* [PATCH] conf: Add command line switch to enable IP_FREEBIND socket option
@ 2024-10-02 4:47 David Gibson
2024-10-02 7:16 ` Stefano Brivio
0 siblings, 1 reply; 3+ messages in thread
From: David Gibson @ 2024-10-02 4:47 UTC (permalink / raw)
To: Stefano Brivio, passt-dev; +Cc: David Gibson
In a couple of recent reports, we've seen that it can be useful for pasta
to forward ports from addresses which are not currently configured on the
host, but might be in future. That can be done with the sysctl
net.ipv4.ip_nonlocal_bind, but that does require CAP_NET_ADMIN to set in
the first place. We can allow the same thing on a per-socket basis with
the IP_FREEBIND (or IPV6_FREEBIND) socket option.
Add a --freebind command line argument to enable this socket option on
all listening sockets.
Link: https://bugs.passt.top/show_bug.cgi?id=101
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
conf.c | 2 ++
passt.1 | 6 ++++++
passt.h | 1 +
util.c | 15 +++++++++++++++
4 files changed, 24 insertions(+)
diff --git a/conf.c b/conf.c
index 6e62510..84aa89d 100644
--- a/conf.c
+++ b/conf.c
@@ -836,6 +836,7 @@ static void usage(const char *name, FILE *f, int status)
" --no-ndp Disable NDP responses\n"
" --no-dhcpv6 Disable DHCPv6 server\n"
" --no-ra Disable router advertisements\n"
+ " --freebind Allow forwarding from any address\n"
" --no-map-gw Don't map gateway address to host\n"
" -4, --ipv4-only Enable IPv4 operation only\n"
" -6, --ipv6-only Enable IPv6 operation only\n");
@@ -1255,6 +1256,7 @@ void conf(struct ctx *c, int argc, char **argv)
{"no-dhcpv6", no_argument, &c->no_dhcpv6, 1 },
{"no-ndp", no_argument, &c->no_ndp, 1 },
{"no-ra", no_argument, &c->no_ra, 1 },
+ {"freebind", no_argument, &c->freebind, 1 },
{"no-map-gw", no_argument, &no_map_gw, 1 },
{"ipv4-only", no_argument, NULL, '4' },
{"ipv6-only", no_argument, NULL, '6' },
diff --git a/passt.1 b/passt.1
index 79d134d..a2547f8 100644
--- a/passt.1
+++ b/passt.1
@@ -327,6 +327,12 @@ namespace will be silently dropped.
Disable Router Advertisements. Router Solicitations coming from guest or target
namespace will be ignored.
+.TP
+.BR \-\-freebind
+Allow forwarding from addresses which are not configured on the host,
+but might be in future. This enables the \fBIP_FREEBIND\fR or
+\fBIPB6_FREEBIND\fR option on listening sockets.
+
.TP
.BR \-\-map-host-loopback " " \fIaddr
Translate \fIaddr\fR to refer to the host. Packets from the guest to
diff --git a/passt.h b/passt.h
index 031c9b6..e00049e 100644
--- a/passt.h
+++ b/passt.h
@@ -284,6 +284,7 @@ struct ctx {
int no_dhcpv6;
int no_ndp;
int no_ra;
+ int freebind;
int low_wmem;
int low_rmem;
diff --git a/util.c b/util.c
index ebd93ed..96e3de8 100644
--- a/util.c
+++ b/util.c
@@ -52,6 +52,7 @@ int sock_l4_sa(const struct ctx *c, enum epoll_type type,
{
sa_family_t af = ((const struct sockaddr *)sa)->sa_family;
union epoll_ref ref = { .type = type, .data = data };
+ bool freebind = false;
struct epoll_event ev;
int fd, y = 1, ret;
uint8_t proto;
@@ -61,8 +62,11 @@ int sock_l4_sa(const struct ctx *c, enum epoll_type type,
case EPOLL_TYPE_TCP_LISTEN:
proto = IPPROTO_TCP;
socktype = SOCK_STREAM | SOCK_NONBLOCK;
+ freebind = c->freebind;
break;
case EPOLL_TYPE_UDP_LISTEN:
+ freebind = c->freebind;
+ /* fallthrough */
case EPOLL_TYPE_UDP_REPLY:
proto = IPPROTO_UDP;
socktype = SOCK_DGRAM | SOCK_NONBLOCK;
@@ -127,6 +131,17 @@ int sock_l4_sa(const struct ctx *c, enum epoll_type type,
}
}
+ if (freebind) {
+ int level = af == AF_INET ? IPPROTO_IP : IPPROTO_IPV6;
+ int opt = af == AF_INET ? IP_FREEBIND : IPV6_FREEBIND;
+
+ if (setsockopt(fd, level, opt, &y, sizeof(y))) {
+ err_perror("Failed to set %s on socket %i",
+ af == AF_INET ? "IP_FREEBIND" : "IPV6_FREEBIND",
+ fd);
+ }
+ }
+
if (bind(fd, sa, sl) < 0) {
/* We'll fail to bind to low ports if we don't have enough
* capabilities, and we'll fail to bind on already bound ports,
--
@@ -52,6 +52,7 @@ int sock_l4_sa(const struct ctx *c, enum epoll_type type,
{
sa_family_t af = ((const struct sockaddr *)sa)->sa_family;
union epoll_ref ref = { .type = type, .data = data };
+ bool freebind = false;
struct epoll_event ev;
int fd, y = 1, ret;
uint8_t proto;
@@ -61,8 +62,11 @@ int sock_l4_sa(const struct ctx *c, enum epoll_type type,
case EPOLL_TYPE_TCP_LISTEN:
proto = IPPROTO_TCP;
socktype = SOCK_STREAM | SOCK_NONBLOCK;
+ freebind = c->freebind;
break;
case EPOLL_TYPE_UDP_LISTEN:
+ freebind = c->freebind;
+ /* fallthrough */
case EPOLL_TYPE_UDP_REPLY:
proto = IPPROTO_UDP;
socktype = SOCK_DGRAM | SOCK_NONBLOCK;
@@ -127,6 +131,17 @@ int sock_l4_sa(const struct ctx *c, enum epoll_type type,
}
}
+ if (freebind) {
+ int level = af == AF_INET ? IPPROTO_IP : IPPROTO_IPV6;
+ int opt = af == AF_INET ? IP_FREEBIND : IPV6_FREEBIND;
+
+ if (setsockopt(fd, level, opt, &y, sizeof(y))) {
+ err_perror("Failed to set %s on socket %i",
+ af == AF_INET ? "IP_FREEBIND" : "IPV6_FREEBIND",
+ fd);
+ }
+ }
+
if (bind(fd, sa, sl) < 0) {
/* We'll fail to bind to low ports if we don't have enough
* capabilities, and we'll fail to bind on already bound ports,
--
2.46.2
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] conf: Add command line switch to enable IP_FREEBIND socket option
2024-10-02 4:47 [PATCH] conf: Add command line switch to enable IP_FREEBIND socket option David Gibson
@ 2024-10-02 7:16 ` Stefano Brivio
2024-10-03 3:25 ` David Gibson
0 siblings, 1 reply; 3+ messages in thread
From: Stefano Brivio @ 2024-10-02 7:16 UTC (permalink / raw)
To: David Gibson; +Cc: passt-dev
On Wed, 2 Oct 2024 14:47:16 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:
> In a couple of recent reports, we've seen that it can be useful for pasta
> to forward ports from addresses which are not currently configured on the
> host, but might be in future. That can be done with the sysctl
> net.ipv4.ip_nonlocal_bind, but that does require CAP_NET_ADMIN to set in
> the first place. We can allow the same thing on a per-socket basis with
> the IP_FREEBIND (or IPV6_FREEBIND) socket option.
>
> Add a --freebind command line argument to enable this socket option on
> all listening sockets.
>
> Link: https://bugs.passt.top/show_bug.cgi?id=101
>
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> ---
> conf.c | 2 ++
> passt.1 | 6 ++++++
> passt.h | 1 +
> util.c | 15 +++++++++++++++
> 4 files changed, 24 insertions(+)
>
> diff --git a/conf.c b/conf.c
> index 6e62510..84aa89d 100644
> --- a/conf.c
> +++ b/conf.c
> @@ -836,6 +836,7 @@ static void usage(const char *name, FILE *f, int status)
> " --no-ndp Disable NDP responses\n"
> " --no-dhcpv6 Disable DHCPv6 server\n"
> " --no-ra Disable router advertisements\n"
> + " --freebind Allow forwarding from any address\n"
I think "from any address" might be a bit ambiguous, because it could
also be read as "Allow forwarding traffic coming from any address",
which is allowed regardless.
What about:
" --freebind Allow any address for forwarding\n"
?
> " --no-map-gw Don't map gateway address to host\n"
> " -4, --ipv4-only Enable IPv4 operation only\n"
> " -6, --ipv6-only Enable IPv6 operation only\n");
> @@ -1255,6 +1256,7 @@ void conf(struct ctx *c, int argc, char **argv)
> {"no-dhcpv6", no_argument, &c->no_dhcpv6, 1 },
> {"no-ndp", no_argument, &c->no_ndp, 1 },
> {"no-ra", no_argument, &c->no_ra, 1 },
> + {"freebind", no_argument, &c->freebind, 1 },
> {"no-map-gw", no_argument, &no_map_gw, 1 },
> {"ipv4-only", no_argument, NULL, '4' },
> {"ipv6-only", no_argument, NULL, '6' },
> diff --git a/passt.1 b/passt.1
> index 79d134d..a2547f8 100644
> --- a/passt.1
> +++ b/passt.1
> @@ -327,6 +327,12 @@ namespace will be silently dropped.
> Disable Router Advertisements. Router Solicitations coming from guest or target
> namespace will be ignored.
>
> +.TP
> +.BR \-\-freebind
> +Allow forwarding from addresses which are not configured on the host,
Same here, it could also be read as "Allow forwarding traffic coming
from addresses ...".
Perhaps:
Allow binding to addresses which are not configured on the host (but
might be in the future) for port forwarding.
?
> +but might be in future. This enables the \fBIP_FREEBIND\fR or
> +\fBIPB6_FREEBIND\fR option on listening sockets.
> +
> .TP
> .BR \-\-map-host-loopback " " \fIaddr
> Translate \fIaddr\fR to refer to the host. Packets from the guest to
> diff --git a/passt.h b/passt.h
> index 031c9b6..e00049e 100644
> --- a/passt.h
> +++ b/passt.h
> @@ -284,6 +284,7 @@ struct ctx {
> int no_dhcpv6;
> int no_ndp;
> int no_ra;
> + int freebind;
Missing update to struct comment.
>
> int low_wmem;
> int low_rmem;
> diff --git a/util.c b/util.c
> index ebd93ed..96e3de8 100644
> --- a/util.c
> +++ b/util.c
> @@ -52,6 +52,7 @@ int sock_l4_sa(const struct ctx *c, enum epoll_type type,
> {
> sa_family_t af = ((const struct sockaddr *)sa)->sa_family;
> union epoll_ref ref = { .type = type, .data = data };
> + bool freebind = false;
> struct epoll_event ev;
> int fd, y = 1, ret;
> uint8_t proto;
> @@ -61,8 +62,11 @@ int sock_l4_sa(const struct ctx *c, enum epoll_type type,
> case EPOLL_TYPE_TCP_LISTEN:
> proto = IPPROTO_TCP;
> socktype = SOCK_STREAM | SOCK_NONBLOCK;
> + freebind = c->freebind;
> break;
> case EPOLL_TYPE_UDP_LISTEN:
> + freebind = c->freebind;
> + /* fallthrough */
> case EPOLL_TYPE_UDP_REPLY:
> proto = IPPROTO_UDP;
> socktype = SOCK_DGRAM | SOCK_NONBLOCK;
> @@ -127,6 +131,17 @@ int sock_l4_sa(const struct ctx *c, enum epoll_type type,
> }
> }
>
> + if (freebind) {
> + int level = af == AF_INET ? IPPROTO_IP : IPPROTO_IPV6;
> + int opt = af == AF_INET ? IP_FREEBIND : IPV6_FREEBIND;
> +
> + if (setsockopt(fd, level, opt, &y, sizeof(y))) {
> + err_perror("Failed to set %s on socket %i",
Indentation makes it look like err_perror() is part of the condition
(it should be one tab instead of spaces).
> + af == AF_INET ? "IP_FREEBIND" : "IPV6_FREEBIND",
> + fd);
> + }
> + }
> +
> if (bind(fd, sa, sl) < 0) {
> /* We'll fail to bind to low ports if we don't have enough
> * capabilities, and we'll fail to bind on already bound ports,
--
Stefano
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] conf: Add command line switch to enable IP_FREEBIND socket option
2024-10-02 7:16 ` Stefano Brivio
@ 2024-10-03 3:25 ` David Gibson
0 siblings, 0 replies; 3+ messages in thread
From: David Gibson @ 2024-10-03 3:25 UTC (permalink / raw)
To: Stefano Brivio; +Cc: passt-dev
[-- Attachment #1: Type: text/plain, Size: 5615 bytes --]
On Wed, Oct 02, 2024 at 09:16:52AM +0200, Stefano Brivio wrote:
> On Wed, 2 Oct 2024 14:47:16 +1000
> David Gibson <david@gibson.dropbear.id.au> wrote:
>
> > In a couple of recent reports, we've seen that it can be useful for pasta
> > to forward ports from addresses which are not currently configured on the
> > host, but might be in future. That can be done with the sysctl
> > net.ipv4.ip_nonlocal_bind, but that does require CAP_NET_ADMIN to set in
> > the first place. We can allow the same thing on a per-socket basis with
> > the IP_FREEBIND (or IPV6_FREEBIND) socket option.
> >
> > Add a --freebind command line argument to enable this socket option on
> > all listening sockets.
> >
> > Link: https://bugs.passt.top/show_bug.cgi?id=101
> >
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > ---
> > conf.c | 2 ++
> > passt.1 | 6 ++++++
> > passt.h | 1 +
> > util.c | 15 +++++++++++++++
> > 4 files changed, 24 insertions(+)
> >
> > diff --git a/conf.c b/conf.c
> > index 6e62510..84aa89d 100644
> > --- a/conf.c
> > +++ b/conf.c
> > @@ -836,6 +836,7 @@ static void usage(const char *name, FILE *f, int status)
> > " --no-ndp Disable NDP responses\n"
> > " --no-dhcpv6 Disable DHCPv6 server\n"
> > " --no-ra Disable router advertisements\n"
> > + " --freebind Allow forwarding from any address\n"
>
> I think "from any address" might be a bit ambiguous, because it could
> also be read as "Allow forwarding traffic coming from any address",
> which is allowed regardless.
Good point.
> What about:
>
> " --freebind Allow any address for forwarding\n"
>
> ?
Not sure that's notably better, though. I've gone with "Bind to any
address for forwarding".
> > " --no-map-gw Don't map gateway address to host\n"
> > " -4, --ipv4-only Enable IPv4 operation only\n"
> > " -6, --ipv6-only Enable IPv6 operation only\n");
> > @@ -1255,6 +1256,7 @@ void conf(struct ctx *c, int argc, char **argv)
> > {"no-dhcpv6", no_argument, &c->no_dhcpv6, 1 },
> > {"no-ndp", no_argument, &c->no_ndp, 1 },
> > {"no-ra", no_argument, &c->no_ra, 1 },
> > + {"freebind", no_argument, &c->freebind, 1 },
> > {"no-map-gw", no_argument, &no_map_gw, 1 },
> > {"ipv4-only", no_argument, NULL, '4' },
> > {"ipv6-only", no_argument, NULL, '6' },
> > diff --git a/passt.1 b/passt.1
> > index 79d134d..a2547f8 100644
> > --- a/passt.1
> > +++ b/passt.1
> > @@ -327,6 +327,12 @@ namespace will be silently dropped.
> > Disable Router Advertisements. Router Solicitations coming from guest or target
> > namespace will be ignored.
> >
> > +.TP
> > +.BR \-\-freebind
> > +Allow forwarding from addresses which are not configured on the host,
>
> Same here, it could also be read as "Allow forwarding traffic coming
> from addresses ...".
>
> Perhaps:
>
> Allow binding to addresses which are not configured on the host (but
> might be in the future) for port forwarding.
>
> ?
I've done a bit of rewording of this.
> > +but might be in future. This enables the \fBIP_FREEBIND\fR or
> > +\fBIPB6_FREEBIND\fR option on listening sockets.
> > +
> > .TP
> > .BR \-\-map-host-loopback " " \fIaddr
> > Translate \fIaddr\fR to refer to the host. Packets from the guest to
> > diff --git a/passt.h b/passt.h
> > index 031c9b6..e00049e 100644
> > --- a/passt.h
> > +++ b/passt.h
> > @@ -284,6 +284,7 @@ struct ctx {
> > int no_dhcpv6;
> > int no_ndp;
> > int no_ra;
> > + int freebind;
>
> Missing update to struct comment.
Dangit, thought I'd done that after missing it on the last series.
> >
> > int low_wmem;
> > int low_rmem;
> > diff --git a/util.c b/util.c
> > index ebd93ed..96e3de8 100644
> > --- a/util.c
> > +++ b/util.c
> > @@ -52,6 +52,7 @@ int sock_l4_sa(const struct ctx *c, enum epoll_type type,
> > {
> > sa_family_t af = ((const struct sockaddr *)sa)->sa_family;
> > union epoll_ref ref = { .type = type, .data = data };
> > + bool freebind = false;
> > struct epoll_event ev;
> > int fd, y = 1, ret;
> > uint8_t proto;
> > @@ -61,8 +62,11 @@ int sock_l4_sa(const struct ctx *c, enum epoll_type type,
> > case EPOLL_TYPE_TCP_LISTEN:
> > proto = IPPROTO_TCP;
> > socktype = SOCK_STREAM | SOCK_NONBLOCK;
> > + freebind = c->freebind;
> > break;
> > case EPOLL_TYPE_UDP_LISTEN:
> > + freebind = c->freebind;
> > + /* fallthrough */
> > case EPOLL_TYPE_UDP_REPLY:
> > proto = IPPROTO_UDP;
> > socktype = SOCK_DGRAM | SOCK_NONBLOCK;
> > @@ -127,6 +131,17 @@ int sock_l4_sa(const struct ctx *c, enum epoll_type type,
> > }
> > }
> >
> > + if (freebind) {
> > + int level = af == AF_INET ? IPPROTO_IP : IPPROTO_IPV6;
> > + int opt = af == AF_INET ? IP_FREEBIND : IPV6_FREEBIND;
> > +
> > + if (setsockopt(fd, level, opt, &y, sizeof(y))) {
> > + err_perror("Failed to set %s on socket %i",
>
> Indentation makes it look like err_perror() is part of the condition
> (it should be one tab instead of spaces).
Oops, corrected.
> > + af == AF_INET ? "IP_FREEBIND" : "IPV6_FREEBIND",
> > + fd);
> > + }
> > + }
> > +
> > if (bind(fd, sa, sl) < 0) {
> > /* We'll fail to bind to low ports if we don't have enough
> > * capabilities, and we'll fail to bind on already bound ports,
>
--
David Gibson (he or they) | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you, not the other way
| around.
http://www.ozlabs.org/~dgibson
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^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2024-10-03 3:42 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2024-10-02 4:47 [PATCH] conf: Add command line switch to enable IP_FREEBIND socket option David Gibson
2024-10-02 7:16 ` Stefano Brivio
2024-10-03 3:25 ` David Gibson
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