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authorAndrii Nakryiko <andrii@kernel.org>2021-08-15 00:05:55 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2021-08-17 00:45:07 +0200
commit7d08c2c9117113fee118487425ed55efa50cbfa9 (patch)
treed7b87722b235a1f3dd5083d84ae7f9e4a3c1ee92
parentfb7dd8bca0139fd73d3f4a6cd257b11731317ded (diff)
bpf: Refactor BPF_PROG_RUN_ARRAY family of macros into functions
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. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20210815070609.987780-3-andrii@kernel.org
-rw-r--r--include/linux/bpf.h179
-rw-r--r--include/linux/filter.h5
-rw-r--r--kernel/bpf/cgroup.c32
-rw-r--r--kernel/trace/bpf_trace.c2
4 files changed, 124 insertions, 94 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 968fea98087a..344e0d4d8ef6 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1146,67 +1146,116 @@ 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;
};
+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;
+}
/* To be used by __cgroup_bpf_run_filter_skb for EGRESS BPF progs
* so BPF programs can request cwr for TCP packets.
@@ -1235,7 +1284,7 @@ _out: \
u32 _flags = 0; \
bool _cn; \
u32 _ret; \
- _ret = BPF_PROG_RUN_ARRAY_FLAGS(array, ctx, func, &_flags); \
+ _ret = BPF_PROG_RUN_ARRAY_CG_FLAGS(array, ctx, func, &_flags); \
_cn = _flags & BPF_RET_SET_CN; \
if (_ret) \
_ret = (_cn ? NET_XMIT_CN : NET_XMIT_SUCCESS); \
@@ -1244,12 +1293,6 @@ _out: \
_ret; \
})
-#define BPF_PROG_RUN_ARRAY(array, ctx, func) \
- __BPF_PROG_RUN_ARRAY(array, ctx, func, false, true)
-
-#define BPF_PROG_RUN_ARRAY_CHECK(array, ctx, func) \
- __BPF_PROG_RUN_ARRAY(array, ctx, func, true, false)
-
#ifdef CONFIG_BPF_SYSCALL
DECLARE_PER_CPU(int, bpf_prog_active);
extern struct mutex bpf_stats_enabled_mutex;
@@ -1284,20 +1327,6 @@ static inline void bpf_enable_instrumentation(void)
migrate_enable();
}
-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;
-}
-
extern const struct file_operations bpf_map_fops;
extern const struct file_operations bpf_prog_fops;
extern const struct file_operations bpf_iter_fops;
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 954373db20e7..7d248941ecea 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -723,7 +723,7 @@ static inline void bpf_restore_data_end(
cb->data_end = saved_data_end;
}
-static inline u8 *bpf_skb_cb(struct sk_buff *skb)
+static inline u8 *bpf_skb_cb(const struct sk_buff *skb)
{
/* eBPF programs may read/write skb->cb[] area to transfer meta
* data between tail calls. Since this also needs to work with
@@ -744,8 +744,9 @@ static inline u8 *bpf_skb_cb(struct sk_buff *skb)
/* Must be invoked with migration disabled */
static inline u32 __bpf_prog_run_save_cb(const struct bpf_prog *prog,
- struct sk_buff *skb)
+ const void *ctx)
{
+ const struct sk_buff *skb = ctx;
u8 *cb_data = bpf_skb_cb(skb);
u8 cb_saved[BPF_SKB_CB_LEN];
u32 res;
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 16dc467adfa0..a1dedba4c174 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -1012,8 +1012,8 @@ int __cgroup_bpf_run_filter_skb(struct sock *sk,
ret = BPF_PROG_CGROUP_INET_EGRESS_RUN_ARRAY(
cgrp->bpf.effective[type], skb, __bpf_prog_run_save_cb);
} else {
- ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], skb,
- __bpf_prog_run_save_cb);
+ ret = BPF_PROG_RUN_ARRAY_CG(cgrp->bpf.effective[type], skb,
+ __bpf_prog_run_save_cb);
ret = (ret == 1 ? 0 : -EPERM);
}
bpf_restore_data_end(skb, saved_data_end);
@@ -1043,7 +1043,7 @@ int __cgroup_bpf_run_filter_sk(struct sock *sk,
struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
int ret;
- ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], sk, bpf_prog_run);
+ ret = BPF_PROG_RUN_ARRAY_CG(cgrp->bpf.effective[type], sk, bpf_prog_run);
return ret == 1 ? 0 : -EPERM;
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sk);
@@ -1090,8 +1090,8 @@ int __cgroup_bpf_run_filter_sock_addr(struct sock *sk,
}
cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
- ret = BPF_PROG_RUN_ARRAY_FLAGS(cgrp->bpf.effective[type], &ctx,
- bpf_prog_run, flags);
+ ret = BPF_PROG_RUN_ARRAY_CG_FLAGS(cgrp->bpf.effective[type], &ctx,
+ bpf_prog_run, flags);
return ret == 1 ? 0 : -EPERM;
}
@@ -1120,8 +1120,8 @@ int __cgroup_bpf_run_filter_sock_ops(struct sock *sk,
struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
int ret;
- ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], sock_ops,
- bpf_prog_run);
+ ret = BPF_PROG_RUN_ARRAY_CG(cgrp->bpf.effective[type], sock_ops,
+ bpf_prog_run);
return ret == 1 ? 0 : -EPERM;
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sock_ops);
@@ -1139,8 +1139,8 @@ int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
rcu_read_lock();
cgrp = task_dfl_cgroup(current);
- allow = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], &ctx,
- bpf_prog_run);
+ allow = BPF_PROG_RUN_ARRAY_CG(cgrp->bpf.effective[type], &ctx,
+ bpf_prog_run);
rcu_read_unlock();
return !allow;
@@ -1271,7 +1271,7 @@ int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
rcu_read_lock();
cgrp = task_dfl_cgroup(current);
- ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], &ctx, bpf_prog_run);
+ ret = BPF_PROG_RUN_ARRAY_CG(cgrp->bpf.effective[type], &ctx, bpf_prog_run);
rcu_read_unlock();
kfree(ctx.cur_val);
@@ -1385,8 +1385,8 @@ int __cgroup_bpf_run_filter_setsockopt(struct sock *sk, int *level,
}
lock_sock(sk);
- ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[BPF_CGROUP_SETSOCKOPT],
- &ctx, bpf_prog_run);
+ ret = BPF_PROG_RUN_ARRAY_CG(cgrp->bpf.effective[BPF_CGROUP_SETSOCKOPT],
+ &ctx, bpf_prog_run);
release_sock(sk);
if (!ret) {
@@ -1495,8 +1495,8 @@ int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
}
lock_sock(sk);
- ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[BPF_CGROUP_GETSOCKOPT],
- &ctx, bpf_prog_run);
+ ret = BPF_PROG_RUN_ARRAY_CG(cgrp->bpf.effective[BPF_CGROUP_GETSOCKOPT],
+ &ctx, bpf_prog_run);
release_sock(sk);
if (!ret) {
@@ -1556,8 +1556,8 @@ int __cgroup_bpf_run_filter_getsockopt_kern(struct sock *sk, int level,
* be called if that data shouldn't be "exported".
*/
- ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[BPF_CGROUP_GETSOCKOPT],
- &ctx, bpf_prog_run);
+ ret = BPF_PROG_RUN_ARRAY_CG(cgrp->bpf.effective[BPF_CGROUP_GETSOCKOPT],
+ &ctx, bpf_prog_run);
if (!ret)
return -EPERM;
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 05a5a556671d..91867b14b222 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -124,7 +124,7 @@ unsigned int trace_call_bpf(struct trace_event_call *call, void *ctx)
* out of events when it was updated in between this and the
* rcu_dereference() which is accepted risk.
*/
- ret = BPF_PROG_RUN_ARRAY_CHECK(call->prog_array, ctx, bpf_prog_run);
+ ret = BPF_PROG_RUN_ARRAY(call->prog_array, ctx, bpf_prog_run);
out:
__this_cpu_dec(bpf_prog_active);

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