[PATCH 5.18 088/231] netfilter: nf_tables: replace BUG_ON by element length check

Greg Kroah-Hartman
2022-07-19T12:57:22Z

From: Pablo Neira Ayuso <pablo@netfilter.org>

[ Upstream commit c39ba4de6b0a843bec5d46c2b6f2064428dada5e ]

BUG_ON can be triggered from userspace with an element with a large
userdata area. Replace it by length check and return EINVAL instead.
Over time extensions have been growing in size.

Pick a sufficiently old Fixes: tag to propagate this fix.

Fixes: 7d7402642eaf ("netfilter: nf_tables: variable sized set element keys / data")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/net/netfilter/nf_tables.h | 14 ++++---
net/netfilter/nf_tables_api.c | 72 ++++++++++++++++++++++++++------------
2 files changed, 60 insertions(+), 26 deletions(-)

--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -657,18 +657,22 @@ static inline void nft_set_ext_prepare(s
tmpl->len = sizeof(struct nft_set_ext);
}

-static inline void nft_set_ext_add_length(struct nft_set_ext_tmpl *tmpl, u8 id,
- unsigned int len)
+static inline int nft_set_ext_add_length(struct nft_set_ext_tmpl *tmpl, u8 id,
+ unsigned int len)
{
tmpl->len = ALIGN(tmpl->len, nft_set_ext_types[id].align);
- BUG_ON(tmpl->len > U8_MAX);
+ if (tmpl->len > U8_MAX)
+ return -EINVAL;
+
tmpl->offset[id] = tmpl->len;
tmpl->len += nft_set_ext_types[id].len + len;
+
+ return 0;
}

-static inline void nft_set_ext_add(struct nft_set_ext_tmpl *tmpl, u8 id)
+static inline int nft_set_ext_add(struct nft_set_ext_tmpl *tmpl, u8 id)
{
- nft_set_ext_add_length(tmpl, id, 0);
+ return nft_set_ext_add_length(tmpl, id, 0);
}

static inline void nft_set_ext_init(struct nft_set_ext *ext,
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5831,8 +5831,11 @@ static int nft_add_set_elem(struct nft_c
if (!nla[NFTA_SET_ELEM_KEY] && !(flags & NFT_SET_ELEM_CATCHALL))
return -EINVAL;

- if (flags != 0)
- nft_set_ext_add(&tmpl, NFT_SET_EXT_FLAGS);
+ if (flags != 0) {
+ err = nft_set_ext_add(&tmpl, NFT_SET_EXT_FLAGS);
+ if (err < 0)
+ return err;
+ }

if (set->flags & NFT_SET_MAP) {
if (nla[NFTA_SET_ELEM_DATA] == NULL &&
@@ -5941,7 +5944,9 @@ static int nft_add_set_elem(struct nft_c
if (err < 0)
goto err_set_elem_expr;

- nft_set_ext_add_length(&tmpl, NFT_SET_EXT_KEY, set->klen);
+ err = nft_set_ext_add_length(&tmpl, NFT_SET_EXT_KEY, set->klen);
+ if (err < 0)
+ goto err_parse_key;
}

if (nla[NFTA_SET_ELEM_KEY_END]) {
@@ -5950,22 +5955,31 @@ static int nft_add_set_elem(struct nft_c
if (err < 0)
goto err_parse_key;

- nft_set_ext_add_length(&tmpl, NFT_SET_EXT_KEY_END, set->klen);
+ err = nft_set_ext_add_length(&tmpl, NFT_SET_EXT_KEY_END, set->klen);
+ if (err < 0)
+ goto err_parse_key_end;
}

if (timeout > 0) {
- nft_set_ext_add(&tmpl, NFT_SET_EXT_EXPIRATION);
- if (timeout != set->timeout)
- nft_set_ext_add(&tmpl, NFT_SET_EXT_TIMEOUT);
+ err = nft_set_ext_add(&tmpl, NFT_SET_EXT_EXPIRATION);
+ if (err < 0)
+ goto err_parse_key_end;
+
+ if (timeout != set->timeout) {
+ err = nft_set_ext_add(&tmpl, NFT_SET_EXT_TIMEOUT);
+ if (err < 0)
+ goto err_parse_key_end;
+ }
}

if (num_exprs) {
for (i = 0; i < num_exprs; i++)
size += expr_array[i]->ops->size;

- nft_set_ext_add_length(&tmpl, NFT_SET_EXT_EXPRESSIONS,
- sizeof(struct nft_set_elem_expr) +
- size);
+ err = nft_set_ext_add_length(&tmpl, NFT_SET_EXT_EXPRESSIONS,
+ sizeof(struct nft_set_elem_expr) + size);
+ if (err < 0)
+ goto err_parse_key_end;
}

if (nla[NFTA_SET_ELEM_OBJREF] != NULL) {
@@ -5980,7 +5994,9 @@ static int nft_add_set_elem(struct nft_c
err = PTR_ERR(obj);
goto err_parse_key_end;
}
- nft_set_ext_add(&tmpl, NFT_SET_EXT_OBJREF);
+ err = nft_set_ext_add(&tmpl, NFT_SET_EXT_OBJREF);
+ if (err < 0)
+ goto err_parse_key_end;
}

if (nla[NFTA_SET_ELEM_DATA] != NULL) {
@@ -6014,7 +6030,9 @@ static int nft_add_set_elem(struct nft_c
NFT_VALIDATE_NEED);
}

- nft_set_ext_add_length(&tmpl, NFT_SET_EXT_DATA, desc.len);
+ err = nft_set_ext_add_length(&tmpl, NFT_SET_EXT_DATA, desc.len);
+ if (err < 0)
+ goto err_parse_data;
}

/* The full maximum length of userdata can exceed the maximum
@@ -6024,9 +6042,12 @@ static int nft_add_set_elem(struct nft_c
ulen = 0;
if (nla[NFTA_SET_ELEM_USERDATA] != NULL) {
ulen = nla_len(nla[NFTA_SET_ELEM_USERDATA]);
- if (ulen > 0)
- nft_set_ext_add_length(&tmpl, NFT_SET_EXT_USERDATA,
- ulen);
+ if (ulen > 0) {
+ err = nft_set_ext_add_length(&tmpl, NFT_SET_EXT_USERDATA,
+ ulen);
+ if (err < 0)
+ goto err_parse_data;
+ }
}

err = -ENOMEM;
@@ -6252,8 +6273,11 @@ static int nft_del_setelem(struct nft_ct

nft_set_ext_prepare(&tmpl);

- if (flags != 0)
- nft_set_ext_add(&tmpl, NFT_SET_EXT_FLAGS);
+ if (flags != 0) {
+ err = nft_set_ext_add(&tmpl, NFT_SET_EXT_FLAGS);
+ if (err < 0)
+ return err;
+ }

if (nla[NFTA_SET_ELEM_KEY]) {
err = nft_setelem_parse_key(ctx, set, &elem.key.val,
@@ -6261,16 +6285,20 @@ static int nft_del_setelem(struct nft_ct
if (err < 0)
return err;

- nft_set_ext_add_length(&tmpl, NFT_SET_EXT_KEY, set->klen);
+ err = nft_set_ext_add_length(&tmpl, NFT_SET_EXT_KEY, set->klen);
+ if (err < 0)
+ goto fail_elem;
}

if (nla[NFTA_SET_ELEM_KEY_END]) {
err = nft_setelem_parse_key(ctx, set, &elem.key_end.val,
nla[NFTA_SET_ELEM_KEY_END]);
if (err < 0)
- return err;
+ goto fail_elem;

- nft_set_ext_add_length(&tmpl, NFT_SET_EXT_KEY_END, set->klen);
+ err = nft_set_ext_add_length(&tmpl, NFT_SET_EXT_KEY_END, set->klen);
+ if (err < 0)
+ goto fail_elem_key_end;
}

err = -ENOMEM;
@@ -6278,7 +6306,7 @@ static int nft_del_setelem(struct nft_ct
elem.key_end.val.data, NULL, 0, 0,
GFP_KERNEL_ACCOUNT);
if (elem.priv == NULL)
- goto fail_elem;
+ goto fail_elem_key_end;

ext = nft_set_elem_ext(set, elem.priv);
if (flags)
@@ -6302,6 +6330,8 @@ fail_ops:
kfree(trans);
fail_trans:
kfree(elem.priv);
+fail_elem_key_end:
+ nft_data_release(&elem.key_end.val, NFT_DATA_VALUE);
fail_elem:
nft_data_release(&elem.key.val, NFT_DATA_VALUE);
return err;