64ae13ed47
__flow_hash_consistentify() wrongly swaps ipv4 addresses in few cases.
This function is indirectly used by __skb_get_hash_symmetric(), which is
used to fanout packets in AF_PACKET.
Intrusion detection systems may be impacted by this issue.
__flow_hash_consistentify() computes the addresses difference then swaps
them if the difference is negative. In few cases src - dst and dst - src
are both negative.
The following snippet mimics __flow_hash_consistentify():
```
#include <stdio.h>
#include <stdint.h>
int main(int argc, char** argv) {
int diffs_d, diffd_s;
uint32_t dst = 0xb225a8c0; /* 178.37.168.192 --> 192.168.37.178 */
uint32_t src = 0x3225a8c0; /* 50.37.168.192 --> 192.168.37.50 */
uint32_t dst2 = 0x3325a8c0; /* 51.37.168.192 --> 192.168.37.51 */
diffs_d = src - dst;
diffd_s = dst - src;
printf("src:%08x dst:%08x, diff(s-d)=%d(0x%x) diff(d-s)=%d(0x%x)\n",
src, dst, diffs_d, diffs_d, diffd_s, diffd_s);
diffs_d = src - dst2;
diffd_s = dst2 - src;
printf("src:%08x dst:%08x, diff(s-d)=%d(0x%x) diff(d-s)=%d(0x%x)\n",
src, dst2, diffs_d, diffs_d, diffd_s, diffd_s);
return 0;
}
```
Results:
src:3225a8c0 dst:b225a8c0, \
diff(s-d)=-2147483648(0x80000000) \
diff(d-s)=-2147483648(0x80000000)
src:3225a8c0 dst:3325a8c0, \
diff(s-d)=-16777216(0xff000000) \
diff(d-s)=16777216(0x1000000)
In the first case the addresses differences are always < 0, therefore
__flow_hash_consistentify() always swaps, thus dst->src and src->dst
packets have differents hashes.
Fixes:
|
||
|---|---|---|
| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
README
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.