Commit 6238aec8 authored by NeilBrown's avatar NeilBrown Committed by Anna Schumaker
Browse files

NFS: don't store 'struct cred *' in struct nfs_access_entry 



Storing the 'struct cred *' in nfs_access_entry is problematic.
An active 'cred' can keep a 'struct key *' active, and a quota is
imposed on the number of such keys that a user can maintain.
Cached 'nfs_access_entry' structs have indefinite lifetime, and having
these keep 'struct key's alive imposes on that quota.

So remove the 'struct cred *' and replace it with the fields we need:
  kuid_t, kgid_t, and struct group_info *

This makes the 'struct nfs_access_entry' 64 bits larger.

New function "access_cmp" is introduced which is identical to
cred_fscmp() except that the second arg is an 'nfs_access_entry', rather
than a 'cred'

Fixes: b68572e0 ("NFS: change access cache to use 'struct cred'.")
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent 73fbb3fa

fs/nfs/dir.c

+44 −6
Original line number Diff line number Diff line
@@ -2528,7 +2528,7 @@ MODULE_PARM_DESC(nfs_access_max_cachesize, "NFS access maximum total cache lengt 


static void nfs_access_free_entry(struct nfs_access_entry *entry)

{

	put_cred(entry->cred);

	put_group_info(entry->group_info);

	kfree_rcu(entry, rcu_head);

	smp_mb__before_atomic();

	atomic_long_dec(&nfs_access_nr_entries);
@@ -2654,6 +2654,43 @@ void nfs_access_zap_cache(struct inode *inode) 
}

EXPORT_SYMBOL_GPL(nfs_access_zap_cache);



static int access_cmp(const struct cred *a, const struct nfs_access_entry *b)

{

	struct group_info *ga, *gb;

	int g;



	if (uid_lt(a->fsuid, b->fsuid))

		return -1;

	if (uid_gt(a->fsuid, b->fsuid))

		return 1;



	if (gid_lt(a->fsgid, b->fsgid))

		return -1;

	if (gid_gt(a->fsgid, b->fsgid))

		return 1;



	ga = a->group_info;

	gb = b->group_info;

	if (ga == gb)

		return 0;

	if (ga == NULL)

		return -1;

	if (gb == NULL)

		return 1;

	if (ga->ngroups < gb->ngroups)

		return -1;

	if (ga->ngroups > gb->ngroups)

		return 1;



	for (g = 0; g < ga->ngroups; g++) {

		if (gid_lt(ga->gid[g], gb->gid[g]))

			return -1;

		if (gid_gt(ga->gid[g], gb->gid[g]))

			return 1;

	}

	return 0;

}



static struct nfs_access_entry *nfs_access_search_rbtree(struct inode *inode, const struct cred *cred)

{

	struct rb_node *n = NFS_I(inode)->access_cache.rb_node;
@@ -2661,7 +2698,7 @@ static struct nfs_access_entry *nfs_access_search_rbtree(struct inode *inode, co 
	while (n != NULL) {

		struct nfs_access_entry *entry =

			rb_entry(n, struct nfs_access_entry, rb_node);

		int cmp = cred_fscmp(cred, entry->cred);

		int cmp = access_cmp(cred, entry);



		if (cmp < 0)

			n = n->rb_left;
@@ -2731,7 +2768,7 @@ static int nfs_access_get_cached_rcu(struct inode *inode, const struct cred *cre 
	lh = rcu_dereference(list_tail_rcu(&nfsi->access_cache_entry_lru));

	cache = list_entry(lh, struct nfs_access_entry, lru);

	if (lh == &nfsi->access_cache_entry_lru ||

	    cred_fscmp(cred, cache->cred) != 0)

	    access_cmp(cred, cache) != 0)

		cache = NULL;

	if (cache == NULL)

		goto out;
@@ -2773,7 +2810,7 @@ static void nfs_access_add_rbtree(struct inode *inode, 
	while (*p != NULL) {

		parent = *p;

		entry = rb_entry(parent, struct nfs_access_entry, rb_node);

		cmp = cred_fscmp(cred, entry->cred);

		cmp = access_cmp(cred, entry);



		if (cmp < 0)

			p = &parent->rb_left;
@@ -2802,7 +2839,9 @@ void nfs_access_add_cache(struct inode *inode, struct nfs_access_entry *set, 
	if (cache == NULL)

		return;

	RB_CLEAR_NODE(&cache->rb_node);

	cache->cred = get_cred(cred);

	cache->fsuid = cred->fsuid;

	cache->fsgid = cred->fsgid;

	cache->group_info = get_group_info(cred->group_info);

	cache->mask = set->mask;



	/* The above field assignments must be visible
@@ -2895,7 +2934,6 @@ static int nfs_do_access(struct inode *inode, const struct cred *cred, int mask) 
		cache.mask |= NFS_ACCESS_DELETE | NFS_ACCESS_LOOKUP;

	else

		cache.mask |= NFS_ACCESS_EXECUTE;

	cache.cred = cred;

	status = NFS_PROTO(inode)->access(inode, &cache, cred);

	if (status != 0) {

		if (status == -ESTALE) {

fs/nfs/nfs4proc.c

+0 −1
Original line number Diff line number Diff line
@@ -2653,7 +2653,6 @@ static int nfs4_opendata_access(const struct cred *cred, 
	} else if ((fmode & FMODE_READ) && !opendata->file_created)

		mask = NFS4_ACCESS_READ;



	cache.cred = cred;

	nfs_access_set_mask(&cache, opendata->o_res.access_result);

	nfs_access_add_cache(state->inode, &cache, cred);

include/linux/nfs_fs.h

+3 −1
Original line number Diff line number Diff line
@@ -61,7 +61,9 @@ 
struct nfs_access_entry {

	struct rb_node		rb_node;

	struct list_head	lru;

	const struct cred *	cred;

	kuid_t			fsuid;

	kgid_t			fsgid;

	struct group_info	*group_info;

	__u32			mask;

	struct rcu_head		rcu_head;

};