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1adace9bb0
The original ima_must_measure() function based its results on cached iint information, which required an iint be allocated for all files. Currently, an iint is allocated only for files in policy. As a result, for those files in policy, ima_must_measure() is now called twice: once to determine if the inode is in the measurement policy and, the second time, to determine if it needs to be measured/re-measured. The second call to ima_must_measure() unnecessarily checks to see if the file is in policy. As we already know the file is in policy, this patch removes the second unnecessary call to ima_must_measure(), removes the vestige iint parameter, and just checks the iint directly to determine if the inode has been measured or needs to be measured/re-measured. Signed-off-by: Mimi Zohar <zohar@us.ibm.com> Acked-by: Eric Paris <eparis@redhat.com>
241 lines
5.7 KiB
C
241 lines
5.7 KiB
C
/*
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* Copyright (C) 2005,2006,2007,2008 IBM Corporation
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*
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* Authors:
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* Reiner Sailer <sailer@watson.ibm.com>
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* Serge Hallyn <serue@us.ibm.com>
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* Kylene Hall <kylene@us.ibm.com>
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* Mimi Zohar <zohar@us.ibm.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, version 2 of the
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* License.
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*
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* File: ima_main.c
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* implements the IMA hooks: ima_bprm_check, ima_file_mmap,
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* and ima_file_check.
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*/
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#include <linux/module.h>
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#include <linux/file.h>
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#include <linux/binfmts.h>
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#include <linux/mount.h>
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#include <linux/mman.h>
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#include <linux/slab.h>
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#include "ima.h"
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int ima_initialized;
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char *ima_hash = "sha1";
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static int __init hash_setup(char *str)
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{
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if (strncmp(str, "md5", 3) == 0)
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ima_hash = "md5";
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return 1;
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}
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__setup("ima_hash=", hash_setup);
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/*
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* ima_rdwr_violation_check
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*
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* Only invalidate the PCR for measured files:
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* - Opening a file for write when already open for read,
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* results in a time of measure, time of use (ToMToU) error.
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* - Opening a file for read when already open for write,
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* could result in a file measurement error.
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*
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*/
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static void ima_rdwr_violation_check(struct file *file)
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{
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struct dentry *dentry = file->f_path.dentry;
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struct inode *inode = dentry->d_inode;
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fmode_t mode = file->f_mode;
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int rc;
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bool send_tomtou = false, send_writers = false;
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if (!S_ISREG(inode->i_mode) || !ima_initialized)
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return;
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mutex_lock(&inode->i_mutex); /* file metadata: permissions, xattr */
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if (mode & FMODE_WRITE) {
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if (atomic_read(&inode->i_readcount) && IS_IMA(inode))
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send_tomtou = true;
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goto out;
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}
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rc = ima_must_measure(inode, MAY_READ, FILE_CHECK);
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if (rc < 0)
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goto out;
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if (atomic_read(&inode->i_writecount) > 0)
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send_writers = true;
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out:
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mutex_unlock(&inode->i_mutex);
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if (send_tomtou)
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ima_add_violation(inode, dentry->d_name.name, "invalid_pcr",
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"ToMToU");
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if (send_writers)
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ima_add_violation(inode, dentry->d_name.name, "invalid_pcr",
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"open_writers");
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}
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static void ima_check_last_writer(struct ima_iint_cache *iint,
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struct inode *inode,
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struct file *file)
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{
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mode_t mode = file->f_mode;
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mutex_lock(&iint->mutex);
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if (mode & FMODE_WRITE &&
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atomic_read(&inode->i_writecount) == 1 &&
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iint->version != inode->i_version)
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iint->flags &= ~IMA_MEASURED;
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mutex_unlock(&iint->mutex);
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}
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/**
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* ima_file_free - called on __fput()
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* @file: pointer to file structure being freed
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*
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* Flag files that changed, based on i_version
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*/
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void ima_file_free(struct file *file)
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{
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struct inode *inode = file->f_dentry->d_inode;
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struct ima_iint_cache *iint;
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if (!iint_initialized || !S_ISREG(inode->i_mode))
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return;
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iint = ima_iint_find(inode);
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if (!iint)
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return;
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ima_check_last_writer(iint, inode, file);
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}
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static int process_measurement(struct file *file, const unsigned char *filename,
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int mask, int function)
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{
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struct inode *inode = file->f_dentry->d_inode;
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struct ima_iint_cache *iint;
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int rc = 0;
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if (!ima_initialized || !S_ISREG(inode->i_mode))
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return 0;
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rc = ima_must_measure(inode, mask, function);
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if (rc != 0)
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return rc;
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retry:
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iint = ima_iint_find(inode);
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if (!iint) {
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rc = ima_inode_alloc(inode);
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if (!rc || rc == -EEXIST)
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goto retry;
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return rc;
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}
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mutex_lock(&iint->mutex);
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rc = iint->flags & IMA_MEASURED ? 1 : 0;
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if (rc != 0)
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goto out;
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rc = ima_collect_measurement(iint, file);
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if (!rc)
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ima_store_measurement(iint, file, filename);
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out:
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mutex_unlock(&iint->mutex);
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return rc;
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}
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/**
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* ima_file_mmap - based on policy, collect/store measurement.
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* @file: pointer to the file to be measured (May be NULL)
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* @prot: contains the protection that will be applied by the kernel.
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*
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* Measure files being mmapped executable based on the ima_must_measure()
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* policy decision.
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*
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* Return 0 on success, an error code on failure.
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* (Based on the results of appraise_measurement().)
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*/
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int ima_file_mmap(struct file *file, unsigned long prot)
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{
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int rc;
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if (!file)
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return 0;
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if (prot & PROT_EXEC)
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rc = process_measurement(file, file->f_dentry->d_name.name,
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MAY_EXEC, FILE_MMAP);
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return 0;
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}
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/**
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* ima_bprm_check - based on policy, collect/store measurement.
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* @bprm: contains the linux_binprm structure
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*
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* The OS protects against an executable file, already open for write,
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* from being executed in deny_write_access() and an executable file,
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* already open for execute, from being modified in get_write_access().
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* So we can be certain that what we verify and measure here is actually
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* what is being executed.
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*
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* Return 0 on success, an error code on failure.
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* (Based on the results of appraise_measurement().)
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*/
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int ima_bprm_check(struct linux_binprm *bprm)
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{
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int rc;
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rc = process_measurement(bprm->file, bprm->filename,
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MAY_EXEC, BPRM_CHECK);
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return 0;
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}
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/**
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* ima_path_check - based on policy, collect/store measurement.
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* @file: pointer to the file to be measured
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* @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
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*
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* Measure files based on the ima_must_measure() policy decision.
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*
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* Always return 0 and audit dentry_open failures.
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* (Return code will be based upon measurement appraisal.)
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*/
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int ima_file_check(struct file *file, int mask)
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{
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int rc;
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ima_rdwr_violation_check(file);
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rc = process_measurement(file, file->f_dentry->d_name.name,
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mask & (MAY_READ | MAY_WRITE | MAY_EXEC),
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FILE_CHECK);
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return 0;
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}
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EXPORT_SYMBOL_GPL(ima_file_check);
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static int __init init_ima(void)
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{
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int error;
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error = ima_init();
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ima_initialized = 1;
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return error;
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}
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static void __exit cleanup_ima(void)
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{
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ima_cleanup();
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}
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late_initcall(init_ima); /* Start IMA after the TPM is available */
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MODULE_DESCRIPTION("Integrity Measurement Architecture");
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MODULE_LICENSE("GPL");
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