Version 9 (2.6.24-rc1) Smack: Simplified Mandatory Access Control Kernel

From: Casey Schaufler <[email protected]>

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

This version has been tested with 2.6.23, various 2.6.23-gits and 2.6.24-rc1. 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 accomodate 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 <[email protected]>

---

This patch depends on the netlabel interface patch by Paul Moore <[email protected]> in support of a more comfortable interface to initialize the CIPSO code from within the kernel. This patch was titled "[NetLabel] Introduce a new kernel configuration API for NetLabel".

This version is again aimed at addressing Al Viro's issues in smackfs. Ahmed Darwish has again contributed in the repair of the locking issues there. The move to 2.6.24 was also an important release incentive.

Thank you.

 Documentation/Smack.txt       |  483 +++++
 security/Kconfig              |    1 
 security/Makefile             |    2 
 security/smack/Kconfig        |   10 
 security/smack/Makefile       |    7 
 security/smack/smack.h        |  222 ++
 security/smack/smack_access.c |  353 ++++
 security/smack/smack_lsm.c    | 2664 ++++++++++++++++++++++++++++++++
 security/smack/smackfs.c      |  929 +++++++++++
 9 files changed, 4671 insertions(+)

diff -uprN -X linux-2.6.24-rc1-base/Documentation/dontdiff linux-2.6.24-rc1-base/Documentation/Smack.txt linux-2.6.24-rc1-smack/Documentation/Smack.txt

Documentation/Smack.txt +5 -0

@@ -0,0 +1,483 @@
+
+
+    "Good for you, you've decided to clean the elevator!"
+    - The Elevator, from Dark Star
+

diff -uprN -X linux-2.6.24-rc1-base/Documentation/dontdiff linux-2.6.24-rc1-base/security/smack/smack_lsm.c linux-2.6.24-rc1-smack/security/smack/smack_lsm.c

security/smack/smack_lsm.c +27 -0

@@ -0,0 +1,2664 @@
+/*
+ *  Simplified MAC Kernel (smack) security module
+ *
+ *  This file contains the smack hook function implementations.
+ *
+ *  Author:
+ *	Casey Schaufler <[email protected]>
+ *
+ *  Copyright (C) 2007 Casey Schaufler <[email protected]>
+ *
+ *	This program is free software; you can redistribute it and/or modify
+ *	it under the terms of the GNU General Public License version 2,
+ *      as published by the Free Software Foundation.
+ */
+
+#include <linux/xattr.h>
+#include <linux/pagemap.h>
+#include <linux/mount.h>
+#include <linux/stat.h>
+#include <linux/ext2_fs.h>
+#include <linux/kd.h>
+#include <asm/ioctls.h>
+#include <linux/tcp.h>
+#include <linux/udp.h>
+#include <linux/mutex.h>
+#include <net/netlabel.h>
+#include <net/cipso_ipv4.h>

security/smack/smack_lsm.c +18 -0

+/**
+ * smack_task_kill - Samck check on signal delivery
+ * @p: the task object
+ * @info: unused
+ * @sig: unused
+ * @secid: identifies the smack to use in lieu of current's
+ *
+ * Return 0 if write access is permitted
+ *
+ * The secid behavior is an artifact of an SELinux hack
+ * in the USB code. Someday it may go away.
+ */
+static int smack_task_kill(struct task_struct *p, struct siginfo *info,
+			   int sig, u32 secid)
+{
+	/*
+	 * Sending a signal requires that the sender
+	 * can write the receiver.

security/smack/smack_lsm.c +9 -0

+/**
+ * smack_sb_kern_mount - Smack specific mount processing
+ * @sb: the file system superblock
+ * @data: the smack mount options
+ *
+ * Returns 0 on success, an error code on failure
+ */
+static int smack_sb_kern_mount(struct super_block *sb, void *data)
+{

security/smack/smack_lsm.c +45 -0

+
+	for (op = data; op != NULL; op = commap) {
+		commap = strchr(op, ',');
+		if (commap != NULL)
+			*commap++ = '\0';
+
+		if (strncmp(op, SMK_FSHAT, strlen(SMK_FSHAT)) == 0) {
+			op += strlen(SMK_FSHAT);
+			nsp = smk_import(op, 0);
+			if (nsp != NULL)
+				sp->smk_hat = nsp;
+		} else if (strncmp(op, SMK_FSFLOOR, strlen(SMK_FSFLOOR)) == 0) {
+			op += strlen(SMK_FSFLOOR);
+			nsp = smk_import(op, 0);
+			if (nsp != NULL)
+				sp->smk_floor = nsp;
+		} else if (strncmp(op, SMK_FSDEFAULT,
+				   strlen(SMK_FSDEFAULT)) == 0) {
+			op += strlen(SMK_FSDEFAULT);
+			nsp = smk_import(op, 0);
+			if (nsp != NULL)
+				sp->smk_default = nsp;
+		} else if (strncmp(op, SMK_FSROOT, strlen(SMK_FSROOT)) == 0) {
+			op += strlen(SMK_FSROOT);
+			nsp = smk_import(op, 0);
+			if (nsp != NULL)
+				sp->smk_root = nsp;
+		}
+	}
+
+	/*
+	 * Initialize the root inode.
+	 */
+	isp = inode->i_security;
+	if (isp == NULL)
+		inode->i_security = new_inode_smack(sp->smk_root);
+	else
+		isp->smk_inode = sp->smk_root;
+
+	return 0;
+}
+
+/**
+ * smack_sb_statfs - Smack check on statfs
+ * @dentry: identifies the file system in question

security/smack/smack_lsm.c +16 -0

+		return 0;
+
+	sbp = dentry->d_sb->s_security;
+
+	return smk_curacc(sbp->smk_floor, MAY_READ);
+}
+
+/**
+ * smack_sb_mount - Smack check for mounting
+ * @dev_name: unused
+ * @nd: mount point
+ * @type: unused
+ * @flags: unused
+ * @data: unused
+ *
+ * Returns 0 if current can write the floor of the filesystem

security/smack/smack_lsm.c +89 -0

+
+	sbp = nd->mnt->mnt_sb->s_security;
+
+	return smk_curacc(sbp->smk_floor, MAY_WRITE);
+}
+
+/**
+ * smack_sb_umount - Smack check for unmounting
+ * @mnt: file system to unmount
+ * @flags: unused
+ *
+ * Returns 0 if current can write the floor of the filesystem
+ * being unmounted, an error code otherwise.
+ */
+static int smack_sb_umount(struct vfsmount *mnt, int flags)
+{
+	struct superblock_smack *sbp;
+
+	sbp = mnt->mnt_sb->s_security;
+
+	return smk_curacc(sbp->smk_floor, MAY_WRITE);
+}
+
+/*
+ * Inode hooks
+ */
+
+/**
+ * smack_inode_alloc_security - allocate an inode blob
+ * @inode - the inode in need of a blob
+ *
+ * Returns 0 if it gets a blob, -ENOMEM otherwise
+ */
+static int smack_inode_alloc_security(struct inode *inode)
+{
+	inode->i_security = new_inode_smack(current->security);
+	if (inode->i_security == NULL)
+		return -ENOMEM;
+	return 0;
+}
+
+/**
+ * smack_inode_free_security - free an inode blob
+ * @inode - the inode with a blob
+ *
+ * Clears the blob pointer in inode
+ */
+static void smack_inode_free_security(struct inode *inode)
+{
+	kfree(inode->i_security);
+	inode->i_security = NULL;
+}
+
+/**
+ * smack_inode_init_security - copy out the smack from an inode
+ * @inode: the inode
+ * @dir: unused
+ * @name: where to put the attribute name
+ * @value: where to put the attribute value
+ * @len: where to put the length of the attribute
+ *
+ * Returns 0 if it all works out, -ENOMEM if there's no memory
+ */
+static int smack_inode_init_security(struct inode *inode, struct inode *dir,
+				     char **name, void **value, size_t *len)
+{
+	char *isp = smk_of_inode(inode);
+
+	if (name) {
+		*name = kstrdup(XATTR_SMACK_SUFFIX, GFP_KERNEL);
+		if (*name == NULL)
+			return -ENOMEM;
+	}
+
+	if (value) {
+		*value = kstrdup(isp, GFP_KERNEL);
+		if (*value == NULL)
+			return -ENOMEM;
+	}
+
+	if (len)
+		*len = strlen(isp) + 1;
+
+	return 0;
+}
+
+/**
+ * smack_inode_link - Smack check on link
+ * @old_dentry: unused

security/smack/smack_lsm.c +4 -0

+
+/**
+ * smack_inode_symlink - Smack check on symlink
+ * @dir: the directory to add the entry to

security/smack/smack_lsm.c +5 -0

+
+/**
+ * smack_inode_mknod - Smack check on mknod
+ * @dir: the directory to add the entry to
+ * @dentry: unused

security/smack/smack_lsm.c +15 -0

+
+/**
+ * smack_inode_rename - Smack check on rename
+ * @old_inode: the old directory
+ * @old_dentry: unused
+ * @new_inode: the new directory
+ * @new_dentry: unused
+ *
+ * Read and write access is required on both the old and
+ * new directories.
+ *
+ * Returns 0 if access is permitted, an error code otherwise
+ */
+static int smack_inode_rename(struct inode *old_inode,
+			      struct dentry *old_dentry,

security/smack/smack_lsm.c +46 -0

+
+/**
+ * smack_inode_readlink - Smack check on readlink
+ * @dentry: the symlink
+ *
+ * Returns 0 if access is permitted, an error code otherwise
+ */
+static int smack_inode_readlink(struct dentry *dentry)
+{
+	return smk_curacc(smk_of_inode(dentry->d_inode), MAY_READ);
+}
+
+/**
+ * smack_inode_follow_link - Smack check on following a symlink
+ * @dentry: the symlink
+ * @nameidata: unused
+ *
+ * Returns 0 if access is permitted, an error code otherwise
+ */
+static int smack_inode_follow_link(struct dentry *dentry,
+				   struct nameidata *nameidata)
+{
+	return smk_curacc(smk_of_inode(dentry->d_inode), MAY_READ);
+}
+
+/**
+ * smack_inode_permission - Smack version of permission()
+ * @inode: the inode in question
+ * @mask: the access requested
+ * @nd: unused
+ *
+ * Returns 0 if access is permitted, an error code otherwise
+ */
+static int smack_inode_permission(struct inode *inode, int mask,
+				  struct nameidata *nd)
+{
+	/*
+	 * No permission to check. Existence test. Yup, it's there.
+	 */
+	if (mask == 0)
+		return 0;
+
+	return smk_curacc(smk_of_inode(inode), mask);
+}
+
+/**

security/smack/smack_lsm.c +26 -0

+
+/**
+ * smack_inode_getattr - Smack check for getting attributes
+ * @mnt: unused
+ * @dentry: the object
+ *
+ * Returns 0 if access is permitted, an error code otherwise
+ */
+static int smack_inode_getattr(struct vfsmount *mnt, struct dentry *dentry)
+{
+	return smk_curacc(smk_of_inode(dentry->d_inode), MAY_READ);
+}
+
+/**
+ * smack_inode_setxattr - Smack check for setting xattrs
+ * @dentry: the object
+ * @name: passed to the cap call
+ * @value: passed to the cap call
+ * @size: passed to the cap call
+ * @flags: passed to the cap call
+ *
+ * Check with cap_inode_setxattr to see if the capability
+ * scheme approves, then check the Smack access
+ *
+ * Returns 0 if access is permitted, an error code otherwise
+ */

security/smack/smack_lsm.c +78 -0

+	if (rc == 0)
+		rc = smk_curacc(smk_of_inode(dentry->d_inode), MAY_WRITE);
+
+	return rc;
+}
+
+/**
+ * smack_inode_post_setxattr - Apply the Smack update approved above
+ * @dentry: object
+ * @name: attribute name
+ * @value: attribute value
+ * @size: attribute size
+ * @flags: unused
+ *
+ * Set the pointer in the inode blob to the entry found
+ * in the master label list.
+ */
+static void smack_inode_post_setxattr(struct dentry *dentry, char *name,
+				      void *value, size_t size, int flags)
+{
+	struct inode_smack *isp;
+	char *nsp;
+
+	/*
+	 * Not SMACK
+	 */
+	if (strcmp(name, XATTR_NAME_SMACK))
+		return;
+
+	if (size >= SMK_LABELLEN)
+		return;
+
+	isp = dentry->d_inode->i_security;
+
+	/*
+	 * No locking is done here. This is a pointer
+	 * assignment.
+	 */
+	nsp = smk_import(value, size);
+	if (nsp != NULL)
+		isp->smk_inode = nsp;
+	else
+		isp->smk_inode = smack_known_invalid.smk_known;
+
+	return;
+}
+
+/*
+ * smack_inode_getxattr - Smack check on getxattr
+ * @dentry: the object
+ * @name: unused
+ *
+ * Returns 0 if access is permitted, an error code otherwise
+ */
+static int smack_inode_getxattr(struct dentry *dentry, char *name)
+{
+	return smk_curacc(smk_of_inode(dentry->d_inode), MAY_READ);
+}
+
+/*
+ * smack_inode_listxattr - Smack check on listxattr
+ * @dentry: the object
+ *
+ * Returns 0 if access is permitted, an error code otherwise
+ */
+static int smack_inode_listxattr(struct dentry *dentry)
+{
+	return smk_curacc(smk_of_inode(dentry->d_inode), MAY_READ);
+}
+
+/*
+ * smack_inode_removexattr - Smack check on removexattr
+ * @dentry: the object
+ * @name: name of the attribute
+ *
+ * Removing the Smack attribute requires CAP_MAC_OVERRIDE
+ *
+ * Returns 0 if access is permitted, an error code otherwise

security/smack/smack_lsm.c +20 -0

+	if (rc == 0)
+		rc = smk_curacc(smk_of_inode(dentry->d_inode), MAY_WRITE);
+
+	return rc;
+}
+
+/**
+ * smack_inode_getsecurity - get smack xattrs
+ * @inode: the object
+ * @name: attribute name
+ * @buffer: where to put the result
+ * @size: size of the buffer
+ * @err: unused
+ *
+ * Returns the size of the attribute or an error code
+ */
+static int smack_inode_getsecurity(const struct inode *inode,
+				   const char *name, void *buffer,
+				   size_t size, int err)
+{

security/smack/smack_lsm.c +129 -0

+
+	if (strcmp(name, XATTR_SMACK_SUFFIX) == 0) {
+		isp = smk_of_inode(inode);
+		strncpy(buffer, isp, SMK_LABELLEN);
+		return strlen(isp) + 1;
+	}
+
+	/*
+	 * The rest of the Smack xattrs are only on sockets.
+	 */
+	sbp = ip->i_sb;
+	if (sbp->s_magic != SOCKFS_MAGIC)
+		return -EOPNOTSUPP;
+
+	sock = SOCKET_I(ip);
+	if (sock == NULL)
+		return -EOPNOTSUPP;
+
+	ssp = sock->sk->sk_security;
+
+	/*
+	 * Should the packet attribute be unavailable return the error.
+	 * This can happen if packets come in too fast.
+	 */
+	if (strcmp(name, XATTR_SMACK_PACKET) == 0) {
+		if (ssp->smk_packet[0] == '\0')
+			return -ENODATA;
+		isp = ssp->smk_packet;
+	} else if (strcmp(name, XATTR_SMACK_IPIN) == 0)
+		isp = ssp->smk_in;
+	else if (strcmp(name, XATTR_SMACK_IPOUT) == 0)
+		isp = ssp->smk_out;
+	else
+		return -EOPNOTSUPP;
+
+	strncpy(buffer, isp, SMK_LABELLEN);
+	return strlen(isp) + 1;
+}
+
+/**
+ * smack_inode_setsecurity - set smack xattrs
+ * @inode: the object
+ * @name: attribute name
+ * @value: attribute value
+ * @size: size of the attribute
+ * @flags: unused
+ *
+ * Sets the named attribute in the appropriate blob
+ *
+ * Returns 0 on success, or an error code
+ */
+static int smack_inode_setsecurity(struct inode *inode, const char *name,
+				   const void *value, size_t size, int flags)
+{
+	char *sp;
+	struct inode_smack *nsp = (struct inode_smack *)inode->i_security;
+	struct socket_smack *ssp;
+	struct socket *sock;
+
+	if (value == NULL || size > SMK_LABELLEN)
+		return -EACCES;
+
+	sp = smk_import(value, size);
+	if (sp == NULL)
+		return -EINVAL;
+
+	if (strcmp(name, XATTR_SMACK_SUFFIX) == 0) {
+		mutex_lock(&nsp->smk_lock);
+		nsp->smk_inode = sp;
+		mutex_unlock(&nsp->smk_lock);
+		return 0;
+	}
+	/*
+	 * The rest of the Smack xattrs are only on sockets.
+	 */
+	if (inode->i_sb->s_magic != SOCKFS_MAGIC)
+		return -EOPNOTSUPP;
+
+	sock = SOCKET_I(inode);
+	if (sock == NULL)
+		return -EOPNOTSUPP;
+
+	ssp = sock->sk->sk_security;
+
+	if (strcmp(name, XATTR_SMACK_PACKET) == 0) {
+		memset(ssp->smk_packet, '\0', SMK_LABELLEN);
+		strncpy(ssp->smk_packet, sp, SMK_LABELLEN);
+	} else if (strcmp(name, XATTR_SMACK_IPIN) == 0)
+		ssp->smk_in = sp;
+	else if (strcmp(name, XATTR_SMACK_IPOUT) == 0)
+		ssp->smk_out = sp;
+	else
+		return -EOPNOTSUPP;
+	return 0;
+}
+
+/**
+ * smack_inode_listsecurity - list the Smack attributes
+ * @inode: the object
+ * @buffer: where they go
+ * @buffer_size: size of buffer
+ *
+ * Returns 0 on success, -EINVAL otherwise
+ */
+static int smack_inode_listsecurity(struct inode *inode, char *buffer,
+				    size_t buffer_size)
+{
+	int len = strlen(XATTR_NAME_SMACK);
+
+	if (buffer != NULL && len <= buffer_size) {
+		memcpy(buffer, XATTR_NAME_SMACK, len);
+		return len;
+	}
+	return -EINVAL;
+}
+
+/**
+ * smack_d_instantiate - Make sure the blob is correct on an inode
+ * @opt_dentry: unused
+ * @inode: the object
+ *
+ * Set the inode's security blob if it hasn't been done already.
+ */
+static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
+{
+	struct super_block *sbp;
+	struct superblock_smack *sbsp;
+	struct inode_smack *isp;
+	char *csp = current->security;

security/smack/smack_lsm.c +438 -0

+
+	isp = inode->i_security;
+
+	mutex_lock(&isp->smk_lock);
+	/*
+	 * If the inode is already instantiated
+	 * take the quick way out
+	 */
+	if (isp->smk_flags & SMK_INODE_INSTANT)
+		goto unlockandout;
+
+	sbp = inode->i_sb;
+	sbsp = sbp->s_security;
+	/*
+	 * We're going to use the superblock default label
+	 * if there's no label on the file.
+	 */
+	final = sbsp->smk_default;
+
+	/*
+	 * This is pretty hackish.
+	 * Casey says that we shouldn't have to do
+	 * file system specific code, but it does help
+	 * with keeping it simple.
+	 */
+	switch (sbp->s_magic) {
+	case SMACK_MAGIC:
+		/*
+		 * Casey says that it's a little embarassing
+		 * that the smack file system doesn't do
+		 * extended attributes.
+		 */
+		final = smack_known_star.smk_known;
+		break;
+	case PIPEFS_MAGIC:
+		/*
+		 * Casey says pipes are easy (?)
+		 */
+		final = smack_known_star.smk_known;
+		break;
+	case DEVPTS_SUPER_MAGIC:
+		/*
+		 * devpts seems content with the label of the task.
+		 * Programs that change smack have to treat the
+		 * pty with respect.
+		 */
+		final = csp;
+		break;
+	case SOCKFS_MAGIC:
+		/*
+		 * Casey says sockets get the smack of the task.
+		 */
+		final = csp;
+		break;
+	case PROC_SUPER_MAGIC:
+		/*
+		 * Casey says procfs appears not to care.
+		 * The superblock default suffices.
+		 */
+		break;
+	case TMPFS_MAGIC:
+		/*
+		 * Device labels should come from the filesystem,
+		 * but watch out, because they're volitile,
+		 * getting recreated on every reboot.
+		 */
+		final = smack_known_star.smk_known;
+		/*
+		 * No break.
+		 *
+		 * If a smack value has been set we want to use it,
+		 * but since tmpfs isn't giving us the opportunity
+		 * to set mount options simulate setting the
+		 * superblock default.
+		 */
+	default:
+		/*
+		 * This isn't an understood special case.
+		 * Get the value from the xattr.
+		 *
+		 * No xattr support means, alas, no SMACK label.
+		 * Use the aforeapplied default.
+		 * It would be curious if the label of the task
+		 * does not match that assigned.
+		 */
+		if (inode->i_op->getxattr == NULL)
+			break;
+		/*
+		 * Get the dentry for xattr.
+		 */
+		if (opt_dentry == NULL) {
+			dp = d_find_alias(inode);
+			if (dp == NULL)
+				break;
+		} else {
+			dp = dget(opt_dentry);
+			if (dp == NULL)
+				break;
+		}
+
+		fetched = smk_fetch(inode, dp);
+		if (fetched != NULL)
+			final = fetched;
+
+		dput(dp);
+		break;
+	}
+
+	if (final == NULL)
+		isp->smk_inode = csp;
+	else
+		isp->smk_inode = final;
+
+	isp->smk_flags |= SMK_INODE_INSTANT;
+
+unlockandout:
+	mutex_unlock(&isp->smk_lock);
+	return;
+}
+
+/*
+ * File Hooks
+ */
+
+/**
+ * smack_file_alloc_security - assign a file security blob
+ * @file: the object
+ *
+ * The security blob for a file is a pointer to the master
+ * label list, so no allocation is done.
+ *
+ * Returns 0
+ */
+static int smack_file_alloc_security(struct file *file)
+{
+	file->f_security = current->security;
+	return 0;
+}
+
+/**
+ * smack_file_free_security - clear a file security blob
+ * @file: the object
+ *
+ * The security blob for a file is a pointer to the master
+ * label list, so no memory is freed.
+ */
+static void smack_file_free_security(struct file *file)
+{
+	file->f_security = NULL;
+}
+
+/**
+ * smack_file_permission - Smack check on file operations
+ * @file: unused
+ * @mask: unused
+ *
+ * Returns 0
+ *
+ * Should access checks be done on each read or write?
+ * UNICOS and SELinux say yes.
+ * Trusted Solaris, Trusted Irix, and just about everyone else says no.
+ *
+ * I'll say no for now. Smack does not do the frequent
+ * label changing that SELinux does.
+ */
+static int smack_file_permission(struct file *file, int mask)
+{
+	return 0;
+}
+
+/**
+ * smack_file_ioctl - Smack check on ioctls
+ * @file: the object
+ * @cmd: what to do
+ * @arg: unused
+ *
+ * Relies heavily on the correct use of the ioctl command conventions.
+ *
+ * Returns 0 if allowed, error code otherwise
+ */
+static int smack_file_ioctl(struct file *file, unsigned int cmd,
+			    unsigned long arg)
+{
+	int rc = 0;
+
+	if (_IOC_DIR(cmd) & _IOC_WRITE)
+		rc = smk_curacc(file->f_security, MAY_WRITE);
+
+	if (rc == 0 && (_IOC_DIR(cmd) & _IOC_READ))
+		rc = smk_curacc(file->f_security, MAY_READ);
+
+	return rc;
+}
+
+/**
+ * smack_file_lock - Smack check on file locking
+ * @file: the object
+ * @cmd unused
+ *
+ * Returns 0 if current has write access, error code otherwise
+ */
+static int smack_file_lock(struct file *file, unsigned int cmd)
+{
+	return smk_curacc(file->f_security, MAY_WRITE);
+}
+
+/**
+ * smack_file_fcntl - Smack check on fcntl
+ * @file: the object
+ * @cmd: what action to check
+ * @arg: unused
+ *
+ * Returns 0 if current has access, error code otherwise
+ */
+static int smack_file_fcntl(struct file *file, unsigned int cmd,
+			    unsigned long arg)
+{
+	int rc;
+
+	switch (cmd) {
+	case F_DUPFD:
+	case F_GETFD:
+	case F_GETFL:
+	case F_GETLK:
+	case F_GETOWN:
+	case F_GETSIG:
+		rc = smk_curacc(file->f_security, MAY_READ);
+		break;
+	case F_SETFD:
+	case F_SETFL:
+	case F_SETLK:
+	case F_SETLKW:
+	case F_SETOWN:
+	case F_SETSIG:
+		rc = smk_curacc(file->f_security, MAY_WRITE);
+		break;
+	default:
+		rc = smk_curacc(file->f_security, MAY_READWRITE);
+	}
+
+	return rc;
+}
+
+/**
+ * smack_file_send_sigiotask - Smack on sigio
+ * @tsk: The target task
+ * @fown: the object the signal come from
+ * @signum: unused
+ *
+ * Allow a privileged task to get signals even if it shouldn't
+ *
+ * Returns 0 if a subject with the object's smack could
+ * write to the task, an error code otherwise.
+ */
+static int smack_file_send_sigiotask(struct task_struct *tsk,
+				     struct fown_struct *fown, int signum)
+{
+	struct file *file;
+	int rc;
+
+	/*
+	 * struct fown_struct is never outside the context of a struct file
+	 */
+	file = (struct file *)((long)fown - offsetof(struct file, f_owner));
+	rc = smk_access(file->f_security, tsk->security, MAY_WRITE);
+	if (rc != 0 && __capable(tsk, CAP_MAC_OVERRIDE))
+		return 0;
+	return rc;
+}
+
+/**
+ * smack_file_receive - Smack file receive check
+ * @file: the object
+ *
+ * Returns 0 if current has access, error code otherwise
+ */
+static int smack_file_receive(struct file *file)
+{
+	int may = 0;
+
+	/*
+	 * This code relies on bitmasks.
+	 */
+	if (file->f_mode & FMODE_READ)
+		may = MAY_READ;
+	if (file->f_mode & FMODE_WRITE)
+		may |= MAY_WRITE;
+
+	return smk_curacc(file->f_security, may);
+}
+
+/*
+ * Socket hooks.
+ */
+
+/**
+ * smack_sk_alloc_security - Allocate a socket blob
+ * @sk: the socket
+ * @family: unused
+ * @priority: memory allocation priority
+ *
+ * Assign Smack pointers to current except for smk_packet which
+ * is not a pointer but the real thing.
+ *
+ * Returns 0 on success, -ENOMEM is there's no memory
+ */
+static int smack_sk_alloc_security(struct sock *sk, int family, gfp_t priority)
+{
+	char *csp = current->security;
+	struct socket_smack *ssp;
+
+	ssp = kzalloc(sizeof(struct socket_smack), priority);
+	if (ssp == NULL)
+		return -ENOMEM;
+
+	ssp->smk_in = csp;
+	ssp->smk_out = csp;
+	memset(ssp->smk_packet, '\0', SMK_LABELLEN);
+	strcpy(ssp->smk_packet, smack_known_invalid.smk_known);
+	ssp->smk_depth = 0;
+
+	sk->sk_security = ssp;
+
+	return 0;
+}
+
+/**
+ * smack_sk_free_security - Free a socket blob
+ * @sk: the socket
+ *
+ * Clears the blob pointer
+ */
+static void smack_sk_free_security(struct sock *sk)
+{
+	kfree(sk->sk_security);
+	sk->sk_security = NULL;
+}
+
+/**
+ * smack_set_catset - convert a capset to netlabel mls categories
+ * @catset: the Smack categories
+ * @sap: where to put the netlabel categories
+ *
+ * Allocates and fills mls_cat
+ */
+static void smack_set_catset(char *catset, struct netlbl_lsm_secattr *sap)
+{
+	unsigned char *cp;
+	unsigned char m;
+	int cat;
+	int rc;
+
+	if (catset == 0)
+		return;
+
+	sap->flags |= NETLBL_SECATTR_MLS_CAT;
+	sap->mls_cat = netlbl_secattr_catmap_alloc(GFP_ATOMIC);
+	sap->mls_cat->startbit = 0;
+
+	for (cat = 1, cp = catset; *cp != 0; cp++)
+		for (m = 0x80; m != 0; m >>= 1, cat++) {
+			if ((m & *cp) == 0)
+				continue;
+			rc = netlbl_secattr_catmap_setbit(sap->mls_cat, cat,
+							  GFP_ATOMIC);
+		}
+}
+
+/**
+ * smack_to_secattr - fill a secattr from a smack value
+ * @smack: the smack value
+ * @nlsp: where the result goes
+ *
+ * Casey says that CIPSO is good enough for now.
+ * It can be used to effect.
+ * It can also be abused to effect when necessary.
+ * Appologies to the TSIG group in general and GW in particular.
+ */
+static void smack_to_secattr(char *smack, struct netlbl_lsm_secattr *nlsp)
+{
+	struct smack_cipso cipso;
+	int rc;
+
+	switch (smack_net_nltype) {
+	case NETLBL_NLTYPE_CIPSOV4:
+		nlsp->domain = NULL;
+		nlsp->flags = NETLBL_SECATTR_DOMAIN;
+		nlsp->flags |= NETLBL_SECATTR_MLS_LVL;
+
+		rc = smack_to_cipso(smack, &cipso);
+		if (rc == 0) {
+			nlsp->mls_lvl = cipso.smk_level;
+			smack_set_catset(cipso.smk_catset, nlsp);
+		} else {
+			nlsp->mls_lvl = smack_cipso_direct;
+			smack_set_catset(smack, nlsp);
+		}
+		break;
+	default:
+		break;
+	}
+}
+
+/**
+ * smack_netlabel - Set the secattr on a socket
+ * @sk: the socket
+ *
+ * Convert the outbound smack value (smk_out) to a
+ * secattr and attach it to the socket.
+ *
+ * Returns 0 on success or an error code
+ */
+static int smack_netlabel(struct sock *sk)
+{
+	struct socket_smack *ssp = sk->sk_security;
+	struct netlbl_lsm_secattr secattr;
+	int rc = 0;
+
+	netlbl_secattr_init(&secattr);
+	smack_to_secattr(ssp->smk_out, &secattr);
+	if (secattr.flags != NETLBL_SECATTR_NONE)
+		rc = netlbl_sock_setattr(sk, &secattr);
+
+	netlbl_secattr_destroy(&secattr);
+	return rc;
+}
+
+/**
+ * smack_socket_post_create - finish socket setup
+ * @sock: the socket
+ * @family: protocol family
+ * @type: unused
+ * @protocol: unused
+ * @kern: indicates kern vs task socket
+ *
+ * Sets the security blob on the socket's inode.
+ * Sets the secattr value for outgoing packets.
+ *

security/smack/smack_lsm.c +20 -0

+		if (kern)
+			isp = new_inode_smack(smack_known_floor.smk_known);
+		else
+			isp = new_inode_smack(current->security);
+		SOCK_INODE(sock)->i_security = isp;
+	}
+
+	if (family != PF_INET)
+		return 0;
+
+	/*
+	 * Set the outbound netlbl.
+	 */
+	return smack_netlabel(sock->sk);
+}
+
+/**
+ * smack_inode_create - Smack check on inode creation
+ * @dir: containing directory object
+ * @dentry: unused

security/smack/smack_lsm.c +30 -0

+
+/**
+ * smack_inode_unlink - Smack check on inode deletion
+ * @dir: containing directory object
+ * @dentry: file to unlink
+ *
+ * Returns 0 if current can write the containing directory
+ * and the object, error code otherwise
+ */
+static int smack_inode_unlink(struct inode *dir, struct dentry *dentry)
+{
+	struct inode *ip = dentry->d_inode;
+	int rc;
+
+	/*
+	 * You need write access to the thing you're unlinking
+	 */
+	rc = smk_curacc(smk_of_inode(ip), MAY_WRITE);
+	if (rc == 0)
+		/*
+		 * You also need write access to the containing directory
+		 */
+		rc = smk_curacc(smk_of_inode(dir), MAY_WRITE);
+
+	return rc;
+}
+
+/**
+ * smack_inode_mkdir - Smack check on directory creation
+ * @dir: containing directory object

security/smack/smack_lsm.c +162 -0

+
+/**
+ * smack_inode_rmdir - Smack check on directory deletion
+ * @dir: containing directory object
+ * @dentry: directory to unlink
+ *
+ * Returns 0 if current can write the containing directory
+ * and the directory, error code otherwise
+ */
+static int smack_inode_rmdir(struct inode *dir, struct dentry *dentry)
+{
+	struct inode *ip = dentry->d_inode;
+	int rc;
+
+	/*
+	 * You need write access to the thing you're removing
+	 */
+	rc = smk_curacc(smk_of_inode(ip), MAY_WRITE);
+	if (rc == 0)
+		/*
+		 * You also need write access to the containing directory
+		 */
+		rc = smk_curacc(smk_of_inode(dir), MAY_WRITE);
+
+	return rc;
+}
+
+/**
+ * smack_file_set_fowner - set the file security blob value
+ * @file: object in question
+ *
+ * Returns 0
+ * Further research may be required on this one.
+ */
+static int smack_file_set_fowner(struct file *file)
+{
+	file->f_security = current->security;
+	return 0;
+}
+
+/**
+ * smack_task_getpgid - Smack access check for getpgid
+ * @p: the object task
+ *
+ * Returns 0 if current can read the object task, error code otherwise
+ */
+static int smack_task_getpgid(struct task_struct *p)
+{
+	return smk_curacc(p->security, MAY_READ);
+}
+
+/**
+ * smack_task_getsid - Smack access check for getsid
+ * @p: the object task
+ *
+ * Returns 0 if current can read the object task, error code otherwise
+ */
+static int smack_task_getsid(struct task_struct *p)
+{
+	return smk_curacc(p->security, MAY_READ);
+}
+
+/**
+ * smack_task_getsecid - get the secid of the task
+ * @p: the object task
+ * @secid: where to put the result
+ *
+ * Sets the secid to contain a u32 version of the smack label.
+ */
+static void smack_task_getsecid(struct task_struct *p, u32 *secid)
+{
+	*secid = smack_to_secid(p->security);
+}
+
+/**
+ * smack_flags_to_may - convert S_ to MAY_ values
+ * @flags: the S_ value
+ *
+ * Returns the equivalent MAY_ value
+ */
+static int smack_flags_to_may(int flags)
+{
+	int may = 0;
+
+	if (flags & S_IRUGO)
+		may |= MAY_READ;
+	if (flags & S_IWUGO)
+		may |= MAY_WRITE;
+	if (flags & S_IXUGO)
+		may |= MAY_EXEC;
+
+	return may;
+}
+
+/**
+ * smack_msg_msg_alloc_security - Set the security blob for msg_msg
+ * @msg: the object
+ *
+ * Returns 0
+ */
+static int smack_msg_msg_alloc_security(struct msg_msg *msg)
+{
+	msg->security = current->security;
+	return 0;
+}
+
+/**
+ * smack_msg_msg_free_security - Clear the security blob for msg_msg
+ * @msg: the object
+ *
+ * Clears the blob pointer
+ */
+static void smack_msg_msg_free_security(struct msg_msg *msg)
+{
+	msg->security = NULL;
+}
+
+/**
+ * smack_of_shm - the smack pointer for the shm
+ * @shp: the object
+ *
+ * Returns a pointer to the smack value
+ */
+static char *smack_of_shm(struct shmid_kernel *shp)
+{
+	if (shp == NULL)
+		return NULL;
+
+	return (char *)shp->shm_perm.security;
+}
+
+/**
+ * smack_shm_alloc_security - Set the security blob for shm
+ * @shp: the object
+ *
+ * Returns 0
+ */
+static int smack_shm_alloc_security(struct shmid_kernel *shp)
+{
+	struct kern_ipc_perm *isp = &shp->shm_perm;
+
+	isp->security = current->security;
+	return 0;
+}
+
+/**
+ * smack_shm_free_security - Clear the security blob for shm
+ * @shp: the object
+ *
+ * Clears the blob pointer
+ */
+static void smack_shm_free_security(struct shmid_kernel *shp)
+{
+	struct kern_ipc_perm *isp = &shp->shm_perm;
+
+	isp->security = NULL;
+}
+
+/**
+ * smack_shm_associate - Smack access check for shm
+ * @shp: the object
+ * @shmflg: access requested

security/smack/smack_lsm.c +9 -0

+
+	may = smack_flags_to_may(shmflg);
+	return smk_curacc(ssp, may);
+}
+
+/**
+ * smack_shm_shmctl - Smack access check for shm
+ * @shp: the object
+ * @cmd: what it wants to do

security/smack/smack_lsm.c +31 -0

+
+	switch (cmd) {
+	case IPC_STAT:
+	case SHM_STAT:
+		may = MAY_READ;
+		break;
+	case IPC_SET:
+	case SHM_LOCK:
+	case SHM_UNLOCK:
+	case IPC_RMID:
+		may = MAY_READWRITE;
+		break;
+	case IPC_INFO:
+	case SHM_INFO:
+		/*
+		 * System level information.
+		 */
+		return 0;
+	default:
+		return -EINVAL;
+	}
+
+	return smk_curacc(ssp, may);
+}
+
+/**
+ * smack_shm_shmat - Smack access for shmat
+ * @shp: the object
+ * @shmaddr: unused
+ * @shmflg: access requested
+ *

security/smack/smack_lsm.c +50 -0

+
+	may = smack_flags_to_may(shmflg);
+	return smk_curacc(ssp, may);
+}
+
+/**
+ * smack_of_sem - the smack pointer for the sem
+ * @sma: the object
+ *
+ * Returns a pointer to the smack value
+ */
+static char *smack_of_sem(struct sem_array *sma)
+{
+	if (sma == NULL)
+		return NULL;
+
+	return (char *)sma->sem_perm.security;
+}
+
+/**
+ * smack_sem_alloc_security - Set the security blob for sem
+ * @sma: the object
+ *
+ * Returns 0
+ */
+static int smack_sem_alloc_security(struct sem_array *sma)
+{
+	struct kern_ipc_perm *isp = &sma->sem_perm;
+
+	isp->security = current->security;
+	return 0;
+}
+
+/**
+ * smack_sem_free_security - Clear the security blob for sem
+ * @sma: the object
+ *
+ * Clears the blob pointer
+ */
+static void smack_sem_free_security(struct sem_array *sma)
+{
+	struct kern_ipc_perm *isp = &sma->sem_perm;
+
+	isp->security = NULL;
+}
+
+/**
+ * smack_sem_associate - Smack access check for sem
+ * @sma: the object
+ * @semflg: access requested

security/smack/smack_lsm.c +9 -0

+
+	may = smack_flags_to_may(semflg);
+	return smk_curacc(ssp, may);
+}
+
+/**
+ * smack_sem_shmctl - Smack access check for sem
+ * @sma: the object
+ * @cmd: what it wants to do

security/smack/smack_lsm.c +38 -0

+
+	switch (cmd) {
+	case GETPID:
+	case GETNCNT:
+	case GETZCNT:
+	case GETVAL:
+	case GETALL:
+	case IPC_STAT:
+	case SEM_STAT:
+		may = MAY_READ;
+		break;
+	case SETVAL:
+	case SETALL:
+	case IPC_RMID:
+	case IPC_SET:
+		may = MAY_READWRITE;
+		break;
+	case IPC_INFO:
+	case SEM_INFO:
+		/*
+		 * System level information
+		 */
+		return 0;
+	default:
+		return -EINVAL;
+	}
+
+	return smk_curacc(ssp, may);
+}
+
+/**
+ * smack_sem_semop - Smack checks of semaphore operations
+ * @sma: the object
+ * @sops: unused
+ * @nsops: unused
+ * @alter: unused
+ *
+ * Treated as read and write in all cases.

security/smack/smack_lsm.c +49 -0

+
+	return smk_curacc(ssp, MAY_READWRITE);
+}
+
+/**
+ * smack_msg_alloc_security - Set the security blob for msg
+ * @msq: the object
+ *
+ * Returns 0
+ */
+static int smack_msg_queue_alloc_security(struct msg_queue *msq)
+{
+	struct kern_ipc_perm *kisp = &msq->q_perm;
+
+	kisp->security = current->security;
+	return 0;
+}
+
+/**
+ * smack_msg_free_security - Clear the security blob for msg
+ * @msq: the object
+ *
+ * Clears the blob pointer
+ */
+static void smack_msg_queue_free_security(struct msg_queue *msq)
+{
+	struct kern_ipc_perm *kisp = &msq->q_perm;
+
+	kisp->security = NULL;
+}
+
+/**
+ * smack_of_msq - the smack pointer for the msq
+ * @msq: the object
+ *
+ * Returns a pointer to the smack value
+ */
+static char *smack_of_msq(struct msg_queue *msq)
+{
+	if (msq == NULL)
+		return NULL;
+
+	return (char *)msq->q_perm.security;
+}
+
+/**
+ * smack_msg_queue_associate - Smack access check for msg_queue
+ * @msq: the object
+ * @msqflg: access requested

security/smack/smack_lsm.c +116 -0

+
+	may = smack_flags_to_may(msqflg);
+	return smk_curacc(msp, may);
+}
+
+/**
+ * smack_msg_queue_msgctl - Smack access check for msg_queue
+ * @msq: the object
+ * @cmd: what it wants to do
+ *
+ * Returns 0 if current has the requested access, error code otherwise
+ */
+static int smack_msg_queue_msgctl(struct msg_queue *msq, int cmd)
+{
+	char *msp = smack_of_msq(msq);
+	int may;
+
+	if (msp == NULL)
+		return 0;
+
+	switch (cmd) {
+	case IPC_STAT:
+	case MSG_STAT:
+		may = MAY_READ;
+		break;
+	case IPC_SET:
+	case IPC_RMID:
+		may = MAY_READWRITE;
+		break;
+	case IPC_INFO:
+	case MSG_INFO:
+		/*
+		 * System level information
+		 */
+		return 0;
+	default:
+		return -EINVAL;
+	}
+
+	return smk_curacc(msp, may);
+}
+
+/**
+ * smack_msg_queue_msgsnd - Smack access check for msg_queue
+ * @msq: the object
+ * @msg: unused
+ * @msqflg: access requested
+ *
+ * Returns 0 if current has the requested access, error code otherwise
+ */
+static int smack_msg_queue_msgsnd(struct msg_queue *msq, struct msg_msg *msg,
+				  int msqflg)
+{
+	char *msp = smack_of_msq(msq);
+	int rc;
+
+	if (msp == NULL)
+		return 0;
+
+	rc = smack_flags_to_may(msqflg);
+	return smk_curacc(msp, rc);
+}
+
+/**
+ * smack_msg_queue_msgsnd - Smack access check for msg_queue
+ * @msq: the object
+ * @msg: unused
+ * @target: unused
+ * @type: unused
+ * @mode: unused
+ *
+ * Returns 0 if current has read and write access, error code otherwise
+ */
+static int smack_msg_queue_msgrcv(struct msg_queue *msq, struct msg_msg *msg,
+			struct task_struct *target, long type, int mode)
+{
+	char *msp = smack_of_msq(msq);
+
+	if (msp == NULL)
+		return 0;
+
+	return smk_curacc(msp, MAY_READWRITE);
+}
+
+/**
+ * smack_ipc_permission - Smack access for ipc_permission()
+ * @ipp: the object permissions
+ * @flag: access requested
+ *
+ * Returns 0 if current has read and write access, error code otherwise
+ */
+static int smack_ipc_permission(struct kern_ipc_perm *ipp, short flag)
+{
+	char *isp = ipp->security;
+	int may;
+
+	may = smack_flags_to_may(flag);
+	return smk_curacc(isp, may);
+}
+
+/**
+ * smack_task_to_inode - copy task smack into the inode blob
+ * @p: task to copy from
+ * inode: inode to copy to
+ *
+ * Sets the smack pointer in the inode security blob
+ */
+static void smack_task_to_inode(struct task_struct *p, struct inode *inode)
+{
+	struct inode_smack *isp = inode->i_security;
+	isp->smk_inode = p->security;
+}
+
+/**
+ * smack_task_wait - Smack access check for waiting
+ * @p: task to wait for

security/smack/smack_lsm.c +8 -0

+
+	/*
+	 * Allow the operation to succeed if either task
+	 * has privilege to perform operations that might
+	 * account for the smack labels having gotten to
+	 * be different in the first place.
+	 *
+	 * This breaks the strict subjet/object access

On Wed, 2007-10-24 at 20:46 -0700, Casey Schaufler wrote:
...

Documentation/Smack.txt line 15

Quoted 6 lines

Documentation/Smack.txt +6 -0

+Smack does not implement Domain Type Enforcement (DTE). If
+you want DTE Linux has an implementation called SELinux.
+Those who really want DTE are encouraged to use SELinux.
+Those who don't know what DTE is are encouraged to compare
+SELinux with Smack to determine which mechanisms are best
+suited to the problem at hand.

Nit: SELinux does not implement DTE. DTE was a scheme introduced by Lee Badger et al to apply implicit typing based on pathname as a variant of the original type enforcement model. SELinux is an implementation of the Flask security architecture for flexible MAC, along with an example security server that implements RBAC, TE, and MLS models, but not limited to them.

diff -uprN -X linux-2.6.24-rc1-base/Documentation/dontdiff linux-2.6.24-rc1-base/security/smack/smack_lsm.c linux-2.6.24-rc1-smack/security/smack/smack_lsm.c

security/smack/smack_lsm.c +0 -0

security/smack/smack_lsm.c +42 -0

+/**
+ * smack_inode_getsecurity - get smack xattrs
+ * @inode: the object
+ * @name: attribute name
+ * @buffer: where to put the result
+ * @size: size of the buffer
+ * @err: unused
+ *
+ * Returns the size of the attribute or an error code
+ */
+static int smack_inode_getsecurity(const struct inode *inode,
+				   const char *name, void *buffer,
+				   size_t size, int err)
+{
+	struct socket_smack *ssp;
+	struct socket *sock;
+	struct super_block *sbp;
+	struct inode *ip = (struct inode *)inode;
+	char *bsp = buffer;
+	char *isp;
+
+	if (size < SMK_LABELLEN || name == NULL || bsp == NULL ||
+	    inode == NULL || inode->i_security == NULL)
+		return 0;
+
+	if (strcmp(name, XATTR_SMACK_SUFFIX) == 0) {
+		isp = smk_of_inode(inode);
+		strncpy(buffer, isp, SMK_LABELLEN);
+		return strlen(isp) + 1;
+	}
+
+	/*
+	 * The rest of the Smack xattrs are only on sockets.
+	 */
+	sbp = ip->i_sb;
+	if (sbp->s_magic != SOCKFS_MAGIC)
+		return -EOPNOTSUPP;
+
+	sock = SOCKET_I(ip);
+	if (sock == NULL)
+		return -EOPNOTSUPP;
+

security/smack/smack_lsm.c +11 -0

+	} else if (strcmp(name, XATTR_SMACK_IPIN) == 0)
+		isp = ssp->smk_in;
+	else if (strcmp(name, XATTR_SMACK_IPOUT) == 0)
+		isp = ssp->smk_out;
+	else
+		return -EOPNOTSUPP;
+
+	strncpy(buffer, isp, SMK_LABELLEN);
+	return strlen(isp) + 1;
+}
+

security/smack/smack_lsm.c +7 -0

+static int smack_socket_recvmsg(struct socket *sock, struct msghdr *msg,
+				int size, int flags)
+{
+	struct socket_smack *ssp = sock->sk->sk_security;
+
+	/*
+	 * If the depth is 0 no packets are queued.

security/smack/smack_lsm.c +36 -0

+
+/**
+ * smack_socket_sock_rcv_skb - Smack packet delivery access check
+ * @sk: socket
+ * @skb: packet
+ *
+ * Returns 0 if the packet should be delivered, an error code otherwise
+ */
+static int smack_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
+{
+	struct netlbl_lsm_secattr secattr;
+	struct socket_smack *ssp = sk->sk_security;
+	char smack[SMK_LABELLEN];
+	int rc;
+
+	if (sk->sk_family != PF_INET && sk->sk_family != PF_INET6)
+		return 0;
+
+	/*
+	 * Translate what netlabel gave us.
+	 */
+	memset(smack, '\0', SMK_LABELLEN);
+	netlbl_secattr_init(&secattr);
+	rc = netlbl_skbuff_getattr(skb, &secattr);
+	if (rc == 0)
+		smack_from_secattr(&secattr, smack);
+	else
+		strncpy(smack, smack_net_ambient, SMK_MAXLEN);
+	netlbl_secattr_destroy(&secattr);
+	/*
+	 * Receiving a packet requires that the other end
+	 * be able to write here. Read access is not required.
+	 * This is the simplist possible security model
+	 * for networking.
+	 */
+	rc = smk_access(smack, ssp->smk_in, MAY_WRITE);

security/smack/smack_lsm.c +4 -0

+
+	return 0;
+}
+

This version is again aimed at addressing Al Viro's issues in smackfs. Ahmed Darwish has again contributed in the repair of the locking issues there. The move to 2.6.24 was also an important release incentive.

Hi Casey,

Quoted 1 line · Casey

Quoted 5 lines

This version is again aimed at addressing Al Viro's issues in smackfs. Ahmed Darwish has again contributed in the repair of the locking issues there. The move to 2.6.24 was also an important release incentive.

My patches mentiond above is not applied in this version. The same lock issues remain. Did you forget applying them ?

security/smack/smackfs.c +12 -0

+/**
+ * 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
+ *
+ * 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)
+{

The problem here (As discussed in private mails) is that the for loop assumes that the beginning of given user-space buffer is the beginning of a rule. This leads to situations where the rule becomes "ecret 20", or "cret 20" instead of "Secret 20". Big input buffers/files leads smack to recieve a rule like "Secret 20" in fragmented chunks like:

write("<lots of rules before ours>\nSec", ..)
write("r", 1, ..)
write("et 20\n<remaing rules after ours>", ..)

Parsing a rule in such tough conditions in _kernel space_ is very hard. I began to feel that it will be much easier if we do the parsing in a userspace utility and let smack accept only small buffers (80 char).

Quoted 10 lines · Ahmed S. Darwish

The problem here (As discussed in private mails) is that the for loop assumes that the beginning of given user-space buffer is the beginning of a rule. This leads to situations where the rule becomes "ecret 20", or "cret 20" instead of "Secret 20". Big input buffers/files leads smack to recieve a rule like "Secret 20" in fragmented chunks like:

write("<lots of rules before ours>\nSec", ..)
write("r", 1, ..)
write("et 20\n<remaing rules after ours>", ..)

Quoted 3 lines

Parsing a rule in such tough conditions in _kernel space_ is very hard. I began to feel that it will be much easier if we do the parsing in a userspace utility and let smack accept only small buffers (80 char).

For crying out louf, all it takes is a finite state machine... BTW, folks, your parser *and* input language suck. Really. Silently allowing noise is Dumb(tm).

Please, write the grammar down and _follow_ _it_.

...

Come on, people, this is ridiculous - why bother reinventing the wheels for the stuff that belongs to exercises halfway through any self-respecting introductory textbook? Scary parser, my arse...

Quoted 10 lines · Ahmed S. Darwish

The problem here (As discussed in private mails) is that the for loop assumes that the beginning of given user-space buffer is the beginning of a rule. This leads to situations where the rule becomes "ecret 20", or "cret 20" instead of "Secret 20". Big input buffers/files leads smack to recieve a rule like "Secret 20" in fragmented chunks like:

write("<lots of rules before ours>\nSec", ..)
write("r", 1, ..)
write("et 20\n<remaing rules after ours>", ..)

Quoted 3 lines

Parsing a rule in such tough conditions in _kernel space_ is very hard. I began to feel that it will be much easier if we do the parsing in a userspace utility and let smack accept only small buffers (80 char).

For crying out louf, all it takes is a finite state machine... BTW, folks, your parser *and* input language suck. Really. Silently allowing noise is Dumb(tm).