diff options
Diffstat (limited to 'security')
| -rw-r--r-- | security/Kconfig | 12 | ||||
| -rw-r--r-- | security/Makefile | 1 | ||||
| -rw-r--r-- | security/seclvl.c | 671 |
3 files changed, 0 insertions, 684 deletions
diff --git a/security/Kconfig b/security/Kconfig index 67785df..460e5c9 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -93,18 +93,6 @@ config SECURITY_ROOTPLUG If you are unsure how to answer this question, answer N. -config SECURITY_SECLVL - tristate "BSD Secure Levels" - depends on SECURITY - select CRYPTO - select CRYPTO_SHA1 - help - Implements BSD Secure Levels as an LSM. See - <file:Documentation/seclvl.txt> for instructions on how to use this - module. - - If you are unsure how to answer this question, answer N. - source security/selinux/Kconfig endmenu diff --git a/security/Makefile b/security/Makefile index 8cbbf2f..ef87df2 100644 --- a/security/Makefile +++ b/security/Makefile @@ -16,4 +16,3 @@ obj-$(CONFIG_SECURITY) += security.o dummy.o inode.o obj-$(CONFIG_SECURITY_SELINUX) += selinux/built-in.o obj-$(CONFIG_SECURITY_CAPABILITIES) += commoncap.o capability.o obj-$(CONFIG_SECURITY_ROOTPLUG) += commoncap.o root_plug.o -obj-$(CONFIG_SECURITY_SECLVL) += seclvl.o diff --git a/security/seclvl.c b/security/seclvl.c deleted file mode 100644 index 8f62919..0000000 --- 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"); |
