Make bpf_link update support more generic by making it into another
bpf_link_ops methods. This allows generic syscall handling code to be agnostic
to various conditionally compiled features (e.g., the case of
CONFIG_CGROUP_BPF). This also allows to keep link type-specific code to remain
static within respective code base. Refactor existing bpf_cgroup_link code and
take advantage of this.
Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
---
include/linux/bpf-cgroup.h | 12 ------------
include/linux/bpf.h | 3 ++-
kernel/bpf/cgroup.c | 30 ++++++++++++++++++++++++++++--
kernel/bpf/syscall.c | 11 ++++-------
kernel/cgroup/cgroup.c | 27 ---------------------------
5 files changed, 34 insertions(+), 49 deletions(-)
diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index c11b413d5b1a..d2d969669564 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -100,8 +100,6 @@ int __cgroup_bpf_attach(struct cgroup *cgrp,
int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
struct bpf_cgroup_link *link,
enum bpf_attach_type type);
-int __cgroup_bpf_replace(struct cgroup *cgrp, struct bpf_cgroup_link *link,
- struct bpf_prog *new_prog);
int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
union bpf_attr __user *uattr);
@@ -112,8 +110,6 @@ int cgroup_bpf_attach(struct cgroup *cgrp,
u32 flags);
int cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
enum bpf_attach_type type);
-int cgroup_bpf_replace(struct bpf_link *link, struct bpf_prog *old_prog,
- struct bpf_prog *new_prog);
int cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
union bpf_attr __user *uattr);
@@ -354,7 +350,6 @@ int cgroup_bpf_prog_query(const union bpf_attr *attr,
#else
struct bpf_prog;
-struct bpf_link;
struct cgroup_bpf {};
static inline int cgroup_bpf_inherit(struct cgroup *cgrp) { return 0; }
static inline void cgroup_bpf_offline(struct cgroup *cgrp) {}
@@ -378,13 +373,6 @@ static inline int cgroup_bpf_link_attach(const union bpf_attr *attr,
return -EINVAL;
}
-static inline int cgroup_bpf_replace(struct bpf_link *link,
- struct bpf_prog *old_prog,
- struct bpf_prog *new_prog)
-{
- return -EINVAL;
-}
-
static inline int cgroup_bpf_prog_query(const union bpf_attr *attr,
union bpf_attr __user *uattr)
{
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 25da6ff2a880..20bcac258d1f 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1093,7 +1093,8 @@ struct bpf_link {
struct bpf_link_ops {
void (*release)(struct bpf_link *link);
void (*dealloc)(struct bpf_link *link);
-
+ int (*update_prog)(struct bpf_link *link, struct bpf_prog *new_prog,
+ struct bpf_prog *old_prog);
};
void bpf_link_init(struct bpf_link *link, const struct bpf_link_ops *ops,
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 4d748c5785bc..27a223bcc44c 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -557,8 +557,9 @@ static void replace_effective_prog(struct cgroup *cgrp,
*
* Must be called with cgroup_mutex held.
*/
-int __cgroup_bpf_replace(struct cgroup *cgrp, struct bpf_cgroup_link *link,
- struct bpf_prog *new_prog)
+static int __cgroup_bpf_replace(struct cgroup *cgrp,
+ struct bpf_cgroup_link *link,
+ struct bpf_prog *new_prog)
{
struct list_head *progs = &cgrp->bpf.progs[link->type];
struct bpf_prog *old_prog;
@@ -583,6 +584,30 @@ int __cgroup_bpf_replace(struct cgroup *cgrp, struct bpf_cgroup_link *link,
return 0;
}
+static int cgroup_bpf_replace(struct bpf_link *link, struct bpf_prog *new_prog,
+ struct bpf_prog *old_prog)
+{
+ struct bpf_cgroup_link *cg_link;
+ int ret;
+
+ cg_link = container_of(link, struct bpf_cgroup_link, link);
+
+ mutex_lock(&cgroup_mutex);
+ /* link might have been auto-released by dying cgroup, so fail */
+ if (!cg_link->cgroup) {
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+ if (old_prog && link->prog != old_prog) {
+ ret = -EPERM;
+ goto out_unlock;
+ }
+ ret = __cgroup_bpf_replace(cg_link->cgroup, cg_link, new_prog);
+out_unlock:
+ mutex_unlock(&cgroup_mutex);
+ return ret;
+}
+
static struct bpf_prog_list *find_detach_entry(struct list_head *progs,
struct bpf_prog *prog,
struct bpf_cgroup_link *link,
@@ -811,6 +836,7 @@ static void bpf_cgroup_link_dealloc(struct bpf_link *link)
const struct bpf_link_ops bpf_cgroup_link_lops = {
.release = bpf_cgroup_link_release,
.dealloc = bpf_cgroup_link_dealloc,
+ .update_prog = cgroup_bpf_replace,
};
int cgroup_bpf_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index d85f37239540..84518853648a 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3640,13 +3640,10 @@ static int link_update(union bpf_attr *attr)
}
}
-#ifdef CONFIG_CGROUP_BPF
- if (link->ops == &bpf_cgroup_link_lops) {
- ret = cgroup_bpf_replace(link, old_prog, new_prog);
- goto out_put_progs;
- }
-#endif
- ret = -EINVAL;
+ if (link->ops->update_prog)
+ ret = link->ops->update_prog(link, new_prog, old_prog);
+ else
+ ret = EINVAL;
out_put_progs:
if (old_prog)
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 06b5ea9d899d..557a9b9d2244 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -6508,33 +6508,6 @@ int cgroup_bpf_attach(struct cgroup *cgrp,
return ret;
}
-int cgroup_bpf_replace(struct bpf_link *link, struct bpf_prog *old_prog,
- struct bpf_prog *new_prog)
-{
- struct bpf_cgroup_link *cg_link;
- int ret;
-
- if (link->ops != &bpf_cgroup_link_lops)
- return -EINVAL;
-
- cg_link = container_of(link, struct bpf_cgroup_link, link);
-
- mutex_lock(&cgroup_mutex);
- /* link might have been auto-released by dying cgroup, so fail */
- if (!cg_link->cgroup) {
- ret = -EINVAL;
- goto out_unlock;
- }
- if (old_prog && link->prog != old_prog) {
- ret = -EPERM;
- goto out_unlock;
- }
- ret = __cgroup_bpf_replace(cg_link->cgroup, cg_link, new_prog);
-out_unlock:
- mutex_unlock(&cgroup_mutex);
- return ret;
-}
-
int cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
enum bpf_attach_type type)
{
--
2.24.1
