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    Subject[RFC v3 14/22] bpf/cgroup: Make cgroup_bpf_update() return an error code
    Date
    This will be useful to support Landlock for the next commits.

    Signed-off-by: Mickaël Salaün <mic@digikod.net>
    Cc: Alexei Starovoitov <ast@kernel.org>
    Cc: Daniel Borkmann <daniel@iogearbox.net>
    Cc: Daniel Mack <daniel@zonque.org>
    Cc: David S. Miller <davem@davemloft.net>
    Cc: Tejun Heo <tj@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
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