netfilter: nf_tables: replace BUG_ON by element length check

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: ef5485c9b3ef ("netfilter: nf_tables: variable sized set element keys / data")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 5c4e5a96a984fdb2c9b89760202311dde4da62d1..64cf655c818cc6e0a4c9c80c21021719ddf218e8 100644 (file)
--- 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(struct nft_set_ext_tmpl *tmpl)
        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,

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index d6b59beab3a9860a0b27d0a0ae817128a6486735..646d5fd53604bd94d64770ff6a5030e617b69f72 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5833,8 +5833,11 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
        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 &&
@@ -5943,7 +5946,9 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
                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]) {
@@ -5952,22 +5957,31 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
                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) {
@@ -5982,7 +5996,9 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
                        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) {
@@ -6016,7 +6032,9 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
                                                          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
@@ -6026,9 +6044,12 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
        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;
@@ -6256,8 +6277,11 @@ static int nft_del_setelem(struct nft_ctx *ctx, struct nft_set *set,
 
        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,
@@ -6265,16 +6289,20 @@ static int nft_del_setelem(struct nft_ctx *ctx, struct nft_set *set,
                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;
@@ -6282,7 +6310,7 @@ static int nft_del_setelem(struct nft_ctx *ctx, struct nft_set *set,
                                      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)
@@ -6306,6 +6334,8 @@ 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;