diff options
| author | Timo Völker <timo.voelker@fh-muenster.de> | 2026-08-16 18:31:33 +0000 |
|---|---|---|
| committer | Michael Tuexen <tuexen@FreeBSD.org> | 2026-08-16 18:38:36 +0000 |
| commit | f343f036c780cfd8e7f243b7708d96b006a257d7 (patch) | |
| tree | 15ffc32cd06d7edd3eeabbf2a22f365f259f7acc | |
| parent | 550db3d6f502946f6cf01eeb34f53e70395ddc6f (diff) | |
epair: allow disabling receive checksum offloading
Allow disabling RXCSUM and RXCSUM6 on an epair interface. If disabled,
epair unsets the mbuf flags that indicate a valid checksum when
transferring a packet from one epair end to the other. This gives a
user in a jail the power to control whether the user wants to use the
result of a previous validation (by a physical interface) or not.
Reviewed by: kp, tuexen
MFC after: 1 month
MFC to: stable/15
Differential Revision: https://reviews.freebsd.org/D58786
| -rw-r--r-- | share/man/man4/epair.4 | 10 | ||||
| -rw-r--r-- | sys/net/if_epair.c | 24 |
2 files changed, 23 insertions, 11 deletions
diff --git a/share/man/man4/epair.4 b/share/man/man4/epair.4 index ba42106d45f8..f28f68bdfc19 100644 --- a/share/man/man4/epair.4 +++ b/share/man/man4/epair.4 @@ -25,7 +25,7 @@ .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" -.Dd January 30, 2026 +.Dd August 16, 2026 .Dt EPAIR 4 .Os .Sh NAME @@ -111,8 +111,12 @@ configured on top of it. .Pp The .Nm -has RXCSUM and RXCSUM6 enabled because it may receive a packet where the -checksum has already been validated by a physical interface. +supports RXCSUM and RXCSUM6 but does not validate a checksum. +In case an interface previously validated the checksum, +.Nm +leaves the flags set that indicate a valid checksum if RXCSUM and RXCSUM6 are +enabled or unsets these flags if RXCSUM and RXCSUM6 are disabled. +Note that RXCSUM and RXCSUM6 can only be enabled or disabled as a pair. .Pp The .Nm diff --git a/sys/net/if_epair.c b/sys/net/if_epair.c index 5addd43b6190..c3354bc76e64 100644 --- a/sys/net/if_epair.c +++ b/sys/net/if_epair.c @@ -242,6 +242,9 @@ epair_prepare_mbuf(struct mbuf *m, struct ifnet *src_ifp) epair_clear_mbuf(m); if_setrcvif(m, src_ifp); M_SETFIB(m, src_ifp->if_fib); + if ((if_getcapenable(src_ifp) & IFCAP_RXCSUM) == 0) + m->m_pkthdr.csum_flags &= ~(CSUM_L3_CALC | CSUM_L3_VALID | + CSUM_L4_CALC | CSUM_L4_VALID); MPASS(m->m_nextpkt == NULL); MPASS((m->m_pkthdr.csum_flags & CSUM_SND_TAG) == 0); @@ -455,7 +458,7 @@ epair_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data) { struct epair_softc *sc; struct ifreq *ifr; - int error; + int error, cap; ifr = (struct ifreq *)data; switch (cmd) { @@ -484,14 +487,19 @@ epair_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data) break; case SIOCSIFCAP: /* - * Enable/disable capabilities as requested, besides - * IFCAP_RXCSUM(_IPV6), which always remain enabled. - * Incoming packets may have the mbuf flag CSUM_DATA_VALID set. - * Without IFCAP_RXCSUM(_IPV6), this flag would have to be - * removed, which does not seem helpful. + * Enable/disable capabilities as requested, but treat + * IFCAP_RXCSUM and IFCAP_RXCSUM_IPV6 special as they can only + * be set or unset as pair. */ - ifp->if_capenable = ifr->ifr_reqcap | IFCAP_RXCSUM | - IFCAP_RXCSUM_IPV6; + cap = ifr->ifr_reqcap; + if (((cap & IFCAP_RXCSUM) == 0) != + ((cap & IFCAP_RXCSUM_IPV6) == 0)) { + if ((ifp->if_capenable & IFCAP_RXCSUM) == 0) + cap |= (IFCAP_RXCSUM | IFCAP_RXCSUM_IPV6); + else + cap &= ~(IFCAP_RXCSUM | IFCAP_RXCSUM_IPV6); + } + ifp->if_capenable = cap; epair_caps_changed(ifp); VLAN_CAPABILITIES(ifp); /* |