Add a facility whereby proposed new links to be added to a keyring can be
vetted, permitting them to be rejected if necessary. This can be used to
block public keys from which the signature cannot be verified or for which
the signature verification fails. It could also be used to provide
blacklisting.
This affects operations like add_key(), KEYCTL_LINK and KEYCTL_INSTANTIATE.
To this end:
(1) A function pointer is added to the key struct that, if set, points to
the vetting function. This is called as:
int (*restrict_link)(struct key *keyring,
const struct key_type *key_type,
unsigned long key_flags,
const union key_payload *key_payload),
where 'keyring' will be the keyring being added to, key_type and
key_payload will describe the key being added and key_flags[*] can be
AND'ed with KEY_FLAG_TRUSTED.
[*] This parameter will be removed in a later patch when
KEY_FLAG_TRUSTED is removed.
The function should return 0 to allow the link to take place or an
error (typically -ENOKEY, -ENOPKG or -EKEYREJECTED) to reject the
link.
The pointer should not be set directly, but rather should be set
through keyring_alloc().
Note that if called during add_key(), preparse is called before this
method, but a key isn't actually allocated until after this function
is called.
(2) KEY_ALLOC_BYPASS_RESTRICTION is added. This can be passed to
key_create_or_update() or key_instantiate_and_link() to bypass the
restriction check.
(3) KEY_FLAG_TRUSTED_ONLY is removed. The entire contents of a keyring
with this restriction emplaced can be considered 'trustworthy' by
virtue of being in the keyring when that keyring is consulted.
(4) key_alloc() and keyring_alloc() take an extra argument that will be
used to set restrict_link in the new key. This ensures that the
pointer is set before the key is published, thus preventing a window
of unrestrictedness. Normally this argument will be NULL.
(5) As a temporary affair, keyring_restrict_trusted_only() is added. It
should be passed to keyring_alloc() as the extra argument instead of
setting KEY_FLAG_TRUSTED_ONLY on a keyring. This will be replaced in
a later patch with functions that look in the appropriate places for
authoritative keys.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Now that /proc/keys is used by libkeyutils to look up a key by type and
description, we should make it unconditional and remove
CONFIG_DEBUG_PROC_KEYS.
Reported-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Jiri Kosina <jkosina@suse.cz>
Call the ->free_preparse() key type op even after ->preparse() returns an
error as it does cleaning up type stuff.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Sage Weil <sage@redhat.com>
Allow a key type's preparsing routine to set the expiry time for a key.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Sage Weil <sage@redhat.com>
Define a __key_get() wrapper to use rather than atomic_inc() on the key usage
count as this makes it easier to hook in refcount error debugging.
Signed-off-by: David Howells <dhowells@redhat.com>
Use keyring_alloc() to create special keyrings now that it has a permissions
parameter rather than using key_alloc() + key_instantiate_and_link().
Also document and export keyring_alloc() so that modules can use it too.
Signed-off-by: David Howells <dhowells@redhat.com>
Give the key type the opportunity to preparse the payload prior to the
instantiation and update routines being called. This is done with the
provision of two new key type operations:
int (*preparse)(struct key_preparsed_payload *prep);
void (*free_preparse)(struct key_preparsed_payload *prep);
If the first operation is present, then it is called before key creation (in
the add/update case) or before the key semaphore is taken (in the update and
instantiate cases). The second operation is called to clean up if the first
was called.
preparse() is given the opportunity to fill in the following structure:
struct key_preparsed_payload {
char *description;
void *type_data[2];
void *payload;
const void *data;
size_t datalen;
size_t quotalen;
};
Before the preparser is called, the first three fields will have been cleared,
the payload pointer and size will be stored in data and datalen and the default
quota size from the key_type struct will be stored into quotalen.
The preparser may parse the payload in any way it likes and may store data in
the type_data[] and payload fields for use by the instantiate() and update()
ops.
The preparser may also propose a description for the key by attaching it as a
string to the description field. This can be used by passing a NULL or ""
description to the add_key() system call or the key_create_or_update()
function. This cannot work with request_key() as that required the description
to tell the upcall about the key to be created.
This, for example permits keys that store PGP public keys to generate their own
name from the user ID and public key fingerprint in the key.
The instantiate() and update() operations are then modified to look like this:
int (*instantiate)(struct key *key, struct key_preparsed_payload *prep);
int (*update)(struct key *key, struct key_preparsed_payload *prep);
and the new payload data is passed in *prep, whether or not it was preparsed.
Signed-off-by: David Howells <dhowells@redhat.com>
Add support for invalidating a key - which renders it immediately invisible to
further searches and causes the garbage collector to immediately wake up,
remove it from keyrings and then destroy it when it's no longer referenced.
It's better not to do this with keyctl_revoke() as that marks the key to start
returning -EKEYREVOKED to searches when what is actually desired is to have the
key refetched.
To invalidate a key the caller must be granted SEARCH permission by the key.
This may be too strict. It may be better to also permit invalidation if the
caller has any of READ, WRITE or SETATTR permission.
The primary use for this is to evict keys that are cached in special keyrings,
such as the DNS resolver or an ID mapper.
Signed-off-by: David Howells <dhowells@redhat.com>
Pull security subsystem updates for 3.4 from James Morris:
"The main addition here is the new Yama security module from Kees Cook,
which was discussed at the Linux Security Summit last year. Its
purpose is to collect miscellaneous DAC security enhancements in one
place. This also marks a departure in policy for LSM modules, which
were previously limited to being standalone access control systems.
Chromium OS is using Yama, and I believe there are plans for Ubuntu,
at least.
This patchset also includes maintenance updates for AppArmor, TOMOYO
and others."
Fix trivial conflict in <net/sock.h> due to the jumo_label->static_key
rename.
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (38 commits)
AppArmor: Fix location of const qualifier on generated string tables
TOMOYO: Return error if fails to delete a domain
AppArmor: add const qualifiers to string arrays
AppArmor: Add ability to load extended policy
TOMOYO: Return appropriate value to poll().
AppArmor: Move path failure information into aa_get_name and rename
AppArmor: Update dfa matching routines.
AppArmor: Minor cleanup of d_namespace_path to consolidate error handling
AppArmor: Retrieve the dentry_path for error reporting when path lookup fails
AppArmor: Add const qualifiers to generated string tables
AppArmor: Fix oops in policy unpack auditing
AppArmor: Fix error returned when a path lookup is disconnected
KEYS: testing wrong bit for KEY_FLAG_REVOKED
TOMOYO: Fix mount flags checking order.
security: fix ima kconfig warning
AppArmor: Fix the error case for chroot relative path name lookup
AppArmor: fix mapping of META_READ to audit and quiet flags
AppArmor: Fix underflow in xindex calculation
AppArmor: Fix dropping of allowed operations that are force audited
AppArmor: Add mising end of structure test to caps unpacking
...
The kernel contains some special internal keyrings, for instance the DNS
resolver keyring :
2a93faf1 I----- 1 perm 1f030000 0 0 keyring .dns_resolver: empty
It would occasionally be useful to allow the contents of such keyrings to be
flushed by root (cache invalidation).
Allow a flag to be set on a keyring to mark that someone possessing the
sysadmin capability can clear the keyring, even without normal write access to
the keyring.
Set this flag on the special keyrings created by the DNS resolver, the NFS
identity mapper and the CIFS identity mapper.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
move LSM-, credentials-, and keys-related files from Documentation/
to Documentation/security/,
add Documentation/security/00-INDEX, and
update all occurrences of Documentation/<moved_file>
to Documentation/security/<moved_file>.
David Howells