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Date: Mon, 2 Feb 2009 17:02:11 -0600
From: "Serge E. Hallyn" <serge@...lyn.com>
To: Mimi Zohar <zohar@...ux.vnet.ibm.com>
Cc: linux-kernel@...r.kernel.org,
Andrew Morton <akpm@...ux-foundation.org>,
James Morris <jmorris@...ei.org>,
Christoph Hellwig <hch@...radead.org>,
Dave Hansen <dave@...ux.vnet.ibm.com>,
"<David Safford" <safford@...son.ibm.com>,
Serge Hallyn <serue@...ibm.com>, Mimi Zohar <zohar@...ibm.com>
Subject: Re: [PATCH 2/6] integrity: IMA as an integrity service provider
Quoting Mimi Zohar (zohar@...ux.vnet.ibm.com):
> IMA provides hardware (TPM) based measurement and attestation for
> file measurements. As the Trusted Computing (TPM) model requires,
> IMA measures all files before they are accessed in any way (on the
> integrity_bprm_check, integrity_path_check and integrity_file_mmap
> hooks), and commits the measurements to the TPM. Once added to the
> TPM, measurements can not be removed.
>
> In addition, IMA maintains a list of these file measurements, which
> can be used to validate the aggregate value stored in the TPM. The
> TPM can sign these measurements, and thus the system can prove, to
> itself and to a third party, the system's integrity in a way that
> cannot be circumvented by malicious or compromised software.
>
> - removed LIM hooks and API registration; IMA is now called directly
> - added slab for integrity information(iint) associated with an inode
> - added a local read and write count in iint
> - lots of code refactoring (i.e. calculating the boot aggregate,
> flagging openwriters/ToMToU)
> - statically defined and initialized variables
> - addressed the credential merge changes
> - addressed locking issues in general (i.e. ima_file_free())
> and addressed the rcu-locking problem in ima_iint_delete() in particular
> - removed caching of measurement policy results
> - removed Kconfig prompt for: pcr index, informational audit messages
>
> Signed-off-by: Mimi Zohar <zohar@...ibm.com>
I notice there is no MAINTAINERS entry for IMA?
A few comments below. Aside from my comments in ima_bprm_check and
ima_path_check,
Acked-by: Serge Hallyn <serue@...ibm.com>
> ---
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index 40c51e9..8cc40a1 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -901,6 +901,15 @@ and is between 256 and 4096 characters. It is defined in the file
> ihash_entries= [KNL]
> Set number of hash buckets for inode cache.
>
> + ima_audit= [IMA]
> + Format: { "0" | "1" }
> + 0 -- integrity auditing messages. (Default)
> + 1 -- enable informational integrity auditing messages.
> +
> + ima_hash= [IMA]
> + Formt: { "sha1" | "md5" }
> + default: "sha1"
> +
> in2000= [HW,SCSI]
> See header of drivers/scsi/in2000.c.
>
> diff --git a/include/linux/audit.h b/include/linux/audit.h
> index 67e5dbf..930939a 100644
> --- a/include/linux/audit.h
> +++ b/include/linux/audit.h
> @@ -125,6 +125,11 @@
> #define AUDIT_LAST_KERN_ANOM_MSG 1799
> #define AUDIT_ANOM_PROMISCUOUS 1700 /* Device changed promiscuous mode */
> #define AUDIT_ANOM_ABEND 1701 /* Process ended abnormally */
> +#define AUDIT_INTEGRITY_DATA 1800 /* Data integrity verification */
> +#define AUDIT_INTEGRITY_METADATA 1801 /* Metadata integrity verification */
> +#define AUDIT_INTEGRITY_STATUS 1802 /* Integrity enable status */
> +#define AUDIT_INTEGRITY_HASH 1803 /* Integrity HASH type */
> +#define AUDIT_INTEGRITY_PCR 1804 /* PCR invalidation msgs */
>
> #define AUDIT_KERNEL 2000 /* Asynchronous audit record. NOT A REQUEST. */
>
> diff --git a/include/linux/ima.h b/include/linux/ima.h
> index 4ed1e4d..dcc3664 100644
> --- a/include/linux/ima.h
> +++ b/include/linux/ima.h
> @@ -12,6 +12,15 @@
> #ifndef _LINUX_IMA_H
> #define _LINUX_IMA_H
>
> +#ifdef CONFIG_IMA
> +extern int ima_bprm_check(struct linux_binprm *bprm);
> +extern int ima_inode_alloc(struct inode *inode);
> +extern void ima_inode_free(struct inode *inode);
> +extern int ima_path_check(struct path *path, int mask);
> +extern void ima_file_free(struct file *file);
> +extern int ima_file_mmap(struct file *file, unsigned long prot);
> +
> +#else
> static inline int ima_bprm_check(struct linux_binprm *bprm)
> {
> return 0;
> @@ -41,4 +50,5 @@ static inline int ima_file_mmap(struct file *file, unsigned long prot)
> {
> return 0;
> }
> +#endif /* CONFIG_IMA_H */
> #endif /* _LINUX_IMA_H */
> diff --git a/security/Kconfig b/security/Kconfig
> index 9438535..bf129f8 100644
> --- a/security/Kconfig
> +++ b/security/Kconfig
> @@ -55,7 +55,8 @@ config SECURITYFS
> bool "Enable the securityfs filesystem"
> help
> This will build the securityfs filesystem. It is currently used by
> - the TPM bios character driver. It is not used by SELinux or SMACK.
> + the TPM bios character driver and IMA, an integrity provider. It is
> + not used by SELinux or SMACK.
>
> If you are unsure how to answer this question, answer N.
>
> @@ -135,5 +136,7 @@ config SECURITY_DEFAULT_MMAP_MIN_ADDR
> source security/selinux/Kconfig
> source security/smack/Kconfig
>
> +source security/integrity/ima/Kconfig
> +
> endmenu
>
> diff --git a/security/Makefile b/security/Makefile
> index c05c127..595536c 100644
> --- a/security/Makefile
> +++ b/security/Makefile
> @@ -17,3 +17,7 @@ obj-$(CONFIG_SECURITY_SELINUX) += selinux/built-in.o
> obj-$(CONFIG_SECURITY_SMACK) += smack/built-in.o
> obj-$(CONFIG_SECURITY_ROOTPLUG) += root_plug.o
> obj-$(CONFIG_CGROUP_DEVICE) += device_cgroup.o
> +
> +# Object integrity file lists
> +subdir-$(CONFIG_IMA) += integrity/ima
> +obj-$(CONFIG_IMA) += integrity/ima/built-in.o
> diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
> new file mode 100644
> index 0000000..2a761c8
> --- /dev/null
> +++ b/security/integrity/ima/Kconfig
> @@ -0,0 +1,49 @@
> +# IBM Integrity Measurement Architecture
> +#
> +config IMA
> + bool "Integrity Measurement Architecture(IMA)"
> + depends on ACPI
> + select SECURITYFS
> + select CRYPTO
> + select CRYPTO_HMAC
> + select CRYPTO_MD5
> + select CRYPTO_SHA1
> + select TCG_TPM
> + select TCG_TIS
> + help
> + The Trusted Computing Group(TCG) runtime Integrity
> + Measurement Architecture(IMA) maintains a list of hash
> + values of executables and other sensitive system files,
> + as they are read or executed. If an attacker manages
> + to change the contents of an important system file
> + being measured, we can tell.
> +
> + If your system has a TPM chip, then IMA also maintains
> + an aggregate integrity value over this list inside the
> + TPM hardware, so that the TPM can prove to a third party
> + whether or not critical system files have been modified.
> + Read <http://www.usenix.org/events/sec04/tech/sailer.html>
> + to learn more about IMA.
> + If unsure, say N.
> +
> +config IMA_MEASURE_PCR_IDX
> + int
> + depends on IMA
> + range 8 14
> + default 10
> + help
> + IMA_MEASURE_PCR_IDX determines the TPM PCR register index
> + that IMA uses to maintain the integrity aggregate of the
> + measurement list. If unsure, use the default 10.
> +
> +config IMA_AUDIT
> + bool
> + depends on IMA
> + default y
> + help
> + This option adds a kernel parameter 'ima_audit', which
> + allows informational auditing messages to be enabled
> + at boot. If this option is selected, informational integrity
> + auditing messages can be enabled with 'ima_audit=1' on
> + the kernel command line.
> +
> diff --git a/security/integrity/ima/Makefile b/security/integrity/ima/Makefile
> new file mode 100644
> index 0000000..9d6bf97
> --- /dev/null
> +++ b/security/integrity/ima/Makefile
> @@ -0,0 +1,9 @@
> +#
> +# Makefile for building Trusted Computing Group's(TCG) runtime Integrity
> +# Measurement Architecture(IMA).
> +#
> +
> +obj-$(CONFIG_IMA) += ima.o
> +
> +ima-y := ima_queue.o ima_init.o ima_main.o ima_crypto.o ima_api.o \
> + ima_policy.o ima_iint.o ima_audit.o
> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
> new file mode 100644
> index 0000000..04a397e
> --- /dev/null
> +++ b/security/integrity/ima/ima.h
> @@ -0,0 +1,136 @@
> +/*
> + * Copyright (C) 2005,2006,2007,2008 IBM Corporation
> + *
> + * Authors:
> + * Reiner Sailer <sailer@...son.ibm.com>
> + * Mimi Zohar <zohar@...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.
> + *
> + * File: ima.h
> + * internal Integrity Measurement Architecture (IMA) definitions
> + */
> +
> +#ifndef __LINUX_IMA_H
> +#define __LINUX_IMA_H
> +
> +#include <linux/types.h>
> +#include <linux/crypto.h>
> +#include <linux/security.h>
> +#include <linux/hash.h>
> +#include <linux/tpm.h>
> +#include <linux/audit.h>
> +
> +enum ima_show_type { IMA_SHOW_BINARY, IMA_SHOW_ASCII };
> +enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8 };
> +
> +/* digest size for IMA, fits SHA1 or MD5 */
> +#define IMA_DIGEST_SIZE 20
> +#define IMA_EVENT_NAME_LEN_MAX 255
> +
> +#define IMA_HASH_BITS 9
> +#define IMA_MEASURE_HTABLE_SIZE (1 << IMA_HASH_BITS)
> +
> +/* set during initialization */
> +extern int ima_initialized;
> +extern int ima_used_chip;
> +extern char *ima_hash;
> +
> +/* IMA inode template definition */
> +struct ima_template_data {
> + u8 digest[IMA_DIGEST_SIZE]; /* sha1/md5 measurement hash */
> + char file_name[IMA_EVENT_NAME_LEN_MAX + 1]; /* name + \0 */
> +};
> +
> +#define IMA_TEMPLATE_NAME_LEN_MAX 20
No longer used
> +struct ima_template_entry {
> + u8 digest[IMA_DIGEST_SIZE]; /* sha1 or md5 measurement hash */
> + char *template_name;
> + int template_len;
> + struct ima_template_data template;
> +};
> +
> +struct ima_queue_entry {
> + struct hlist_node hnext; /* place in hash collision list */
> + struct list_head later; /* place in ima_measurements list */
> + struct ima_template_entry *entry;
> +};
> +extern struct list_head ima_measurements; /* list of all measurements */
> +
> +/* declarations */
> +void integrity_audit_msg(int audit_msgno, struct inode *inode,
> + const unsigned char *fname, const char *op,
> + const char *cause, int result, int info);
> +
> +/* Internal IMA function definitions */
> +void ima_iintcache_init(void);
> +int ima_init(void);
> +int ima_add_template_entry(struct ima_template_entry *entry, int violation,
> + const char *op, struct inode *inode);
> +int ima_calc_hash(struct file *file, char *digest);
> +int ima_calc_template_hash(int template_len, void *template, char *digest);
> +int ima_calc_boot_aggregate(char *digest);
> +void ima_add_violation(struct inode *inode, const unsigned char *filename,
> + const char *op, const char *cause);
> +
> +/*
> + * used to protect h_table and sha_table
> + */
> +extern spinlock_t ima_queue_lock;
> +
> +struct ima_h_table {
> + atomic_long_t len; /* number of stored measurements in the list */
> + atomic_long_t violations;
> + struct hlist_head queue[IMA_MEASURE_HTABLE_SIZE];
> +};
> +extern struct ima_h_table ima_htable;
> +
> +static inline unsigned long ima_hash_key(u8 *digest)
> +{
> + return hash_long(*digest, IMA_HASH_BITS);
> +}
> +
> +/* iint cache flags */
> +#define IMA_MEASURED 1
> +
> +/* integrity data associated with an inode */
> +struct ima_iint_cache {
> + u64 version; /* track inode changes */
> + unsigned long flags;
> + u8 digest[IMA_DIGEST_SIZE];
> + struct mutex mutex; /* protects: version, flags, digest */
> + long readcount; /* measured files readcount */
> + long writecount; /* measured files writecount */
> + struct kref refcount; /* ima_iint_cache reference count */
> + struct rcu_head rcu;
> +};
> +
> +/* LIM API function definitions */
> +int ima_must_measure(struct ima_iint_cache *iint, struct inode *inode,
> + int mask, int function);
> +int ima_collect_measurement(struct ima_iint_cache *iint, struct file *file);
> +void ima_store_measurement(struct ima_iint_cache *iint, struct file *file,
> + const unsigned char *filename);
> +int ima_store_template(struct ima_template_data *data, int violation,
> + struct inode *inode);
> +
> +/* radix tree calls to lookup, insert, delete
> + * integrity data associated with an inode.
> + */
> +struct ima_iint_cache *ima_iint_insert(struct inode *inode);
> +struct ima_iint_cache *ima_iint_find_get(struct inode *inode);
> +struct ima_iint_cache *ima_iint_find_insert_get(struct inode *inode);
> +void ima_iint_delete(struct inode *inode);
> +void iint_free(struct kref *kref);
> +void iint_rcu_free(struct rcu_head *rcu);
> +
> +/* IMA policy related functions */
> +enum ima_hooks { PATH_CHECK = 1, FILE_MMAP, BPRM_CHECK };
> +
> +int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask);
> +void ima_init_policy(void);
> +void ima_update_policy(void);
> +#endif
> diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
> new file mode 100644
> index 0000000..7c1db11
> --- /dev/null
> +++ b/security/integrity/ima/ima_api.c
> @@ -0,0 +1,185 @@
> +/*
> + * Copyright (C) 2008 IBM Corporation
> + *
> + * Author: Mimi Zohar <zohar@...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.
> + *
> + * File: ima_api.c
> + * Implements must_measure, collect_measurement, store_measurement,
> + * and store_template.
> + */
> +#include <linux/module.h>
> +
> +#include "ima.h"
> +static char *IMA_TEMPLATE_NAME = "ima";
> +
> +/*
> + * ima_store_template - store ima template measurements
> + *
> + * Calculate the hash of a template entry, add the template entry
> + * to an ordered list of measurement entries maintained inside the kernel,
> + * and also update the aggregate integrity value (maintained inside the
> + * configured TPM PCR) over the hashes of the current list of measurement
> + * entries.
> + *
> + * Applications retrieve the current kernel-held measurement list through
> + * the securityfs entries in /sys/kernel/security/ima. The signed aggregate
> + * TPM PCR (called quote) can be retrieved using a TPM user space library
> + * and is used to validate the measurement list.
> + *
> + * Returns 0 on success, error code otherwise
> + */
> +int ima_store_template(struct ima_template_data *template,
> + int violation, struct inode *inode)
> +{
> + struct ima_template_entry *entry;
> + const char *op = "add_template_measure";
> + const char *audit_cause = "ENOMEM";
> + int result = -ENOMEM;
> +
> + entry = kmalloc(sizeof(*entry), GFP_KERNEL);
> + if (!entry)
> + goto err_out;
> +
> + memcpy(&entry->template, template, sizeof(*template));
> + memset(&entry->digest, 0, sizeof(entry->digest));
> + entry->template_name = IMA_TEMPLATE_NAME;
> + entry->template_len = sizeof(*template);
> +
> + if (!violation) {
> + result = ima_calc_template_hash(entry->template_len,
> + template, entry->digest);
> + if (result < 0) {
> + kfree(entry);
> + audit_cause = "hashing_error";
> + goto err_out;
> + }
> + }
> + result = ima_add_template_entry(entry, violation, op, inode);
> + if (result < 0)
> + kfree(entry);
> + return result;
> +
> +err_out:
> + integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, entry->template_name,
> + op, audit_cause, result, 0);
> +
> + return result;
> +}
> +
> +/*
> + * ima_add_violation - add violation to measurement list.
> + *
> + * Violations are flagged in the measurement list with zero hash values.
> + * By extending the PCR with 0xFF's instead of with zeroes, the PCR
> + * value is invalidated.
> + */
> +void ima_add_violation(struct inode *inode, const unsigned char *filename,
> + const char *op, const char *cause)
> +{
> + struct ima_template_data template;
> + int violation = 1;
> + int result;
> +
> + /* can overflow, only indicator */
> + atomic_long_inc(&ima_htable.violations);
> +
> + memset(&template, 0, sizeof(template));
> + strncpy(template.file_name, filename, IMA_EVENT_NAME_LEN_MAX);
> + result = ima_store_template(&template, violation, inode);
> + integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
> + op, cause, result, 0);
> +}
> +
> +/**
> + * ima_must_measure - measure decision based on policy.
> + * @inode: pointer to inode to measure
> + * @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXECUTE)
> + * @function: calling function (PATH_CHECK, BPRM_CHECK, FILE_MMAP)
> + *
> + * The policy is defined in terms of keypairs:
> + * subj=, obj=, type=, func=, mask=, fsmagic=
> + * subj,obj, and type: are LSM specific.
> + * func: PATH_CHECK | BPRM_CHECK | FILE_MMAP
> + * mask: contains the permission mask
> + * fsmagic: hex value
> + *
> + * Must be called with iint->mutex held.
> + *
> + * Return 0 to measure. Return 1 if already measured.
> + * For matching a DONT_MEASURE policy, no policy, or other
> + * error, return an error code.
> +*/
> +int ima_must_measure(struct ima_iint_cache *iint, struct inode *inode,
> + int mask, int function)
> +{
> + int must_measure;
> +
> + if (iint->flags & IMA_MEASURED)
> + return 1;
> +
> + must_measure = ima_match_policy(inode, function, mask);
> + return must_measure ? 0 : -EACCES;
> +}
> +
> +/*
> + * ima_collect_measurement - collect file measurement
> + *
> + * Calculate the file hash, if it doesn't already exist,
> + * storing the measurement and i_version in the iint.
> + *
> + * Must be called with iint->mutex held.
> + *
> + * Return 0 on success, error code otherwise
> + */
> +int ima_collect_measurement(struct ima_iint_cache *iint, struct file *file)
> +{
> + int result = -EEXIST;
> +
> + if (!(iint->flags & IMA_MEASURED)) {
> + u64 i_version = file->f_dentry->d_inode->i_version;
> +
> + memset(iint->digest, 0, IMA_DIGEST_SIZE);
> + result = ima_calc_hash(file, iint->digest);
> + if (!result)
> + iint->version = i_version;
> + }
> + return result;
> +}
> +
> +/*
> + * ima_store_measurement - store file measurement
> + *
> + * Create an "ima" template and then store the template by calling
> + * ima_store_template.
> + *
> + * We only get here if the inode has not already been measured,
> + * but the measurement could already exist:
> + * - multiple copies of the same file on either the same or
> + * different filesystems.
> + * - the inode was previously flushed as well as the iint info,
> + * containing the hashing info.
> + *
> + * Must be called with iint->mutex held.
> + */
> +void ima_store_measurement(struct ima_iint_cache *iint, struct file *file,
> + const unsigned char *filename)
> +{
> +
> + struct inode *inode = file->f_dentry->d_inode;
> + struct ima_template_data template;
> + int violation = 0;
> + int result;
> +
> + memset(&template, 0, sizeof(template));
> + memcpy(template.digest, iint->digest, IMA_DIGEST_SIZE);
> + strncpy(template.file_name, filename, IMA_EVENT_NAME_LEN_MAX);
> +
> + result = ima_store_template(&template, violation, inode);
Is there any advantage to copying the data onto the
stack here and passing that to ima_store_template(),
instead of just kmallocing a ima_template_entry right
here, just filling in the digest and file_name, and
passing those to iam_store_template()?
> + if (!result)
> + iint->flags |= IMA_MEASURED;
> +}
> diff --git a/security/integrity/ima/ima_audit.c b/security/integrity/ima/ima_audit.c
> new file mode 100644
> index 0000000..8a0f1e2
> --- /dev/null
> +++ b/security/integrity/ima/ima_audit.c
> @@ -0,0 +1,78 @@
> +/*
> + * Copyright (C) 2008 IBM Corporation
> + * Author: Mimi Zohar <zohar@...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.
> + *
> + * File: integrity_audit.c
> + * Audit calls for the integrity subsystem
> + */
> +
> +#include <linux/fs.h>
> +#include <linux/audit.h>
> +#include "ima.h"
> +
> +static int ima_audit;
> +
> +#ifdef CONFIG_IMA_AUDIT
> +
> +/* ima_audit_setup - enable informational auditing messages */
> +static int __init ima_audit_setup(char *str)
> +{
> + unsigned long audit;
> + int rc;
> + char *op;
> +
> + rc = strict_strtoul(str, 0, &audit);
> + if (rc || audit > 1)
> + printk(KERN_INFO "ima: invalid ima_audit value\n");
> + else
> + ima_audit = audit;
> + op = ima_audit ? "ima_audit_enabled" : "ima_audit_not_enabled";
> + integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL, NULL, op, 0, 0);
> + return 1;
> +}
> +__setup("ima_audit=", ima_audit_setup);
> +#endif
> +
> +void integrity_audit_msg(int audit_msgno, struct inode *inode,
> + const unsigned char *fname, const char *op,
> + const char *cause, int result, int audit_info)
> +{
> + struct audit_buffer *ab;
> +
> + if (!ima_audit && audit_info == 1) /* Skip informational messages */
> + return;
> +
> + ab = audit_log_start(current->audit_context, GFP_KERNEL, audit_msgno);
> + audit_log_format(ab, "integrity: pid=%d uid=%u auid=%u",
> + current->pid, current->cred->uid,
> + audit_get_loginuid(current));
> + audit_log_task_context(ab);
> + switch (audit_msgno) {
> + case AUDIT_INTEGRITY_DATA:
> + case AUDIT_INTEGRITY_METADATA:
> + case AUDIT_INTEGRITY_PCR:
> + audit_log_format(ab, " op=%s cause=%s", op, cause);
> + break;
> + case AUDIT_INTEGRITY_HASH:
> + audit_log_format(ab, " op=%s hash=%s", op, cause);
> + break;
> + case AUDIT_INTEGRITY_STATUS:
> + default:
> + audit_log_format(ab, " op=%s", op);
> + }
> + audit_log_format(ab, " comm=");
> + audit_log_untrustedstring(ab, current->comm);
> + if (fname) {
> + audit_log_format(ab, " name=");
> + audit_log_untrustedstring(ab, fname);
> + }
> + if (inode)
> + audit_log_format(ab, " dev=%s ino=%lu",
> + inode->i_sb->s_id, inode->i_ino);
> + audit_log_format(ab, " res=%d", result);
> + audit_log_end(ab);
> +}
> diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
> new file mode 100644
> index 0000000..c2a46e4
> --- /dev/null
> +++ b/security/integrity/ima/ima_crypto.c
> @@ -0,0 +1,140 @@
> +/*
> + * Copyright (C) 2005,2006,2007,2008 IBM Corporation
> + *
> + * Authors:
> + * Mimi Zohar <zohar@...ibm.com>
> + * Kylene Hall <kjhall@...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.
> + *
> + * File: ima_crypto.c
> + * Calculates md5/sha1 file hash, template hash, boot-aggreate hash
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/file.h>
> +#include <linux/crypto.h>
> +#include <linux/scatterlist.h>
> +#include <linux/err.h>
> +#include "ima.h"
> +
> +static int init_desc(struct hash_desc *desc)
> +{
> + int rc;
> +
> + desc->tfm = crypto_alloc_hash(ima_hash, 0, CRYPTO_ALG_ASYNC);
> + if (IS_ERR(desc->tfm)) {
> + pr_info("failed to load %s transform: %ld\n",
> + ima_hash, PTR_ERR(desc->tfm));
> + rc = PTR_ERR(desc->tfm);
> + return rc;
> + }
> + desc->flags = 0;
> + rc = crypto_hash_init(desc);
> + if (rc)
> + crypto_free_hash(desc->tfm);
> + return rc;
> +}
> +
> +/*
> + * Calculate the MD5/SHA1 file digest
> + */
> +int ima_calc_hash(struct file *file, char *digest)
> +{
> + struct hash_desc desc;
> + struct scatterlist sg[1];
> + loff_t i_size;
> + char *rbuf;
> + int rc, offset = 0;
> +
> + rc = init_desc(&desc);
> + if (rc != 0)
> + return rc;
> +
> + rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL);
> + if (!rbuf) {
> + rc = -ENOMEM;
> + goto out;
> + }
> + i_size = i_size_read(file->f_dentry->d_inode);
> + while (offset < i_size) {
> + int rbuf_len;
> +
> + rbuf_len = kernel_read(file, offset, rbuf, PAGE_SIZE);
> + if (rbuf_len < 0) {
> + rc = rbuf_len;
> + break;
> + }
> + offset += rbuf_len;
> + sg_set_buf(sg, rbuf, rbuf_len);
> +
> + rc = crypto_hash_update(&desc, sg, rbuf_len);
> + if (rc)
> + break;
> + }
> + kfree(rbuf);
> + if (!rc)
> + rc = crypto_hash_final(&desc, digest);
> +out:
> + crypto_free_hash(desc.tfm);
> + return rc;
> +}
> +
> +/*
> + * Calculate the hash of a given template
> + */
> +int ima_calc_template_hash(int template_len, void *template, char *digest)
> +{
> + struct hash_desc desc;
> + struct scatterlist sg[1];
> + int rc;
> +
> + rc = init_desc(&desc);
> + if (rc != 0)
> + return rc;
> +
> + sg_set_buf(sg, template, template_len);
> + rc = crypto_hash_update(&desc, sg, template_len);
> + if (!rc)
> + rc = crypto_hash_final(&desc, digest);
> + crypto_free_hash(desc.tfm);
> + return rc;
> +}
> +
> +static void ima_pcrread(int idx, u8 *pcr)
> +{
> + if (!ima_used_chip)
> + return;
> +
> + if (tpm_pcr_read(TPM_ANY_NUM, idx, pcr) != 0)
> + pr_err("Error Communicating to TPM chip\n");
> +}
> +
> +/*
> + * Calculate the boot aggregate hash
> + */
> +int ima_calc_boot_aggregate(char *digest)
> +{
> + struct hash_desc desc;
> + struct scatterlist sg;
> + u8 pcr_i[IMA_DIGEST_SIZE];
> + int rc, i;
> +
> + rc = init_desc(&desc);
> + if (rc != 0)
> + return rc;
> +
> + /* cumulative sha1 over tpm registers 0-7 */
(Just out of curiosity) why? Are these the ones the BIOS and grub
will use by convention?
> + for (i = TPM_PCR0; i < TPM_PCR8; i++) {
> + ima_pcrread(i, pcr_i);
> + /* now accumulate with current aggregate */
> + sg_init_one(&sg, pcr_i, IMA_DIGEST_SIZE);
> + rc = crypto_hash_update(&desc, &sg, IMA_DIGEST_SIZE);
> + }
> + if (!rc)
> + crypto_hash_final(&desc, digest);
> + crypto_free_hash(desc.tfm);
> + return rc;
> +}
> diff --git a/security/integrity/ima/ima_iint.c b/security/integrity/ima/ima_iint.c
> new file mode 100644
> index 0000000..750db3c
> --- /dev/null
> +++ b/security/integrity/ima/ima_iint.c
> @@ -0,0 +1,185 @@
> +/*
> + * Copyright (C) 2008 IBM Corporation
> + *
> + * Authors:
> + * Mimi Zohar <zohar@...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.
> + *
> + * File: ima_iint.c
> + * - implements the IMA hooks: ima_inode_alloc, ima_inode_free
> + * - cache integrity information associated with an inode
> + * using a radix tree.
> + */
> +#include <linux/module.h>
> +#include <linux/spinlock.h>
> +#include <linux/radix-tree.h>
> +#include "ima.h"
> +
> +#define ima_iint_delete ima_inode_free
> +
> +RADIX_TREE(ima_iint_store, GFP_ATOMIC);
> +DEFINE_SPINLOCK(ima_iint_lock);
> +
> +static struct kmem_cache *iint_cache __read_mostly;
> +
> +/* ima_iint_find_get - return the iint associated with an inode
> + *
> + * ima_iint_find_get gets a reference to the iint. Caller must
> + * remember to put the iint reference.
> + */
> +struct ima_iint_cache *ima_iint_find_get(struct inode *inode)
> +{
> + struct ima_iint_cache *iint;
> +
> + rcu_read_lock();
> + iint = radix_tree_lookup(&ima_iint_store, (unsigned long)inode);
> + if (!iint)
> + goto out;
> + kref_get(&iint->refcount);
> +out:
> + rcu_read_unlock();
> + return iint;
> +}
> +
> +/* Allocate memory for the iint associated with the inode
> + * from the iint_cache slab, initialize the iint, and
> + * insert it into the radix tree.
> + *
> + * On success return a pointer to the iint; on failure return NULL.
> + */
> +struct ima_iint_cache *ima_iint_insert(struct inode *inode)
> +{
> + struct ima_iint_cache *iint = NULL;
> + int rc = 0;
> +
> + if (!ima_initialized)
> + return iint;
> + iint = kmem_cache_alloc(iint_cache, GFP_KERNEL);
> + if (!iint)
> + return iint;
> +
> + rc = radix_tree_preload(GFP_KERNEL);
> + if (rc < 0)
> + goto out;
> +
> + spin_lock(&ima_iint_lock);
> + rc = radix_tree_insert(&ima_iint_store, (unsigned long)inode, iint);
> + spin_unlock(&ima_iint_lock);
> +out:
> + if (rc < 0) {
> + kmem_cache_free(iint_cache, iint);
> + if (rc == -EEXIST) {
> + iint = radix_tree_lookup(&ima_iint_store,
> + (unsigned long)inode);
> + } else
> + iint = NULL;
> + }
> + radix_tree_preload_end();
> + return iint;
> +}
> +
> +/**
> + * ima_inode_alloc - allocate an iint associated with an inode
> + * @inode: pointer to the inode
> + *
> + * Return 0 on success, 1 on failure.
> + */
> +int ima_inode_alloc(struct inode *inode)
> +{
> + struct ima_iint_cache *iint;
> +
> + if (!ima_initialized)
> + return 0;
> +
> + iint = ima_iint_insert(inode);
> + if (!iint)
> + return 1;
> + return 0;
> +}
> +
> +/* ima_iint_find_insert_get - get the iint associated with an inode
> + *
> + * Most insertions are done at inode_alloc, except those allocated
> + * before late_initcall. When the iint does not exist, allocate it,
> + * initialize and insert it, and increment the iint refcount.
> + *
> + * (Can't initialize at security_initcall before any inodes are
> + * allocated, got to wait at least until proc_init.)
> + *
> + * Return the iint.
> + */
> +struct ima_iint_cache *ima_iint_find_insert_get(struct inode *inode)
> +{
> + struct ima_iint_cache *iint = NULL;
> +
> + iint = ima_iint_find_get(inode);
> + if (iint)
> + return iint;
> +
> + iint = ima_iint_insert(inode);
> + if (iint)
> + kref_get(&iint->refcount);
> +
> + return iint;
> +}
> +
> +/* iint_free - called when the iint refcount goes to zero */
> +void iint_free(struct kref *kref)
> +{
> + struct ima_iint_cache *iint = container_of(kref, struct ima_iint_cache,
> + refcount);
> + iint->version = 0;
> + iint->flags = 0UL;
> + kref_set(&iint->refcount, 1);
> + kmem_cache_free(iint_cache, iint);
> +}
> +
> +void iint_rcu_free(struct rcu_head *rcu_head)
> +{
> + struct ima_iint_cache *iint = container_of(rcu_head,
> + struct ima_iint_cache, rcu);
> + kref_put(&iint->refcount, iint_free);
> +}
> +
> +/**
> + * ima_iint_delete - called on integrity_inode_free
> + * @inode: pointer to the inode
> + *
> + * Free the integrity information(iint) associated with an inode.
> + */
> +void ima_iint_delete(struct inode *inode)
> +{
> + struct ima_iint_cache *iint;
> +
> + if (!ima_initialized)
> + return;
> + spin_lock(&ima_iint_lock);
> + iint = radix_tree_delete(&ima_iint_store, (unsigned long)inode);
> + spin_unlock(&ima_iint_lock);
> + if (iint)
> + call_rcu(&iint->rcu, iint_rcu_free);
> +}
> +
> +static void init_once(void *foo)
> +{
> + struct ima_iint_cache *iint = foo;
> +
> + memset(iint, 0, sizeof *iint);
> + iint->version = 0;
> + iint->flags = 0UL;
> + mutex_init(&iint->mutex);
> + iint->readcount = 0;
> + iint->writecount = 0;
> + kref_set(&iint->refcount, 1);
> +}
> +
> +void ima_iintcache_init(void)
> +{
> + iint_cache =
> + kmem_cache_create("iint_cache", sizeof(struct ima_iint_cache), 0,
> + SLAB_PANIC, init_once);
> +}
> diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c
> new file mode 100644
> index 0000000..e681a40
> --- /dev/null
> +++ b/security/integrity/ima/ima_init.c
> @@ -0,0 +1,73 @@
> +/*
> + * Copyright (C) 2005,2006,2007,2008 IBM Corporation
> + *
> + * Authors:
> + * Reiner Sailer <sailer@...son.ibm.com>
> + * Leendert van Doorn <leendert@...son.ibm.com>
> + * Mimi Zohar <zohar@...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.
> + *
> + * File: ima_init.c
> + * initialization and cleanup functions
> + */
> +#include <linux/module.h>
> +#include <linux/scatterlist.h>
> +#include <linux/err.h>
> +#include "ima.h"
> +
> +/* name for boot aggregate entry */
> +static char *boot_aggregate_name = "boot_aggregate";
> +int ima_used_chip;
> +
> +/* Add the boot aggregate to the IMA measurement list and extend
> + * the PCR register.
> + *
> + * Calculate the boot aggregate, a SHA1 over tpm registers 0-7,
> + * assuming a TPM chip exists, and zeroes if the TPM chip does not
> + * exist. Add the boot aggregate measurement to the measurement
> + * list and extend the PCR register.
> + *
> + * If a tpm chip does not exist, indicate the core root of trust is
> + * not hardware based by invalidating the aggregate PCR value.
> + * (The aggregate PCR value is invalidated by adding one value to
> + * the measurement list and extending the aggregate PCR value with
> + * a different value.) Violations add a zero entry to the measurement
> + * list and extend the aggregate PCR value with ff...ff's.
> + */
> +static void ima_add_boot_aggregate(void)
> +{
> + struct ima_template_data template;
> + int violation = 1;
> + int result;
> +
> + memset(&template, 0, sizeof(template));
> + strncpy(template.file_name, boot_aggregate_name,
> + IMA_EVENT_NAME_LEN_MAX);
> +
> + if (ima_used_chip) {
> + violation = 0;
> + ima_calc_boot_aggregate(template.digest);
You're ignoring the return value of ima_calc_boot_aggregate...
> + }
> + result = ima_store_template(&template, violation, NULL);
...and effectively ignoring result?
I realize it shouldn't ever matter...
> +}
> +
> +int ima_init(void)
> +{
> + int rc;
> +
> + ima_used_chip = 0;
> + rc = tpm_pcr_read(TPM_ANY_NUM, 0, NULL);
> + if (rc == 0)
> + ima_used_chip = 1;
> +
> + if (!ima_used_chip)
> + pr_info("No TPM chip found, activating TPM-bypass!\n");
> +
> + ima_add_boot_aggregate(); /* boot aggregate must be first entry */
> + ima_init_policy();
> + return 0;
> +}
> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> new file mode 100644
> index 0000000..53cee4c
> --- /dev/null
> +++ b/security/integrity/ima/ima_main.c
> @@ -0,0 +1,280 @@
> +/*
> + * Copyright (C) 2005,2006,2007,2008 IBM Corporation
> + *
> + * Authors:
> + * Reiner Sailer <sailer@...son.ibm.com>
> + * Serge Hallyn <serue@...ibm.com>
> + * Kylene Hall <kylene@...ibm.com>
> + * Mimi Zohar <zohar@...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.
> + *
> + * File: ima_main.c
> + * implements the IMA hooks: ima_bprm_check, ima_file_mmap,
> + * and ima_path_check.
> + */
> +#include <linux/module.h>
> +#include <linux/file.h>
> +#include <linux/binfmts.h>
> +#include <linux/mount.h>
> +#include <linux/mman.h>
> +
> +#include "ima.h"
> +
> +int ima_initialized;
> +
> +char *ima_hash = "sha1";
> +static int __init hash_setup(char *str)
> +{
> + const char *op = "hash_setup";
> + const char *hash = "sha1";
> + int result = 0;
> + int audit_info = 0;
> +
> + if (strncmp(str, "md5", 3) == 0) {
> + hash = "md5";
> + ima_hash = str;
> + } else if (strncmp(str, "sha1", 4) != 0) {
> + hash = "invalid_hash_type";
> + result = 1;
> + }
> + integrity_audit_msg(AUDIT_INTEGRITY_HASH, NULL, NULL, op, hash,
> + result, audit_info);
> + return 1;
> +}
> +__setup("ima_hash=", hash_setup);
> +
> +/**
> + * ima_file_free - called on __fput()
> + * @file: pointer to file structure being freed
> + *
> + * Flag files that changed, based on i_version;
> + * and decrement the iint readcount/writecount.
> + */
> +void ima_file_free(struct file *file)
> +{
> + struct inode *inode = file->f_dentry->d_inode;
> + struct ima_iint_cache *iint;
> +
> + if (!ima_initialized || !S_ISREG(inode->i_mode))
> + return;
> + iint = ima_iint_find_get(inode);
> + if (!iint)
> + return;
> +
> + mutex_lock(&iint->mutex);
> + if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
> + iint->readcount--;
> +
> + if (file->f_mode & FMODE_WRITE) {
> + iint->writecount--;
> + if (iint->writecount == 0) {
> + if (iint->version != inode->i_version)
> + iint->flags &= ~IMA_MEASURED;
> + }
> + }
> + mutex_unlock(&iint->mutex);
> + kref_put(&iint->refcount, iint_free);
> +}
> +
> +/* ima_read_write_check - reflect possible reading/writing errors in the PCR.
> + *
> + * When opening a file for read, if the file is already open for write,
> + * the file could change, resulting in a file measurement error.
> + *
> + * Opening a file for write, if the file is already open for read, results
> + * in a time of measure, time of use (ToMToU) error.
> + *
> + * In either case invalidate the PCR.
> + */
> +enum iint_pcr_error { TOMTOU, OPEN_WRITERS };
> +static void ima_read_write_check(enum iint_pcr_error error,
> + struct ima_iint_cache *iint,
> + struct inode *inode,
> + const unsigned char *filename)
> +{
> + switch (error) {
> + case TOMTOU:
> + if (iint->readcount > 0)
> + ima_add_violation(inode, filename, "invalid_pcr",
> + "ToMToU");
> + break;
> + case OPEN_WRITERS:
> + if (iint->writecount > 0)
> + ima_add_violation(inode, filename, "invalid_pcr",
> + "open_writers");
> + break;
> + }
> +}
> +
> +static int get_path_measurement(struct ima_iint_cache *iint, struct file *file,
> + const unsigned char *filename)
> +{
> + int rc = 0;
> +
> + if (IS_ERR(file)) {
> + pr_info("%s dentry_open failed\n", filename);
> + return rc;
> + }
> + iint->readcount++;
> +
> + rc = ima_collect_measurement(iint, file);
> + if (!rc)
> + ima_store_measurement(iint, file, filename);
> + return rc;
> +}
> +
> +/**
> + * ima_path_check - based on policy, collect/store measurement.
> + * @path: contains a pointer to the path to be measured
> + * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
> + *
> + * Measure the file being open for readonly, based on the
> + * ima_must_measure() policy decision.
> + *
> + * Keep read/write counters for all files, but only
> + * invalidate the PCR for measured files:
> + * - Opening a file for write when already open for read,
> + * results in a time of measure, time of use (ToMToU) error.
> + * - Opening a file for read when already open for write,
> + * could result in a file measurement error.
> + *
> + * Return 0 on success, an error code on failure.
> + * (Based on the results of appraise_measurement().)
> + */
> +int ima_path_check(struct path *path, int mask)
> +{
> + struct inode *inode = path->dentry->d_inode;
> + struct ima_iint_cache *iint;
> + struct file *file = NULL;
> + int rc;
> +
> + if (!ima_initialized || !S_ISREG(inode->i_mode))
> + return 0;
> + iint = ima_iint_find_insert_get(inode);
> + if (!iint)
> + return 0;
> +
> + mutex_lock(&iint->mutex);
> + if ((mask & MAY_WRITE) || (mask == 0))
> + iint->writecount++;
> + else if (mask & (MAY_READ | MAY_EXEC))
> + iint->readcount++;
> +
> + rc = ima_must_measure(iint, inode, MAY_READ, PATH_CHECK);
why MAY_READ, if mask could have MAY_WRITE?
> + if (rc < 0)
> + goto out;
> +
> + if ((mask & MAY_WRITE) || (mask == 0))
> + ima_read_write_check(TOMTOU, iint, inode,
> + path->dentry->d_name.name);
> +
> + if ((mask & (MAY_WRITE | MAY_READ | MAY_EXEC)) != MAY_READ)
> + goto out;
> +
> + ima_read_write_check(OPEN_WRITERS, iint, inode,
> + path->dentry->d_name.name);
> + if (!(iint->flags & IMA_MEASURED)) {
> + struct dentry *dentry = dget(path->dentry);
> + struct vfsmount *mnt = mntget(path->mnt);
> +
> + file = dentry_open(dentry, mnt, O_RDONLY, current->cred);
> + rc = get_path_measurement(iint, file, dentry->d_name.name);
> + }
> +out:
> + mutex_unlock(&iint->mutex);
> + if (file)
> + fput(file);
> + kref_put(&iint->refcount, iint_free);
> + return 0;
> +}
> +
> +static int process_measurement(struct file *file, const unsigned char *filename,
> + int mask, int function)
> +{
> + struct inode *inode = file->f_dentry->d_inode;
> + struct ima_iint_cache *iint;
> + int rc;
> +
> + if (!ima_initialized || !S_ISREG(inode->i_mode))
> + return 0;
> + iint = ima_iint_find_insert_get(inode);
> + if (!iint)
> + return -ENOMEM;
> +
> + mutex_lock(&iint->mutex);
> + rc = ima_must_measure(iint, inode, mask, function);
> + if (rc != 0)
> + goto out;
> +
> + rc = ima_collect_measurement(iint, file);
> + if (!rc)
> + ima_store_measurement(iint, file, filename);
> +out:
> + mutex_unlock(&iint->mutex);
> + kref_put(&iint->refcount, iint_free);
> + return rc;
> +}
> +
> +/**
> + * ima_file_mmap - based on policy, collect/store measurement.
> + * @file: pointer to the file to be measured (May be NULL)
> + * @prot: contains the protection that will be applied by the kernel.
> + *
> + * Measure files being mmapped executable based on the ima_must_measure()
> + * policy decision.
> + *
> + * Return 0 on success, an error code on failure.
> + * (Based on the results of appraise_measurement().)
> + */
> +int ima_file_mmap(struct file *file, unsigned long prot)
> +{
> + int rc;
> +
> + if (!file)
> + return 0;
> + if (prot & PROT_EXEC)
> + rc = process_measurement(file, file->f_dentry->d_name.name,
> + MAY_EXEC, FILE_MMAP);
> + return 0;
> +}
> +
> +/**
> + * ima_bprm_check - based on policy, collect/store measurement.
> + * @bprm: contains the linux_binprm structure
> + *
> + * The OS protects against an executable file, already open for write,
> + * from being executed in deny_write_access() and an executable file,
> + * already open for execute, from being modified in get_write_access().
> + * So we can be certain that what we verify and measure here is actually
> + * what is being executed.
> + *
> + * Return 0 on success, an error code on failure.
> + * (Based on the results of appraise_measurement().)
> + */
> +int ima_bprm_check(struct linux_binprm *bprm)
> +{
> + int rc;
> +
> + rc = process_measurement(bprm->file, bprm->filename,
> + MAY_EXEC, BPRM_CHECK);
> + return 0;
?
> +}
> +
> +static int __init init_ima(void)
> +{
> + int error;
> +
> + ima_iintcache_init();
> + error = ima_init();
> + ima_initialized = 1;
> + return error;
> +}
> +
> +late_initcall(init_ima); /* Start IMA after the TPM is available */
> +
> +MODULE_DESCRIPTION("Integrity Measurement Architecture");
> +MODULE_LICENSE("GPL");
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> new file mode 100644
> index 0000000..7c3d1ff
> --- /dev/null
> +++ b/security/integrity/ima/ima_policy.c
> @@ -0,0 +1,126 @@
> +/*
> + * Copyright (C) 2008 IBM Corporation
> + * Author: Mimi Zohar <zohar@...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.
> + *
> + * ima_policy.c
> + * - initialize default measure policy rules
> + *
> + */
> +#include <linux/module.h>
> +#include <linux/list.h>
> +#include <linux/audit.h>
> +#include <linux/security.h>
> +#include <linux/magic.h>
> +
> +#include "ima.h"
> +
> +/* flags definitions */
> +#define IMA_FUNC 0x0001
> +#define IMA_MASK 0x0002
> +#define IMA_FSMAGIC 0x0004
> +#define IMA_UID 0x0008
> +
> +enum ima_action { DONT_MEASURE, MEASURE };
> +
> +struct ima_measure_rule_entry {
> + struct list_head list;
> + enum ima_action action;
> + unsigned int flags;
> + enum ima_hooks func;
> + int mask;
> + unsigned long fsmagic;
> + uid_t uid;
> +};
> +
> +static struct ima_measure_rule_entry default_rules[] = {
> + {.action = DONT_MEASURE,.fsmagic = PROC_SUPER_MAGIC,
> + .flags = IMA_FSMAGIC},
> + {.action = DONT_MEASURE,.fsmagic = SYSFS_MAGIC,.flags = IMA_FSMAGIC},
> + {.action = DONT_MEASURE,.fsmagic = DEBUGFS_MAGIC,.flags = IMA_FSMAGIC},
> + {.action = DONT_MEASURE,.fsmagic = TMPFS_MAGIC,.flags = IMA_FSMAGIC},
> + {.action = DONT_MEASURE,.fsmagic = SECURITYFS_MAGIC,
> + .flags = IMA_FSMAGIC},
> + {.action = DONT_MEASURE,.fsmagic = 0xF97CFF8C,.flags = IMA_FSMAGIC},
> + {.action = MEASURE,.func = FILE_MMAP,.mask = MAY_EXEC,
> + .flags = IMA_FUNC | IMA_MASK},
> + {.action = MEASURE,.func = BPRM_CHECK,.mask = MAY_EXEC,
> + .flags = IMA_FUNC | IMA_MASK},
> + {.action = MEASURE,.func = PATH_CHECK,.mask = MAY_READ,.uid = 0,
> + .flags = IMA_FUNC | IMA_MASK | IMA_UID}
> +};
> +
> +static LIST_HEAD(measure_default_rules);
> +static struct list_head *ima_measure;
> +
> +/**
> + * ima_match_rules - determine whether an inode matches the measure rule.
> + * @rule: a pointer to a rule
> + * @inode: a pointer to an inode
> + * @func: LIM hook identifier
> + * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
> + *
> + * Returns true on rule match, false on failure.
> + */
> +static bool ima_match_rules(struct ima_measure_rule_entry *rule,
> + struct inode *inode, enum ima_hooks func, int mask)
> +{
> + struct task_struct *tsk = current;
> +
> + if ((rule->flags & IMA_FUNC) && rule->func != func)
> + return false;
> + if ((rule->flags & IMA_MASK) && rule->mask != mask)
> + return false;
> + if ((rule->flags & IMA_FSMAGIC)
> + && rule->fsmagic != inode->i_sb->s_magic)
> + return false;
> + if ((rule->flags & IMA_UID) && rule->uid != tsk->cred->uid)
> + return false;
> + return true;
> +}
> +
> +/**
> + * ima_match_policy - decision based on LSM and other conditions
> + * @inode: pointer to an inode for which the policy decision is being made
> + * @func: IMA hook identifier
> + * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
> + *
> + * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
> + * conditions.
> + *
> + * (There is no need for locking when walking the policy list,
> + * as elements in the list are never deleted, nor does the list
> + * change.)
> + */
> +int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask)
> +{
> + struct ima_measure_rule_entry *entry;
> +
> + list_for_each_entry(entry, ima_measure, list) {
The list never changes, but once per boot the value of ima_measure
itself can change (at least after a later patch). Does that matter?
Could you end up with a corrupt value here?
> + bool rc;
> +
> + rc = ima_match_rules(entry, inode, func, mask);
> + if (rc)
> + return entry->action;
> + }
> + return 0;
> +}
> +
> +/**
> + * ima_init_policy - initialize the default measure rules.
> + *
> + * (Could use the default_rules directly, but in policy patch
> + * ima_measure points to either the measure_default_rules or the
> + * the new measure_policy_rules.)
> + */
> +void ima_init_policy(void)
> +{
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(default_rules); i++)
> + list_add_tail(&default_rules[i].list, &measure_default_rules);
> + ima_measure = &measure_default_rules;
> +}
> diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
> new file mode 100644
> index 0000000..7cb518f
> --- /dev/null
> +++ b/security/integrity/ima/ima_queue.c
> @@ -0,0 +1,138 @@
> +/*
> + * Copyright (C) 2005,2006,2007,2008 IBM Corporation
> + *
> + * Authors:
> + * Serge Hallyn <serue@...ibm.com>
> + * Reiner Sailer <sailer@...son.ibm.com>
> + * Mimi Zohar <zohar@...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.
> + *
> + * File: ima_queue.c
> + * Implements queues that store template measurements and
> + * maintains aggregate over the stored measurements
> + * in the pre-configured TPM PCR (if available).
> + * The measurement list is append-only. No entry is
> + * ever removed or changed during the boot-cycle.
> + */
> +#include <linux/module.h>
> +#include <linux/rculist.h>
> +#include "ima.h"
> +
> +LIST_HEAD(ima_measurements); /* list of all measurements */
> +
> +/* key: inode (before secure-hashing a file) */
> +struct ima_h_table ima_htable = {
> + .len = ATOMIC_LONG_INIT(0),
> + .violations = ATOMIC_LONG_INIT(0),
> + .queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT
> +};
> +
> +/* mutex protects atomicity of extending measurement list
> + * and extending the TPM PCR aggregate. Since tpm_extend can take
> + * long (and the tpm driver uses a mutex), we can't use the spinlock.
> + */
> +static DEFINE_MUTEX(ima_extend_list_mutex);
> +
> +/* lookup up the digest value in the hash table, and return the entry */
> +static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value)
> +{
> + struct ima_queue_entry *qe, *ret = NULL;
> + unsigned int key;
> + struct hlist_node *pos;
> +
> + key = ima_hash_key(digest_value);
> + rcu_read_lock();
> + hlist_for_each_entry_rcu(qe, pos, &ima_htable.queue[key], hnext) {
> + if (memcmp(qe->entry->digest, digest_value, 20) == 0) {
> + ret = qe;
> + break;
> + }
> + }
> + rcu_read_unlock();
> + return ret;
> +}
> +
> +/* ima_add_template_entry helper function:
> + * - Add template entry to measurement list and hash table.
> + *
> + * (Called with ima_extend_list_mutex held.)
> + */
> +static int ima_add_digest_entry(struct ima_template_entry *entry)
> +{
> + struct ima_queue_entry *qe;
> + unsigned int key;
> +
> + qe = kmalloc(sizeof(*qe), GFP_KERNEL);
> + if (qe == NULL) {
> + pr_err("OUT OF MEMORY ERROR creating queue entry.\n");
> + return -ENOMEM;
> + }
> + qe->entry = entry;
> +
> + INIT_LIST_HEAD(&qe->later);
> + list_add_tail_rcu(&qe->later, &ima_measurements);
> +
> + atomic_long_inc(&ima_htable.len);
> + key = ima_hash_key(entry->digest);
> + hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]);
> + return 0;
> +}
> +
> +static int ima_pcr_extend(const u8 *hash)
> +{
> + int result = 0;
> +
> + if (!ima_used_chip)
> + return result;
> +
> + result = tpm_pcr_extend(TPM_ANY_NUM, CONFIG_IMA_MEASURE_PCR_IDX, hash);
> + if (result != 0)
> + pr_err("Error Communicating to TPM chip\n");
> + return result;
> +}
> +
> +/* Add template entry to the measurement list and hash table,
> + * and extend the pcr.
> + */
> +int ima_add_template_entry(struct ima_template_entry *entry, int violation,
> + const char *op, struct inode *inode)
> +{
> + u8 digest[IMA_DIGEST_SIZE];
> + const char *audit_cause = "hash_added";
> + int audit_info = 1;
> + int result = 0;
> +
> + mutex_lock(&ima_extend_list_mutex);
> + if (!violation) {
> + memcpy(digest, entry->digest, sizeof digest);
> + if (ima_lookup_digest_entry(digest)) {
> + audit_cause = "hash_exists";
> + goto out;
Ok so not that I'm saying this would be easy, but an attacker
compromising say ftpd doesn't need to come up with a compromised
ftpd where sha1sum(evilftpd)==sha1sum(origftpd) - he just needs to
come up with one wher sha1sum(evilftpd)==sha1sum(X) where X is
any pristine program already loaded. Right?
Is checking that strcmp(entry->file_name, newfilename)==0 warranted
here, or am I being silly?
> + }
> + }
> +
> + result = ima_add_digest_entry(entry);
> + if (result < 0) {
> + audit_cause = "ENOMEM";
> + audit_info = 0;
> + goto out;
> + }
> +
> + if (violation) /* invalidate pcr */
> + memset(digest, 0xff, sizeof digest);
> +
> + result = ima_pcr_extend(digest);
> + if (result != 0) {
> + audit_cause = "TPM error";
> + audit_info = 0;
> + }
> +out:
> + mutex_unlock(&ima_extend_list_mutex);
> + integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, entry->template_name,
> + op, audit_cause, result, audit_info);
> + return result;
> +}
> --
> 1.5.6.6
>
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