From bfda0d0f09666e2476c9abd0280c4b9fa82b968c Mon Sep 17 00:00:00 2001 From: Thomas Haller Date: Wed, 19 Dec 2018 10:05:37 +0100 Subject: [PATCH] dhcp: don't enforce hardware address length for sd_dhcp_client_set_client_id() sd_dhcp_client_set_client_id() is the only API for setting a raw client-id. All other setters are more restricted and only allow to set a type 255 DUID. Also, dhcp4_set_client_identifier() is the only caller, which already does: r = sd_dhcp_client_set_client_id(link->dhcp_client, ARPHRD_ETHER, (const uint8_t *) &link->mac, sizeof(link->mac)); and hence ensures that the data length is indeed ETH_ALEN. Drop additional input validation from sd_dhcp_client_set_client_id(). The client-id is an opaque blob, and if a caller wishes to set type 1 (ethernet) or type 32 (infiniband) with unexpected address length, it should be allowed. The actual client-id is not relevant to the DHCP client, and it's the responsibility of the caller to generate a suitable client-id. For example, in NetworkManager you can configure all the bytes of the client-id, including such _invalid_ settings. I think it makes sense, to allow the user to fully configure the identifier. Even if such configuration would be rejected, it would be the responsibility of the higher layers (including a sensible error message to the user) and not fail later during sd_dhcp_client_set_client_id(). Still log a debug message if the length is unexpected. --- src/libsystemd-network/sd-dhcp-client.c | 29 +++++++++++------------------ 1 file changed, 11 insertions(+), 18 deletions(-) diff --git a/src/libsystemd-network/sd-dhcp-client.c b/src/libsystemd-network/sd-dhcp-client.c index ff7f547..f39af0d 100644 --- a/src/libsystemd-network/sd-dhcp-client.c +++ b/src/libsystemd-network/sd-dhcp-client.c @@ -300,29 +300,22 @@ int sd_dhcp_client_set_client_id( assert_return(data, -EINVAL); assert_return(data_len > 0 && data_len <= MAX_CLIENT_ID_LEN, -EINVAL); - switch (type) { - - case ARPHRD_ETHER: - if (data_len != ETH_ALEN) - return -EINVAL; - break; - - case ARPHRD_INFINIBAND: - /* Infiniband addresses are 20 bytes (INFINIBAND_ALEN), however only - * the last 8 bytes are stable and suitable for putting into the client-id. */ - if (data_len != 8) - return -EINVAL; - break; - - default: - break; - } - if (client->client_id_len == data_len + sizeof(client->client_id.type) && client->client_id.type == type && memcmp(&client->client_id.raw.data, data, data_len) == 0) return 0; + /* For hardware types, log debug message about unexpected data length. + * + * Note that infiniband's INFINIBAND_ALEN is 20 bytes long, but only + * last last 8 bytes of the address are stable and suitable to put into + * the client-id. The caller is advised to account for that. */ + if ((type == ARPHRD_ETHER && data_len != ETH_ALEN) || + (type == ARPHRD_INFINIBAND && data_len != 8)) + log_dhcp_client(client, "Changing client ID to hardware type %u with " + "unexpected address length %zu", + type, data_len); + if (!IN_SET(client->state, DHCP_STATE_INIT, DHCP_STATE_STOPPED)) { log_dhcp_client(client, "Changing client ID on running DHCP " "client, restarting"); -- 2.7.4