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| author | Sabrina Dubroca <sd@queasysnail.net> | 2019-03-25 14:30:00 +0100 |
|---|---|---|
| committer | Steffen Klassert <steffen.klassert@secunet.com> | 2019-03-26 08:39:30 +0100 |
| commit | 8dfb4eba4100e7cdd161a8baef2d8d61b7a7e62e (patch) | |
| tree | 47012e3eeefbbbaf24cd5908f2e55b7335e52327 /net/ipv4/esp4.c | |
| parent | dbb2483b2a46fbaf833cfb5deb5ed9cace9c7399 (diff) | |
| download | lwn-8dfb4eba4100e7cdd161a8baef2d8d61b7a7e62e.tar.gz lwn-8dfb4eba4100e7cdd161a8baef2d8d61b7a7e62e.zip | |
esp4: add length check for UDP encapsulation
esp_output_udp_encap can produce a length that doesn't fit in the 16
bits of a UDP header's length field. In that case, we'll send a
fragmented packet whose length is larger than IP_MAX_MTU (resulting in
"Oversized IP packet" warnings on receive) and with a bogus UDP
length.
To prevent this, add a length check to esp_output_udp_encap and return
-EMSGSIZE on failure.
This seems to be older than git history.
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Diffstat (limited to 'net/ipv4/esp4.c')
| -rw-r--r-- | net/ipv4/esp4.c | 20 |
1 files changed, 15 insertions, 5 deletions
diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c index 10e809b296ec..fb065a8937ea 100644 --- a/net/ipv4/esp4.c +++ b/net/ipv4/esp4.c @@ -226,7 +226,7 @@ static void esp_output_fill_trailer(u8 *tail, int tfclen, int plen, __u8 proto) tail[plen - 1] = proto; } -static void esp_output_udp_encap(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp) +static int esp_output_udp_encap(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp) { int encap_type; struct udphdr *uh; @@ -234,6 +234,7 @@ static void esp_output_udp_encap(struct xfrm_state *x, struct sk_buff *skb, stru __be16 sport, dport; struct xfrm_encap_tmpl *encap = x->encap; struct ip_esp_hdr *esph = esp->esph; + unsigned int len; spin_lock_bh(&x->lock); sport = encap->encap_sport; @@ -241,11 +242,14 @@ static void esp_output_udp_encap(struct xfrm_state *x, struct sk_buff *skb, stru encap_type = encap->encap_type; spin_unlock_bh(&x->lock); + len = skb->len + esp->tailen - skb_transport_offset(skb); + if (len + sizeof(struct iphdr) >= IP_MAX_MTU) + return -EMSGSIZE; + uh = (struct udphdr *)esph; uh->source = sport; uh->dest = dport; - uh->len = htons(skb->len + esp->tailen - - skb_transport_offset(skb)); + uh->len = htons(len); uh->check = 0; switch (encap_type) { @@ -262,6 +266,8 @@ static void esp_output_udp_encap(struct xfrm_state *x, struct sk_buff *skb, stru *skb_mac_header(skb) = IPPROTO_UDP; esp->esph = esph; + + return 0; } int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp) @@ -275,8 +281,12 @@ int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info * int tailen = esp->tailen; /* this is non-NULL only with UDP Encapsulation */ - if (x->encap) - esp_output_udp_encap(x, skb, esp); + if (x->encap) { + int err = esp_output_udp_encap(x, skb, esp); + + if (err < 0) + return err; + } if (!skb_cloned(skb)) { if (tailen <= skb_tailroom(skb)) { |