// SPDX-License-Identifier: GPL-2.0-or-later
/* procfs files for key database enumeration
 *
 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#include <linux/init.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <asm/errno.h>
#include "internal.h"

static void *proc_keys_start(struct seq_file *p, loff_t *_pos);
static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos);
static void proc_keys_stop(struct seq_file *p, void *v);
static int proc_keys_show(struct seq_file *m, void *v);

static const struct seq_operations proc_keys_ops = {
        .start  = proc_keys_start,
        .next   = proc_keys_next,
        .stop   = proc_keys_stop,
        .show   = proc_keys_show,
};

static void *proc_key_users_start(struct seq_file *p, loff_t *_pos);
static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos);
static void proc_key_users_stop(struct seq_file *p, void *v);
static int proc_key_users_show(struct seq_file *m, void *v);

static const struct seq_operations proc_key_users_ops = {
        .start  = proc_key_users_start,
        .next   = proc_key_users_next,
        .stop   = proc_key_users_stop,
        .show   = proc_key_users_show,
};

/*
 * Declare the /proc files.
 */
static int __init key_proc_init(void)
{
        struct proc_dir_entry *p;

        p = proc_create_seq("keys", 0, NULL, &proc_keys_ops);
        if (!p)
                panic("Cannot create /proc/keys\n");

        p = proc_create_seq("key-users", 0, NULL, &proc_key_users_ops);
        if (!p)
                panic("Cannot create /proc/key-users\n");

        return 0;
}

__initcall(key_proc_init);

/*
 * Implement "/proc/keys" to provide a list of the keys on the system that
 * grant View permission to the caller.
 */
static struct rb_node *key_serial_next(struct seq_file *p, struct rb_node *n)
{
        struct user_namespace *user_ns = seq_user_ns(p);

        n = rb_next(n);
        while (n) {
                struct key *key = rb_entry(n, struct key, serial_node);
                if (kuid_has_mapping(user_ns, key->user->uid))
                        break;
                n = rb_next(n);
        }
        return n;
}

static struct key *find_ge_key(struct seq_file *p, key_serial_t id)
{
        struct user_namespace *user_ns = seq_user_ns(p);
        struct rb_node *n = key_serial_tree.rb_node;
        struct key *minkey = NULL;

        while (n) {
                struct key *key = rb_entry(n, struct key, serial_node);
                if (id < key->serial) {
                        if (!minkey || minkey->serial > key->serial)
                                minkey = key;
                        n = n->rb_left;
                } else if (id > key->serial) {
                        n = n->rb_right;
                } else {
                        minkey = key;
                        break;
                }
                key = NULL;
        }

        if (!minkey)
                return NULL;

        for (;;) {
                if (kuid_has_mapping(user_ns, minkey->user->uid))
                        return minkey;
                n = rb_next(&minkey->serial_node);
                if (!n)
                        return NULL;
                minkey = rb_entry(n, struct key, serial_node);
        }
}

static void *proc_keys_start(struct seq_file *p, loff_t *_pos)
        __acquires(key_serial_lock)
{
        key_serial_t pos = *_pos;
        struct key *key;

        spin_lock(&key_serial_lock);

        if (*_pos > INT_MAX)
                return NULL;
        key = find_ge_key(p, pos);
        if (!key)
                return NULL;
        *_pos = key->serial;
        return &key->serial_node;
}

static inline key_serial_t key_node_serial(struct rb_node *n)
{
        struct key *key = rb_entry(n, struct key, serial_node);
        return key->serial;
}

static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos)
{
        struct rb_node *n;

        n = key_serial_next(p, v);
        if (n)
                *_pos = key_node_serial(n);
        else
                (*_pos)++;
        return n;
}

static void proc_keys_stop(struct seq_file *p, void *v)
        __releases(key_serial_lock)
{
        spin_unlock(&key_serial_lock);
}

static int proc_keys_show(struct seq_file *m, void *v)
{
        struct rb_node *_p = v;
        struct key *key = rb_entry(_p, struct key, serial_node);
        unsigned long flags;
        key_ref_t key_ref, skey_ref;
        time64_t now, expiry;
        char xbuf[16];
        short state;
        u64 timo;
        int rc;

        struct keyring_search_context ctx = {
                .index_key              = key->index_key,
                .cred                   = m->file->f_cred,
                .match_data.cmp         = lookup_user_key_possessed,
                .match_data.raw_data    = key,
                .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
                .flags                  = (KEYRING_SEARCH_NO_STATE_CHECK |
                                           KEYRING_SEARCH_RECURSE),
        };

        key_ref = make_key_ref(key, 0);

        /* determine if the key is possessed by this process (a test we can
         * skip if the key does not indicate the possessor can view it
         */
        if (key->perm & KEY_POS_VIEW) {
                rcu_read_lock();
                skey_ref = search_cred_keyrings_rcu(&ctx);
                rcu_read_unlock();
                if (!IS_ERR(skey_ref)) {
                        key_ref_put(skey_ref);
                        key_ref = make_key_ref(key, 1);
                }
        }

        /* check whether the current task is allowed to view the key */
        rc = key_task_permission(key_ref, ctx.cred, KEY_NEED_VIEW);
        if (rc < 0)
                return 0;

        now = ktime_get_real_seconds();

        rcu_read_lock();

        /* come up with a suitable timeout value */
        expiry = READ_ONCE(key->expiry);
        if (expiry == TIME64_MAX) {
                memcpy(xbuf, "perm", 5);
        } else if (now >= expiry) {
                memcpy(xbuf, "expd", 5);
        } else {
                timo = expiry - now;

                if (timo < 60)
                        sprintf(xbuf, "%llus", timo);
                else if (timo < 60*60)
                        sprintf(xbuf, "%llum", div_u64(timo, 60));
                else if (timo < 60*60*24)
                        sprintf(xbuf, "%lluh", div_u64(timo, 60 * 60));
                else if (timo < 60*60*24*7)
                        sprintf(xbuf, "%llud", div_u64(timo, 60 * 60 * 24));
                else
                        sprintf(xbuf, "%lluw", div_u64(timo, 60 * 60 * 24 * 7));
        }

        state = key_read_state(key);

#define showflag(FLAGS, LETTER, FLAG) \
        ((FLAGS & (1 << FLAG)) ? LETTER : '-')

        flags = READ_ONCE(key->flags);
        seq_printf(m, "%08x %c%c%c%c%c%c%c %5d %4s %08x %5d %5d %-9.9s ",
                   key->serial,
                   state != KEY_IS_UNINSTANTIATED ? 'I' : '-',
                   showflag(flags, 'R', KEY_FLAG_REVOKED),
                   showflag(flags, 'D', KEY_FLAG_DEAD),
                   showflag(flags, 'Q', KEY_FLAG_IN_QUOTA),
                   showflag(flags, 'U', KEY_FLAG_USER_CONSTRUCT),
                   state < 0 ? 'N' : '-',
                   showflag(flags, 'i', KEY_FLAG_INVALIDATED),
                   refcount_read(&key->usage),
                   xbuf,
                   key->perm,
                   from_kuid_munged(seq_user_ns(m), key->uid),
                   from_kgid_munged(seq_user_ns(m), key->gid),
                   key->type->name);

#undef showflag

        if (key->type->describe)
                key->type->describe(key, m);
        seq_putc(m, '\n');

        rcu_read_unlock();
        return 0;
}

static struct rb_node *__key_user_next(struct user_namespace *user_ns, struct rb_node *n)
{
        while (n) {
                struct key_user *user = rb_entry(n, struct key_user, node);
                if (kuid_has_mapping(user_ns, user->uid))
                        break;
                n = rb_next(n);
        }
        return n;
}

static struct rb_node *key_user_next(struct user_namespace *user_ns, struct rb_node *n)
{
        return __key_user_next(user_ns, rb_next(n));
}

static struct rb_node *key_user_first(struct user_namespace *user_ns, struct rb_root *r)
{
        struct rb_node *n = rb_first(r);
        return __key_user_next(user_ns, n);
}

static void *proc_key_users_start(struct seq_file *p, loff_t *_pos)
        __acquires(key_user_lock)
{
        struct rb_node *_p;
        loff_t pos = *_pos;

        spin_lock(&key_user_lock);

        _p = key_user_first(seq_user_ns(p), &key_user_tree);
        while (pos > 0 && _p) {
                pos--;
                _p = key_user_next(seq_user_ns(p), _p);
        }

        return _p;
}

static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos)
{
        (*_pos)++;
        return key_user_next(seq_user_ns(p), (struct rb_node *)v);
}

static void proc_key_users_stop(struct seq_file *p, void *v)
        __releases(key_user_lock)
{
        spin_unlock(&key_user_lock);
}

static int proc_key_users_show(struct seq_file *m, void *v)
{
        struct rb_node *_p = v;
        struct key_user *user = rb_entry(_p, struct key_user, node);
        unsigned maxkeys = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
                key_quota_root_maxkeys : key_quota_maxkeys;
        unsigned maxbytes = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
                key_quota_root_maxbytes : key_quota_maxbytes;

        seq_printf(m, "%5u: %5d %d/%d %d/%d %d/%d\n",
                   from_kuid_munged(seq_user_ns(m), user->uid),
                   refcount_read(&user->usage),
                   atomic_read(&user->nkeys),
                   atomic_read(&user->nikeys),
                   user->qnkeys,
                   maxkeys,
                   user->qnbytes,
                   maxbytes);

        return 0;
}