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Message-Id: <20190508171845.201303-2-sdf@google.com>
Date: Wed, 8 May 2019 10:18:42 -0700
From: Stanislav Fomichev <sdf@...gle.com>
To: netdev@...r.kernel.org, bpf@...r.kernel.org
Cc: davem@...emloft.net, ast@...nel.org, daniel@...earbox.net,
Stanislav Fomichev <sdf@...gle.com>
Subject: [PATCH bpf 1/4] bpf: remove __rcu annotations from bpf_prog_array
Drop __rcu annotations and rcu read sections. That's not needed since
all existing callers call those helpers from the rcu update side
and under a mutex. This guarantees that use-after-free could not
happen. In the next patches I'll fix the callers with missing
rcu_dereference_protected to make sparse/lockdep happy.
Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
---
include/linux/bpf.h | 12 ++++++------
kernel/bpf/core.c | 31 ++++++++++++-------------------
2 files changed, 18 insertions(+), 25 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 944ccc310201..b90d2859bc60 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -476,17 +476,17 @@ struct bpf_prog_array {
};
struct bpf_prog_array *bpf_prog_array_alloc(u32 prog_cnt, gfp_t flags);
-void bpf_prog_array_free(struct bpf_prog_array __rcu *progs);
-int bpf_prog_array_length(struct bpf_prog_array __rcu *progs);
-int bpf_prog_array_copy_to_user(struct bpf_prog_array __rcu *progs,
+void bpf_prog_array_free(struct bpf_prog_array *progs);
+int bpf_prog_array_length(struct bpf_prog_array *progs);
+int bpf_prog_array_copy_to_user(struct bpf_prog_array *progs,
__u32 __user *prog_ids, u32 cnt);
-void bpf_prog_array_delete_safe(struct bpf_prog_array __rcu *progs,
+void bpf_prog_array_delete_safe(struct bpf_prog_array *progs,
struct bpf_prog *old_prog);
-int bpf_prog_array_copy_info(struct bpf_prog_array __rcu *array,
+int bpf_prog_array_copy_info(struct bpf_prog_array *array,
u32 *prog_ids, u32 request_cnt,
u32 *prog_cnt);
-int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array,
+int bpf_prog_array_copy(struct bpf_prog_array *old_array,
struct bpf_prog *exclude_prog,
struct bpf_prog *include_prog,
struct bpf_prog_array **new_array);
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index ff09d32a8a1b..da03fbc811fd 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1794,38 +1794,33 @@ struct bpf_prog_array *bpf_prog_array_alloc(u32 prog_cnt, gfp_t flags)
return &empty_prog_array.hdr;
}
-void bpf_prog_array_free(struct bpf_prog_array __rcu *progs)
+void bpf_prog_array_free(struct bpf_prog_array *progs)
{
- if (!progs ||
- progs == (struct bpf_prog_array __rcu *)&empty_prog_array.hdr)
+ if (!progs || progs == &empty_prog_array.hdr)
return;
kfree_rcu(progs, rcu);
}
-int bpf_prog_array_length(struct bpf_prog_array __rcu *array)
+int bpf_prog_array_length(struct bpf_prog_array *array)
{
struct bpf_prog_array_item *item;
u32 cnt = 0;
- rcu_read_lock();
- item = rcu_dereference(array)->items;
- for (; item->prog; item++)
+ for (item = array->items; item->prog; item++)
if (item->prog != &dummy_bpf_prog.prog)
cnt++;
- rcu_read_unlock();
return cnt;
}
-static bool bpf_prog_array_copy_core(struct bpf_prog_array __rcu *array,
+static bool bpf_prog_array_copy_core(struct bpf_prog_array *array,
u32 *prog_ids,
u32 request_cnt)
{
struct bpf_prog_array_item *item;
int i = 0;
- item = rcu_dereference_check(array, 1)->items;
- for (; item->prog; item++) {
+ for (item = array->items; item->prog; item++) {
if (item->prog == &dummy_bpf_prog.prog)
continue;
prog_ids[i] = item->prog->aux->id;
@@ -1838,7 +1833,7 @@ static bool bpf_prog_array_copy_core(struct bpf_prog_array __rcu *array,
return !!(item->prog);
}
-int bpf_prog_array_copy_to_user(struct bpf_prog_array __rcu *array,
+int bpf_prog_array_copy_to_user(struct bpf_prog_array *array,
__u32 __user *prog_ids, u32 cnt)
{
unsigned long err = 0;
@@ -1858,9 +1853,7 @@ int bpf_prog_array_copy_to_user(struct bpf_prog_array __rcu *array,
ids = kcalloc(cnt, sizeof(u32), GFP_USER | __GFP_NOWARN);
if (!ids)
return -ENOMEM;
- rcu_read_lock();
nospc = bpf_prog_array_copy_core(array, ids, cnt);
- rcu_read_unlock();
err = copy_to_user(prog_ids, ids, cnt * sizeof(u32));
kfree(ids);
if (err)
@@ -1870,19 +1863,19 @@ int bpf_prog_array_copy_to_user(struct bpf_prog_array __rcu *array,
return 0;
}
-void bpf_prog_array_delete_safe(struct bpf_prog_array __rcu *array,
+void bpf_prog_array_delete_safe(struct bpf_prog_array *array,
struct bpf_prog *old_prog)
{
- struct bpf_prog_array_item *item = array->items;
+ struct bpf_prog_array_item *item;
- for (; item->prog; item++)
+ for (item = array->items; item->prog; item++)
if (item->prog == old_prog) {
WRITE_ONCE(item->prog, &dummy_bpf_prog.prog);
break;
}
}
-int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array,
+int bpf_prog_array_copy(struct bpf_prog_array *old_array,
struct bpf_prog *exclude_prog,
struct bpf_prog *include_prog,
struct bpf_prog_array **new_array)
@@ -1946,7 +1939,7 @@ int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array,
return 0;
}
-int bpf_prog_array_copy_info(struct bpf_prog_array __rcu *array,
+int bpf_prog_array_copy_info(struct bpf_prog_array *array,
u32 *prog_ids, u32 request_cnt,
u32 *prog_cnt)
{
--
2.21.0.1020.gf2820cf01a-goog
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