1 files changed, 565 insertions, 0 deletions

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
new file mode 100644
index 000000000..2d31921fb
--- /dev/null
+++ b/security/integrity/ima/ima_main.c
@@ -0,0 +1,565 @@
+/*
+ * 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.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#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 <linux/fs.h>
+
+#include "ima.h"
+
+#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;
+	}
+
+	i = match_string(hash_algo_name, HASH_ALGO__LAST, str);
+	if (i < 0)
+		return 1;
+
+	ima_hash_algo = i;
+out:
+	hash_setup_done = 1;
+	return 1;
+}
+__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");
+}
+
+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);
+}
+
+/**
+ * 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);
+}
+
+static int process_measurement(struct file *file, const struct cred *cred,
+			       u32 secid, char *buf, loff_t size, int mask,
+			       enum ima_hooks func)
+{
+	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, cred, secid, 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);
+
+	/*
+	 * Re-evaulate the file if either the xattr has changed or the
+	 * kernel has no way of detecting file change on the filesystem.
+	 * (Limited to privileged mounted filesystems.)
+	 */
+	if (test_and_clear_bit(IMA_CHANGE_XATTR, &iint->atomic_flags) ||
+	    ((inode->i_sb->s_iflags & SB_I_IMA_UNVERIFIABLE_SIGNATURE) &&
+	     !(inode->i_sb->s_iflags & SB_I_UNTRUSTED_MOUNTER) &&
+	     !(action & IMA_FAIL_UNVERIFIABLE_SIGS))) {
+		iint->flags &= ~IMA_DONE_MASK;
+		iint->measured_pcrs = 0;
+	}
+
+	/* 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);
+		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;
+}
+
+/**
+ * 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)
+{
+	u32 secid;
+
+	if (file && (prot & PROT_EXEC)) {
+		security_task_getsecid(current, &secid);
+		return process_measurement(file, current_cred(), secid, NULL,
+					   0, MAY_EXEC, MMAP_CHECK);
+	}
+
+	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.
+ *
+ * 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)
+{
+	int ret;
+	u32 secid;
+
+	security_task_getsecid(current, &secid);
+	ret = process_measurement(bprm->file, current_cred(), secid, NULL, 0,
+				  MAY_EXEC, BPRM_CHECK);
+	if (ret)
+		return ret;
+
+	security_cred_getsecid(bprm->cred, &secid);
+	return process_measurement(bprm->file, bprm->cred, secid, NULL, 0,
+				   MAY_EXEC, CREDS_CHECK);
+}
+
+/**
+ * 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)
+{
+	u32 secid;
+
+	security_task_getsecid(current, &secid);
+	return process_measurement(file, current_cred(), secid, NULL, 0,
+				   mask & (MAY_READ | MAY_WRITE | MAY_EXEC |
+					   MAY_APPEND), FILE_CHECK);
+}
+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;
+}
+
+/**
+ * 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)
+{
+	/*
+	 * READING_FIRMWARE_PREALLOC_BUFFER
+	 *
+	 * Do devices using pre-allocated memory run the risk of the
+	 * firmware being accessible to the device prior to the completion
+	 * of IMA's signature verification any more than when using two
+	 * buffers?
+	 */
+	return 0;
+}
+
+static int read_idmap[READING_MAX_ID] = {
+	[READING_FIRMWARE] = FIRMWARE_CHECK,
+	[READING_FIRMWARE_PREALLOC_BUFFER] = 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;
+	u32 secid;
+
+	if (!file && read_id == READING_FIRMWARE) {
+		if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
+		    (ima_appraise & IMA_APPRAISE_ENFORCE)) {
+			pr_err("Prevent firmware loading_store.\n");
+			return -EACCES;	/* INTEGRITY_UNKNOWN */
+		}
+		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;
+	security_task_getsecid(current, &secid);
+	return process_measurement(file, current_cred(), secid, buf, size,
+				   MAY_READ, func);
+}
+
+/**
+ * ima_load_data - appraise decision based on policy
+ * @id: kernel load data caller identifier
+ *
+ * Callers of this LSM hook can not measure, appraise, or audit the
+ * data provided by userspace.  Enforce policy rules requring a file
+ * signature (eg. kexec'ed kernel image).
+ *
+ * For permission return 0, otherwise return -EACCES.
+ */
+int ima_load_data(enum kernel_load_data_id id)
+{
+	bool sig_enforce;
+
+	if ((ima_appraise & IMA_APPRAISE_ENFORCE) != IMA_APPRAISE_ENFORCE)
+		return 0;
+
+	switch (id) {
+	case LOADING_KEXEC_IMAGE:
+		if (ima_appraise & IMA_APPRAISE_KEXEC) {
+			pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n");
+			return -EACCES;	/* INTEGRITY_UNKNOWN */
+		}
+		break;
+	case LOADING_FIRMWARE:
+		if (ima_appraise & IMA_APPRAISE_FIRMWARE) {
+			pr_err("Prevent firmware sysfs fallback loading.\n");
+			return -EACCES;	/* INTEGRITY_UNKNOWN */
+		}
+		break;
+	case LOADING_MODULE:
+		sig_enforce = is_module_sig_enforced();
+
+		if (!sig_enforce && (ima_appraise & IMA_APPRAISE_MODULES)) {
+			pr_err("impossible to appraise a module without a file descriptor. sig_enforce kernel parameter might help\n");
+			return -EACCES;	/* INTEGRITY_UNKNOWN */
+		}
+	default:
+		break;
+	}
+	return 0;
+}
+
+static int __init init_ima(void)
+{
+	int error;
+
+	ima_init_template_list();
+	hash_setup(CONFIG_IMA_DEFAULT_HASH);
+	error = ima_init();
+
+	if (error && strcmp(hash_algo_name[ima_hash_algo],
+			    CONFIG_IMA_DEFAULT_HASH) != 0) {
+		pr_info("Allocating %s failed, going to use default hash algorithm %s\n",
+			hash_algo_name[ima_hash_algo], CONFIG_IMA_DEFAULT_HASH);
+		hash_setup_done = 0;
+		hash_setup(CONFIG_IMA_DEFAULT_HASH);
+		error = ima_init();
+	}
+
+	if (!error)
+		ima_update_policy_flag();
+
+	return error;
+}
+
+late_initcall(init_ima);	/* Start IMA after the TPM is available */
+
+MODULE_DESCRIPTION("Integrity Measurement Architecture");
+MODULE_LICENSE("GPL");