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Subject[PATCH 5.0 003/117] netfilter: nft_compat: use .release_ops and remove list of extension
Date
[ Upstream commit b8e204006340b7aaf32bd2b9806c692f6e0cb38a ]

Add .release_ops, that is called in case of error at a later stage in
the expression initialization path, ie. .select_ops() has been already
set up operations and that needs to be undone. This allows us to unwind
.select_ops from the error path, ie. release the dynamic operations for
this extension.

Moreover, allocate one single operation instead of recycling them, this
comes at the cost of consuming a bit more memory per rule, but it
simplifies the infrastructure.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/net/netfilter/nf_tables.h | 3 +
net/netfilter/nf_tables_api.c | 7 +-
net/netfilter/nft_compat.c | 281 ++++++------------------------
3 files changed, 64 insertions(+), 227 deletions(-)

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 3d58acf94dd2..0612439909dc 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -691,10 +691,12 @@ static inline void nft_set_gc_batch_add(struct nft_set_gc_batch *gcb,
gcb->elems[gcb->head.cnt++] = elem;
}

+struct nft_expr_ops;
/**
* struct nft_expr_type - nf_tables expression type
*
* @select_ops: function to select nft_expr_ops
+ * @release_ops: release nft_expr_ops
* @ops: default ops, used when no select_ops functions is present
* @list: used internally
* @name: Identifier
@@ -707,6 +709,7 @@ static inline void nft_set_gc_batch_add(struct nft_set_gc_batch *gcb,
struct nft_expr_type {
const struct nft_expr_ops *(*select_ops)(const struct nft_ctx *,
const struct nlattr * const tb[]);
+ void (*release_ops)(const struct nft_expr_ops *ops);
const struct nft_expr_ops *ops;
struct list_head list;
const char *name;
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index e1724f9d8b9d..dc3670f2860e 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -2129,6 +2129,7 @@ struct nft_expr *nft_expr_init(const struct nft_ctx *ctx,
{
struct nft_expr_info info;
struct nft_expr *expr;
+ struct module *owner;
int err;

err = nf_tables_expr_parse(ctx, nla, &info);
@@ -2148,7 +2149,11 @@ struct nft_expr *nft_expr_init(const struct nft_ctx *ctx,
err3:
kfree(expr);
err2:
- module_put(info.ops->type->owner);
+ owner = info.ops->type->owner;
+ if (info.ops->type->release_ops)
+ info.ops->type->release_ops(info.ops);
+
+ module_put(owner);
err1:
return ERR_PTR(err);
}
diff --git a/net/netfilter/nft_compat.c b/net/netfilter/nft_compat.c
index 0a4bad55a8aa..469f9da5073b 100644
--- a/net/netfilter/nft_compat.c
+++ b/net/netfilter/nft_compat.c
@@ -22,23 +22,6 @@
#include <linux/netfilter_bridge/ebtables.h>
#include <linux/netfilter_arp/arp_tables.h>
#include <net/netfilter/nf_tables.h>
-#include <net/netns/generic.h>
-
-struct nft_xt {
- struct list_head head;
- struct nft_expr_ops ops;
- refcount_t refcnt;
-
- /* used only when transaction mutex is locked */
- unsigned int listcnt;
-
- /* Unlike other expressions, ops doesn't have static storage duration.
- * nft core assumes they do. We use kfree_rcu so that nft core can
- * can check expr->ops->size even after nft_compat->destroy() frees
- * the nft_xt struct that holds the ops structure.
- */
- struct rcu_head rcu_head;
-};

/* Used for matches where *info is larger than X byte */
#define NFT_MATCH_LARGE_THRESH 192
@@ -47,46 +30,6 @@ struct nft_xt_match_priv {
void *info;
};

-struct nft_compat_net {
- struct list_head nft_target_list;
- struct list_head nft_match_list;
-};
-
-static unsigned int nft_compat_net_id __read_mostly;
-static struct nft_expr_type nft_match_type;
-static struct nft_expr_type nft_target_type;
-
-static struct nft_compat_net *nft_compat_pernet(struct net *net)
-{
- return net_generic(net, nft_compat_net_id);
-}
-
-static void nft_xt_get(struct nft_xt *xt)
-{
- /* refcount_inc() warns on 0 -> 1 transition, but we can't
- * init the reference count to 1 in .select_ops -- we can't
- * undo such an increase when another expression inside the same
- * rule fails afterwards.
- */
- if (xt->listcnt == 0)
- refcount_set(&xt->refcnt, 1);
- else
- refcount_inc(&xt->refcnt);
-
- xt->listcnt++;
-}
-
-static bool nft_xt_put(struct nft_xt *xt)
-{
- if (refcount_dec_and_test(&xt->refcnt)) {
- WARN_ON_ONCE(!list_empty(&xt->head));
- kfree_rcu(xt, rcu_head);
- return true;
- }
-
- return false;
-}
-
static int nft_compat_chain_validate_dependency(const struct nft_ctx *ctx,
const char *tablename)
{
@@ -281,7 +224,6 @@ nft_target_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
struct xt_target *target = expr->ops->data;
struct xt_tgchk_param par;
size_t size = XT_ALIGN(nla_len(tb[NFTA_TARGET_INFO]));
- struct nft_xt *nft_xt;
u16 proto = 0;
bool inv = false;
union nft_entry e = {};
@@ -305,8 +247,6 @@ nft_target_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
if (!target->target)
return -EINVAL;

- nft_xt = container_of(expr->ops, struct nft_xt, ops);
- nft_xt_get(nft_xt);
return 0;
}

@@ -325,8 +265,8 @@ nft_target_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
if (par.target->destroy != NULL)
par.target->destroy(&par);

- if (nft_xt_put(container_of(expr->ops, struct nft_xt, ops)))
- module_put(me);
+ module_put(me);
+ kfree(expr->ops);
}

static int nft_extension_dump_info(struct sk_buff *skb, int attr,
@@ -499,7 +439,6 @@ __nft_match_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
struct xt_match *match = expr->ops->data;
struct xt_mtchk_param par;
size_t size = XT_ALIGN(nla_len(tb[NFTA_MATCH_INFO]));
- struct nft_xt *nft_xt;
u16 proto = 0;
bool inv = false;
union nft_entry e = {};
@@ -515,13 +454,7 @@ __nft_match_init(const struct nft_ctx *ctx, const struct nft_expr *expr,

nft_match_set_mtchk_param(&par, ctx, match, info, &e, proto, inv);

- ret = xt_check_match(&par, size, proto, inv);
- if (ret < 0)
- return ret;
-
- nft_xt = container_of(expr->ops, struct nft_xt, ops);
- nft_xt_get(nft_xt);
- return 0;
+ return xt_check_match(&par, size, proto, inv);
}

static int
@@ -564,8 +497,8 @@ __nft_match_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr,
if (par.match->destroy != NULL)
par.match->destroy(&par);

- if (nft_xt_put(container_of(expr->ops, struct nft_xt, ops)))
- module_put(me);
+ module_put(me);
+ kfree(expr->ops);
}

static void
@@ -574,18 +507,6 @@ nft_match_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
__nft_match_destroy(ctx, expr, nft_expr_priv(expr));
}

-static void nft_compat_deactivate(const struct nft_ctx *ctx,
- const struct nft_expr *expr,
- enum nft_trans_phase phase)
-{
- struct nft_xt *xt = container_of(expr->ops, struct nft_xt, ops);
-
- if (phase == NFT_TRANS_ABORT || phase == NFT_TRANS_COMMIT) {
- if (--xt->listcnt == 0)
- list_del_init(&xt->head);
- }
-}
-
static void
nft_match_large_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
{
@@ -780,19 +701,13 @@ static const struct nfnetlink_subsystem nfnl_compat_subsys = {
.cb = nfnl_nft_compat_cb,
};

-static bool nft_match_cmp(const struct xt_match *match,
- const char *name, u32 rev, u32 family)
-{
- return strcmp(match->name, name) == 0 && match->revision == rev &&
- (match->family == NFPROTO_UNSPEC || match->family == family);
-}
+static struct nft_expr_type nft_match_type;

static const struct nft_expr_ops *
nft_match_select_ops(const struct nft_ctx *ctx,
const struct nlattr * const tb[])
{
- struct nft_compat_net *cn;
- struct nft_xt *nft_match;
+ struct nft_expr_ops *ops;
struct xt_match *match;
unsigned int matchsize;
char *mt_name;
@@ -808,16 +723,6 @@ nft_match_select_ops(const struct nft_ctx *ctx,
rev = ntohl(nla_get_be32(tb[NFTA_MATCH_REV]));
family = ctx->family;

- cn = nft_compat_pernet(ctx->net);
-
- /* Re-use the existing match if it's already loaded. */
- list_for_each_entry(nft_match, &cn->nft_match_list, head) {
- struct xt_match *match = nft_match->ops.data;
-
- if (nft_match_cmp(match, mt_name, rev, family))
- return &nft_match->ops;
- }
-
match = xt_request_find_match(family, mt_name, rev);
if (IS_ERR(match))
return ERR_PTR(-ENOENT);
@@ -827,65 +732,62 @@ nft_match_select_ops(const struct nft_ctx *ctx,
goto err;
}

- /* This is the first time we use this match, allocate operations */
- nft_match = kzalloc(sizeof(struct nft_xt), GFP_KERNEL);
- if (nft_match == NULL) {
+ ops = kzalloc(sizeof(struct nft_expr_ops), GFP_KERNEL);
+ if (!ops) {
err = -ENOMEM;
goto err;
}

- refcount_set(&nft_match->refcnt, 0);
- nft_match->ops.type = &nft_match_type;
- nft_match->ops.eval = nft_match_eval;
- nft_match->ops.init = nft_match_init;
- nft_match->ops.destroy = nft_match_destroy;
- nft_match->ops.deactivate = nft_compat_deactivate;
- nft_match->ops.dump = nft_match_dump;
- nft_match->ops.validate = nft_match_validate;
- nft_match->ops.data = match;
+ ops->type = &nft_match_type;
+ ops->eval = nft_match_eval;
+ ops->init = nft_match_init;
+ ops->destroy = nft_match_destroy;
+ ops->dump = nft_match_dump;
+ ops->validate = nft_match_validate;
+ ops->data = match;

matchsize = NFT_EXPR_SIZE(XT_ALIGN(match->matchsize));
if (matchsize > NFT_MATCH_LARGE_THRESH) {
matchsize = NFT_EXPR_SIZE(sizeof(struct nft_xt_match_priv));

- nft_match->ops.eval = nft_match_large_eval;
- nft_match->ops.init = nft_match_large_init;
- nft_match->ops.destroy = nft_match_large_destroy;
- nft_match->ops.dump = nft_match_large_dump;
+ ops->eval = nft_match_large_eval;
+ ops->init = nft_match_large_init;
+ ops->destroy = nft_match_large_destroy;
+ ops->dump = nft_match_large_dump;
}

- nft_match->ops.size = matchsize;
+ ops->size = matchsize;

- nft_match->listcnt = 0;
- list_add(&nft_match->head, &cn->nft_match_list);
-
- return &nft_match->ops;
+ return ops;
err:
module_put(match->me);
return ERR_PTR(err);
}

+static void nft_match_release_ops(const struct nft_expr_ops *ops)
+{
+ struct xt_match *match = ops->data;
+
+ module_put(match->me);
+ kfree(ops);
+}
+
static struct nft_expr_type nft_match_type __read_mostly = {
.name = "match",
.select_ops = nft_match_select_ops,
+ .release_ops = nft_match_release_ops,
.policy = nft_match_policy,
.maxattr = NFTA_MATCH_MAX,
.owner = THIS_MODULE,
};

-static bool nft_target_cmp(const struct xt_target *tg,
- const char *name, u32 rev, u32 family)
-{
- return strcmp(tg->name, name) == 0 && tg->revision == rev &&
- (tg->family == NFPROTO_UNSPEC || tg->family == family);
-}
+static struct nft_expr_type nft_target_type;

static const struct nft_expr_ops *
nft_target_select_ops(const struct nft_ctx *ctx,
const struct nlattr * const tb[])
{
- struct nft_compat_net *cn;
- struct nft_xt *nft_target;
+ struct nft_expr_ops *ops;
struct xt_target *target;
char *tg_name;
u32 rev, family;
@@ -905,18 +807,6 @@ nft_target_select_ops(const struct nft_ctx *ctx,
strcmp(tg_name, "standard") == 0)
return ERR_PTR(-EINVAL);

- cn = nft_compat_pernet(ctx->net);
- /* Re-use the existing target if it's already loaded. */
- list_for_each_entry(nft_target, &cn->nft_target_list, head) {
- struct xt_target *target = nft_target->ops.data;
-
- if (!target->target)
- continue;
-
- if (nft_target_cmp(target, tg_name, rev, family))
- return &nft_target->ops;
- }
-
target = xt_request_find_target(family, tg_name, rev);
if (IS_ERR(target))
return ERR_PTR(-ENOENT);
@@ -931,113 +821,55 @@ nft_target_select_ops(const struct nft_ctx *ctx,
goto err;
}

- /* This is the first time we use this target, allocate operations */
- nft_target = kzalloc(sizeof(struct nft_xt), GFP_KERNEL);
- if (nft_target == NULL) {
+ ops = kzalloc(sizeof(struct nft_expr_ops), GFP_KERNEL);
+ if (!ops) {
err = -ENOMEM;
goto err;
}

- refcount_set(&nft_target->refcnt, 0);
- nft_target->ops.type = &nft_target_type;
- nft_target->ops.size = NFT_EXPR_SIZE(XT_ALIGN(target->targetsize));
- nft_target->ops.init = nft_target_init;
- nft_target->ops.destroy = nft_target_destroy;
- nft_target->ops.deactivate = nft_compat_deactivate;
- nft_target->ops.dump = nft_target_dump;
- nft_target->ops.validate = nft_target_validate;
- nft_target->ops.data = target;
+ ops->type = &nft_target_type;
+ ops->size = NFT_EXPR_SIZE(XT_ALIGN(target->targetsize));
+ ops->init = nft_target_init;
+ ops->destroy = nft_target_destroy;
+ ops->dump = nft_target_dump;
+ ops->validate = nft_target_validate;
+ ops->data = target;

if (family == NFPROTO_BRIDGE)
- nft_target->ops.eval = nft_target_eval_bridge;
+ ops->eval = nft_target_eval_bridge;
else
- nft_target->ops.eval = nft_target_eval_xt;
-
- nft_target->listcnt = 0;
- list_add(&nft_target->head, &cn->nft_target_list);
+ ops->eval = nft_target_eval_xt;

- return &nft_target->ops;
+ return ops;
err:
module_put(target->me);
return ERR_PTR(err);
}

+static void nft_target_release_ops(const struct nft_expr_ops *ops)
+{
+ struct xt_target *target = ops->data;
+
+ module_put(target->me);
+ kfree(ops);
+}
+
static struct nft_expr_type nft_target_type __read_mostly = {
.name = "target",
.select_ops = nft_target_select_ops,
+ .release_ops = nft_target_release_ops,
.policy = nft_target_policy,
.maxattr = NFTA_TARGET_MAX,
.owner = THIS_MODULE,
};

-static int __net_init nft_compat_init_net(struct net *net)
-{
- struct nft_compat_net *cn = nft_compat_pernet(net);
-
- INIT_LIST_HEAD(&cn->nft_target_list);
- INIT_LIST_HEAD(&cn->nft_match_list);
-
- return 0;
-}
-
-static void __net_exit nft_compat_exit_net(struct net *net)
-{
- struct nft_compat_net *cn = nft_compat_pernet(net);
- struct nft_xt *xt, *next;
-
- if (list_empty(&cn->nft_match_list) &&
- list_empty(&cn->nft_target_list))
- return;
-
- /* If there was an error that caused nft_xt expr to not be initialized
- * fully and noone else requested the same expression later, the lists
- * contain 0-refcount entries that still hold module reference.
- *
- * Clean them here.
- */
- mutex_lock(&net->nft.commit_mutex);
- list_for_each_entry_safe(xt, next, &cn->nft_target_list, head) {
- struct xt_target *target = xt->ops.data;
-
- list_del_init(&xt->head);
-
- if (refcount_read(&xt->refcnt))
- continue;
- module_put(target->me);
- kfree(xt);
- }
-
- list_for_each_entry_safe(xt, next, &cn->nft_match_list, head) {
- struct xt_match *match = xt->ops.data;
-
- list_del_init(&xt->head);
-
- if (refcount_read(&xt->refcnt))
- continue;
- module_put(match->me);
- kfree(xt);
- }
- mutex_unlock(&net->nft.commit_mutex);
-}
-
-static struct pernet_operations nft_compat_net_ops = {
- .init = nft_compat_init_net,
- .exit = nft_compat_exit_net,
- .id = &nft_compat_net_id,
- .size = sizeof(struct nft_compat_net),
-};
-
static int __init nft_compat_module_init(void)
{
int ret;

- ret = register_pernet_subsys(&nft_compat_net_ops);
- if (ret < 0)
- goto err_target;
-
ret = nft_register_expr(&nft_match_type);
if (ret < 0)
- goto err_pernet;
+ return ret;

ret = nft_register_expr(&nft_target_type);
if (ret < 0)
@@ -1054,8 +886,6 @@ static int __init nft_compat_module_init(void)
nft_unregister_expr(&nft_target_type);
err_match:
nft_unregister_expr(&nft_match_type);
-err_pernet:
- unregister_pernet_subsys(&nft_compat_net_ops);
return ret;
}

@@ -1064,7 +894,6 @@ static void __exit nft_compat_module_exit(void)
nfnetlink_subsys_unregister(&nfnl_compat_subsys);
nft_unregister_expr(&nft_target_type);
nft_unregister_expr(&nft_match_type);
- unregister_pernet_subsys(&nft_compat_net_ops);
}

MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_NFT_COMPAT);
--
2.19.1


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