Robots might generate a long list of singleton element commands such as:
add element t s { 1.0.1.0/24 }
...
add element t s { 1.0.2.0/23 }
collapse them into one single command before the evaluation step, ie.
add element t s { 1.0.1.0/24, ..., 1.0.2.0/23 }
this speeds up overlap detection and set element automerge operations in
this worst case scenario.
Since 3da9643fb9ff9 ("intervals: add support to automerge with kernel
elements"), the new interval tracking relies on mergesort. The pattern
above triggers the set sorting for each element.
This patch adds a list to cmd objects that store collapsed commands.
Moreover, expressions also contain a reference to the original command,
to uncollapse the commands after the evaluation step.
These commands are uncollapsed after the evaluation step to ensure error
reporting works as expected (command and netlink message are mapped
1:1).
For the record:
- nftables versions <= 1.0.2 did not perform any kind of overlap
check for the described scenario above (because set cache only contained
elements in the kernel in this case). This is a problem for kernels < 5.7
which rely on userspace to detect overlaps.
- the overlap detection could be skipped for kernels >= 5.7.
- The extended netlink error reporting available for set elements
since 5.19-rc might allow to remove the uncollapse step, in this case,
error reporting does not rely on the netlink sequence to refer to the
command triggering the problem.
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
@Phil: This is v2, restoring error reporting after the command collapse
operation as you mentioned in your feedback.
Note nftables <= 1.0.2 does not perform any sort of overlap
checking from userspace for the scenario described in this commit,
that's why first nft -f call is "so fast" (set cache was empty in
that case).
include/expression.h | 1 +
include/rule.h | 3 ++
src/libnftables.c | 17 ++++++++--
src/rule.c | 75 ++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 93 insertions(+), 3 deletions(-)
diff --git a/include/expression.h b/include/expression.h
index 2c3818e89b79..53194c9248e4 100644
--- a/include/expression.h
+++ b/include/expression.h
@@ -243,6 +243,7 @@ struct expr {
enum expr_types etype:8;
enum ops op:8;
unsigned int len;
+ struct cmd *cmd;
union {
struct {
diff --git a/include/rule.h b/include/rule.h
index e232b97afed7..908122559cdf 100644
--- a/include/rule.h
+++ b/include/rule.h
@@ -700,6 +700,7 @@ struct cmd {
enum cmd_obj obj;
struct handle handle;
uint32_t seqnum;
+ struct list_head collapse_list;
union {
void *data;
struct expr *expr;
@@ -728,6 +729,8 @@ extern struct cmd *cmd_alloc(enum cmd_ops op, enum cmd_obj obj,
const struct handle *h, const struct location *loc,
void *data);
extern void nft_cmd_expand(struct cmd *cmd);
+extern bool nft_cmd_collapse(struct list_head *cmds);
+extern void nft_cmd_uncollapse(struct list_head *cmds);
extern struct cmd *cmd_alloc_obj_ct(enum cmd_ops op, int type,
const struct handle *h,
const struct location *loc, struct obj *obj);
diff --git a/src/libnftables.c b/src/libnftables.c
index 6a22ea093952..aac682b706ff 100644
--- a/src/libnftables.c
+++ b/src/libnftables.c
@@ -501,7 +501,9 @@ static int nft_evaluate(struct nft_ctx *nft, struct list_head *msgs,
{
struct nft_cache_filter *filter;
struct cmd *cmd, *next;
+ bool collapsed = false;
unsigned int flags;
+ int err = 0;
filter = nft_cache_filter_init();
flags = nft_cache_evaluate(nft, cmds, filter);
@@ -512,17 +514,26 @@ static int nft_evaluate(struct nft_ctx *nft, struct list_head *msgs,
nft_cache_filter_fini(filter);
+ if (nft_cmd_collapse(cmds))
+ collapsed = true;
+
list_for_each_entry_safe(cmd, next, cmds, list) {
struct eval_ctx ectx = {
.nft = nft,
.msgs = msgs,
};
+
if (cmd_evaluate(&ectx, cmd) < 0 &&
- ++nft->state->nerrs == nft->parser_max_errors)
- return -1;
+ ++nft->state->nerrs == nft->parser_max_errors) {
+ err = -1;
+ break;
+ }
}
- if (nft->state->nerrs)
+ if (collapsed)
+ nft_cmd_uncollapse(cmds);
+
+ if (err < 0 || nft->state->nerrs)
return -1;
list_for_each_entry(cmd, cmds, list) {
diff --git a/src/rule.c b/src/rule.c
index 7f61bdc1cec9..0526a1482438 100644
--- a/src/rule.c
+++ b/src/rule.c
@@ -1279,6 +1279,8 @@ struct cmd *cmd_alloc(enum cmd_ops op, enum cmd_obj obj,
cmd->handle = *h;
cmd->location = *loc;
cmd->data = data;
+ init_list_head(&cmd->collapse_list);
+
return cmd;
}
@@ -1379,6 +1381,79 @@ void nft_cmd_expand(struct cmd *cmd)
}
}
+bool nft_cmd_collapse(struct list_head *cmds)
+{
+ struct cmd *cmd, *next, *elems = NULL;
+ struct expr *expr, *enext;
+ bool collapse = false;
+
+ list_for_each_entry_safe(cmd, next, cmds, list) {
+ if (cmd->op != CMD_ADD &&
+ cmd->op != CMD_CREATE) {
+ elems = NULL;
+ continue;
+ }
+
+ if (cmd->obj != CMD_OBJ_ELEMENTS) {
+ elems = NULL;
+ continue;
+ }
+
+ if (!elems) {
+ elems = cmd;
+ continue;
+ }
+
+ if (cmd->op != elems->op) {
+ elems = cmd;
+ continue;
+ }
+
+ if (strcmp(elems->handle.table.name, cmd->handle.table.name) ||
+ strcmp(elems->handle.set.name, cmd->handle.set.name)) {
+ elems = cmd;
+ continue;
+ }
+
+ collapse = true;
+ list_for_each_entry_safe(expr, enext, &cmd->expr->expressions, list) {
+ expr->cmd = cmd;
+ list_move_tail(&expr->list, &elems->expr->expressions);
+ }
+ elems->expr->size += cmd->expr->size;
+ list_move_tail(&cmd->list, &elems->collapse_list);
+ }
+
+ return collapse;
+}
+
+void nft_cmd_uncollapse(struct list_head *cmds)
+{
+ struct cmd *cmd, *cmd_next, *collapse_cmd, *collapse_cmd_next;
+ struct expr *expr, *next;
+
+ list_for_each_entry_safe(cmd, cmd_next, cmds, list) {
+ if (list_empty(&cmd->collapse_list))
+ continue;
+
+ assert(cmd->obj == CMD_OBJ_ELEMENTS);
+
+ list_for_each_entry_safe(expr, next, &cmd->expr->expressions, list) {
+ if (!expr->cmd)
+ continue;
+
+ list_move_tail(&expr->list, &expr->cmd->expr->expressions);
+ cmd->expr->size--;
+ expr->cmd = NULL;
+ }
+
+ list_for_each_entry_safe(collapse_cmd, collapse_cmd_next, &cmd->collapse_list, list) {
+ collapse_cmd->elem.set = set_get(cmd->elem.set);
+ list_add(&collapse_cmd->list, &cmd->list);
+ }
+ }
+}
+
struct markup *markup_alloc(uint32_t format)
{
struct markup *markup;
--
2.30.2
