netfilter: fix string extension for case insensitive pattern matching
The flag XT_STRING_FLAG_IGNORECASE indicates case insensitive string matching. netfilter can find cmd.exe, Cmd.exe, cMd.exe and etc easily. A new revision 1 was added, in the meantime invert of xt_string_info was moved into flags as a flag. If revision is 1, The flag XT_STRING_FLAG_INVERT indicates invert matching. Signed-off-by: Joonwoo Park <joonwpark81@gmail.com> Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -4,6 +4,11 @@
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#define XT_STRING_MAX_PATTERN_SIZE 128
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#define XT_STRING_MAX_ALGO_NAME_SIZE 16
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enum {
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XT_STRING_FLAG_INVERT = 0x01,
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XT_STRING_FLAG_IGNORECASE = 0x02
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};
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struct xt_string_info
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{
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u_int16_t from_offset;
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@ -11,7 +16,15 @@ struct xt_string_info
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char algo[XT_STRING_MAX_ALGO_NAME_SIZE];
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char pattern[XT_STRING_MAX_PATTERN_SIZE];
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u_int8_t patlen;
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u_int8_t invert;
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union {
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struct {
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u_int8_t invert;
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} v0;
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struct {
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u_int8_t flags;
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} v1;
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} u;
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/* Used internally by the kernel */
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struct ts_config __attribute__((aligned(8))) *config;
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@ -29,12 +29,16 @@ string_mt(const struct sk_buff *skb, const struct net_device *in,
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{
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const struct xt_string_info *conf = matchinfo;
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struct ts_state state;
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int invert;
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memset(&state, 0, sizeof(struct ts_state));
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invert = (match->revision == 0 ? conf->u.v0.invert :
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conf->u.v1.flags & XT_STRING_FLAG_INVERT);
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return (skb_find_text((struct sk_buff *)skb, conf->from_offset,
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conf->to_offset, conf->config, &state)
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!= UINT_MAX) ^ conf->invert;
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!= UINT_MAX) ^ invert;
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}
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#define STRING_TEXT_PRIV(m) ((struct xt_string_info *)(m))
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@ -46,6 +50,7 @@ string_mt_check(const char *tablename, const void *ip,
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{
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struct xt_string_info *conf = matchinfo;
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struct ts_config *ts_conf;
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int flags = TS_AUTOLOAD;
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/* Damn, can't handle this case properly with iptables... */
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if (conf->from_offset > conf->to_offset)
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@ -54,8 +59,15 @@ string_mt_check(const char *tablename, const void *ip,
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return false;
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if (conf->patlen > XT_STRING_MAX_PATTERN_SIZE)
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return false;
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if (match->revision == 1) {
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if (conf->u.v1.flags &
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~(XT_STRING_FLAG_IGNORECASE | XT_STRING_FLAG_INVERT))
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return false;
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if (conf->u.v1.flags & XT_STRING_FLAG_IGNORECASE)
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flags |= TS_IGNORECASE;
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}
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ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
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GFP_KERNEL, TS_AUTOLOAD);
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GFP_KERNEL, flags);
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if (IS_ERR(ts_conf))
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return false;
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@ -72,6 +84,7 @@ static void string_mt_destroy(const struct xt_match *match, void *matchinfo)
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static struct xt_match string_mt_reg[] __read_mostly = {
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{
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.name = "string",
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.revision = 0,
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.family = AF_INET,
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.checkentry = string_mt_check,
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.match = string_mt,
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@ -81,6 +94,27 @@ static struct xt_match string_mt_reg[] __read_mostly = {
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},
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{
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.name = "string",
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.revision = 1,
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.family = AF_INET,
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.checkentry = string_mt_check,
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.match = string_mt,
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.destroy = string_mt_destroy,
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.matchsize = sizeof(struct xt_string_info),
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.me = THIS_MODULE
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},
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{
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.name = "string",
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.revision = 0,
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.family = AF_INET6,
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.checkentry = string_mt_check,
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.match = string_mt,
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.destroy = string_mt_destroy,
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.matchsize = sizeof(struct xt_string_info),
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.me = THIS_MODULE
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},
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{
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.name = "string",
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.revision = 1,
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.family = AF_INET6,
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.checkentry = string_mt_check,
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.match = string_mt,
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