Release 4.16 security/integrity/ima/ima_main.c

/*
 * 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_file_check.
 */
#include <linux/module.h>
#include <linux/file.h>
#include <linux/binfmts.h>
#include <linux/mount.h>
#include <linux/mman.h>
#include <linux/slab.h>
#include <linux/xattr.h>
#include <linux/ima.h>
#include <linux/iversion.h>

#include "ima.h"


int ima_initialized;

#ifdef CONFIG_IMA_APPRAISE

int ima_appraise = IMA_APPRAISE_ENFORCE;
#else

int ima_appraise;
#endif


int ima_hash_algo = HASH_ALGO_SHA1;

static int hash_setup_done;



static int __init hash_setup(char *str)
{
	struct ima_template_desc *template_desc = ima_template_desc_current();
	int i;

	if (hash_setup_done)
		return 1;

	if (strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) == 0) {
		if (strncmp(str, "sha1", 4) == 0)
			ima_hash_algo = HASH_ALGO_SHA1;
		else if (strncmp(str, "md5", 3) == 0)
			ima_hash_algo = HASH_ALGO_MD5;
		else
			return 1;
		goto out;
	}

	for (i = 0; i < HASH_ALGO__LAST; i++) {
		if (strcmp(str, hash_algo_name[i]) == 0) {
			ima_hash_algo = i;
			break;
		}
	}
	if (i == HASH_ALGO__LAST)
		return 1;
out:
	hash_setup_done = 1;
	return 1;
}
Contributors
Person
Tokens
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Commits
CommitProp
Mimi Zohar
125
89.29%
2
50.00%
Boshi Wang
13
9.29%
1
25.00%
Dmitry Kasatkin
2
1.43%
1
25.00%
Total
140
100.00%
4
100.00%

__setup("ima_hash=", hash_setup);

/*
 * ima_rdwr_violation_check
 *
 * 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.
 *
 */


static void ima_rdwr_violation_check(struct file *file,
				     struct integrity_iint_cache *iint,
				     int must_measure,
				     char **pathbuf,
				     const char **pathname,
				     char *filename)
{
	struct inode *inode = file_inode(file);
	fmode_t mode = file->f_mode;
	bool send_tomtou = false, send_writers = false;

	if (mode & FMODE_WRITE) {
		if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) {
			if (!iint)
				iint = integrity_iint_find(inode);
			/* IMA_MEASURE is set from reader side */
			if (iint && test_bit(IMA_MUST_MEASURE,
						&iint->atomic_flags))
				send_tomtou = true;
		}
	} else {
		if (must_measure)
			set_bit(IMA_MUST_MEASURE, &iint->atomic_flags);
		if ((atomic_read(&inode->i_writecount) > 0) && must_measure)
			send_writers = true;
	}

	if (!send_tomtou && !send_writers)
		return;

	*pathname = ima_d_path(&file->f_path, pathbuf, filename);

	if (send_tomtou)
		ima_add_violation(file, *pathname, iint,
				  "invalid_pcr", "ToMToU");
	if (send_writers)
		ima_add_violation(file, *pathname, iint,
				  "invalid_pcr", "open_writers");
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Eric Paris
77
36.15%
3
15.79%
Mimi Zohar
49
23.00%
6
31.58%
Dmitry Kasatkin
46
21.60%
4
21.05%
Roberto Sassu
37
17.37%
5
26.32%
David Howells
4
1.88%
1
5.26%
Total
213
100.00%
19
100.00%



static void ima_check_last_writer(struct integrity_iint_cache *iint,
				  struct inode *inode, struct file *file)
{
	fmode_t mode = file->f_mode;
	bool update;

	if (!(mode & FMODE_WRITE))
		return;

	mutex_lock(&iint->mutex);
	if (atomic_read(&inode->i_writecount) == 1) {
		update = test_and_clear_bit(IMA_UPDATE_XATTR,
					    &iint->atomic_flags);
		if (!IS_I_VERSION(inode) ||
		    !inode_eq_iversion(inode, iint->version) ||
		    (iint->flags & IMA_NEW_FILE)) {
			iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE);
			iint->measured_pcrs = 0;
			if (update)
				ima_update_xattr(iint, file);
		}
	}
	mutex_unlock(&iint->mutex);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Dmitry Kasatkin
44
31.65%
3
20.00%
Mimi Zohar
39
28.06%
4
26.67%
Eric Paris
37
26.62%
3
20.00%
Eric Richter
6
4.32%
1
6.67%
Sascha Hauer
6
4.32%
1
6.67%
Jeff Layton
4
2.88%
1
6.67%
Goffredo Baroncelli
2
1.44%
1
6.67%
Al Viro
1
0.72%
1
6.67%
Total
139
100.00%
15
100.00%

/**
 * ima_file_free - called on __fput()
 * @file: pointer to file structure being freed
 *
 * Flag files that changed, based on i_version
 */


void ima_file_free(struct file *file)
{
	struct inode *inode = file_inode(file);
	struct integrity_iint_cache *iint;

	if (!ima_policy_flag || !S_ISREG(inode->i_mode))
		return;

	iint = integrity_iint_find(inode);
	if (!iint)
		return;

	ima_check_last_writer(iint, inode, file);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Mimi Zohar
54
88.52%
4
57.14%
Al Viro
3
4.92%
1
14.29%
Eric Paris
3
4.92%
1
14.29%
Dmitry Kasatkin
1
1.64%
1
14.29%
Total
61
100.00%
7
100.00%



static int process_measurement(struct file *file, char *buf, loff_t size,
			       int mask, enum ima_hooks func, int opened)
{
	struct inode *inode = file_inode(file);
	struct integrity_iint_cache *iint = NULL;
	struct ima_template_desc *template_desc;
	char *pathbuf = NULL;
	char filename[NAME_MAX];
	const char *pathname = NULL;
	int rc = 0, action, must_appraise = 0;
	int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
	struct evm_ima_xattr_data *xattr_value = NULL;
	int xattr_len = 0;
	bool violation_check;
	enum hash_algo hash_algo;

	if (!ima_policy_flag || !S_ISREG(inode->i_mode))
		return 0;

	/* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action
         * bitmask based on the appraise/audit/measurement policy.
         * Included is the appraise submask.
         */
	action = ima_get_action(inode, mask, func, &pcr);
	violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) &&
			   (ima_policy_flag & IMA_MEASURE));
	if (!action && !violation_check)
		return 0;

	must_appraise = action & IMA_APPRAISE;

	/*  Is the appraise rule hook specific?  */
	if (action & IMA_FILE_APPRAISE)
		func = FILE_CHECK;

	inode_lock(inode);

	if (action) {
		iint = integrity_inode_get(inode);
		if (!iint)
			rc = -ENOMEM;
	}

	if (!rc && violation_check)
		ima_rdwr_violation_check(file, iint, action & IMA_MEASURE,
					 &pathbuf, &pathname, filename);

	inode_unlock(inode);

	if (rc)
		goto out;
	if (!action)
		goto out;

	mutex_lock(&iint->mutex);

	if (test_and_clear_bit(IMA_CHANGE_ATTR, &iint->atomic_flags))
		/* reset appraisal flags if ima_inode_post_setattr was called */
		iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
				 IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
				 IMA_ACTION_FLAGS);

	if (test_and_clear_bit(IMA_CHANGE_XATTR, &iint->atomic_flags))
		/* reset all flags if ima_inode_setxattr was called */
		iint->flags &= ~IMA_DONE_MASK;

	/* Determine if already appraised/measured based on bitmask
         * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
         *  IMA_AUDIT, IMA_AUDITED)
         */
	iint->flags |= action;
	action &= IMA_DO_MASK;
	action &= ~((iint->flags & (IMA_DONE_MASK ^ IMA_MEASURED)) >> 1);

	/* If target pcr is already measured, unset IMA_MEASURE action */
	if ((action & IMA_MEASURE) && (iint->measured_pcrs & (0x1 << pcr)))
		action ^= IMA_MEASURE;

	/* HASH sets the digital signature and update flags, nothing else */
	if ((action & IMA_HASH) &&
	    !(test_bit(IMA_DIGSIG, &iint->atomic_flags))) {
		xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
		if ((xattr_value && xattr_len > 2) &&
		    (xattr_value->type == EVM_IMA_XATTR_DIGSIG))
			set_bit(IMA_DIGSIG, &iint->atomic_flags);
		iint->flags |= IMA_HASHED;
		action ^= IMA_HASH;
		set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
	}

	/* Nothing to do, just return existing appraised status */
	if (!action) {
		if (must_appraise)
			rc = ima_get_cache_status(iint, func);
		goto out_locked;
	}

	template_desc = ima_template_desc_current();
	if ((action & IMA_APPRAISE_SUBMASK) ||
		    strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0)
		/* read 'security.ima' */
		xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);

	hash_algo = ima_get_hash_algo(xattr_value, xattr_len);

	rc = ima_collect_measurement(iint, file, buf, size, hash_algo);
	if (rc != 0 && rc != -EBADF && rc != -EINVAL)
		goto out_locked;

	if (!pathbuf)	/* ima_rdwr_violation possibly pre-fetched */
		pathname = ima_d_path(&file->f_path, &pathbuf, filename);

	if (action & IMA_MEASURE)
		ima_store_measurement(iint, file, pathname,
				      xattr_value, xattr_len, pcr);
	if (rc == 0 && (action & IMA_APPRAISE_SUBMASK)) {
		inode_lock(inode);
		rc = ima_appraise_measurement(func, iint, file, pathname,
					      xattr_value, xattr_len, opened);
		inode_unlock(inode);
	}
	if (action & IMA_AUDIT)
		ima_audit_measurement(iint, pathname);

	if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO))
		rc = 0;
out_locked:
	if ((mask & MAY_WRITE) && test_bit(IMA_DIGSIG, &iint->atomic_flags) &&
	     !(iint->flags & IMA_NEW_FILE))
		rc = -EACCES;
	mutex_unlock(&iint->mutex);
	kfree(xattr_value);
out:
	if (pathbuf)
		__putname(pathbuf);
	if (must_appraise) {
		if (rc && (ima_appraise & IMA_APPRAISE_ENFORCE))
			return -EACCES;
		if (file->f_mode & FMODE_WRITE)
			set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
	}
	return 0;
}

Contributors
Person
Tokens
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Commits
CommitProp
Mimi Zohar
348
44.67%
16
36.36%
Dmitry Kasatkin
249
31.96%
15
34.09%
Roberto Sassu
101
12.97%
5
11.36%
Eric Richter
39
5.01%
3
6.82%
Eric Paris
22
2.82%
1
2.27%
Peter Moody
13
1.67%
1
2.27%
Al Viro
4
0.51%
2
4.55%
Miklos Szeredi
3
0.39%
1
2.27%
Total
779
100.00%
44
100.00%

/**
 * 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.
 *
 * On success return 0.  On integrity appraisal error, assuming the file
 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
 */


int ima_file_mmap(struct file *file, unsigned long prot)
{
	if (file && (prot & PROT_EXEC))
		return process_measurement(file, NULL, 0, MAY_EXEC,
					   MMAP_CHECK, 0);
	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Mimi Zohar
36
83.72%
3
60.00%
Dmitry Kasatkin
7
16.28%
2
40.00%
Total
43
100.00%
5
100.00%

/**
 * 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.
 *
 * On success return 0.  On integrity appraisal error, assuming the file
 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
 */


int ima_bprm_check(struct linux_binprm *bprm)
{
	return process_measurement(bprm->file, NULL, 0, MAY_EXEC,
				   BPRM_CHECK, 0);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Mimi Zohar
25
89.29%
2
50.00%
Dmitry Kasatkin
3
10.71%
2
50.00%
Total
28
100.00%
4
100.00%

/**
 * ima_path_check - based on policy, collect/store measurement.
 * @file: pointer to the file to be measured
 * @mask: contains MAY_READ, MAY_WRITE, MAY_EXEC or MAY_APPEND
 *
 * Measure files based on the ima_must_measure() policy decision.
 *
 * On success return 0.  On integrity appraisal error, assuming the file
 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
 */


int ima_file_check(struct file *file, int mask, int opened)
{
	return process_measurement(file, NULL, 0,
				   mask & (MAY_READ | MAY_WRITE | MAY_EXEC |
					   MAY_APPEND), FILE_CHECK, opened);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Mimi Zohar
34
80.95%
4
57.14%
Dmitry Kasatkin
6
14.29%
2
28.57%
Lans Zhang
2
4.76%
1
14.29%
Total
42
100.00%
7
100.00%

EXPORT_SYMBOL_GPL(ima_file_check);

/**
 * ima_post_path_mknod - mark as a new inode
 * @dentry: newly created dentry
 *
 * Mark files created via the mknodat syscall as new, so that the
 * file data can be written later.
 */


void ima_post_path_mknod(struct dentry *dentry)
{
	struct integrity_iint_cache *iint;
	struct inode *inode = dentry->d_inode;
	int must_appraise;

	must_appraise = ima_must_appraise(inode, MAY_ACCESS, FILE_CHECK);
	if (!must_appraise)
		return;

	iint = integrity_inode_get(inode);
	if (iint)
		iint->flags |= IMA_NEW_FILE;
}

Contributors
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Tokens
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CommitProp
Mimi Zohar
61
100.00%
1
100.00%
Total
61
100.00%
1
100.00%

/**
 * ima_read_file - pre-measure/appraise hook decision based on policy
 * @file: pointer to the file to be measured/appraised/audit
 * @read_id: caller identifier
 *
 * Permit reading a file based on policy. The policy rules are written
 * in terms of the policy identifier.  Appraising the integrity of
 * a file requires a file descriptor.
 *
 * For permission return 0, otherwise return -EACCES.
 */


int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
{
	bool sig_enforce = is_module_sig_enforced();

	if (!file && read_id == READING_MODULE) {
		if (!sig_enforce && (ima_appraise & IMA_APPRAISE_MODULES) &&
		    (ima_appraise & IMA_APPRAISE_ENFORCE)) {
			pr_err("impossible to appraise a module without a file descriptor. sig_enforce kernel parameter might help\n");
			return -EACCES;	/* INTEGRITY_UNKNOWN */
		}
		return 0;	/* We rely on module signature checking */
	}
	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Mimi Zohar
44
65.67%
5
55.56%
Bruno E. O. Meneguele
9
13.43%
1
11.11%
Bruno E O Meneguele
7
10.45%
1
11.11%
Linus Torvalds
4
5.97%
1
11.11%
Dmitry Kasatkin
3
4.48%
1
11.11%
Total
67
100.00%
9
100.00%


static int read_idmap[READING_MAX_ID] = {
	[READING_FIRMWARE] = FIRMWARE_CHECK,
	[READING_MODULE] = MODULE_CHECK,
	[READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK,
	[READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK,
	[READING_POLICY] = POLICY_CHECK
};

/**
 * ima_post_read_file - in memory collect/appraise/audit measurement
 * @file: pointer to the file to be measured/appraised/audit
 * @buf: pointer to in memory file contents
 * @size: size of in memory file contents
 * @read_id: caller identifier
 *
 * Measure/appraise/audit in memory file based on policy.  Policy rules
 * are written in terms of a policy identifier.
 *
 * On success return 0.  On integrity appraisal error, assuming the file
 * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
 */


int ima_post_read_file(struct file *file, void *buf, loff_t size,
		       enum kernel_read_file_id read_id)
{
	enum ima_hooks func;

	if (!file && read_id == READING_FIRMWARE) {
		if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
		    (ima_appraise & IMA_APPRAISE_ENFORCE))
			return -EACCES;	/* INTEGRITY_UNKNOWN */
		return 0;
	}

	if (!file && read_id == READING_MODULE) /* MODULE_SIG_FORCE enabled */
		return 0;

	/* permit signed certs */
	if (!file && read_id == READING_X509_CERTIFICATE)
		return 0;

	if (!file || !buf || size == 0) { /* should never happen */
		if (ima_appraise & IMA_APPRAISE_ENFORCE)
			return -EACCES;
		return 0;
	}

	func = read_idmap[read_id] ?: FILE_CHECK;
	return process_measurement(file, buf, size, MAY_READ, func, 0);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Mimi Zohar
125
90.58%
5
83.33%
Christoph Hellwig
13
9.42%
1
16.67%
Total
138
100.00%
6
100.00%



static int __init init_ima(void)
{
	int error;

	ima_init_template_list();
	hash_setup(CONFIG_IMA_DEFAULT_HASH);
	error = ima_init();
	if (!error) {
		ima_initialized = 1;
		ima_update_policy_flag();
	}
	return error;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Mimi Zohar
32
76.19%
3
50.00%
Roberto Sassu
5
11.90%
1
16.67%
Dmitry Kasatkin
5
11.90%
2
33.33%
Total
42
100.00%
6
100.00%

late_initcall(init_ima);	/* Start IMA after the TPM is available */

MODULE_DESCRIPTION("Integrity Measurement Architecture");
MODULE_LICENSE("GPL");
Overall Contributors
Person
Tokens
Prop
Commits
CommitProp
Mimi Zohar
1089
57.74%
34
37.36%
Dmitry Kasatkin
372
19.72%
23
25.27%
Roberto Sassu
143
7.58%
7
7.69%
Eric Paris
139
7.37%
7
7.69%
Eric Richter
45
2.39%
3
3.30%
Christoph Hellwig
13
0.69%
1
1.10%
Peter Moody
13
0.69%
1
1.10%
Boshi Wang
13
0.69%
1
1.10%
Bruno E. O. Meneguele
9
0.48%
1
1.10%
Al Viro
8
0.42%
3
3.30%
Jeff Layton
7
0.37%
1
1.10%
Bruno E O Meneguele
7
0.37%
1
1.10%
Sascha Hauer
6
0.32%
1
1.10%
Linus Torvalds
4
0.21%
1
1.10%
David Howells
4
0.21%
1
1.10%
Lans Zhang
3
0.16%
1
1.10%
Tejun Heo
3
0.16%
1
1.10%
James Morris
3
0.16%
1
1.10%
Miklos Szeredi
3
0.16%
1
1.10%
Goffredo Baroncelli
2
0.11%
1
1.10%
Total
1886
100.00%
91
100.00%
Directory: security/integrity/ima

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