linux.git/security/keys/keyring.c, branch v2.6.17

[Security] Keys: Fix oops when adding key to non-keyring

2006-04-10T16:33:46+00:00

This fixes the problem of an oops occuring when a user attempts to add a
key to a non-keyring key [CVE-2006-1522].

The problem is that __keyring_search_one() doesn't check that the
keyring it's been given is actually a keyring.

I've fixed this problem by:

 (1) declaring that caller of __keyring_search_one() must guarantee that
     the keyring is a keyring; and

 (2) making key_create_or_update() check that the keyring is a keyring,
     and return -ENOTDIR if it isn't.

This can be tested by:

	keyctl add user b b `keyctl add user a a @s`

Signed-off-by: David Howells 
Signed-off-by: Linus Torvalds

[PATCH] keys: Permit running process to instantiate keys

2006-01-09T04:13:53+00:00

Make it possible for a running process (such as gssapid) to be able to
instantiate a key, as was requested by Trond Myklebust for NFS4.

The patch makes the following changes:

 (1) A new, optional key type method has been added. This permits a key type
     to intercept requests at the point /sbin/request-key is about to be
     spawned and do something else with them - passing them over the
     rpc_pipefs files or netlink sockets for instance.

     The uninstantiated key, the authorisation key and the intended operation
     name are passed to the method.

 (2) The callout_info is no longer passed as an argument to /sbin/request-key
     to prevent unauthorised viewing of this data using ps or by looking in
     /proc/pid/cmdline.

     This means that the old /sbin/request-key program will not work with the
     patched kernel as it will expect to see an extra argument that is no
     longer there.

     A revised keyutils package will be made available tomorrow.

 (3) The callout_info is now attached to the authorisation key. Reading this
     key will retrieve the information.

 (4) A new field has been added to the task_struct. This holds the
     authorisation key currently active for a thread. Searches now look here
     for the caller's set of keys rather than looking for an auth key in the
     lowest level of the session keyring.

     This permits a thread to be servicing multiple requests at once and to
     switch between them. Note that this is per-thread, not per-process, and
     so is usable in multithreaded programs.

     The setting of this field is inherited across fork and exec.

 (5) A new keyctl function (KEYCTL_ASSUME_AUTHORITY) has been added that
     permits a thread to assume the authority to deal with an uninstantiated
     key. Assumption is only permitted if the authorisation key associated
     with the uninstantiated key is somewhere in the thread's keyrings.

     This function can also clear the assumption.

 (6) A new magic key specifier has been added to refer to the currently
     assumed authorisation key (KEY_SPEC_REQKEY_AUTH_KEY).

 (7) Instantiation will only proceed if the appropriate authorisation key is
     assumed first. The assumed authorisation key is discarded if
     instantiation is successful.

 (8) key_validate() is moved from the file of request_key functions to the
     file of permissions functions.

 (9) The documentation is updated.

From: 

    Build fix.

Signed-off-by: David Howells 
Cc: Trond Myklebust 
Cc: Alexander Zangerl 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] keys: Discard duplicate keys from a keyring on link

2006-01-09T04:13:53+00:00

Cause any links within a keyring to keys that match a key to be linked into
that keyring to be discarded as a link to the new key is added.  The match is
contingent on the type and description strings being the same.

This permits requests, adds and searches to displace negative, expired,
revoked and dead keys easily.  After some discussion it was concluded that
duplicate valid keys should probably be discarded also as they would otherwise
hide the new key.

Since request_key() is intended to be the primary method by which keys are
added to a keyring, duplicate valid keys wouldn't be an issue there as that
function would return an existing match in preference to creating a new key.

Signed-off-by: David Howells 
Cc: Trond Myklebust 
Cc: Alexander Zangerl 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] security/: possible cleanups

2006-01-06T16:33:30+00:00

make needlessly global code static

Signed-off-by: Adrian Bunk 
Cc: David Howells 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Keys: Remove key duplication

2006-01-06T16:33:29+00:00

Remove the key duplication stuff since there's nothing that uses it, no way
to get at it and it's awkward to deal with for LSM purposes.

Signed-off-by: David Howells 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Keys: Fix permissions check for update vs add

2005-12-01T23:48:56+00:00

Permit add_key() to once again update a matching key rather than adding a
new one if a matching key already exists in the target keyring.

This bug causes add_key() to always add a new key, displacing the old from
the target keyring.

Signed-off-by: David Howells 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Keys: Remove incorrect and obsolete '!' operators

2005-11-07T15:53:37+00:00

The attached patch removes a couple of incorrect and obsolete '!' operators
left over from the conversion of the key permission functions from
true/false returns to zero/error returns.

Signed-Off-By: David Howells 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Keys: Add LSM hooks for key management [try #3]

2005-10-31T01:37:23+00:00

The attached patch adds LSM hooks for key management facilities. The notable
changes are:

 (1) The key struct now supports a security pointer for the use of security
     modules. This will permit key labelling and restrictions on which
     programs may access a key.

 (2) Security modules get a chance to note (or abort) the allocation of a key.

 (3) The key permission checking can now be enhanced by the security modules;
     the permissions check consults LSM if all other checks bear out.

 (4) The key permissions checking functions now return an error code rather
     than a boolean value.

 (5) An extra permission has been added to govern the modification of
     attributes (UID, GID, permissions).

Note that there isn't an LSM hook specifically for each keyctl() operation,
but rather the permissions hook allows control of individual operations based
on the permission request bits.

Key management access control through LSM is enabled by automatically if both
CONFIG_KEYS and CONFIG_SECURITY are enabled.

This should be applied on top of the patch ensubjected:

	[PATCH] Keys: Possessor permissions should be additive

Signed-Off-By: David Howells 
Signed-off-by: Chris Wright 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Keys: Add possessor permissions to keys [try #3]

2005-09-28T16:10:47+00:00

The attached patch adds extra permission grants to keys for the possessor of a
key in addition to the owner, group and other permissions bits. This makes
SUID binaries easier to support without going as far as labelling keys and key
targets using the LSM facilities.

This patch adds a second "pointer type" to key structures (struct key_ref *)
that can have the bottom bit of the address set to indicate the possession of
a key. This is propagated through searches from the keyring to the discovered
key. It has been made a separate type so that the compiler can spot attempts
to dereference a potentially incorrect pointer.

The "possession" attribute can't be attached to a key structure directly as
it's not an intrinsic property of a key.

Pointers to keys have been replaced with struct key_ref *'s wherever
possession information needs to be passed through.

This does assume that the bottom bit of the pointer will always be zero on
return from kmem_cache_alloc().

The key reference type has been made into a typedef so that at least it can be
located in the sources, even though it's basically a pointer to an undefined
type. I've also renamed the accessor functions to be more useful, and all
reference variables should now end in "_ref".

Signed-Off-By: David Howells 
Signed-off-by: Linus Torvalds

[PATCH] Destruction of failed keyring oopses

2005-08-04T20:11:14+00:00

The attached patch makes sure that a keyring that failed to instantiate
properly is destroyed without oopsing [CAN-2005-2099].

The problem occurs in three stages:

 (1) The key allocator initialises the type-specific data to all zeroes. In
     the case of a keyring, this will become a link in the keyring name list
     when the keyring is instantiated.

 (2) If a user (any user) attempts to add a keyring with anything other than
     an empty payload, the keyring instantiation function will fail with an
     error and won't add the keyring to the name list.

 (3) The keyring's destructor then sees that the keyring has a description
     (name) and tries to remove the keyring from the name list, which oopses
     because the link pointers are both zero.

This bug permits any user to take down a box trivially.

Signed-Off-By: David Howells 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds