diff options
| author | Pablo Neira Ayuso <pablo@netfilter.org> | 2024-05-07 01:11:47 +0200 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2024-05-07 01:35:55 +0200 |
| commit | b6fc0956ac532d1b35f6f517c083603b5e150b0d (patch) | |
| tree | d12fb58ece454decaee6637a6a1a62166db9510a /include/net/gtp.h | |
| parent | 353f5ffbc63b532aa0c92a7635e84bd53d04644e (diff) | |
gtp: properly parse extension headers
Currently GTP packets are dropped if the next extension field is set to
non-zero value, but this are valid GTP packets.
TS 29.281 provides a longer header format, which is defined as struct
gtp1_header_long. Such long header format is used if any of the S, PN, E
flags is set.
This long header is 4 bytes longer than struct gtp1_header, plus
variable length (optional) extension headers. The next extension header
field is zero is no extension header is provided.
The extension header is composed of a length field which includes total
number of 4 byte words including the extension header itself (1 byte),
payload (variable length) and next type (1 byte). The extension header
size and its payload is aligned to 4 bytes.
A GTP packet might come with a chain extensions headers, which makes it
slightly cumbersome to parse because the extension next header field
comes at the end of the extension header, and there is a need to check
if this field becomes zero to stop the extension header parser.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'include/net/gtp.h')
| -rw-r--r-- | include/net/gtp.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/include/net/gtp.h b/include/net/gtp.h index 2a503f035d18..c0253c8702d0 100644 --- a/include/net/gtp.h +++ b/include/net/gtp.h @@ -78,4 +78,9 @@ static inline bool netif_is_gtp(const struct net_device *dev) #define GTP1_F_EXTHDR 0x04 #define GTP1_F_MASK 0x07 +struct gtp_ext_hdr { + __u8 len; + __u8 data[]; +}; + #endif |