[RFC v3 14/22] bpf/cgroup: Make cgroup_bpf_update() return an error code

[Mickaël Salaün]

This will be useful to support Landlock for the next commits.

Signed-off-by: Mickaël Salaün <m...@digikod.net>
Cc: Alexei Starovoitov <a...@kernel.org>
Cc: Daniel Borkmann <dan...@iogearbox.net>
Cc: Daniel Mack <dan...@zonque.org>
Cc: David S. Miller <da...@davemloft.net>
Cc: Tejun Heo <t...@kernel.org>
---
 include/linux/bpf-cgroup.h |  4 ++--
 kernel/bpf/cgroup.c        |  3 ++-
 kernel/bpf/syscall.c       | 10 ++++++----
 kernel/cgroup.c            |  6 ++++--
 4 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index 2234042d7f61..6cca7924ee17 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -31,13 +31,13 @@ struct cgroup_bpf {
 void cgroup_bpf_put(struct cgroup *cgrp);
 void cgroup_bpf_inherit(struct cgroup *cgrp, struct cgroup *parent);
 
-void __cgroup_bpf_update(struct cgroup *cgrp,
+int __cgroup_bpf_update(struct cgroup *cgrp,
                         struct cgroup *parent,
                         struct bpf_prog *prog,
                         enum bpf_attach_type type);
 
 /* Wrapper for __cgroup_bpf_update() protected by cgroup_mutex */
-void cgroup_bpf_update(struct cgroup *cgrp,
+int cgroup_bpf_update(struct cgroup *cgrp,
                       struct bpf_prog *prog,
                       enum bpf_attach_type type);
 
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 782878ec4f2d..7b75fa692617 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -83,7 +83,7 @@ void cgroup_bpf_inherit(struct cgroup *cgrp, struct cgroup 
*parent)
  *
  * Must be called with cgroup_mutex held.
  */
-void __cgroup_bpf_update(struct cgroup *cgrp,
+int __cgroup_bpf_update(struct cgroup *cgrp,
                         struct cgroup *parent,
                         struct bpf_prog *prog,
                         enum bpf_attach_type type)
@@ -117,6 +117,7 @@ void __cgroup_bpf_update(struct cgroup *cgrp,
                bpf_prog_put(old_pinned.prog);
                static_branch_dec(&cgroup_bpf_enabled_key);
        }
+       return 0;
 }
 
 /**
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 45a91d511119..c978f2d9a1b3 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -831,6 +831,7 @@ static int bpf_prog_attach(const union bpf_attr *attr)
 {
        struct bpf_prog *prog;
        struct cgroup *cgrp;
+       int result;
 
        if (!capable(CAP_NET_ADMIN))
                return -EPERM;
@@ -858,10 +859,10 @@ static int bpf_prog_attach(const union bpf_attr *attr)
                return PTR_ERR(cgrp);
        }
 
-       cgroup_bpf_update(cgrp, prog, attr->attach_type);
+       result = cgroup_bpf_update(cgrp, prog, attr->attach_type);
        cgroup_put(cgrp);
 
-       return 0;
+       return result;
 }
 
 #define BPF_PROG_DETACH_LAST_FIELD attach_type
@@ -869,6 +870,7 @@ static int bpf_prog_attach(const union bpf_attr *attr)
 static int bpf_prog_detach(const union bpf_attr *attr)
 {
        struct cgroup *cgrp;
+       int result = 0;
 
        if (!capable(CAP_NET_ADMIN))
                return -EPERM;
@@ -883,7 +885,7 @@ static int bpf_prog_detach(const union bpf_attr *attr)
                if (IS_ERR(cgrp))
                        return PTR_ERR(cgrp);
 
-               cgroup_bpf_update(cgrp, NULL, attr->attach_type);
+               result = cgroup_bpf_update(cgrp, NULL, attr->attach_type);
                cgroup_put(cgrp);
                break;
 
@@ -891,7 +893,7 @@ static int bpf_prog_detach(const union bpf_attr *attr)
                return -EINVAL;
        }
 
-       return 0;
+       return result;
 }
 #endif /* CONFIG_CGROUP_BPF */
 
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 87324ce481b1..48b650a640a9 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -6450,15 +6450,17 @@ static __init int cgroup_namespaces_init(void)
 subsys_initcall(cgroup_namespaces_init);
 
 #ifdef CONFIG_CGROUP_BPF
-void cgroup_bpf_update(struct cgroup *cgrp,
+int cgroup_bpf_update(struct cgroup *cgrp,
                       struct bpf_prog *prog,
                       enum bpf_attach_type type)
 {
        struct cgroup *parent = cgroup_parent(cgrp);
+       int result;
 
        mutex_lock(&cgroup_mutex);
-       __cgroup_bpf_update(cgrp, parent, prog, type);
+       result = __cgroup_bpf_update(cgrp, parent, prog, type);
        mutex_unlock(&cgroup_mutex);
+       return result;
 }
 #endif /* CONFIG_CGROUP_BPF */
 
-- 
2.9.3