summaryrefslogtreecommitdiffstats
path: root/security/integrity/ima/ima_main.c
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--security/integrity/ima/ima_main.c1100
1 files changed, 1100 insertions, 0 deletions
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
new file mode 100644
index 000000000..185666d90
--- /dev/null
+++ b/security/integrity/ima/ima_main.c
@@ -0,0 +1,1100 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Integrity Measurement Architecture
+ *
+ * Copyright (C) 2005,2006,2007,2008 IBM Corporation
+ *
+ * Authors:
+ * Reiner Sailer <sailer@watson.ibm.com>
+ * Serge Hallyn <serue@us.ibm.com>
+ * Kylene Hall <kylene@us.ibm.com>
+ * Mimi Zohar <zohar@us.ibm.com>
+ *
+ * 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/kernel_read_file.h>
+#include <linux/mount.h>
+#include <linux/mman.h>
+#include <linux/slab.h>
+#include <linux/xattr.h>
+#include <linux/ima.h>
+#include <linux/iversion.h>
+#include <linux/fs.h>
+#include <linux/iversion.h>
+
+#include "ima.h"
+
+#ifdef CONFIG_IMA_APPRAISE
+int ima_appraise = IMA_APPRAISE_ENFORCE;
+#else
+int ima_appraise;
+#endif
+
+int __ro_after_init ima_hash_algo = HASH_ALGO_SHA1;
+static int hash_setup_done;
+
+static struct notifier_block ima_lsm_policy_notifier = {
+ .notifier_call = ima_lsm_policy_change,
+};
+
+static int __init hash_setup(char *str)
+{
+ struct ima_template_desc *template_desc = ima_template_desc_current();
+ int i;
+
+ if (hash_setup_done)
+ return 1;
+
+ if (strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) == 0) {
+ if (strncmp(str, "sha1", 4) == 0) {
+ ima_hash_algo = HASH_ALGO_SHA1;
+ } else if (strncmp(str, "md5", 3) == 0) {
+ ima_hash_algo = HASH_ALGO_MD5;
+ } else {
+ pr_err("invalid hash algorithm \"%s\" for template \"%s\"",
+ str, IMA_TEMPLATE_IMA_NAME);
+ return 1;
+ }
+ goto out;
+ }
+
+ i = match_string(hash_algo_name, HASH_ALGO__LAST, str);
+ if (i < 0) {
+ pr_err("invalid hash algorithm \"%s\"", str);
+ return 1;
+ }
+
+ ima_hash_algo = i;
+out:
+ hash_setup_done = 1;
+ return 1;
+}
+__setup("ima_hash=", hash_setup);
+
+enum hash_algo ima_get_current_hash_algo(void)
+{
+ return ima_hash_algo;
+}
+
+/* Prevent mmap'ing a file execute that is already mmap'ed write */
+static int mmap_violation_check(enum ima_hooks func, struct file *file,
+ char **pathbuf, const char **pathname,
+ char *filename)
+{
+ struct inode *inode;
+ int rc = 0;
+
+ if ((func == MMAP_CHECK) && mapping_writably_mapped(file->f_mapping)) {
+ rc = -ETXTBSY;
+ inode = file_inode(file);
+
+ if (!*pathbuf) /* ima_rdwr_violation possibly pre-fetched */
+ *pathname = ima_d_path(&file->f_path, pathbuf,
+ filename);
+ integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, *pathname,
+ "mmap_file", "mmapped_writers", rc, 0);
+ }
+ return rc;
+}
+
+/*
+ * ima_rdwr_violation_check
+ *
+ * Only invalidate the PCR for measured files:
+ * - Opening a file for write when already open for read,
+ * results in a time of measure, time of use (ToMToU) error.
+ * - Opening a file for read when already open for write,
+ * could result in a file measurement error.
+ *
+ */
+static void ima_rdwr_violation_check(struct file *file,
+ struct integrity_iint_cache *iint,
+ int must_measure,
+ char **pathbuf,
+ const char **pathname,
+ char *filename)
+{
+ struct inode *inode = file_inode(file);
+ fmode_t mode = file->f_mode;
+ bool send_tomtou = false, send_writers = false;
+
+ if (mode & FMODE_WRITE) {
+ if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) {
+ if (!iint)
+ iint = integrity_iint_find(inode);
+ /* IMA_MEASURE is set from reader side */
+ if (iint && test_bit(IMA_MUST_MEASURE,
+ &iint->atomic_flags))
+ send_tomtou = true;
+ }
+ } else {
+ if (must_measure)
+ set_bit(IMA_MUST_MEASURE, &iint->atomic_flags);
+ if (inode_is_open_for_write(inode) && must_measure)
+ send_writers = true;
+ }
+
+ if (!send_tomtou && !send_writers)
+ return;
+
+ *pathname = ima_d_path(&file->f_path, pathbuf, filename);
+
+ if (send_tomtou)
+ ima_add_violation(file, *pathname, iint,
+ "invalid_pcr", "ToMToU");
+ if (send_writers)
+ ima_add_violation(file, *pathname, iint,
+ "invalid_pcr", "open_writers");
+}
+
+static void ima_check_last_writer(struct integrity_iint_cache *iint,
+ struct inode *inode, struct file *file)
+{
+ fmode_t mode = file->f_mode;
+ bool update;
+
+ if (!(mode & FMODE_WRITE))
+ return;
+
+ mutex_lock(&iint->mutex);
+ if (atomic_read(&inode->i_writecount) == 1) {
+ update = test_and_clear_bit(IMA_UPDATE_XATTR,
+ &iint->atomic_flags);
+ if (!IS_I_VERSION(inode) ||
+ !inode_eq_iversion(inode, iint->version) ||
+ (iint->flags & IMA_NEW_FILE)) {
+ iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE);
+ iint->measured_pcrs = 0;
+ if (update)
+ ima_update_xattr(iint, file);
+ }
+ }
+ mutex_unlock(&iint->mutex);
+}
+
+/**
+ * ima_file_free - called on __fput()
+ * @file: pointer to file structure being freed
+ *
+ * Flag files that changed, based on i_version
+ */
+void ima_file_free(struct file *file)
+{
+ struct inode *inode = file_inode(file);
+ struct integrity_iint_cache *iint;
+
+ if (!ima_policy_flag || !S_ISREG(inode->i_mode))
+ return;
+
+ iint = integrity_iint_find(inode);
+ if (!iint)
+ return;
+
+ ima_check_last_writer(iint, inode, file);
+}
+
+static int process_measurement(struct file *file, const struct cred *cred,
+ u32 secid, char *buf, loff_t size, int mask,
+ enum ima_hooks func)
+{
+ struct inode *backing_inode, *inode = file_inode(file);
+ struct integrity_iint_cache *iint = NULL;
+ struct ima_template_desc *template_desc = NULL;
+ char *pathbuf = NULL;
+ char filename[NAME_MAX];
+ const char *pathname = NULL;
+ int rc = 0, action, must_appraise = 0;
+ int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
+ struct evm_ima_xattr_data *xattr_value = NULL;
+ struct modsig *modsig = NULL;
+ int xattr_len = 0;
+ bool violation_check;
+ enum hash_algo hash_algo;
+ unsigned int allowed_algos = 0;
+
+ 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(file_mnt_user_ns(file), inode, cred, secid,
+ mask, func, &pcr, &template_desc, NULL,
+ &allowed_algos);
+ violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) &&
+ (ima_policy_flag & IMA_MEASURE));
+ if (!action && !violation_check)
+ return 0;
+
+ must_appraise = action & IMA_APPRAISE;
+
+ /* Is the appraise rule hook specific? */
+ if (action & IMA_FILE_APPRAISE)
+ func = FILE_CHECK;
+
+ inode_lock(inode);
+
+ if (action) {
+ iint = integrity_inode_get(inode);
+ if (!iint)
+ rc = -ENOMEM;
+ }
+
+ if (!rc && violation_check)
+ ima_rdwr_violation_check(file, iint, action & IMA_MEASURE,
+ &pathbuf, &pathname, filename);
+
+ inode_unlock(inode);
+
+ if (rc)
+ goto out;
+ if (!action)
+ goto out;
+
+ mutex_lock(&iint->mutex);
+
+ if (test_and_clear_bit(IMA_CHANGE_ATTR, &iint->atomic_flags))
+ /* reset appraisal flags if ima_inode_post_setattr was called */
+ iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
+ IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
+ IMA_NONACTION_FLAGS);
+
+ /*
+ * Re-evaulate the file if either the xattr has changed or the
+ * kernel has no way of detecting file change on the filesystem.
+ * (Limited to privileged mounted filesystems.)
+ */
+ if (test_and_clear_bit(IMA_CHANGE_XATTR, &iint->atomic_flags) ||
+ ((inode->i_sb->s_iflags & SB_I_IMA_UNVERIFIABLE_SIGNATURE) &&
+ !(inode->i_sb->s_iflags & SB_I_UNTRUSTED_MOUNTER) &&
+ !(action & IMA_FAIL_UNVERIFIABLE_SIGS))) {
+ iint->flags &= ~IMA_DONE_MASK;
+ iint->measured_pcrs = 0;
+ }
+
+ /* Detect and re-evaluate changes made to the backing file. */
+ backing_inode = d_real_inode(file_dentry(file));
+ if (backing_inode != inode &&
+ (action & IMA_DO_MASK) && (iint->flags & IMA_DONE_MASK)) {
+ if (!IS_I_VERSION(backing_inode) ||
+ backing_inode->i_sb->s_dev != iint->real_dev ||
+ backing_inode->i_ino != iint->real_ino ||
+ !inode_eq_iversion(backing_inode, iint->version)) {
+ iint->flags &= ~IMA_DONE_MASK;
+ iint->measured_pcrs = 0;
+ }
+ }
+
+ /* Determine if already appraised/measured based on bitmask
+ * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
+ * IMA_AUDIT, IMA_AUDITED)
+ */
+ iint->flags |= action;
+ action &= IMA_DO_MASK;
+ action &= ~((iint->flags & (IMA_DONE_MASK ^ IMA_MEASURED)) >> 1);
+
+ /* If target pcr is already measured, unset IMA_MEASURE action */
+ if ((action & IMA_MEASURE) && (iint->measured_pcrs & (0x1 << pcr)))
+ action ^= IMA_MEASURE;
+
+ /* HASH sets the digital signature and update flags, nothing else */
+ if ((action & IMA_HASH) &&
+ !(test_bit(IMA_DIGSIG, &iint->atomic_flags))) {
+ xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
+ if ((xattr_value && xattr_len > 2) &&
+ (xattr_value->type == EVM_IMA_XATTR_DIGSIG))
+ set_bit(IMA_DIGSIG, &iint->atomic_flags);
+ iint->flags |= IMA_HASHED;
+ action ^= IMA_HASH;
+ set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
+ }
+
+ /* Nothing to do, just return existing appraised status */
+ if (!action) {
+ if (must_appraise) {
+ rc = mmap_violation_check(func, file, &pathbuf,
+ &pathname, filename);
+ if (!rc)
+ rc = ima_get_cache_status(iint, func);
+ }
+ goto out_locked;
+ }
+
+ if ((action & IMA_APPRAISE_SUBMASK) ||
+ strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0) {
+ /* read 'security.ima' */
+ xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
+
+ /*
+ * Read the appended modsig if allowed by the policy, and allow
+ * an additional measurement list entry, if needed, based on the
+ * template format and whether the file was already measured.
+ */
+ if (iint->flags & IMA_MODSIG_ALLOWED) {
+ rc = ima_read_modsig(func, buf, size, &modsig);
+
+ if (!rc && ima_template_has_modsig(template_desc) &&
+ iint->flags & IMA_MEASURED)
+ action |= IMA_MEASURE;
+ }
+ }
+
+ hash_algo = ima_get_hash_algo(xattr_value, xattr_len);
+
+ rc = ima_collect_measurement(iint, file, buf, size, hash_algo, modsig);
+ if (rc != 0 && rc != -EBADF && rc != -EINVAL)
+ goto out_locked;
+
+ if (!pathbuf) /* ima_rdwr_violation possibly pre-fetched */
+ pathname = ima_d_path(&file->f_path, &pathbuf, filename);
+
+ if (action & IMA_MEASURE)
+ ima_store_measurement(iint, file, pathname,
+ xattr_value, xattr_len, modsig, pcr,
+ template_desc);
+ if (rc == 0 && (action & IMA_APPRAISE_SUBMASK)) {
+ rc = ima_check_blacklist(iint, modsig, pcr);
+ if (rc != -EPERM) {
+ inode_lock(inode);
+ rc = ima_appraise_measurement(func, iint, file,
+ pathname, xattr_value,
+ xattr_len, modsig);
+ inode_unlock(inode);
+ }
+ if (!rc)
+ rc = mmap_violation_check(func, file, &pathbuf,
+ &pathname, filename);
+ }
+ if (action & IMA_AUDIT)
+ ima_audit_measurement(iint, pathname);
+
+ if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO))
+ rc = 0;
+
+ /* Ensure the digest was generated using an allowed algorithm */
+ if (rc == 0 && must_appraise && allowed_algos != 0 &&
+ (allowed_algos & (1U << hash_algo)) == 0) {
+ rc = -EACCES;
+
+ integrity_audit_msg(AUDIT_INTEGRITY_DATA, file_inode(file),
+ pathname, "collect_data",
+ "denied-hash-algorithm", rc, 0);
+ }
+out_locked:
+ if ((mask & MAY_WRITE) && test_bit(IMA_DIGSIG, &iint->atomic_flags) &&
+ !(iint->flags & IMA_NEW_FILE))
+ rc = -EACCES;
+ mutex_unlock(&iint->mutex);
+ kfree(xattr_value);
+ ima_free_modsig(modsig);
+out:
+ if (pathbuf)
+ __putname(pathbuf);
+ if (must_appraise) {
+ if (rc && (ima_appraise & IMA_APPRAISE_ENFORCE))
+ return -EACCES;
+ if (file->f_mode & FMODE_WRITE)
+ set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
+ }
+ return 0;
+}
+
+/**
+ * ima_file_mmap - based on policy, collect/store measurement.
+ * @file: pointer to the file to be measured (May be NULL)
+ * @reqprot: protection requested by the application
+ * @prot: protection that will be applied by the kernel
+ * @flags: operational flags
+ *
+ * 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 reqprot,
+ unsigned long prot, unsigned long flags)
+{
+ u32 secid;
+
+ if (file && (prot & PROT_EXEC)) {
+ security_current_getsecid_subj(&secid);
+ return process_measurement(file, current_cred(), secid, NULL,
+ 0, MAY_EXEC, MMAP_CHECK);
+ }
+
+ return 0;
+}
+
+/**
+ * ima_file_mprotect - based on policy, limit mprotect change
+ * @vma: vm_area_struct protection is set to
+ * @prot: contains the protection that will be applied by the kernel.
+ *
+ * Files can be mmap'ed read/write and later changed to execute to circumvent
+ * IMA's mmap appraisal policy rules. Due to locking issues (mmap semaphore
+ * would be taken before i_mutex), files can not be measured or appraised at
+ * this point. Eliminate this integrity gap by denying the mprotect
+ * PROT_EXECUTE change, if an mmap appraise policy rule exists.
+ *
+ * On mprotect change success, return 0. On failure, return -EACESS.
+ */
+int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot)
+{
+ struct ima_template_desc *template = NULL;
+ struct file *file;
+ char filename[NAME_MAX];
+ char *pathbuf = NULL;
+ const char *pathname = NULL;
+ struct inode *inode;
+ int result = 0;
+ int action;
+ u32 secid;
+ int pcr;
+
+ /* Is mprotect making an mmap'ed file executable? */
+ if (!(ima_policy_flag & IMA_APPRAISE) || !vma->vm_file ||
+ !(prot & PROT_EXEC) || (vma->vm_flags & VM_EXEC))
+ return 0;
+
+ security_current_getsecid_subj(&secid);
+ inode = file_inode(vma->vm_file);
+ action = ima_get_action(file_mnt_user_ns(vma->vm_file), inode,
+ current_cred(), secid, MAY_EXEC, MMAP_CHECK,
+ &pcr, &template, NULL, NULL);
+
+ /* 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_current_getsecid_subj(&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_file_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_current_getsecid_subj(&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, struct file *file, char *buf,
+ size_t buf_size)
+{
+ struct integrity_iint_cache *iint = NULL, tmp_iint;
+ int rc, hash_algo;
+
+ if (ima_policy_flag) {
+ iint = integrity_iint_find(inode);
+ if (iint)
+ mutex_lock(&iint->mutex);
+ }
+
+ if ((!iint || !(iint->flags & IMA_COLLECTED)) && file) {
+ if (iint)
+ mutex_unlock(&iint->mutex);
+
+ memset(&tmp_iint, 0, sizeof(tmp_iint));
+ tmp_iint.inode = inode;
+ mutex_init(&tmp_iint.mutex);
+
+ rc = ima_collect_measurement(&tmp_iint, file, NULL, 0,
+ ima_hash_algo, NULL);
+ if (rc < 0) {
+ /* ima_hash could be allocated in case of failure. */
+ if (rc != -ENOMEM)
+ kfree(tmp_iint.ima_hash);
+
+ return -EOPNOTSUPP;
+ }
+
+ iint = &tmp_iint;
+ mutex_lock(&iint->mutex);
+ }
+
+ if (!iint)
+ return -EOPNOTSUPP;
+
+ /*
+ * 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);
+
+ if (iint == &tmp_iint)
+ kfree(iint->ima_hash);
+
+ return hash_algo;
+}
+
+/**
+ * ima_file_hash - return a measurement of the file
+ * @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 the measurement cannot be performed, 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), 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, NULL, buf, buf_size);
+}
+EXPORT_SYMBOL_GPL(ima_inode_hash);
+
+/**
+ * ima_post_create_tmpfile - mark newly created tmpfile as new
+ * @mnt_userns: user namespace of the mount the inode was found from
+ * @inode: inode of the 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 user_namespace *mnt_userns,
+ struct inode *inode)
+{
+ struct integrity_iint_cache *iint;
+ int must_appraise;
+
+ if (!ima_policy_flag || !S_ISREG(inode->i_mode))
+ return;
+
+ must_appraise = ima_must_appraise(mnt_userns, 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
+ * @mnt_userns: user namespace of the mount the inode was found from
+ * @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 user_namespace *mnt_userns,
+ struct dentry *dentry)
+{
+ struct integrity_iint_cache *iint;
+ struct inode *inode = dentry->d_inode;
+ int must_appraise;
+
+ if (!ima_policy_flag || !S_ISREG(inode->i_mode))
+ return;
+
+ must_appraise = ima_must_appraise(mnt_userns, 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_current_getsecid_subj(&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_current_getsecid_subj(&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 requiring 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 */
+ }
+ break;
+ 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
+ * @load_id: kernel load data caller identifier
+ * @description: @load_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 or the buffer data hash
+ * @mnt_userns: user namespace of the mount the inode was found from
+ * @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
+ * @func_data: func specific data, may be NULL
+ * @buf_hash: measure buffer data hash
+ * @digest: buffer digest will be written to
+ * @digest_len: buffer length
+ *
+ * Based on policy, either the buffer data or buffer data hash is measured
+ *
+ * Return: 0 if the buffer has been successfully measured, 1 if the digest
+ * has been written to the passed location but not added to a measurement entry,
+ * a negative value otherwise.
+ */
+int process_buffer_measurement(struct user_namespace *mnt_userns,
+ struct inode *inode, const void *buf, int size,
+ const char *eventname, enum ima_hooks func,
+ int pcr, const char *func_data,
+ bool buf_hash, u8 *digest, size_t digest_len)
+{
+ 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 ima_max_digest_data hash;
+ char digest_hash[IMA_MAX_DIGEST_SIZE];
+ int digest_hash_len = hash_digest_size[ima_hash_algo];
+ int violation = 0;
+ int action = 0;
+ u32 secid;
+
+ if (digest && digest_len < digest_hash_len)
+ return -EINVAL;
+
+ if (!ima_policy_flag && !digest)
+ return -ENOENT;
+
+ 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_current_getsecid_subj(&secid);
+ action = ima_get_action(mnt_userns, inode, current_cred(),
+ secid, 0, func, &pcr, &template,
+ func_data, NULL);
+ if (!(action & IMA_MEASURE) && !digest)
+ return -ENOENT;
+ }
+
+ 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;
+ }
+
+ if (buf_hash) {
+ memcpy(digest_hash, hash.hdr.digest, digest_hash_len);
+
+ ret = ima_calc_buffer_hash(digest_hash, digest_hash_len,
+ iint.ima_hash);
+ if (ret < 0) {
+ audit_cause = "hashing_error";
+ goto out;
+ }
+
+ event_data.buf = digest_hash;
+ event_data.buf_len = digest_hash_len;
+ }
+
+ if (digest)
+ memcpy(digest, iint.ima_hash->digest, digest_hash_len);
+
+ if (!ima_policy_flag || (func && !(action & IMA_MEASURE)))
+ return 1;
+
+ 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, event_data.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 ret;
+}
+
+/**
+ * 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_mnt_user_ns(f.file), file_inode(f.file),
+ buf, size, "kexec-cmdline", KEXEC_CMDLINE, 0,
+ NULL, false, NULL, 0);
+ fdput(f);
+}
+
+/**
+ * ima_measure_critical_data - measure kernel integrity critical data
+ * @event_label: unique event label for grouping and limiting critical data
+ * @event_name: event name for the record in the IMA measurement list
+ * @buf: pointer to buffer data
+ * @buf_len: length of buffer data (in bytes)
+ * @hash: measure buffer data hash
+ * @digest: buffer digest will be written to
+ * @digest_len: buffer length
+ *
+ * Measure data critical to the integrity of the kernel into the IMA log
+ * and extend the pcr. Examples of critical data could be various data
+ * structures, policies, and states stored in kernel memory that can
+ * impact the integrity of the system.
+ *
+ * Return: 0 if the buffer has been successfully measured, 1 if the digest
+ * has been written to the passed location but not added to a measurement entry,
+ * a negative value otherwise.
+ */
+int ima_measure_critical_data(const char *event_label,
+ const char *event_name,
+ const void *buf, size_t buf_len,
+ bool hash, u8 *digest, size_t digest_len)
+{
+ if (!event_name || !event_label || !buf || !buf_len)
+ return -ENOPARAM;
+
+ return process_buffer_measurement(&init_user_ns, NULL, buf, buf_len,
+ event_name, CRITICAL_DATA, 0,
+ event_label, hash, digest,
+ digest_len);
+}
+EXPORT_SYMBOL_GPL(ima_measure_critical_data);
+
+static int __init init_ima(void)
+{
+ int error;
+
+ ima_appraise_parse_cmdline();
+ ima_init_template_list();
+ hash_setup(CONFIG_IMA_DEFAULT_HASH);
+ error = ima_init();
+
+ if (error && strcmp(hash_algo_name[ima_hash_algo],
+ CONFIG_IMA_DEFAULT_HASH) != 0) {
+ pr_info("Allocating %s failed, going to use default hash algorithm %s\n",
+ hash_algo_name[ima_hash_algo], CONFIG_IMA_DEFAULT_HASH);
+ hash_setup_done = 0;
+ hash_setup(CONFIG_IMA_DEFAULT_HASH);
+ error = ima_init();
+ }
+
+ if (error)
+ return error;
+
+ error = register_blocking_lsm_notifier(&ima_lsm_policy_notifier);
+ if (error)
+ pr_warn("Couldn't register LSM notifier, error %d\n", error);
+
+ if (!error)
+ ima_update_policy_flags();
+
+ return error;
+}
+
+late_initcall(init_ima); /* Start IMA after the TPM is available */