| /* |
| * 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 <crypto/hash_info.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; |
| goto out; |
| } |
| |
| for (i = 0; i < HASH_ALGO__LAST; i++) { |
| if (strcmp(str, hash_algo_name[i]) == 0) { |
| ima_hash_algo = i; |
| break; |
| } |
| } |
| 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) |
| { |
| 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 && (iint->flags & IMA_MEASURE)) |
| send_tomtou = true; |
| } |
| } else { |
| 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); |
| |
| 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; |
| |
| if (!(mode & FMODE_WRITE)) |
| return; |
| |
| inode_lock(inode); |
| if (atomic_read(&inode->i_writecount) == 1) { |
| if ((iint->version != inode->i_version) || |
| (iint->flags & IMA_NEW_FILE)) { |
| iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE); |
| if (iint->flags & IMA_APPRAISE) |
| ima_update_xattr(iint, file); |
| } |
| } |
| inode_unlock(inode); |
| } |
| |
| /** |
| * 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, int mask, int function, |
| int opened) |
| { |
| struct inode *inode = file_inode(file); |
| struct integrity_iint_cache *iint = NULL; |
| struct ima_template_desc *template_desc; |
| char *pathbuf = NULL; |
| const char *pathname = NULL; |
| int rc = -ENOMEM, action, must_appraise; |
| struct evm_ima_xattr_data *xattr_value = NULL, **xattr_ptr = NULL; |
| int xattr_len = 0; |
| bool violation_check; |
| |
| 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, function); |
| violation_check = ((function == FILE_CHECK || function == 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) |
| function = FILE_CHECK; |
| |
| inode_lock(inode); |
| |
| if (action) { |
| iint = integrity_inode_get(inode); |
| if (!iint) |
| goto out; |
| } |
| |
| if (violation_check) { |
| ima_rdwr_violation_check(file, iint, action & IMA_MEASURE, |
| &pathbuf, &pathname); |
| if (!action) { |
| rc = 0; |
| goto out_free; |
| } |
| } |
| |
| /* 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) >> 1); |
| |
| /* Nothing to do, just return existing appraised status */ |
| if (!action) { |
| if (must_appraise) |
| rc = ima_get_cache_status(iint, function); |
| goto out_digsig; |
| } |
| |
| template_desc = ima_template_desc_current(); |
| if ((action & IMA_APPRAISE_SUBMASK) || |
| strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0) |
| xattr_ptr = &xattr_value; |
| |
| rc = ima_collect_measurement(iint, file, xattr_ptr, &xattr_len); |
| if (rc != 0) { |
| if (file->f_flags & O_DIRECT) |
| rc = (iint->flags & IMA_PERMIT_DIRECTIO) ? 0 : -EACCES; |
| goto out_digsig; |
| } |
| |
| if (!pathname) /* ima_rdwr_violation possibly pre-fetched */ |
| pathname = ima_d_path(&file->f_path, &pathbuf); |
| |
| if (action & IMA_MEASURE) |
| ima_store_measurement(iint, file, pathname, |
| xattr_value, xattr_len); |
| if (action & IMA_APPRAISE_SUBMASK) |
| rc = ima_appraise_measurement(function, iint, file, pathname, |
| xattr_value, xattr_len, opened); |
| if (action & IMA_AUDIT) |
| ima_audit_measurement(iint, pathname); |
| |
| out_digsig: |
| if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG)) |
| rc = -EACCES; |
| kfree(xattr_value); |
| out_free: |
| if (pathbuf) |
| __putname(pathbuf); |
| out: |
| inode_unlock(inode); |
| if ((rc && must_appraise) && (ima_appraise & IMA_APPRAISE_ENFORCE)) |
| return -EACCES; |
| 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) |
| { |
| if (file && (prot & PROT_EXEC)) |
| return process_measurement(file, MAY_EXEC, MMAP_CHECK, 0); |
| 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) |
| { |
| return process_measurement(bprm->file, MAY_EXEC, BPRM_CHECK, 0); |
| } |
| |
| /** |
| * ima_path_check - based on policy, collect/store measurement. |
| * @file: pointer to the file to be measured |
| * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE |
| * |
| * 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, |
| mask & (MAY_READ | MAY_WRITE | MAY_EXEC), |
| FILE_CHECK, opened); |
| } |
| EXPORT_SYMBOL_GPL(ima_file_check); |
| |
| /** |
| * ima_module_check - based on policy, collect/store/appraise measurement. |
| * @file: pointer to the file to be measured/appraised |
| * |
| * Measure/appraise kernel modules based on policy. |
| * |
| * 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_module_check(struct file *file) |
| { |
| if (!file) { |
| #ifndef CONFIG_MODULE_SIG_FORCE |
| if ((ima_appraise & IMA_APPRAISE_MODULES) && |
| (ima_appraise & IMA_APPRAISE_ENFORCE)) |
| return -EACCES; /* INTEGRITY_UNKNOWN */ |
| #endif |
| return 0; /* We rely on module signature checking */ |
| } |
| return process_measurement(file, MAY_EXEC, MODULE_CHECK, 0); |
| } |
| |
| int ima_fw_from_file(struct file *file, char *buf, size_t size) |
| { |
| if (!file) { |
| if ((ima_appraise & IMA_APPRAISE_FIRMWARE) && |
| (ima_appraise & IMA_APPRAISE_ENFORCE)) |
| return -EACCES; /* INTEGRITY_UNKNOWN */ |
| return 0; |
| } |
| return process_measurement(file, MAY_EXEC, FIRMWARE_CHECK, 0); |
| } |
| |
| static int __init init_ima(void) |
| { |
| int error; |
| |
| hash_setup(CONFIG_IMA_DEFAULT_HASH); |
| error = ima_init(); |
| if (!error) { |
| ima_initialized = 1; |
| 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"); |