netfilter: helper: add build-time asserts for helper data size

add a 32 byte scratch area in the helper struct instead of relying
on variable sized helpers plus compile-time asserts to let us know
if 32 bytes aren't enough anymore.

Not having variable sized helpers will later allow to add BUILD_BUG_ON
for the total size of conntrack extensions -- the helper extension is
the only one that doesn't have a fixed size.

The (useless!) NF_CT_HELPER_BUILD_BUG_ON(0); are added so that in case
someone adds a new helper and copy-pastes from one that doesn't store
private data at least some indication that this macro should be used
somehow is there...

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2017-04-16 01:29:15 +02:00 committed by Pablo Neira Ayuso
parent 906535b046
commit dcf67740f2
9 changed files with 20 additions and 1 deletions

View File

@ -66,9 +66,12 @@ struct nf_conn_help {
u8 expecting[NF_CT_MAX_EXPECT_CLASSES];
/* private helper information. */
char data[];
char data[32] __aligned(8);
};
#define NF_CT_HELPER_BUILD_BUG_ON(structsize) \
BUILD_BUG_ON((structsize) > FIELD_SIZEOF(struct nf_conn_help, data))
struct nf_conntrack_helper *__nf_conntrack_helper_find(const char *name,
u16 l3num, u8 protonum);

View File

@ -207,6 +207,8 @@ static int __init nf_conntrack_amanda_init(void)
{
int ret, i;
NF_CT_HELPER_BUILD_BUG_ON(0);
for (i = 0; i < ARRAY_SIZE(search); i++) {
search[i].ts = textsearch_prepare(ts_algo, search[i].string,
search[i].len,

View File

@ -577,6 +577,8 @@ static int __init nf_conntrack_ftp_init(void)
{
int i, ret = 0;
NF_CT_HELPER_BUILD_BUG_ON(sizeof(struct nf_ct_ftp_master));
ftp_buffer = kmalloc(65536, GFP_KERNEL);
if (!ftp_buffer)
return -ENOMEM;

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@ -1836,6 +1836,8 @@ static int __init nf_conntrack_h323_init(void)
{
int ret;
NF_CT_HELPER_BUILD_BUG_ON(sizeof(struct nf_ct_h323_master));
h323_buffer = kmalloc(65536, GFP_KERNEL);
if (!h323_buffer)
return -ENOMEM;

View File

@ -58,6 +58,8 @@ static struct nf_conntrack_helper helper __read_mostly = {
static int __init nf_conntrack_netbios_ns_init(void)
{
NF_CT_HELPER_BUILD_BUG_ON(0);
exp_policy.timeout = timeout;
return nf_conntrack_helper_register(&helper);
}

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@ -607,6 +607,8 @@ static struct nf_conntrack_helper pptp __read_mostly = {
static int __init nf_conntrack_pptp_init(void)
{
NF_CT_HELPER_BUILD_BUG_ON(sizeof(struct nf_ct_pptp_master));
return nf_conntrack_helper_register(&pptp);
}

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@ -184,6 +184,8 @@ static int __init nf_conntrack_sane_init(void)
{
int i, ret = 0;
NF_CT_HELPER_BUILD_BUG_ON(sizeof(struct nf_ct_sane_master));
sane_buffer = kmalloc(65536, GFP_KERNEL);
if (!sane_buffer)
return -ENOMEM;

View File

@ -1622,6 +1622,8 @@ static int __init nf_conntrack_sip_init(void)
{
int i, ret;
NF_CT_HELPER_BUILD_BUG_ON(sizeof(struct nf_ct_sip_master));
if (ports_c == 0)
ports[ports_c++] = SIP_PORT;

View File

@ -113,6 +113,8 @@ static int __init nf_conntrack_tftp_init(void)
{
int i, ret;
NF_CT_HELPER_BUILD_BUG_ON(0);
if (ports_c == 0)
ports[ports_c++] = TFTP_PORT;