5893830d..e783bf957da8 100644
--- a/include/uapi/linux/keyctl.h
+++ b/include/uapi/linux/keyctl.h
@@ -15,6 +15,69 @@
#include <linux/types.h>
+ * Keyring permission grant definitions
+ */
+enum key_ace_subject_type {
+ KEY_ACE_SUBJ_STANDARD = 0, /* subject is one of key_ace_standard_subject */
+ nr__key_ace_subject_type
+enum key_ace_standard_subject {
+ KEY_ACE_EVERYONE = 0, /* Everyone, including owner and group */
+ KEY_ACE_GROUP = 1, /* The key's group */
+ KEY_ACE_OWNER = 2, /* The owner of the key */
+ KEY_ACE_POSSESSOR = 3, /* Any process that possesses of the key */
+ nr__key_ace_standard_subject
+#define KEY_ACE_VIEW 0x00000001 /* Can describe the key */
+#define KEY_ACE_READ 0x00000002 /* Can read the key content */
+#define KEY_ACE_WRITE 0x00000004 /* Can update/modify the key content */
+#define KEY_ACE_SEARCH 0x00000008 /* Can find the key by search */
+#define KEY_ACE_LINK 0x00000010 /* Can make a link to the key */
+#define KEY_ACE_SET_SECURITY 0x00000020 /* Can set owner, group, ACL */
+#define KEY_ACE_INVAL 0x00000040 /* Can invalidate the key */
+#define KEY_ACE_REVOKE 0x00000080 /* Can revoke the key */
+#define KEY_ACE_JOIN 0x00000100 /* Can join keyring */
+#define KEY_ACE_CLEAR 0x00000200 /* Can clear keyring */
+#define KEY_ACE__PERMS 0xffffffff
+ * Old-style permissions mask, deprecated in favour of ACL.
+ */
+#define KEY_POS_VIEW 0x01000000 /* possessor can view a key's attributes */
+#define KEY_POS_READ 0x02000000 /* possessor can read key payload / view keyring */
+#define KEY_POS_WRITE 0x04000000 /* possessor can update key payload / add link to keyring */
+#define KEY_POS_SEARCH 0x08000000 /* possessor can find a key in search / search a keyring */
+#define KEY_POS_LINK 0x10000000 /* possessor can create a link to a key/keyring */
+#define KEY_POS_SETATTR 0x20000000 /* possessor can set key attributes */
+#define KEY_POS_ALL 0x3f000000
+#define KEY_USR_VIEW 0x00010000 /* user permissions... */
+#define KEY_USR_READ 0x00020000
+#define KEY_USR_WRITE 0x00040000
+#define KEY_USR_SEARCH 0x00080000
+#define KEY_USR_LINK 0x00100000
+#define KEY_USR_SETATTR 0x00200000
+#define KEY_USR_ALL 0x003f0000
+#define KEY_GRP_VIEW 0x00000100 /* group permissions... */
+#define KEY_GRP_READ 0x00000200
+#define KEY_GRP_WRITE 0x00000400
+#define KEY_GRP_SEARCH 0x00000800
+#define KEY_GRP_LINK 0x00001000
+#define KEY_GRP_SETATTR 0x00002000
+#define KEY_GRP_ALL 0x00003f00
+#define KEY_OTH_VIEW 0x00000001 /* third party permissions... */
+#define KEY_OTH_READ 0x00000002
+#define KEY_OTH_WRITE 0x00000004
+#define KEY_OTH_SEARCH 0x00000008
+#define KEY_OTH_LINK 0x00000010
+#define KEY_OTH_SETATTR 0x00000020
+#define KEY_OTH_ALL 0x0000003f
/* special process keyring shortcut IDs */
#define KEY_SPEC_THREAD_KEYRING -1 /* - key ID for thread-specific keyring */
#define KEY_SPEC_PROCESS_KEYRING -2 /* - key ID for process-specific keyring */