Commit Graph

73 Commits

Author SHA1 Message Date
David P. Quigley
ddd29ec659 sysfs: Add labeling support for sysfs
This patch adds a setxattr handler to the file, directory, and symlink
inode_operations structures for sysfs. The patch uses hooks introduced in the
previous patch to handle the getting and setting of security information for
the sysfs inodes. As was suggested by Eric Biederman the struct iattr in the
sysfs_dirent structure has been replaced by a structure which contains the
iattr, secdata and secdata length to allow the changes to persist in the event
that the inode representing the sysfs_dirent is evicted. Because sysfs only
stores this information when a change is made all the optional data is moved
into one dynamically allocated field.

This patch addresses an issue where SELinux was denying virtd access to the PCI
configuration entries in sysfs. The lack of setxattr handlers for sysfs
required that a single label be assigned to all entries in sysfs. Granting virtd
access to every entry in sysfs is not an acceptable solution so fine grained
labeling of sysfs is required such that individual entries can be labeled
appropriately.

[sds:  Fixed compile-time warnings, coding style, and setting of inode security init flags.]

Signed-off-by: David P. Quigley <dpquigl@tycho.nsa.gov>
Signed-off-by: Stephen D. Smalley <sds@tycho.nsa.gov>
Signed-off-by: James Morris <jmorris@namei.org>
2009-09-10 10:11:29 +10:00
David P. Quigley
1ee65e37e9 LSM/SELinux: inode_{get,set,notify}secctx hooks to access LSM security context information.
This patch introduces three new hooks. The inode_getsecctx hook is used to get
all relevant information from an LSM about an inode. The inode_setsecctx is
used to set both the in-core and on-disk state for the inode based on a context
derived from inode_getsecctx.The final hook inode_notifysecctx will notify the
LSM of a change for the in-core state of the inode in question. These hooks are
for use in the labeled NFS code and addresses concerns of how to set security
on an inode in a multi-xattr LSM. For historical reasons Stephen Smalley's
explanation of the reason for these hooks is pasted below.

Quote Stephen Smalley

inode_setsecctx:  Change the security context of an inode.  Updates the
in core security context managed by the security module and invokes the
fs code as needed (via __vfs_setxattr_noperm) to update any backing
xattrs that represent the context.  Example usage:  NFS server invokes
this hook to change the security context in its incore inode and on the
backing file system to a value provided by the client on a SETATTR
operation.

inode_notifysecctx:  Notify the security module of what the security
context of an inode should be.  Initializes the incore security context
managed by the security module for this inode.  Example usage:  NFS
client invokes this hook to initialize the security context in its
incore inode to the value provided by the server for the file when the
server returned the file's attributes to the client.

Signed-off-by: David P. Quigley <dpquigl@tycho.nsa.gov>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-09-10 10:11:24 +10:00
David Howells
ee18d64c1f KEYS: Add a keyctl to install a process's session keyring on its parent [try #6]
Add a keyctl to install a process's session keyring onto its parent.  This
replaces the parent's session keyring.  Because the COW credential code does
not permit one process to change another process's credentials directly, the
change is deferred until userspace next starts executing again.  Normally this
will be after a wait*() syscall.

To support this, three new security hooks have been provided:
cred_alloc_blank() to allocate unset security creds, cred_transfer() to fill in
the blank security creds and key_session_to_parent() - which asks the LSM if
the process may replace its parent's session keyring.

The replacement may only happen if the process has the same ownership details
as its parent, and the process has LINK permission on the session keyring, and
the session keyring is owned by the process, and the LSM permits it.

Note that this requires alteration to each architecture's notify_resume path.
This has been done for all arches barring blackfin, m68k* and xtensa, all of
which need assembly alteration to support TIF_NOTIFY_RESUME.  This allows the
replacement to be performed at the point the parent process resumes userspace
execution.

This allows the userspace AFS pioctl emulation to fully emulate newpag() and
the VIOCSETTOK and VIOCSETTOK2 pioctls, all of which require the ability to
alter the parent process's PAG membership.  However, since kAFS doesn't use
PAGs per se, but rather dumps the keys into the session keyring, the session
keyring of the parent must be replaced if, for example, VIOCSETTOK is passed
the newpag flag.

This can be tested with the following program:

	#include <stdio.h>
	#include <stdlib.h>
	#include <keyutils.h>

	#define KEYCTL_SESSION_TO_PARENT	18

	#define OSERROR(X, S) do { if ((long)(X) == -1) { perror(S); exit(1); } } while(0)

	int main(int argc, char **argv)
	{
		key_serial_t keyring, key;
		long ret;

		keyring = keyctl_join_session_keyring(argv[1]);
		OSERROR(keyring, "keyctl_join_session_keyring");

		key = add_key("user", "a", "b", 1, keyring);
		OSERROR(key, "add_key");

		ret = keyctl(KEYCTL_SESSION_TO_PARENT);
		OSERROR(ret, "KEYCTL_SESSION_TO_PARENT");

		return 0;
	}

Compiled and linked with -lkeyutils, you should see something like:

	[dhowells@andromeda ~]$ keyctl show
	Session Keyring
	       -3 --alswrv   4043  4043  keyring: _ses
	355907932 --alswrv   4043    -1   \_ keyring: _uid.4043
	[dhowells@andromeda ~]$ /tmp/newpag
	[dhowells@andromeda ~]$ keyctl show
	Session Keyring
	       -3 --alswrv   4043  4043  keyring: _ses
	1055658746 --alswrv   4043  4043   \_ user: a
	[dhowells@andromeda ~]$ /tmp/newpag hello
	[dhowells@andromeda ~]$ keyctl show
	Session Keyring
	       -3 --alswrv   4043  4043  keyring: hello
	340417692 --alswrv   4043  4043   \_ user: a

Where the test program creates a new session keyring, sticks a user key named
'a' into it and then installs it on its parent.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-09-02 21:29:22 +10:00
Julia Lawall
da34d4248b security/smack: Use AF_INET for sin_family field
Elsewhere the sin_family field holds a value with a name of the form
AF_..., so it seems reasonable to do so here as well.  Also the values of
PF_INET and AF_INET are the same.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
struct sockaddr_in sip;
@@

(
sip.sin_family ==
- PF_INET
+ AF_INET
|
sip.sin_family !=
- PF_INET
+ AF_INET
|
sip.sin_family =
- PF_INET
+ AF_INET
)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-08-06 08:46:15 +10:00
Thomas Liu
d4131ded4d security: Make lsm_priv union in lsm_audit.h anonymous
Made the lsm_priv union in include/linux/lsm_audit.h
anonymous.

Signed-off-by: Thomas Liu <tliu@redhat.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-07-10 08:58:39 +10:00
Thomas Liu
ed5215a214 Move variable function in lsm_audit.h into SMACK private space
Moved variable function in include/linux/lsm_audit.h into the
smack_audit_data struct since it is never used outside of it.

Also removed setting of function in the COMMON_AUDIT_DATA_INIT
macro because that variable is now private to SMACK.

Signed-off-by: Thomas Liu <tliu@redhat.com>
Acked-by: Eric Paris <eparis@redhat.com>
I-dont-see-any-problems-with-it: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-07-10 08:54:14 +10:00
Ingo Molnar
9e48858f7d security: rename ptrace_may_access => ptrace_access_check
The ->ptrace_may_access() methods are named confusingly - the real
ptrace_may_access() returns a bool, while these security checks have
a retval convention.

Rename it to ptrace_access_check, to reduce the confusion factor.

[ Impact: cleanup, no code changed ]

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: James Morris <jmorris@namei.org>
2009-06-25 00:18:05 +10:00
Linus Torvalds
3296ca27f5 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6: (44 commits)
  nommu: Provide mmap_min_addr definition.
  TOMOYO: Add description of lists and structures.
  TOMOYO: Remove unused field.
  integrity: ima audit dentry_open failure
  TOMOYO: Remove unused parameter.
  security: use mmap_min_addr indepedently of security models
  TOMOYO: Simplify policy reader.
  TOMOYO: Remove redundant markers.
  SELinux: define audit permissions for audit tree netlink messages
  TOMOYO: Remove unused mutex.
  tomoyo: avoid get+put of task_struct
  smack: Remove redundant initialization.
  integrity: nfsd imbalance bug fix
  rootplug: Remove redundant initialization.
  smack: do not beyond ARRAY_SIZE of data
  integrity: move ima_counts_get
  integrity: path_check update
  IMA: Add __init notation to ima functions
  IMA: Minimal IMA policy and boot param for TCB IMA policy
  selinux: remove obsolete read buffer limit from sel_read_bool
  ...
2009-06-11 10:01:41 -07:00
Linus Torvalds
20f3f3ca49 Merge branch 'rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  rcu: rcu_sched_grace_period(): kill the bogus flush_signals()
  rculist: use list_entry_rcu in places where it's appropriate
  rculist.h: introduce list_entry_rcu() and list_first_entry_rcu()
  rcu: Update RCU tracing documentation for __rcu_pending
  rcu: Add __rcu_pending tracing to hierarchical RCU
  RCU: make treercu be default
2009-06-10 19:50:03 -07:00
Tetsuo Handa
13b297d943 smack: Remove redundant initialization.
We don't need to explicitly initialize to cap_* because
it will be filled by security_fixup_ops().

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-05-28 11:57:09 +10:00
Roel Kluin
6470c077ca smack: do not beyond ARRAY_SIZE of data
Do not go beyond ARRAY_SIZE of data

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-05-22 12:34:48 +10:00
James Morris
d254117099 Merge branch 'master' into next 2009-05-08 17:56:47 +10:00
Etienne Basset
defc433ba3 Smack: check for SMACK xattr validity in smack_inode_setxattr
the following patch moves checks for SMACK xattr validity
from smack_inode_post_setxattr (which cannot return an error to the user)
to smack_inode_setxattr (which can return an error).

Signed-off-by: Etienne Basset <etienne.basset@numericable.fr>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-04-18 12:58:25 +10:00
Jiri Pirko
05725f7eb4 rculist: use list_entry_rcu in places where it's appropriate
Use previously introduced list_entry_rcu instead of an open-coded
list_entry + rcu_dereference combination.

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: dipankar@in.ibm.com
LKML-Reference: <20090414181715.GA3634@psychotron.englab.brq.redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-04-15 12:05:25 +02:00
Etienne Basset
ecfcc53fef smack: implement logging V3
the following patch, add logging of Smack security decisions.
This is of course very useful to understand what your current smack policy does.
As suggested by Casey, it also now forbids labels with ', " or \

It introduces a '/smack/logging' switch :
0: no logging
1: log denied (default)
2: log accepted
3: log denied&accepted

Signed-off-by: Etienne Basset <etienne.basset@numericable.fr>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-04-14 09:00:23 +10:00
Etienne Basset
4303154e86 smack: Add a new '-CIPSO' option to the network address label configuration
This patch adds a new special option '-CIPSO' to the Smack subsystem. When used
in the netlabel list, it means "use CIPSO networking". A use case is when your
local network speaks CIPSO and you want also to connect to the unlabeled
Internet. This patch also add some documentation describing that. The patch
also corrects an oops when setting a '' SMACK64 xattr to a file.

Signed-off-by: Etienne Basset <etienne.basset@numericable.fr>
Signed-off-by: Paul Moore <paul.moore@hp.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-03-28 15:01:37 +11:00
Paul Moore
07feee8f81 netlabel: Cleanup the Smack/NetLabel code to fix incoming TCP connections
This patch cleans up a lot of the Smack network access control code.  The
largest changes are to fix the labeling of incoming TCP connections in a
manner similar to the recent SELinux changes which use the
security_inet_conn_request() hook to label the request_sock and let the label
move to the child socket via the normal network stack mechanisms.  In addition
to the incoming TCP connection fixes this patch also removes the smk_labled
field from the socket_smack struct as the minor optimization advantage was
outweighed by the difficulty in maintaining it's proper state.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-03-28 15:01:37 +11:00
Paul Moore
389fb800ac netlabel: Label incoming TCP connections correctly in SELinux
The current NetLabel/SELinux behavior for incoming TCP connections works but
only through a series of happy coincidences that rely on the limited nature of
standard CIPSO (only able to convey MLS attributes) and the write equality
imposed by the SELinux MLS constraints.  The problem is that network sockets
created as the result of an incoming TCP connection were not on-the-wire
labeled based on the security attributes of the parent socket but rather based
on the wire label of the remote peer.  The issue had to do with how IP options
were managed as part of the network stack and where the LSM hooks were in
relation to the code which set the IP options on these newly created child
sockets.  While NetLabel/SELinux did correctly set the socket's on-the-wire
label it was promptly cleared by the network stack and reset based on the IP
options of the remote peer.

This patch, in conjunction with a prior patch that adjusted the LSM hook
locations, works to set the correct on-the-wire label format for new incoming
connections through the security_inet_conn_request() hook.  Besides the
correct behavior there are many advantages to this change, the most significant
is that all of the NetLabel socket labeling code in SELinux now lives in hooks
which can return error codes to the core stack which allows us to finally get
ride of the selinux_netlbl_inode_permission() logic which greatly simplfies
the NetLabel/SELinux glue code.  In the process of developing this patch I
also ran into a small handful of AF_INET6 cleanliness issues that have been
fixed which should make the code safer and easier to extend in the future.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-03-28 15:01:36 +11:00
Etienne Basset
7198e2eeb4 smack: convert smack to standard linux lists
the following patch (on top of 2.6.29) converts Smack lists to standard linux lists
Please review and consider for inclusion in 2.6.30-rc

regards,
Etienne

Signed-off-by: Etienne Basset <etienne.basset@numericable.fr>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
2009-03-26 09:17:04 +11:00
James Morris
703a3cd728 Merge branch 'master' into next 2009-03-24 10:52:46 +11:00
etienne
211a40c087 smack: fixes for unlabeled host support
The following patch (against 2.6.29rc5) fixes a few issues in the
smack/netlabel "unlabeled host support" functionnality that was added in
2.6.29rc.  It should go in before -final.

1) smack_host_label disregard a "0.0.0.0/0 @" rule (or other label),
preventing 'tagged' tasks to access Internet (many systems drop packets with
IP options)

2) netmasks were not handled correctly, they were stored in a way _not
equivalent_ to conversion to be32 (it was equivalent for /0, /8, /16, /24,
/32 masks but not other masks)

3) smack_netlbladdr prefixes (IP/mask) were not consistent (mask&IP was not
done), so there could have been different list entries for the same IP
prefix; if those entries had different labels, well ...

4) they were not sorted

1) 2) 3) are bugs, 4) is a more cosmetic issue.
The patch :

-creates a new helper smk_netlbladdr_insert to insert a smk_netlbladdr,
-sorted by netmask length

-use the new sorted nature of  smack_netlbladdrs list to simplify
 smack_host_label : the first match _will_ be the more specific

-corrects endianness issues in smk_write_netlbladdr &  netlbladdr_seq_show

Signed-off-by: <etienne.basset@numericable.fr>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-03-05 08:36:34 +11:00
etienne
113a0e4590 smack: fixes for unlabeled host support
The following patch (against 2.6.29rc5) fixes a few issues in the
smack/netlabel "unlabeled host support" functionnality that was added in
2.6.29rc.  It should go in before -final.

1) smack_host_label disregard a "0.0.0.0/0 @" rule (or other label),
preventing 'tagged' tasks to access Internet (many systems drop packets with
IP options)

2) netmasks were not handled correctly, they were stored in a way _not
equivalent_ to conversion to be32 (it was equivalent for /0, /8, /16, /24,
/32 masks but not other masks)

3) smack_netlbladdr prefixes (IP/mask) were not consistent (mask&IP was not
done), so there could have been different list entries for the same IP
prefix; if those entries had different labels, well ...

4) they were not sorted

1) 2) 3) are bugs, 4) is a more cosmetic issue.
The patch :

-creates a new helper smk_netlbladdr_insert to insert a smk_netlbladdr,
-sorted by netmask length

-use the new sorted nature of  smack_netlbladdrs list to simplify
 smack_host_label : the first match _will_ be the more specific

-corrects endianness issues in smk_write_netlbladdr &  netlbladdr_seq_show

Signed-off-by: <etienne.basset@numericable.fr>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-03-05 08:30:01 +11:00
Randy Dunlap
251a2a958b smack: fix lots of kernel-doc notation
Fix/add kernel-doc notation and fix typos in security/smack/.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-02-19 15:51:10 +11:00
Casey Schaufler
152a649b64 smackfs load append mode fix
Given just how hard it is to find the code that uses MAY_APPEND
it's probably not a big surprise that this went unnoticed for so
long. The Smack rules loading code is incorrectly setting the
MAY_READ bit when MAY_APPEND is requested.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: James Morris <jmorris@namei.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-27 20:13:32 -08:00
Fernando Carrijo
c19a28e119 remove lots of double-semicolons
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Theodore Ts'o <tytso@mit.edu>
Acked-by: Mark Fasheh <mfasheh@suse.com>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: James Morris <jmorris@namei.org>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-08 08:31:14 -08:00
James Morris
ac8cc0fa53 Merge branch 'next' into for-linus 2009-01-07 09:58:22 +11:00
James Morris
29881c4502 Revert "CRED: Fix regression in cap_capable() as shown up by sys_faccessat() [ver #2]"
This reverts commit 14eaddc967.

David has a better version to come.
2009-01-07 09:21:54 +11:00
David Howells
14eaddc967 CRED: Fix regression in cap_capable() as shown up by sys_faccessat() [ver #2]
Fix a regression in cap_capable() due to:

	commit 5ff7711e635b32f0a1e558227d030c7e45b4a465
	Author: David Howells <dhowells@redhat.com>
	Date:   Wed Dec 31 02:52:28 2008 +0000

	    CRED: Differentiate objective and effective subjective credentials on a task

The problem is that the above patch allows a process to have two sets of
credentials, and for the most part uses the subjective credentials when
accessing current's creds.

There is, however, one exception: cap_capable(), and thus capable(), uses the
real/objective credentials of the target task, whether or not it is the current
task.

Ordinarily this doesn't matter, since usually the two cred pointers in current
point to the same set of creds.  However, sys_faccessat() makes use of this
facility to override the credentials of the calling process to make its test,
without affecting the creds as seen from other processes.

One of the things sys_faccessat() does is to make an adjustment to the
effective capabilities mask, which cap_capable(), as it stands, then ignores.

The affected capability check is in generic_permission():

	if (!(mask & MAY_EXEC) || execute_ok(inode))
		if (capable(CAP_DAC_OVERRIDE))
			return 0;

This change splits capable() from has_capability() down into the commoncap and
SELinux code.  The capable() security op now only deals with the current
process, and uses the current process's subjective creds.  A new security op -
task_capable() - is introduced that can check any task's objective creds.

strictly the capable() security op is superfluous with the presence of the
task_capable() op, however it should be faster to call the capable() op since
two fewer arguments need be passed down through the various layers.

This can be tested by compiling the following program from the XFS testsuite:

/*
 *  t_access_root.c - trivial test program to show permission bug.
 *
 *  Written by Michael Kerrisk - copyright ownership not pursued.
 *  Sourced from: http://linux.derkeiler.com/Mailing-Lists/Kernel/2003-10/6030.html
 */
#include <limits.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/stat.h>

#define UID 500
#define GID 100
#define PERM 0
#define TESTPATH "/tmp/t_access"

static void
errExit(char *msg)
{
    perror(msg);
    exit(EXIT_FAILURE);
} /* errExit */

static void
accessTest(char *file, int mask, char *mstr)
{
    printf("access(%s, %s) returns %d\n", file, mstr, access(file, mask));
} /* accessTest */

int
main(int argc, char *argv[])
{
    int fd, perm, uid, gid;
    char *testpath;
    char cmd[PATH_MAX + 20];

    testpath = (argc > 1) ? argv[1] : TESTPATH;
    perm = (argc > 2) ? strtoul(argv[2], NULL, 8) : PERM;
    uid = (argc > 3) ? atoi(argv[3]) : UID;
    gid = (argc > 4) ? atoi(argv[4]) : GID;

    unlink(testpath);

    fd = open(testpath, O_RDWR | O_CREAT, 0);
    if (fd == -1) errExit("open");

    if (fchown(fd, uid, gid) == -1) errExit("fchown");
    if (fchmod(fd, perm) == -1) errExit("fchmod");
    close(fd);

    snprintf(cmd, sizeof(cmd), "ls -l %s", testpath);
    system(cmd);

    if (seteuid(uid) == -1) errExit("seteuid");

    accessTest(testpath, 0, "0");
    accessTest(testpath, R_OK, "R_OK");
    accessTest(testpath, W_OK, "W_OK");
    accessTest(testpath, X_OK, "X_OK");
    accessTest(testpath, R_OK | W_OK, "R_OK | W_OK");
    accessTest(testpath, R_OK | X_OK, "R_OK | X_OK");
    accessTest(testpath, W_OK | X_OK, "W_OK | X_OK");
    accessTest(testpath, R_OK | W_OK | X_OK, "R_OK | W_OK | X_OK");

    exit(EXIT_SUCCESS);
} /* main */

This can be run against an Ext3 filesystem as well as against an XFS
filesystem.  If successful, it will show:

	[root@andromeda src]# ./t_access_root /tmp/xxx 0 4043 4043
	---------- 1 dhowells dhowells 0 2008-12-31 03:00 /tmp/xxx
	access(/tmp/xxx, 0) returns 0
	access(/tmp/xxx, R_OK) returns 0
	access(/tmp/xxx, W_OK) returns 0
	access(/tmp/xxx, X_OK) returns -1
	access(/tmp/xxx, R_OK | W_OK) returns 0
	access(/tmp/xxx, R_OK | X_OK) returns -1
	access(/tmp/xxx, W_OK | X_OK) returns -1
	access(/tmp/xxx, R_OK | W_OK | X_OK) returns -1

If unsuccessful, it will show:

	[root@andromeda src]# ./t_access_root /tmp/xxx 0 4043 4043
	---------- 1 dhowells dhowells 0 2008-12-31 02:56 /tmp/xxx
	access(/tmp/xxx, 0) returns 0
	access(/tmp/xxx, R_OK) returns -1
	access(/tmp/xxx, W_OK) returns -1
	access(/tmp/xxx, X_OK) returns -1
	access(/tmp/xxx, R_OK | W_OK) returns -1
	access(/tmp/xxx, R_OK | X_OK) returns -1
	access(/tmp/xxx, W_OK | X_OK) returns -1
	access(/tmp/xxx, R_OK | W_OK | X_OK) returns -1

I've also tested the fix with the SELinux and syscalls LTP testsuites.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-01-05 11:17:04 +11:00
Al Viro
5af75d8d58 audit: validate comparison operations, store them in sane form
Don't store the field->op in the messy (and very inconvenient for e.g.
audit_comparator()) form; translate to dense set of values and do full
validation of userland-submitted value while we are at it.

->audit_init_rule() and ->audit_match_rule() get new values now; in-tree
instances updated.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-01-04 15:14:42 -05:00
Casey Schaufler
6d3dc07cbb smack: Add support for unlabeled network hosts and networks
Add support for unlabeled network hosts and networks.
Relies heavily on Paul Moore's netlabel support.

Creates a new entry in /smack called netlabel. Writes to /smack/netlabel
take the form:

    A.B.C.D LABEL
or
    A.B.C.D/N LABEL

where A.B.C.D is a network address, N is an integer between 0-32,
and LABEL is the Smack label to be used. If /N is omitted /32 is
assumed. N designates the netmask for the address. Entries are
matched by the most specific address/mask pair. 0.0.0.0/0 will
match everything, while 192.168.1.117/32 will match exactly one
host.

A new system label "@", pronounced "web", is defined. Processes
can not be assigned the web label. An address assigned the web
label can be written to by any process, and packets coming from
a web address can be written to any socket. Use of the web label
is a violation of any strict MAC policy, but the web label has
been requested many times.

The nltype entry has been removed from /smack. It did not work right
and the netlabel interface can be used to specify that all hosts
be treated as unlabeled.

CIPSO labels on incoming packets will be honored, even from designated
single label hosts. Single label hosts can only be written to by
processes with labels that can write to the label of the host.
Packets sent to single label hosts will always be unlabeled.

Once added a single label designation cannot be removed, however
the label may be changed.

The behavior of the ambient label remains unchanged.


Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul.moore@hp.com>
2008-12-31 12:54:12 -05:00
Paul Moore
6c2e8ac095 netlabel: Update kernel configuration API
Update the NetLabel kernel API to expose the new features added in kernel
releases 2.6.25 and 2.6.28: the static/fallback label functionality and network
address based selectors.

Signed-off-by: Paul Moore <paul.moore@hp.com>
2008-12-31 12:54:11 -05:00
Sergio Luis
81ea714bf1 smackfs: check for allocation failures in smk_set_access()
smackfs: check for allocation failures in smk_set_access()

 While adding a new subject/object pair to smack_list, smk_set_access()
 didn't check the return of kzalloc().

 This patch changes smk_set_access() to return 0 or -ENOMEM, based on
 kzalloc()'s return. It also updates its caller, smk_write_load(), to
 check for smk_set_access()'s return, given it is no longer a void
 return function.

 Signed-off-by: Sergio Luis <sergio@larces.uece.br>
 To: Casey Schaufler <casey@schaufler-ca.com>
 Cc: Ahmed S. Darwish <darwish.07@gmail.com>
 Cc: LSM <linux-security-module@vger.kernel.org>
 Cc: LKLM <linux-kernel@vger.kernel.org>

Acked-by: Casey Schaufler <casey@schaufler-ca.com>
2008-12-25 12:14:55 +11:00
James Morris
12204e24b1 security: pass mount flags to security_sb_kern_mount()
Pass mount flags to security_sb_kern_mount(), so security modules
can determine if a mount operation is being performed by the kernel.

Signed-off-by: James Morris <jmorris@namei.org>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
2008-12-20 09:02:39 +11:00
David Howells
3a3b7ce933 CRED: Allow kernel services to override LSM settings for task actions
Allow kernel services to override LSM settings appropriate to the actions
performed by a task by duplicating a set of credentials, modifying it and then
using task_struct::cred to point to it when performing operations on behalf of
a task.

This is used, for example, by CacheFiles which has to transparently access the
cache on behalf of a process that thinks it is doing, say, NFS accesses with a
potentially inappropriate (with respect to accessing the cache) set of
credentials.

This patch provides two LSM hooks for modifying a task security record:

 (*) security_kernel_act_as() which allows modification of the security datum
     with which a task acts on other objects (most notably files).

 (*) security_kernel_create_files_as() which allows modification of the
     security datum that is used to initialise the security data on a file that
     a task creates.

The patch also provides four new credentials handling functions, which wrap the
LSM functions:

 (1) prepare_kernel_cred()

     Prepare a set of credentials for a kernel service to use, based either on
     a daemon's credentials or on init_cred.  All the keyrings are cleared.

 (2) set_security_override()

     Set the LSM security ID in a set of credentials to a specific security
     context, assuming permission from the LSM policy.

 (3) set_security_override_from_ctx()

     As (2), but takes the security context as a string.

 (4) set_create_files_as()

     Set the file creation LSM security ID in a set of credentials to be the
     same as that on a particular inode.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> [Smack changes]
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-14 10:39:28 +11:00
David Howells
a6f76f23d2 CRED: Make execve() take advantage of copy-on-write credentials
Make execve() take advantage of copy-on-write credentials, allowing it to set
up the credentials in advance, and then commit the whole lot after the point
of no return.

This patch and the preceding patches have been tested with the LTP SELinux
testsuite.

This patch makes several logical sets of alteration:

 (1) execve().

     The credential bits from struct linux_binprm are, for the most part,
     replaced with a single credentials pointer (bprm->cred).  This means that
     all the creds can be calculated in advance and then applied at the point
     of no return with no possibility of failure.

     I would like to replace bprm->cap_effective with:

	cap_isclear(bprm->cap_effective)

     but this seems impossible due to special behaviour for processes of pid 1
     (they always retain their parent's capability masks where normally they'd
     be changed - see cap_bprm_set_creds()).

     The following sequence of events now happens:

     (a) At the start of do_execve, the current task's cred_exec_mutex is
     	 locked to prevent PTRACE_ATTACH from obsoleting the calculation of
     	 creds that we make.

     (a) prepare_exec_creds() is then called to make a copy of the current
     	 task's credentials and prepare it.  This copy is then assigned to
     	 bprm->cred.

  	 This renders security_bprm_alloc() and security_bprm_free()
     	 unnecessary, and so they've been removed.

     (b) The determination of unsafe execution is now performed immediately
     	 after (a) rather than later on in the code.  The result is stored in
     	 bprm->unsafe for future reference.

     (c) prepare_binprm() is called, possibly multiple times.

     	 (i) This applies the result of set[ug]id binaries to the new creds
     	     attached to bprm->cred.  Personality bit clearance is recorded,
     	     but now deferred on the basis that the exec procedure may yet
     	     fail.

         (ii) This then calls the new security_bprm_set_creds().  This should
	     calculate the new LSM and capability credentials into *bprm->cred.

	     This folds together security_bprm_set() and parts of
	     security_bprm_apply_creds() (these two have been removed).
	     Anything that might fail must be done at this point.

         (iii) bprm->cred_prepared is set to 1.

	     bprm->cred_prepared is 0 on the first pass of the security
	     calculations, and 1 on all subsequent passes.  This allows SELinux
	     in (ii) to base its calculations only on the initial script and
	     not on the interpreter.

     (d) flush_old_exec() is called to commit the task to execution.  This
     	 performs the following steps with regard to credentials:

	 (i) Clear pdeath_signal and set dumpable on certain circumstances that
	     may not be covered by commit_creds().

         (ii) Clear any bits in current->personality that were deferred from
             (c.i).

     (e) install_exec_creds() [compute_creds() as was] is called to install the
     	 new credentials.  This performs the following steps with regard to
     	 credentials:

         (i) Calls security_bprm_committing_creds() to apply any security
             requirements, such as flushing unauthorised files in SELinux, that
             must be done before the credentials are changed.

	     This is made up of bits of security_bprm_apply_creds() and
	     security_bprm_post_apply_creds(), both of which have been removed.
	     This function is not allowed to fail; anything that might fail
	     must have been done in (c.ii).

         (ii) Calls commit_creds() to apply the new credentials in a single
             assignment (more or less).  Possibly pdeath_signal and dumpable
             should be part of struct creds.

	 (iii) Unlocks the task's cred_replace_mutex, thus allowing
	     PTRACE_ATTACH to take place.

         (iv) Clears The bprm->cred pointer as the credentials it was holding
             are now immutable.

         (v) Calls security_bprm_committed_creds() to apply any security
             alterations that must be done after the creds have been changed.
             SELinux uses this to flush signals and signal handlers.

     (f) If an error occurs before (d.i), bprm_free() will call abort_creds()
     	 to destroy the proposed new credentials and will then unlock
     	 cred_replace_mutex.  No changes to the credentials will have been
     	 made.

 (2) LSM interface.

     A number of functions have been changed, added or removed:

     (*) security_bprm_alloc(), ->bprm_alloc_security()
     (*) security_bprm_free(), ->bprm_free_security()

     	 Removed in favour of preparing new credentials and modifying those.

     (*) security_bprm_apply_creds(), ->bprm_apply_creds()
     (*) security_bprm_post_apply_creds(), ->bprm_post_apply_creds()

     	 Removed; split between security_bprm_set_creds(),
     	 security_bprm_committing_creds() and security_bprm_committed_creds().

     (*) security_bprm_set(), ->bprm_set_security()

     	 Removed; folded into security_bprm_set_creds().

     (*) security_bprm_set_creds(), ->bprm_set_creds()

     	 New.  The new credentials in bprm->creds should be checked and set up
     	 as appropriate.  bprm->cred_prepared is 0 on the first call, 1 on the
     	 second and subsequent calls.

     (*) security_bprm_committing_creds(), ->bprm_committing_creds()
     (*) security_bprm_committed_creds(), ->bprm_committed_creds()

     	 New.  Apply the security effects of the new credentials.  This
     	 includes closing unauthorised files in SELinux.  This function may not
     	 fail.  When the former is called, the creds haven't yet been applied
     	 to the process; when the latter is called, they have.

 	 The former may access bprm->cred, the latter may not.

 (3) SELinux.

     SELinux has a number of changes, in addition to those to support the LSM
     interface changes mentioned above:

     (a) The bprm_security_struct struct has been removed in favour of using
     	 the credentials-under-construction approach.

     (c) flush_unauthorized_files() now takes a cred pointer and passes it on
     	 to inode_has_perm(), file_has_perm() and dentry_open().

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-14 10:39:24 +11:00
David Howells
d84f4f992c CRED: Inaugurate COW credentials
Inaugurate copy-on-write credentials management.  This uses RCU to manage the
credentials pointer in the task_struct with respect to accesses by other tasks.
A process may only modify its own credentials, and so does not need locking to
access or modify its own credentials.

A mutex (cred_replace_mutex) is added to the task_struct to control the effect
of PTRACE_ATTACHED on credential calculations, particularly with respect to
execve().

With this patch, the contents of an active credentials struct may not be
changed directly; rather a new set of credentials must be prepared, modified
and committed using something like the following sequence of events:

	struct cred *new = prepare_creds();
	int ret = blah(new);
	if (ret < 0) {
		abort_creds(new);
		return ret;
	}
	return commit_creds(new);

There are some exceptions to this rule: the keyrings pointed to by the active
credentials may be instantiated - keyrings violate the COW rule as managing
COW keyrings is tricky, given that it is possible for a task to directly alter
the keys in a keyring in use by another task.

To help enforce this, various pointers to sets of credentials, such as those in
the task_struct, are declared const.  The purpose of this is compile-time
discouragement of altering credentials through those pointers.  Once a set of
credentials has been made public through one of these pointers, it may not be
modified, except under special circumstances:

  (1) Its reference count may incremented and decremented.

  (2) The keyrings to which it points may be modified, but not replaced.

The only safe way to modify anything else is to create a replacement and commit
using the functions described in Documentation/credentials.txt (which will be
added by a later patch).

This patch and the preceding patches have been tested with the LTP SELinux
testsuite.

This patch makes several logical sets of alteration:

 (1) execve().

     This now prepares and commits credentials in various places in the
     security code rather than altering the current creds directly.

 (2) Temporary credential overrides.

     do_coredump() and sys_faccessat() now prepare their own credentials and
     temporarily override the ones currently on the acting thread, whilst
     preventing interference from other threads by holding cred_replace_mutex
     on the thread being dumped.

     This will be replaced in a future patch by something that hands down the
     credentials directly to the functions being called, rather than altering
     the task's objective credentials.

 (3) LSM interface.

     A number of functions have been changed, added or removed:

     (*) security_capset_check(), ->capset_check()
     (*) security_capset_set(), ->capset_set()

     	 Removed in favour of security_capset().

     (*) security_capset(), ->capset()

     	 New.  This is passed a pointer to the new creds, a pointer to the old
     	 creds and the proposed capability sets.  It should fill in the new
     	 creds or return an error.  All pointers, barring the pointer to the
     	 new creds, are now const.

     (*) security_bprm_apply_creds(), ->bprm_apply_creds()

     	 Changed; now returns a value, which will cause the process to be
     	 killed if it's an error.

     (*) security_task_alloc(), ->task_alloc_security()

     	 Removed in favour of security_prepare_creds().

     (*) security_cred_free(), ->cred_free()

     	 New.  Free security data attached to cred->security.

     (*) security_prepare_creds(), ->cred_prepare()

     	 New. Duplicate any security data attached to cred->security.

     (*) security_commit_creds(), ->cred_commit()

     	 New. Apply any security effects for the upcoming installation of new
     	 security by commit_creds().

     (*) security_task_post_setuid(), ->task_post_setuid()

     	 Removed in favour of security_task_fix_setuid().

     (*) security_task_fix_setuid(), ->task_fix_setuid()

     	 Fix up the proposed new credentials for setuid().  This is used by
     	 cap_set_fix_setuid() to implicitly adjust capabilities in line with
     	 setuid() changes.  Changes are made to the new credentials, rather
     	 than the task itself as in security_task_post_setuid().

     (*) security_task_reparent_to_init(), ->task_reparent_to_init()

     	 Removed.  Instead the task being reparented to init is referred
     	 directly to init's credentials.

	 NOTE!  This results in the loss of some state: SELinux's osid no
	 longer records the sid of the thread that forked it.

     (*) security_key_alloc(), ->key_alloc()
     (*) security_key_permission(), ->key_permission()

     	 Changed.  These now take cred pointers rather than task pointers to
     	 refer to the security context.

 (4) sys_capset().

     This has been simplified and uses less locking.  The LSM functions it
     calls have been merged.

 (5) reparent_to_kthreadd().

     This gives the current thread the same credentials as init by simply using
     commit_thread() to point that way.

 (6) __sigqueue_alloc() and switch_uid()

     __sigqueue_alloc() can't stop the target task from changing its creds
     beneath it, so this function gets a reference to the currently applicable
     user_struct which it then passes into the sigqueue struct it returns if
     successful.

     switch_uid() is now called from commit_creds(), and possibly should be
     folded into that.  commit_creds() should take care of protecting
     __sigqueue_alloc().

 (7) [sg]et[ug]id() and co and [sg]et_current_groups.

     The set functions now all use prepare_creds(), commit_creds() and
     abort_creds() to build and check a new set of credentials before applying
     it.

     security_task_set[ug]id() is called inside the prepared section.  This
     guarantees that nothing else will affect the creds until we've finished.

     The calling of set_dumpable() has been moved into commit_creds().

     Much of the functionality of set_user() has been moved into
     commit_creds().

     The get functions all simply access the data directly.

 (8) security_task_prctl() and cap_task_prctl().

     security_task_prctl() has been modified to return -ENOSYS if it doesn't
     want to handle a function, or otherwise return the return value directly
     rather than through an argument.

     Additionally, cap_task_prctl() now prepares a new set of credentials, even
     if it doesn't end up using it.

 (9) Keyrings.

     A number of changes have been made to the keyrings code:

     (a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have
     	 all been dropped and built in to the credentials functions directly.
     	 They may want separating out again later.

     (b) key_alloc() and search_process_keyrings() now take a cred pointer
     	 rather than a task pointer to specify the security context.

     (c) copy_creds() gives a new thread within the same thread group a new
     	 thread keyring if its parent had one, otherwise it discards the thread
     	 keyring.

     (d) The authorisation key now points directly to the credentials to extend
     	 the search into rather pointing to the task that carries them.

     (e) Installing thread, process or session keyrings causes a new set of
     	 credentials to be created, even though it's not strictly necessary for
     	 process or session keyrings (they're shared).

(10) Usermode helper.

     The usermode helper code now carries a cred struct pointer in its
     subprocess_info struct instead of a new session keyring pointer.  This set
     of credentials is derived from init_cred and installed on the new process
     after it has been cloned.

     call_usermodehelper_setup() allocates the new credentials and
     call_usermodehelper_freeinfo() discards them if they haven't been used.  A
     special cred function (prepare_usermodeinfo_creds()) is provided
     specifically for call_usermodehelper_setup() to call.

     call_usermodehelper_setkeys() adjusts the credentials to sport the
     supplied keyring as the new session keyring.

(11) SELinux.

     SELinux has a number of changes, in addition to those to support the LSM
     interface changes mentioned above:

     (a) selinux_setprocattr() no longer does its check for whether the
     	 current ptracer can access processes with the new SID inside the lock
     	 that covers getting the ptracer's SID.  Whilst this lock ensures that
     	 the check is done with the ptracer pinned, the result is only valid
     	 until the lock is released, so there's no point doing it inside the
     	 lock.

(12) is_single_threaded().

     This function has been extracted from selinux_setprocattr() and put into
     a file of its own in the lib/ directory as join_session_keyring() now
     wants to use it too.

     The code in SELinux just checked to see whether a task shared mm_structs
     with other tasks (CLONE_VM), but that isn't good enough.  We really want
     to know if they're part of the same thread group (CLONE_THREAD).

(13) nfsd.

     The NFS server daemon now has to use the COW credentials to set the
     credentials it is going to use.  It really needs to pass the credentials
     down to the functions it calls, but it can't do that until other patches
     in this series have been applied.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-14 10:39:23 +11:00
David Howells
c69e8d9c01 CRED: Use RCU to access another task's creds and to release a task's own creds
Use RCU to access another task's creds and to release a task's own creds.
This means that it will be possible for the credentials of a task to be
replaced without another task (a) requiring a full lock to read them, and (b)
seeing deallocated memory.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-14 10:39:19 +11:00
David Howells
86a264abe5 CRED: Wrap current->cred and a few other accessors
Wrap current->cred and a few other accessors to hide their actual
implementation.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-14 10:39:18 +11:00
David Howells
f1752eec61 CRED: Detach the credentials from task_struct
Detach the credentials from task_struct, duplicating them in copy_process()
and releasing them in __put_task_struct().

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-14 10:39:17 +11:00
David Howells
b6dff3ec5e CRED: Separate task security context from task_struct
Separate the task security context from task_struct.  At this point, the
security data is temporarily embedded in the task_struct with two pointers
pointing to it.

Note that the Alpha arch is altered as it refers to (E)UID and (E)GID in
entry.S via asm-offsets.

With comment fixes Signed-off-by: Marc Dionne <marc.c.dionne@gmail.com>

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-14 10:39:16 +11:00
James Morris
0da939b005 Merge branch 'master' of git://git.infradead.org/users/pcmoore/lblnet-2.6_next into next 2008-10-11 09:26:14 +11:00
Paul Moore
b1edeb1023 netlabel: Replace protocol/NetLabel linking with refrerence counts
NetLabel has always had a list of backpointers in the CIPSO DOI definition
structure which pointed to the NetLabel LSM domain mapping structures which
referenced the CIPSO DOI struct.  The rationale for this was that when an
administrator removed a CIPSO DOI from the system all of the associated
NetLabel LSM domain mappings should be removed as well; a list of
backpointers made this a simple operation.

Unfortunately, while the backpointers did make the removal easier they were
a bit of a mess from an implementation point of view which was making
further development difficult.  Since the removal of a CIPSO DOI is a
realtively rare event it seems to make sense to remove this backpointer
list as the optimization was hurting us more then it was helping.  However,
we still need to be able to track when a CIPSO DOI definition is being used
so replace the backpointer list with a reference count.  In order to
preserve the current functionality of removing the associated LSM domain
mappings when a CIPSO DOI is removed we walk the LSM domain mapping table,
removing the relevant entries.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Reviewed-by: James Morris <jmorris@namei.org>
2008-10-10 10:16:31 -04:00
Paul Moore
a8134296ba smack: Fix missing calls to netlbl_skbuff_err()
Smack needs to call netlbl_skbuff_err() to let NetLabel do the necessary
protocol specific error handling.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
2008-10-10 10:16:31 -04:00
James Morris
86d688984d Merge branch 'master' into next 2008-08-28 10:47:34 +10:00
David Howells
5cd9c58fbe security: Fix setting of PF_SUPERPRIV by __capable()
Fix the setting of PF_SUPERPRIV by __capable() as it could corrupt the flags
the target process if that is not the current process and it is trying to
change its own flags in a different way at the same time.

__capable() is using neither atomic ops nor locking to protect t->flags.  This
patch removes __capable() and introduces has_capability() that doesn't set
PF_SUPERPRIV on the process being queried.

This patch further splits security_ptrace() in two:

 (1) security_ptrace_may_access().  This passes judgement on whether one
     process may access another only (PTRACE_MODE_ATTACH for ptrace() and
     PTRACE_MODE_READ for /proc), and takes a pointer to the child process.
     current is the parent.

 (2) security_ptrace_traceme().  This passes judgement on PTRACE_TRACEME only,
     and takes only a pointer to the parent process.  current is the child.

     In Smack and commoncap, this uses has_capability() to determine whether
     the parent will be permitted to use PTRACE_ATTACH if normal checks fail.
     This does not set PF_SUPERPRIV.

Two of the instances of __capable() actually only act on current, and so have
been changed to calls to capable().

Of the places that were using __capable():

 (1) The OOM killer calls __capable() thrice when weighing the killability of a
     process.  All of these now use has_capability().

 (2) cap_ptrace() and smack_ptrace() were using __capable() to check to see
     whether the parent was allowed to trace any process.  As mentioned above,
     these have been split.  For PTRACE_ATTACH and /proc, capable() is now
     used, and for PTRACE_TRACEME, has_capability() is used.

 (3) cap_safe_nice() only ever saw current, so now uses capable().

 (4) smack_setprocattr() rejected accesses to tasks other than current just
     after calling __capable(), so the order of these two tests have been
     switched and capable() is used instead.

 (5) In smack_file_send_sigiotask(), we need to allow privileged processes to
     receive SIGIO on files they're manipulating.

 (6) In smack_task_wait(), we let a process wait for a privileged process,
     whether or not the process doing the waiting is privileged.

I've tested this with the LTP SELinux and syscalls testscripts.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Andrew G. Morgan <morgan@kernel.org>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: James Morris <jmorris@namei.org>
2008-08-14 22:59:43 +10:00
Casey Schaufler
1544623536 smack: limit privilege by label
There have been a number of requests to make the Smack LSM
enforce MAC even in the face of privilege, either capability
based or superuser based. This is not universally desired,
however, so it seems desirable to make it optional. Further,
at least one legacy OS implemented a scheme whereby only
processes running with one particular label could be exempt
from MAC. This patch supports these three cases.

If /smack/onlycap is empty (unset or null-string) privilege
is enforced in the normal way.

If /smack/onlycap contains a label only processes running with
that label may be MAC exempt.

If the label in /smack/onlycap is the star label ("*") the
semantics of the star label combine with the privilege
restrictions to prevent any violations of MAC, even in the
presence of privilege.

Again, this will be independent of the privilege scheme.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: James Morris <jmorris@namei.org>
2008-08-05 10:55:53 +10:00
Al Viro
b77b0646ef [PATCH] pass MAY_OPEN to vfs_permission() explicitly
... and get rid of the last "let's deduce mask from nameidata->flags"
bit.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2008-07-26 20:53:22 -04:00
James Morris
6f0f0fd496 security: remove register_security hook
The register security hook is no longer required, as the capability
module is always registered.  LSMs wishing to stack capability as
a secondary module should do so explicitly.

Signed-off-by: James Morris <jmorris@namei.org>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-07-14 15:04:06 +10:00
Stephen Smalley
006ebb40d3 Security: split proc ptrace checking into read vs. attach
Enable security modules to distinguish reading of process state via
proc from full ptrace access by renaming ptrace_may_attach to
ptrace_may_access and adding a mode argument indicating whether only
read access or full attach access is requested.  This allows security
modules to permit access to reading process state without granting
full ptrace access.  The base DAC/capability checking remains unchanged.

Read access to /proc/pid/mem continues to apply a full ptrace attach
check since check_mem_permission() already requires the current task
to already be ptracing the target.  The other ptrace checks within
proc for elements like environ, maps, and fds are changed to pass the
read mode instead of attach.

In the SELinux case, we model such reading of process state as a
reading of a proc file labeled with the target process' label.  This
enables SELinux policy to permit such reading of process state without
permitting control or manipulation of the target process, as there are
a number of cases where programs probe for such information via proc
but do not need to be able to control the target (e.g. procps,
lsof, PolicyKit, ConsoleKit).  At present we have to choose between
allowing full ptrace in policy (more permissive than required/desired)
or breaking functionality (or in some cases just silencing the denials
via dontaudit rules but this can hide genuine attacks).

This version of the patch incorporates comments from Casey Schaufler
(change/replace existing ptrace_may_attach interface, pass access
mode), and Chris Wright (provide greater consistency in the checking).

Note that like their predecessors __ptrace_may_attach and
ptrace_may_attach, the __ptrace_may_access and ptrace_may_access
interfaces use different return value conventions from each other (0
or -errno vs. 1 or 0).  I retained this difference to avoid any
changes to the caller logic but made the difference clearer by
changing the latter interface to return a bool rather than an int and
by adding a comment about it to ptrace.h for any future callers.

Signed-off-by:  Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: James Morris <jmorris@namei.org>
2008-07-14 15:01:47 +10:00
Casey Schaufler
e97dcb0ead Smack: fuse mount hang fix
The d_instantiate hook for Smack can hang on the root inode of a
filesystem if the file system code has not really done all the set-up.
Fuse is known to encounter this problem.

This change detects an attempt to instantiate a root inode and addresses
it early in the processing, before any attempt is made to do something
that might hang.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Tested-by: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-06-04 08:50:43 -07:00