Messages in this thread | | | Date | Mon, 2 Feb 2009 17:02:11 -0600 | From | "Serge E. Hallyn" <> | Subject | Re: [PATCH 2/6] integrity: IMA as an integrity service provider |
| |
Quoting Mimi Zohar (zohar@linux.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@us.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@us.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@watson.ibm.com> > + * Mimi Zohar <zohar@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. > + * > + * 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@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. > + * > + * 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@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. > + * > + * 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@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. > + * > + * 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@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. > + * > + * 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@watson.ibm.com> > + * Leendert van Doorn <leendert@watson.ibm.com> > + * Mimi Zohar <zohar@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. > + * > + * 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@watson.ibm.com> > + * Serge Hallyn <serue@us.ibm.com> > + * Kylene Hall <kylene@us.ibm.com> > + * Mimi Zohar <zohar@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. > + * > + * 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@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. > + * > + * 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@us.ibm.com> > + * Reiner Sailer <sailer@watson.ibm.com> > + * Mimi Zohar <zohar@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. > + * > + * 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 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
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