text: /*
   * Integrity Measurement Architecture
   *
   * 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 (inode_is_open_for_write(inode) && 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_create_tmpfile - mark newly created tmpfile as new
   * @file : newly created tmpfile
   *
   * No measuring, appraising or auditing of newly created tmpfiles is needed.
   * Skip calling process_measurement(), but indicate which newly, created
   * tmpfiles are in policy.
   */
  void ima_post_create_tmpfile(struct inode *inode)
  {
  	struct integrity_iint_cache *iint;
  	int must_appraise;
  
  	must_appraise = ima_must_appraise(inode, MAY_ACCESS, FILE_CHECK);
  	if (!must_appraise)
  		return;
  
  	/* Nothing to do if we can't allocate memory */
  	iint = integrity_inode_get(inode);
  	if (!iint)
  		return;
  
  	/* needed for writing the security xattrs */
  	set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
  	iint->ima_file_status = INTEGRITY_PASS;
  }
  
  /**
   * 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;
  
  	/* Nothing to do if we can't allocate memory */
  	iint = integrity_inode_get(inode);
  	if (!iint)
  		return;
  
  	/* needed for re-opening empty files */
  	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 const 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 ima_enforce, sig_enforce;
  
  	ima_enforce =
  		(ima_appraise & IMA_APPRAISE_ENFORCE) == IMA_APPRAISE_ENFORCE;
  
  	switch (id) {
  	case LOADING_KEXEC_IMAGE:
  		if (IS_ENABLED(CONFIG_KEXEC_VERIFY_SIG)
  		    && arch_ima_get_secureboot()) {
  			pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n");
  			return -EACCES;
  		}
  
  		if (ima_enforce && (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_enforce && (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 (ima_enforce && (!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 */
  