Commit Graph

14 Commits

Author SHA1 Message Date
David Howells 7e047ef5fe [PATCH] keys: sort out key quota system
Add the ability for key creation to overrun the user's quota in some
circumstances - notably when a session keyring is created and assigned to a
process that didn't previously have one.

This means it's still possible to log in, should PAM require the creation of a
new session keyring, and fix an overburdened key quota.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26 09:58:18 -07:00
David Howells 04c567d931 [PATCH] Keys: Fix race between two instantiators of a key
Add a revocation notification method to the key type and calls it whilst
the key's semaphore is still write-locked after setting the revocation
flag.

The patch then uses this to maintain a reference on the task_struct of the
process that calls request_key() for as long as the authorisation key
remains unrevoked.

This fixes a potential race between two processes both of which have
assumed the authority to instantiate a key (one may have forked the other
for example).  The problem is that there's no locking around the check for
revocation of the auth key and the use of the task_struct it points to, nor
does the auth key keep a reference on the task_struct.

Access to the "context" pointer in the auth key must thenceforth be done
with the auth key semaphore held.  The revocation method is called with the
target key semaphore held write-locked and the search of the context
process's keyrings is done with the auth key semaphore read-locked.

The check for the revocation state of the auth key just prior to searching
it is done after the auth key is read-locked for the search.  This ensures
that the auth key can't be revoked between the check and the search.

The revocation notification method is added so that the context task_struct
can be released as soon as instantiation happens rather than waiting for
the auth key to be destroyed, thus avoiding the unnecessary pinning of the
requesting process.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-22 15:05:56 -07:00
Michael LeMay d720024e94 [PATCH] selinux: add hooks for key subsystem
Introduce SELinux hooks to support the access key retention subsystem
within the kernel.  Incorporate new flask headers from a modified version
of the SELinux reference policy, with support for the new security class
representing retained keys.  Extend the "key_alloc" security hook with a
task parameter representing the intended ownership context for the key
being allocated.  Attach security information to root's default keyrings
within the SELinux initialization routine.

Has passed David's testsuite.

Signed-off-by: Michael LeMay <mdlemay@epoch.ncsc.mil>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
Acked-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-22 15:05:55 -07:00
David Howells 1a26feb962 [PATCH] Keys: Improve usage of memory barriers and remove IRQ disablement
Remove an unnecessary memory barrier (implicit in rcu_dereference()) from
install_session_keyring().

install_session_keyring() is also rearranged a little to make it slightly
more efficient.

As install_*_keyring() may schedule (in synchronize_rcu() or
keyring_alloc()), they may not be entered with interrupts disabled - and so
there's no point saving the interrupt disablement state over the critical
section.

exec_keys() will also be invoked with interrupts enabled, and so that doesn't
need to save the interrupt state either.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-04-11 06:18:45 -07:00
Ingo Molnar bb0030797f [PATCH] sem2mutex: security/
Semaphore to mutex conversion.

The conversion was generated via scripts, and the result was validated
automatically via a script as well.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Stephen Smalley <sds@epoch.ncsc.mil>
Cc: James Morris <jmorris@namei.org>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-22 07:54:06 -08:00
David Howells b5f545c880 [PATCH] keys: Permit running process to instantiate keys
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: <Valdis.Kletnieks@vt.edu>

    Build fix.

Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Alexander Zangerl <az@bond.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 20:13:53 -08:00
David Howells 29db919063 [PATCH] Keys: Add LSM hooks for key management [try #3]
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 <dhowells@redhat.com>
Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-30 17:37:23 -08:00
David Howells 664cceb009 [PATCH] Keys: Add possessor permissions to keys [try #3]
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 <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-28 09:10:47 -07:00
David Howells bcf945d36f [PATCH] Error during attempt to join key management session can leave semaphore pinned
The attached patch prevents an error during the key session joining operation
from hanging future joins in the D state [CAN-2005-2098].

The problem is that the error handling path for the KEYCTL_JOIN_SESSION_KEYRING
operation has one error path that doesn't release the session management
semaphore. Further attempts to get the semaphore will then sleep for ever in
the D state.

This can happen in four situations, all involving an attempt to allocate a new
session keyring:

 (1) ENOMEM.

 (2) The users key quota being reached.

 (3) A keyring name that is an empty string.

 (4) A keyring name that is too long.

Any user may attempt this operation, and so any user can cause the problem to
occur.

Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-08-04 13:11:14 -07:00
Paul E. McKenney b2b1866006 [PATCH] RCU: clean up a few remaining synchronize_kernel() calls
2.6.12-rc6-mm1 has a few remaining synchronize_kernel()s, some (but not
all) in comments.  This patch changes these synchronize_kernel() calls (and
comments) to synchronize_rcu() or synchronize_sched() as follows:

- arch/x86_64/kernel/mce.c mce_read(): change to synchronize_sched() to
  handle races with machine-check exceptions (synchronize_rcu() would not cut
  it given RCU implementations intended for hardcore realtime use.

- drivers/input/serio/i8042.c i8042_stop(): change to synchronize_sched() to
  handle races with i8042_interrupt() interrupt handler.  Again,
  synchronize_rcu() would not cut it given RCU implementations intended for
  hardcore realtime use.

- include/*/kdebug.h comments: change to synchronize_sched() to handle races
  with NMIs.  As before, synchronize_rcu() would not cut it...

- include/linux/list.h comment: change to synchronize_rcu(), since this
  comment is for list_del_rcu().

- security/keys/key.c unregister_key_type(): change to synchronize_rcu(),
  since this is interacting with RCU read side.

- security/keys/process_keys.c install_session_keyring(): change to
  synchronize_rcu(), since this is interacting with RCU read side.

Signed-off-by: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-25 16:24:38 -07:00
David Howells 3e30148c3d [PATCH] Keys: Make request-key create an authorisation key
The attached patch makes the following changes:

 (1) There's a new special key type called ".request_key_auth".

     This is an authorisation key for when one process requests a key and
     another process is started to construct it. This type of key cannot be
     created by the user; nor can it be requested by kernel services.

     Authorisation keys hold two references:

     (a) Each refers to a key being constructed. When the key being
     	 constructed is instantiated the authorisation key is revoked,
     	 rendering it of no further use.

     (b) The "authorising process". This is either:

     	 (i) the process that called request_key(), or:

     	 (ii) if the process that called request_key() itself had an
     	      authorisation key in its session keyring, then the authorising
     	      process referred to by that authorisation key will also be
     	      referred to by the new authorisation key.

	 This means that the process that initiated a chain of key requests
	 will authorise the lot of them, and will, by default, wind up with
	 the keys obtained from them in its keyrings.

 (2) request_key() creates an authorisation key which is then passed to
     /sbin/request-key in as part of a new session keyring.

 (3) When request_key() is searching for a key to hand back to the caller, if
     it comes across an authorisation key in the session keyring of the
     calling process, it will also search the keyrings of the process
     specified therein and it will use the specified process's credentials
     (fsuid, fsgid, groups) to do that rather than the calling process's
     credentials.

     This allows a process started by /sbin/request-key to find keys belonging
     to the authorising process.

 (4) A key can be read, even if the process executing KEYCTL_READ doesn't have
     direct read or search permission if that key is contained within the
     keyrings of a process specified by an authorisation key found within the
     calling process's session keyring, and is searchable using the
     credentials of the authorising process.

     This allows a process started by /sbin/request-key to read keys belonging
     to the authorising process.

 (5) The magic KEY_SPEC_*_KEYRING key IDs when passed to KEYCTL_INSTANTIATE or
     KEYCTL_NEGATE will specify a keyring of the authorising process, rather
     than the process doing the instantiation.

 (6) One of the process keyrings can be nominated as the default to which
     request_key() should attach new keys if not otherwise specified. This is
     done with KEYCTL_SET_REQKEY_KEYRING and one of the KEY_REQKEY_DEFL_*
     constants. The current setting can also be read using this call.

 (7) request_key() is partially interruptible. If it is waiting for another
     process to finish constructing a key, it can be interrupted. This permits
     a request-key cycle to be broken without recourse to rebooting.

Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-Off-By: Benoit Boissinot <benoit.boissinot@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-24 00:05:19 -07:00
David Howells 8589b4e00e [PATCH] Keys: Use RCU to manage session keyring pointer
The attached patch uses RCU to manage the session keyring pointer in struct
signal_struct.  This means that searching need not disable interrupts and get
a the sighand spinlock to access this pointer.  Furthermore, by judicious use
of rcu_read_(un)lock(), this patch also avoids the need to take and put
refcounts on the session keyring itself, thus saving on even more atomic ops.

Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-24 00:05:18 -07:00
David Howells 76d8aeabfe [PATCH] keys: Discard key spinlock and use RCU for key payload
The attached patch changes the key implementation in a number of ways:

 (1) It removes the spinlock from the key structure.

 (2) The key flags are now accessed using atomic bitops instead of
     write-locking the key spinlock and using C bitwise operators.

     The three instantiation flags are dealt with with the construction
     semaphore held during the request_key/instantiate/negate sequence, thus
     rendering the spinlock superfluous.

     The key flags are also now bit numbers not bit masks.

 (3) The key payload is now accessed using RCU. This permits the recursive
     keyring search algorithm to be simplified greatly since no locks need be
     taken other than the usual RCU preemption disablement. Searching now does
     not require any locks or semaphores to be held; merely that the starting
     keyring be pinned.

 (4) The keyring payload now includes an RCU head so that it can be disposed
     of by call_rcu(). This requires that the payload be copied on unlink to
     prevent introducing races in copy-down vs search-up.

 (5) The user key payload is now a structure with the data following it. It
     includes an RCU head like the keyring payload and for the same reason. It
     also contains a data length because the data length in the key may be
     changed on another CPU whilst an RCU protected read is in progress on the
     payload. This would then see the supposed RCU payload and the on-key data
     length getting out of sync.

     I'm tempted to drop the key's datalen entirely, except that it's used in
     conjunction with quota management and so is a little tricky to get rid
     of.

 (6) Update the keys documentation.

Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-24 00:05:18 -07:00
Linus Torvalds 1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00