// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2005,2006,2007,2008 IBM Corporation
 *
 * Authors:
 * Serge Hallyn <serue@us.ibm.com>
 * Reiner Sailer <sailer@watson.ibm.com>
 * Mimi Zohar <zohar@us.ibm.com>
 *
 * File: ima_queue.c
 *       Implements queues that store template measurements and
 *       maintains aggregate over the stored measurements
 *       in the pre-configured TPM PCR (if available).
 *       The measurement list is append-only. No entry is
 *       ever removed or changed during the boot-cycle.
 */

#include <linux/rculist.h>
#include <linux/reboot.h>
#include <linux/slab.h>
#include "ima.h"

#define AUDIT_CAUSE_LEN_MAX 32

/* pre-allocated array of tpm_digest structures to extend a PCR */
static struct tpm_digest *digests;

LIST_HEAD(ima_measurements);    /* list of all measurements */
#ifdef CONFIG_IMA_KEXEC
static unsigned long binary_runtime_size;
#else
static unsigned long binary_runtime_size = ULONG_MAX;
#endif

/* key: inode (before secure-hashing a file) */
struct ima_h_table ima_htable = {
        .len = ATOMIC_LONG_INIT(0),
        .violations = ATOMIC_LONG_INIT(0),
        .queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT
};

/* mutex protects atomicity of extending measurement list
 * and extending the TPM PCR aggregate. Since tpm_extend can take
 * long (and the tpm driver uses a mutex), we can't use the spinlock.
 */
static DEFINE_MUTEX(ima_extend_list_mutex);

/*
 * Used internally by the kernel to suspend measurements.
 * Protected by ima_extend_list_mutex.
 */
static bool ima_measurements_suspended;

/* lookup up the digest value in the hash table, and return the entry */
static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value,
                                                       int pcr)
{
        struct ima_queue_entry *qe, *ret = NULL;
        unsigned int key;
        int rc;

        key = ima_hash_key(digest_value);
        rcu_read_lock();
        hlist_for_each_entry_rcu(qe, &ima_htable.queue[key], hnext) {
                rc = memcmp(qe->entry->digests[ima_hash_algo_idx].digest,
                            digest_value, hash_digest_size[ima_hash_algo]);
                if ((rc == 0) && (qe->entry->pcr == pcr)) {
                        ret = qe;
                        break;
                }
        }
        rcu_read_unlock();
        return ret;
}

/*
 * Calculate the memory required for serializing a single
 * binary_runtime_measurement list entry, which contains a
 * couple of variable length fields (e.g template name and data).
 */
static int get_binary_runtime_size(struct ima_template_entry *entry)
{
        int size = 0;

        size += sizeof(u32);    /* pcr */
        size += TPM_DIGEST_SIZE;
        size += sizeof(int);    /* template name size field */
        size += strlen(entry->template_desc->name);
        size += sizeof(entry->template_data_len);
        size += entry->template_data_len;
        return size;
}

/* ima_add_template_entry helper function:
 * - Add template entry to the measurement list and hash table, for
 *   all entries except those carried across kexec.
 *
 * (Called with ima_extend_list_mutex held.)
 */
static int ima_add_digest_entry(struct ima_template_entry *entry,
                                bool update_htable)
{
        struct ima_queue_entry *qe;
        unsigned int key;

        qe = kmalloc_obj(*qe);
        if (qe == NULL) {
                pr_err("OUT OF MEMORY ERROR creating queue entry\n");
                return -ENOMEM;
        }
        qe->entry = entry;

        INIT_LIST_HEAD(&qe->later);
        list_add_tail_rcu(&qe->later, &ima_measurements);

        atomic_long_inc(&ima_htable.len);
        if (update_htable) {
                key = ima_hash_key(entry->digests[ima_hash_algo_idx].digest);
                hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]);
        }

        if (binary_runtime_size != ULONG_MAX) {
                int size;

                size = get_binary_runtime_size(entry);
                binary_runtime_size = (binary_runtime_size < ULONG_MAX - size) ?
                     binary_runtime_size + size : ULONG_MAX;
        }
        return 0;
}

/*
 * Return the amount of memory required for serializing the
 * entire binary_runtime_measurement list, including the ima_kexec_hdr
 * structure.
 */
unsigned long ima_get_binary_runtime_size(void)
{
        if (binary_runtime_size >= (ULONG_MAX - sizeof(struct ima_kexec_hdr)))
                return ULONG_MAX;
        else
                return binary_runtime_size + sizeof(struct ima_kexec_hdr);
}

static int ima_pcr_extend(struct tpm_digest *digests_arg, int pcr)
{
        int result = 0;

        if (!ima_tpm_chip)
                return result;

        result = tpm_pcr_extend(ima_tpm_chip, pcr, digests_arg);
        if (result != 0)
                pr_err("Error Communicating to TPM chip, result: %d\n", result);
        return result;
}

/*
 * Add template entry to the measurement list and hash table, and
 * extend the pcr.
 *
 * On systems which support carrying the IMA measurement list across
 * kexec, maintain the total memory size required for serializing the
 * binary_runtime_measurements.
 */
int ima_add_template_entry(struct ima_template_entry *entry, int violation,
                           const char *op, struct inode *inode,
                           const unsigned char *filename)
{
        u8 *digest = entry->digests[ima_hash_algo_idx].digest;
        struct tpm_digest *digests_arg = entry->digests;
        const char *audit_cause = "hash_added";
        char tpm_audit_cause[AUDIT_CAUSE_LEN_MAX];
        int audit_info = 1;
        int result = 0, tpmresult = 0;

        mutex_lock(&ima_extend_list_mutex);

        /*
         * Avoid appending to the measurement log when the TPM subsystem has
         * been shut down while preparing for system reboot.
         */
        if (ima_measurements_suspended) {
                audit_cause = "measurements_suspended";
                audit_info = 0;
                result = -ENODEV;
                goto out;
        }

        if (!violation && !IS_ENABLED(CONFIG_IMA_DISABLE_HTABLE)) {
                if (ima_lookup_digest_entry(digest, entry->pcr)) {
                        audit_cause = "hash_exists";
                        result = -EEXIST;
                        goto out;
                }
        }

        result = ima_add_digest_entry(entry,
                                      !IS_ENABLED(CONFIG_IMA_DISABLE_HTABLE));
        if (result < 0) {
                audit_cause = "ENOMEM";
                audit_info = 0;
                goto out;
        }

        if (violation)          /* invalidate pcr */
                digests_arg = digests;

        tpmresult = ima_pcr_extend(digests_arg, entry->pcr);
        if (tpmresult != 0) {
                snprintf(tpm_audit_cause, AUDIT_CAUSE_LEN_MAX, "TPM_error(%d)",
                         tpmresult);
                audit_cause = tpm_audit_cause;
                audit_info = 0;
        }
out:
        mutex_unlock(&ima_extend_list_mutex);
        integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename,
                            op, audit_cause, result, audit_info);
        return result;
}

int ima_restore_measurement_entry(struct ima_template_entry *entry)
{
        int result = 0;

        mutex_lock(&ima_extend_list_mutex);
        result = ima_add_digest_entry(entry, 0);
        mutex_unlock(&ima_extend_list_mutex);
        return result;
}

static void ima_measurements_suspend(void)
{
        mutex_lock(&ima_extend_list_mutex);
        ima_measurements_suspended = true;
        mutex_unlock(&ima_extend_list_mutex);
}

static int ima_reboot_notifier(struct notifier_block *nb,
                               unsigned long action,
                               void *data)
{
#ifdef CONFIG_IMA_KEXEC
        if (action == SYS_RESTART && data && !strcmp(data, "kexec reboot"))
                ima_measure_kexec_event("kexec_execute");
#endif

        ima_measurements_suspend();

        return NOTIFY_DONE;
}

static struct notifier_block ima_reboot_nb = {
        .notifier_call = ima_reboot_notifier,
};

void __init ima_init_reboot_notifier(void)
{
        register_reboot_notifier(&ima_reboot_nb);
}

int __init ima_init_digests(void)
{
        u16 digest_size;
        u16 crypto_id;
        int i;

        if (!ima_tpm_chip)
                return 0;

        digests = kzalloc_objs(*digests, ima_tpm_chip->nr_allocated_banks,
                               GFP_NOFS);
        if (!digests)
                return -ENOMEM;

        for (i = 0; i < ima_tpm_chip->nr_allocated_banks; i++) {
                digests[i].alg_id = ima_tpm_chip->allocated_banks[i].alg_id;
                digest_size = ima_tpm_chip->allocated_banks[i].digest_size;
                crypto_id = ima_tpm_chip->allocated_banks[i].crypto_id;

                /* for unmapped TPM algorithms digest is still a padded SHA1 */
                if (crypto_id == HASH_ALGO__LAST)
                        digest_size = SHA1_DIGEST_SIZE;

                memset(digests[i].digest, 0xff, digest_size);
        }

        return 0;
}