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| author |   Alexei Starovoitov <ast@kernel.org> | 2020-08-18 21:27:56 -0700 |
|---|---|---|
| committer |   Daniel Borkmann <daniel@iogearbox.net> | 2020-08-20 16:02:36 +0200 |
| commit | 005142b8a1f0f32d33fbe04b728464c1b7acfa0e (patch) | |
| tree | bf08f0b09cdf8308afb0e66cc9132f2be866d9a9 | |
| parent | libbpf: Simplify the return expression of build_map_pin_path() (diff) | |
| download | wireguard-linux-005142b8a1f0f32d33fbe04b728464c1b7acfa0e.tar.xz wireguard-linux-005142b8a1f0f32d33fbe04b728464c1b7acfa0e.zip | |
bpf: Factor out bpf_link_by_id() helper.
Refactor the code a bit to extract bpf_link_by_id() helper.
It's similar to existing bpf_prog_by_id().
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200819042759.51280-2-alexei.starovoitov@gmail.com
| -rw-r--r-- | include/linux/bpf.h | 1 | ||||
| -rw-r--r-- | kernel/bpf/syscall.c | 46 |
2 files changed, 29 insertions, 18 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 55f694b63164..a9b7185a6b37 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1358,6 +1358,7 @@ int btf_check_type_match(struct bpf_verifier_env *env, struct bpf_prog *prog, struct btf *btf, const struct btf_type *t); struct bpf_prog *bpf_prog_by_id(u32 id); +struct bpf_link *bpf_link_by_id(u32 id); const struct bpf_func_proto *bpf_base_func_proto(enum bpf_func_id func_id); #else /* !CONFIG_BPF_SYSCALL */ diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 86299a292214..689d736b6904 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -4014,40 +4014,50 @@ static int link_detach(union bpf_attr *attr) return ret; } -static int bpf_link_inc_not_zero(struct bpf_link *link) +static struct bpf_link *bpf_link_inc_not_zero(struct bpf_link *link) { - return atomic64_fetch_add_unless(&link->refcnt, 1, 0) ? 0 : -ENOENT; + return atomic64_fetch_add_unless(&link->refcnt, 1, 0) ? link : ERR_PTR(-ENOENT); } -#define BPF_LINK_GET_FD_BY_ID_LAST_FIELD link_id - -static int bpf_link_get_fd_by_id(const union bpf_attr *attr) +struct bpf_link *bpf_link_by_id(u32 id) { struct bpf_link *link; - u32 id = attr->link_id; - int fd, err; - if (CHECK_ATTR(BPF_LINK_GET_FD_BY_ID)) - return -EINVAL; - - if (!capable(CAP_SYS_ADMIN)) - return -EPERM; + if (!id) + return ERR_PTR(-ENOENT); spin_lock_bh(&link_idr_lock); - link = idr_find(&link_idr, id); /* before link is "settled", ID is 0, pretend it doesn't exist yet */ + link = idr_find(&link_idr, id); if (link) { if (link->id) - err = bpf_link_inc_not_zero(link); + link = bpf_link_inc_not_zero(link); else - err = -EAGAIN; + link = ERR_PTR(-EAGAIN); } else { - err = -ENOENT; + link = ERR_PTR(-ENOENT); } spin_unlock_bh(&link_idr_lock); + return link; +} - if (err) - return err; +#define BPF_LINK_GET_FD_BY_ID_LAST_FIELD link_id + +static int bpf_link_get_fd_by_id(const union bpf_attr *attr) +{ + struct bpf_link *link; + u32 id = attr->link_id; + int fd; + + if (CHECK_ATTR(BPF_LINK_GET_FD_BY_ID)) + return -EINVAL; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + link = bpf_link_by_id(id); + if (IS_ERR(link)) + return PTR_ERR(link); fd = bpf_link_new_fd(link); if (fd < 0) |