and remove all O(N) sequences from kernel critical sections in ipfw.
In detail:
1. introduce a IPFW_UH_LOCK to arbitrate requests from
the upper half of the kernel. Some things, such as 'ipfw show',
can be done holding this lock in read mode, whereas insert and
delete require IPFW_UH_WLOCK.
2. introduce a mapping structure to keep rules together. This replaces
the 'next' chain currently used in ipfw rules. At the moment
the map is a simple array (sorted by rule number and then rule_id),
so we can find a rule quickly instead of having to scan the list.
This reduces many expensive lookups from O(N) to O(log N).
3. when an expensive operation (such as insert or delete) is done
by userland, we grab IPFW_UH_WLOCK, create a new copy of the map
without blocking the bottom half of the kernel, then acquire
IPFW_WLOCK and quickly update pointers to the map and related info.
After dropping IPFW_LOCK we can then continue the cleanup protected
by IPFW_UH_LOCK. So userland still costs O(N) but the kernel side
is only blocked for O(1).
4. do not pass pointers to rules through dummynet, netgraph, divert etc,
but rather pass a <slot, chain_id, rulenum, rule_id> tuple.
We validate the slot index (in the array of #2) with chain_id,
and if successful do a O(1) dereference; otherwise, we can find
the rule in O(log N) through <rulenum, rule_id>
All the above does not change the userland/kernel ABI, though there
are some disgusting casts between pointers and uint32_t
Operation costs now are as follows:
Function Old Now Planned
-------------------------------------------------------------------
+ skipto X, non cached O(N) O(log N)
+ skipto X, cached O(1) O(1)
XXX dynamic rule lookup O(1) O(log N) O(1)
+ skipto tablearg O(N) O(1)
+ reinject, non cached O(N) O(log N)
+ reinject, cached O(1) O(1)
+ kernel blocked during setsockopt() O(N) O(1)
-------------------------------------------------------------------
The only (very small) regression is on dynamic rule lookup and this will
be fixed in a day or two, without changing the userland/kernel ABI
Supported by: Valeria Paoli
MFC after: 1 month
+ in many places, replace &V_layer3_chain with a local
variable chain;
+ bring the counter of rules and static_len within ip_fw_chain
replacing static variables;
+ remove some spurious comments and extern declaration;
+ document which lock protects certain data structures
similar to pflog(4).
To use the feature, just put the 'log' options on rules
you are interested in, e.g.
ipfw add 5000 count log ....
and run
tcpdump -ni ipfw0 ...
net.inet.ip.fw.verbose=0 enables logging to ipfw0,
net.inet.ip.fw.verbose=1 sends logging to syslog as before.
More features can be added, similar to pflog(), to store in
the MAC header metadata such as rule numbers and actions.
Manpage to come once features are settled.
- move global variables around to reduce the scope and make them
static if possible;
- add an ipfw_ prefix to all public functions to prevent conflicts
(the same should be done for variables);
- try to pack variable declaration in an uniform way across files;
- clarify some comments;
- remove some misspelling of names (#define V_foo VNET(bar)) that
slipped in due to cut&paste
- remove duplicate static variables in different files;
MFC after: 1 month
and the sockopt routines (the upper half of the kernel).
Whoever is the author of the 'table' code (Ruslan/glebius/oleg ?)
please change the attribution in ip_fw_table.c. I have copied
the copyright line from ip_fw2.c but it carries my name and I have
neither written nor designed the feature so I don't deserve
the credit.
MFC after: 1 month
At this time we pull out from ip_fw2.c the logging functions, and
support for dynamic rules, and move kernel-only stuff into
netinet/ipfw/ip_fw_private.h
No ABI change involved in this commit, unless I made some mistake.
ip_fw.h has changed, though not in the userland-visible part.
Files touched by this commit:
conf/files
now references the two new source files
netinet/ip_fw.h
remove kernel-only definitions gone into netinet/ipfw/ip_fw_private.h.
netinet/ipfw/ip_fw_private.h
new file with kernel-specific ipfw definitions
netinet/ipfw/ip_fw_log.c
ipfw_log and related functions
netinet/ipfw/ip_fw_dynamic.c
code related to dynamic rules
netinet/ipfw/ip_fw2.c
removed the pieces that goes in the new files
netinet/ipfw/ip_fw_nat.c
minor rearrangement to remove LOOKUP_NAT from the
main headers. This require a new function pointer.
A bunch of other kernel files that included netinet/ip_fw.h now
require netinet/ipfw/ip_fw_private.h as well.
Not 100% sure i caught all of them.
MFC after: 1 month
