On 7/30/21 7:34 AM, Andrii Nakryiko wrote:
Similar to BPF_PROG_RUN, turn BPF_PROG_RUN_ARRAY macros into proper functions
with all the same readability and maintainability benefits. Making them into
functions required shuffling around bpf_set_run_ctx/bpf_reset_run_ctx
functions. Also, explicitly specifying the type of the BPF prog run callback
required adjusting __bpf_prog_run_save_cb() to accept const void *, casted
internally to const struct sk_buff.
Further, split out a cgroup-specific BPF_PROG_RUN_ARRAY_CG and
BPF_PROG_RUN_ARRAY_CG_FLAGS from the more generic BPF_PROG_RUN_ARRAY due to
the differences in bpf_run_ctx used for those two different use cases.
I think BPF_PROG_RUN_ARRAY_CG would benefit from further refactoring to accept
struct cgroup and enum bpf_attach_type instead of bpf_prog_array, fetching
cgrp->bpf.effective[type] and RCU-dereferencing it internally. But that
required including include/linux/cgroup-defs.h, which I wasn't sure is ok with
everyone.
The remaining generic BPF_PROG_RUN_ARRAY function will be extended to
pass-through user-provided context value in the next patch.
Acked-by: Yonghong Song <yhs@xxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
include/linux/bpf.h | 187 +++++++++++++++++++++++----------------
include/linux/filter.h | 5 +-
kernel/bpf/cgroup.c | 32 +++----
kernel/trace/bpf_trace.c | 2 +-
4 files changed, 132 insertions(+), 94 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index c8cc09013210..9c44b56b698f 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1146,67 +1146,124 @@ struct bpf_run_ctx {};
struct bpf_cg_run_ctx {
struct bpf_run_ctx run_ctx;
- struct bpf_prog_array_item *prog_item;
+ const struct bpf_prog_array_item *prog_item;
};
+#ifdef CONFIG_BPF_SYSCALL
+static inline struct bpf_run_ctx *bpf_set_run_ctx(struct bpf_run_ctx *new_ctx)
+{
+ struct bpf_run_ctx *old_ctx;
+
+ old_ctx = current->bpf_ctx;
+ current->bpf_ctx = new_ctx;
+ return old_ctx;
+}
+
+static inline void bpf_reset_run_ctx(struct bpf_run_ctx *old_ctx)
+{
+ current->bpf_ctx = old_ctx;
+}
+#else /* CONFIG_BPF_SYSCALL */
+static inline struct bpf_run_ctx *bpf_set_run_ctx(struct bpf_run_ctx *new_ctx)
+{
+ return NULL;
+}
+
+static inline void bpf_reset_run_ctx(struct bpf_run_ctx *old_ctx)
+{
+}
+#endif /* CONFIG_BPF_SYSCALL */
nit, but either is fine..:
static inline struct bpf_run_ctx *bpf_set_run_ctx(struct bpf_run_ctx *new_ctx)
{
struct bpf_run_ctx *old_ctx = NULL;
#ifdef CONFIG_BPF_SYSCALL
old_ctx = current->bpf_ctx;
current->bpf_ctx = new_ctx;
#endif
return old_ctx;
}
static inline void bpf_reset_run_ctx(struct bpf_run_ctx *old_ctx)
{
#ifdef CONFIG_BPF_SYSCALL
current->bpf_ctx = old_ctx;
#endif
}
/* BPF program asks to bypass CAP_NET_BIND_SERVICE in bind. */
#define BPF_RET_BIND_NO_CAP_NET_BIND_SERVICE (1 << 0)
/* BPF program asks to set CN on the packet. */
#define BPF_RET_SET_CN (1 << 0)
-#define BPF_PROG_RUN_ARRAY_FLAGS(array, ctx, func, ret_flags) \
- ({ \
- struct bpf_prog_array_item *_item; \
- struct bpf_prog *_prog; \
- struct bpf_prog_array *_array; \
- struct bpf_run_ctx *old_run_ctx; \
- struct bpf_cg_run_ctx run_ctx; \
- u32 _ret = 1; \
- u32 func_ret; \
- migrate_disable(); \
- rcu_read_lock(); \
- _array = rcu_dereference(array); \
- _item = &_array->items[0]; \
- old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx); \
- while ((_prog = READ_ONCE(_item->prog))) { \
- run_ctx.prog_item = _item; \
- func_ret = func(_prog, ctx); \
- _ret &= (func_ret & 1); \
- *(ret_flags) |= (func_ret >> 1); \
- _item++; \
- } \
- bpf_reset_run_ctx(old_run_ctx); \
- rcu_read_unlock(); \
- migrate_enable(); \
- _ret; \
- })
-
-#define __BPF_PROG_RUN_ARRAY(array, ctx, func, check_non_null, set_cg_storage) \
- ({ \
- struct bpf_prog_array_item *_item; \
- struct bpf_prog *_prog; \
- struct bpf_prog_array *_array; \
- struct bpf_run_ctx *old_run_ctx; \
- struct bpf_cg_run_ctx run_ctx; \
- u32 _ret = 1; \
- migrate_disable(); \
- rcu_read_lock(); \
- _array = rcu_dereference(array); \
- if (unlikely(check_non_null && !_array))\
- goto _out; \
- _item = &_array->items[0]; \
- old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx);\
- while ((_prog = READ_ONCE(_item->prog))) { \
- run_ctx.prog_item = _item; \
- _ret &= func(_prog, ctx); \
- _item++; \
- } \
- bpf_reset_run_ctx(old_run_ctx); \
-_out: \
- rcu_read_unlock(); \
- migrate_enable(); \
- _ret; \
- })
+typedef u32 (*bpf_prog_run_fn)(const struct bpf_prog *prog, const void *ctx);
+
+static __always_inline u32
+BPF_PROG_RUN_ARRAY_CG_FLAGS(const struct bpf_prog_array __rcu *array_rcu,
+ const void *ctx, bpf_prog_run_fn run_prog,
+ u32 *ret_flags)
+{
+ const struct bpf_prog_array_item *item;
+ const struct bpf_prog *prog;
+ const struct bpf_prog_array *array;
+ struct bpf_run_ctx *old_run_ctx;
+ struct bpf_cg_run_ctx run_ctx;
+ u32 ret = 1;
+ u32 func_ret;
+
+ migrate_disable();
+ rcu_read_lock();
+ array = rcu_dereference(array_rcu);
+ item = &array->items[0];
+ old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx);
+ while ((prog = READ_ONCE(item->prog))) {
+ run_ctx.prog_item = item;
+ func_ret = run_prog(prog, ctx);
+ ret &= (func_ret & 1);
+ *(ret_flags) |= (func_ret >> 1);
+ item++;
+ }
+ bpf_reset_run_ctx(old_run_ctx);
+ rcu_read_unlock();
+ migrate_enable();
+ return ret;
+}
+
+static __always_inline u32
+BPF_PROG_RUN_ARRAY_CG(const struct bpf_prog_array __rcu *array_rcu,
+ const void *ctx, bpf_prog_run_fn run_prog)
+{
+ const struct bpf_prog_array_item *item;
+ const struct bpf_prog *prog;
+ const struct bpf_prog_array *array;
+ struct bpf_run_ctx *old_run_ctx;
+ struct bpf_cg_run_ctx run_ctx;
+ u32 ret = 1;
+
+ migrate_disable();
+ rcu_read_lock();
+ array = rcu_dereference(array_rcu);
+ item = &array->items[0];
+ old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx);
+ while ((prog = READ_ONCE(item->prog))) {
+ run_ctx.prog_item = item;
+ ret &= run_prog(prog, ctx);
+ item++;
+ }
+ bpf_reset_run_ctx(old_run_ctx);
+ rcu_read_unlock();
+ migrate_enable();
+ return ret;
+}
+
+static __always_inline u32
+BPF_PROG_RUN_ARRAY(const struct bpf_prog_array __rcu *array_rcu,
+ const void *ctx, bpf_prog_run_fn run_prog)
+{
+ const struct bpf_prog_array_item *item;
+ const struct bpf_prog *prog;
+ const struct bpf_prog_array *array;
+ u32 ret = 1;
+
+ migrate_disable();
+ rcu_read_lock();
+ array = rcu_dereference(array_rcu);
+ if (unlikely(!array))
+ goto out;
+ item = &array->items[0];
+ while ((prog = READ_ONCE(item->prog))) {
+ ret &= run_prog(prog, ctx);
+ item++;
+ }
+out:
+ rcu_read_unlock();
+ migrate_enable();
+ return ret;
+}
Is there any way we could consolidate the above somewhat further and have things
optimized out at compilation time, e.g. when const args are null/non-null? :/
/* To be used by __cgroup_bpf_run_filter_skb for EGRESS BPF progs
* so BPF programs can request cwr for TCP packets.
@@ -1235,7 +1292,7 @@ _out: \
u32 _flags = 0; \
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