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Subject[RFC][Patch 3/6] integrity: EVM as an integrity service provider
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This is a re-release of EVM as an integrity service provider.  The
initial EVM release was as an LSM module. It has been substantially
rewritten to provide support for the new integrity service framework
API, which permits applications, such as LSM modules, to verify the
integrity of the metadata and data of a file.

EVM maintains an HMAC-sha1 associated with each file across an
extensible set of extended attributes, ensuring that the extended
attributes are protected against integrity attacks. The HMAC-sha1 is
stored as an extended attribute security.evm.hmac. EVM depends on the
Kernel Key Retention System to provide it with the kernel master key
for the HMAC operation. The kernel master key is loaded onto the
root's keyring by 'loadkernkey', which either uses the TPM sealed
secrect key, if available, or a password requested from the console.

The integrity measurement of the file data, stored in the extended
attribute security.evm.hash (md5) or security.evm.sha1, is protected
by the HMAC. EVM maintains the integrity measurement of the file data,
unless the file is defined as either FIXED or NOHASH.

The integrity service framework API defines three calls:
integrity_verify_metadata(), integrity_verify_data(), and
integrity_measure(). For integrity_verify_metadata(), EVM determines
whether or not the HMAC calculated for the set of extended attributes
matches the HMAC stored as an extended attribute; for
integrity_verify_data(), EVM determines whether or not the integrity
measurement of the file data matches the value stored as an extended
attribute; and for integrity_measure(), if IMA is configured and
enabled, EVM passes the integrity measurement to it.

Index: linux-2.6.21-rc3-mm2/security/evm/evm_config.c
===================================================================
--- /dev/null
+++ linux-2.6.21-rc3-mm2/security/evm/evm_config.c
@@ -0,0 +1,129 @@
+/*
+ * EVM - Extended Verification Module
+ *
+ * Copyright (C) 2005,2006,2007 IBM Corporation
+ * Author: Mimi Zohar <zohar@us.ibm.com>
+ * Kylene Hall <kjhall@us.ibm.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, version 2 of the License.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include "evm.h"
+
+/*
+ * Configuration data
+ */
+struct evm_xattr_config *evm_config_xattrdata;
+int evm_config_xattrnum = 0; /* number of extended attributes */
+
+/*
+ * inode->i_integrity information
+ */
+void display_config(const char *name)
+{
+ struct evm_xattr_config *config_p;
+
+ for_each_xattr(config_p, evm_config_xattrdata, evm_config_xattrnum)
+ printk(KERN_INFO "%s: %s\n", name, config_p->xattr_name);
+}
+
+/*
+ * Initialize the Extended Verification module
+ */
+int evm_init_config(struct evm_xattr_config *evm_data, int evm_datasize)
+{
+ ssize_t error = 0;
+
+ if (evm_datasize > 0) {
+ evm_config_xattrdata = evm_data;
+ evm_config_xattrnum = evm_datasize;
+ display_config(__FUNCTION__);
+
+ } else {
+ printk(KERN_INFO "%s: config file definition missing\n",
+ __FUNCTION__);
+ return -EINVAL;
+ }
+ return error;
+}
+
+static char *get_tag(char *buf_start, char *buf_end, char delimiter,
+ int *taglen)
+{
+ char *bufp = buf_start;
+ char *tag;
+
+ /* Get start of tag */
+ while (bufp < buf_end) {
+ if (*bufp == ' ') /* skip blanks */
+ while ((*bufp == ' ') && (bufp++ < buf_end)) ;
+ else if (*bufp == '#') { /* skip comment */
+ while ((*bufp != '\n') && (bufp++ < buf_end)) ;
+ bufp++;
+ } else if (*bufp == '\n') /* skip newline */
+ bufp++;
+ else if (*bufp == '\t') /* skip tabs */
+ bufp++;
+ else
+ break;
+ }
+ if (bufp < buf_end)
+ tag = bufp;
+ else
+ return NULL;
+
+ /* Get tag */
+ *taglen = 0;
+ while ((bufp < buf_end) && (*taglen == 0)) {
+ if ((*bufp == delimiter) || (*bufp == '\n'))
+ *taglen = bufp - tag;
+ bufp++;
+ }
+ if (*taglen == 0) /* Didn't find end delimiter */
+ *taglen = bufp - tag;
+ return tag;
+}
+
+struct evm_xattr_config *evm_parse_config(char *data, unsigned long datalen,
+ int *xattrnum)
+{
+ char *datap, *dataend, *tag;
+ int num_xattr = 0;
+ struct evm_xattr_config *config_xattrdata = NULL, *config_p;
+ int taglen;
+
+ /* Get number of extended attribute definitions */
+ datap = data;
+ dataend = data + datalen;
+
+ while ((tag = get_tag(datap, dataend, ' ', &taglen)) != NULL) {
+ datap = tag + taglen;
+ num_xattr++;
+ }
+ *xattrnum = num_xattr;
+
+ datap = data;
+ config_xattrdata =
+ kmalloc(num_xattr * sizeof(struct evm_xattr_config), GFP_KERNEL);
+ if (!config_xattrdata)
+ return NULL;
+
+ /* Get the list of hmac protected extended attributes */
+ config_p = config_xattrdata;
+ while ((tag = get_tag(datap, dataend, ' ', &taglen)) != NULL) {
+ datap = tag == NULL ? dataend : tag + taglen;
+ memset(config_p->xattr_name, 0, sizeof config_p->xattr_name);
+ memcpy(config_p->xattr_name, tag, taglen);
+ config_p++;
+ }
+ return config_xattrdata;
+}
+
+inline void evm_cleanup_config(void)
+{
+ kfree(evm_config_xattrdata);
+}
Index: linux-2.6.21-rc3-mm2/security/evm/evm_crypto.c
===================================================================
--- /dev/null
+++ linux-2.6.21-rc3-mm2/security/evm/evm_crypto.c
@@ -0,0 +1,350 @@
+/*
+ * evm_crypto.c
+
+ * Functions which calculate a hash/hmac using root's kernel master key (kmk)
+ *
+ * Copyright (C) 2005,2006,2007 IBM Corporation
+ * Author: Mimi Zohar <zohar@us.ibm.com>
+ * Kylene Hall <kjhall@us.ibm.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, version 2 of the License.
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/security.h>
+#include <linux/mount.h>
+#include <linux/crypto.h>
+#include <linux/mm.h>
+#include <linux/xattr.h>
+#include <keys/user-type.h>
+#include <asm/scatterlist.h>
+#include "evm.h"
+
+#define TPMKEY "evm_key"
+#define MAX_TPMKEY 128
+static unsigned char tpm_key[MAX_TPMKEY];
+static int tpm_keylen = MAX_TPMKEY;
+
+int update_file_hash(struct dentry *dentry, struct file *f,
+ struct hash_desc *desc)
+{
+ struct file *file = f;
+ struct scatterlist sg[1];
+ loff_t i_size;
+ int error = 0;
+
+ char *rbuf = NULL;
+ int rbuf_len = 0;
+ int offset = 0;
+
+ if (!file) {
+ file = dentry_open(dget(dentry), NULL, O_RDONLY);
+ if (IS_ERR(file)) {
+ printk(KERN_INFO "%s: dentry_open failed\n",
+ __FUNCTION__);
+ error = -ENOENT;
+ dput(dentry);
+ file = NULL;
+ goto out;
+ }
+ }
+
+ rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!rbuf) {
+ error = -ENOMEM;
+ goto out;
+ }
+
+ i_size = i_size_read(file->f_dentry->d_inode);
+ while (offset < i_size) {
+ rbuf_len = kernel_read(file, offset, rbuf, PAGE_SIZE);
+ if (rbuf_len <= 0)
+ break;
+ offset += rbuf_len;
+ sg[0].page = virt_to_page(rbuf);
+ sg[0].offset = ((long)rbuf & ~PAGE_MASK);
+ sg[0].length = rbuf_len;
+
+ crypto_hash_update(desc, sg, rbuf_len);
+ }
+
+ kfree(rbuf);
+out:
+ if (file && !f)
+ fput(file); /* clean up dentry_open() */
+ return error;
+}
+
+int update_link_hash(struct dentry *dentry, struct hash_desc *desc)
+{
+ struct scatterlist sg[1];
+ int error = 0;
+ char *rbuf = NULL;
+ int rbuf_len = 0;
+
+ if (dentry->d_inode->i_op->readlink == generic_readlink)
+ error = kernel_readlink(dentry, &rbuf, &rbuf_len);
+ else {
+ char *fname;
+ fname = (!dentry->d_name.name) ? " " :
+ (char *)dentry->d_name.name;
+ dprintk(EVM_CRYPTO, "%s: %s does not use generic_readlink\n",
+ __FUNCTION__, fname);
+ }
+ if (rbuf_len > 0) {
+ dprintk(EVM_CRYPTO, "%s: link len %d link %s\n",
+ __FUNCTION__, rbuf_len, rbuf);
+
+ sg[0].page = virt_to_page(rbuf);
+ sg[0].offset = ((long)rbuf & ~PAGE_MASK);
+ sg[0].length = rbuf_len;
+
+ crypto_hash_update(desc, sg, rbuf_len);
+ } else
+ error = -EINVAL;
+ return error;
+}
+
+/*
+ * Calculate the MD5/SHA1 digest on a file
+ */
+int evm_calc_hash(struct dentry *dentry, struct file *file, char *digest,
+ int xattr_type)
+{
+ struct crypto_hash *tfm;
+ struct hash_desc desc;
+ int error = 0;
+
+ if (!dentry && !file)
+ return -ENOENT;
+
+ tfm = crypto_alloc_hash(evm_hash, 0, CRYPTO_ALG_ASYNC);
+ if (!tfm) {
+ dprintk(EVM_CRYPTO, "%s: failed to load %s transform\n",
+ __FUNCTION__, evm_hash);
+ return -ENOSYS;
+ }
+ desc.tfm = tfm;
+ desc.flags = 0;
+ crypto_hash_init(&desc);
+
+ if (dentry && S_ISLNK(dentry->d_inode->i_mode))
+ error = update_link_hash(dentry, &desc);
+ else
+ error = update_file_hash(dentry, file, &desc);
+
+ if (!error)
+ crypto_hash_final(&desc, digest);
+
+ crypto_free_hash(tfm);
+ return error;
+}
+
+/*
+ * Calculate the HMAC value for the new file/directory based on the xattr
+ */
+int evm_init_integrity(struct inode *inode, struct inode *dir, char *name,
+ void *value, size_t len, char *digest)
+{
+ struct crypto_hash *tfm;
+ struct scatterlist sg[1];
+ struct hash_desc desc;
+ struct h_misc {
+ unsigned long ino;
+ __u32 generation;
+ } misc, *hmac_misc = &misc;
+ struct evm_xattr_config *config_p;
+
+ tfm = crypto_alloc_hash(evm_hmac, 0, CRYPTO_ALG_ASYNC);
+ if (!tfm) {
+ dprintk(EVM_CRYPTO, "%s: failed to load %s transform\n",
+ __FUNCTION__, evm_hmac);
+ return -ENOSYS;
+ }
+
+ desc.tfm = tfm;
+ desc.flags = 0;
+ crypto_hash_setkey(tfm, tpm_key, tpm_keylen);
+ crypto_hash_init(&desc);
+ for_each_xattr(config_p, evm_config_xattrdata, evm_config_xattrnum) {
+ if (strcmp(config_p->xattr_name + 9, name) == 0) {
+ char *xattr_value = NULL;
+
+ xattr_value = kzalloc(len + 1, GFP_KERNEL);
+ if (!xattr_value) {
+ crypto_free_hash(tfm);
+ return -ENOMEM;
+ }
+ memcpy(xattr_value, value, len);
+ dprintk(EVM_CRYPTO, "%s: (%s) included (%d)\n",
+ __FUNCTION__, config_p->xattr_name, len);
+ sg[0].page = virt_to_page(xattr_value);
+ sg[0].offset = ((long)xattr_value & ~PAGE_MASK);
+ sg[0].length = len;
+ crypto_hash_update(&desc, sg, len);
+ kfree(xattr_value);
+ }
+ }
+ memset(hmac_misc, 0, sizeof misc);
+ hmac_misc->ino = inode->i_ino;
+ hmac_misc->generation = inode->i_generation;
+ sg[0].page = virt_to_page(hmac_misc);
+ sg[0].offset = ((long)hmac_misc & ~PAGE_MASK);
+ sg[0].length = sizeof misc;
+ crypto_hash_update(&desc, sg, sizeof misc);
+ crypto_hash_final(&desc, digest);
+ crypto_free_hash(tfm);
+ return 0;
+}
+
+/*
+ * Calculate the HMAC value across all the extended attributes included
+ * in the HMAC policy as defined in /etc/evm.conf.
+ */
+int evm_calc_hmac(struct dentry *dentry, char *digest)
+{
+ struct inode *inode = dentry->d_inode;
+ struct crypto_hash *tfm;
+ struct hash_desc desc;
+ struct scatterlist sg[1];
+ char *fname;
+ int error = 0;
+
+ struct evm_xattr_config *config_p;
+ int xattr_size = 0;
+ char *xattr_value = NULL;
+
+ struct h_misc {
+ unsigned long ino;
+ __u32 generation;
+ } misc, *hmac_misc = &misc;
+
+ if (!inode->i_op || !inode->i_op->getxattr)
+ return -EOPNOTSUPP;
+
+ /* Load evm_hmac, if not already loaded */
+ tfm = crypto_alloc_hash(evm_hmac, 0, CRYPTO_ALG_ASYNC);
+ if (!tfm) {
+ dprintk(EVM_CRYPTO, "%s: failed to load %s transform\n",
+ __FUNCTION__, evm_hmac);
+ return -ENOSYS;
+ }
+ fname = (!dentry->d_name.name) ? " " : (char *)dentry->d_name.name;
+
+ desc.tfm = tfm;
+ desc.flags = 0;
+ crypto_hash_setkey(tfm, tpm_key, tpm_keylen);
+ crypto_hash_init(&desc);
+
+ /* Get the HMAC policy extended attribute values */
+ for_each_xattr(config_p, evm_config_xattrdata, evm_config_xattrnum) {
+ int size;
+
+ size = inode->i_op->getxattr(dentry, config_p->xattr_name,
+ NULL, 0);
+ if (size < 0)
+ continue;
+ if (size > xattr_size) {
+ kfree(xattr_value);
+ xattr_size = size;
+ xattr_value = kmalloc(xattr_size + 1, GFP_KERNEL);
+ if (!xattr_value) {
+ crypto_free_hash(tfm);
+ return -ENOMEM;
+ }
+ }
+ error = inode->i_op->getxattr(dentry, config_p->xattr_name,
+ xattr_value, xattr_size);
+ if (error > 0) {
+ dprintk(EVM_CRYPTO, "%s: %s(%s) included (%d)\n",
+ __FUNCTION__, fname, config_p->xattr_name,
+ error);
+ sg[0].page = virt_to_page(xattr_value);
+ sg[0].offset = ((long)xattr_value & ~PAGE_MASK);
+ sg[0].length = error;
+ crypto_hash_update(&desc, sg, error);
+ } else {
+ if (strncmp(dentry->d_name.name, "/",
+ dentry->d_name.len) != 0)
+ dprintk(EVM_CRYPTO, "%s: %s(%s) not found\n",
+ __FUNCTION__, fname,
+ config_p->xattr_name);
+ }
+ };
+ kfree(xattr_value);
+ memset(hmac_misc, 0, sizeof misc);
+ hmac_misc->ino = inode->i_ino;
+ hmac_misc->generation = inode->i_generation;
+ sg[0].page = virt_to_page(hmac_misc);
+ sg[0].offset = ((long)hmac_misc & ~PAGE_MASK);
+ sg[0].length = sizeof misc;
+ crypto_hash_update(&desc, sg, sizeof misc);
+ crypto_hash_final(&desc, digest);
+ crypto_free_hash(tfm);
+ return 0;
+}
+
+/*
+ * Calculate and update the hmac, assuming the current hmac is valid.
+ */
+int evm_update_hmac(struct dentry *dentry, int flags)
+{
+ struct inode *inode = dentry->d_inode;
+ struct evm_iint_cache *iint = inode->i_integrity;
+ char hmac_val[MAX_DIGEST_SIZE];
+ int rc = -1;
+
+ if (!evm_install && (iint->hmac_status == INTEGRITY_FAIL)) {
+ dprintk(EVM_BASE, "%s: %s deny update\n",
+ __FUNCTION__, dentry->d_name.name);
+ return -EPERM;
+ }
+
+ memset(hmac_val, 0, sizeof hmac_val);
+ rc = evm_calc_hmac(dentry, hmac_val);
+ dprintk(EVM_CRYPTO, "%s: %s update hmac %d\n",
+ __FUNCTION__, dentry->d_name.name, rc);
+ if (rc == 0) {
+ rc = inode->i_op->setxattr(dentry, evm_hmac_name,
+ hmac_val, evm_hmac_size, flags);
+ iint->hmac_status = INTEGRITY_PASS;
+ }
+ return rc;
+}
+
+/*
+ * Get the key from the TPM for the SHA1-HMAC
+ */
+int evm_init_tpmkernkey(void)
+{
+ struct key *kmk;
+ struct user_key_payload *ukp;
+ int len;
+
+ kmk = request_key(&key_type_user, TPMKEY, NULL);
+ if (IS_ERR(kmk)) {
+ return (-1);
+ } else {
+ down_read(&kmk->sem);
+ ukp = kmk->payload.data;
+ len = ukp->datalen;
+ if (len > MAX_TPMKEY)
+ len = MAX_TPMKEY;
+ tpm_keylen = len;
+ memcpy(tpm_key, ukp->data, len);
+
+ /* burn the original key contents */
+ memset(ukp->data, 0, len);
+ up_read(&kmk->sem);
+ key_put(kmk);
+ return 0;
+ }
+}
Index: linux-2.6.21-rc3-mm2/security/evm/evm.h
===================================================================
--- /dev/null
+++ linux-2.6.21-rc3-mm2/security/evm/evm.h
@@ -0,0 +1,85 @@
+/*
+ * evm.h - extended verification module
+ */
+
+#include <linux/security.h>
+#include <linux/security.h>
+#include <linux/version.h>
+#include <linux/spinlock_types.h>
+#include <linux/integrity.h>
+
+#define DEVFS_SUPER_MAGIC 0x1373
+#define MAX_DIGEST_SIZE 20 /* 160-bits */
+
+extern char *evm_hmac, *evm_hash;
+extern char *evm_hmac_name;
+extern int evm_hmac_size;
+
+extern unsigned int evm_enable_ima;
+/*
+ * EVM configuration policies as defined in /etc/evm.config are
+ * stored in struct evm_config *evm_config_data.
+ */
+enum evm_configtype {
+ EVM_TYPE_MD5, EVM_TYPE_SHA1
+};
+
+struct evm_xattr_config {
+ char xattr_name[XATTR_NAME_MAX + 1];
+};
+
+/*
+ * The extended attribute verification results are memory cached in
+ * inode->i_integrity, preceeded by a header (structure evm_iint_cache),
+ * with the following format:
+ */
+#define EVM_HASH_FIXED 1
+#define EVM_HASH_NONE 2
+
+struct evm_iint_cache {
+ struct timespec mtime;
+ char hash[MAX_DIGEST_SIZE + 1];
+ enum integrity_status hmac_status;
+ enum integrity_status hash_status;
+ int hash_flags; /* no hash, fixed hash */
+ int measured;
+ int hashed;
+ int initialized;
+ struct mutex mutex;
+};
+
+extern void display_config(const char *);
+extern struct evm_xattr_config *evm_parse_config(char *data,
+ unsigned long datalen,
+ int *datasize);
+
+extern int evm_init_config(struct evm_xattr_config *evm_new_data,
+ int evm_new_datasize);
+extern void evm_cleanup_config(void);
+
+extern struct evm_xattr_config *evm_config_xattrdata;
+extern int evm_config_xattrnum; /* number of extended attributes */
+
+#define for_each_xattr(ptr, head, size) \
+ for (ptr = head; ptr < (head + size); ptr++)
+
+extern int evm_init_tpmkernkey(void);
+extern int evm_calc_hash(struct dentry *d, struct file *file,
+ char *digest, int xattrType);
+extern int evm_init_integrity(struct inode *inode, struct inode *dir,
+ char *name, void *value, size_t len,
+ char *digest);
+extern int evm_update_hmac(struct dentry *dentry, int flags);
+extern int evm_calc_hmac(struct dentry *d, char *digest);
+extern int evm_init_secfs(void);
+extern void evm_cleanup_secfs(void);
+
+extern unsigned int evm_debug;
+extern unsigned int evm_install;
+enum evm_debug_level {
+ EVM_BASE = 1, EVM_CACHE = 2, EVM_XATTR = 4, EVM_CRYPTO = 8, EVM_IMA = 16
+};
+
+#define dprintk(level, format, a...) \
+ if (evm_debug & level) \
+ printk(KERN_INFO format, ##a)
Index: linux-2.6.21-rc3-mm2/security/evm/evm_secfs.c
===================================================================
--- /dev/null
+++ linux-2.6.21-rc3-mm2/security/evm/evm_secfs.c
@@ -0,0 +1,201 @@
+/*
+ * evm securityfs support for config and debug control
+ *
+ * Copyright (C) 2005,2006,2007 IBM Corporation
+ * Author: Mimi Zohar <zohar@us.ibm.com>
+ * Kylene Hall <kjhall@us.ibm.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, version 2 of the License.
+ */
+
+#include <asm/uaccess.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/security.h>
+#include <linux/debugfs.h>
+#include "evm.h"
+
+extern int evm_initialized;
+
+static struct dentry *evm_secdir, *evm_config;
+static struct dentry *evm_dir, *evm_cache, *evm_crypto, *evm_xattr;
+
+static int evm_open_debug(struct inode *inode, struct file *file)
+{
+ if (inode->i_private)
+ file->private_data = inode->i_private;
+ return 0;
+}
+
+/*
+ * Once EVM is configured, remove option to update it.
+ */
+static void evm_disable_config(void)
+{
+ securityfs_remove(evm_config);
+ evm_config = NULL;
+ securityfs_remove(evm_secdir);
+ evm_secdir = NULL;
+}
+
+static ssize_t evm_read_debug(struct file *file, char __user * buf,
+ size_t buflen, loff_t * ppos)
+{
+ ssize_t len;
+ char *page;
+
+ page = (char *)__get_free_page(GFP_KERNEL);
+ if (!page)
+ return -ENOMEM;
+
+ if (strcmp(file->private_data, "cache") == 0)
+ len = sprintf(page, "evm_debug: cache: %s\n",
+ ((evm_debug & EVM_CACHE) == EVM_CACHE)
+ ? "ON" : "OFF");
+ else if (strcmp(file->private_data, "xattr") == 0)
+ len = sprintf(page, "evm_debug: xattr: %s\n",
+ ((evm_debug & EVM_XATTR) == EVM_XATTR)
+ ? "ON" : "OFF");
+ else if (strcmp(file->private_data, "crypto") == 0)
+ len = sprintf(page, "evm_debug: crypto: %s\n",
+ ((evm_debug & EVM_CRYPTO) == EVM_CRYPTO)
+ ? "ON" : "OFF");
+ else
+ len = sprintf(page, "unknown evm_debug option\n");
+
+ len = simple_read_from_buffer(buf, buflen, ppos, page, len);
+ free_page((unsigned long)page);
+ return len;
+}
+
+static ssize_t evm_write_debug(struct file *file, const char __user * buf,
+ size_t buflen, loff_t * ppos)
+{
+ char flag;
+
+ if (copy_from_user(&flag, buf, 1))
+ return -EFAULT;
+
+ if (strcmp(file->private_data, "cache") == 0)
+ evm_debug = (flag == '0') ? evm_debug & ~EVM_CACHE :
+ evm_debug | EVM_CACHE;
+ else if (strcmp(file->private_data, "xattr") == 0)
+ evm_debug = (flag == '0') ? evm_debug & ~EVM_XATTR :
+ evm_debug | EVM_XATTR;
+ else if (strcmp(file->private_data, "crypto") == 0)
+ evm_debug = (flag == '0') ? evm_debug & ~EVM_CRYPTO :
+ evm_debug | EVM_CRYPTO;
+ return buflen;
+}
+
+static ssize_t evm_write_secfs(struct file *file, const char __user * buf,
+ size_t buflen, loff_t * ppos)
+{
+ size_t rc = buflen;
+ char *data;
+ int error;
+
+ struct evm_xattr_config *evm_data = NULL;
+ int evm_datasize;
+
+ error = evm_init_tpmkernkey();
+ if (error < 0) {
+ dprintk(EVM_BASE, "%s: tpmkernkey initialization failed \n",
+ __FUNCTION__);
+ return error;
+ } else
+ dprintk(EVM_BASE, "%s: tpmkernkey initialized\n", __FUNCTION__);
+
+ data = kmalloc(buflen + 1, GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ if (copy_from_user(data, buf, buflen)) {
+ kfree(data);
+ return -EFAULT;
+ }
+
+ *(data + buflen) = ' ';
+ evm_data = evm_parse_config(data, buflen, &evm_datasize);
+ if (!evm_data) {
+ kfree(data);
+ return -ENOMEM;
+ }
+
+ if (evm_init_config(evm_data, evm_datasize) < 0) {
+ dprintk(EVM_BASE, "%s: invalid config file\n", __FUNCTION__);
+ rc = -EINVAL;
+ } else {
+ evm_disable_config();
+ evm_initialized = 1;
+ }
+
+ kfree(data);
+ return rc;
+}
+
+static struct file_operations evm_ops = {
+ .write = evm_write_secfs,
+};
+
+static struct file_operations evm_debug_ops = {
+ .read = evm_read_debug,
+ .write = evm_write_debug,
+ .open = evm_open_debug,
+};
+
+int __init evm_init_secfs(void)
+{
+ evm_secdir = securityfs_create_dir("evm", NULL);
+ if (!evm_secdir || IS_ERR(evm_secdir))
+ return -EFAULT;
+
+ evm_config = securityfs_create_file("config",
+ S_IRUSR | S_IRGRP | S_IWUSR,
+ evm_secdir, NULL, &evm_ops);
+ if (!evm_config || IS_ERR(evm_config))
+ goto out_del_secdir;
+ evm_dir = debugfs_create_dir("evm", NULL);
+ if (!evm_dir || IS_ERR(evm_dir))
+ goto out_del_config;
+ evm_cache = debugfs_create_file("cache", S_IRUSR | S_IRGRP,
+ evm_dir, "cache", &evm_debug_ops);
+ if (!evm_cache || IS_ERR(evm_cache))
+ goto out_del_dir;
+ evm_crypto = debugfs_create_file("crypto", S_IRUSR | S_IRGRP, evm_dir,
+ "crypto", &evm_debug_ops);
+ if (!evm_crypto || IS_ERR(evm_crypto))
+ goto out_del_cache;
+
+ evm_xattr = debugfs_create_file("xattr", S_IRUSR | S_IRGRP, evm_dir,
+ "xattr", &evm_debug_ops);
+ if (!evm_xattr || IS_ERR(evm_xattr))
+ goto out_del_crypto;
+ return 0;
+
+out_del_crypto:
+ debugfs_remove(evm_crypto);
+out_del_cache:
+ debugfs_remove(evm_cache);
+out_del_dir:
+ debugfs_remove(evm_dir);
+out_del_config:
+ securityfs_remove(evm_config);
+out_del_secdir:
+ securityfs_remove(evm_secdir);
+ return -EFAULT;
+}
+
+void __exit evm_cleanup_secfs(void)
+{
+ debugfs_remove(evm_xattr);
+ debugfs_remove(evm_crypto);
+ debugfs_remove(evm_cache);
+ debugfs_remove(evm_dir);
+ if (evm_config)
+ securityfs_remove(evm_config);
+ if (evm_secdir)
+ securityfs_remove(evm_secdir);
+}
Index: linux-2.6.21-rc3-mm2/security/evm/Kconfig
===================================================================
--- /dev/null
+++ linux-2.6.21-rc3-mm2/security/evm/Kconfig
@@ -0,0 +1,17 @@
+config INTEGRITY_EVM
+ boolean "EVM support"
+ depends on INTEGRITY && KEYS
+ select CRYPTO_HMAC
+ select CRYPTO_MD5
+ select CRYPTO_SHA1
+ default 0
+ help
+ The Extended Verification Module is an integrity provider.
+ An extensible set of extended attributes, as defined in
+ /etc/evm.conf, are HMAC protected against modification
+ using the TPM's KERNEL ROOT KEY, if configured, or with a
+ pass-phrase. Possible extended attributes include authenticity,
+ integrity, and revision level.
+
+ If you are unsure how to answer this question, answer N.
+
Index: linux-2.6.21-rc3-mm2/security/evm/Makefile
===================================================================
--- /dev/null
+++ linux-2.6.21-rc3-mm2/security/evm/Makefile
@@ -0,0 +1,5 @@
+
+obj-$(CONFIG_INTEGRITY_EVM) += evm.o
+
+evm-y := evm_main.o evm_config.o evm_crypto.o evm_secfs.o
+
Index: linux-2.6.21-rc3-mm2/security/Makefile
===================================================================
--- linux-2.6.21-rc3-mm2.orig/security/Makefile
+++ linux-2.6.21-rc3-mm2/security/Makefile
@@ -13,6 +13,7 @@ endif
# Object file lists
obj-$(CONFIG_SECURITY) += security.o dummy.o inode.o
obj-$(CONFIG_INTEGRITY) += integrity.o integrity_dummy.o
+obj-$(CONFIG_INTEGRITY_EVM) += evm/
# Must precede capability.o in order to stack properly.
obj-$(CONFIG_SECURITY_SLIM) += slim/
obj-$(CONFIG_SECURITY_SELINUX) += selinux/built-in.o
Index: linux-2.6.21-rc3-mm2/security/evm/evm_main.c
===================================================================
--- /dev/null
+++ linux-2.6.21-rc3-mm2/security/evm/evm_main.c
@@ -0,0 +1,926 @@
+/*
+ * EVM - Extended Verification Module
+ *
+ * Copyright (C) 2005,2006,2007 IBM Corporation
+ * Author: Mimi Zohar <zohar@us.ibm.com>
+ * Kylene Hall <kjhall@us.ibm.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, version 2 of the License.
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/notifier.h>
+#include <linux/security.h>
+#include <linux/version.h>
+#include <linux/integrity.h>
+#include <linux/crypto.h>
+#include <linux/init.h>
+#include <linux/proc_fs.h>
+#include <linux/xattr.h>
+#include <linux/file.h>
+#include <linux/writeback.h>
+#include "evm_integrity.h"
+#include "evm.h"
+
+#define MAX_STR_SIZE 40 /* String value */
+#define SHA1_STR_SIZE 40 /* String value */
+#define SHA1_DIGEST_SIZE 20 /* SHA1 is 160-bits */
+
+#define MD5_STR_SIZE 32 /* String value */
+#define MD5_DIGEST_SIZE 16 /* MD5 is 128-bits */
+
+int evm_initialized = 0;
+
+#define FIXED_STR "FIXED"
+#define FIXED_STR_LEN (sizeof (FIXED_STR) -1)
+
+#define XATTR_EVM_SUFFIX "evm."
+#define XATTR_EVM_SUFFIX_LEN (sizeof (XATTR_EVM_SUFFIX) -1)
+
+#define XATTR_MD5_SUFFIX "evm.hash"
+#define XATTR_MD5_SUFFIX_LEN (sizeof (XATTR_MD5_SUFFIX) -1)
+
+#define XATTR_SHA1_SUFFIX "evm.sha1"
+#define XATTR_SHA1_SUFFIX_LEN (sizeof (XATTR_SHA1_SUFFIX) -1)
+
+#define XATTR_HMAC_SUFFIX "evm.hmac"
+#define XATTR_HMAC_SUFFIX_LEN (sizeof (XATTR_HMAC_SUFFIX) -1)
+
+#define XATTR_FLAGS_SUFFIX "evm.flags"
+#define XATTR_FLAGS_SUFFIX_LEN (sizeof (XATTR_FLAGS_SUFFIX) -1)
+
+static int skip_measurement(struct inode *inode, int mask);
+/*
+ * Runtime configuration variables
+ */
+unsigned int evm_debug = EVM_BASE;
+static int __init debug_setup(char *str)
+{
+ evm_debug = simple_strtol(str, NULL, 0);
+ return 1;
+}
+
+__setup("evm_debug=", debug_setup);
+
+char *evm_hmac = "hmac(sha1)"; /* security.evm.hmac default */
+int evm_hmac_size = SHA1_DIGEST_SIZE;
+char *evm_hmac_name = XATTR_SECURITY_PREFIX XATTR_HMAC_SUFFIX;
+static int __init hmac_setup(char *str)
+{
+ evm_hmac = str;
+ return 1;
+}
+
+__setup("evm_hmac=", hmac_setup);
+
+static enum evm_configtype evm_hash_type = EVM_TYPE_MD5;
+char *evm_hash = "md5"; /* security.evm.hash default (~ rpm header) */
+static int hash_str_size = MD5_STR_SIZE;
+static int hash_digest_size = MD5_DIGEST_SIZE;
+static char *evm_hash_name = XATTR_SECURITY_PREFIX XATTR_MD5_SUFFIX;
+static int __init hash_setup(char *str)
+{
+ evm_hash = str;
+ return 1;
+}
+
+__setup("evm_hash=", hash_setup);
+
+unsigned int evm_enable_ima = 1;
+static int __init evm_enable_ima_setup(char *str)
+{
+ evm_enable_ima = simple_strtol(str, NULL, 0);
+ return 1;
+}
+
+__setup("evm_enable_ima=", evm_enable_ima_setup);
+
+unsigned int evm_install = 0;
+static int __init install_mode_setup(char *str)
+{
+ evm_install = simple_strtol(str, NULL, 0);
+ return 1;
+}
+
+__setup("evm_install_mode=", install_mode_setup);
+
+static void hexdump(unsigned char *buf, unsigned int len)
+{
+ while (len--)
+ printk("%02x", *buf++);
+
+ printk("\n");
+}
+
+/*
+ * Compare an extended attribute value with a kernel value
+ */
+ssize_t evm_verify_xattr(struct dentry * dentry, char *kval,
+ char *xattr_name, int size)
+{
+ ssize_t error;
+ char *fname;
+ char *xattr_value;
+ int xattr_size;
+
+ fname = (!dentry->d_name.name) ? " " : (char *)dentry->d_name.name;
+ xattr_size = vfs_getxattr(dentry, xattr_name, NULL, 0);
+ if (xattr_size < 0)
+ return xattr_size;
+
+ xattr_value = kzalloc(xattr_size, GFP_KERNEL);
+ if (!xattr_value) {
+ dprintk(EVM_XATTR, "%s: %s(%s) null xattr_value\n",
+ __FUNCTION__, fname, xattr_name);
+ size = 0;
+ return -ENOMEM;
+ }
+
+ error = vfs_getxattr(dentry, xattr_name, xattr_value, xattr_size);
+ if (error > 0) {
+ if (memcmp(xattr_value, kval, error) != 0) {
+ error = -EINVAL;
+ dprintk(EVM_BASE,
+ "%s: %s(%s) verification failed %d %d\n",
+ __FUNCTION__, fname, xattr_name, size,
+ xattr_size);
+ if (strcmp(xattr_name, "security.evm.hmac") == 0) {
+ hexdump(kval, MAX_DIGEST_SIZE);
+ hexdump(xattr_value, MAX_DIGEST_SIZE);
+ }
+ } else {
+ error = 0;
+ dprintk(EVM_XATTR,
+ "%s: %s(%s) verification succeeded\n",
+ __FUNCTION__, fname, xattr_name);
+ }
+ } else
+ dprintk(EVM_XATTR, "%s: %s(%s) rc = %d no extended attribute\n",
+ __FUNCTION__, fname, xattr_name, error);
+ kfree(xattr_value);
+ return error;
+}
+
+
+/*
+ * The hmac protects against offline attacks. Only new files which do not have
+ * an hmac are acceptable, any other file report as "fail".
+ */
+static int evm_verify_hmac(struct dentry *dentry, struct evm_iint_cache *iint)
+{
+ int rc = 0;
+ char hmac_val[MAX_DIGEST_SIZE];
+ char *fname;
+
+ memset(hmac_val, 0, sizeof hmac_val);
+ rc = evm_calc_hmac(dentry, hmac_val);
+ if (rc < 0)
+ return rc;
+
+ fname = (!dentry->d_name.name) ? " " : (char *)dentry->d_name.name;
+ rc = evm_verify_xattr(dentry, hmac_val, evm_hmac_name, evm_hmac_size);
+ if (rc < 0) {
+ switch (rc) {
+ case -ENODATA: /* file not labelled */
+ case -EINVAL:
+ iint->hmac_status = INTEGRITY_FAIL;
+ dprintk(EVM_BASE, "%s: %s rc = %s\n", __FUNCTION__,
+ fname, rc == -ENODATA ? "ENODATA" : "EINVAL");
+ break;
+ default:
+ dprintk(EVM_CACHE, "%s: %s rc = %d not EOPNOTSUPP, "
+ "ENODATA or EPERM\n", __FUNCTION__, fname, rc);
+ break;
+ }
+ } else {
+ iint->hmac_status = INTEGRITY_PASS;
+ dprintk(EVM_CACHE, "%s: %s HMAC verification succeeeded\n",
+ __FUNCTION__, fname);
+ }
+ iint->initialized = 1;
+ return rc;
+}
+
+/*
+ * Integrity API:
+ * integrity_verify_metadata()
+ * integrity_verify_data()
+ * integrity_measure()
+ */
+static int evm_verify_metadata(struct dentry *dentry, char *xattr_name,
+ char **xattr_value, int *xattr_value_len,
+ int *status)
+{
+ struct inode *inode = dentry->d_inode;
+ struct evm_iint_cache *iint;
+ char *value;
+ int size, error, rc;
+
+ if (!xattr_value || !xattr_value_len || !status)
+ return -EINVAL;
+
+ size = vfs_getxattr(dentry, xattr_name, NULL, 0);
+ if (size < 0) {
+ if (size == -ENODATA) {
+ *status = INTEGRITY_NOLABEL;
+ dprintk(EVM_CACHE, "%s: %s -ENODATA \n",
+ __FUNCTION__, dentry->d_name.name);
+ }
+ return size;
+ }
+ value = kzalloc(size + 1, GFP_KERNEL);
+ if (!value)
+ return -ENOMEM;
+
+ error = vfs_getxattr(dentry, xattr_name, value, size);
+ *xattr_value_len = size;
+ *xattr_value = value;
+
+ if (!evm_initialized)
+ *status = INTEGRITY_PASS;
+ else {
+ iint = inode->i_integrity;
+ mutex_lock(&iint->mutex);
+ if (!iint->initialized &&
+ ((iint->mtime.tv_sec != 0) || S_ISDIR(inode->i_mode)))
+ rc = evm_verify_hmac(dentry, iint);
+ *status = iint->hmac_status;
+ mutex_unlock(&iint->mutex);
+ }
+ return error;
+}
+
+/*
+ * Convert memory to a hex string
+ */
+int mem2hex(char *mem, char *buffer, int count)
+{
+ const char hexchars[] = "0123456789abcdef";
+ int i;
+ char *buf = buffer;
+ int ch;
+
+ memset(buffer, 0, count);
+ for (i = 0; i < count; i++) {
+ ch = (int)*mem++;
+ *buf++ = hexchars[(ch >> 4) & 0xf];
+ *buf++ = hexchars[ch & 0xf];
+ }
+ return (buf - buffer);
+}
+
+enum integrity_status evm_verify_hash(struct dentry *dentry, char *hash)
+{
+ enum integrity_status hash_status;
+ char hash_str[MAX_STR_SIZE + 11];
+ int rc, len;
+
+ len = mem2hex(hash, hash_str, hash_digest_size);
+ rc = evm_verify_xattr(dentry, hash_str, evm_hash_name, hash_str_size);
+
+ if (rc < 0) {
+ switch (rc) {
+ case -EOPNOTSUPP:
+ hash_status = INTEGRITY_PASS;
+ dprintk(EVM_CACHE, "%s: %s -EOPNOTSUPP \n",
+ __FUNCTION__, dentry->d_name.name);
+ break;
+ case -ENODATA: /* file not labelled */
+ hash_status = INTEGRITY_NOLABEL;
+ dprintk(EVM_CACHE, "%s: %s -ENODATA \n",
+ __FUNCTION__, dentry->d_name.name);
+ break;
+ case -EINVAL:
+ default:
+ hash_status = INTEGRITY_FAIL;
+ dprintk(EVM_CACHE, "%s: %s -EINVAL \n",
+ __FUNCTION__, dentry->d_name.name);
+ break;
+ }
+ } else
+ hash_status = INTEGRITY_PASS;
+
+ dprintk(EVM_CACHE, "%s: %s rc %d\n",
+ __FUNCTION__, dentry->d_name.name, rc);
+ return hash_status;
+}
+
+static int evm_verify_data(struct dentry *dentry, int *status)
+{
+ struct inode *inode = dentry->d_inode;
+ struct evm_iint_cache *iint;
+ int rc = 0;
+
+ if (!S_ISREG(inode->i_mode) && !S_ISLNK(inode->i_mode)) {
+ if (status)
+ *status = INTEGRITY_PASS;
+ return 0;
+ }
+ if (!inode->i_op || !inode->i_op->getxattr) {
+ dprintk(EVM_CACHE, "%s: %s no xattr \n",
+ __FUNCTION__, dentry->d_name.name);
+ if (status)
+ *status = INTEGRITY_PASS;
+ return 0;
+ }
+
+ iint = inode->i_integrity;
+ mutex_lock(&iint->mutex);
+ if (!iint->hashed) {
+ enum integrity_status hash_status = INTEGRITY_PASS;
+
+ iint->hashed = 0;
+ rc = evm_calc_hash(dentry, NULL, iint->hash, evm_hash_type);
+ if (rc == 0)
+ hash_status = evm_verify_hash(dentry, iint->hash);
+ iint->hashed = 1;
+ iint->hash_status = hash_status;
+
+ }
+ dprintk(EVM_CACHE, "%s: %s is_hashed status %d\n",
+ __FUNCTION__, dentry->d_name.name, iint->hash_status);
+
+ *status = iint->hash_status;
+ mutex_unlock(&iint->mutex);
+ return rc;
+}
+
+/* what could we exclude
+ * - non-executable/non-library files ?
+ * - /proc /dev ?
+ * Only measure files opened for read-only or execute
+ */
+static int skip_measurement(struct inode *inode, int mask)
+{
+#define SYSFS_MAGIC 0x62656572
+
+ if ((inode->i_sb->s_magic == DEVFS_SUPER_MAGIC) ||
+ (inode->i_sb->s_magic == PROC_SUPER_MAGIC) ||
+ (inode->i_sb->s_magic == SYSFS_MAGIC)) {
+ return 1; /*can't measure */
+ }
+ if (special_file(inode->i_mode) || S_ISLNK(inode->i_mode))
+ return 1; /* don't measure */
+
+ if (S_ISREG(inode->i_mode)
+ && ((mask == MAY_READ) || (mask == MAY_EXEC))
+ && (mask != MAY_WRITE) && (mask != MAY_APPEND))
+ return 0; /* measure */
+ return 1; /* don't measure */
+}
+
+/*
+ * Must be called with the dentry, as opposed to the inode, as we need to be
+ * able to open the file, using dentry_open(), in order to calculate the hash.
+ */
+static void evm_measure(struct dentry *dentry,
+ const unsigned char *filename, int mask)
+{
+ struct inode *inode;
+ struct evm_iint_cache *iint;
+
+ if (!evm_enable_ima)
+ return;
+
+ if (!dentry || !dentry->d_inode) {
+ dprintk(EVM_BASE, "%s: %s null dentry or inode\n",
+ __FUNCTION__, filename);
+ return;
+ }
+
+ inode = dentry->d_inode;
+ if (skip_measurement(inode, mask))
+ return;
+
+ iint = inode->i_integrity;
+ mutex_lock(&iint->mutex);
+ if (!iint->measured) {
+ int rc = 0;
+
+ dprintk(EVM_IMA, "%s: %s not measured\n",
+ __FUNCTION__, filename);
+ if (!iint->hashed) {
+ enum integrity_status hash_status = INTEGRITY_PASS;
+
+ dprintk(EVM_IMA, "%s: %s not hashed\n",
+ __FUNCTION__, filename);
+ rc = evm_calc_hash(dentry, NULL, iint->hash,
+ evm_hash_type);
+ iint->hashed = 1;
+ if (rc == 0)
+ hash_status =
+ evm_verify_hash(dentry, iint->hash);
+ iint->hash_status = hash_status;
+ }
+ evm_ima_measure(filename, SHA1_DIGEST_SIZE, iint->hash);
+ iint->measured = 1;
+ }
+ mutex_unlock(&iint->mutex);
+ return;
+}
+
+static inline void timespec_set(struct timespec *to, struct timespec *from)
+{
+ to->tv_sec = from->tv_sec;
+ to->tv_nsec = from->tv_nsec;
+}
+
+/*
+ * HMAC the initial extended attribute from security_inode_init_security.
+ */
+static void evm_inode_init_hmac(struct inode *inode, struct inode *dir,
+ char **name, void **value, size_t * len)
+{
+ char *hmac_name = XATTR_HMAC_SUFFIX;
+ char hmac_val[MAX_DIGEST_SIZE];
+ struct evm_iint_cache *iint = inode->i_integrity;
+
+ /* Indicate a new file */
+ mutex_lock(&iint->mutex);
+ iint->mtime.tv_sec = 0;
+ iint->hmac_status = INTEGRITY_NOLABEL;
+
+ if (!evm_initialized) { /* Can't calc hmac yet. */
+ mutex_unlock(&iint->mutex);
+ return;
+ }
+
+ if (!name || !value || !len) {
+ mutex_unlock(&iint->mutex);
+ return;
+ }
+
+ memset(hmac_val, 0, sizeof hmac_val);
+ evm_init_integrity(inode, dir, *name, *value, *len, hmac_val);
+
+ *name = kstrdup(hmac_name, GFP_KERNEL);
+ *len = MAX_DIGEST_SIZE;
+ *value = kmalloc(*len, GFP_KERNEL);
+ memcpy(*value, hmac_val, *len);
+
+ mutex_unlock(&iint->mutex);
+ return;
+}
+
+/*
+ * For a process to modify any "security.evm." extended attributes
+ * included in the "security.evm.hmac", as defined in /etc/evm.config,
+ * the process must have system admin capabilities. The ability to
+ * modify other extended attributes included in the hmac, are assumed
+ * to be controlled by the concerned kernel module's inode_setxattr().
+ * For example, slim permits a process to write the "security.slim.level"
+ * extended attribute up to the process' integrity level.
+ */
+int evm_inode_setxattr(struct dentry *dentry, char *name, void *value,
+ size_t size, int flags)
+{
+ int error = 0;
+ struct evm_xattr_config *config_p;
+ char *xattr_flags = XATTR_SECURITY_PREFIX XATTR_FLAGS_SUFFIX;
+ int xattr_flags_len =XATTR_SECURITY_PREFIX_LEN + XATTR_FLAGS_SUFFIX_LEN;
+ char *xattr_evm = XATTR_SECURITY_PREFIX XATTR_EVM_SUFFIX;
+ int xattr_evm_len = XATTR_SECURITY_PREFIX_LEN + XATTR_EVM_SUFFIX_LEN;
+
+ if (!evm_initialized) /* Can't calc hmac yet. */
+ return 0;
+
+ if (!name || !value) {
+ printk(KERN_INFO "%s: name | value is null \n", __FUNCTION__);
+ return -EINVAL;
+ }
+
+ for_each_xattr(config_p, evm_config_xattrdata, evm_config_xattrnum) {
+ if (strncmp(name, config_p->xattr_name, strlen(name)) != 0)
+ continue;
+
+ if ((!capable(CAP_SYS_ADMIN)) && (evm_install)) {
+ if ((strncmp(name, XATTR_SECURITY_PREFIX,
+ XATTR_SECURITY_PREFIX_LEN) != 0))
+ error = -EPERM;
+ } else if ((!capable(CAP_SYS_ADMIN))
+ && (strncmp(name, xattr_evm, xattr_evm_len) == 0))
+ error = -EPERM;
+ else if (strncmp(name, xattr_flags, xattr_flags_len) == 0) {
+ struct inode *inode = dentry->d_inode;
+ struct evm_iint_cache *iint;
+
+ iint = inode->i_integrity;
+ mutex_lock(&iint->mutex);
+ if (strncmp(value, FIXED_STR, FIXED_STR_LEN) == 0)
+ iint->hash_flags |= EVM_HASH_FIXED;
+ else
+ iint->hash_flags |= EVM_HASH_NONE;
+ mutex_unlock(&iint->mutex);
+ }
+ break;
+ }
+ dprintk(EVM_XATTR, "%s: %s %s(%d - %s)\n", __FUNCTION__,
+ (!dentry->d_name.name) ? " " : (char *)dentry->d_name.
+ name, error == 0 ? "succeeded" : "failed", error, name);
+ return error;
+}
+
+/*
+ * After updating/removing an extended attribute defined in /etc/evm.config,
+ * calculate and save the new hmac, assuming the current hmac is valid.
+ */
+void evm_inode_hmacxattr(struct dentry *dentry, char *name)
+{
+ struct evm_xattr_config *config_p;
+
+ if (!evm_initialized) /* Can't calc hmac yet. */
+ return;
+
+ for_each_xattr(config_p, evm_config_xattrdata, evm_config_xattrnum) {
+ if (strncmp(name, config_p->xattr_name, strlen(name)) == 0) {
+ struct inode *inode = dentry->d_inode;
+ struct evm_iint_cache *iint=inode->i_integrity;
+ int rc = 0;
+
+ mutex_lock(&iint->mutex);
+ rc = evm_update_hmac(dentry, 0);
+ mutex_unlock(&iint->mutex);
+ dprintk(EVM_XATTR, "%s: %s hmac calc %s\n",
+ __FUNCTION__, (!dentry->d_name.name)
+ ? " " : (char *)dentry->d_name.name,
+ rc == 0 ? "succeeded" : "failed");
+ break;
+ }
+ }
+}
+
+/*
+ * Write an extended attribute included in /etc/evm.conf and update
+ * the security.evm.hmac, assuming the current hmac is valid.
+ */
+static int evm_setxattr(struct dentry *dentry, char *name, void *value,
+ size_t size, int flags)
+{
+ struct evm_xattr_config *config_p;
+ int rc = -1;
+
+ if (!evm_initialized) /* Can't calc hmac yet. */
+ return 0;
+
+ if (!value || !name)
+ return -EINVAL;
+
+ if (!dentry->d_inode || !dentry->d_inode->i_op) {
+ dprintk(EVM_XATTR, "%s: dentry->d_inode or ->i_op is null \n",
+ __FUNCTION__);
+ return -EINVAL;
+ }
+
+ if (!dentry->d_inode->i_op->setxattr) {
+ dprintk(EVM_XATTR, "%s: i_op->setxattr is null \n",
+ __FUNCTION__);
+ return -EOPNOTSUPP;
+ }
+
+ /*
+ * Must use setxattr directly, as vfs_setxattr calls
+ * integrity_inode_setxattr, which prevents processes without
+ * CAP_SYS_ADMIN from updating security.evm.XXXX extended attributes.
+ */
+ for_each_xattr(config_p, evm_config_xattrdata, evm_config_xattrnum) {
+ if (strncmp(name, config_p->xattr_name, strlen(name)) == 0) {
+ rc = dentry->d_inode->i_op->setxattr(dentry, name,
+ value, size,
+ flags);
+ if (!rc)
+ rc = evm_update_hmac(dentry, flags);
+
+ break;
+ }
+ }
+ return rc;
+}
+
+/*
+ * Convert the hash value to a string and write out the hash extended attribute,
+ * assuming the file hash is not fixed (immutable) or the file should be
+ * unhashed.
+ *
+ * Call with iint->i_mutex locked.
+ */
+static void evm_set_hashxattr(struct dentry *dentry, char *hash)
+{
+ struct inode *inode = dentry->d_inode;
+ struct evm_iint_cache *iint;
+ char hash_str[MAX_STR_SIZE + 11];
+ int len, rc;
+
+ iint = inode->i_integrity;
+
+ if ((iint->hash_flags & EVM_HASH_FIXED) == EVM_HASH_FIXED) {
+ enum integrity_status hash_status;
+
+ hash_status = evm_verify_hash(dentry, iint->hash);
+ if (hash_status != INTEGRITY_PASS) {
+ iint->hash_status = INTEGRITY_FAIL;
+ dprintk(EVM_CACHE, "%s: %s - hash changed\n",
+ __FUNCTION__, dentry->d_name.name);
+ }
+ return;
+ } else if ((iint->hash_flags & EVM_HASH_NONE) == EVM_HASH_NONE) {
+ dprintk(EVM_CACHE, "%s: %s - no hash\n",
+ __FUNCTION__, dentry->d_name.name);
+ return;
+ }
+
+ len = mem2hex(hash, hash_str, hash_digest_size);
+ dprintk(EVM_CACHE, "%s: flags %d len %d %32s\n", __FUNCTION__,
+ iint->hash_flags, len, hash_str);
+ rc = evm_setxattr(dentry, evm_hash_name, hash_str, len, 0);
+ iint->hash_status = INTEGRITY_PASS;
+
+ return;
+}
+
+/*
+ * Calculate the new hash and update the extended attribute.
+ * Called with iint->i_mutex locked.
+ */
+static void evm_update_hash(struct file *file)
+{
+ mode_t sav_fmode;
+ struct inode *inode = file->f_dentry->d_inode;
+ struct evm_iint_cache *iint;
+ int rc;
+
+ sav_fmode = file->f_mode;
+ file->f_mode |= FMODE_READ;
+
+ iint = inode->i_integrity;
+ iint->measured = 0;
+ iint->hashed = 0;
+ rc = evm_calc_hash(NULL, file, iint->hash, evm_hash_type);
+ iint->hashed = 1;
+
+ file->f_mode = sav_fmode;
+ if (rc == 0)
+ evm_set_hashxattr(file->f_dentry, iint->hash);
+}
+
+/*
+ * When files are opened/closed in quick succession, the mtime
+ * might not be granular enough, resulting in the mtime remaining
+ * unchanged.
+ *
+ * Use to prevent changes from not being detected.
+ */
+static inline int timespec_recent(struct timespec *a)
+{
+ return CURRENT_TIME.tv_sec - a->tv_sec <= 1 ? 1 : 0;
+}
+
+/*
+ * Called on close
+ * - Except for fixed hash(immutable), no hash, or invalid integrity files,
+ * update the evm.hash extended attribute value and reflect the change in
+ * the hmac.
+ */
+static void evm_file_free(struct file *file)
+{
+ struct inode *inode = NULL;
+ struct evm_iint_cache *iint;
+
+ if (!file->f_dentry) /* can be NULL */
+ return;
+
+ inode = file->f_dentry->d_inode;
+ if (S_ISDIR(inode->i_mode))
+ return;
+ if ((file->f_mode & FMODE_WRITE) &&
+ (atomic_read(&inode->i_writecount) == 1)) {
+ iint = inode->i_integrity;
+ mutex_lock(&iint->mutex);
+ if ((!timespec_equal(&iint->mtime, &inode->i_mtime))
+ || timespec_recent(&iint->mtime)) {
+ evm_update_hash(file);
+ timespec_set(&iint->mtime, &inode->i_mtime);
+ iint->measured = 0;
+ }
+ mutex_unlock(&iint->mutex);
+ }
+}
+
+static struct evm_iint_cache *evm_alloc_integrity(void)
+{
+ struct evm_iint_cache *iint;
+
+ iint = kzalloc(sizeof(struct evm_iint_cache), GFP_KERNEL);
+ if (!iint)
+ return NULL;
+
+ mutex_init(&iint->mutex);
+ return iint;
+}
+
+static int evm_inode_alloc_integrity(struct inode *inode)
+{
+ struct evm_iint_cache *iint;
+
+ iint = evm_alloc_integrity();
+ if (!iint)
+ return -ENOMEM;
+
+ inode->i_integrity = iint;
+ timespec_set(&iint->mtime, &inode->i_mtime);
+ return 0;
+}
+
+static void evm_inode_free_integrity(struct inode *inode)
+{
+ struct evm_iint_cache *iint = inode->i_integrity;
+
+ if (iint){
+ inode->i_integrity = NULL; /* XXXX */
+ kfree(iint);
+ }
+}
+
+/*
+ * Initialize the flags field based on the security.evm.flags extended
+ * attribute, which contains either "FIXED" or "UNHASHED". The FIXED flags
+ * value indicates the file is immutable and that the hash should never
+ * be updated. The UNHASHED flags value indicates that the file should
+ * never be hashed.
+ */
+static void evm_update_hashflags(struct dentry *dentry,
+ struct evm_iint_cache *iint)
+{
+ ssize_t error;
+ char *xattr_flags = XATTR_SECURITY_PREFIX XATTR_FLAGS_SUFFIX;
+ char *xattr_value;
+ int xattr_size;
+
+ xattr_size = vfs_getxattr(dentry, xattr_flags, NULL, 0);
+ if (xattr_size < 0)
+ return;
+
+ xattr_value = kzalloc(xattr_size, GFP_KERNEL);
+ if (!xattr_value)
+ return;
+
+ error = vfs_getxattr(dentry, xattr_flags, xattr_value, xattr_size);
+ if (error > 0) {
+ if (strncmp(xattr_value, FIXED_STR, FIXED_STR_LEN) == 0)
+ iint->hash_flags |= EVM_HASH_FIXED;
+ else
+ iint->hash_flags |= EVM_HASH_NONE;
+ }
+ kfree(xattr_value);
+}
+
+/*
+ * Verify the integrity of the hmac and reflect the result in
+ * iint->hmac_status.
+ *
+ * Exception: new_inodes defined as mtime == 0
+ */
+static void evm_d_instantiate(struct dentry *dentry, struct inode *inode)
+{
+ struct evm_iint_cache *iint;
+ ssize_t error;
+
+ if (!evm_initialized) /* Can't calc hmac yet. */
+ return;
+
+ if (!inode)
+ return;
+
+ if (!inode->i_op || !inode->i_op->getxattr)
+ return;
+
+ iint = inode->i_integrity;
+ mutex_lock(&iint->mutex);
+ if (!iint->initialized) {
+ if ((iint->mtime.tv_sec != 0) || S_ISDIR(inode->i_mode))
+ error = evm_verify_hmac(dentry, iint);
+ evm_update_hashflags(dentry, iint);
+ }
+ mutex_unlock(&iint->mutex);
+}
+
+/*
+ * For all inodes allocate inode->i_integrity(iint), before the integrity
+ * subsystem is enabled.
+ */
+static void evm_fixup_inodes(void)
+{
+ struct super_block *sb;
+
+ spin_lock(&sb_lock);
+ list_for_each_entry(sb, &super_blocks, s_list) {
+ struct inode *inode;
+
+ spin_unlock(&sb_lock);
+
+ spin_lock(&inode_lock);
+ list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
+ spin_unlock(&inode_lock);
+
+ spin_lock(&inode->i_lock);
+ if (!inode->i_integrity)
+ evm_inode_alloc_integrity(inode);
+ spin_unlock(&inode->i_lock);
+
+ spin_lock(&inode_lock);
+ }
+ spin_unlock(&inode_lock);
+
+ spin_lock(&sb_lock);
+ }
+ spin_unlock(&sb_lock);
+}
+
+static struct integrity_operations evm_integrity_ops = {
+ .verify_metadata = evm_verify_metadata,
+ .verify_data = evm_verify_data,
+ .measure = evm_measure,
+ .inode_init_integrity = evm_inode_init_hmac,
+ .inode_setxattr = evm_inode_setxattr,
+ .inode_post_setxattr = evm_inode_hmacxattr,
+ .inode_alloc_integrity = evm_inode_alloc_integrity,
+ .inode_free_integrity = evm_inode_free_integrity,
+ .file_free_integrity = evm_file_free,
+ .d_instantiate = evm_d_instantiate
+};
+
+static struct integrity_operations evm_install_ops = {
+ .inode_post_setxattr = evm_inode_hmacxattr,
+ .inode_alloc_integrity = evm_inode_alloc_integrity,
+ .inode_free_integrity = evm_inode_free_integrity
+};
+
+static void evm_enable_integrity(void)
+{
+ if (evm_install) {
+ register_integrity(&evm_install_ops);
+ dprintk(EVM_BASE, "%s: Enabled EVM install mode\n",
+ __FUNCTION__);
+ } else
+ register_integrity(&evm_integrity_ops);
+}
+
+static void evm_cleanup_integrity(void)
+{
+ if (evm_install) {
+ unregister_integrity(&evm_install_ops);
+ } else
+ unregister_integrity(&evm_integrity_ops);
+}
+
+static struct crypto_hash *tfm_hash, *tfm_hmac; /* preload crypto alg */
+static int __init init_evm(void)
+{
+ int error;
+
+ if (strncmp(evm_hash, "sha1", 4) == 0) {
+ evm_hash_type = EVM_TYPE_SHA1;
+ hash_digest_size = SHA1_DIGEST_SIZE;
+ hash_str_size = SHA1_STR_SIZE;
+ evm_hash_name = XATTR_SECURITY_PREFIX XATTR_SHA1_SUFFIX;
+ }
+ tfm_hash = crypto_alloc_hash(evm_hash, 0, CRYPTO_ALG_ASYNC);
+ tfm_hmac = crypto_alloc_hash(evm_hmac, 0, CRYPTO_ALG_ASYNC);
+
+ error = evm_init_secfs();
+ if (error < 0)
+ dprintk(EVM_BASE, "%s: Error registering secfs|debugfs\n",
+ __FUNCTION__);
+
+ error = evm_ima_init();
+ if (error < 0)
+ dprintk(EVM_BASE, "%s: Error enabling ima\n",
+ __FUNCTION__);
+ evm_fixup_inodes();
+ evm_enable_integrity();
+
+ return error;
+}
+
+static void __exit cleanup_evm(void)
+{
+ evm_cleanup_secfs();
+ evm_cleanup_config();
+ evm_cleanup_integrity();
+ evm_ima_cleanup();
+ crypto_free_hash(tfm_hash);
+ crypto_free_hash(tfm_hmac);
+ dprintk(EVM_BASE, "%s: %s completed\n", __FUNCTION__,
+ evm_install ? "install mode" : "");
+}
+
+late_initcall(init_evm);
+module_exit(cleanup_evm);
+
+MODULE_DESCRIPTION("Extended Verification Module");
+MODULE_LICENSE("GPL");
Index: linux-2.6.21-rc3-mm2/security/Kconfig
===================================================================
--- linux-2.6.21-rc3-mm2.orig/security/Kconfig
+++ linux-2.6.21-rc3-mm2/security/Kconfig
@@ -46,6 +46,7 @@ config INTEGRITY
configured into your kernel.

If you are unsure how to answer this question, answer N.
+source security/evm/Kconfig

config SECURITY
bool "Enable different security models"
Index: linux-2.6.21-rc3-mm2/fs/namei.c
===================================================================
--- linux-2.6.21-rc3-mm2.orig/fs/namei.c
+++ linux-2.6.21-rc3-mm2/fs/namei.c
@@ -2616,6 +2616,27 @@ int generic_readlink(struct dentry *dent
return PTR_ERR(cookie);
}

+int kernel_readlink(struct dentry *dentry, char **buffer, int *buflen)
+{
+ struct nameidata nd;
+ void *cookie;
+
+ nd.depth = 0;
+ cookie = dentry->d_inode->i_op->follow_link(dentry, &nd);
+ if (!IS_ERR(cookie)) {
+ char *link;
+
+ link = nd_get_link(&nd);
+ if (IS_ERR(link))
+ return PTR_ERR(link);
+ *buffer = kstrdup(link, GFP_KERNEL);
+ *buflen = (*buffer == NULL) ? 0 : strlen(*buffer);
+ if (dentry->d_inode->i_op->put_link)
+ dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
+ }
+ return PTR_ERR(cookie);
+}
+
int vfs_follow_link(struct nameidata *nd, const char *link)
{
return __vfs_follow_link(nd, link);
@@ -2758,6 +2779,7 @@ EXPORT_SYMBOL(vfs_mkdir);
EXPORT_SYMBOL(vfs_mknod);
EXPORT_SYMBOL(generic_permission);
EXPORT_SYMBOL(vfs_readlink);
+EXPORT_SYMBOL(kernel_readlink);
EXPORT_SYMBOL(vfs_rename);
EXPORT_SYMBOL(vfs_rmdir);
EXPORT_SYMBOL(vfs_symlink);


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