TODO:
1) add a print function
2) add a save function
Signed-off-by: Arif Hossain <aftnix@xxxxxxxxx>
---
extensions/Mbuild | 1 +
extensions/libxt_OBSF.c | 150 +++++++++++++++++++++++++++++++++++++++++++++++
extensions/xt_OBSF.c | 43 ++++++++------
extensions/xt_OBSF.h | 3 +-
4 files changed, 176 insertions(+), 21 deletions(-)
create mode 100644 extensions/libxt_OBSF.c
diff --git a/extensions/Mbuild b/extensions/Mbuild
index 1c76e34..f4e5e17 100644
--- a/extensions/Mbuild
+++ b/extensions/Mbuild
@@ -26,3 +26,4 @@ obj-${build_pknock} += pknock/
obj-${build_psd} += libxt_psd.so
obj-${build_quota2} += libxt_quota2.so
obj-${build_gradm} += libxt_gradm.so
+obj-${build_OBSF} += libxt_OBSF.so
\ No newline at end of file
diff --git a/extensions/libxt_OBSF.c b/extensions/libxt_OBSF.c
new file mode 100644
index 0000000..e94c91d
--- /dev/null
+++ b/extensions/libxt_OBSF.c
@@ -0,0 +1,150 @@
+#include <stdio.h>
+#include <xtables.h>
+#include <linux/netfilter/x_tables.h>
+#include <stdlib.h>
+#include <string.h>
+#include <getopt.h>
+
+#include "xt_OBSF.h"
+#include "compat_user.h"
+
+enum {
+ O_OBSF_ENC_KEY,
+ O_OBSF_ENC_KEYLEN,
+ O_OBSF_ENC_TYPE,
+ O_OBSF_ENC_ENC_DEC,
+ O_OBSF_PAD_ENABLE,
+ O_OBSF_PAD_TYPE,
+ O_OBSF_PAD_START,
+ O_OBSF_PAD_STOP,
+};
+
+enum {
+ F_OBSF_ENC_KEY = 1 << O_OBSF_ENC_KEY,
+ F_OBSF_ENC_TYPE = 1 << O_OBSF_ENC_TYPE,
+ F_OBSF_PAD_TYPE = 1 << O_OBSF_PAD_TYPE,
+ F_OBSF_PAD_START = 1 << O_OBSF_PAD_START,
+ F_OBSF_PAD_STOP = 1 << O_OBSF_PAD_STOP,
+};
+
+static void OBSF_help(void)
+{
+ printf(
+ "OBSF target obtions\n"
+ " --key key --enc-type type aes/arc4 --dec"
+ "key is <32 byte valued"
+ "default is encryption, --dec for decryption"
+ " --pad to enable padding --pad-type static/random --start start value ---end end value"
+ "start/end value 0-255"
+ "start > end"
+ ""
+ );
+}
+
+
+static const struct xt_option_entry OBSF_opts[] = {
+ {
+ .name = "key",
+ .id = O_OBSF_ENC_KEY,
+ .type = XTTYPE_STRING,
+ .flags = XTOPT_PUT,
+ XTOPT_POINTER(struct xt_OBSF_tginfo,key),
+ },
+ {
+ .name = "enc_type",
+ .id = O_OBSF_ENC_TYPE,
+ .type = XTTYPE_STRING,
+ },
+ {
+ .name = "dec",
+ .id = O_OBSF_ENC_ENC_DEC,
+ .type = XTTYPE_NONE,
+ },
+ {
+ .name = "pad",
+ .id = O_OBSF_PAD_ENABLE,
+ .type = XTTYPE_NONE,
+ },
+ {
+ .name = "pad-type",
+ .id = O_OBSF_PAD_TYPE,
+ .type = XTTYPE_STRING,
+ },
+ {
+ .name = "start",
+ .id = O_OBSF_PAD_START,
+ .type = XTTYPE_UINT8,
+ .flags = XTOPT_PUT,
+ XTOPT_POINTER(struct xt_OBSF_tginfo,start),
+ },
+ {
+ .name = "end",
+ .id = O_OBSF_PAD_STOP,
+ .type = XTTYPE_UINT8,
+ .flags = XTOPT_PUT,
+ XTOPT_POINTER(struct xt_OBSF_tginfo,end)
+ },
+ XTOPT_TABLEEND,
+};
+
+static void OBSF_parse(struct xt_option_call *cb)
+{
+ struct xt_OBSF_tginfo *info = cb->data;
+ xtables_option_parse(cb);
+
+ switch(cb->entry->id) {
+ case O_OBSF_ENC_KEY:
+ info->key_len = (__u8)strlen(cb->arg);
+ break;
+ case O_OBSF_ENC_TYPE:
+ if ((strcmp(cb->arg,"arc4")) == 0)
+ info->flags |= XT_OBSF_ENC_ARC4;
+ else if ((strcmp(cb->arg,"aes")) == 0)
+ info->flags |= XT_OBSF_ENC_AES;
+ break;
+ case O_OBSF_ENC_ENC_DEC:
+ info->flags |= XT_OBSF_ENC_DEC;
+ break;
+ case O_OBSF_PAD_ENABLE:
+ info->flags |= XT_OBSF_PAD_ENABLED;
+ break;
+ case O_OBSF_PAD_TYPE:
+ if ((strcmp(cb->arg,"static")) == 0)
+ info->flags |= XT_OBSF_PAD_STATIC;
+ else if ((strcmp(cb->arg,"random")) == 0)
+ info->flags |= XT_OBSF_PAD_RANDOM;
+ break;
+ }
+ if (!(info->flags & XT_OBSF_ENC_DEC))
+ info->flags |= XT_OBSF_ENC_ENC;
+
+ /* padding addition, removal will be dealt in target considering from which
+ * hook the packet arrived, same can be done for ENC/DEC
+ */
+
+
+}
+
+
+static void OBSF_print(const void *ip,
+ const struct xt_entry_target *target, int numeric)
+{
+}
+
+
+static void OBSF_save(const void *ip, const struct xt_entry_target *target)
+{
+}
+
+
+static struct xtables_target obsf_target = {
+ .family = NFPROTO_UNSPEC,
+ .name = "OBSF",
+ .version = XTABLES_VERSION,
+ .size = XT_ALIGN(sizeof(struct xt_OBSF_tginfo)),
+ .userspacesize = XT_ALIGN(sizeof(struct xt_OBSF_tginfo) - sizeof(struct xt_obsf_priv *)),
+ .help = OBSF_help,
+ .print = OBSF_print,
+ .save = OBSF_save,
+ .x6_options = OBSF_opts,
+};
diff --git a/extensions/xt_OBSF.c b/extensions/xt_OBSF.c
index b997133..8fdf6e9 100644
--- a/extensions/xt_OBSF.c
+++ b/extensions/xt_OBSF.c
@@ -7,7 +7,7 @@
#include <linux/netfilter.h>
#include <linux/netfilter/x_tables.h>
-#include <linux/netfilter/xt_OBSF.h>
+#include "xt_OBSF.h"
#include <linux/crypto.h>
#include <linux/scatterlist.h>
@@ -62,28 +62,33 @@ static unsigned int obsf_tg(struct sk_buff *skb, const struct xt_action_param *p
if (info->flags & XT_OBSF_ENC_DEC)
crypto_blkcipher_decrypt(&desc, &sg, &sg, data_len);
- }
+ }
- if (info->flags & XT_OBSF_PAD_STATIC) {
- if (info->flags & XT_OBSF_PAD_ADD) {
- /* Add flase bytes */
- }
+ /* using hook to determine whether to add or remove false bytes */
- if (info->flags & XT_OBSF_PAD_REM) {
- /* Remove false bytes */
+ if (info->flags & XT_OBSF_PAD_ENABLED) {
+ if (info->flags & XT_OBSF_PAD_STATIC) {
+ if ((par->hooknum) == NF_INET_PRE_ROUTING ) {
+ /* remove padding */
+ }
+ else if ((par->hooknum) == NF_INET_LOCAL_OUT) {
+ /* add padding */
+ }
}
- }
+ else if (info->flags & XT_OBSF_PAD_RANDOM) {
+ if ((par->hooknum) == NF_INET_PRE_ROUTING ) {
- if (info->flags & XT_OBSF_PAD_RANDOM) {
- if (info->flags & XT_OBSF_PAD_ADD) {
- /* Add flase bytes */
- }
+ /* remove padding */
+
+ }
+ else if ((par->hooknum) == NF_INET_LOCAL_OUT) {
+
+ /* add padding */
+ }
- if (info->flags & XT_OBSF_PAD_REM) {
- /* Remove false bytes */
}
- }
+ }
return NF_ACCEPT;
}
@@ -119,9 +124,9 @@ static int obsf_tg_check(const struct xt_tgchk_param *par)
if ((info->flags & XT_OBSF_PAD_STATIC) && (info->flags & XT_OBSF_PAD_RANDOM))
return -EINVAL;
- if ((info->flags & XT_OBSF_PAD_ADD) & (info->flags & XT_OBSF_PAD_REM))
- return -EINVAL;
-
+ if ((info->flags & XT_OBSF_PAD_ENABLED))
+ if (((info->flags & XT_OBSF_PAD_STATIC)) | ((info->flags & XT_OBSF_PAD_RANDOM)))
+ return -EINVAL;
return 0;
/* failover */
diff --git a/extensions/xt_OBSF.h b/extensions/xt_OBSF.h
index 9d68c72..e99c048 100644
--- a/extensions/xt_OBSF.h
+++ b/extensions/xt_OBSF.h
@@ -9,8 +9,7 @@ enum {
XT_OBSF_PAD_RANDOM = 1 << 3,
XT_OBSF_ENC_ENC = 1 << 4,
XT_OBSF_ENC_DEC = 1 << 5,
- XT_OBSF_PAD_ADD = 1 << 6,
- XT_OBSF_PAD_REM = 1 << 7
+ XT_OBSF_PAD_ENABLED = 1 << 6,
};
--
1.7.1
--
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