// 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

bool ima_flush_htable;

static int __init ima_flush_htable_setup(char *str)
{
        if (IS_ENABLED(CONFIG_IMA_DISABLE_HTABLE)) {
                pr_warn("Hash table not enabled, ignoring request to flush\n");
                return 1;
        }

        ima_flush_htable = true;
        return 1;
}
__setup("ima_flush_htable", ima_flush_htable_setup);

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

LIST_HEAD(ima_measurements);    /* list of all measurements */
LIST_HEAD(ima_measurements_staged); /* list of staged measurements */
#ifdef CONFIG_IMA_KEXEC
static unsigned long binary_runtime_size[BINARY__LAST];
#else
static unsigned long binary_runtime_size[BINARY__LAST] = {
        [0 ... BINARY__LAST - 1] = ULONG_MAX
};
#endif

atomic_long_t ima_num_records[BINARY__LAST] = {
        [0 ... BINARY__LAST - 1] = ATOMIC_LONG_INIT(0)
};
atomic_long_t ima_num_violations = ATOMIC_LONG_INIT(0);

/* key: inode (before secure-hashing a file) */
struct hlist_head __rcu *ima_htable;

/* mutex protects atomicity of extending and staging 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;

/* Callers must call synchronize_rcu() and free the hash table. */
static struct hlist_head *ima_alloc_replace_htable(void)
{
        struct hlist_head *old_htable, *new_htable;

        /* Initializing to zeros is equivalent to call HLIST_HEAD_INIT. */
        new_htable = kcalloc(IMA_MEASURE_HTABLE_SIZE, sizeof(struct hlist_head),
                             GFP_KERNEL);
        if (!new_htable)
                return ERR_PTR(-ENOMEM);

        old_htable = rcu_replace_pointer(ima_htable, new_htable,
                                lockdep_is_held(&ima_extend_list_mutex));

        return old_htable;
}

int __init ima_init_htable(void)
{
        struct hlist_head *old_htable;

        mutex_lock(&ima_extend_list_mutex);
        old_htable = ima_alloc_replace_htable();
        mutex_unlock(&ima_extend_list_mutex);

        if (IS_ERR(old_htable))
                return PTR_ERR(old_htable);

        /* Synchronize_rcu() and kfree() not necessary, only for robustness. */
        synchronize_rcu();
        kfree(old_htable);
        return 0;
}

/* 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;
        struct hlist_head *htable;
        unsigned int key;
        int rc;

        key = ima_hash_key(digest_value);
        rcu_read_lock();
        htable = rcu_dereference(ima_htable);
        hlist_for_each_entry_rcu(qe, &htable[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;
}

static void ima_update_binary_runtime_size(struct ima_template_entry *entry,
                                           enum binary_lists binary_list)
{
        int size;

        if (binary_runtime_size[binary_list] == ULONG_MAX)
                return;

        size = get_binary_runtime_size(entry);
        binary_runtime_size[binary_list] =
                (binary_runtime_size[binary_list] < ULONG_MAX - size) ?
                binary_runtime_size[binary_list] + size : ULONG_MAX;
}

/* 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;
        struct hlist_head *htable;
        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);

        htable = rcu_dereference_protected(ima_htable,
                                lockdep_is_held(&ima_extend_list_mutex));

        atomic_long_inc(&ima_num_records[BINARY]);
        atomic_long_inc(&ima_num_records[BINARY_FULL]);

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

        ima_update_binary_runtime_size(entry, BINARY);
        ima_update_binary_runtime_size(entry, BINARY_FULL);

        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(enum binary_lists binary_list)
{
        unsigned long val;

        mutex_lock(&ima_extend_list_mutex);
        val = binary_runtime_size[binary_list];
        mutex_unlock(&ima_extend_list_mutex);

        if (val >= (ULONG_MAX - sizeof(struct ima_kexec_hdr)))
                return ULONG_MAX;
        else
                return val + 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;
}

/**
 * ima_queue_stage - Stage all measurements
 *
 * If the staged measurements list is empty, the current measurements list is
 * not empty, and measurement is not suspended, move the measurements from the
 * current list to the staged one, and update the number of records and binary
 * run-time size accordingly.
 *
 * Do not allow staging after measurement is suspended, so that dumping
 * measurements can be done in a lockless way.
 *
 * Return: Zero on success, a negative value otherwise.
 */
int ima_queue_stage(void)
{
        int ret = 0;

        mutex_lock(&ima_extend_list_mutex);
        if (!list_empty(&ima_measurements_staged)) {
                ret = -EEXIST;
                goto out_unlock;
        }

        if (list_empty(&ima_measurements)) {
                ret = -ENOENT;
                goto out_unlock;
        }

        if (ima_measurements_suspended) {
                ret = -EACCES;
                goto out_unlock;
        }

        list_replace(&ima_measurements, &ima_measurements_staged);
        INIT_LIST_HEAD(&ima_measurements);

        atomic_long_set(&ima_num_records[BINARY_STAGED],
                        atomic_long_read(&ima_num_records[BINARY]));
        atomic_long_set(&ima_num_records[BINARY], 0);

        if (IS_ENABLED(CONFIG_IMA_KEXEC)) {
                binary_runtime_size[BINARY_STAGED] =
                                        binary_runtime_size[BINARY];
                binary_runtime_size[BINARY] = 0;
        }
out_unlock:
        mutex_unlock(&ima_extend_list_mutex);
        return ret;
}

static void ima_queue_delete(struct list_head *head, bool flush_htable);

/**
 * ima_queue_staged_delete_all - Delete staged measurements
 *
 * Move staged measurements to a temporary list, ima_measurements_trim, update
 * the number of records and the binary run-time size accordingly. Finally,
 * delete measurements in the temporary list.
 *
 * Refuse to delete staged measurements if measurement is suspended, so that
 * dump can be done in a lockless way and user space is notified about staged
 * measurements being carried over to the secondary kernel, so that it does not
 * save them twice.
 *
 * Return: Zero on success, a negative value otherwise.
 */
int ima_queue_staged_delete_all(void)
{
        struct hlist_head *old_queue = NULL;
        LIST_HEAD(ima_measurements_trim);

        mutex_lock(&ima_extend_list_mutex);
        if (list_empty(&ima_measurements_staged)) {
                mutex_unlock(&ima_extend_list_mutex);
                return -ENOENT;
        }

        if (ima_measurements_suspended) {
                mutex_unlock(&ima_extend_list_mutex);
                return -ESTALE;
        }

        list_replace(&ima_measurements_staged, &ima_measurements_trim);
        INIT_LIST_HEAD(&ima_measurements_staged);

        atomic_long_set(&ima_num_records[BINARY_STAGED], 0);

        if (IS_ENABLED(CONFIG_IMA_KEXEC))
                binary_runtime_size[BINARY_STAGED] = 0;

        if (ima_flush_htable) {
                old_queue = ima_alloc_replace_htable();
                if (IS_ERR(old_queue)) {
                        mutex_unlock(&ima_extend_list_mutex);
                        return PTR_ERR(old_queue);
                }
        }

        mutex_unlock(&ima_extend_list_mutex);

        if (ima_flush_htable) {
                synchronize_rcu();
                kfree(old_queue);
        }

        ima_queue_delete(&ima_measurements_trim, ima_flush_htable);
        return 0;
}

/**
 * ima_queue_delete_partial - Delete current measurements
 * @req_value: Number of measurements to delete
 *
 * Delete the requested number of measurements from the current measurements
 * list, and update the number of records and the binary run-time size
 * accordingly.
 *
 * Refuse to delete current measurements if measurement is suspended, so that
 * dump can be done in a lockless way and user space is notified about current
 * measurements being carried over to the secondary kernel, so that it does not
 * save them twice.
 *
 * Return: Zero on success, a negative value otherwise.
 */
int ima_queue_delete_partial(unsigned long req_value)
{
        unsigned long req_value_copy = req_value;
        unsigned long size_to_remove = 0, num_to_remove = 0;
        LIST_HEAD(ima_measurements_trim);
        struct ima_queue_entry *qe;
        int ret = 0;

        /*
         * list_for_each_entry_rcu() without rcu_read_lock() is fine because
         * only list append can happen concurrently. No list replace due to the
         * staging/delete writers mutual exclusion.
         */
        list_for_each_entry_rcu(qe, &ima_measurements, later, true) {
                size_to_remove += get_binary_runtime_size(qe->entry);
                num_to_remove++;

                if (--req_value_copy == 0)
                        break;
        }

        /* Not enough records to delete. */
        if (req_value_copy > 0)
                return -ENOENT;

        mutex_lock(&ima_extend_list_mutex);
        if (ima_measurements_suspended) {
                mutex_unlock(&ima_extend_list_mutex);
                return -ESTALE;
        }

        /*
         * qe remains valid because ima_fs.c enforces single-writer exclusion.
         */
        __list_cut_position(&ima_measurements_trim, &ima_measurements,
                            &qe->later);

        atomic_long_sub(num_to_remove, &ima_num_records[BINARY]);

        if (IS_ENABLED(CONFIG_IMA_KEXEC))
                binary_runtime_size[BINARY] -= size_to_remove;

        mutex_unlock(&ima_extend_list_mutex);

        ima_queue_delete(&ima_measurements_trim, false);
        return ret;
}

/**
 * ima_queue_delete - Delete measurements
 * @head: List head measurements are deleted from
 * @flush_htable: Whether or not the hash table is being flushed
 *
 * Delete the measurements from the passed list head completely if the
 * hash table is not enabled or is being flushed, or partially (only the
 * template data), if the hash table is used.
 */
static void ima_queue_delete(struct list_head *head, bool flush_htable)
{
        struct ima_queue_entry *qe, *qe_tmp;
        unsigned int i;

        list_for_each_entry_safe(qe, qe_tmp, head, later) {
                /*
                 * Safe to free template_data here without synchronize_rcu()
                 * because the only htable reader, ima_lookup_digest_entry(),
                 * accesses only entry->digests, not template_data. If new
                 * htable readers are added that access template_data, a
                 * synchronize_rcu() is required here.
                 */
                for (i = 0; i < qe->entry->template_desc->num_fields; i++) {
                        kfree(qe->entry->template_data[i].data);
                        qe->entry->template_data[i].data = NULL;
                        qe->entry->template_data[i].len = 0;
                }

                list_del(&qe->later);

                /* No leak if condition is false, referenced by ima_htable. */
                if (IS_ENABLED(CONFIG_IMA_DISABLE_HTABLE) || flush_htable) {
                        kfree(qe->entry->digests);
                        kfree(qe->entry);
                        kfree(qe);
                }
        }
}

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;
}