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if_ovpn: remove incorrect rounding up of packet sizes

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The ciphers used by OpenVPN (DCO) do not require data to be block-sized.
Do not round up to AES_BLOCK_LEN, as this can lead to issues with
fragmented packets.

Reported by:	Gert Doering <gert@greenie.muc.de>
Sponsored by:	Rubicon Communications, LLC ("Netgate")
This commit is contained in:
Kristof Provost 2022-09-21 12:17:34 +02:00
parent 8ea48fc59e
commit 9dfbbc919f
1 changed files with 3 additions and 12 deletions
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15
sys/net/if_ovpn.c
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@ -1557,8 +1557,6 @@ ovpn_decrypt_rx_cb(struct cryptop *crp)
return (0);
}
static uint8_t EMPTY_BUFFER[AES_BLOCK_LEN];
static int
ovpn_get_af(struct mbuf *m)
{
@ -1729,7 +1727,7 @@ ovpn_transmit_to_peer(struct ifnet *ifp, struct mbuf *m,
struct ovpn_softc *sc;
struct cryptop *crp;
uint32_t af, seq;
size_t len, real_len, ovpn_hdr_len;
size_t len, ovpn_hdr_len;
int tunnel_len;
int ret;
@ -1752,19 +1750,12 @@ ovpn_transmit_to_peer(struct ifnet *ifp, struct mbuf *m,
if (af != 0)
BPF_MTAP2(ifp, &af, sizeof(af), m);
real_len = len = m->m_pkthdr.len;
MPASS(real_len <= ifp->if_mtu);
len = m->m_pkthdr.len;
MPASS(len <= ifp->if_mtu);
ovpn_hdr_len = sizeof(struct ovpn_wire_header);
if (key->encrypt->cipher == OVPN_CIPHER_ALG_NONE)
ovpn_hdr_len -= 16; /* No auth tag. */
else {
/* Round up the len to a multiple of our block size. */
len = roundup2(real_len, AES_BLOCK_LEN);
/* Now extend the mbuf. */
m_append(m, len - real_len, EMPTY_BUFFER);
}
M_PREPEND(m, ovpn_hdr_len, M_NOWAIT);
if (m == NULL) {