linux.git/net/ipv6/netfilter, branch v2.6.23

[NETFILTER]: Fix/improve deadlock condition on module removal netfilter

2007-09-11T09:28:26+00:00

So I've had a deadlock reported to me.  I've found that the sequence of
events goes like this:

1) process A (modprobe) runs to remove ip_tables.ko

2) process B (iptables-restore) runs and calls setsockopt on a netfilter socket,
increasing the ip_tables socket_ops use count

3) process A acquires a file lock on the file ip_tables.ko, calls remove_module
in the kernel, which in turn executes the ip_tables module cleanup routine,
which calls nf_unregister_sockopt

4) nf_unregister_sockopt, seeing that the use count is non-zero, puts the
calling process into uninterruptible sleep, expecting the process using the
socket option code to wake it up when it exits the kernel

4) the user of the socket option code (process B) in do_ipt_get_ctl, calls
ipt_find_table_lock, which in this case calls request_module to load
ip_tables_nat.ko

5) request_module forks a copy of modprobe (process C) to load the module and
blocks until modprobe exits.

6) Process C. forked by request_module process the dependencies of
ip_tables_nat.ko, of which ip_tables.ko is one.

7) Process C attempts to lock the request module and all its dependencies, it
blocks when it attempts to lock ip_tables.ko (which was previously locked in
step 3)

Theres not really any great permanent solution to this that I can see, but I've
developed a two part solution that corrects the problem

Part 1) Modifies the nf_sockopt registration code so that, instead of using a
use counter internal to the nf_sockopt_ops structure, we instead use a pointer
to the registering modules owner to do module reference counting when nf_sockopt
calls a modules set/get routine.  This prevents the deadlock by preventing set 4
from happening.

Part 2) Enhances the modprobe utilty so that by default it preforms non-blocking
remove operations (the same way rmmod does), and add an option to explicity
request blocking operation.  So if you select blocking operation in modprobe you
can still cause the above deadlock, but only if you explicity try (and since
root can do any old stupid thing it would like....  :)  ).

Signed-off-by: Neil Horman 
Signed-off-by: Patrick McHardy 
Signed-off-by: David S. Miller

[NETFILTER]: Make nf_ct_ipv6_skip_exthdr() static.

2007-07-31T09:28:26+00:00

nf_ct_ipv6_skip_exthdr() can now become static.

Signed-off-by: Adrian Bunk 
Signed-off-by: David S. Miller

[NETFILTER]: Fix logging regression

2007-07-24T22:29:55+00:00

Loading one of the LOG target fails if a different target has already
registered itself as backend for the same family. This can affect the
ipt_LOG and ipt_ULOG modules when both are loaded.

Reported and tested by: 

Signed-off-by: Patrick McHardy 
Signed-off-by: David S. Miller

[NETFILTER]: nf_conntrack: mark protocols __read_mostly

2007-07-15T03:48:19+00:00

Also remove two unnecessary EXPORT_SYMBOLs and move the
nf_conntrack_l3proto_ipv4 declaration to the correct file.

Signed-off-by: Patrick McHardy 
Signed-off-by: David S. Miller

[NETFILTER]: Lower *tables printk severity

2007-07-15T03:46:15+00:00

Lower ip6tables, arptables and ebtables printk severity similar to
Dan Aloni's patch for iptables.

Signed-off-by: Patrick McHardy 
Signed-off-by: David S. Miller

[NETFILTER]: nf_conntrack: Introduces nf_ct_get_tuplepr and uses it

2007-07-15T03:45:14+00:00

nf_ct_get_tuple() requires the offset to transport header and that bothers
callers such as icmp[v6] l4proto modules. This introduces new function
to simplify them.

Signed-off-by: Yasuyuki Kozakai 
Signed-off-by: Patrick McHardy 
Signed-off-by: David S. Miller

[NETFILTER]: nf_conntrack: make l3proto->prepare() generic and renames it

2007-07-15T03:44:50+00:00

The icmp[v6] l4proto modules parse headers in ICMP[v6] error to get tuple.
But they have to find the offset to transport protocol header before that.
Their processings are almost same as prepare() of l3proto modules.
This makes prepare() more generic to simplify icmp[v6] l4proto module
later.

Signed-off-by: Yasuyuki Kozakai 
Signed-off-by: Patrick McHardy 
Signed-off-by: David S. Miller

[NETFILTER]: nf_conntrack: Increment error count on parsing IPv4 header

2007-07-15T03:44:23+00:00

Signed-off-by: Yasuyuki Kozakai 
Signed-off-by: Patrick McHardy 
Signed-off-by: David S. Miller

[NETFILTER]: Convert DEBUGP to pr_debug

2007-07-11T05:18:20+00:00

Convert DEBUGP to pr_debug and fix lots of non-compiling debug statements.

Signed-off-by: Patrick McHardy 
Signed-off-by: David S. Miller

[NETFILTER]: nf_conntrack: remove 'ignore_conntrack' argument from nf_conntrack_find_get

2007-07-11T05:17:41+00:00

All callers pass NULL, this also doesn't seem very useful for modules.

Signed-off-by: Patrick McHardy 
Signed-off-by: David S. Miller