cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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cache_lib.c (3936B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * linux/fs/nfs/cache_lib.c
      4 *
      5 * Helper routines for the NFS client caches
      6 *
      7 * Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com>
      8 */
      9#include <linux/kmod.h>
     10#include <linux/module.h>
     11#include <linux/moduleparam.h>
     12#include <linux/mount.h>
     13#include <linux/namei.h>
     14#include <linux/slab.h>
     15#include <linux/sunrpc/cache.h>
     16#include <linux/sunrpc/rpc_pipe_fs.h>
     17#include <net/net_namespace.h>
     18
     19#include "cache_lib.h"
     20
     21#define NFS_CACHE_UPCALL_PATHLEN 256
     22#define NFS_CACHE_UPCALL_TIMEOUT 15
     23
     24static char nfs_cache_getent_prog[NFS_CACHE_UPCALL_PATHLEN] =
     25				"/sbin/nfs_cache_getent";
     26static unsigned long nfs_cache_getent_timeout = NFS_CACHE_UPCALL_TIMEOUT;
     27
     28module_param_string(cache_getent, nfs_cache_getent_prog,
     29		sizeof(nfs_cache_getent_prog), 0600);
     30MODULE_PARM_DESC(cache_getent, "Path to the client cache upcall program");
     31module_param_named(cache_getent_timeout, nfs_cache_getent_timeout, ulong, 0600);
     32MODULE_PARM_DESC(cache_getent_timeout, "Timeout (in seconds) after which "
     33		"the cache upcall is assumed to have failed");
     34
     35int nfs_cache_upcall(struct cache_detail *cd, char *entry_name)
     36{
     37	static char *envp[] = { "HOME=/",
     38		"TERM=linux",
     39		"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
     40		NULL
     41	};
     42	char *argv[] = {
     43		nfs_cache_getent_prog,
     44		cd->name,
     45		entry_name,
     46		NULL
     47	};
     48	int ret = -EACCES;
     49
     50	if (nfs_cache_getent_prog[0] == '\0')
     51		goto out;
     52	ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
     53	/*
     54	 * Disable the upcall mechanism if we're getting an ENOENT or
     55	 * EACCES error. The admin can re-enable it on the fly by using
     56	 * sysfs to set the 'cache_getent' parameter once the problem
     57	 * has been fixed.
     58	 */
     59	if (ret == -ENOENT || ret == -EACCES)
     60		nfs_cache_getent_prog[0] = '\0';
     61out:
     62	return ret > 0 ? 0 : ret;
     63}
     64
     65/*
     66 * Deferred request handling
     67 */
     68void nfs_cache_defer_req_put(struct nfs_cache_defer_req *dreq)
     69{
     70	if (refcount_dec_and_test(&dreq->count))
     71		kfree(dreq);
     72}
     73
     74static void nfs_dns_cache_revisit(struct cache_deferred_req *d, int toomany)
     75{
     76	struct nfs_cache_defer_req *dreq;
     77
     78	dreq = container_of(d, struct nfs_cache_defer_req, deferred_req);
     79
     80	complete(&dreq->completion);
     81	nfs_cache_defer_req_put(dreq);
     82}
     83
     84static struct cache_deferred_req *nfs_dns_cache_defer(struct cache_req *req)
     85{
     86	struct nfs_cache_defer_req *dreq;
     87
     88	dreq = container_of(req, struct nfs_cache_defer_req, req);
     89	dreq->deferred_req.revisit = nfs_dns_cache_revisit;
     90	refcount_inc(&dreq->count);
     91
     92	return &dreq->deferred_req;
     93}
     94
     95struct nfs_cache_defer_req *nfs_cache_defer_req_alloc(void)
     96{
     97	struct nfs_cache_defer_req *dreq;
     98
     99	dreq = kzalloc(sizeof(*dreq), GFP_KERNEL);
    100	if (dreq) {
    101		init_completion(&dreq->completion);
    102		refcount_set(&dreq->count, 1);
    103		dreq->req.defer = nfs_dns_cache_defer;
    104	}
    105	return dreq;
    106}
    107
    108int nfs_cache_wait_for_upcall(struct nfs_cache_defer_req *dreq)
    109{
    110	if (wait_for_completion_timeout(&dreq->completion,
    111			nfs_cache_getent_timeout * HZ) == 0)
    112		return -ETIMEDOUT;
    113	return 0;
    114}
    115
    116int nfs_cache_register_sb(struct super_block *sb, struct cache_detail *cd)
    117{
    118	int ret;
    119	struct dentry *dir;
    120
    121	dir = rpc_d_lookup_sb(sb, "cache");
    122	ret = sunrpc_cache_register_pipefs(dir, cd->name, 0600, cd);
    123	dput(dir);
    124	return ret;
    125}
    126
    127int nfs_cache_register_net(struct net *net, struct cache_detail *cd)
    128{
    129	struct super_block *pipefs_sb;
    130	int ret = 0;
    131
    132	sunrpc_init_cache_detail(cd);
    133	pipefs_sb = rpc_get_sb_net(net);
    134	if (pipefs_sb) {
    135		ret = nfs_cache_register_sb(pipefs_sb, cd);
    136		rpc_put_sb_net(net);
    137		if (ret)
    138			sunrpc_destroy_cache_detail(cd);
    139	}
    140	return ret;
    141}
    142
    143void nfs_cache_unregister_sb(struct super_block *sb, struct cache_detail *cd)
    144{
    145	sunrpc_cache_unregister_pipefs(cd);
    146}
    147
    148void nfs_cache_unregister_net(struct net *net, struct cache_detail *cd)
    149{
    150	struct super_block *pipefs_sb;
    151
    152	pipefs_sb = rpc_get_sb_net(net);
    153	if (pipefs_sb) {
    154		nfs_cache_unregister_sb(pipefs_sb, cd);
    155		rpc_put_sb_net(net);
    156	}
    157	sunrpc_destroy_cache_detail(cd);
    158}