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Message-Id: <20220407223112.1204582-2-sdf@google.com>
Date: Thu, 7 Apr 2022 15:31:06 -0700
From: Stanislav Fomichev <sdf@...gle.com>
To: netdev@...r.kernel.org, bpf@...r.kernel.org
Cc: ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
Stanislav Fomichev <sdf@...gle.com>
Subject: [PATCH bpf-next v3 1/7] bpf: add bpf_func_t and trampoline helpers
I'll be adding lsm cgroup specific helpers that grab
trampoline mutex.
No functional changes.
Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
---
include/linux/bpf.h | 11 ++++---
kernel/bpf/trampoline.c | 63 +++++++++++++++++++++++------------------
2 files changed, 40 insertions(+), 34 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index bdb5298735ce..487aba40ce52 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -52,6 +52,8 @@ typedef u64 (*bpf_callback_t)(u64, u64, u64, u64, u64);
typedef int (*bpf_iter_init_seq_priv_t)(void *private_data,
struct bpf_iter_aux_info *aux);
typedef void (*bpf_iter_fini_seq_priv_t)(void *private_data);
+typedef unsigned int (*bpf_func_t)(const void *,
+ const struct bpf_insn *);
struct bpf_iter_seq_info {
const struct seq_operations *seq_ops;
bpf_iter_init_seq_priv_t init_seq_private;
@@ -798,8 +800,7 @@ struct bpf_dispatcher {
static __always_inline __nocfi unsigned int bpf_dispatcher_nop_func(
const void *ctx,
const struct bpf_insn *insnsi,
- unsigned int (*bpf_func)(const void *,
- const struct bpf_insn *))
+ bpf_func_t bpf_func)
{
return bpf_func(ctx, insnsi);
}
@@ -827,8 +828,7 @@ int arch_prepare_bpf_dispatcher(void *image, s64 *funcs, int num_funcs);
noinline __nocfi unsigned int bpf_dispatcher_##name##_func( \
const void *ctx, \
const struct bpf_insn *insnsi, \
- unsigned int (*bpf_func)(const void *, \
- const struct bpf_insn *)) \
+ bpf_func_t bpf_func) \
{ \
return bpf_func(ctx, insnsi); \
} \
@@ -839,8 +839,7 @@ int arch_prepare_bpf_dispatcher(void *image, s64 *funcs, int num_funcs);
unsigned int bpf_dispatcher_##name##_func( \
const void *ctx, \
const struct bpf_insn *insnsi, \
- unsigned int (*bpf_func)(const void *, \
- const struct bpf_insn *)); \
+ bpf_func_t bpf_func); \
extern struct bpf_dispatcher bpf_dispatcher_##name;
#define BPF_DISPATCHER_FUNC(name) bpf_dispatcher_##name##_func
#define BPF_DISPATCHER_PTR(name) (&bpf_dispatcher_##name)
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index ada97751ae1b..0c4fd194e801 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -407,42 +407,34 @@ static enum bpf_tramp_prog_type bpf_attach_type_to_tramp(struct bpf_prog *prog)
}
}
-int bpf_trampoline_link_prog(struct bpf_prog *prog, struct bpf_trampoline *tr)
+static int __bpf_trampoline_link_prog(struct bpf_prog *prog,
+ struct bpf_trampoline *tr)
{
enum bpf_tramp_prog_type kind;
int err = 0;
int cnt;
kind = bpf_attach_type_to_tramp(prog);
- mutex_lock(&tr->mutex);
- if (tr->extension_prog) {
+ if (tr->extension_prog)
/* cannot attach fentry/fexit if extension prog is attached.
* cannot overwrite extension prog either.
*/
- err = -EBUSY;
- goto out;
- }
+ return -EBUSY;
+
cnt = tr->progs_cnt[BPF_TRAMP_FENTRY] + tr->progs_cnt[BPF_TRAMP_FEXIT];
if (kind == BPF_TRAMP_REPLACE) {
/* Cannot attach extension if fentry/fexit are in use. */
- if (cnt) {
- err = -EBUSY;
- goto out;
- }
+ if (cnt)
+ return -EBUSY;
tr->extension_prog = prog;
- err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP, NULL,
- prog->bpf_func);
- goto out;
- }
- if (cnt >= BPF_MAX_TRAMP_PROGS) {
- err = -E2BIG;
- goto out;
+ return bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP, NULL,
+ prog->bpf_func);
}
- if (!hlist_unhashed(&prog->aux->tramp_hlist)) {
+ if (cnt >= BPF_MAX_TRAMP_PROGS)
+ return -E2BIG;
+ if (!hlist_unhashed(&prog->aux->tramp_hlist))
/* prog already linked */
- err = -EBUSY;
- goto out;
- }
+ return -EBUSY;
hlist_add_head(&prog->aux->tramp_hlist, &tr->progs_hlist[kind]);
tr->progs_cnt[kind]++;
err = bpf_trampoline_update(tr);
@@ -450,30 +442,45 @@ int bpf_trampoline_link_prog(struct bpf_prog *prog, struct bpf_trampoline *tr)
hlist_del_init(&prog->aux->tramp_hlist);
tr->progs_cnt[kind]--;
}
-out:
+ return err;
+}
+
+int bpf_trampoline_link_prog(struct bpf_prog *prog, struct bpf_trampoline *tr)
+{
+ int err;
+
+ mutex_lock(&tr->mutex);
+ err = __bpf_trampoline_link_prog(prog, tr);
mutex_unlock(&tr->mutex);
return err;
}
-/* bpf_trampoline_unlink_prog() should never fail. */
-int bpf_trampoline_unlink_prog(struct bpf_prog *prog, struct bpf_trampoline *tr)
+static int __bpf_trampoline_unlink_prog(struct bpf_prog *prog,
+ struct bpf_trampoline *tr)
{
enum bpf_tramp_prog_type kind;
int err;
kind = bpf_attach_type_to_tramp(prog);
- mutex_lock(&tr->mutex);
if (kind == BPF_TRAMP_REPLACE) {
WARN_ON_ONCE(!tr->extension_prog);
err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP,
tr->extension_prog->bpf_func, NULL);
tr->extension_prog = NULL;
- goto out;
+ return err;
}
hlist_del_init(&prog->aux->tramp_hlist);
tr->progs_cnt[kind]--;
- err = bpf_trampoline_update(tr);
-out:
+ return bpf_trampoline_update(tr);
+}
+
+/* bpf_trampoline_unlink_prog() should never fail. */
+int bpf_trampoline_unlink_prog(struct bpf_prog *prog, struct bpf_trampoline *tr)
+{
+ int err;
+
+ mutex_lock(&tr->mutex);
+ err = __bpf_trampoline_unlink_prog(prog, tr);
mutex_unlock(&tr->mutex);
return err;
}
--
2.35.1.1178.g4f1659d476-goog
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