[PATCH] Bug fixes and cleanup for the BSD Secure Levels LSM
This patch address several issues in the current BSD Secure Levels code: o plaintext_to_sha1: Missing check for a NULL return from __get_free_page o passwd_write_file: A page is leaked if the password is wrong. o fix securityfs registration order o seclvl_init is a mess and can't properly tolerate failures, failure path is upside down (deldif and delf should be switched) Cleanups: o plaintext_to_sha1: Use buffers passed in o passwd_write_file: Use kmalloc() instead of get_zeroed_page() o passwd_write_file: hashedPassword comparison is just memcmp o s/ENOSYS/EINVAL/ o misc (akpm: after some discussion it appears that the BSD secure levels feature should be scheduled for removal. But for now, let's fix these problems up). Signed-off-by: Davi Arnaut <davi.arnaut@gmail.com> Cc: Michael Halcrow <mhalcrow@us.ibm.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Stephen Smalley <sds@epoch.ncsc.mil> Cc: James Morris <jmorris@namei.org> Cc: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Davi Arnaut
Linus Torvalds
parent
61808c2bbb
commit
6bb08da477
1 changed files with 114 additions and 98 deletions
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@ -8,6 +8,7 @@
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* Copyright (c) 2001 WireX Communications, Inc <chris@wirex.com>
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* Copyright (c) 2001 Greg Kroah-Hartman <greg@kroah.com>
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* Copyright (c) 2002 International Business Machines <robb@austin.ibm.com>
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* Copyright (c) 2006 Davi E. M. Arnaut <davi.arnaut@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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@ -31,6 +32,7 @@
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#include <linux/kobject.h>
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#include <linux/crypto.h>
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#include <asm/scatterlist.h>
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#include <linux/scatterlist.h>
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#include <linux/gfp.h>
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#include <linux/sysfs.h>
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@ -194,35 +196,27 @@ static unsigned char hashedPassword[SHA1_DIGEST_SIZE];
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* people...
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*/
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static int
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plaintext_to_sha1(unsigned char *hash, const char *plaintext, int len)
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plaintext_to_sha1(unsigned char *hash, const char *plaintext, unsigned int len)
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{
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char *pgVirtAddr;
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struct crypto_tfm *tfm;
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struct scatterlist sg[1];
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struct scatterlist sg;
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if (len > PAGE_SIZE) {
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seclvl_printk(0, KERN_ERR, "Plaintext password too large (%d "
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"characters). Largest possible is %lu "
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"bytes.\n", len, PAGE_SIZE);
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return -ENOMEM;
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return -EINVAL;
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}
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tfm = crypto_alloc_tfm("sha1", CRYPTO_TFM_REQ_MAY_SLEEP);
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if (tfm == NULL) {
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seclvl_printk(0, KERN_ERR,
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"Failed to load transform for SHA1\n");
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return -ENOSYS;
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return -EINVAL;
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}
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// Just get a new page; don't play around with page boundaries
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// and scatterlists.
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pgVirtAddr = (char *)__get_free_page(GFP_KERNEL);
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sg[0].page = virt_to_page(pgVirtAddr);
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sg[0].offset = 0;
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sg[0].length = len;
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strncpy(pgVirtAddr, plaintext, len);
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sg_init_one(&sg, (u8 *)plaintext, len);
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crypto_digest_init(tfm);
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crypto_digest_update(tfm, sg, 1);
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crypto_digest_update(tfm, &sg, 1);
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crypto_digest_final(tfm, hash);
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crypto_free_tfm(tfm);
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free_page((unsigned long)pgVirtAddr);
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return 0;
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}
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@ -234,11 +228,9 @@ static ssize_t
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passwd_write_file(struct file * file, const char __user * buf,
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size_t count, loff_t *ppos)
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{
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int i;
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unsigned char tmp[SHA1_DIGEST_SIZE];
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char *page;
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int rc;
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char *p;
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int len;
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unsigned char tmp[SHA1_DIGEST_SIZE];
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if (!*passwd && !*sha1_passwd) {
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seclvl_printk(0, KERN_ERR, "Attempt to password-unlock the "
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@ -251,38 +243,39 @@ passwd_write_file(struct file * file, const char __user * buf,
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return -EINVAL;
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}
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if (count < 0 || count >= PAGE_SIZE)
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if (count >= PAGE_SIZE)
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return -EINVAL;
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if (*ppos != 0)
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return -EINVAL;
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page = (char *)get_zeroed_page(GFP_KERNEL);
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if (!page)
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p = kmalloc(count, GFP_KERNEL);
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if (!p)
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return -ENOMEM;
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len = -EFAULT;
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if (copy_from_user(page, buf, count))
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if (copy_from_user(p, buf, count))
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goto out;
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len = strlen(page);
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len = count;
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/* ``echo "secret" > seclvl/passwd'' includes a newline */
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if (page[len - 1] == '\n')
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if (p[len - 1] == '\n')
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len--;
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/* Hash the password, then compare the hashed values */
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if ((rc = plaintext_to_sha1(tmp, page, len))) {
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if ((len = plaintext_to_sha1(tmp, p, len))) {
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seclvl_printk(0, KERN_ERR, "Error hashing password: rc = "
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"[%d]\n", rc);
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return rc;
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}
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for (i = 0; i < SHA1_DIGEST_SIZE; i++) {
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if (hashedPassword[i] != tmp[i])
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return -EPERM;
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"[%d]\n", len);
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goto out;
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}
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len = -EPERM;
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if (memcmp(hashedPassword, tmp, SHA1_DIGEST_SIZE))
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goto out;
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seclvl_printk(0, KERN_INFO,
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"Password accepted; seclvl reduced to 0.\n");
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seclvl = 0;
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len = count;
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out:
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free_page((unsigned long)page);
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kfree (p);
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return len;
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}
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@ -295,14 +288,12 @@ static struct file_operations passwd_file_ops = {
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*/
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static int seclvl_ptrace(struct task_struct *parent, struct task_struct *child)
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{
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if (seclvl >= 0) {
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if (child->pid == 1) {
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if (seclvl >= 0 && child->pid == 1) {
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seclvl_printk(1, KERN_WARNING, "Attempt to ptrace "
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"the init process dissallowed in "
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"secure level %d\n", seclvl);
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return -EPERM;
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}
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}
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return 0;
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}
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@ -312,55 +303,54 @@ static int seclvl_ptrace(struct task_struct *parent, struct task_struct *child)
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*/
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static int seclvl_capable(struct task_struct *tsk, int cap)
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{
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int rc = 0;
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/* init can do anything it wants */
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if (tsk->pid == 1)
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return 0;
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switch (seclvl) {
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case 2:
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/* fall through */
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case 1:
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if (cap == CAP_LINUX_IMMUTABLE) {
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if (seclvl > 0) {
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rc = -EPERM;
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if (cap == CAP_LINUX_IMMUTABLE)
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seclvl_printk(1, KERN_WARNING, "Attempt to modify "
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"the IMMUTABLE and/or APPEND extended "
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"attribute on a file with the IMMUTABLE "
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"and/or APPEND extended attribute set "
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"denied in seclvl [%d]\n", seclvl);
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return -EPERM;
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} else if (cap == CAP_SYS_RAWIO) { // Somewhat broad...
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else if (cap == CAP_SYS_RAWIO)
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seclvl_printk(1, KERN_WARNING, "Attempt to perform "
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"raw I/O while in secure level [%d] "
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"denied\n", seclvl);
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return -EPERM;
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} else if (cap == CAP_NET_ADMIN) {
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else if (cap == CAP_NET_ADMIN)
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seclvl_printk(1, KERN_WARNING, "Attempt to perform "
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"network administrative task while "
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"in secure level [%d] denied\n", seclvl);
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return -EPERM;
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} else if (cap == CAP_SETUID) {
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else if (cap == CAP_SETUID)
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seclvl_printk(1, KERN_WARNING, "Attempt to setuid "
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"while in secure level [%d] denied\n",
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seclvl);
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return -EPERM;
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} else if (cap == CAP_SETGID) {
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else if (cap == CAP_SETGID)
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seclvl_printk(1, KERN_WARNING, "Attempt to setgid "
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"while in secure level [%d] denied\n",
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seclvl);
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} else if (cap == CAP_SYS_MODULE) {
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else if (cap == CAP_SYS_MODULE)
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seclvl_printk(1, KERN_WARNING, "Attempt to perform "
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"a module operation while in secure "
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"level [%d] denied\n", seclvl);
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return -EPERM;
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else
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rc = 0;
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}
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break;
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default:
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break;
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if (!rc) {
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if (!(cap_is_fs_cap(cap) ? tsk->fsuid == 0 : tsk->euid == 0))
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rc = -EPERM;
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}
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/* from dummy.c */
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if (cap_is_fs_cap(cap) ? tsk->fsuid == 0 : tsk->euid == 0)
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return 0; /* capability granted */
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if (rc)
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seclvl_printk(1, KERN_WARNING, "Capability denied\n");
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return -EPERM; /* capability denied */
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return rc;
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}
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/**
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@ -466,12 +456,9 @@ static int seclvl_inode_setattr(struct dentry *dentry, struct iattr *iattr)
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static void seclvl_file_free_security(struct file *filp)
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{
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struct dentry *dentry = filp->f_dentry;
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struct inode *inode = NULL;
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if (dentry) {
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inode = dentry->d_inode;
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seclvl_bd_release(inode);
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}
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if (dentry)
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seclvl_bd_release(dentry->d_inode);
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}
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/**
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@ -479,9 +466,7 @@ static void seclvl_file_free_security(struct file *filp)
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*/
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static int seclvl_umount(struct vfsmount *mnt, int flags)
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{
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if (current->pid == 1)
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return 0;
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if (seclvl == 2) {
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if (current->pid != 1 && seclvl == 2) {
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seclvl_printk(1, KERN_WARNING, "Attempt to unmount in secure "
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"level %d\n", seclvl);
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return -EPERM;
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@ -505,8 +490,9 @@ static struct security_operations seclvl_ops = {
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static int processPassword(void)
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{
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int rc = 0;
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hashedPassword[0] = '\0';
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if (*passwd) {
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char *p;
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if (*sha1_passwd) {
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seclvl_printk(0, KERN_ERR, "Error: Both "
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"passwd and sha1_passwd "
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@ -514,12 +500,16 @@ static int processPassword(void)
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"exclusive.\n");
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return -EINVAL;
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}
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if ((rc = plaintext_to_sha1(hashedPassword, passwd,
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strlen(passwd)))) {
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p = kstrdup(passwd, GFP_KERNEL);
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if (p == NULL)
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return -ENOMEM;
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if ((rc = plaintext_to_sha1(hashedPassword, p, strlen(p))))
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seclvl_printk(0, KERN_ERR, "Error: SHA1 support not "
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"in kernel\n");
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return rc;
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}
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kfree (p);
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/* All static data goes to the BSS, which zero's the
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* plaintext password out for us. */
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} else if (*sha1_passwd) { // Base 16
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@ -542,7 +532,7 @@ static int processPassword(void)
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sha1_passwd[i + 2] = tmp;
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}
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}
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return 0;
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return rc;
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}
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/**
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@ -552,28 +542,46 @@ struct dentry *dir_ino, *seclvl_ino, *passwd_ino;
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static int seclvlfs_register(void)
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{
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int rc = 0;
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dir_ino = securityfs_create_dir("seclvl", NULL);
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if (!dir_ino)
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return -EFAULT;
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if (IS_ERR(dir_ino))
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return PTR_ERR(dir_ino);
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seclvl_ino = securityfs_create_file("seclvl", S_IRUGO | S_IWUSR,
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dir_ino, &seclvl, &seclvl_file_ops);
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if (!seclvl_ino)
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if (IS_ERR(seclvl_ino)) {
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rc = PTR_ERR(seclvl_ino);
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goto out_deldir;
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}
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if (*passwd || *sha1_passwd) {
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passwd_ino = securityfs_create_file("passwd", S_IRUGO | S_IWUSR,
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dir_ino, NULL, &passwd_file_ops);
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if (!passwd_ino)
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if (IS_ERR(passwd_ino)) {
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rc = PTR_ERR(passwd_ino);
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goto out_delf;
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}
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return 0;
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}
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return rc;
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out_deldir:
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securityfs_remove(dir_ino);
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out_delf:
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securityfs_remove(seclvl_ino);
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return -EFAULT;
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out_deldir:
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securityfs_remove(dir_ino);
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return rc;
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}
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static void seclvlfs_unregister(void)
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{
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securityfs_remove(seclvl_ino);
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if (*passwd || *sha1_passwd)
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securityfs_remove(passwd_ino);
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securityfs_remove(dir_ino);
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}
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/**
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@ -582,6 +590,8 @@ static int seclvlfs_register(void)
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static int __init seclvl_init(void)
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{
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int rc = 0;
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static char once;
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if (verbosity < 0 || verbosity > 1) {
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printk(KERN_ERR "Error: bad verbosity [%d]; only 0 or 1 "
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"are valid values\n", verbosity);
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@ -600,6 +610,11 @@ static int __init seclvl_init(void)
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"module parameter(s): rc = [%d]\n", rc);
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goto exit;
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}
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if ((rc = seclvlfs_register())) {
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seclvl_printk(0, KERN_ERR, "Error registering with sysfs\n");
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goto exit;
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}
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/* register ourselves with the security framework */
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if (register_security(&seclvl_ops)) {
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seclvl_printk(0, KERN_ERR,
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@ -611,20 +626,24 @@ static int __init seclvl_init(void)
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seclvl_printk(0, KERN_ERR, "seclvl: Failure "
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"registering with primary security "
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"module.\n");
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seclvlfs_unregister();
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goto exit;
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} /* if primary module registered */
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secondary = 1;
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} /* if we registered ourselves with the security framework */
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if ((rc = seclvlfs_register())) {
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seclvl_printk(0, KERN_ERR, "Error registering with sysfs\n");
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goto exit;
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}
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seclvl_printk(0, KERN_INFO, "seclvl: Successfully initialized.\n");
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if (once) {
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once = 1;
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seclvl_printk(0, KERN_INFO, "seclvl is going away. It has been "
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"buggy for ages. Also, be warned that "
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"Securelevels are useless.");
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}
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exit:
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if (rc) {
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if (rc)
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printk(KERN_ERR "seclvl: Error during initialization: rc = "
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"[%d]\n", rc);
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}
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return rc;
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}
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@ -633,18 +652,15 @@ static int __init seclvl_init(void)
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*/
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static void __exit seclvl_exit(void)
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{
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securityfs_remove(seclvl_ino);
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if (*passwd || *sha1_passwd)
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securityfs_remove(passwd_ino);
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securityfs_remove(dir_ino);
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if (secondary == 1) {
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seclvlfs_unregister();
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if (secondary)
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mod_unreg_security(MY_NAME, &seclvl_ops);
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} else if (unregister_security(&seclvl_ops)) {
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else if (unregister_security(&seclvl_ops))
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seclvl_printk(0, KERN_INFO,
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"seclvl: Failure unregistering with the "
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"kernel\n");
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}
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}
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module_init(seclvl_init);
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module_exit(seclvl_exit);
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