1 files changed, 190 insertions, 0 deletions

diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
new file mode 100644
index 000000000000..a148a25804f6
--- /dev/null
+++ b/security/integrity/ima/ima_api.c
@@ -0,0 +1,190 @@
+/*
+ * Copyright (C) 2008 IBM Corporation
+ *
+ * Author: 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_api.c
+ *      Implements must_measure, collect_measurement, store_measurement,
+ *      and store_template.
+ */
+#include <linux/module.h>
+
+#include "ima.h"
+static char *IMA_TEMPLATE_NAME = "ima";
+
+/*
+ * ima_store_template - store ima template measurements
+ *
+ * Calculate the hash of a template entry, add the template entry
+ * to an ordered list of measurement entries maintained inside the kernel,
+ * and also update the aggregate integrity value (maintained inside the
+ * configured TPM PCR) over the hashes of the current list of measurement
+ * entries.
+ *
+ * Applications retrieve the current kernel-held measurement list through
+ * the securityfs entries in /sys/kernel/security/ima. The signed aggregate
+ * TPM PCR (called quote) can be retrieved using a TPM user space library
+ * and is used to validate the measurement list.
+ *
+ * Returns 0 on success, error code otherwise
+ */
+int ima_store_template(struct ima_template_entry *entry,
+                       int violation, struct inode *inode)
+{
+        const char *op = "add_template_measure";
+        const char *audit_cause = "hashing_error";
+        int result;
+
+        memset(entry->digest, 0, sizeof(entry->digest));
+        entry->template_name = IMA_TEMPLATE_NAME;
+        entry->template_len = sizeof(entry->template);
+
+        if (!violation) {
+                result = ima_calc_template_hash(entry->template_len,
+                                                &entry->template,
+                                                entry->digest);
+                if (result < 0) {
+                        integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
+                                            entry->template_name, op,
+                                            audit_cause, result, 0);
+                        return result;
+                }
+        }
+        result = ima_add_template_entry(entry, violation, op, inode);
+        return result;
+}
+
+/*
+ * ima_add_violation - add violation to measurement list.
+ *
+ * Violations are flagged in the measurement list with zero hash values.
+ * By extending the PCR with 0xFF's instead of with zeroes, the PCR
+ * value is invalidated.
+ */
+void ima_add_violation(struct inode *inode, const unsigned char *filename,
+                       const char *op, const char *cause)
+{
+        struct ima_template_entry *entry;
+        int violation = 1;
+        int result;
+
+        /* can overflow, only indicator */
+        atomic_long_inc(&ima_htable.violations);
+
+        entry = kmalloc(sizeof(*entry), GFP_KERNEL);
+        if (!entry) {
+                result = -ENOMEM;
+                goto err_out;
+        }
+        memset(&entry->template, 0, sizeof(entry->template));
+        strncpy(entry->template.file_name, filename, IMA_EVENT_NAME_LEN_MAX);
+        result = ima_store_template(entry, violation, inode);
+        if (result < 0)
+                kfree(entry);
+err_out:
+        integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
+                            op, cause, result, 0);
+}
+
+/**
+ * ima_must_measure - measure decision based on policy.
+ * @inode: pointer to inode to measure
+ * @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXECUTE)
+ * @function: calling function (PATH_CHECK, BPRM_CHECK, FILE_MMAP)
+ *
+ * The policy is defined in terms of keypairs:
+ *              subj=, obj=, type=, func=, mask=, fsmagic=
+ *      subj,obj, and type: are LSM specific.
+ *      func: PATH_CHECK | BPRM_CHECK | FILE_MMAP
+ *      mask: contains the permission mask
+ *      fsmagic: hex value
+ *
+ * Must be called with iint->mutex held.
+ *
+ * Return 0 to measure. Return 1 if already measured.
+ * For matching a DONT_MEASURE policy, no policy, or other
+ * error, return an error code.
+*/
+int ima_must_measure(struct ima_iint_cache *iint, struct inode *inode,
+                     int mask, int function)
+{
+        int must_measure;
+
+        if (iint->flags & IMA_MEASURED)
+                return 1;
+
+        must_measure = ima_match_policy(inode, function, mask);
+        return must_measure ? 0 : -EACCES;
+}
+
+/*
+ * ima_collect_measurement - collect file measurement
+ *
+ * Calculate the file hash, if it doesn't already exist,
+ * storing the measurement and i_version in the iint.
+ *
+ * Must be called with iint->mutex held.
+ *
+ * Return 0 on success, error code otherwise
+ */
+int ima_collect_measurement(struct ima_iint_cache *iint, struct file *file)
+{
+        int result = -EEXIST;
+
+        if (!(iint->flags & IMA_MEASURED)) {
+                u64 i_version = file->f_dentry->d_inode->i_version;
+
+                memset(iint->digest, 0, IMA_DIGEST_SIZE);
+                result = ima_calc_hash(file, iint->digest);
+                if (!result)
+                        iint->version = i_version;
+        }
+        return result;
+}
+
+/*
+ * ima_store_measurement - store file measurement
+ *
+ * Create an "ima" template and then store the template by calling
+ * ima_store_template.
+ *
+ * We only get here if the inode has not already been measured,
+ * but the measurement could already exist:
+ *      - multiple copies of the same file on either the same or
+ *        different filesystems.
+ *      - the inode was previously flushed as well as the iint info,
+ *        containing the hashing info.
+ *
+ * Must be called with iint->mutex held.
+ */
+void ima_store_measurement(struct ima_iint_cache *iint, struct file *file,
+                           const unsigned char *filename)
+{
+        const char *op = "add_template_measure";
+        const char *audit_cause = "ENOMEM";
+        int result = -ENOMEM;
+        struct inode *inode = file->f_dentry->d_inode;
+        struct ima_template_entry *entry;
+        int violation = 0;
+
+        entry = kmalloc(sizeof(*entry), GFP_KERNEL);
+        if (!entry) {
+                integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
+                                    op, audit_cause, result, 0);
+                return;
+        }
+        memset(&entry->template, 0, sizeof(entry->template));
+        memcpy(entry->template.digest, iint->digest, IMA_DIGEST_SIZE);
+        strncpy(entry->template.file_name, filename, IMA_EVENT_NAME_LEN_MAX);
+
+        result = ima_store_template(entry, violation, inode);
+        if (!result)
+                iint->flags |= IMA_MEASURED;
+        else
+                kfree(entry);
+}