linux/net/sched/ematch.c

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/*
* net/sched/ematch.c Extended Match API
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Authors: Thomas Graf <tgraf@suug.ch>
*
* ==========================================================================
*
* An extended match (ematch) is a small classification tool not worth
* writing a full classifier for. Ematches can be interconnected to form
* a logic expression and get attached to classifiers to extend their
* functionatlity.
*
* The userspace part transforms the logic expressions into an array
* consisting of multiple sequences of interconnected ematches separated
* by markers. Precedence is implemented by a special ematch kind
* referencing a sequence beyond the marker of the current sequence
* causing the current position in the sequence to be pushed onto a stack
* to allow the current position to be overwritten by the position referenced
* in the special ematch. Matching continues in the new sequence until a
* marker is reached causing the position to be restored from the stack.
*
* Example:
* A AND (B1 OR B2) AND C AND D
*
* ------->-PUSH-------
* -->-- / -->-- \ -->--
* / \ / / \ \ / \
* +-------+-------+-------+-------+-------+--------+
* | A AND | B AND | C AND | D END | B1 OR | B2 END |
* +-------+-------+-------+-------+-------+--------+
* \ /
* --------<-POP---------
*
* where B is a virtual ematch referencing to sequence starting with B1.
*
* ==========================================================================
*
* How to write an ematch in 60 seconds
* ------------------------------------
*
* 1) Provide a matcher function:
* static int my_match(struct sk_buff *skb, struct tcf_ematch *m,
* struct tcf_pkt_info *info)
* {
* struct mydata *d = (struct mydata *) m->data;
*
* if (...matching goes here...)
* return 1;
* else
* return 0;
* }
*
* 2) Fill out a struct tcf_ematch_ops:
* static struct tcf_ematch_ops my_ops = {
* .kind = unique id,
* .datalen = sizeof(struct mydata),
* .match = my_match,
* .owner = THIS_MODULE,
* };
*
* 3) Register/Unregister your ematch:
* static int __init init_my_ematch(void)
* {
* return tcf_em_register(&my_ops);
* }
*
* static void __exit exit_my_ematch(void)
* {
* tcf_em_unregister(&my_ops);
* }
*
* module_init(init_my_ematch);
* module_exit(exit_my_ematch);
*
* 4) By now you should have two more seconds left, barely enough to
* open up a beer to watch the compilation going.
*/
#include <linux/module.h>
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 16:04:11 +08:00
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/rtnetlink.h>
#include <linux/skbuff.h>
#include <net/pkt_cls.h>
static LIST_HEAD(ematch_ops);
static DEFINE_RWLOCK(ematch_mod_lock);
static struct tcf_ematch_ops *tcf_em_lookup(u16 kind)
{
struct tcf_ematch_ops *e = NULL;
read_lock(&ematch_mod_lock);
list_for_each_entry(e, &ematch_ops, link) {
if (kind == e->kind) {
if (!try_module_get(e->owner))
e = NULL;
read_unlock(&ematch_mod_lock);
return e;
}
}
read_unlock(&ematch_mod_lock);
return NULL;
}
/**
* tcf_em_register - register an extended match
*
* @ops: ematch operations lookup table
*
* This function must be called by ematches to announce their presence.
* The given @ops must have kind set to a unique identifier and the
* callback match() must be implemented. All other callbacks are optional
* and a fallback implementation is used instead.
*
* Returns -EEXISTS if an ematch of the same kind has already registered.
*/
int tcf_em_register(struct tcf_ematch_ops *ops)
{
int err = -EEXIST;
struct tcf_ematch_ops *e;
if (ops->match == NULL)
return -EINVAL;
write_lock(&ematch_mod_lock);
list_for_each_entry(e, &ematch_ops, link)
if (ops->kind == e->kind)
goto errout;
list_add_tail(&ops->link, &ematch_ops);
err = 0;
errout:
write_unlock(&ematch_mod_lock);
return err;
}
EXPORT_SYMBOL(tcf_em_register);
/**
* tcf_em_unregister - unregster and extended match
*
* @ops: ematch operations lookup table
*
* This function must be called by ematches to announce their disappearance
* for examples when the module gets unloaded. The @ops parameter must be
* the same as the one used for registration.
*
* Returns -ENOENT if no matching ematch was found.
*/
void tcf_em_unregister(struct tcf_ematch_ops *ops)
{
write_lock(&ematch_mod_lock);
list_del(&ops->link);
write_unlock(&ematch_mod_lock);
}
EXPORT_SYMBOL(tcf_em_unregister);
static inline struct tcf_ematch *tcf_em_get_match(struct tcf_ematch_tree *tree,
int index)
{
return &tree->matches[index];
}
static int tcf_em_validate(struct tcf_proto *tp,
struct tcf_ematch_tree_hdr *tree_hdr,
struct tcf_ematch *em, struct nlattr *nla, int idx)
{
int err = -EINVAL;
struct tcf_ematch_hdr *em_hdr = nla_data(nla);
int data_len = nla_len(nla) - sizeof(*em_hdr);
void *data = (void *) em_hdr + sizeof(*em_hdr);
if (!TCF_EM_REL_VALID(em_hdr->flags))
goto errout;
if (em_hdr->kind == TCF_EM_CONTAINER) {
/* Special ematch called "container", carries an index
* referencing an external ematch sequence.
*/
u32 ref;
if (data_len < sizeof(ref))
goto errout;
ref = *(u32 *) data;
if (ref >= tree_hdr->nmatches)
goto errout;
/* We do not allow backward jumps to avoid loops and jumps
* to our own position are of course illegal.
*/
if (ref <= idx)
goto errout;
em->data = ref;
} else {
/* Note: This lookup will increase the module refcnt
* of the ematch module referenced. In case of a failure,
* a destroy function is called by the underlying layer
* which automatically releases the reference again, therefore
* the module MUST not be given back under any circumstances
* here. Be aware, the destroy function assumes that the
* module is held if the ops field is non zero.
*/
em->ops = tcf_em_lookup(em_hdr->kind);
if (em->ops == NULL) {
err = -ENOENT;
#ifdef CONFIG_MODULES
__rtnl_unlock();
request_module("ematch-kind-%u", em_hdr->kind);
rtnl_lock();
em->ops = tcf_em_lookup(em_hdr->kind);
if (em->ops) {
/* We dropped the RTNL mutex in order to
* perform the module load. Tell the caller
* to replay the request.
*/
module_put(em->ops->owner);
err = -EAGAIN;
}
#endif
goto errout;
}
/* ematch module provides expected length of data, so we
* can do a basic sanity check.
*/
if (em->ops->datalen && data_len < em->ops->datalen)
goto errout;
if (em->ops->change) {
err = em->ops->change(tp, data, data_len, em);
if (err < 0)
goto errout;
} else if (data_len > 0) {
/* ematch module doesn't provide an own change
* procedure and expects us to allocate and copy
* the ematch data.
*
* TCF_EM_SIMPLE may be specified stating that the
* data only consists of a u32 integer and the module
* does not expected a memory reference but rather
* the value carried.
*/
if (em_hdr->flags & TCF_EM_SIMPLE) {
if (data_len < sizeof(u32))
goto errout;
em->data = *(u32 *) data;
} else {
void *v = kmemdup(data, data_len, GFP_KERNEL);
if (v == NULL) {
err = -ENOBUFS;
goto errout;
}
em->data = (unsigned long) v;
}
}
}
em->matchid = em_hdr->matchid;
em->flags = em_hdr->flags;
em->datalen = data_len;
err = 0;
errout:
return err;
}
static const struct nla_policy em_policy[TCA_EMATCH_TREE_MAX + 1] = {
[TCA_EMATCH_TREE_HDR] = { .len = sizeof(struct tcf_ematch_tree_hdr) },
[TCA_EMATCH_TREE_LIST] = { .type = NLA_NESTED },
};
/**
* tcf_em_tree_validate - validate ematch config TLV and build ematch tree
*
* @tp: classifier kind handle
* @nla: ematch tree configuration TLV
* @tree: destination ematch tree variable to store the resulting
* ematch tree.
*
* This function validates the given configuration TLV @nla and builds an
* ematch tree in @tree. The resulting tree must later be copied into
* the private classifier data using tcf_em_tree_change(). You MUST NOT
* provide the ematch tree variable of the private classifier data directly,
* the changes would not be locked properly.
*
* Returns a negative error code if the configuration TLV contains errors.
*/
int tcf_em_tree_validate(struct tcf_proto *tp, struct nlattr *nla,
struct tcf_ematch_tree *tree)
{
int idx, list_len, matches_len, err;
struct nlattr *tb[TCA_EMATCH_TREE_MAX + 1];
struct nlattr *rt_match, *rt_hdr, *rt_list;
struct tcf_ematch_tree_hdr *tree_hdr;
struct tcf_ematch *em;
[PKT_SCHED] ematch: oops from uninitialized variable (resend) Setting up a meta match causes a kernel OOPS because of uninitialized elements in tree. [ 37.322381] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 [ 37.322381] IP: [<ffffffff883fc717>] :em_meta:em_meta_destroy+0x17/0x80 [ 37.322381] Call Trace: [ 37.322381] [<ffffffff803ec83d>] tcf_em_tree_destroy+0x2d/0xa0 [ 37.322381] [<ffffffff803ecc8c>] tcf_em_tree_validate+0x2dc/0x4a0 [ 37.322381] [<ffffffff803f06d2>] nla_parse+0x92/0xe0 [ 37.322381] [<ffffffff883f9672>] :cls_basic:basic_change+0x202/0x3c0 [ 37.322381] [<ffffffff802a3917>] kmem_cache_alloc+0x67/0xa0 [ 37.322381] [<ffffffff803ea221>] tc_ctl_tfilter+0x3b1/0x580 [ 37.322381] [<ffffffff803dffd0>] rtnetlink_rcv_msg+0x0/0x260 [ 37.322381] [<ffffffff803ee944>] netlink_rcv_skb+0x74/0xa0 [ 37.322381] [<ffffffff803dffc8>] rtnetlink_rcv+0x18/0x20 [ 37.322381] [<ffffffff803ee6c3>] netlink_unicast+0x263/0x290 [ 37.322381] [<ffffffff803cf276>] __alloc_skb+0x96/0x160 [ 37.322381] [<ffffffff803ef014>] netlink_sendmsg+0x274/0x340 [ 37.322381] [<ffffffff803c7c3b>] sock_sendmsg+0x12b/0x140 [ 37.322381] [<ffffffff8024de90>] autoremove_wake_function+0x0/0x30 [ 37.322381] [<ffffffff8024de90>] autoremove_wake_function+0x0/0x30 [ 37.322381] [<ffffffff803c7c3b>] sock_sendmsg+0x12b/0x140 [ 37.322381] [<ffffffff80288611>] zone_statistics+0xb1/0xc0 [ 37.322381] [<ffffffff803c7e5e>] sys_sendmsg+0x20e/0x360 [ 37.322381] [<ffffffff803c7411>] sockfd_lookup_light+0x41/0x80 [ 37.322381] [<ffffffff8028d04b>] handle_mm_fault+0x3eb/0x7f0 [ 37.322381] [<ffffffff8020c2fb>] system_call_after_swapgs+0x7b/0x80 Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-02-09 19:47:19 +08:00
memset(tree, 0, sizeof(*tree));
if (!nla)
return 0;
err = nla_parse_nested(tb, TCA_EMATCH_TREE_MAX, nla, em_policy);
if (err < 0)
goto errout;
err = -EINVAL;
rt_hdr = tb[TCA_EMATCH_TREE_HDR];
rt_list = tb[TCA_EMATCH_TREE_LIST];
if (rt_hdr == NULL || rt_list == NULL)
goto errout;
tree_hdr = nla_data(rt_hdr);
memcpy(&tree->hdr, tree_hdr, sizeof(*tree_hdr));
rt_match = nla_data(rt_list);
list_len = nla_len(rt_list);
matches_len = tree_hdr->nmatches * sizeof(*em);
tree->matches = kzalloc(matches_len, GFP_KERNEL);
if (tree->matches == NULL)
goto errout;
/* We do not use nla_parse_nested here because the maximum
* number of attributes is unknown. This saves us the allocation
* for a tb buffer which would serve no purpose at all.
*
* The array of rt attributes is parsed in the order as they are
* provided, their type must be incremental from 1 to n. Even
* if it does not serve any real purpose, a failure of sticking
* to this policy will result in parsing failure.
*/
for (idx = 0; nla_ok(rt_match, list_len); idx++) {
err = -EINVAL;
if (rt_match->nla_type != (idx + 1))
goto errout_abort;
if (idx >= tree_hdr->nmatches)
goto errout_abort;
if (nla_len(rt_match) < sizeof(struct tcf_ematch_hdr))
goto errout_abort;
em = tcf_em_get_match(tree, idx);
err = tcf_em_validate(tp, tree_hdr, em, rt_match, idx);
if (err < 0)
goto errout_abort;
rt_match = nla_next(rt_match, &list_len);
}
/* Check if the number of matches provided by userspace actually
* complies with the array of matches. The number was used for
* the validation of references and a mismatch could lead to
* undefined references during the matching process.
*/
if (idx != tree_hdr->nmatches) {
err = -EINVAL;
goto errout_abort;
}
err = 0;
errout:
return err;
errout_abort:
tcf_em_tree_destroy(tp, tree);
return err;
}
EXPORT_SYMBOL(tcf_em_tree_validate);
/**
* tcf_em_tree_destroy - destroy an ematch tree
*
* @tp: classifier kind handle
* @tree: ematch tree to be deleted
*
* This functions destroys an ematch tree previously created by
* tcf_em_tree_validate()/tcf_em_tree_change(). You must ensure that
* the ematch tree is not in use before calling this function.
*/
void tcf_em_tree_destroy(struct tcf_proto *tp, struct tcf_ematch_tree *tree)
{
int i;
if (tree->matches == NULL)
return;
for (i = 0; i < tree->hdr.nmatches; i++) {
struct tcf_ematch *em = tcf_em_get_match(tree, i);
if (em->ops) {
if (em->ops->destroy)
em->ops->destroy(tp, em);
else if (!tcf_em_is_simple(em))
kfree((void *) em->data);
module_put(em->ops->owner);
}
}
tree->hdr.nmatches = 0;
kfree(tree->matches);
tree->matches = NULL;
}
EXPORT_SYMBOL(tcf_em_tree_destroy);
/**
* tcf_em_tree_dump - dump ematch tree into a rtnl message
*
* @skb: skb holding the rtnl message
* @t: ematch tree to be dumped
* @tlv: TLV type to be used to encapsulate the tree
*
* This function dumps a ematch tree into a rtnl message. It is valid to
* call this function while the ematch tree is in use.
*
* Returns -1 if the skb tailroom is insufficient.
*/
int tcf_em_tree_dump(struct sk_buff *skb, struct tcf_ematch_tree *tree, int tlv)
{
int i;
u8 *tail;
struct nlattr *top_start;
struct nlattr *list_start;
top_start = nla_nest_start(skb, tlv);
if (top_start == NULL)
goto nla_put_failure;
NLA_PUT(skb, TCA_EMATCH_TREE_HDR, sizeof(tree->hdr), &tree->hdr);
list_start = nla_nest_start(skb, TCA_EMATCH_TREE_LIST);
if (list_start == NULL)
goto nla_put_failure;
tail = skb_tail_pointer(skb);
for (i = 0; i < tree->hdr.nmatches; i++) {
struct nlattr *match_start = (struct nlattr *)tail;
struct tcf_ematch *em = tcf_em_get_match(tree, i);
struct tcf_ematch_hdr em_hdr = {
.kind = em->ops ? em->ops->kind : TCF_EM_CONTAINER,
.matchid = em->matchid,
.flags = em->flags
};
NLA_PUT(skb, i + 1, sizeof(em_hdr), &em_hdr);
if (em->ops && em->ops->dump) {
if (em->ops->dump(skb, em) < 0)
goto nla_put_failure;
} else if (tcf_em_is_container(em) || tcf_em_is_simple(em)) {
u32 u = em->data;
nla_put_nohdr(skb, sizeof(u), &u);
} else if (em->datalen > 0)
nla_put_nohdr(skb, em->datalen, (void *) em->data);
tail = skb_tail_pointer(skb);
match_start->nla_len = tail - (u8 *)match_start;
}
nla_nest_end(skb, list_start);
nla_nest_end(skb, top_start);
return 0;
nla_put_failure:
return -1;
}
EXPORT_SYMBOL(tcf_em_tree_dump);
static inline int tcf_em_match(struct sk_buff *skb, struct tcf_ematch *em,
struct tcf_pkt_info *info)
{
int r = em->ops->match(skb, em, info);
return tcf_em_is_inverted(em) ? !r : r;
}
/* Do not use this function directly, use tcf_em_tree_match instead */
int __tcf_em_tree_match(struct sk_buff *skb, struct tcf_ematch_tree *tree,
struct tcf_pkt_info *info)
{
int stackp = 0, match_idx = 0, res = 0;
struct tcf_ematch *cur_match;
int stack[CONFIG_NET_EMATCH_STACK];
proceed:
while (match_idx < tree->hdr.nmatches) {
cur_match = tcf_em_get_match(tree, match_idx);
if (tcf_em_is_container(cur_match)) {
if (unlikely(stackp >= CONFIG_NET_EMATCH_STACK))
goto stack_overflow;
stack[stackp++] = match_idx;
match_idx = cur_match->data;
goto proceed;
}
res = tcf_em_match(skb, cur_match, info);
if (tcf_em_early_end(cur_match, res))
break;
match_idx++;
}
pop_stack:
if (stackp > 0) {
match_idx = stack[--stackp];
cur_match = tcf_em_get_match(tree, match_idx);
if (tcf_em_early_end(cur_match, res))
goto pop_stack;
else {
match_idx++;
goto proceed;
}
}
return res;
stack_overflow:
if (net_ratelimit())
pr_warning("tc ematch: local stack overflow,"
" increase NET_EMATCH_STACK\n");
return -1;
}
EXPORT_SYMBOL(__tcf_em_tree_match);