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-----BEGIN PGP SIGNATURE----- iQJIBAABCAAyFiEEjSMCCC7+cjo3nszSa3kkZrA+cVoFAl/X/p4UHHpvaGFyQGxp bnV4LmlibS5jb20ACgkQa3kkZrA+cVq/0w//QatvPcNJ/lrfR28J3Jdf2dPWChEr OzeTuCT3/gPKvwtvT5QbaJVEJfSzeZb2SnOIRExOoIMET5kwCSWBAXLgU/eFy5jV 5fXOh8HjONNTEsP/o8ycHw43fQ+BxM0x6aayatGda2PREArF47YfKQ4drlB2znLG veHmwk+42Bj4TgP1C1dv1MQwSUlaC0iu4lYu7c3kM/LftUjvgDv0+dkhhOKfgJMG 3spUkSb9XfCl3qCqPy6wa1768bsvRwf7mTGRN/dfFtlfIXfkS+E9XwOLgUFIhWBG 3DZYtZnZ0biEwT0Kc7cA310ZFYxftYs1nQqAG6TsBvtpjqhy0Tpd167WQa8VWprS G+AqsroZ5TrGmL0lqCTu6X+0GJ5gLwfWhO/e+T4zpQT+JE69fxn1RtrqgSB+Rk3p 7qDYAgICmcEtMUiFBXQZ9N5SNg1fv7ACQ6dhEWRDW/tbT6BVnas+f3mtjhp7Asut /40jKQxPo+93KxYHa4dqjKfCOGqZqPDxcvsmHtRy0ddrr9R32E23O8EtpWSIsJyC lo7XoVAauvAhhewt0lEBgEgAMrEvwoqHDp/sdDJQdvZGIWs/6gc4w/2JLryZOQFn wbC2ynRU/I2Htri8nGnJMhZU85lIEj3o6C/+XAWa6wSwFR9KTW8BOvdoTXPMP1uy TZcs3WFQetti+VE= =+8op -----END PGP SIGNATURE----- Merge tag 'integrity-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity Pull integrity subsystem updates from Mimi Zohar: "Just three patches here. Other integrity changes are being upstreamed via EFI (defines a common EFI secure and trusted boot IMA policy) and BPF LSM (exporting the IMA file cache hash info based on inode). The three patches included here: - bug fix: fail calculating the file hash, when a file not opened for read and the attempt to re-open it for read fails. - defer processing the "ima_appraise" boot command line option to avoid enabling different modes (e.g. fix, log) to when the secure boot flag is available on arm. - defines "ima-buf" as the default IMA buffer measurement template in preparation for the builtin integrity "critical data" policy" * tag 'integrity-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity: ima: Don't modify file descriptor mode on the fly ima: select ima-buf template for buffer measurement ima: defer arch_ima_get_secureboot() call to IMA init time
959 lines
27 KiB
C
959 lines
27 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Integrity Measurement Architecture
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*
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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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* 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/kernel_read_file.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 <linux/iversion.h>
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#include <linux/fs.h>
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#include "ima.h"
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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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int ima_hash_algo = HASH_ALGO_SHA1;
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static int hash_setup_done;
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static struct notifier_block ima_lsm_policy_notifier = {
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.notifier_call = ima_lsm_policy_change,
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};
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static int __init hash_setup(char *str)
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{
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struct ima_template_desc *template_desc = ima_template_desc_current();
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int i;
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if (hash_setup_done)
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return 1;
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if (strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) == 0) {
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if (strncmp(str, "sha1", 4) == 0) {
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ima_hash_algo = HASH_ALGO_SHA1;
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} else if (strncmp(str, "md5", 3) == 0) {
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ima_hash_algo = HASH_ALGO_MD5;
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} else {
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pr_err("invalid hash algorithm \"%s\" for template \"%s\"",
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str, IMA_TEMPLATE_IMA_NAME);
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return 1;
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}
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goto out;
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}
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i = match_string(hash_algo_name, HASH_ALGO__LAST, str);
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if (i < 0) {
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pr_err("invalid hash algorithm \"%s\"", str);
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return 1;
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}
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ima_hash_algo = i;
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out:
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hash_setup_done = 1;
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return 1;
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}
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__setup("ima_hash=", hash_setup);
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/* Prevent mmap'ing a file execute that is already mmap'ed write */
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static int mmap_violation_check(enum ima_hooks func, struct file *file,
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char **pathbuf, const char **pathname,
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char *filename)
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{
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struct inode *inode;
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int rc = 0;
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if ((func == MMAP_CHECK) && mapping_writably_mapped(file->f_mapping)) {
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rc = -ETXTBSY;
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inode = file_inode(file);
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if (!*pathbuf) /* ima_rdwr_violation possibly pre-fetched */
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*pathname = ima_d_path(&file->f_path, pathbuf,
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filename);
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integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, *pathname,
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"mmap_file", "mmapped_writers", rc, 0);
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}
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return rc;
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}
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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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struct integrity_iint_cache *iint,
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int must_measure,
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char **pathbuf,
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const char **pathname,
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char *filename)
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{
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struct inode *inode = file_inode(file);
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fmode_t mode = file->f_mode;
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bool send_tomtou = false, send_writers = false;
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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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if (!iint)
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iint = integrity_iint_find(inode);
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/* IMA_MEASURE is set from reader side */
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if (iint && test_bit(IMA_MUST_MEASURE,
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&iint->atomic_flags))
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send_tomtou = true;
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}
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} else {
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if (must_measure)
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set_bit(IMA_MUST_MEASURE, &iint->atomic_flags);
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if (inode_is_open_for_write(inode) && must_measure)
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send_writers = true;
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}
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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, filename);
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if (send_tomtou)
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ima_add_violation(file, *pathname, iint,
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"invalid_pcr", "ToMToU");
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if (send_writers)
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ima_add_violation(file, *pathname, iint,
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"invalid_pcr", "open_writers");
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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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bool update;
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if (!(mode & FMODE_WRITE))
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return;
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mutex_lock(&iint->mutex);
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if (atomic_read(&inode->i_writecount) == 1) {
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update = test_and_clear_bit(IMA_UPDATE_XATTR,
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&iint->atomic_flags);
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if (!IS_I_VERSION(inode) ||
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!inode_eq_iversion(inode, iint->version) ||
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(iint->flags & IMA_NEW_FILE)) {
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iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE);
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iint->measured_pcrs = 0;
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if (update)
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ima_update_xattr(iint, file);
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}
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}
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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_inode(file);
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struct integrity_iint_cache *iint;
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if (!ima_policy_flag || !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 struct cred *cred,
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u32 secid, char *buf, loff_t size, int mask,
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enum ima_hooks func)
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{
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struct inode *inode = file_inode(file);
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struct integrity_iint_cache *iint = NULL;
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struct ima_template_desc *template_desc = NULL;
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char *pathbuf = NULL;
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char filename[NAME_MAX];
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const char *pathname = NULL;
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int rc = 0, action, must_appraise = 0;
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int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
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struct evm_ima_xattr_data *xattr_value = NULL;
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struct modsig *modsig = NULL;
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int xattr_len = 0;
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bool violation_check;
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enum hash_algo hash_algo;
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if (!ima_policy_flag || !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, cred, secid, mask, func, &pcr,
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&template_desc, NULL);
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violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) &&
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(ima_policy_flag & IMA_MEASURE));
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if (!action && !violation_check)
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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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if (action & IMA_FILE_APPRAISE)
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func = FILE_CHECK;
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inode_lock(inode);
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if (action) {
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iint = integrity_inode_get(inode);
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if (!iint)
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rc = -ENOMEM;
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}
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if (!rc && violation_check)
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ima_rdwr_violation_check(file, iint, action & IMA_MEASURE,
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&pathbuf, &pathname, filename);
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inode_unlock(inode);
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if (rc)
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goto out;
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if (!action)
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goto out;
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mutex_lock(&iint->mutex);
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if (test_and_clear_bit(IMA_CHANGE_ATTR, &iint->atomic_flags))
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/* reset appraisal flags if ima_inode_post_setattr was called */
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iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
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IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
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IMA_ACTION_FLAGS);
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/*
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* Re-evaulate the file if either the xattr has changed or the
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* kernel has no way of detecting file change on the filesystem.
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* (Limited to privileged mounted filesystems.)
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*/
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if (test_and_clear_bit(IMA_CHANGE_XATTR, &iint->atomic_flags) ||
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((inode->i_sb->s_iflags & SB_I_IMA_UNVERIFIABLE_SIGNATURE) &&
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!(inode->i_sb->s_iflags & SB_I_UNTRUSTED_MOUNTER) &&
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!(action & IMA_FAIL_UNVERIFIABLE_SIGS))) {
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iint->flags &= ~IMA_DONE_MASK;
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iint->measured_pcrs = 0;
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}
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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 ^ IMA_MEASURED)) >> 1);
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/* If target pcr is already measured, unset IMA_MEASURE action */
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if ((action & IMA_MEASURE) && (iint->measured_pcrs & (0x1 << pcr)))
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action ^= IMA_MEASURE;
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/* HASH sets the digital signature and update flags, nothing else */
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if ((action & IMA_HASH) &&
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!(test_bit(IMA_DIGSIG, &iint->atomic_flags))) {
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xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
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if ((xattr_value && xattr_len > 2) &&
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(xattr_value->type == EVM_IMA_XATTR_DIGSIG))
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set_bit(IMA_DIGSIG, &iint->atomic_flags);
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iint->flags |= IMA_HASHED;
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action ^= IMA_HASH;
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set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
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}
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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 = mmap_violation_check(func, file, &pathbuf,
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&pathname, filename);
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if (!rc)
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rc = ima_get_cache_status(iint, func);
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}
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goto out_locked;
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}
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if ((action & IMA_APPRAISE_SUBMASK) ||
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strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0) {
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/* read 'security.ima' */
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xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
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/*
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* Read the appended modsig if allowed by the policy, and allow
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* an additional measurement list entry, if needed, based on the
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* template format and whether the file was already measured.
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*/
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if (iint->flags & IMA_MODSIG_ALLOWED) {
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rc = ima_read_modsig(func, buf, size, &modsig);
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if (!rc && ima_template_has_modsig(template_desc) &&
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iint->flags & IMA_MEASURED)
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action |= IMA_MEASURE;
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}
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}
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hash_algo = ima_get_hash_algo(xattr_value, xattr_len);
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rc = ima_collect_measurement(iint, file, buf, size, hash_algo, modsig);
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if (rc != 0 && rc != -EBADF && rc != -EINVAL)
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goto out_locked;
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if (!pathbuf) /* ima_rdwr_violation possibly pre-fetched */
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pathname = ima_d_path(&file->f_path, &pathbuf, filename);
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if (action & IMA_MEASURE)
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ima_store_measurement(iint, file, pathname,
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xattr_value, xattr_len, modsig, pcr,
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template_desc);
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if (rc == 0 && (action & IMA_APPRAISE_SUBMASK)) {
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rc = ima_check_blacklist(iint, modsig, pcr);
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if (rc != -EPERM) {
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inode_lock(inode);
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rc = ima_appraise_measurement(func, iint, file,
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pathname, xattr_value,
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xattr_len, modsig);
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inode_unlock(inode);
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}
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if (!rc)
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rc = mmap_violation_check(func, file, &pathbuf,
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&pathname, filename);
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}
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if (action & IMA_AUDIT)
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ima_audit_measurement(iint, pathname);
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if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO))
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rc = 0;
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out_locked:
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if ((mask & MAY_WRITE) && test_bit(IMA_DIGSIG, &iint->atomic_flags) &&
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!(iint->flags & IMA_NEW_FILE))
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rc = -EACCES;
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mutex_unlock(&iint->mutex);
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kfree(xattr_value);
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ima_free_modsig(modsig);
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out:
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if (pathbuf)
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__putname(pathbuf);
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if (must_appraise) {
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if (rc && (ima_appraise & IMA_APPRAISE_ENFORCE))
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return -EACCES;
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if (file->f_mode & FMODE_WRITE)
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set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
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}
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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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u32 secid;
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if (file && (prot & PROT_EXEC)) {
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security_task_getsecid(current, &secid);
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return process_measurement(file, current_cred(), secid, NULL,
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0, MAY_EXEC, MMAP_CHECK);
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}
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return 0;
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}
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/**
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* ima_file_mprotect - based on policy, limit mprotect change
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* @prot: contains the protection that will be applied by the kernel.
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*
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* Files can be mmap'ed read/write and later changed to execute to circumvent
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* IMA's mmap appraisal policy rules. Due to locking issues (mmap semaphore
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* would be taken before i_mutex), files can not be measured or appraised at
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* this point. Eliminate this integrity gap by denying the mprotect
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* PROT_EXECUTE change, if an mmap appraise policy rule exists.
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*
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* On mprotect change success, return 0. On failure, return -EACESS.
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*/
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int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot)
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{
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struct ima_template_desc *template = NULL;
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struct file *file = vma->vm_file;
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char filename[NAME_MAX];
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char *pathbuf = NULL;
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const char *pathname = NULL;
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struct inode *inode;
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int result = 0;
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int action;
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u32 secid;
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int pcr;
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/* Is mprotect making an mmap'ed file executable? */
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|
if (!(ima_policy_flag & IMA_APPRAISE) || !vma->vm_file ||
|
|
!(prot & PROT_EXEC) || (vma->vm_flags & VM_EXEC))
|
|
return 0;
|
|
|
|
security_task_getsecid(current, &secid);
|
|
inode = file_inode(vma->vm_file);
|
|
action = ima_get_action(inode, current_cred(), secid, MAY_EXEC,
|
|
MMAP_CHECK, &pcr, &template, 0);
|
|
|
|
/* Is the mmap'ed file in policy? */
|
|
if (!(action & (IMA_MEASURE | IMA_APPRAISE_SUBMASK)))
|
|
return 0;
|
|
|
|
if (action & IMA_APPRAISE_SUBMASK)
|
|
result = -EPERM;
|
|
|
|
file = vma->vm_file;
|
|
pathname = ima_d_path(&file->f_path, &pathbuf, filename);
|
|
integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, pathname,
|
|
"collect_data", "failed-mprotect", result, 0);
|
|
if (pathbuf)
|
|
__putname(pathbuf);
|
|
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* 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);
|
|
|
|
static int __ima_inode_hash(struct inode *inode, char *buf, size_t buf_size)
|
|
{
|
|
struct integrity_iint_cache *iint;
|
|
int hash_algo;
|
|
|
|
if (!ima_policy_flag)
|
|
return -EOPNOTSUPP;
|
|
|
|
iint = integrity_iint_find(inode);
|
|
if (!iint)
|
|
return -EOPNOTSUPP;
|
|
|
|
mutex_lock(&iint->mutex);
|
|
|
|
/*
|
|
* ima_file_hash can be called when ima_collect_measurement has still
|
|
* not been called, we might not always have a hash.
|
|
*/
|
|
if (!iint->ima_hash) {
|
|
mutex_unlock(&iint->mutex);
|
|
return -EOPNOTSUPP;
|
|
}
|
|
|
|
if (buf) {
|
|
size_t copied_size;
|
|
|
|
copied_size = min_t(size_t, iint->ima_hash->length, buf_size);
|
|
memcpy(buf, iint->ima_hash->digest, copied_size);
|
|
}
|
|
hash_algo = iint->ima_hash->algo;
|
|
mutex_unlock(&iint->mutex);
|
|
|
|
return hash_algo;
|
|
}
|
|
|
|
/**
|
|
* ima_file_hash - return the stored measurement if a file has been hashed and
|
|
* is in the iint cache.
|
|
* @file: pointer to the file
|
|
* @buf: buffer in which to store the hash
|
|
* @buf_size: length of the buffer
|
|
*
|
|
* On success, return the hash algorithm (as defined in the enum hash_algo).
|
|
* If buf is not NULL, this function also outputs the hash into buf.
|
|
* If the hash is larger than buf_size, then only buf_size bytes will be copied.
|
|
* It generally just makes sense to pass a buffer capable of holding the largest
|
|
* possible hash: IMA_MAX_DIGEST_SIZE.
|
|
* The file hash returned is based on the entire file, including the appended
|
|
* signature.
|
|
*
|
|
* If IMA is disabled or if no measurement is available, return -EOPNOTSUPP.
|
|
* If the parameters are incorrect, return -EINVAL.
|
|
*/
|
|
int ima_file_hash(struct file *file, char *buf, size_t buf_size)
|
|
{
|
|
if (!file)
|
|
return -EINVAL;
|
|
|
|
return __ima_inode_hash(file_inode(file), buf, buf_size);
|
|
}
|
|
EXPORT_SYMBOL_GPL(ima_file_hash);
|
|
|
|
/**
|
|
* ima_inode_hash - return the stored measurement if the inode has been hashed
|
|
* and is in the iint cache.
|
|
* @inode: pointer to the inode
|
|
* @buf: buffer in which to store the hash
|
|
* @buf_size: length of the buffer
|
|
*
|
|
* On success, return the hash algorithm (as defined in the enum hash_algo).
|
|
* If buf is not NULL, this function also outputs the hash into buf.
|
|
* If the hash is larger than buf_size, then only buf_size bytes will be copied.
|
|
* It generally just makes sense to pass a buffer capable of holding the largest
|
|
* possible hash: IMA_MAX_DIGEST_SIZE.
|
|
* The hash returned is based on the entire contents, including the appended
|
|
* signature.
|
|
*
|
|
* If IMA is disabled or if no measurement is available, return -EOPNOTSUPP.
|
|
* If the parameters are incorrect, return -EINVAL.
|
|
*/
|
|
int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size)
|
|
{
|
|
if (!inode)
|
|
return -EINVAL;
|
|
|
|
return __ima_inode_hash(inode, buf, buf_size);
|
|
}
|
|
EXPORT_SYMBOL_GPL(ima_inode_hash);
|
|
|
|
/**
|
|
* 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
|
|
* @contents: whether a subsequent call will be made to ima_post_read_file()
|
|
*
|
|
* 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,
|
|
bool contents)
|
|
{
|
|
enum ima_hooks func;
|
|
u32 secid;
|
|
|
|
/*
|
|
* 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? It may be desirable to include the buffer address
|
|
* in this API and walk all the dma_map_single() mappings to check.
|
|
*/
|
|
|
|
/*
|
|
* There will be a call made to ima_post_read_file() with
|
|
* a filled buffer, so we don't need to perform an extra
|
|
* read early here.
|
|
*/
|
|
if (contents)
|
|
return 0;
|
|
|
|
/* Read entire file for all partial reads. */
|
|
func = read_idmap[read_id] ?: FILE_CHECK;
|
|
security_task_getsecid(current, &secid);
|
|
return process_measurement(file, current_cred(), secid, NULL,
|
|
0, MAY_READ, func);
|
|
}
|
|
|
|
const int read_idmap[READING_MAX_ID] = {
|
|
[READING_FIRMWARE] = 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;
|
|
|
|
/* 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
|
|
* @contents: whether the full contents will be available in a later
|
|
* call to ima_post_load_data().
|
|
*
|
|
* 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 contents)
|
|
{
|
|
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_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) && !contents) {
|
|
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;
|
|
}
|
|
|
|
/**
|
|
* ima_post_load_data - appraise decision based on policy
|
|
* @buf: pointer to in memory file contents
|
|
* @size: size of in memory file contents
|
|
* @id: kernel load data caller identifier
|
|
* @description: @id-specific description of contents
|
|
*
|
|
* Measure/appraise/audit in memory buffer 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_load_data(char *buf, loff_t size,
|
|
enum kernel_load_data_id load_id,
|
|
char *description)
|
|
{
|
|
if (load_id == LOADING_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;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* process_buffer_measurement - Measure the buffer to ima log.
|
|
* @inode: inode associated with the object being measured (NULL for KEY_CHECK)
|
|
* @buf: pointer to the buffer that needs to be added to the log.
|
|
* @size: size of buffer(in bytes).
|
|
* @eventname: event name to be used for the buffer entry.
|
|
* @func: IMA hook
|
|
* @pcr: pcr to extend the measurement
|
|
* @keyring: keyring name to determine the action to be performed
|
|
*
|
|
* Based on policy, the buffer is measured into the ima log.
|
|
*/
|
|
void process_buffer_measurement(struct inode *inode, const void *buf, int size,
|
|
const char *eventname, enum ima_hooks func,
|
|
int pcr, const char *keyring)
|
|
{
|
|
int ret = 0;
|
|
const char *audit_cause = "ENOMEM";
|
|
struct ima_template_entry *entry = NULL;
|
|
struct integrity_iint_cache iint = {};
|
|
struct ima_event_data event_data = {.iint = &iint,
|
|
.filename = eventname,
|
|
.buf = buf,
|
|
.buf_len = size};
|
|
struct ima_template_desc *template;
|
|
struct {
|
|
struct ima_digest_data hdr;
|
|
char digest[IMA_MAX_DIGEST_SIZE];
|
|
} hash = {};
|
|
int violation = 0;
|
|
int action = 0;
|
|
u32 secid;
|
|
|
|
if (!ima_policy_flag)
|
|
return;
|
|
|
|
template = ima_template_desc_buf();
|
|
if (!template) {
|
|
ret = -EINVAL;
|
|
audit_cause = "ima_template_desc_buf";
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* Both LSM hooks and auxilary based buffer measurements are
|
|
* based on policy. To avoid code duplication, differentiate
|
|
* between the LSM hooks and auxilary buffer measurements,
|
|
* retrieving the policy rule information only for the LSM hook
|
|
* buffer measurements.
|
|
*/
|
|
if (func) {
|
|
security_task_getsecid(current, &secid);
|
|
action = ima_get_action(inode, current_cred(), secid, 0, func,
|
|
&pcr, &template, keyring);
|
|
if (!(action & IMA_MEASURE))
|
|
return;
|
|
}
|
|
|
|
if (!pcr)
|
|
pcr = CONFIG_IMA_MEASURE_PCR_IDX;
|
|
|
|
iint.ima_hash = &hash.hdr;
|
|
iint.ima_hash->algo = ima_hash_algo;
|
|
iint.ima_hash->length = hash_digest_size[ima_hash_algo];
|
|
|
|
ret = ima_calc_buffer_hash(buf, size, iint.ima_hash);
|
|
if (ret < 0) {
|
|
audit_cause = "hashing_error";
|
|
goto out;
|
|
}
|
|
|
|
ret = ima_alloc_init_template(&event_data, &entry, template);
|
|
if (ret < 0) {
|
|
audit_cause = "alloc_entry";
|
|
goto out;
|
|
}
|
|
|
|
ret = ima_store_template(entry, violation, NULL, buf, pcr);
|
|
if (ret < 0) {
|
|
audit_cause = "store_entry";
|
|
ima_free_template_entry(entry);
|
|
}
|
|
|
|
out:
|
|
if (ret < 0)
|
|
integrity_audit_message(AUDIT_INTEGRITY_PCR, NULL, eventname,
|
|
func_measure_str(func),
|
|
audit_cause, ret, 0, ret);
|
|
|
|
return;
|
|
}
|
|
|
|
/**
|
|
* ima_kexec_cmdline - measure kexec cmdline boot args
|
|
* @kernel_fd: file descriptor of the kexec kernel being loaded
|
|
* @buf: pointer to buffer
|
|
* @size: size of buffer
|
|
*
|
|
* Buffers can only be measured, not appraised.
|
|
*/
|
|
void ima_kexec_cmdline(int kernel_fd, const void *buf, int size)
|
|
{
|
|
struct fd f;
|
|
|
|
if (!buf || !size)
|
|
return;
|
|
|
|
f = fdget(kernel_fd);
|
|
if (!f.file)
|
|
return;
|
|
|
|
process_buffer_measurement(file_inode(f.file), buf, size,
|
|
"kexec-cmdline", KEXEC_CMDLINE, 0, NULL);
|
|
fdput(f);
|
|
}
|
|
|
|
static int __init init_ima(void)
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{
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int error;
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ima_appraise_parse_cmdline();
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ima_init_template_list();
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hash_setup(CONFIG_IMA_DEFAULT_HASH);
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error = ima_init();
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if (error && strcmp(hash_algo_name[ima_hash_algo],
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CONFIG_IMA_DEFAULT_HASH) != 0) {
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pr_info("Allocating %s failed, going to use default hash algorithm %s\n",
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hash_algo_name[ima_hash_algo], CONFIG_IMA_DEFAULT_HASH);
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hash_setup_done = 0;
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hash_setup(CONFIG_IMA_DEFAULT_HASH);
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error = ima_init();
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}
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if (error)
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return error;
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error = register_blocking_lsm_notifier(&ima_lsm_policy_notifier);
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if (error)
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pr_warn("Couldn't register LSM notifier, error %d\n", error);
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if (!error)
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ima_update_policy_flag();
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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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