2024-02-01 13:10:16

by Michal Koutný

[permalink] [raw]
Subject: [PATCH v5 3/4] net/sched: Load modules via their alias

The cls_,sch_,act_ modules may be loaded lazily during network
configuration but without user's awareness and control.

Switch the lazy loading from canonical module names to a module alias.
This allows finer control over lazy loading, the precedent from
commit 7f78e0351394 ("fs: Limit sys_mount to only request filesystem
modules.") explains it already:

Using aliases means user space can control the policy of which
filesystem^W net/sched modules are auto-loaded by editing
/etc/modprobe.d/*.conf with blacklist and alias directives.
Allowing simple, safe, well understood work-arounds to known
problematic software.

By default, nothing changes. However, if a specific module is
blacklisted (its canonical name), it won't be modprobe'd when requested
under its alias (i.e. kernel auto-loading). It would appear as if the
given module was unknown.

The module can still be loaded under its canonical name, which is an
explicit (privileged) user action.

Signed-off-by: Michal Koutný <[email protected]>
---
net/sched/act_api.c | 2 +-
net/sched/cls_api.c | 2 +-
net/sched/sch_api.c | 4 ++--
3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 3e30d7260493..9ee622fb1160 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -1363,7 +1363,7 @@ struct tc_action_ops *tc_action_load_ops(struct nlattr *nla, u32 flags,

if (rtnl_held)
rtnl_unlock();
- request_module("act_%s", act_name);
+ request_module(NET_ACT_ALIAS_PREFIX "%s", act_name);
if (rtnl_held)
rtnl_lock();

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index ff3d396a65aa..ca5676b2668e 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -257,7 +257,7 @@ tcf_proto_lookup_ops(const char *kind, bool rtnl_held,
#ifdef CONFIG_MODULES
if (rtnl_held)
rtnl_unlock();
- request_module("cls_%s", kind);
+ request_module(NET_CLS_ALIAS_PREFIX "%s", kind);
if (rtnl_held)
rtnl_lock();
ops = __tcf_proto_lookup_ops(kind);
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 36b025cc4fd2..9d928f6a473a 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -228,7 +228,7 @@ int qdisc_set_default(const char *name)
if (!ops) {
/* Not found, drop lock and try to load module */
write_unlock(&qdisc_mod_lock);
- request_module("sch_%s", name);
+ request_module(NET_SCH_ALIAS_PREFIX "%s", name);
write_lock(&qdisc_mod_lock);

ops = qdisc_lookup_default(name);
@@ -1275,7 +1275,7 @@ static struct Qdisc *qdisc_create(struct net_device *dev,
* go away in the mean time.
*/
rtnl_unlock();
- request_module("sch_%s", name);
+ request_module(NET_SCH_ALIAS_PREFIX "%s", name);
rtnl_lock();
ops = qdisc_lookup_ops(kind);
if (ops != NULL) {
--
2.43.0