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Smack: Simplified Mandatory Access Control Kernel

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Smack is the Simplified Mandatory Access Control Kernel.

Smack implements mandatory access control (MAC) using labels
attached to tasks and data containers, including files, SVIPC,
and other tasks. Smack is a kernel based scheme that requires
an absolute minimum of application support and a very small
amount of configuration data.

Smack uses extended attributes and
provides a set of general mount options, borrowing technics used
elsewhere. Smack uses netlabel for CIPSO labeling. Smack provides
a pseudo-filesystem smackfs that is used for manipulation of
system Smack attributes.

The patch, patches for ls and sshd, a README, a startup script,
and x86 binaries for ls and sshd are also available on

    http://www.schaufler-ca.com

Development has been done using Fedora Core 7 in a virtual machine
environment and on an old Sony laptop.

Smack provides mandatory access controls based on the label attached
to a task and the label attached to the object it is attempting to
access. Smack labels are deliberately short (1-23 characters) text
strings. Single character labels using special characters are reserved
for system use. The only operation applied to Smack labels is equality
comparison. No wildcards or expressions, regular or otherwise, are
used. Smack labels are composed of printable characters and may not
include "/".

A file always gets the Smack label of the task that created it.

Smack defines and uses these labels:

    "*" - pronounced "star"
    "_" - pronounced "floor"
    "^" - pronounced "hat"
    "?" - pronounced "huh"

The access rules enforced by Smack are, in order:

1. Any access requested by a task labeled "*" is denied.
2. A read or execute access requested by a task labeled "^"
   is permitted.
3. A read or execute access requested on an object labeled "_"
   is permitted.
4. Any access requested on an object labeled "*" is permitted.
5. Any access requested by a task on an object with the same
   label is permitted.
6. Any access requested that is explicitly defined in the loaded
   rule set is permitted.
7. Any other access is denied.

Rules may be explicitly defined by writing subject,object,access
triples to /smack/load.

Smack rule sets can be easily defined that describe Bell&LaPadula
sensitivity, Biba integrity, and a variety of interesting
configurations. Smack rule sets can be modified on the fly to
accommodate changes in the operating environment or even the time
of day.

Some practical use cases:

Hierarchical levels. The less common of the two usual uses
for MLS systems is to define hierarchical levels, often
unclassified, confidential, secret, and so on. To set up smack
to support this, these rules could be defined:

   C        Unclass rx
   S        C       rx
   S        Unclass rx
   TS       S       rx
   TS       C       rx
   TS       Unclass rx

A TS process can read S, C, and Unclass data, but cannot write it.
An S process can read C and Unclass. Note that specifying that
TS can read S and S can read C does not imply TS can read C, it
has to be explicitly stated.

Non-hierarchical categories. This is the more common of the
usual uses for an MLS system. Since the default rule is that a
subject cannot access an object with a different label no
access rules are required to implement compartmentalization.

A case that the Bell & LaPadula policy does not allow is demonstrated
with this Smack access rule:

A case that Bell&LaPadula does not allow that Smack does:

    ESPN    ABC   r
    ABC     ESPN  r

On my portable video device I have two applications, one that
shows ABC programming and the other ESPN programming. ESPN wants
to show me sport stories that show up as news, and ABC will
only provide minimal information about a sports story if ESPN
is covering it. Each side can look at the other's info, neither
can change the other. Neither can see what FOX is up to, which
is just as well all things considered.

Another case that I especially like:

    SatData Guard   w
    Guard   Publish w

A program running with the Guard label opens a UDP socket and
accepts messages sent by a program running with a SatData label.
The Guard program inspects the message to ensure it is wholesome
and if it is sends it to a program running with the Publish label.
This program then puts the information passed in an appropriate
place. Note that the Guard program cannot write to a Publish
file system object because file system semanitic require read as
well as write.

The four cases (categories, levels, mutual read, guardbox) here
are all quite real, and problems I've been asked to solve over
the years. The first two are easy to do with traditonal MLS systems
while the last two you can't without invoking privilege, at least
for a while.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Cc: Joshua Brindle <method@manicmethod.com>
Cc: Paul Moore <paul.moore@hp.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: James Morris <jmorris@namei.org>
Cc: "Ahmed S. Darwish" <darwish.07@gmail.com>
Cc: Andrew G. Morgan <morgan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Casey Schaufler 2008-02-04 22:29:50 -08:00 committed by Linus Torvalds
parent eda61d32e8
commit e114e47377
10 changed files with 4611 additions and 3 deletions
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493
Documentation/Smack.txt Normal file
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@ -0,0 +1,493 @@
"Good for you, you've decided to clean the elevator!"
- The Elevator, from Dark Star
Smack is the the Simplified Mandatory Access Control Kernel.
Smack is a kernel based implementation of mandatory access
control that includes simplicity in its primary design goals.
Smack is not the only Mandatory Access Control scheme
available for Linux. Those new to Mandatory Access Control
are encouraged to compare Smack with the other mechanisms
available to determine which is best suited to the problem
at hand.
Smack consists of three major components:
- The kernel
- A start-up script and a few modified applications
- Configuration data
The kernel component of Smack is implemented as a Linux
Security Modules (LSM) module. It requires netlabel and
works best with file systems that support extended attributes,
although xattr support is not strictly required.
It is safe to run a Smack kernel under a "vanilla" distribution.
Smack kernels use the CIPSO IP option. Some network
configurations are intolerant of IP options and can impede
access to systems that use them as Smack does.
The startup script etc-init.d-smack should be installed
in /etc/init.d/smack and should be invoked early in the
start-up process. On Fedora rc5.d/S02smack is recommended.
This script ensures that certain devices have the correct
Smack attributes and loads the Smack configuration if
any is defined. This script invokes two programs that
ensure configuration data is properly formatted. These
programs are /usr/sbin/smackload and /usr/sin/smackcipso.
The system will run just fine without these programs,
but it will be difficult to set access rules properly.
A version of "ls" that provides a "-M" option to display
Smack labels on long listing is available.
A hacked version of sshd that allows network logins by users
with specific Smack labels is available. This version does
not work for scp. You must set the /etc/ssh/sshd_config
line:
UsePrivilegeSeparation no
The format of /etc/smack/usr is:
username smack
In keeping with the intent of Smack, configuration data is
minimal and not strictly required. The most important
configuration step is mounting the smackfs pseudo filesystem.
Add this line to /etc/fstab:
smackfs /smack smackfs smackfsdef=* 0 0
and create the /smack directory for mounting.
Smack uses extended attributes (xattrs) to store file labels.
The command to set a Smack label on a file is:
# attr -S -s SMACK64 -V "value" path
NOTE: Smack labels are limited to 23 characters. The attr command
does not enforce this restriction and can be used to set
invalid Smack labels on files.
If you don't do anything special all users will get the floor ("_")
label when they log in. If you do want to log in via the hacked ssh
at other labels use the attr command to set the smack value on the
home directory and it's contents.
You can add access rules in /etc/smack/accesses. They take the form:
subjectlabel objectlabel access
access is a combination of the letters rwxa which specify the
kind of access permitted a subject with subjectlabel on an
object with objectlabel. If there is no rule no access is allowed.
A process can see the smack label it is running with by
reading /proc/self/attr/current. A privileged process can
set the process smack by writing there.
Look for additional programs on http://schaufler-ca.com
From the Smack Whitepaper:
The Simplified Mandatory Access Control Kernel
Casey Schaufler
casey@schaufler-ca.com
Mandatory Access Control
Computer systems employ a variety of schemes to constrain how information is
shared among the people and services using the machine. Some of these schemes
allow the program or user to decide what other programs or users are allowed
access to pieces of data. These schemes are called discretionary access
control mechanisms because the access control is specified at the discretion
of the user. Other schemes do not leave the decision regarding what a user or
program can access up to users or programs. These schemes are called mandatory
access control mechanisms because you don't have a choice regarding the users
or programs that have access to pieces of data.
Bell & LaPadula
From the middle of the 1980's until the turn of the century Mandatory Access
Control (MAC) was very closely associated with the Bell & LaPadula security
model, a mathematical description of the United States Department of Defense
policy for marking paper documents. MAC in this form enjoyed a following
within the Capital Beltway and Scandinavian supercomputer centers but was
often sited as failing to address general needs.
Domain Type Enforcement
Around the turn of the century Domain Type Enforcement (DTE) became popular.
This scheme organizes users, programs, and data into domains that are
protected from each other. This scheme has been widely deployed as a component
of popular Linux distributions. The administrative overhead required to
maintain this scheme and the detailed understanding of the whole system
necessary to provide a secure domain mapping leads to the scheme being
disabled or used in limited ways in the majority of cases.
Smack
Smack is a Mandatory Access Control mechanism designed to provide useful MAC
while avoiding the pitfalls of its predecessors. The limitations of Bell &
LaPadula are addressed by providing a scheme whereby access can be controlled
according to the requirements of the system and its purpose rather than those
imposed by an arcane government policy. The complexity of Domain Type
Enforcement and avoided by defining access controls in terms of the access
modes already in use.
Smack Terminology
The jargon used to talk about Smack will be familiar to those who have dealt
with other MAC systems and shouldn't be too difficult for the uninitiated to
pick up. There are four terms that are used in a specific way and that are
especially important:
Subject: A subject is an active entity on the computer system.
On Smack a subject is a task, which is in turn the basic unit
of execution.
Object: An object is a passive entity on the computer system.
On Smack files of all types, IPC, and tasks can be objects.
Access: Any attempt by a subject to put information into or get
information from an object is an access.
Label: Data that identifies the Mandatory Access Control
characteristics of a subject or an object.
These definitions are consistent with the traditional use in the security
community. There are also some terms from Linux that are likely to crop up:
Capability: A task that possesses a capability has permission to
violate an aspect of the system security policy, as identified by
the specific capability. A task that possesses one or more
capabilities is a privileged task, whereas a task with no
capabilities is an unprivileged task.
Privilege: A task that is allowed to violate the system security
policy is said to have privilege. As of this writing a task can
have privilege either by possessing capabilities or by having an
effective user of root.
Smack Basics
Smack is an extension to a Linux system. It enforces additional restrictions
on what subjects can access which objects, based on the labels attached to
each of the subject and the object.
Labels
Smack labels are ASCII character strings, one to twenty-three characters in
length. Single character labels using special characters, that being anything
other than a letter or digit, are reserved for use by the Smack development
team. Smack labels are unstructured, case sensitive, and the only operation
ever performed on them is comparison for equality. Smack labels cannot
contain unprintable characters or the "/" (slash) character.
There are some predefined labels:
_ Pronounced "floor", a single underscore character.
^ Pronounced "hat", a single circumflex character.
* Pronounced "star", a single asterisk character.
? Pronounced "huh", a single question mark character.
Every task on a Smack system is assigned a label. System tasks, such as
init(8) and systems daemons, are run with the floor ("_") label. User tasks
are assigned labels according to the specification found in the
/etc/smack/user configuration file.
Access Rules
Smack uses the traditional access modes of Linux. These modes are read,
execute, write, and occasionally append. There are a few cases where the
access mode may not be obvious. These include:
Signals: A signal is a write operation from the subject task to
the object task.
Internet Domain IPC: Transmission of a packet is considered a
write operation from the source task to the destination task.
Smack restricts access based on the label attached to a subject and the label
attached to the object it is trying to access. The rules enforced are, in
order:
1. Any access requested by a task labeled "*" is denied.
2. A read or execute access requested by a task labeled "^"
is permitted.
3. A read or execute access requested on an object labeled "_"
is permitted.
4. Any access requested on an object labeled "*" is permitted.
5. Any access requested by a task on an object with the same
label is permitted.
6. Any access requested that is explicitly defined in the loaded
rule set is permitted.
7. Any other access is denied.
Smack Access Rules
With the isolation provided by Smack access separation is simple. There are
many interesting cases where limited access by subjects to objects with
different labels is desired. One example is the familiar spy model of
sensitivity, where a scientist working on a highly classified project would be
able to read documents of lower classifications and anything she writes will
be "born" highly classified. To accommodate such schemes Smack includes a
mechanism for specifying rules allowing access between labels.
Access Rule Format
The format of an access rule is:
subject-label object-label access
Where subject-label is the Smack label of the task, object-label is the Smack
label of the thing being accessed, and access is a string specifying the sort
of access allowed. The Smack labels are limited to 23 characters. The access
specification is searched for letters that describe access modes:
a: indicates that append access should be granted.
r: indicates that read access should be granted.
w: indicates that write access should be granted.
x: indicates that execute access should be granted.
Uppercase values for the specification letters are allowed as well.
Access mode specifications can be in any order. Examples of acceptable rules
are:
TopSecret Secret rx
Secret Unclass R
Manager Game x
User HR w
New Old rRrRr
Closed Off -
Examples of unacceptable rules are:
Top Secret Secret rx
Ace Ace r
Odd spells waxbeans
Spaces are not allowed in labels. Since a subject always has access to files
with the same label specifying a rule for that case is pointless. Only
valid letters (rwxaRWXA) and the dash ('-') character are allowed in
access specifications. The dash is a placeholder, so "a-r" is the same
as "ar". A lone dash is used to specify that no access should be allowed.
Applying Access Rules
The developers of Linux rarely define new sorts of things, usually importing
schemes and concepts from other systems. Most often, the other systems are
variants of Unix. Unix has many endearing properties, but consistency of
access control models is not one of them. Smack strives to treat accesses as
uniformly as is sensible while keeping with the spirit of the underlying
mechanism.
File system objects including files, directories, named pipes, symbolic links,
and devices require access permissions that closely match those used by mode
bit access. To open a file for reading read access is required on the file. To
search a directory requires execute access. Creating a file with write access
requires both read and write access on the containing directory. Deleting a
file requires read and write access to the file and to the containing
directory. It is possible that a user may be able to see that a file exists
but not any of its attributes by the circumstance of having read access to the
containing directory but not to the differently labeled file. This is an
artifact of the file name being data in the directory, not a part of the file.
IPC objects, message queues, semaphore sets, and memory segments exist in flat
namespaces and access requests are only required to match the object in
question.
Process objects reflect tasks on the system and the Smack label used to access
them is the same Smack label that the task would use for its own access
attempts. Sending a signal via the kill() system call is a write operation
from the signaler to the recipient. Debugging a process requires both reading
and writing. Creating a new task is an internal operation that results in two
tasks with identical Smack labels and requires no access checks.
Sockets are data structures attached to processes and sending a packet from
one process to another requires that the sender have write access to the
receiver. The receiver is not required to have read access to the sender.
Setting Access Rules
The configuration file /etc/smack/accesses contains the rules to be set at
system startup. The contents are written to the special file /smack/load.
Rules can be written to /smack/load at any time and take effect immediately.
For any pair of subject and object labels there can be only one rule, with the
most recently specified overriding any earlier specification.
The program smackload is provided to ensure data is formatted
properly when written to /smack/load. This program reads lines
of the form
subjectlabel objectlabel mode.
Task Attribute
The Smack label of a process can be read from /proc/<pid>/attr/current. A
process can read its own Smack label from /proc/self/attr/current. A
privileged process can change its own Smack label by writing to
/proc/self/attr/current but not the label of another process.
File Attribute
The Smack label of a filesystem object is stored as an extended attribute
named SMACK64 on the file. This attribute is in the security namespace. It can
only be changed by a process with privilege.
Privilege
A process with CAP_MAC_OVERRIDE is privileged.
Smack Networking
As mentioned before, Smack enforces access control on network protocol
transmissions. Every packet sent by a Smack process is tagged with its Smack
label. This is done by adding a CIPSO tag to the header of the IP packet. Each
packet received is expected to have a CIPSO tag that identifies the label and
if it lacks such a tag the network ambient label is assumed. Before the packet
is delivered a check is made to determine that a subject with the label on the
packet has write access to the receiving process and if that is not the case
the packet is dropped.
CIPSO Configuration
It is normally unnecessary to specify the CIPSO configuration. The default
values used by the system handle all internal cases. Smack will compose CIPSO
label values to match the Smack labels being used without administrative
intervention. Unlabeled packets that come into the system will be given the
ambient label.
Smack requires configuration in the case where packets from a system that is
not smack that speaks CIPSO may be encountered. Usually this will be a Trusted
Solaris system, but there are other, less widely deployed systems out there.
CIPSO provides 3 important values, a Domain Of Interpretation (DOI), a level,
and a category set with each packet. The DOI is intended to identify a group
of systems that use compatible labeling schemes, and the DOI specified on the
smack system must match that of the remote system or packets will be
discarded. The DOI is 3 by default. The value can be read from /smack/doi and
can be changed by writing to /smack/doi.
The label and category set are mapped to a Smack label as defined in
/etc/smack/cipso.
A Smack/CIPSO mapping has the form:
smack level [category [category]*]
Smack does not expect the level or category sets to be related in any
particular way and does not assume or assign accesses based on them. Some
examples of mappings:
TopSecret 7
TS:A,B 7 1 2
SecBDE 5 2 4 6
RAFTERS 7 12 26
The ":" and "," characters are permitted in a Smack label but have no special
meaning.
The mapping of Smack labels to CIPSO values is defined by writing to
/smack/cipso. Again, the format of data written to this special file
is highly restrictive, so the program smackcipso is provided to
ensure the writes are done properly. This program takes mappings
on the standard input and sends them to /smack/cipso properly.
In addition to explicit mappings Smack supports direct CIPSO mappings. One
CIPSO level is used to indicate that the category set passed in the packet is
in fact an encoding of the Smack label. The level used is 250 by default. The
value can be read from /smack/direct and changed by writing to /smack/direct.
Socket Attributes
There are two attributes that are associated with sockets. These attributes
can only be set by privileged tasks, but any task can read them for their own
sockets.
SMACK64IPIN: The Smack label of the task object. A privileged
program that will enforce policy may set this to the star label.
SMACK64IPOUT: The Smack label transmitted with outgoing packets.
A privileged program may set this to match the label of another
task with which it hopes to communicate.
Writing Applications for Smack
There are three sorts of applications that will run on a Smack system. How an
application interacts with Smack will determine what it will have to do to
work properly under Smack.
Smack Ignorant Applications
By far the majority of applications have no reason whatever to care about the
unique properties of Smack. Since invoking a program has no impact on the
Smack label associated with the process the only concern likely to arise is
whether the process has execute access to the program.
Smack Relevant Applications
Some programs can be improved by teaching them about Smack, but do not make
any security decisions themselves. The utility ls(1) is one example of such a
program.
Smack Enforcing Applications
These are special programs that not only know about Smack, but participate in
the enforcement of system policy. In most cases these are the programs that
set up user sessions. There are also network services that provide information
to processes running with various labels.
File System Interfaces
Smack maintains labels on file system objects using extended attributes. The
Smack label of a file, directory, or other file system object can be obtained
using getxattr(2).
len = getxattr("/", "security.SMACK64", value, sizeof (value));
will put the Smack label of the root directory into value. A privileged
process can set the Smack label of a file system object with setxattr(2).
len = strlen("Rubble");
rc = setxattr("/foo", "security.SMACK64", "Rubble", len, 0);
will set the Smack label of /foo to "Rubble" if the program has appropriate
privilege.
Socket Interfaces
The socket attributes can be read using fgetxattr(2).
A privileged process can set the Smack label of outgoing packets with
fsetxattr(2).
len = strlen("Rubble");
rc = fsetxattr(fd, "security.SMACK64IPOUT", "Rubble", len, 0);
will set the Smack label "Rubble" on packets going out from the socket if the
program has appropriate privilege.
rc = fsetxattr(fd, "security.SMACK64IPIN, "*", strlen("*"), 0);
will set the Smack label "*" as the object label against which incoming
packets will be checked if the program has appropriate privilege.
Administration
Smack supports some mount options:
smackfsdef=label: specifies the label to give files that lack
the Smack label extended attribute.
smackfsroot=label: specifies the label to assign the root of the
file system if it lacks the Smack extended attribute.
smackfshat=label: specifies a label that must have read access to
all labels set on the filesystem. Not yet enforced.
smackfsfloor=label: specifies a label to which all labels set on the
filesystem must have read access. Not yet enforced.
These mount options apply to all file system types.

26
include/linux/capability.h
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@ -315,7 +315,24 @@ typedef struct kernel_cap_struct {
#define CAP_SETFCAP 31
#define CAP_LAST_CAP CAP_SETFCAP
/* Override MAC access.
The base kernel enforces no MAC policy.
An LSM may enforce a MAC policy, and if it does and it chooses
to implement capability based overrides of that policy, this is
the capability it should use to do so. */
#define CAP_MAC_OVERRIDE 32
/* Allow MAC configuration or state changes.
The base kernel requires no MAC configuration.
An LSM may enforce a MAC policy, and if it does and it chooses
to implement capability based checks on modifications to that
policy or the data required to maintain it, this is the
capability it should use to do so. */
#define CAP_MAC_ADMIN 33
#define CAP_LAST_CAP CAP_MAC_ADMIN
#define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)
@ -341,6 +358,8 @@ typedef struct kernel_cap_struct {
| CAP_TO_MASK(CAP_FOWNER) \
| CAP_TO_MASK(CAP_FSETID))
# define CAP_FS_MASK_B1 (CAP_TO_MASK(CAP_MAC_OVERRIDE))
#if _LINUX_CAPABILITY_U32S != 2
# error Fix up hand-coded capability macro initializers
#else /* HAND-CODED capability initializers */
@ -348,8 +367,9 @@ typedef struct kernel_cap_struct {
# define CAP_EMPTY_SET {{ 0, 0 }}
# define CAP_FULL_SET {{ ~0, ~0 }}
# define CAP_INIT_EFF_SET {{ ~CAP_TO_MASK(CAP_SETPCAP), ~0 }}
# define CAP_FS_SET {{ CAP_FS_MASK_B0, 0 }}
# define CAP_NFSD_SET {{ CAP_FS_MASK_B0|CAP_TO_MASK(CAP_SYS_RESOURCE), 0 }}
# define CAP_FS_SET {{ CAP_FS_MASK_B0, CAP_FS_MASK_B1 } }
# define CAP_NFSD_SET {{ CAP_FS_MASK_B0|CAP_TO_MASK(CAP_SYS_RESOURCE), \
CAP_FS_MASK_B1 } }
#endif /* _LINUX_CAPABILITY_U32S != 2 */

1
security/Kconfig
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@ -105,6 +105,7 @@ config SECURITY_ROOTPLUG
If you are unsure how to answer this question, answer N.
source security/selinux/Kconfig
source security/smack/Kconfig
endmenu

2
security/Makefile
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@ -4,6 +4,7 @@
obj-$(CONFIG_KEYS) += keys/
subdir-$(CONFIG_SECURITY_SELINUX) += selinux
subdir-$(CONFIG_SECURITY_SMACK) += smack
# if we don't select a security model, use the default capabilities
ifneq ($(CONFIG_SECURITY),y)
@ -14,5 +15,6 @@ endif
obj-$(CONFIG_SECURITY) += security.o dummy.o inode.o
# Must precede capability.o in order to stack properly.
obj-$(CONFIG_SECURITY_SELINUX) += selinux/built-in.o
obj-$(CONFIG_SECURITY_SMACK) += commoncap.o smack/built-in.o
obj-$(CONFIG_SECURITY_CAPABILITIES) += commoncap.o capability.o
obj-$(CONFIG_SECURITY_ROOTPLUG) += commoncap.o root_plug.o

10
security/smack/Kconfig Normal file
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@ -0,0 +1,10 @@
config SECURITY_SMACK
bool "Simplified Mandatory Access Control Kernel Support"
depends on NETLABEL && SECURITY_NETWORK
default n
help
This selects the Simplified Mandatory Access Control Kernel.
Smack is useful for sensitivity, integrity, and a variety
of other mandatory security schemes.
If you are unsure how to answer this question, answer N.

7
security/smack/Makefile Normal file
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@ -0,0 +1,7 @@
#
# Makefile for the SMACK LSM
#
obj-$(CONFIG_SECURITY_SMACK) := smack.o
smack-y := smack_lsm.o smack_access.o smackfs.o

220
security/smack/smack.h Normal file
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@ -0,0 +1,220 @@
/*
* Copyright (C) 2007 Casey Schaufler <casey@schaufler-ca.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, version 2.
*
* Author:
* Casey Schaufler <casey@schaufler-ca.com>
*
*/
#ifndef _SECURITY_SMACK_H
#define _SECURITY_SMACK_H
#include <linux/capability.h>
#include <linux/spinlock.h>
#include <net/netlabel.h>
/*
* Why 23? CIPSO is constrained to 30, so a 32 byte buffer is
* bigger than can be used, and 24 is the next lower multiple
* of 8, and there are too many issues if there isn't space set
* aside for the terminating null byte.
*/
#define SMK_MAXLEN 23
#define SMK_LABELLEN (SMK_MAXLEN+1)
/*
* How many kinds of access are there?
* Here's your answer.
*/
#define SMK_ACCESSDASH '-'
#define SMK_ACCESSLOW "rwxa"
#define SMK_ACCESSKINDS (sizeof(SMK_ACCESSLOW) - 1)
struct superblock_smack {
char *smk_root;
char *smk_floor;
char *smk_hat;
char *smk_default;
int smk_initialized;
spinlock_t smk_sblock; /* for initialization */
};
struct socket_smack {
char *smk_out; /* outbound label */
char *smk_in; /* inbound label */
char smk_packet[SMK_LABELLEN]; /* TCP peer label */
};
/*
* Inode smack data
*/
struct inode_smack {
char *smk_inode; /* label of the fso */
struct mutex smk_lock; /* initialization lock */
int smk_flags; /* smack inode flags */
};
#define SMK_INODE_INSTANT 0x01 /* inode is instantiated */
/*
* A label access rule.
*/
struct smack_rule {
char *smk_subject;
char *smk_object;
int smk_access;
};
/*
* An entry in the table of permitted label accesses.
*/
struct smk_list_entry {
struct smk_list_entry *smk_next;
struct smack_rule smk_rule;
};
/*
* An entry in the table mapping smack values to
* CIPSO level/category-set values.
*/
struct smack_cipso {
int smk_level;
char smk_catset[SMK_LABELLEN];
};
/*
* This is the repository for labels seen so that it is
* not necessary to keep allocating tiny chuncks of memory
* and so that they can be shared.
*
* Labels are never modified in place. Anytime a label
* is imported (e.g. xattrset on a file) the list is checked
* for it and it is added if it doesn't exist. The address
* is passed out in either case. Entries are added, but
* never deleted.
*
* Since labels are hanging around anyway it doesn't
* hurt to maintain a secid for those awkward situations
* where kernel components that ought to use LSM independent
* interfaces don't. The secid should go away when all of
* these components have been repaired.
*
* If there is a cipso value associated with the label it
* gets stored here, too. This will most likely be rare as
* the cipso direct mapping in used internally.
*/
struct smack_known {
struct smack_known *smk_next;
char smk_known[SMK_LABELLEN];
u32 smk_secid;
struct smack_cipso *smk_cipso;
spinlock_t smk_cipsolock; /* for changing cipso map */
};
/*
* Mount options
*/
#define SMK_FSDEFAULT "smackfsdef="
#define SMK_FSFLOOR "smackfsfloor="
#define SMK_FSHAT "smackfshat="
#define SMK_FSROOT "smackfsroot="
/*
* xattr names
*/
#define XATTR_SMACK_SUFFIX "SMACK64"
#define XATTR_SMACK_IPIN "SMACK64IPIN"
#define XATTR_SMACK_IPOUT "SMACK64IPOUT"
#define XATTR_NAME_SMACK XATTR_SECURITY_PREFIX XATTR_SMACK_SUFFIX
#define XATTR_NAME_SMACKIPIN XATTR_SECURITY_PREFIX XATTR_SMACK_IPIN
#define XATTR_NAME_SMACKIPOUT XATTR_SECURITY_PREFIX XATTR_SMACK_IPOUT
/*
* smackfs macic number
*/
#define SMACK_MAGIC 0x43415d53 /* "SMAC" */
/*
* A limit on the number of entries in the lists
* makes some of the list administration easier.
*/
#define SMACK_LIST_MAX 10000
/*
* CIPSO defaults.
*/
#define SMACK_CIPSO_DOI_DEFAULT 3 /* Historical */
#define SMACK_CIPSO_DIRECT_DEFAULT 250 /* Arbitrary */
#define SMACK_CIPSO_MAXCATVAL 63 /* Bigger gets harder */
#define SMACK_CIPSO_MAXLEVEL 255 /* CIPSO 2.2 standard */
#define SMACK_CIPSO_MAXCATNUM 239 /* CIPSO 2.2 standard */
/*
* Just to make the common cases easier to deal with
*/
#define MAY_ANY (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
#define MAY_ANYREAD (MAY_READ | MAY_EXEC)
#define MAY_ANYWRITE (MAY_WRITE | MAY_APPEND)
#define MAY_READWRITE (MAY_READ | MAY_WRITE)
#define MAY_NOT 0
/*
* These functions are in smack_lsm.c
*/
struct inode_smack *new_inode_smack(char *);
/*
* These functions are in smack_access.c
*/
int smk_access(char *, char *, int);
int smk_curacc(char *, u32);
int smack_to_cipso(const char *, struct smack_cipso *);
void smack_from_cipso(u32, char *, char *);
char *smack_from_secid(const u32);
char *smk_import(const char *, int);
struct smack_known *smk_import_entry(const char *, int);
u32 smack_to_secid(const char *);
/*
* Shared data.
*/
extern int smack_cipso_direct;
extern int smack_net_nltype;
extern char *smack_net_ambient;
extern struct smack_known *smack_known;
extern struct smack_known smack_known_floor;
extern struct smack_known smack_known_hat;
extern struct smack_known smack_known_huh;
extern struct smack_known smack_known_invalid;
extern struct smack_known smack_known_star;
extern struct smack_known smack_known_unset;
extern struct smk_list_entry *smack_list;
/*
* Stricly for CIPSO level manipulation.
* Set the category bit number in a smack label sized buffer.
*/
static inline void smack_catset_bit(int cat, char *catsetp)
{
if (cat > SMK_LABELLEN * 8)
return;
catsetp[(cat - 1) / 8] |= 0x80 >> ((cat - 1) % 8);
}
/*
* Present a pointer to the smack label in an inode blob.
*/
static inline char *smk_of_inode(const struct inode *isp)
{
struct inode_smack *sip = isp->i_security;
return sip->smk_inode;
}
#endif /* _SECURITY_SMACK_H */

356
security/smack/smack_access.c Normal file
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/*
* Copyright (C) 2007 Casey Schaufler <casey@schaufler-ca.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, version 2.
*
* Author:
* Casey Schaufler <casey@schaufler-ca.com>
*
*/
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include "smack.h"
struct smack_known smack_known_unset = {
.smk_next = NULL,
.smk_known = "UNSET",
.smk_secid = 1,
.smk_cipso = NULL,
};
struct smack_known smack_known_huh = {
.smk_next = &smack_known_unset,
.smk_known = "?",
.smk_secid = 2,
.smk_cipso = NULL,
};
struct smack_known smack_known_hat = {
.smk_next = &smack_known_huh,
.smk_known = "^",
.smk_secid = 3,
.smk_cipso = NULL,
};
struct smack_known smack_known_star = {
.smk_next = &smack_known_hat,
.smk_known = "*",
.smk_secid = 4,
.smk_cipso = NULL,
};
struct smack_known smack_known_floor = {
.smk_next = &smack_known_star,
.smk_known = "_",
.smk_secid = 5,
.smk_cipso = NULL,
};
struct smack_known smack_known_invalid = {
.smk_next = &smack_known_floor,
.smk_known = "",
.smk_secid = 6,
.smk_cipso = NULL,
};
struct smack_known *smack_known = &smack_known_invalid;
/*
* The initial value needs to be bigger than any of the
* known values above.
*/
static u32 smack_next_secid = 10;
/**
* smk_access - determine if a subject has a specific access to an object
* @subject_label: a pointer to the subject's Smack label
* @object_label: a pointer to the object's Smack label
* @request: the access requested, in "MAY" format
*
* This function looks up the subject/object pair in the
* access rule list and returns 0 if the access is permitted,
* non zero otherwise.
*
* Even though Smack labels are usually shared on smack_list
* labels that come in off the network can't be imported
* and added to the list for locking reasons.
*
* Therefore, it is necessary to check the contents of the labels,
* not just the pointer values. Of course, in most cases the labels
* will be on the list, so checking the pointers may be a worthwhile
* optimization.
*/
int smk_access(char *subject_label, char *object_label, int request)
{
u32 may = MAY_NOT;
struct smk_list_entry *sp;
struct smack_rule *srp;
/*
* Hardcoded comparisons.
*
* A star subject can't access any object.
*/
if (subject_label == smack_known_star.smk_known ||
strcmp(subject_label, smack_known_star.smk_known) == 0)
return -EACCES;
/*
* A star object can be accessed by any subject.
*/
if (object_label == smack_known_star.smk_known ||
strcmp(object_label, smack_known_star.smk_known) == 0)
return 0;
/*
* An object can be accessed in any way by a subject
* with the same label.
*/
if (subject_label == object_label ||
strcmp(subject_label, object_label) == 0)
return 0;
/*
* A hat subject can read any object.
* A floor object can be read by any subject.
*/
if ((request & MAY_ANYREAD) == request) {
if (object_label == smack_known_floor.smk_known ||
strcmp(object_label, smack_known_floor.smk_known) == 0)
return 0;
if (subject_label == smack_known_hat.smk_known ||
strcmp(subject_label, smack_known_hat.smk_known) == 0)
return 0;
}
/*
* Beyond here an explicit relationship is required.
* If the requested access is contained in the available
* access (e.g. read is included in readwrite) it's
* good.
*/
for (sp = smack_list; sp != NULL; sp = sp->smk_next) {
srp = &sp->smk_rule;
if (srp->smk_subject == subject_label ||
strcmp(srp->smk_subject, subject_label) == 0) {
if (srp->smk_object == object_label ||
strcmp(srp->smk_object, object_label) == 0) {
may = srp->smk_access;
break;
}
}
}
/*
* This is a bit map operation.
*/
if ((request & may) == request)
return 0;
return -EACCES;
}
/**
* smk_curacc - determine if current has a specific access to an object
* @object_label: a pointer to the object's Smack label
* @request: the access requested, in "MAY" format
*
* This function checks the current subject label/object label pair
* in the access rule list and returns 0 if the access is permitted,
* non zero otherwise. It allows that current my have the capability
* to override the rules.
*/
int smk_curacc(char *obj_label, u32 mode)
{
int rc;
rc = smk_access(current->security, obj_label, mode);
if (rc == 0)
return 0;
if (capable(CAP_MAC_OVERRIDE))
return 0;
return rc;
}
static DEFINE_MUTEX(smack_known_lock);
/**
* smk_import_entry - import a label, return the list entry
* @string: a text string that might be a Smack label
* @len: the maximum size, or zero if it is NULL terminated.
*
* Returns a pointer to the entry in the label list that
* matches the passed string, adding it if necessary.
*/
struct smack_known *smk_import_entry(const char *string, int len)
{
struct smack_known *skp;
char smack[SMK_LABELLEN];
int found;
int i;
if (len <= 0 || len > SMK_MAXLEN)
len = SMK_MAXLEN;
for (i = 0, found = 0; i < SMK_LABELLEN; i++) {
if (found)
smack[i] = '\0';
else if (i >= len || string[i] > '~' || string[i] <= ' ' ||
string[i] == '/') {
smack[i] = '\0';
found = 1;
} else
smack[i] = string[i];
}
if (smack[0] == '\0')
return NULL;
mutex_lock(&smack_known_lock);
for (skp = smack_known; skp != NULL; skp = skp->smk_next)
if (strncmp(skp->smk_known, smack, SMK_MAXLEN) == 0)
break;
if (skp == NULL) {
skp = kzalloc(sizeof(struct smack_known), GFP_KERNEL);
if (skp != NULL) {
skp->smk_next = smack_known;
strncpy(skp->smk_known, smack, SMK_MAXLEN);
skp->smk_secid = smack_next_secid++;
skp->smk_cipso = NULL;
spin_lock_init(&skp->smk_cipsolock);
/*
* Make sure that the entry is actually
* filled before putting it on the list.
*/
smp_mb();
smack_known = skp;
}
}
mutex_unlock(&smack_known_lock);
return skp;
}
/**
* smk_import - import a smack label
* @string: a text string that might be a Smack label
* @len: the maximum size, or zero if it is NULL terminated.
*
* Returns a pointer to the label in the label list that
* matches the passed string, adding it if necessary.
*/
char *smk_import(const char *string, int len)
{
struct smack_known *skp;
skp = smk_import_entry(string, len);
if (skp == NULL)
return NULL;
return skp->smk_known;
}
/**
* smack_from_secid - find the Smack label associated with a secid
* @secid: an integer that might be associated with a Smack label
*
* Returns a pointer to the appropraite Smack label if there is one,
* otherwise a pointer to the invalid Smack label.
*/
char *smack_from_secid(const u32 secid)
{
struct smack_known *skp;
for (skp = smack_known; skp != NULL; skp = skp->smk_next)
if (skp->smk_secid == secid)
return skp->smk_known;
/*
* If we got this far someone asked for the translation
* of a secid that is not on the list.
*/
return smack_known_invalid.smk_known;
}
/**
* smack_to_secid - find the secid associated with a Smack label
* @smack: the Smack label
*
* Returns the appropriate secid if there is one,
* otherwise 0
*/
u32 smack_to_secid(const char *smack)
{
struct smack_known *skp;
for (skp = smack_known; skp != NULL; skp = skp->smk_next)
if (strncmp(skp->smk_known, smack, SMK_MAXLEN) == 0)
return skp->smk_secid;
return 0;
}
/**
* smack_from_cipso - find the Smack label associated with a CIPSO option
* @level: Bell & LaPadula level from the network
* @cp: Bell & LaPadula categories from the network
* @result: where to put the Smack value
*
* This is a simple lookup in the label table.
*
* This is an odd duck as far as smack handling goes in that
* it sends back a copy of the smack label rather than a pointer
* to the master list. This is done because it is possible for
* a foreign host to send a smack label that is new to this
* machine and hence not on the list. That would not be an
* issue except that adding an entry to the master list can't
* be done at that point.
*/
void smack_from_cipso(u32 level, char *cp, char *result)
{
struct smack_known *kp;
char *final = NULL;
for (kp = smack_known; final == NULL && kp != NULL; kp = kp->smk_next) {
if (kp->smk_cipso == NULL)
continue;
spin_lock_bh(&kp->smk_cipsolock);
if (kp->smk_cipso->smk_level == level &&
memcmp(kp->smk_cipso->smk_catset, cp, SMK_LABELLEN) == 0)
final = kp->smk_known;
spin_unlock_bh(&kp->smk_cipsolock);
}
if (final == NULL)
final = smack_known_huh.smk_known;
strncpy(result, final, SMK_MAXLEN);
return;
}
/**
* smack_to_cipso - find the CIPSO option to go with a Smack label
* @smack: a pointer to the smack label in question
* @cp: where to put the result
*
* Returns zero if a value is available, non-zero otherwise.
*/
int smack_to_cipso(const char *smack, struct smack_cipso *cp)
{
struct smack_known *kp;
for (kp = smack_known; kp != NULL; kp = kp->smk_next)
if (kp->smk_known == smack ||
strcmp(kp->smk_known, smack) == 0)
break;
if (kp == NULL || kp->smk_cipso == NULL)
return -ENOENT;
memcpy(cp, kp->smk_cipso, sizeof(struct smack_cipso));
return 0;
}

2518
security/smack/smack_lsm.c Normal file
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981
security/smack/smackfs.c Normal file
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/*
* Copyright (C) 2007 Casey Schaufler <casey@schaufler-ca.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, version 2.
*
* Authors:
* Casey Schaufler <casey@schaufler-ca.com>
* Ahmed S. Darwish <darwish.07@gmail.com>
*
* Special thanks to the authors of selinuxfs.
*
* Karl MacMillan <kmacmillan@tresys.com>
* James Morris <jmorris@redhat.com>
*
*/
#include <linux/kernel.h>
#include <linux/vmalloc.h>
#include <linux/security.h>
#include <linux/mutex.h>
#include <net/netlabel.h>
#include <net/cipso_ipv4.h>
#include <linux/seq_file.h>
#include <linux/ctype.h>
#include "smack.h"
/*
* smackfs pseudo filesystem.
*/
enum smk_inos {
SMK_ROOT_INO = 2,
SMK_LOAD = 3, /* load policy */
SMK_CIPSO = 4, /* load label -> CIPSO mapping */
SMK_DOI = 5, /* CIPSO DOI */
SMK_DIRECT = 6, /* CIPSO level indicating direct label */
SMK_AMBIENT = 7, /* internet ambient label */
SMK_NLTYPE = 8, /* label scheme to use by default */
};
/*
* List locks
*/
static DEFINE_MUTEX(smack_list_lock);
static DEFINE_MUTEX(smack_cipso_lock);
/*
* This is the "ambient" label for network traffic.
* If it isn't somehow marked, use this.
* It can be reset via smackfs/ambient
*/
char *smack_net_ambient = smack_known_floor.smk_known;
/*
* This is the default packet marking scheme for network traffic.
* It can be reset via smackfs/nltype
*/
int smack_net_nltype = NETLBL_NLTYPE_CIPSOV4;
/*
* This is the level in a CIPSO header that indicates a
* smack label is contained directly in the category set.
* It can be reset via smackfs/direct
*/
int smack_cipso_direct = SMACK_CIPSO_DIRECT_DEFAULT;
static int smk_cipso_doi_value = SMACK_CIPSO_DOI_DEFAULT;
struct smk_list_entry *smack_list;
#define SEQ_READ_FINISHED 1
/*
* Disable concurrent writing open() operations
*/
static struct semaphore smack_write_sem;
/*
* Values for parsing cipso rules
* SMK_DIGITLEN: Length of a digit field in a rule.
* SMK_CIPSOMEN: Minimum possible cipso rule length.
*/
#define SMK_DIGITLEN 4
#define SMK_CIPSOMIN (SMK_MAXLEN + 2 * SMK_DIGITLEN)
/*
* Seq_file read operations for /smack/load
*/
static void *load_seq_start(struct seq_file *s, loff_t *pos)
{
if (*pos == SEQ_READ_FINISHED)
return NULL;
return smack_list;
}
static void *load_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
struct smk_list_entry *skp = ((struct smk_list_entry *) v)->smk_next;
if (skp == NULL)
*pos = SEQ_READ_FINISHED;
return skp;
}
static int load_seq_show(struct seq_file *s, void *v)
{
struct smk_list_entry *slp = (struct smk_list_entry *) v;
struct smack_rule *srp = &slp->smk_rule;
seq_printf(s, "%s %s", (char *)srp->smk_subject,
(char *)srp->smk_object);
seq_putc(s, ' ');
if (srp->smk_access & MAY_READ)
seq_putc(s, 'r');
if (srp->smk_access & MAY_WRITE)
seq_putc(s, 'w');
if (srp->smk_access & MAY_EXEC)
seq_putc(s, 'x');
if (srp->smk_access & MAY_APPEND)
seq_putc(s, 'a');
if (srp->smk_access == 0)
seq_putc(s, '-');
seq_putc(s, '\n');
return 0;
}
static void load_seq_stop(struct seq_file *s, void *v)
{
/* No-op */
}
static struct seq_operations load_seq_ops = {
.start = load_seq_start,
.next = load_seq_next,
.show = load_seq_show,
.stop = load_seq_stop,
};
/**
* smk_open_load - open() for /smack/load
* @inode: inode structure representing file
* @file: "load" file pointer
*
* For reading, use load_seq_* seq_file reading operations.
*/
static int smk_open_load(struct inode *inode, struct file *file)
{
if ((file->f_flags & O_ACCMODE) == O_RDONLY)
return seq_open(file, &load_seq_ops);
if (down_interruptible(&smack_write_sem))
return -ERESTARTSYS;
return 0;
}
/**
* smk_release_load - release() for /smack/load
* @inode: inode structure representing file
* @file: "load" file pointer
*
* For a reading session, use the seq_file release
* implementation.
* Otherwise, we are at the end of a writing session so
* clean everything up.
*/
static int smk_release_load(struct inode *inode, struct file *file)
{
if ((file->f_flags & O_ACCMODE) == O_RDONLY)
return seq_release(inode, file);
up(&smack_write_sem);
return 0;
}
/**
* smk_set_access - add a rule to the rule list
* @srp: the new rule to add
*
* Looks through the current subject/object/access list for
* the subject/object pair and replaces the access that was
* there. If the pair isn't found add it with the specified
* access.
*/
static void smk_set_access(struct smack_rule *srp)
{
struct smk_list_entry *sp;
struct smk_list_entry *newp;
mutex_lock(&smack_list_lock);
for (sp = smack_list; sp != NULL; sp = sp->smk_next)
if (sp->smk_rule.smk_subject == srp->smk_subject &&
sp->smk_rule.smk_object == srp->smk_object) {
sp->smk_rule.smk_access = srp->smk_access;
break;
}
if (sp == NULL) {
newp = kzalloc(sizeof(struct smk_list_entry), GFP_KERNEL);
newp->smk_rule = *srp;
newp->smk_next = smack_list;
smack_list = newp;
}
mutex_unlock(&smack_list_lock);
return;
}
/**
* smk_write_load - write() for /smack/load
* @filp: file pointer, not actually used
* @buf: where to get the data from
* @count: bytes sent
* @ppos: where to start - must be 0
*
* Get one smack access rule from above.
* The format is exactly:
* char subject[SMK_LABELLEN]
* char object[SMK_LABELLEN]
* char access[SMK_ACCESSKINDS]
*
* Anything following is commentary and ignored.
*
* writes must be SMK_LABELLEN+SMK_LABELLEN+4 bytes.
*/
#define MINIMUM_LOAD (SMK_LABELLEN + SMK_LABELLEN + SMK_ACCESSKINDS)
static ssize_t smk_write_load(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
struct smack_rule rule;
char *data;
int rc = -EINVAL;
/*
* Must have privilege.
* No partial writes.
* Enough data must be present.
*/
if (!capable(CAP_MAC_ADMIN))
return -EPERM;
if (*ppos != 0)
return -EINVAL;
if (count < MINIMUM_LOAD)
return -EINVAL;
data = kzalloc(count, GFP_KERNEL);
if (data == NULL)
return -ENOMEM;
if (copy_from_user(data, buf, count) != 0) {
rc = -EFAULT;
goto out;
}
rule.smk_subject = smk_import(data, 0);
if (rule.smk_subject == NULL)
goto out;
rule.smk_object = smk_import(data + SMK_LABELLEN, 0);
if (rule.smk_object == NULL)
goto out;
rule.smk_access = 0;
switch (data[SMK_LABELLEN + SMK_LABELLEN]) {
case '-':
break;
case 'r':
case 'R':
rule.smk_access |= MAY_READ;
break;
default:
goto out;
}
switch (data[SMK_LABELLEN + SMK_LABELLEN + 1]) {
case '-':
break;
case 'w':
case 'W':
rule.smk_access |= MAY_WRITE;
break;
default:
goto out;
}
switch (data[SMK_LABELLEN + SMK_LABELLEN + 2]) {
case '-':
break;
case 'x':
case 'X':
rule.smk_access |= MAY_EXEC;
break;
default:
goto out;
}
switch (data[SMK_LABELLEN + SMK_LABELLEN + 3]) {
case '-':
break;
case 'a':
case 'A':
rule.smk_access |= MAY_READ;
break;
default:
goto out;
}
smk_set_access(&rule);
rc = count;
out:
kfree(data);
return rc;
}
static const struct file_operations smk_load_ops = {
.open = smk_open_load,
.read = seq_read,
.llseek = seq_lseek,
.write = smk_write_load,
.release = smk_release_load,
};
/**
* smk_cipso_doi - initialize the CIPSO domain
*/
void smk_cipso_doi(void)
{
int rc;
struct cipso_v4_doi *doip;
struct netlbl_audit audit_info;
rc = netlbl_cfg_map_del(NULL, &audit_info);
if (rc != 0)
printk(KERN_WARNING "%s:%d remove rc = %d\n",
__func__, __LINE__, rc);
doip = kmalloc(sizeof(struct cipso_v4_doi), GFP_KERNEL);
if (doip == NULL)
panic("smack: Failed to initialize cipso DOI.\n");
doip->map.std = NULL;
doip->doi = smk_cipso_doi_value;
doip->type = CIPSO_V4_MAP_PASS;
doip->tags[0] = CIPSO_V4_TAG_RBITMAP;
for (rc = 1; rc < CIPSO_V4_TAG_MAXCNT; rc++)
doip->tags[rc] = CIPSO_V4_TAG_INVALID;
rc = netlbl_cfg_cipsov4_add_map(doip, NULL, &audit_info);
if (rc != 0)
printk(KERN_WARNING "%s:%d add rc = %d\n",
__func__, __LINE__, rc);
}
/*
* Seq_file read operations for /smack/cipso
*/
static void *cipso_seq_start(struct seq_file *s, loff_t *pos)
{
if (*pos == SEQ_READ_FINISHED)
return NULL;
return smack_known;
}
static void *cipso_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
struct smack_known *skp = ((struct smack_known *) v)->smk_next;
/*
* Omit labels with no associated cipso value
*/
while (skp != NULL && !skp->smk_cipso)
skp = skp->smk_next;
if (skp == NULL)
*pos = SEQ_READ_FINISHED;
return skp;
}
/*
* Print cipso labels in format:
* label level[/cat[,cat]]
*/
static int cipso_seq_show(struct seq_file *s, void *v)
{
struct smack_known *skp = (struct smack_known *) v;
struct smack_cipso *scp = skp->smk_cipso;
char *cbp;
char sep = '/';
int cat = 1;
int i;
unsigned char m;
if (scp == NULL)
return 0;
seq_printf(s, "%s %3d", (char *)&skp->smk_known, scp->smk_level);
cbp = scp->smk_catset;
for (i = 0; i < SMK_LABELLEN; i++)
for (m = 0x80; m != 0; m >>= 1) {
if (m & cbp[i]) {
seq_printf(s, "%c%d", sep, cat);
sep = ',';
}
cat++;
}
seq_putc(s, '\n');
return 0;
}
static void cipso_seq_stop(struct seq_file *s, void *v)
{
/* No-op */
}
static struct seq_operations cipso_seq_ops = {
.start = cipso_seq_start,
.stop = cipso_seq_stop,
.next = cipso_seq_next,
.show = cipso_seq_show,
};
/**
* smk_open_cipso - open() for /smack/cipso
* @inode: inode structure representing file
* @file: "cipso" file pointer
*
* Connect our cipso_seq_* operations with /smack/cipso
* file_operations
*/
static int smk_open_cipso(struct inode *inode, struct file *file)
{
return seq_open(file, &cipso_seq_ops);
}
/**
* smk_write_cipso - write() for /smack/cipso
* @filp: file pointer, not actually used
* @buf: where to get the data from
* @count: bytes sent
* @ppos: where to start
*
* Accepts only one cipso rule per write call.
* Returns number of bytes written or error code, as appropriate
*/
static ssize_t smk_write_cipso(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
struct smack_known *skp;
struct smack_cipso *scp = NULL;
char mapcatset[SMK_LABELLEN];
int maplevel;
int cat;
int catlen;
ssize_t rc = -EINVAL;
char *data = NULL;
char *rule;
int ret;
int i;
/*
* Must have privilege.
* No partial writes.
* Enough data must be present.
*/
if (!capable(CAP_MAC_ADMIN))
return -EPERM;
if (*ppos != 0)
return -EINVAL;
if (count <= SMK_CIPSOMIN)
return -EINVAL;
data = kzalloc(count + 1, GFP_KERNEL);
if (data == NULL)
return -ENOMEM;
if (copy_from_user(data, buf, count) != 0) {
rc = -EFAULT;
goto unlockedout;
}
data[count] = '\0';
rule = data;
/*
* Only allow one writer at a time. Writes should be
* quite rare and small in any case.
*/
mutex_lock(&smack_cipso_lock);
skp = smk_import_entry(rule, 0);
if (skp == NULL)
goto out;
rule += SMK_LABELLEN;;
ret = sscanf(rule, "%d", &maplevel);
if (ret != 1 || maplevel > SMACK_CIPSO_MAXLEVEL)
goto out;
rule += SMK_DIGITLEN;
ret = sscanf(rule, "%d", &catlen);
if (ret != 1 || catlen > SMACK_CIPSO_MAXCATNUM)
goto out;
if (count <= (SMK_CIPSOMIN + catlen * SMK_DIGITLEN))
goto out;
memset(mapcatset, 0, sizeof(mapcatset));
for (i = 0; i < catlen; i++) {
rule += SMK_DIGITLEN;
ret = sscanf(rule, "%d", &cat);
if (ret != 1 || cat > SMACK_CIPSO_MAXCATVAL)
goto out;
smack_catset_bit(cat, mapcatset);
}
if (skp->smk_cipso == NULL) {
scp = kzalloc(sizeof(struct smack_cipso), GFP_KERNEL);
if (scp == NULL) {
rc = -ENOMEM;
goto out;
}
}
spin_lock_bh(&skp->smk_cipsolock);
if (scp == NULL)
scp = skp->smk_cipso;
else
skp->smk_cipso = scp;
scp->smk_level = maplevel;
memcpy(scp->smk_catset, mapcatset, sizeof(mapcatset));
spin_unlock_bh(&skp->smk_cipsolock);
rc = count;
out:
mutex_unlock(&smack_cipso_lock);
unlockedout:
kfree(data);
return rc;
}
static const struct file_operations smk_cipso_ops = {
.open = smk_open_cipso,
.read = seq_read,
.llseek = seq_lseek,
.write = smk_write_cipso,
.release = seq_release,
};
/**
* smk_read_doi - read() for /smack/doi
* @filp: file pointer, not actually used
* @buf: where to put the result
* @count: maximum to send along
* @ppos: where to start
*
* Returns number of bytes read or error code, as appropriate
*/
static ssize_t smk_read_doi(struct file *filp, char __user *buf,
size_t count, loff_t *ppos)
{
char temp[80];
ssize_t rc;
if (*ppos != 0)
return 0;
sprintf(temp, "%d", smk_cipso_doi_value);
rc = simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));
return rc;
}
/**
* smk_write_doi - write() for /smack/doi
* @filp: file pointer, not actually used
* @buf: where to get the data from
* @count: bytes sent
* @ppos: where to start
*
* Returns number of bytes written or error code, as appropriate
*/
static ssize_t smk_write_doi(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
char temp[80];
int i;
if (!capable(CAP_MAC_ADMIN))
return -EPERM;
if (count >= sizeof(temp) || count == 0)
return -EINVAL;
if (copy_from_user(temp, buf, count) != 0)
return -EFAULT;
temp[count] = '\0';
if (sscanf(temp, "%d", &i) != 1)
return -EINVAL;
smk_cipso_doi_value = i;
smk_cipso_doi();
return count;
}
static const struct file_operations smk_doi_ops = {
.read = smk_read_doi,
.write = smk_write_doi,
};
/**
* smk_read_direct - read() for /smack/direct
* @filp: file pointer, not actually used
* @buf: where to put the result
* @count: maximum to send along
* @ppos: where to start
*
* Returns number of bytes read or error code, as appropriate
*/
static ssize_t smk_read_direct(struct file *filp, char __user *buf,
size_t count, loff_t *ppos)
{
char temp[80];
ssize_t rc;
if (*ppos != 0)
return 0;
sprintf(temp, "%d", smack_cipso_direct);
rc = simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));
return rc;
}
/**
* smk_write_direct - write() for /smack/direct
* @filp: file pointer, not actually used
* @buf: where to get the data from
* @count: bytes sent
* @ppos: where to start
*
* Returns number of bytes written or error code, as appropriate
*/
static ssize_t smk_write_direct(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
char temp[80];
int i;
if (!capable(CAP_MAC_ADMIN))
return -EPERM;
if (count >= sizeof(temp) || count == 0)
return -EINVAL;
if (copy_from_user(temp, buf, count) != 0)
return -EFAULT;
temp[count] = '\0';
if (sscanf(temp, "%d", &i) != 1)
return -EINVAL;
smack_cipso_direct = i;
return count;
}
static const struct file_operations smk_direct_ops = {
.read = smk_read_direct,
.write = smk_write_direct,
};
/**
* smk_read_ambient - read() for /smack/ambient
* @filp: file pointer, not actually used
* @buf: where to put the result
* @cn: maximum to send along
* @ppos: where to start
*
* Returns number of bytes read or error code, as appropriate
*/
static ssize_t smk_read_ambient(struct file *filp, char __user *buf,
size_t cn, loff_t *ppos)
{
ssize_t rc;
char out[SMK_LABELLEN];
int asize;
if (*ppos != 0)
return 0;
/*
* Being careful to avoid a problem in the case where
* smack_net_ambient gets changed in midstream.
* Since smack_net_ambient is always set with a value
* from the label list, including initially, and those
* never get freed, the worst case is that the pointer
* gets changed just after this strncpy, in which case
* the value passed up is incorrect. Locking around
* smack_net_ambient wouldn't be any better than this
* copy scheme as by the time the caller got to look
* at the ambient value it would have cleared the lock
* and been changed.
*/
strncpy(out, smack_net_ambient, SMK_LABELLEN);
asize = strlen(out) + 1;
if (cn < asize)
return -EINVAL;
rc = simple_read_from_buffer(buf, cn, ppos, out, asize);
return rc;
}
/**
* smk_write_ambient - write() for /smack/ambient
* @filp: file pointer, not actually used
* @buf: where to get the data from
* @count: bytes sent
* @ppos: where to start
*
* Returns number of bytes written or error code, as appropriate
*/
static ssize_t smk_write_ambient(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
char in[SMK_LABELLEN];
char *smack;
if (!capable(CAP_MAC_ADMIN))
return -EPERM;
if (count >= SMK_LABELLEN)
return -EINVAL;
if (copy_from_user(in, buf, count) != 0)
return -EFAULT;
smack = smk_import(in, count);
if (smack == NULL)
return -EINVAL;
smack_net_ambient = smack;
return count;
}
static const struct file_operations smk_ambient_ops = {
.read = smk_read_ambient,
.write = smk_write_ambient,
};
struct option_names {
int o_number;
char *o_name;
char *o_alias;
};
static struct option_names netlbl_choices[] = {
{ NETLBL_NLTYPE_RIPSO,
NETLBL_NLTYPE_RIPSO_NAME, "ripso" },
{ NETLBL_NLTYPE_CIPSOV4,
NETLBL_NLTYPE_CIPSOV4_NAME, "cipsov4" },
{ NETLBL_NLTYPE_CIPSOV4,
NETLBL_NLTYPE_CIPSOV4_NAME, "cipso" },
{ NETLBL_NLTYPE_CIPSOV6,
NETLBL_NLTYPE_CIPSOV6_NAME, "cipsov6" },
{ NETLBL_NLTYPE_UNLABELED,
NETLBL_NLTYPE_UNLABELED_NAME, "unlabeled" },
};
/**
* smk_read_nltype - read() for /smack/nltype
* @filp: file pointer, not actually used
* @buf: where to put the result
* @count: maximum to send along
* @ppos: where to start
*
* Returns number of bytes read or error code, as appropriate
*/
static ssize_t smk_read_nltype(struct file *filp, char __user *buf,
size_t count, loff_t *ppos)
{
char bound[40];
ssize_t rc;
int i;
if (count < SMK_LABELLEN)
return -EINVAL;
if (*ppos != 0)
return 0;
sprintf(bound, "unknown");
for (i = 0; i < ARRAY_SIZE(netlbl_choices); i++)
if (smack_net_nltype == netlbl_choices[i].o_number) {
sprintf(bound, "%s", netlbl_choices[i].o_name);
break;
}
rc = simple_read_from_buffer(buf, count, ppos, bound, strlen(bound));
return rc;
}
/**
* smk_write_nltype - write() for /smack/nltype
* @filp: file pointer, not actually used
* @buf: where to get the data from
* @count: bytes sent
* @ppos: where to start
*
* Returns number of bytes written or error code, as appropriate
*/
static ssize_t smk_write_nltype(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
char bound[40];
char *cp;
int i;
if (!capable(CAP_MAC_ADMIN))
return -EPERM;
if (count >= 40)
return -EINVAL;
if (copy_from_user(bound, buf, count) != 0)
return -EFAULT;
bound[count] = '\0';
cp = strchr(bound, ' ');
if (cp != NULL)
*cp = '\0';
cp = strchr(bound, '\n');
if (cp != NULL)
*cp = '\0';
for (i = 0; i < ARRAY_SIZE(netlbl_choices); i++)
if (strcmp(bound, netlbl_choices[i].o_name) == 0 ||
strcmp(bound, netlbl_choices[i].o_alias) == 0) {
smack_net_nltype = netlbl_choices[i].o_number;
return count;
}
/*
* Not a valid choice.
*/
return -EINVAL;
}
static const struct file_operations smk_nltype_ops = {
.read = smk_read_nltype,
.write = smk_write_nltype,
};
/**
* smk_fill_super - fill the /smackfs superblock
* @sb: the empty superblock
* @data: unused
* @silent: unused
*
* Fill in the well known entries for /smack
*
* Returns 0 on success, an error code on failure
*/
static int smk_fill_super(struct super_block *sb, void *data, int silent)
{
int rc;
struct inode *root_inode;
static struct tree_descr smack_files[] = {
[SMK_LOAD] =
{"load", &smk_load_ops, S_IRUGO|S_IWUSR},
[SMK_CIPSO] =
{"cipso", &smk_cipso_ops, S_IRUGO|S_IWUSR},
[SMK_DOI] =
{"doi", &smk_doi_ops, S_IRUGO|S_IWUSR},
[SMK_DIRECT] =
{"direct", &smk_direct_ops, S_IRUGO|S_IWUSR},
[SMK_AMBIENT] =
{"ambient", &smk_ambient_ops, S_IRUGO|S_IWUSR},
[SMK_NLTYPE] =
{"nltype", &smk_nltype_ops, S_IRUGO|S_IWUSR},
/* last one */ {""}
};
rc = simple_fill_super(sb, SMACK_MAGIC, smack_files);
if (rc != 0) {
printk(KERN_ERR "%s failed %d while creating inodes\n",
__func__, rc);
return rc;
}
root_inode = sb->s_root->d_inode;
root_inode->i_security = new_inode_smack(smack_known_floor.smk_known);
return 0;
}
/**
* smk_get_sb - get the smackfs superblock
* @fs_type: passed along without comment
* @flags: passed along without comment
* @dev_name: passed along without comment
* @data: passed along without comment
* @mnt: passed along without comment
*
* Just passes everything along.
*
* Returns what the lower level code does.
*/
static int smk_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data,
struct vfsmount *mnt)
{
return get_sb_single(fs_type, flags, data, smk_fill_super, mnt);
}
static struct file_system_type smk_fs_type = {
.name = "smackfs",
.get_sb = smk_get_sb,
.kill_sb = kill_litter_super,
};
static struct vfsmount *smackfs_mount;
/**
* init_smk_fs - get the smackfs superblock
*
* register the smackfs
*
* Returns 0 unless the registration fails.
*/
static int __init init_smk_fs(void)
{
int err;
err = register_filesystem(&smk_fs_type);
if (!err) {
smackfs_mount = kern_mount(&smk_fs_type);
if (IS_ERR(smackfs_mount)) {
printk(KERN_ERR "smackfs: could not mount!\n");
err = PTR_ERR(smackfs_mount);
smackfs_mount = NULL;
}
}
sema_init(&smack_write_sem, 1);
smk_cipso_doi();
return err;
}
__initcall(init_smk_fs);