[PATCH] LSM: remove BSD secure level security module

This code has suffered from broken core design and lack of developer
attention.  Broken security modules are too dangerous to leave around.  It
is time to remove this one.

Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Acked-by: Michael Halcrow <mhalcrow@us.ibm.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Davi Arnaut <davi.arnaut@gmail.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: James Morris <jmorris@namei.org>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 0 insertions, 671 deletions

diff --git a/security/seclvl.c b/security/seclvl.c
deleted file mode 100644
index 8f6291991fb..00000000000
--- a/security/seclvl.c
+++ /dev/null
@@ -1,671 +0,0 @@
-/**
- * BSD Secure Levels LSM
- *
- * Maintainers:
- *	Michael A. Halcrow <mike@halcrow.us>
- *	Serge Hallyn <hallyn@cs.wm.edu>
- *
- * Copyright (c) 2001 WireX Communications, Inc <chris@wirex.com>
- * Copyright (c) 2001 Greg Kroah-Hartman <greg@kroah.com>
- * Copyright (c) 2002 International Business Machines <robb@austin.ibm.com>
- * Copyright (c) 2006 Davi E. M. Arnaut <davi.arnaut@gmail.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; either version 2 of the License, or
- *	(at your option) any later version.
- */
-
-#include <linux/err.h>
-#include <linux/module.h>
-#include <linux/moduleparam.h>
-#include <linux/kernel.h>
-#include <linux/init.h>
-#include <linux/security.h>
-#include <linux/netlink.h>
-#include <linux/fs.h>
-#include <linux/namei.h>
-#include <linux/mount.h>
-#include <linux/capability.h>
-#include <linux/time.h>
-#include <linux/proc_fs.h>
-#include <linux/kobject.h>
-#include <linux/crypto.h>
-#include <asm/scatterlist.h>
-#include <linux/scatterlist.h>
-#include <linux/gfp.h>
-#include <linux/sysfs.h>
-
-#define SHA1_DIGEST_SIZE 20
-
-/**
- * Module parameter that defines the initial secure level.
- *
- * When built as a module, it defaults to seclvl 1, which is the
- * behavior of BSD secure levels.  Note that this default behavior
- * wrecks havoc on a machine when the seclvl module is compiled into
- * the kernel.	In that case, we default to seclvl 0.
- */
-#ifdef CONFIG_SECURITY_SECLVL_MODULE
-static int initlvl = 1;
-#else
-static int initlvl;
-#endif
-module_param(initlvl, int, 0);
-MODULE_PARM_DESC(initlvl, "Initial secure level (defaults to 1)");
-
-/* Module parameter that defines the verbosity level */
-static int verbosity;
-module_param(verbosity, int, 0);
-MODULE_PARM_DESC(verbosity, "Initial verbosity level (0 or 1; defaults to "
-		 "0, which is Quiet)");
-
-/**
- * Optional password which can be passed in to bring seclvl to 0
- * (i.e., for halt/reboot).  Defaults to NULL (the passwd attribute
- * file will not be registered in sysfs).
- *
- * This gets converted to its SHA1 hash when stored.  It's probably
- * not a good idea to use this parameter when loading seclvl from a
- * script; use sha1_passwd instead.
- */
-
-#define MAX_PASSWD_SIZE	32
-static char passwd[MAX_PASSWD_SIZE];
-module_param_string(passwd, passwd, sizeof(passwd), 0);
-MODULE_PARM_DESC(passwd,
-		 "Plaintext of password that sets seclvl=0 when written to "
-		 "(sysfs mount point)/seclvl/passwd\n");
-
-/**
- * SHA1 hashed version of the optional password which can be passed in
- * to bring seclvl to 0 (i.e., for halt/reboot).  Must be in
- * hexadecimal format (40 characters).	Defaults to NULL (the passwd
- * attribute file will not be registered in sysfs).
- *
- * Use the sha1sum utility to generate the SHA1 hash of a password:
- *
- * echo -n "secret" | sha1sum
- */
-#define MAX_SHA1_PASSWD	41
-static char sha1_passwd[MAX_SHA1_PASSWD];
-module_param_string(sha1_passwd, sha1_passwd, sizeof(sha1_passwd), 0);
-MODULE_PARM_DESC(sha1_passwd,
-		 "SHA1 hash (40 hexadecimal characters) of password that "
-		 "sets seclvl=0 when plaintext password is written to "
-		 "(sysfs mount point)/seclvl/passwd\n");
-
-static int hideHash = 1;
-module_param(hideHash, int, 0);
-MODULE_PARM_DESC(hideHash, "When set to 0, reading seclvl/passwd from sysfs "
-		 "will return the SHA1-hashed value of the password that "
-		 "lowers the secure level to 0.\n");
-
-#define MY_NAME "seclvl"
-
-/**
- * This time-limits log writes to one per second.
- */
-#define seclvl_printk(verb, type, fmt, arg...)			\
-	do {							\
-		if (verbosity >= verb) {			\
-			static unsigned long _prior;		\
-			unsigned long _now = jiffies;		\
-			if ((_now - _prior) > HZ) {		\
-				printk(type "%s: %s: " fmt,	\
-					MY_NAME, __FUNCTION__ ,	\
-					## arg);		\
-				_prior = _now;			\
-			}					\
-		}						\
-	} while (0)
-
-/**
- * The actual security level.  Ranges between -1 and 2 inclusive.
- */
-static int seclvl;
-
-/**
- * flag to keep track of how we were registered
- */
-static int secondary;
-
-/**
- * Verifies that the requested secure level is valid, given the current
- * secure level.
- */
-static int seclvl_sanity(int reqlvl)
-{
-	if ((reqlvl < -1) || (reqlvl > 2)) {
-		seclvl_printk(1, KERN_WARNING, "Attempt to set seclvl out of "
-			      "range: [%d]\n", reqlvl);
-		return -EINVAL;
-	}
-	if ((seclvl == 0) && (reqlvl == -1))
-		return 0;
-	if (reqlvl < seclvl) {
-		seclvl_printk(1, KERN_WARNING, "Attempt to lower seclvl to "
-			      "[%d]\n", reqlvl);
-		return -EPERM;
-	}
-	return 0;
-}
-
-/**
- * security level advancement rules:
- *   Valid levels are -1 through 2, inclusive.
- *   From -1, stuck.  [ in case compiled into kernel ]
- *   From 0 or above, can only increment.
- */
-static void do_seclvl_advance(void *data, u64 val)
-{
-	int ret;
-	int newlvl = (int)val;
-
-	ret = seclvl_sanity(newlvl);
-	if (ret)
-		return;
-
-	if (newlvl > 2) {
-		seclvl_printk(1, KERN_WARNING, "Cannot advance to seclvl "
-			      "[%d]\n", newlvl);
-		return;
-	}
-	if (seclvl == -1) {
-		seclvl_printk(1, KERN_WARNING, "Not allowed to advance to "
-			      "seclvl [%d]\n", seclvl);
-		return;
-	}
-	seclvl = newlvl;  /* would it be more "correct" to set *data? */
-	return;
-}
-
-static u64 seclvl_int_get(void *data)
-{
-	return *(int *)data;
-}
-
-DEFINE_SIMPLE_ATTRIBUTE(seclvl_file_ops, seclvl_int_get, do_seclvl_advance, "%lld\n");
-
-static unsigned char hashedPassword[SHA1_DIGEST_SIZE];
-
-/**
- * Converts a block of plaintext of into its SHA1 hashed value.
- *
- * It would be nice if crypto had a wrapper to do this for us linear
- * people...
- */
-static int
-plaintext_to_sha1(unsigned char *hash, const char *plaintext, unsigned int len)
-{
-	struct hash_desc desc;
-	struct scatterlist sg;
-	int err;
-
-	if (len > PAGE_SIZE) {
-		seclvl_printk(0, KERN_ERR, "Plaintext password too large (%d "
-			      "characters).  Largest possible is %lu "
-			      "bytes.\n", len, PAGE_SIZE);
-		return -EINVAL;
-	}
-	desc.tfm = crypto_alloc_hash("sha1", 0, CRYPTO_ALG_ASYNC);
-	if (IS_ERR(desc.tfm)) {
-		seclvl_printk(0, KERN_ERR,
-			      "Failed to load transform for SHA1\n");
-		return -EINVAL;
-	}
-	sg_init_one(&sg, (u8 *)plaintext, len);
-	desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
-	err = crypto_hash_digest(&desc, &sg, len, hash);
-	crypto_free_hash(desc.tfm);
-	return err;
-}
-
-/**
- * Called whenever the user writes to the sysfs passwd handle to this kernel
- * object.  It hashes the password and compares the hashed results.
- */
-static ssize_t
-passwd_write_file(struct file * file, const char __user * buf,
-				size_t count, loff_t *ppos)
-{
-	char *p;
-	int len;
-	unsigned char tmp[SHA1_DIGEST_SIZE];
-
-	if (!*passwd && !*sha1_passwd) {
-		seclvl_printk(0, KERN_ERR, "Attempt to password-unlock the "
-			      "seclvl module, but neither a plain text "
-			      "password nor a SHA1 hashed password was "
-			      "passed in as a module parameter!  This is a "
-			      "bug, since it should not be possible to be in "
-			      "this part of the module; please tell a "
-			      "maintainer about this event.\n");
-		return -EINVAL;
-	}
-
-	if (count >= PAGE_SIZE)
-		return -EINVAL;
-	if (*ppos != 0)
-		return -EINVAL;
-	p = kmalloc(count, GFP_KERNEL);
-	if (!p)
-		return -ENOMEM;
-	len = -EFAULT;
-	if (copy_from_user(p, buf, count))
-		goto out;
-	
-	len = count;
-	/* ``echo "secret" > seclvl/passwd'' includes a newline */
-	if (p[len - 1] == '\n')
-		len--;
-	/* Hash the password, then compare the hashed values */
-	if ((len = plaintext_to_sha1(tmp, p, len))) {
-		seclvl_printk(0, KERN_ERR, "Error hashing password: rc = "
-			      "[%d]\n", len);
-		goto out;
-	}
-
-	len = -EPERM;
-	if (memcmp(hashedPassword, tmp, SHA1_DIGEST_SIZE))
-		goto out;
-
-	seclvl_printk(0, KERN_INFO,
-		      "Password accepted; seclvl reduced to 0.\n");
-	seclvl = 0;
-	len = count;
-
-out:
-	kfree (p);
-	return len;
-}
-
-static struct file_operations passwd_file_ops = {
-	.write = passwd_write_file,
-};
-
-/**
- * Explicitely disallow ptrace'ing the init process.
- */
-static int seclvl_ptrace(struct task_struct *parent, struct task_struct *child)
-{
-	if (seclvl >= 0 && child->pid == 1) {
-		seclvl_printk(1, KERN_WARNING, "Attempt to ptrace "
-			      "the init process dissallowed in "
-			      "secure level %d\n", seclvl);
-		return -EPERM;
-	}
-	return 0;
-}
-
-/**
- * Capability checks for seclvl.  The majority of the policy
- * enforcement for seclvl takes place here.
- */
-static int seclvl_capable(struct task_struct *tsk, int cap)
-{
-	int rc = 0;
-
-	/* init can do anything it wants */
-	if (tsk->pid == 1)
-		return 0;
-
-	if (seclvl > 0) {
-		rc = -EPERM;
-
-		if (cap == CAP_LINUX_IMMUTABLE)
-			seclvl_printk(1, KERN_WARNING, "Attempt to modify "
-				      "the IMMUTABLE and/or APPEND extended "
-				      "attribute on a file with the IMMUTABLE "
-				      "and/or APPEND extended attribute set "
-				      "denied in seclvl [%d]\n", seclvl);
-		else if (cap == CAP_SYS_RAWIO)
-			seclvl_printk(1, KERN_WARNING, "Attempt to perform "
-				      "raw I/O while in secure level [%d] "
-				      "denied\n", seclvl);
-		else if (cap == CAP_NET_ADMIN)
-			seclvl_printk(1, KERN_WARNING, "Attempt to perform "
-				      "network administrative task while "
-				      "in secure level [%d] denied\n", seclvl);
-		else if (cap == CAP_SETUID)
-			seclvl_printk(1, KERN_WARNING, "Attempt to setuid "
-				      "while in secure level [%d] denied\n",
-				      seclvl);
-		else if (cap == CAP_SETGID)
-			seclvl_printk(1, KERN_WARNING, "Attempt to setgid "
-				      "while in secure level [%d] denied\n",
-				      seclvl);
-		else if (cap == CAP_SYS_MODULE)
-			seclvl_printk(1, KERN_WARNING, "Attempt to perform "
-				      "a module operation while in secure "
-				      "level [%d] denied\n", seclvl);
-		else
-			rc = 0;
-	}
-
-	if (!rc) {
-		if (!(cap_is_fs_cap(cap) ? tsk->fsuid == 0 : tsk->euid == 0))
-			rc = -EPERM;
-	}
-
-	if (rc)
-		seclvl_printk(1, KERN_WARNING, "Capability denied\n");
-
-	return rc;
-}
-
-/**
- * Disallow reversing the clock in seclvl > 1
- */
-static int seclvl_settime(struct timespec *tv, struct timezone *tz)
-{
-	if (tv && seclvl > 1) {
-		struct timespec now;
-		now = current_kernel_time();
-		if (tv->tv_sec < now.tv_sec ||
-		    (tv->tv_sec == now.tv_sec && tv->tv_nsec < now.tv_nsec)) {
-			seclvl_printk(1, KERN_WARNING, "Attempt to decrement "
-				      "time in secure level %d denied: "
-				      "current->pid = [%d], "
-				      "current->group_leader->pid = [%d]\n",
-				      seclvl, current->pid,
-				      current->group_leader->pid);
-			return -EPERM;
-		}		/* if attempt to decrement time */
-	}			/* if seclvl > 1 */
-	return 0;
-}
-
-/* claim the blockdev to exclude mounters, release on file close */
-static int seclvl_bd_claim(struct inode *inode)
-{
-	int holder;
-	struct block_device *bdev = NULL;
-	dev_t dev = inode->i_rdev;
-	bdev = open_by_devnum(dev, FMODE_WRITE);
-	if (bdev) {
-		if (bd_claim(bdev, &holder)) {
-			blkdev_put(bdev);
-			return -EPERM;
-		}
-		/* claimed, mark it to release on close */
-		inode->i_security = current;
-	}
-	return 0;
-}
-
-/* release the blockdev if you claimed it */
-static void seclvl_bd_release(struct inode *inode)
-{
-	if (inode && S_ISBLK(inode->i_mode) && inode->i_security == current) {
-		struct block_device *bdev = inode->i_bdev;
-		if (bdev) {
-			bd_release(bdev);
-			blkdev_put(bdev);
-			inode->i_security = NULL;
-		}
-	}
-}
-
-/**
- * Security for writes to block devices is regulated by this seclvl
- * function.  Deny all writes to block devices in seclvl 2.  In
- * seclvl 1, we only deny writes to *mounted* block devices.
- */
-static int
-seclvl_inode_permission(struct inode *inode, int mask, struct nameidata *nd)
-{
-	if (current->pid != 1 && S_ISBLK(inode->i_mode) && (mask & MAY_WRITE)) {
-		switch (seclvl) {
-		case 2:
-			seclvl_printk(1, KERN_WARNING, "Write to block device "
-				      "denied in secure level [%d]\n", seclvl);
-			return -EPERM;
-		case 1:
-			if (seclvl_bd_claim(inode)) {
-				seclvl_printk(1, KERN_WARNING,
-					      "Write to mounted block device "
-					      "denied in secure level [%d]\n",
-					      seclvl);
-				return -EPERM;
-			}
-		}
-	}
-	return 0;
-}
-
-/**
- * The SUID and SGID bits cannot be set in seclvl >= 1
- */
-static int seclvl_inode_setattr(struct dentry *dentry, struct iattr *iattr)
-{
-	if (seclvl > 0) {
-		if (iattr->ia_valid & ATTR_MODE)
-			if (iattr->ia_mode & S_ISUID ||
-			    iattr->ia_mode & S_ISGID) {
-				seclvl_printk(1, KERN_WARNING, "Attempt to "
-					      "modify SUID or SGID bit "
-					      "denied in seclvl [%d]\n",
-					      seclvl);
-				return -EPERM;
-			}
-	}
-	return 0;
-}
-
-/* release busied block devices */
-static void seclvl_file_free_security(struct file *filp)
-{
-	struct dentry *dentry = filp->f_dentry;
-
-	if (dentry)
-		seclvl_bd_release(dentry->d_inode);
-}
-
-/**
- * Cannot unmount in secure level 2
- */
-static int seclvl_umount(struct vfsmount *mnt, int flags)
-{
-	if (current->pid != 1 && seclvl == 2) {
-		seclvl_printk(1, KERN_WARNING, "Attempt to unmount in secure "
-			      "level %d\n", seclvl);
-		return -EPERM;
-	}
-	return 0;
-}
-
-static struct security_operations seclvl_ops = {
-	.ptrace = seclvl_ptrace,
-	.capable = seclvl_capable,
-	.inode_permission = seclvl_inode_permission,
-	.inode_setattr = seclvl_inode_setattr,
-	.file_free_security = seclvl_file_free_security,
-	.settime = seclvl_settime,
-	.sb_umount = seclvl_umount,
-};
-
-/**
- * Process the password-related module parameters
- */
-static int processPassword(void)
-{
-	int rc = 0;
-	if (*passwd) {
-		char *p;
-
-		if (*sha1_passwd) {
-			seclvl_printk(0, KERN_ERR, "Error: Both "
-				      "passwd and sha1_passwd "
-				      "were set, but they are mutually "
-				      "exclusive.\n");
-			return -EINVAL;
-		}
-
-		p = kstrdup(passwd, GFP_KERNEL);
-		if (p == NULL)
-			return -ENOMEM;
-
-		if ((rc = plaintext_to_sha1(hashedPassword, p, strlen(p))))
-			seclvl_printk(0, KERN_ERR, "Error: SHA1 support not "
-				      "in kernel\n");
-
-		kfree (p);
-		/* All static data goes to the BSS, which zero's the
-		 * plaintext password out for us. */
-	} else if (*sha1_passwd) {	// Base 16
-		int i;
-		i = strlen(sha1_passwd);
-		if (i != (SHA1_DIGEST_SIZE * 2)) {
-			seclvl_printk(0, KERN_ERR, "Received [%d] bytes; "
-				      "expected [%d] for the hexadecimal "
-				      "representation of the SHA1 hash of "
-				      "the password.\n",
-				      i, (SHA1_DIGEST_SIZE * 2));
-			return -EINVAL;
-		}
-		while ((i -= 2) + 2) {
-			unsigned char tmp;
-			tmp = sha1_passwd[i + 2];
-			sha1_passwd[i + 2] = '\0';
-			hashedPassword[i / 2] = (unsigned char)
-			    simple_strtol(&sha1_passwd[i], NULL, 16);
-			sha1_passwd[i + 2] = tmp;
-		}
-	}
-	return rc;
-}
-
-/**
- * securityfs registrations
- */
-struct dentry *dir_ino, *seclvl_ino, *passwd_ino;
-
-static int seclvlfs_register(void)
-{
-	int rc = 0;
-
-	dir_ino = securityfs_create_dir("seclvl", NULL);
-
-	if (IS_ERR(dir_ino))
-		return PTR_ERR(dir_ino);
-
-	seclvl_ino = securityfs_create_file("seclvl", S_IRUGO | S_IWUSR,
-				dir_ino, &seclvl, &seclvl_file_ops);
-	if (IS_ERR(seclvl_ino)) {
-		rc = PTR_ERR(seclvl_ino);
-		goto out_deldir;
-	}
-	if (*passwd || *sha1_passwd) {
-		passwd_ino = securityfs_create_file("passwd", S_IRUGO | S_IWUSR,
-				dir_ino, NULL, &passwd_file_ops);
-		if (IS_ERR(passwd_ino)) {
-			rc = PTR_ERR(passwd_ino);
-			goto out_delf;
-		}
-	}
-	return rc;
-
-out_delf:
-	securityfs_remove(seclvl_ino);
-
-out_deldir:
-	securityfs_remove(dir_ino);
-
-	return rc;
-}
-
-static void seclvlfs_unregister(void)
-{
-	securityfs_remove(seclvl_ino);
-
-	if (*passwd || *sha1_passwd)
-		securityfs_remove(passwd_ino);
-
-	securityfs_remove(dir_ino);
-}
-
-/**
- * Initialize the seclvl module.
- */
-static int __init seclvl_init(void)
-{
-	int rc = 0;
-	static char once;
-
-	if (verbosity < 0 || verbosity > 1) {
-		printk(KERN_ERR "Error: bad verbosity [%d]; only 0 or 1 "
-		       "are valid values\n", verbosity);
-		rc = -EINVAL;
-		goto exit;
-	}
-	if (initlvl < -1 || initlvl > 2) {
-		seclvl_printk(0, KERN_ERR, "Error: bad initial securelevel "
-			      "[%d].\n", initlvl);
-		rc = -EINVAL;
-		goto exit;
-	}
-	seclvl = initlvl;
-	if ((rc = processPassword())) {
-		seclvl_printk(0, KERN_ERR, "Error processing the password "
-			      "module parameter(s): rc = [%d]\n", rc);
-		goto exit;
-	}
-
-	if ((rc = seclvlfs_register())) {
-		seclvl_printk(0, KERN_ERR, "Error registering with sysfs\n");
-		goto exit;
-	}
-	/* register ourselves with the security framework */
-	if (register_security(&seclvl_ops)) {
-		seclvl_printk(0, KERN_ERR,
-			      "seclvl: Failure registering with the "
-			      "kernel.\n");
-		/* try registering with primary module */
-		rc = mod_reg_security(MY_NAME, &seclvl_ops);
-		if (rc) {
-			seclvl_printk(0, KERN_ERR, "seclvl: Failure "
-				      "registering with primary security "
-				      "module.\n");
-			seclvlfs_unregister();
-			goto exit;
-		}		/* if primary module registered */
-		secondary = 1;
-	}			/* if we registered ourselves with the security framework */
-
-	seclvl_printk(0, KERN_INFO, "seclvl: Successfully initialized.\n");
-
-	if (once) {
-		once = 1;
-		seclvl_printk(0, KERN_INFO, "seclvl is going away. It has been "
-				"buggy for ages. Also, be warned that "
-				"Securelevels are useless.");
-	}
- exit:
-	if (rc)
-		printk(KERN_ERR "seclvl: Error during initialization: rc = "
-		       "[%d]\n", rc);
-	return rc;
-}
-
-/**
- * Remove the seclvl module.
- */
-static void __exit seclvl_exit(void)
-{
-	seclvlfs_unregister();
-
-	if (secondary)
-		mod_unreg_security(MY_NAME, &seclvl_ops);
-	else if (unregister_security(&seclvl_ops))
-		seclvl_printk(0, KERN_INFO,
-			      "seclvl: Failure unregistering with the "
-			      "kernel\n");
-}
-
-module_init(seclvl_init);
-module_exit(seclvl_exit);
-
-MODULE_AUTHOR("Michael A. Halcrow <mike@halcrow.us>");
-MODULE_DESCRIPTION("LSM implementation of the BSD Secure Levels");
-MODULE_LICENSE("GPL");