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Address weakness with new pledge("anet") promise

Browse source 
The intent with pledge("anet") has been to prevent outbound connections.
However we were only doing that for TCP sockets, and outbound UDP could
still get through, by using socket() plus sendto(). This change fixed
that by preventing UDP sockets from being created.

Credit goes to chc4 on Hacker News for finding this.
This commit is contained in:
Justine Tunney 2023-06-18 18:06:47 -07:00
parent fb2bd313ae
commit 48b2afb192
No known key found for this signature in database
GPG key ID: BE714B4575D6E328
3 changed files with 74 additions and 6 deletions
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18
third_party/python/Modules/tokenbucket.c vendored
View file

@ -32,6 +32,7 @@
#include "libc/str/str.h"
#include "libc/sysv/consts/af.h"
#include "libc/sysv/consts/clock.h"
#include "libc/sysv/consts/f.h"
#include "libc/sysv/consts/sig.h"
#include "libc/sysv/consts/sock.h"
#include "libc/sysv/consts/timer.h"
@ -55,6 +56,7 @@ PYTHON_PROVIDE("tokenbucket.count");
PYTHON_PROVIDE("tokenbucket.program");
struct TokenBucket {
int fd;
int pid;
signed char cidr;
struct timespec replenish;
@ -229,7 +231,7 @@ or errno on error. To test if blackholed is running, ban 0.0.0.0.");
static PyObject *
tokenbucket_blackhole(PyObject *self, PyObject *args)
{
int fd;
int fd, fd2;
char buf[4];
uint32_t ip;
const char *ipstr;
@ -241,15 +243,21 @@ tokenbucket_blackhole(PyObject *self, PyObject *args)
PyErr_SetString(PyExc_ValueError, "bad ipv4 address");
return 0;
}
if ((fd = socket(AF_UNIX, SOCK_DGRAM, 0)) == -1) {
return PyLong_FromLong(errno);
if (!(fd = g_tokenbucket.fd)) {
if ((fd = socket(AF_UNIX, SOCK_DGRAM, 0)) == -1) {
return PyLong_FromLong(errno);
}
fd2 = fcntl(fd, F_DUPFD_CLOEXEC, 10);
close(fd);
if (fd2 == -1) {
return PyLong_FromLong(errno);
}
g_tokenbucket.fd = fd = fd2;
}
WRITE32BE(buf, ip);
if (sendto(fd, buf, 4, 0, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
close(fd);
return PyLong_FromLong(errno);
}
close(fd);
return PyLong_FromLong(0);
}