diff options
| author | Stanislav Fomichev <sdf@fomichev.me> | 2024-07-26 15:20:48 -0700 |
|---|---|---|
| committer | Martin KaFai Lau <martin.lau@kernel.org> | 2024-07-30 15:14:18 -0700 |
| commit | 32654bbd6313b4cfc82297e6634fa9725c3c900f (patch) | |
| tree | 74fb55e733a0901bf6a625a3e02cfe9445c8fced /net/xdp | |
| parent | 1cbe8143fd2f588031a5f157d15ae15ce12215e2 (diff) | |
xsk: Try to make xdp_umem_reg extension a bit more future-proof
We recently found out that extending xsk_umem_reg might be a bit
complicated due to not enforcing padding to be zero [0]. Add
a couple of things to make it less error-prone:
1. Remove xdp_umem_reg_v2 since its sizeof is the same as xdp_umem_reg
2. Add BUILD_BUG_ON that checks that the size of xdp_umem_reg_v1 is less
than xdp_umem_reg; presumably, when we get to v2, there is gonna
be a similar line to enforce that sizeof(v2) > sizeof(v1)
3. Add BUILD_BUG_ON to make sure the last field plus its size matches
the overall struct size. The intent is to demonstrate that we don't
have any lingering padding.
0: https://lore.kernel.org/bpf/ZqI29QE+5JnkdPmE@boxer/T/#me03113f7c2458fd08f3c4114a7a9472ac3646c98
Reported-by: Julian Schindel <mail@arctic-alpaca.de>
Cc: Magnus Karlsson <magnus.karlsson@gmail.com>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://lore.kernel.org/r/20240726222048.1397869-1-sdf@fomichev.me
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Diffstat (limited to 'net/xdp')
| -rw-r--r-- | net/xdp/xsk.c | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index 7e16336044b2..1140b2a120ca 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -1320,14 +1320,6 @@ struct xdp_umem_reg_v1 { __u32 headroom; }; -struct xdp_umem_reg_v2 { - __u64 addr; /* Start of packet data area */ - __u64 len; /* Length of packet data area */ - __u32 chunk_size; - __u32 headroom; - __u32 flags; -}; - static int xsk_setsockopt(struct socket *sock, int level, int optname, sockptr_t optval, unsigned int optlen) { @@ -1371,10 +1363,19 @@ static int xsk_setsockopt(struct socket *sock, int level, int optname, if (optlen < sizeof(struct xdp_umem_reg_v1)) return -EINVAL; - else if (optlen < sizeof(struct xdp_umem_reg_v2)) - mr_size = sizeof(struct xdp_umem_reg_v1); else if (optlen < sizeof(mr)) - mr_size = sizeof(struct xdp_umem_reg_v2); + mr_size = sizeof(struct xdp_umem_reg_v1); + + BUILD_BUG_ON(sizeof(struct xdp_umem_reg_v1) >= sizeof(struct xdp_umem_reg)); + + /* Make sure the last field of the struct doesn't have + * uninitialized padding. All padding has to be explicit + * and has to be set to zero by the userspace to make + * struct xdp_umem_reg extensible in the future. + */ + BUILD_BUG_ON(offsetof(struct xdp_umem_reg, tx_metadata_len) + + sizeof_field(struct xdp_umem_reg, tx_metadata_len) != + sizeof(struct xdp_umem_reg)); if (copy_from_sockptr(&mr, optval, mr_size)) return -EFAULT; |