On 21 Aug 2024, at 21:48, Ilya Maximets wrote:
> On 8/16/24 13:02, Eelco Chaudron wrote:
>> Updated the dpif_nl_exec_monitor.py utility to also optionally monitor
>> the other DPIF netlink operations, i.e., DPIF_OP_FLOW_PUT,
>> DPIF_OP_FLOW_DEL and DPIF_OP_FLOW_GET
>
> Should the script be renamed then?
I was in doubt, dpif_nl_op_monitor.py was my idea. If you feel like we should,
let me know and I do it in next rev.
> BTW, get_ovs_action_attr_str() is outdated. Should be a separate fix though.
Good catch, I will add a patch.
>
>>
>> Signed-off-by: Eelco Chaudron <echau...@redhat.com>
>> ---
>> .../usdt-scripts/dpif_nl_exec_monitor.py | 276 +++++++++++++-----
>> 1 file changed, 197 insertions(+), 79 deletions(-)
>>
>> diff --git a/utilities/usdt-scripts/dpif_nl_exec_monitor.py
>> b/utilities/usdt-scripts/dpif_nl_exec_monitor.py
>> index 0a9ff8123..b860d4359 100755
>> --- a/utilities/usdt-scripts/dpif_nl_exec_monitor.py
>> +++ b/utilities/usdt-scripts/dpif_nl_exec_monitor.py
>> @@ -19,7 +19,8 @@
>> # dpif_nl_exec_monitor.py uses the dpif_netlink_operate__:op_flow_execute
>> USDT
>> # probe to receive all DPIF_OP_EXECUTE operations that are queued for
>> # transmission over the netlink socket. It will do some basic decoding, and
>> if
>> -# requested a packet dump.
>> +# requested a packet dump. Note that there are also options to obtain
>> +# additional information for the DPIF_OP_FLOW_* operations.
>> #
>> # Here is an example:
>> #
>> @@ -75,31 +76,9 @@
>> # seq = 0xc
>> #
>> # The example above dumps the full netlink and packet decode. However
>> options
>> -# exist to disable this. Here is the full list of supported options:
>> -#
>> -# usage: dpif_nl_exec_monitor.py [-h] [--buffer-page-count NUMBER] [-D
>> [DEBUG]]
>> -# [-d {none,hex,decode}] [-n
>> {none,hex,nlraw}]
>> -# [-p VSWITCHD_PID] [-s [64-2048]]
>> -# [-w PCAP_FILE]
>> -#
>> -# optional arguments:
>> -# -h, --help show this help message and exit
>> -# --buffer-page-count NUMBER
>> -# Number of BPF ring buffer pages, default 1024
>> -# -D [DEBUG], --debug [DEBUG]
>> -# Enable eBPF debugging
>> -# -d {none,hex,decode}, --packet-decode {none,hex,decode}
>> -# Display packet content in selected mode, default
>> none
>> -# -n {none,hex,nlraw}, --nlmsg-decode {none,hex,nlraw}
>> -# Display netlink message content in selected mode,
>> -# default nlraw
>> -# -p VSWITCHD_PID, --pid VSWITCHD_PID
>> -# ovs-vswitch's PID
>> -# -s [64-2048], --nlmsg-size [64-2048]
>> -# Set maximum netlink message size to capture,
>> default
>> -# 512
>> -# -w PCAP_FILE, --pcap PCAP_FILE
>> -# Write upcall packets to specified pcap file
>> +# exist to disable this. For a complete list of options, please use the
>> +# '--help' or '-h' argument.
>> +#
>>
>> from bcc import BPF, USDT, USDTException
>> from os.path import exists
>> @@ -142,12 +121,10 @@ struct ofpbuf {
>> BPF_RINGBUF_OUTPUT(events, <BUFFER_PAGE_CNT>);
>> BPF_TABLE("percpu_array", uint32_t, uint64_t, dropcnt, 1);
>>
>> -int trace__op_flow_execute(struct pt_regs *ctx) {
>> - struct ofpbuf nlbuf;
>> +static int trace_event(struct ofpbuf *nlbuf)
>> +{
>> uint32_t size;
>>
>> - bpf_usdt_readarg_p(5, ctx, &nlbuf, sizeof(nlbuf));
>> -
>> struct event_t *event = events.ringbuf_reserve(sizeof(struct event_t));
>> if (!event) {
>> uint32_t type = 0;
>> @@ -163,17 +140,51 @@ int trace__op_flow_execute(struct pt_regs *ctx) {
>> event->pid = bpf_get_current_pid_tgid();
>> bpf_get_current_comm(&event->comm, sizeof(event->comm));
>>
>> - event->nl_size = nlbuf.size;
>> + event->nl_size = nlbuf->size;
>> if (event->nl_size > MAX_NLMSG)
>> size = MAX_NLMSG;
>> else
>> size = event->nl_size;
>>
>> - bpf_probe_read(&event->nl_msg, size, nlbuf.data);
>> + bpf_probe_read(&event->nl_msg, size, nlbuf->data);
>>
>> events.ringbuf_submit(event, 0);
>> return 0;
>> +}
>> +
>> +int trace__op_execute(struct pt_regs *ctx) {
>> + struct ofpbuf nlbuf;
>> +
>> + bpf_usdt_readarg_p(5, ctx, &nlbuf, sizeof(nlbuf));
>> + return trace_event(&nlbuf);
>> +};
>> +
>> +#if <ENABLE_OP_FLOW_PUT>
>> +int trace__op_flow_put(struct pt_regs *ctx) {
>> + struct ofpbuf nlbuf;
>> +
>> + bpf_usdt_readarg_p(4, ctx, &nlbuf, sizeof(nlbuf));
>> + return trace_event(&nlbuf);
>> +};
>> +#endif
>> +
>> +#if <ENABLE_OP_FLOW_DEL>
>> +int trace__op_flow_del(struct pt_regs *ctx) {
>> + struct ofpbuf nlbuf;
>> +
>> + bpf_usdt_readarg_p(4, ctx, &nlbuf, sizeof(nlbuf));
>> + return trace_event(&nlbuf);
>> };
>> +#endif
>> +
>> +#if <ENABLE_OP_FLOW_GET>
>> +int trace__op_flow_get(struct pt_regs *ctx) {
>> + struct ofpbuf nlbuf;
>> +
>> + bpf_usdt_readarg_p(4, ctx, &nlbuf, sizeof(nlbuf));
>> + return trace_event(&nlbuf);
>> +};
>> +#endif
>> """
>>
>>
>> @@ -182,21 +193,24 @@ int trace__op_flow_execute(struct pt_regs *ctx) {
>> #
>> def print_event(ctx, data, size):
>> event = b["events"].event(data)
>> - print("{:<18.9f} {:<4} {:<16} {:<10} {:<10}".
>> +
>> + if event.nl_size < options.nlmsg_size:
>> + nl_size = event.nl_size
>> + else:
>> + nl_size = options.nlmsg_size
>> +
>> + print("{:<18.9f} {:<4} {:<16} {:<10} {:<10} {}".
>> format(event.ts / 1000000000,
>> event.cpu,
>> event.comm.decode("utf-8"),
>> event.pid,
>> - event.nl_size))
>> + event.nl_size,
>> + get_ovs_dpif_op_str(get_cmd_type_from_nlm(
>> + bytes(event.nl_msg)[:nl_size]))))
>>
>> #
>> # Dumping the netlink message data if requested.
>> #
>> - if event.nl_size < options.nlmsg_size:
>> - nl_size = event.nl_size
>> - else:
>> - nl_size = options.nlmsg_size
>> -
>> if options.nlmsg_decode == "hex":
>> #
>> # Abuse scapy's hex dump to dump flow key
>> @@ -306,6 +320,16 @@ def decode_nlm_tlvs(tlvs, header=None, indent=4,
>> dump=True,
>> return result
>>
>>
>> +#
>> +# get_op_type_from_nlm()
>
> Copy-paste error?
Nope, changed the name, will fix.
>> +#
>> +def get_cmd_type_from_nlm(nlm):
>> + if len(nlm) < 17:
>> + return -1
>> +
>> + return struct.unpack("=B", nlm[16:17])[0]
>
> Lots of magic numbers here, can we use some enum/structure?
> Or at least, exaplin what is going on here in the comment.
ACK, will do.
>> +
>> +
>> #
>> # decode_nlm()
>> #
>> @@ -325,9 +349,11 @@ def decode_nlm(msg, indent=4, dump=True):
>> #
>> # Decode 'struct genlmsghdr'
>> #
>> + cmd, version, reserved = struct.unpack("=BBH", msg[:4])
>> +
>> if dump:
>> - print("{}genlmsghdr: cmd = {}, version = {}, reserver = {}".format(
>> - " " * indent, *struct.unpack("=BBH", msg[:4])))
>> + print("{}genlmsghdr: cmd = {}, version = {}, reserved = {}".format(
>> + " " * indent, get_ovs_dpif_op_str(cmd), version, reserved))
>>
>> msg = msg[4:]
>>
>> @@ -343,42 +369,94 @@ def decode_nlm(msg, indent=4, dump=True):
>> #
>> # Decode TLVs
>> #
>> - nl_attr_tree = {
>> - "OVS_PACKET_ATTR_KEY": {
>> - "header": "> Decode OVS_KEY_ATTR_* TLVs:",
>> - "indent": 4,
>> - "attr_str_func": get_ovs_key_attr_str,
>> - "decode_tree": None,
>> - },
>> - "OVS_PACKET_ATTR_ACTIONS": {
>> - "header": "> Decode OVS_ACTION_ATTR_* TLVs:",
>> - "indent": 4,
>> - "attr_str_func": get_ovs_action_attr_str,
>> - "decode_tree": {
>> - "OVS_ACTION_ATTR_SET": {
>> - "header": "> Decode OVS_KEY_ATTR_* TLVs:",
>> - "indent": 4,
>> - "attr_str_func": get_ovs_key_attr_str,
>> - "decode_tree": {
>> - "OVS_KEY_ATTR_TUNNEL": {
>> - "header": "> Decode OVS_TUNNEL_KEY_ATTR_*
>> TLVs:",
>> - "indent": 4,
>> - "attr_str_func": get_ovs_tunnel_key_attr_str,
>> - "decode_tree": None,
>> - },
>> + nl_key_attr = {
>> + "header": "> Decode OVS_KEY_ATTR_* TLVs:",
>> + "indent": 4,
>> + "attr_str_func": get_ovs_key_attr_str,
>> + "decode_tree": {
>> + "OVS_KEY_ATTR_ENCAP": {
>> + "header": "> Decode OVS_KEY_ATTR_* TLVs:",
>> + "indent": 4,
>> + "attr_str_func": get_ovs_key_attr_str,
>> + "decode_tree": {
>> + "OVS_KEY_ATTR_ENCAP": {
>> + "header": "> Decode OVS_KEY_ATTR_* TLVs:",
>> + "indent": 4,
>> + "attr_str_func": get_ovs_key_attr_str,
>> + "decode_tree": None,
>> + },
>> + },
>> + },
>> + }
>> + }
>> +
>> + nl_action_attr = {
>> + "header": "> Decode OVS_ACTION_ATTR_* TLVs:",
>> + "indent": 4,
>> + "attr_str_func": get_ovs_action_attr_str,
>> + "decode_tree": {
>> + "OVS_ACTION_ATTR_SET": {
>> + "header": "> Decode OVS_KEY_ATTR_* TLVs:",
>> + "indent": 4,
>> + "attr_str_func": get_ovs_key_attr_str,
>> + "decode_tree": {
>> + "OVS_KEY_ATTR_TUNNEL": {
>> + "header": "> Decode OVS_TUNNEL_KEY_ATTR_* TLVs:",
>> + "indent": 4,
>> + "attr_str_func": get_ovs_tunnel_key_attr_str,
>> + "decode_tree": None,
>> },
>> },
>> },
>> },
>> }
>>
>> - result = decode_nlm_tlvs(msg, indent=indent + 2, dump=dump,
>> - header="> Decode OVS_PACKET_ATTR_* TLVs:",
>> - attr_to_str_func=get_ovs_pkt_attr_str,
>> - decode_tree=nl_attr_tree)
>> + nl_attr_tree_exec = {
>> + "OVS_PACKET_ATTR_KEY": nl_key_attr,
>> + "OVS_PACKET_ATTR_ACTIONS": nl_action_attr,
>> + }
>> +
>> + nl_attr_tree_put = {
>> + "OVS_FLOW_ATTR_KEY": nl_key_attr,
>> + "OVS_FLOW_ATTR_MASK": nl_key_attr,
>> + "OVS_FLOW_ATTR_ACTIONS": nl_action_attr,
>> + }
>> +
>> + if cmd == 3:
>
> Magic number. Maybe use get_ovs_dpif_op_str() and compare the string?
Good idea.
>> + result = decode_nlm_tlvs(msg, indent=indent + 2, dump=dump,
>> + header="> Decode OVS_PACKET_ATTR_* TLVs:",
>> + attr_to_str_func=get_ovs_pkt_attr_str,
>> + decode_tree=nl_attr_tree_exec)
>> + else:
>> + result = decode_nlm_tlvs(msg, indent=indent + 2, dump=dump,
>> + header="> Decode OVS_FLOW_ATTR_* TLVs:",
>> + attr_to_str_func=get_ovs_flow_attr_str,
>> + decode_tree=nl_attr_tree_put)
>> return result
>>
>>
>> +#
>> +# get_ovs_flow_attr_str()
>> +#
>> +def get_ovs_flow_attr_str(attr):
>> + ovs_flow_attr = ["OVS_FLOW_ATTR_UNSPEC",
>> + "OVS_FLOW_ATTR_KEY",
>> + "OVS_FLOW_ATTR_ACTIONS",
>> + "OVS_FLOW_ATTR_STATS",
>> + "OVS_FLOW_ATTR_TCP_FLAGS",
>> + "OVS_FLOW_ATTR_USED",
>> + "OVS_FLOW_ATTR_CLEAR",
>> + "OVS_FLOW_ATTR_MASK",
>> + "OVS_FLOW_ATTR_PROBE",
>> + "OVS_FLOW_ATTR_UFID",
>> + "OVS_FLOW_ATTR_UFID_FLAGS",
>> + "OVS_FLOW_ATTR_PAD"]
>> + if attr < 0 or attr >= len(ovs_flow_attr):
>> + return "<UNKNOWN:{}>".format(attr)
>> +
>> + return ovs_flow_attr[attr]
>> +
>> +
>> #
>> # get_ovs_pkt_attr_str()
>> #
>> @@ -505,6 +583,22 @@ def get_ovs_tunnel_key_attr_str(attr):
>> return ovs_tunnel_key_attr[attr]
>>
>>
>> +#
>> +# get_ovs_dpif_op_str()
>> +#
>> +def get_ovs_dpif_op_str(op):
>> + ovs_dpif_ops = ["DPIF_OP_UNSPEC",
>> + "DPIF_OP_FLOW_PUT",
>> + "DPIF_OP_FLOW_DEL",
>> + "DPIF_OP_EXECUTE",
>> + "DPIF_OP_FLOW_GET"]
>> +
>> + if op < 0 or op >= len(ovs_dpif_ops):
>> + return "<UNKNOWN:{}>".format(op)
>> +
>> + return ovs_dpif_ops[op]
>> +
>> +
>> #
>> # buffer_size_type()
>> #
>> @@ -564,8 +658,17 @@ def main():
>> help="Set maximum netlink message size to capture, "
>> "default 512", type=buffer_size_type, default=512,
>> metavar="[64-2048]")
>> + parser.add_argument("--trace-del-op",
>> + help="Monitor DPIF_OP_FLOW_DEL messages",
>> + action="store_true")
>> + parser.add_argument("--trace-get-op",
>> + help="Monitor DPIF_OP_FLOW_GET messages",
>> + action="store_true")
>> + parser.add_argument("--trace-put-op",
>> + help="Monitor DPIF_OP_FLOW_PUT messages",
>> + action="store_true")
>> parser.add_argument("-w", "--pcap", metavar="PCAP_FILE",
>> - help="Write upcall packets to specified pcap file",
>> + help="Write execute packets to specified pcap file",
>> type=str, default=None)
>>
>> options = parser.parse_args()
>> @@ -604,13 +707,21 @@ def main():
>> u = USDT(pid=int(options.pid))
>> try:
>> u.enable_probe(probe="dpif_netlink_operate__:op_flow_execute",
>> - fn_name="trace__op_flow_execute")
>> + fn_name="trace__op_execute")
>> + if options.trace_put_op:
>> + u.enable_probe(probe="dpif_netlink_operate__:op_flow_put",
>> + fn_name="trace__op_flow_put")
>> + if options.trace_del_op:
>> + u.enable_probe(probe="dpif_netlink_operate__:op_flow_del",
>> + fn_name="trace__op_flow_del")
>> + if options.trace_get_op:
>> + u.enable_probe(probe="dpif_netlink_operate__:op_flow_get",
>> + fn_name="trace__op_flow_get")
>> except USDTException as e:
>> - print("ERROR: {}"
>> - "ovs-vswitchd!".format(
>> - (re.sub("^", " " * 7, str(e),
>> flags=re.MULTILINE)).strip().
>> - replace("--with-dtrace or --enable-dtrace",
>> - "--enable-usdt-probes")))
>> + print("ERROR: {}".format(
>> + (re.sub("^", " " * 7, str(e), flags=re.MULTILINE)).strip().
>> + replace("--with-dtrace or --enable-dtrace",
>> + "--enable-usdt-probes")))
>> sys.exit(-1)
>>
>> #
>> @@ -625,15 +736,22 @@ def main():
>> source = source.replace("<BUFFER_PAGE_CNT>",
>> str(options.buffer_page_count))
>>
>> + source = source.replace("<ENABLE_OP_FLOW_DEL>",
>> + "1" if options.trace_del_op else "0")
>> + source = source.replace("<ENABLE_OP_FLOW_GET>",
>> + "1" if options.trace_get_op else "0")
>> + source = source.replace("<ENABLE_OP_FLOW_PUT>",
>> + "1" if options.trace_put_op else "0")
>> +
>> b = BPF(text=source, usdt_contexts=[u], debug=options.debug)
>>
>> #
>> # Print header
>> #
>> - print("Display DPIF_OP_EXECUTE operations being queued for transmission
>> "
>> - "onto the netlink socket.")
>> - print("{:<18} {:<4} {:<16} {:<10} {:<10}".format(
>> - "TIME", "CPU", "COMM", "PID", "NL_SIZE"))
>> + print("Display DPIF operations being queued for transmission onto the "
>> + "netlink socket.")
>> + print("{:<18} {:<4} {:<16} {:<10} {:<10} {}".format(
>> + "TIME", "CPU", "COMM", "PID", "NL_SIZE", "DPIF_OPERATION"))
>>
>> #
>> # Dump out all events
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