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2014-08-29Make Smack operate on smack_known struct where it still used char*Lukasz Pawelczyk
Smack used to use a mix of smack_known struct and char* throughout its APIs and implementation. This patch unifies the behaviour and makes it store and operate exclusively on smack_known struct pointers when managing labels. Signed-off-by: Lukasz Pawelczyk <l.pawelczyk@samsung.com> Conflicts: security/smack/smack_access.c security/smack/smack_lsm.c
2014-08-28Smack: Bring-up access modeCasey Schaufler
People keep asking me for permissive mode, and I keep saying "no". Permissive mode is wrong for more reasons than I can enumerate, but the compelling one is that it's once on, never off. Nonetheless, there is an argument to be made for running a process with lots of permissions, logging which are required, and then locking the process down. There wasn't a way to do that with Smack, but this provides it. The notion is that you start out by giving the process an appropriate Smack label, such as "ATBirds". You create rules with a wide range of access and the "b" mode. On Tizen it might be: ATBirds System rwxalb ATBirds User rwxalb ATBirds _ rwxalb User ATBirds wb System ATBirds wb Accesses that fail will generate audit records. Accesses that succeed because of rules marked with a "b" generate log messages identifying the rule, the program and as much object information as is convenient. When the system is properly configured and the programs brought in line with the labeling scheme the "b" mode can be removed from the rules. When the system is ready for production the facility can be configured out. This provides the developer the convenience of permissive mode without creating a system that looks like it is enforcing a policy while it is not. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2014-04-11Smack: bidirectional UDS connect checkCasey Schaufler
Smack IPC policy requires that the sender have write access to the receiver. UDS streams don't do per-packet checks. The only check is done at connect time. The existing code checks if the connecting process can write to the other, but not the other way around. This change adds a check that the other end can write to the connecting process. Targeted for git://git.gitorious.org/smack-next/kernel.git Signed-off-by: Casey Schuafler <casey@schaufler-ca.com>
2014-04-11Smack: adds smackfs/ptrace interfaceLukasz Pawelczyk
This allows to limit ptrace beyond the regular smack access rules. It adds a smackfs/ptrace interface that allows smack to be configured to require equal smack labels for PTRACE_MODE_ATTACH access. See the changes in Documentation/security/Smack.txt below for details. Signed-off-by: Lukasz Pawelczyk <l.pawelczyk@partner.samsung.com> Signed-off-by: Rafal Krypa <r.krypa@samsung.com>
2014-04-11Smack: fix the subject/object order in smack_ptrace_traceme()Lukasz Pawelczyk
The order of subject/object is currently reversed in smack_ptrace_traceme(). It is currently checked if the tracee has a capability to trace tracer and according to this rule a decision is made whether the tracer will be allowed to trace tracee. Signed-off-by: Lukasz Pawelczyk <l.pawelczyk@partner.samsung.com> Signed-off-by: Rafal Krypa <r.krypa@samsung.com>
2013-12-23Smack: Make the syslog control configurableCasey Schaufler
The syslog control requires that the calling proccess have the floor ("_") Smack label. Tizen does not run any processes except for kernel helpers with the floor label. This changes allows the admin to configure a specific label for syslog. The default value is the star ("*") label, effectively removing the restriction. The value can be set using smackfs/syslog for anyone who wants a more restrictive behavior. Targeted for git://git.gitorious.org/smack-next/kernel.git Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2013-10-18Smack: Implement lock security modeCasey Schaufler
Linux file locking does not follow the same rules as other mechanisms. Even though it is a write operation a process can set a read lock on files which it has open only for read access. Two programs with read access to a file can use read locks to communicate. This is not acceptable in a Mandatory Access Control environment. Smack treats setting a read lock as the write operation that it is. Unfortunately, many programs assume that setting a read lock is a read operation. These programs are unhappy in the Smack environment. This patch introduces a new access mode (lock) to address this problem. A process with lock access to a file can set a read lock. A process with write access to a file can set a read lock or a write lock. This prevents a situation where processes are granted write access just so they can set read locks. Targeted for git://git.gitorious.org/smack-next/kernel.git Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2013-08-01Smack: network label match fixCasey Schaufler
The Smack code that matches incoming CIPSO tags with Smack labels reaches through the NetLabel interfaces and compares the network data with the CIPSO header associated with a Smack label. This was done in a ill advised attempt to optimize performance. It works so long as the categories fit in a single capset, but this isn't always the case. This patch changes the Smack code to use the appropriate NetLabel interfaces to compare the incoming CIPSO header with the CIPSO header associated with a label. It will always match the CIPSO headers correctly. Targeted for git://git.gitorious.org/smack-next/kernel.git Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2013-08-01security: smack: add a hash table to quicken smk_find_entry()Tomasz Stanislawski
Accepted for the smack-next tree after changing the number of slots from 128 to 16. This patch adds a hash table to quicken searching of a smack label by its name. Basically, the patch improves performance of SMACK initialization. Parsing of rules involves translation from a string to a smack_known (aka label) entity which is done in smk_find_entry(). The current implementation of the function iterates over a global list of smack_known resulting in O(N) complexity for smk_find_entry(). The total complexity of SMACK initialization becomes O(rules * labels). Therefore it scales quadratically with a complexity of a system. Applying the patch reduced the complexity of smk_find_entry() to O(1) as long as number of label is in hundreds. If the number of labels is increased please update SMACK_HASH_SLOTS constant defined in security/smack/smack.h. Introducing the configuration of this constant with Kconfig or cmdline might be a good idea. The size of the hash table was adjusted experimentally. The rule set used by TIZEN contains circa 17K rules for 500 labels. The table above contains results of SMACK initialization using 'time smackctl apply' bash command. The 'Ref' is a kernel without this patch applied. The consecutive values refers to value of SMACK_HASH_SLOTS. Every measurement was repeated three times to reduce noise. | Ref | 1 | 2 | 4 | 8 | 16 | 32 | 64 | 128 | 256 | 512 -------------------------------------------------------------------------------------------- Run1 | 1.156 | 1.096 | 0.883 | 0.764 | 0.692 | 0.667 | 0.649 | 0.633 | 0.634 | 0.629 | 0.620 Run2 | 1.156 | 1.111 | 0.885 | 0.764 | 0.694 | 0.661 | 0.649 | 0.651 | 0.634 | 0.638 | 0.623 Run3 | 1.160 | 1.107 | 0.886 | 0.764 | 0.694 | 0.671 | 0.661 | 0.638 | 0.631 | 0.624 | 0.638 AVG | 1.157 | 1.105 | 0.885 | 0.764 | 0.693 | 0.666 | 0.653 | 0.641 | 0.633 | 0.630 | 0.627 Surprisingly, a single hlist is slightly faster than a double-linked list. The speed-up saturates near 64 slots. Therefore I chose value 128 to provide some margin if more labels were used. It looks that IO becomes a new bottleneck. Signed-off-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
2013-05-28Smack: Add smkfstransmute mount optionCasey Schaufler
Suppliment the smkfsroot mount option with another, smkfstransmute, that does the same thing but also marks the root inode as transmutting. This allows a freshly created filesystem to be mounted with a transmutting heirarchy. Targeted for git://git.gitorious.org/smack-next/kernel.git Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2013-05-28Smack: Improve access check performanceCasey Schaufler
Each Smack label that the kernel has seen is added to a list of labels. The list of access rules for a given subject label hangs off of the label list entry for the label. This patch changes the structures that contain subject labels to point at the label list entry rather that the label itself. Doing so removes a label list lookup in smk_access() that was accounting for the largest single chunk of Smack overhead. Targeted for git://git.gitorious.org/smack-next/kernel.git Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2013-05-28Smack: Local IPv6 port based controlsCasey Schaufler
Smack does not provide access controls on IPv6 communications. This patch introduces a mechanism for maintaining Smack lables for local IPv6 communications. It is based on labeling local ports. The behavior should be compatible with any future "real" IPv6 support as it provides no interfaces for users to manipulate the labeling. Remote IPv6 connections use the ambient label the same way that unlabeled IPv4 packets are treated. Targeted for git://git.gitorious.org/smack-next/kernel.git Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2013-03-19smack: SMACK_MAGIC to include/uapi/linux/magic.hJarkko Sakkinen
SMACK_MAGIC moved to a proper place for easy user space access (i.e. libsmack). Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@iki.fi>
2012-07-13Smack: onlycap limits on CAP_MAC_ADMINCasey Schaufler
Smack is integrated with the POSIX capabilities scheme, using the capabilities CAP_MAC_OVERRIDE and CAP_MAC_ADMIN to determine if a process is allowed to ignore Smack checks or change Smack related data respectively. Smack provides an additional restriction that if an onlycap value is set by writing to /smack/onlycap only tasks with that Smack label are allowed to use CAP_MAC_OVERRIDE. This change adds CAP_MAC_ADMIN as a capability that is affected by the onlycap mechanism. Targeted for git://git.gitorious.org/smack-next/kernel.git Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2012-07-13Smack: fix smack_new_inode bogositiesCasey Schaufler
In January of 2012 Al Viro pointed out three bits of code that he titled "new_inode_smack bogosities". This patch repairs these errors. 1. smack_sb_kern_mount() included a NULL check that is impossible. The check and NULL case are removed. 2. smack_kb_kern_mount() included pointless locking. The locking is removed. Since this is the only place that lock was used the lock is removed from the superblock_smack structure. 3. smk_fill_super() incorrectly and unnecessarily set the Smack label for the smackfs root inode. The assignment has been removed. Targeted for git://gitorious.org/smack-next/kernel.git Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2012-05-22Merge branch 'master' of git://git.infradead.org/users/eparis/selinux into nextJames Morris
Per pull request, for 3.5.
2012-05-14Smack: allow for significantly longer Smack labels v4Casey Schaufler
V4 updated to current linux-security#next Targeted for git://gitorious.org/smack-next/kernel.git Modern application runtime environments like to use naming schemes that are structured and generated without human intervention. Even though the Smack limit of 23 characters for a label name is perfectly rational for human use there have been complaints that the limit is a problem in environments where names are composed from a set or sources, including vendor, author, distribution channel and application name. Names like softwarehouse-pgwodehouse-coolappstore-mellowmuskrats are becoming harder to avoid. This patch introduces long label support in Smack. Labels are now limited to 255 characters instead of the old 23. The primary reason for limiting the labels to 23 characters was so they could be directly contained in CIPSO category sets. This is still done were possible, but for labels that are too large a mapping is required. This is perfectly safe for communication that stays "on the box" and doesn't require much coordination between boxes beyond what would have been required to keep label names consistent. The bulk of this patch is in smackfs, adding and updating administrative interfaces. Because existing APIs can't be changed new ones that do much the same things as old ones have been introduced. The Smack specific CIPSO data representation has been removed and replaced with the data format used by netlabel. The CIPSO header is now computed when a label is imported rather than on use. This results in improved IP performance. The smack label is now allocated separately from the containing structure, allowing for larger strings. Four new /smack interfaces have been introduced as four of the old interfaces strictly required labels be specified in fixed length arrays. The access interface is supplemented with the check interface: access "Subject Object rwxat" access2 "Subject Object rwaxt" The load interface is supplemented with the rules interface: load "Subject Object rwxat" load2 "Subject Object rwaxt" The load-self interface is supplemented with the self-rules interface: load-self "Subject Object rwxat" load-self2 "Subject Object rwaxt" The cipso interface is supplemented with the wire interface: cipso "Subject lvl cnt c1 c2 ..." cipso2 "Subject lvl cnt c1 c2 ..." The old interfaces are maintained for compatibility. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2012-05-14Smack: recursive tramsmuteCasey Schaufler
The transmuting directory feature of Smack requires that the transmuting attribute be explicitly set in all cases. It seems the users of this facility would expect that the transmuting attribute be inherited by subdirectories that are created in a transmuting directory. This does not seem to add any additional complexity to the understanding of how the system works. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2012-04-09LSM: do not initialize common_audit_data to 0Eric Paris
It isn't needed. If you don't set the type of the data associated with that type it is a pretty obvious programming bug. So why waste the cycles? Signed-off-by: Eric Paris <eparis@redhat.com>
2012-04-03LSM: shrink the common_audit_data data unionEric Paris
After shrinking the common_audit_data stack usage for private LSM data I'm not going to shrink the data union. To do this I'm going to move anything larger than 2 void * ptrs to it's own structure and require it to be declared separately on the calling stack. Thus hot paths which don't need more than a couple pointer don't have to declare space to hold large unneeded structures. I could get this down to one void * by dealing with the key struct and the struct path. We'll see if that is helpful after taking care of networking. Signed-off-by: Eric Paris <eparis@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-04-03LSM: shrink sizeof LSM specific portion of common_audit_dataEric Paris
Linus found that the gigantic size of the common audit data caused a big perf hit on something as simple as running stat() in a loop. This patch requires LSMs to declare the LSM specific portion separately rather than doing it in a union. Thus each LSM can be responsible for shrinking their portion and don't have to pay a penalty just because other LSMs have a bigger space requirement. Signed-off-by: Eric Paris <eparis@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-20Smack: allow to access /smack/access as normal userJarkko Sakkinen
Allow query access as a normal user removing the need for CAP_MAC_ADMIN. Give RW access to /smack/access for UGO. Do not import smack labels in access check. Signed-off-by: Jarkko Sakkinen <jarkko.j.sakkinen@gmail.com> Signed-off-by: Casey Schaufler <cschaufler@cschaufler-intel.(none)>
2011-10-12Smack: Clean up commentsCasey Schaufler
There are a number of comments in the Smack code that are either malformed or include code. This patch cleans them up. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2011-10-12Smack: Rule list lookup performanceCasey Schaufler
This patch is targeted for the smack-next tree. Smack access checks suffer from two significant performance issues. In cases where there are large numbers of rules the search of the single list of rules is wasteful. Comparing the string values of the smack labels is less efficient than a numeric comparison would. These changes take advantage of the Smack label list, which maintains the mapping of Smack labels to secids and optional CIPSO labels. Because the labels are kept perpetually, an access check can be done strictly based on the address of the label in the list without ever looking at the label itself. Rather than keeping one global list of rules the rules with a particular subject label can be based off of that label list entry. The access check need never look at entries that do not use the current subject label. This requires that packets coming off the network with CIPSO direct Smack labels that have never been seen before be treated carefully. The only case where they could be delivered is where the receiving socket has an IPIN star label, so that case is explicitly addressed. On a system with 39,800 rules (200 labels in all permutations) a system with this patch runs an access speed test in 5% of the time of the old version. That should be a best case improvement. If all of the rules are associated with the same subject label and all of the accesses are for processes with that label (unlikely) the improvement is about 30%. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2011-04-25LSM: separate LSM_AUDIT_DATA_DENTRY from LSM_AUDIT_DATA_PATHEric Paris
This patch separates and audit message that only contains a dentry from one that contains a full path. This allows us to make it harder to misuse the interfaces or for the interfaces to be implemented wrong. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com>
2011-04-25LSM: split LSM_AUDIT_DATA_FS into _PATH and _INODEEric Paris
The lsm common audit code has wacky contortions making sure which pieces of information are set based on if it was given a path, dentry, or inode. Split this into path and inode to get rid of some of the code complexity. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com>
2011-02-09security:smack: kill unused SMACK_LIST_MAX, MAY_ANY and MAY_ANYWRITEShan Wei
Kill unused macros of SMACK_LIST_MAX, MAY_ANY and MAY_ANYWRITE. v2: As Casey Schaufler's advice, also remove MAY_ANY. Signed-off-by: Shan Wei <shanwei@cn.fujitsu.com> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2011-01-17Subject: [PATCH] Smack: mmap controls for library containmentCasey Schaufler
In the embedded world there are often situations where libraries are updated from a variety of sources, for a variety of reasons, and with any number of security characteristics. These differences might include privilege required for a given library provided interface to function properly, as occurs from time to time in graphics libraries. There are also cases where it is important to limit use of libraries based on the provider of the library and the security aware application may make choices based on that criteria. These issues are addressed by providing an additional Smack label that may optionally be assigned to an object, the SMACK64MMAP attribute. An mmap operation is allowed if there is no such attribute. If there is a SMACK64MMAP attribute the mmap is permitted only if a subject with that label has all of the access permitted a subject with the current task label. Security aware applications may from time to time wish to reduce their "privilege" to avoid accidental use of privilege. One case where this arises is the environment in which multiple sources provide libraries to perform the same functions. An application may know that it should eschew services made available from a particular vendor, or of a particular version. In support of this a secondary list of Smack rules has been added that is local to the task. This list is consulted only in the case where the global list has approved access. It can only further restrict access. Unlike the global last, if no entry is found on the local list access is granted. An application can add entries to its own list by writing to /smack/load-self. The changes appear large as they involve refactoring the list handling to accomodate there being more than one rule list. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2010-12-07Smack: Transmute labels on specified directoriesJarkko Sakkinen
In a situation where Smack access rules allow processes with multiple labels to write to a directory it is easy to get into a situation where the directory gets cluttered with files that the owner can't deal with because while they could be written to the directory a process at the label of the directory can't write them. This is generally the desired behavior, but when it isn't it is a real issue. This patch introduces a new attribute SMACK64TRANSMUTE that instructs Smack to create the file with the label of the directory under certain circumstances. A new access mode, "t" for transmute, is made available to Smack access rules, which are expanded from "rwxa" to "rwxat". If a file is created in a directory marked as transmutable and if access was granted to perform the operation by a rule that included the transmute mode, then the file gets the Smack label of the directory instead of the Smack label of the creating process. Note that this is equivalent to creating an empty file at the label of the directory and then having the other process write to it. The transmute scheme requires that both the access rule allows transmutation and that the directory be explicitly marked. Signed-off-by: Jarkko Sakkinen <ext-jarkko.2.sakkinen@nokia.com> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2010-12-02This patch adds a new security attribute to Smack calledCasey Schaufler
SMACK64EXEC. It defines label that is used while task is running. Exception: in smack_task_wait() child task is checked for write access to parent task using label inherited from the task that forked it. Fixed issues from previous submit: - SMACK64EXEC was not read when SMACK64 was not set. - inode security blob was not updated after setting SMACK64EXEC - inode security blob was not updated when removing SMACK64EXEC
2010-08-02security: move LSM xattrnames to xattr.hMimi Zohar
Make the security extended attributes names global. Updated to move the remaining Smack xattrs. Signed-off-by: Mimi Zohar <zohar@us.ibm.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
2009-07-10security: Make lsm_priv union in lsm_audit.h anonymousThomas Liu
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>
2009-07-10Move variable function in lsm_audit.h into SMACK private spaceThomas Liu
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>
2009-04-14smack: implement logging V3Etienne Basset
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>
2009-03-28smack: Add a new '-CIPSO' option to the network address label configurationEtienne Basset
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>
2009-03-28netlabel: Cleanup the Smack/NetLabel code to fix incoming TCP connectionsPaul Moore
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>
2009-03-26smack: convert smack to standard linux listsEtienne Basset
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>
2008-12-31smack: Add support for unlabeled network hosts and networksCasey Schaufler
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>
2008-08-05smack: limit privilege by labelCasey Schaufler
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>
2008-04-19Security: Introduce security= boot parameterAhmed S. Darwish
Add the security= boot parameter. This is done to avoid LSM registration clashes in case of more than one bult-in module. User can choose a security module to enable at boot. If no security= boot parameter is specified, only the first LSM asking for registration will be loaded. An invalid security module name will be treated as if no module has been chosen. LSM modules must check now if they are allowed to register by calling security_module_enable(ops) first. Modify SELinux and SMACK to do so. Do not let SMACK register smackfs if it was not chosen on boot. Smackfs assumes that smack hooks are registered and the initial task security setup (swapper->security) is done. Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> Acked-by: James Morris <jmorris@namei.org>
2008-03-13smackfs: do not trust `count' in inodes write()sAhmed S. Darwish
Smackfs write() implementation does not put a higher bound on the number of bytes to copy from user-space. This may lead to a DOS attack if a malicious `count' field is given. Assure that given `count' is exactly the length needed for a /smack/load rule. In case of /smack/cipso where the length is relative, assure that `count' does not exceed the size needed for a buffer representing maximum possible number of CIPSO 2.2 categories. Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05Smack: Simplified Mandatory Access Control KernelCasey Schaufler
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>