mirror of https://gitee.com/openkylin/linux.git
307 lines
8.1 KiB
C
307 lines
8.1 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 <linux/xattr.h>
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#include <linux/ima.h>
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#include "ima.h"
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int ima_initialized;
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#ifdef CONFIG_IMA_APPRAISE
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int ima_appraise = IMA_APPRAISE_ENFORCE;
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#else
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int ima_appraise;
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#endif
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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 = file_inode(file);
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fmode_t mode = file->f_mode;
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int must_measure;
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bool send_tomtou = false, send_writers = false;
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char *pathbuf = NULL;
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const char *pathname;
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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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must_measure = ima_must_measure(inode, MAY_READ, FILE_CHECK);
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if (!must_measure)
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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 && !send_writers)
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return;
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pathname = ima_d_path(&file->f_path, &pathbuf);
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if (!pathname || strlen(pathname) > IMA_EVENT_NAME_LEN_MAX)
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pathname = dentry->d_name.name;
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if (send_tomtou)
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ima_add_violation(inode, pathname,
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"invalid_pcr", "ToMToU");
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if (send_writers)
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ima_add_violation(inode, pathname,
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"invalid_pcr", "open_writers");
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kfree(pathbuf);
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}
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static void ima_check_last_writer(struct integrity_iint_cache *iint,
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struct inode *inode, struct file *file)
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{
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fmode_t mode = file->f_mode;
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if (!(mode & FMODE_WRITE))
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return;
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mutex_lock(&inode->i_mutex);
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if (atomic_read(&inode->i_writecount) == 1 &&
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iint->version != inode->i_version) {
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iint->flags &= ~IMA_DONE_MASK;
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if (iint->flags & IMA_APPRAISE)
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ima_update_xattr(iint, file);
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}
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mutex_unlock(&inode->i_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_inode(file);
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struct integrity_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 = integrity_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 char *filename,
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int mask, int function)
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{
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struct inode *inode = file_inode(file);
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struct integrity_iint_cache *iint;
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char *pathbuf = NULL;
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const char *pathname = NULL;
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int rc = -ENOMEM, action, must_appraise, _func;
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if (!ima_initialized || !S_ISREG(inode->i_mode))
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return 0;
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/* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action
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* bitmask based on the appraise/audit/measurement policy.
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* Included is the appraise submask.
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*/
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action = ima_get_action(inode, mask, function);
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if (!action)
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return 0;
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must_appraise = action & IMA_APPRAISE;
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/* Is the appraise rule hook specific? */
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_func = (action & IMA_FILE_APPRAISE) ? FILE_CHECK : function;
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mutex_lock(&inode->i_mutex);
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iint = integrity_inode_get(inode);
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if (!iint)
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goto out;
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/* Determine if already appraised/measured based on bitmask
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* (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
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* IMA_AUDIT, IMA_AUDITED)
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*/
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iint->flags |= action;
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action &= IMA_DO_MASK;
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action &= ~((iint->flags & IMA_DONE_MASK) >> 1);
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/* Nothing to do, just return existing appraised status */
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if (!action) {
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if (must_appraise)
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rc = ima_get_cache_status(iint, _func);
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goto out_digsig;
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}
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rc = ima_collect_measurement(iint, file);
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if (rc != 0)
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goto out_digsig;
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pathname = !filename ? ima_d_path(&file->f_path, &pathbuf) : filename;
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if (!pathname)
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pathname = (const char *)file->f_dentry->d_name.name;
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if (action & IMA_MEASURE)
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ima_store_measurement(iint, file, pathname);
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if (action & IMA_APPRAISE_SUBMASK)
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rc = ima_appraise_measurement(_func, iint, file, pathname);
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if (action & IMA_AUDIT)
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ima_audit_measurement(iint, pathname);
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kfree(pathbuf);
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out_digsig:
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if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG))
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rc = -EACCES;
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out:
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mutex_unlock(&inode->i_mutex);
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if ((rc && must_appraise) && (ima_appraise & IMA_APPRAISE_ENFORCE))
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return -EACCES;
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return 0;
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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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* On success return 0. On integrity appraisal error, assuming the file
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* is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
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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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if (file && (prot & PROT_EXEC))
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return process_measurement(file, NULL, MAY_EXEC, MMAP_CHECK);
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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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* On success return 0. On integrity appraisal error, assuming the file
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* is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
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*/
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int ima_bprm_check(struct linux_binprm *bprm)
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{
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return process_measurement(bprm->file,
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(strcmp(bprm->filename, bprm->interp) == 0) ?
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bprm->filename : bprm->interp,
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MAY_EXEC, BPRM_CHECK);
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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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* On success return 0. On integrity appraisal error, assuming the file
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* is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
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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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ima_rdwr_violation_check(file);
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return process_measurement(file, NULL,
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mask & (MAY_READ | MAY_WRITE | MAY_EXEC),
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FILE_CHECK);
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}
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EXPORT_SYMBOL_GPL(ima_file_check);
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/**
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* ima_module_check - based on policy, collect/store/appraise measurement.
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* @file: pointer to the file to be measured/appraised
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*
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* Measure/appraise kernel modules based on policy.
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*
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* On success return 0. On integrity appraisal error, assuming the file
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* is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
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*/
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int ima_module_check(struct file *file)
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{
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if (!file) {
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#ifndef CONFIG_MODULE_SIG_FORCE
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if ((ima_appraise & IMA_APPRAISE_MODULES) &&
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(ima_appraise & IMA_APPRAISE_ENFORCE))
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return -EACCES; /* INTEGRITY_UNKNOWN */
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#endif
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return 0; /* We rely on module signature checking */
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}
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return process_measurement(file, NULL, MAY_EXEC, MODULE_CHECK);
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}
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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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if (!error)
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ima_initialized = 1;
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return error;
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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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