net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.

The XDP redirect process is two staged:
- bpf_prog_run_xdp() is invoked to run a eBPF program which inspects the
  packet and makes decisions. While doing that, the per-CPU variable
  bpf_redirect_info is used.

- Afterwards xdp_do_redirect() is invoked and accesses bpf_redirect_info
  and it may also access other per-CPU variables like xskmap_flush_list.

At the very end of the NAPI callback, xdp_do_flush() is invoked which
does not access bpf_redirect_info but will touch the individual per-CPU
lists.

The per-CPU variables are only used in the NAPI callback hence disabling
bottom halves is the only protection mechanism. Users from preemptible
context (like cpu_map_kthread_run()) explicitly disable bottom halves
for protections reasons.
Without locking in local_bh_disable() on PREEMPT_RT this data structure
requires explicit locking.

PREEMPT_RT has forced-threaded interrupts enabled and every
NAPI-callback runs in a thread. If each thread has its own data
structure then locking can be avoided.

Create a struct bpf_net_context which contains struct bpf_redirect_info.
Define the variable on stack, use bpf_net_ctx_set() to save a pointer to
it, bpf_net_ctx_clear() removes it again.
The bpf_net_ctx_set() may nest. For instance a function can be used from
within NET_RX_SOFTIRQ/ net_rx_action which uses bpf_net_ctx_set() and
NET_TX_SOFTIRQ which does not. Therefore only the first invocations
updates the pointer.
Use bpf_net_ctx_get_ri() as a wrapper to retrieve the current struct
bpf_redirect_info. The returned data structure is zero initialized to
ensure nothing is leaked from stack. This is done on first usage of the
struct. bpf_net_ctx_set() sets bpf_redirect_info::kern_flags to 0 to
note that initialisation is required. First invocation of
bpf_net_ctx_get_ri() will memset() the data structure and update
bpf_redirect_info::kern_flags.
bpf_redirect_info::nh is excluded from memset because it is only used
once BPF_F_NEIGH is set which also sets the nh member. The kern_flags is
moved past nh to exclude it from memset.

The pointer to bpf_net_context is saved task's task_struct. Using
always the bpf_net_context approach has the advantage that there is
almost zero differences between PREEMPT_RT and non-PREEMPT_RT builds.

Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Song Liu <song@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-15-bigeasy@linutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/linux/filter.h b/include/linux/filter.h
index b02aea291b7e8ea22468d6a6ecb3e0c188dff026..0a7f6e4a00b603dec32a93615303189f40c6b765 100644 (file)
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -733,21 +733,59 @@ struct bpf_nh_params {
        };
 };
 
+/* flags for bpf_redirect_info kern_flags */
+#define BPF_RI_F_RF_NO_DIRECT  BIT(0)  /* no napi_direct on return_frame */
+#define BPF_RI_F_RI_INIT       BIT(1)
+
 struct bpf_redirect_info {
        u64 tgt_index;
        void *tgt_value;
        struct bpf_map *map;
        u32 flags;
-       u32 kern_flags;
        u32 map_id;
        enum bpf_map_type map_type;
        struct bpf_nh_params nh;
+       u32 kern_flags;
 };
 
-DECLARE_PER_CPU(struct bpf_redirect_info, bpf_redirect_info);
+struct bpf_net_context {
+       struct bpf_redirect_info ri;
+};
 
-/* flags for bpf_redirect_info kern_flags */
-#define BPF_RI_F_RF_NO_DIRECT  BIT(0)  /* no napi_direct on return_frame */
+static inline struct bpf_net_context *bpf_net_ctx_set(struct bpf_net_context *bpf_net_ctx)
+{
+       struct task_struct *tsk = current;
+
+       if (tsk->bpf_net_context != NULL)
+               return NULL;
+       bpf_net_ctx->ri.kern_flags = 0;
+
+       tsk->bpf_net_context = bpf_net_ctx;
+       return bpf_net_ctx;
+}
+
+static inline void bpf_net_ctx_clear(struct bpf_net_context *bpf_net_ctx)
+{
+       if (bpf_net_ctx)
+               current->bpf_net_context = NULL;
+}
+
+static inline struct bpf_net_context *bpf_net_ctx_get(void)
+{
+       return current->bpf_net_context;
+}
+
+static inline struct bpf_redirect_info *bpf_net_ctx_get_ri(void)
+{
+       struct bpf_net_context *bpf_net_ctx = bpf_net_ctx_get();
+
+       if (!(bpf_net_ctx->ri.kern_flags & BPF_RI_F_RI_INIT)) {
+               memset(&bpf_net_ctx->ri, 0, offsetof(struct bpf_net_context, ri.nh));
+               bpf_net_ctx->ri.kern_flags |= BPF_RI_F_RI_INIT;
+       }
+
+       return &bpf_net_ctx->ri;
+}
 
 /* Compute the linear packet data range [data, data_end) which
  * will be accessed by various program types (cls_bpf, act_bpf,
@@ -1018,25 +1056,23 @@ struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,
                                       const struct bpf_insn *patch, u32 len);
 int bpf_remove_insns(struct bpf_prog *prog, u32 off, u32 cnt);
 
-void bpf_clear_redirect_map(struct bpf_map *map);
-
 static inline bool xdp_return_frame_no_direct(void)
 {
-       struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
+       struct bpf_redirect_info *ri = bpf_net_ctx_get_ri();
 
        return ri->kern_flags & BPF_RI_F_RF_NO_DIRECT;
 }
 
 static inline void xdp_set_return_frame_no_direct(void)
 {
-       struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
+       struct bpf_redirect_info *ri = bpf_net_ctx_get_ri();
 
        ri->kern_flags |= BPF_RI_F_RF_NO_DIRECT;
 }
 
 static inline void xdp_clear_return_frame_no_direct(void)
 {
-       struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
+       struct bpf_redirect_info *ri = bpf_net_ctx_get_ri();
 
        ri->kern_flags &= ~BPF_RI_F_RF_NO_DIRECT;
 }
@@ -1592,7 +1628,7 @@ static __always_inline long __bpf_xdp_redirect_map(struct bpf_map *map, u64 inde
                                                   u64 flags, const u64 flag_mask,
                                                   void *lookup_elem(struct bpf_map *map, u32 key))
 {
-       struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
+       struct bpf_redirect_info *ri = bpf_net_ctx_get_ri();
        const u64 action_mask = XDP_ABORTED | XDP_DROP | XDP_PASS | XDP_TX;
 
        /* Lower bits of the flags are used as return code on lookup failure */

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 5187486c25222d0c8abfe86063133653567b2613..5ff5e65a4627725e7ff62e9beb8d8dabd9fb559d 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -54,6 +54,7 @@ struct bio_list;
 struct blk_plug;
 struct bpf_local_storage;
 struct bpf_run_ctx;
+struct bpf_net_context;
 struct capture_control;
 struct cfs_rq;
 struct fs_struct;
@@ -1509,6 +1510,8 @@ struct task_struct {
        /* Used for BPF run context */
        struct bpf_run_ctx              *bpf_ctx;
 #endif
+       /* Used by BPF for per-TASK xdp storage */
+       struct bpf_net_context          *bpf_net_context;
 
 #ifdef CONFIG_GCC_PLUGIN_STACKLEAK
        unsigned long                   lowest_stack;

diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c
index a8e34416e960f5c89d90e0e2981154aa206bac42..66974bd0271092e875f970d4b1eeda4cd1e72562 100644 (file)
--- a/kernel/bpf/cpumap.c
+++ b/kernel/bpf/cpumap.c
@@ -240,12 +240,14 @@ static int cpu_map_bpf_prog_run(struct bpf_cpu_map_entry *rcpu, void **frames,
                                int xdp_n, struct xdp_cpumap_stats *stats,
                                struct list_head *list)
 {
+       struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx;
        int nframes;
 
        if (!rcpu->prog)
                return xdp_n;
 
        rcu_read_lock_bh();
+       bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx);
 
        nframes = cpu_map_bpf_prog_run_xdp(rcpu, frames, xdp_n, stats);
 
@@ -255,6 +257,7 @@ static int cpu_map_bpf_prog_run(struct bpf_cpu_map_entry *rcpu, void **frames,
        if (unlikely(!list_empty(list)))
                cpu_map_bpf_prog_run_skb(rcpu, list, stats);
 
+       bpf_net_ctx_clear(bpf_net_ctx);
        rcu_read_unlock_bh(); /* resched point, may call do_softirq() */
 
        return nframes;

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index 7f3b34452243c83b6e113b5a5d831fc088854f54..fbfdfb60db8d75fddc5a043ac60c1b9f778bab49 100644 (file)
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -196,7 +196,14 @@ static void dev_map_free(struct bpf_map *map)
        list_del_rcu(&dtab->list);
        spin_unlock(&dev_map_lock);
 
-       bpf_clear_redirect_map(map);
+       /* bpf_redirect_info->map is assigned in __bpf_xdp_redirect_map()
+        * during NAPI callback and cleared after the XDP redirect. There is no
+        * explicit RCU read section which protects bpf_redirect_info->map but
+        * local_bh_disable() also marks the beginning an RCU section. This
+        * makes the complete softirq callback RCU protected. Thus after
+        * following synchronize_rcu() there no bpf_redirect_info->map == map
+        * assignment.
+        */
        synchronize_rcu();
 
        /* Make sure prior __dev_map_entry_free() have completed. */

diff --git a/kernel/fork.c b/kernel/fork.c
index 99076dbe27d83f93d704882d4f5c09ae103af303..f314bdd7e6108abff0c5c174bf19926f2ebee04c 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2355,6 +2355,7 @@ __latent_entropy struct task_struct *copy_process(
        RCU_INIT_POINTER(p->bpf_storage, NULL);
        p->bpf_ctx = NULL;
 #endif
+       p->bpf_net_context =  NULL;
 
        /* Perform scheduler related setup. Assign this task to a CPU. */
        retval = sched_fork(clone_flags, p);

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 36ae54f57bf5743b37c5c785baa7c4aa8e871024..a6d7f790cdda8635187c05608e0e653ceedf0f2d 100644 (file)
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -283,9 +283,10 @@ static int xdp_recv_frames(struct xdp_frame **frames, int nframes,
 static int xdp_test_run_batch(struct xdp_test_data *xdp, struct bpf_prog *prog,
                              u32 repeat)
 {
-       struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
+       struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx;
        int err = 0, act, ret, i, nframes = 0, batch_sz;
        struct xdp_frame **frames = xdp->frames;
+       struct bpf_redirect_info *ri;
        struct xdp_page_head *head;
        struct xdp_frame *frm;
        bool redirect = false;
@@ -295,6 +296,8 @@ static int xdp_test_run_batch(struct xdp_test_data *xdp, struct bpf_prog *prog,
        batch_sz = min_t(u32, repeat, xdp->batch_size);
 
        local_bh_disable();
+       bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx);
+       ri = bpf_net_ctx_get_ri();
        xdp_set_return_frame_no_direct();
 
        for (i = 0; i < batch_sz; i++) {
@@ -359,6 +362,7 @@ out:
        }
 
        xdp_clear_return_frame_no_direct();
+       bpf_net_ctx_clear(bpf_net_ctx);
        local_bh_enable();
        return err;
 }
@@ -394,6 +398,7 @@ static int bpf_test_run_xdp_live(struct bpf_prog *prog, struct xdp_buff *ctx,
 static int bpf_test_run(struct bpf_prog *prog, void *ctx, u32 repeat,
                        u32 *retval, u32 *time, bool xdp)
 {
+       struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx;
        struct bpf_prog_array_item item = {.prog = prog};
        struct bpf_run_ctx *old_ctx;
        struct bpf_cg_run_ctx run_ctx;
@@ -419,10 +424,14 @@ static int bpf_test_run(struct bpf_prog *prog, void *ctx, u32 repeat,
        do {
                run_ctx.prog_item = &item;
                local_bh_disable();
+               bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx);
+
                if (xdp)
                        *retval = bpf_prog_run_xdp(prog, ctx);
                else
                        *retval = bpf_prog_run(prog, ctx);
+
+               bpf_net_ctx_clear(bpf_net_ctx);
                local_bh_enable();
        } while (bpf_test_timer_continue(&t, 1, repeat, &ret, time));
        bpf_reset_run_ctx(old_ctx);

diff --git a/net/core/dev.c b/net/core/dev.c
index 8ef727c2ae2be503fbfb9f49eb29b818cf94fe0c..b94fb4e63a2897455972bc478290b4022d0b5608 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4045,10 +4045,13 @@ sch_handle_ingress(struct sk_buff *skb, struct packet_type **pt_prev, int *ret,
 {
        struct bpf_mprog_entry *entry = rcu_dereference_bh(skb->dev->tcx_ingress);
        enum skb_drop_reason drop_reason = SKB_DROP_REASON_TC_INGRESS;
+       struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx;
        int sch_ret;
 
        if (!entry)
                return skb;
+
+       bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx);
        if (*pt_prev) {
                *ret = deliver_skb(skb, *pt_prev, orig_dev);
                *pt_prev = NULL;
@@ -4077,10 +4080,12 @@ ingress_verdict:
                        break;
                }
                *ret = NET_RX_SUCCESS;
+               bpf_net_ctx_clear(bpf_net_ctx);
                return NULL;
        case TC_ACT_SHOT:
                kfree_skb_reason(skb, drop_reason);
                *ret = NET_RX_DROP;
+               bpf_net_ctx_clear(bpf_net_ctx);
                return NULL;
        /* used by tc_run */
        case TC_ACT_STOLEN:
@@ -4090,8 +4095,10 @@ ingress_verdict:
                fallthrough;
        case TC_ACT_CONSUMED:
                *ret = NET_RX_SUCCESS;
+               bpf_net_ctx_clear(bpf_net_ctx);
                return NULL;
        }
+       bpf_net_ctx_clear(bpf_net_ctx);
 
        return skb;
 }
@@ -4101,11 +4108,14 @@ sch_handle_egress(struct sk_buff *skb, int *ret, struct net_device *dev)
 {
        struct bpf_mprog_entry *entry = rcu_dereference_bh(dev->tcx_egress);
        enum skb_drop_reason drop_reason = SKB_DROP_REASON_TC_EGRESS;
+       struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx;
        int sch_ret;
 
        if (!entry)
                return skb;
 
+       bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx);
+
        /* qdisc_skb_cb(skb)->pkt_len & tcx_set_ingress() was
         * already set by the caller.
         */
@@ -4121,10 +4131,12 @@ egress_verdict:
                /* No need to push/pop skb's mac_header here on egress! */
                skb_do_redirect(skb);
                *ret = NET_XMIT_SUCCESS;
+               bpf_net_ctx_clear(bpf_net_ctx);
                return NULL;
        case TC_ACT_SHOT:
                kfree_skb_reason(skb, drop_reason);
                *ret = NET_XMIT_DROP;
+               bpf_net_ctx_clear(bpf_net_ctx);
                return NULL;
        /* used by tc_run */
        case TC_ACT_STOLEN:
@@ -4134,8 +4146,10 @@ egress_verdict:
                fallthrough;
        case TC_ACT_CONSUMED:
                *ret = NET_XMIT_SUCCESS;
+               bpf_net_ctx_clear(bpf_net_ctx);
                return NULL;
        }
+       bpf_net_ctx_clear(bpf_net_ctx);
 
        return skb;
 }
@@ -6325,6 +6339,7 @@ enum {
 static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock,
                           unsigned flags, u16 budget)
 {
+       struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx;
        bool skip_schedule = false;
        unsigned long timeout;
        int rc;
@@ -6342,6 +6357,7 @@ static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock,
        clear_bit(NAPI_STATE_IN_BUSY_POLL, &napi->state);
 
        local_bh_disable();
+       bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx);
 
        if (flags & NAPI_F_PREFER_BUSY_POLL) {
                napi->defer_hard_irqs_count = READ_ONCE(napi->dev->napi_defer_hard_irqs);
@@ -6364,6 +6380,7 @@ static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock,
        netpoll_poll_unlock(have_poll_lock);
        if (rc == budget)
                __busy_poll_stop(napi, skip_schedule);
+       bpf_net_ctx_clear(bpf_net_ctx);
        local_bh_enable();
 }
 
@@ -6373,6 +6390,7 @@ static void __napi_busy_loop(unsigned int napi_id,
 {
        unsigned long start_time = loop_end ? busy_loop_current_time() : 0;
        int (*napi_poll)(struct napi_struct *napi, int budget);
+       struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx;
        void *have_poll_lock = NULL;
        struct napi_struct *napi;
 
@@ -6391,6 +6409,7 @@ restart:
                int work = 0;
 
                local_bh_disable();
+               bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx);
                if (!napi_poll) {
                        unsigned long val = READ_ONCE(napi->state);
 
@@ -6421,6 +6440,7 @@ count:
                        __NET_ADD_STATS(dev_net(napi->dev),
                                        LINUX_MIB_BUSYPOLLRXPACKETS, work);
                skb_defer_free_flush(this_cpu_ptr(&softnet_data));
+               bpf_net_ctx_clear(bpf_net_ctx);
                local_bh_enable();
 
                if (!loop_end || loop_end(loop_end_arg, start_time))
@@ -6848,6 +6868,7 @@ static int napi_thread_wait(struct napi_struct *napi)
 
 static void napi_threaded_poll_loop(struct napi_struct *napi)
 {
+       struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx;
        struct softnet_data *sd;
        unsigned long last_qs = jiffies;
 
@@ -6856,6 +6877,8 @@ static void napi_threaded_poll_loop(struct napi_struct *napi)
                void *have;
 
                local_bh_disable();
+               bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx);
+
                sd = this_cpu_ptr(&softnet_data);
                sd->in_napi_threaded_poll = true;
 
@@ -6871,6 +6894,7 @@ static void napi_threaded_poll_loop(struct napi_struct *napi)
                        net_rps_action_and_irq_enable(sd);
                }
                skb_defer_free_flush(sd);
+               bpf_net_ctx_clear(bpf_net_ctx);
                local_bh_enable();
 
                if (!repoll)
@@ -6896,10 +6920,12 @@ static __latent_entropy void net_rx_action(struct softirq_action *h)
        struct softnet_data *sd = this_cpu_ptr(&softnet_data);
        unsigned long time_limit = jiffies +
                usecs_to_jiffies(READ_ONCE(net_hotdata.netdev_budget_usecs));
+       struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx;
        int budget = READ_ONCE(net_hotdata.netdev_budget);
        LIST_HEAD(list);
        LIST_HEAD(repoll);
 
+       bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx);
 start:
        sd->in_net_rx_action = true;
        local_irq_disable();
@@ -6952,7 +6978,8 @@ start:
                sd->in_net_rx_action = false;
 
        net_rps_action_and_irq_enable(sd);
-end:;
+end:
+       bpf_net_ctx_clear(bpf_net_ctx);
 }
 
 struct netdev_adjacent {

diff --git a/net/core/filter.c b/net/core/filter.c
index adb887195c3a4a6be6dbb32b0976f51687fafd48..eb1c4425c06f3cbef4615d280f702399cdd48a6e 100644 (file)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2483,9 +2483,6 @@ static const struct bpf_func_proto bpf_clone_redirect_proto = {
        .arg3_type      = ARG_ANYTHING,
 };
 
-DEFINE_PER_CPU(struct bpf_redirect_info, bpf_redirect_info);
-EXPORT_PER_CPU_SYMBOL_GPL(bpf_redirect_info);
-
 static struct net_device *skb_get_peer_dev(struct net_device *dev)
 {
        const struct net_device_ops *ops = dev->netdev_ops;
@@ -2498,7 +2495,7 @@ static struct net_device *skb_get_peer_dev(struct net_device *dev)
 
 int skb_do_redirect(struct sk_buff *skb)
 {
-       struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
+       struct bpf_redirect_info *ri = bpf_net_ctx_get_ri();
        struct net *net = dev_net(skb->dev);
        struct net_device *dev;
        u32 flags = ri->flags;
@@ -2531,7 +2528,7 @@ out_drop:
 
 BPF_CALL_2(bpf_redirect, u32, ifindex, u64, flags)
 {
-       struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
+       struct bpf_redirect_info *ri = bpf_net_ctx_get_ri();
 
        if (unlikely(flags & (~(BPF_F_INGRESS) | BPF_F_REDIRECT_INTERNAL)))
                return TC_ACT_SHOT;
@@ -2552,7 +2549,7 @@ static const struct bpf_func_proto bpf_redirect_proto = {
 
 BPF_CALL_2(bpf_redirect_peer, u32, ifindex, u64, flags)
 {
-       struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
+       struct bpf_redirect_info *ri = bpf_net_ctx_get_ri();
 
        if (unlikely(flags))
                return TC_ACT_SHOT;
@@ -2574,7 +2571,7 @@ static const struct bpf_func_proto bpf_redirect_peer_proto = {
 BPF_CALL_4(bpf_redirect_neigh, u32, ifindex, struct bpf_redir_neigh *, params,
           int, plen, u64, flags)
 {
-       struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
+       struct bpf_redirect_info *ri = bpf_net_ctx_get_ri();
 
        if (unlikely((plen && plen < sizeof(*params)) || flags))
                return TC_ACT_SHOT;
@@ -4300,30 +4297,13 @@ void xdp_do_check_flushed(struct napi_struct *napi)
 }
 #endif
 
-void bpf_clear_redirect_map(struct bpf_map *map)
-{
-       struct bpf_redirect_info *ri;
-       int cpu;
-
-       for_each_possible_cpu(cpu) {
-               ri = per_cpu_ptr(&bpf_redirect_info, cpu);
-               /* Avoid polluting remote cacheline due to writes if
-                * not needed. Once we pass this test, we need the
-                * cmpxchg() to make sure it hasn't been changed in
-                * the meantime by remote CPU.
-                */
-               if (unlikely(READ_ONCE(ri->map) == map))
-                       cmpxchg(&ri->map, map, NULL);
-       }
-}
-
 DEFINE_STATIC_KEY_FALSE(bpf_master_redirect_enabled_key);
 EXPORT_SYMBOL_GPL(bpf_master_redirect_enabled_key);
 
 u32 xdp_master_redirect(struct xdp_buff *xdp)
 {
+       struct bpf_redirect_info *ri = bpf_net_ctx_get_ri();
        struct net_device *master, *slave;
-       struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
 
        master = netdev_master_upper_dev_get_rcu(xdp->rxq->dev);
        slave = master->netdev_ops->ndo_xdp_get_xmit_slave(master, xdp);
@@ -4395,7 +4375,7 @@ static __always_inline int __xdp_do_redirect_frame(struct bpf_redirect_info *ri,
                        map = READ_ONCE(ri->map);
 
                        /* The map pointer is cleared when the map is being torn
-                        * down by bpf_clear_redirect_map()
+                        * down by dev_map_free()
                         */
                        if (unlikely(!map)) {
                                err = -ENOENT;
@@ -4440,7 +4420,7 @@ err:
 int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
                    struct bpf_prog *xdp_prog)
 {
-       struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
+       struct bpf_redirect_info *ri = bpf_net_ctx_get_ri();
        enum bpf_map_type map_type = ri->map_type;
 
        if (map_type == BPF_MAP_TYPE_XSKMAP)
@@ -4454,7 +4434,7 @@ EXPORT_SYMBOL_GPL(xdp_do_redirect);
 int xdp_do_redirect_frame(struct net_device *dev, struct xdp_buff *xdp,
                          struct xdp_frame *xdpf, struct bpf_prog *xdp_prog)
 {
-       struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
+       struct bpf_redirect_info *ri = bpf_net_ctx_get_ri();
        enum bpf_map_type map_type = ri->map_type;
 
        if (map_type == BPF_MAP_TYPE_XSKMAP)
@@ -4471,7 +4451,7 @@ static int xdp_do_generic_redirect_map(struct net_device *dev,
                                       enum bpf_map_type map_type, u32 map_id,
                                       u32 flags)
 {
-       struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
+       struct bpf_redirect_info *ri = bpf_net_ctx_get_ri();
        struct bpf_map *map;
        int err;
 
@@ -4483,7 +4463,7 @@ static int xdp_do_generic_redirect_map(struct net_device *dev,
                        map = READ_ONCE(ri->map);
 
                        /* The map pointer is cleared when the map is being torn
-                        * down by bpf_clear_redirect_map()
+                        * down by dev_map_free()
                         */
                        if (unlikely(!map)) {
                                err = -ENOENT;
@@ -4525,7 +4505,7 @@ err:
 int xdp_do_generic_redirect(struct net_device *dev, struct sk_buff *skb,
                            struct xdp_buff *xdp, struct bpf_prog *xdp_prog)
 {
-       struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
+       struct bpf_redirect_info *ri = bpf_net_ctx_get_ri();
        enum bpf_map_type map_type = ri->map_type;
        void *fwd = ri->tgt_value;
        u32 map_id = ri->map_id;
@@ -4561,7 +4541,7 @@ err:
 
 BPF_CALL_2(bpf_xdp_redirect, u32, ifindex, u64, flags)
 {
-       struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
+       struct bpf_redirect_info *ri = bpf_net_ctx_get_ri();
 
        if (unlikely(flags))
                return XDP_ABORTED;

diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c
index a94943681e5aa6bffd9b62f77953292dd4e1bcf6..afb05f58b64c54af323444ec38b3de9e2fb1692f 100644 (file)
--- a/net/core/lwt_bpf.c
+++ b/net/core/lwt_bpf.c
@@ -38,12 +38,14 @@ static inline struct bpf_lwt *bpf_lwt_lwtunnel(struct lwtunnel_state *lwt)
 static int run_lwt_bpf(struct sk_buff *skb, struct bpf_lwt_prog *lwt,
                       struct dst_entry *dst, bool can_redirect)
 {
+       struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx;
        int ret;
 
        /* Disabling BH is needed to protect per-CPU bpf_redirect_info between
         * BPF prog and skb_do_redirect().
         */
        local_bh_disable();
+       bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx);
        bpf_compute_data_pointers(skb);
        ret = bpf_prog_run_save_cb(lwt->prog, skb);
 
@@ -76,6 +78,7 @@ static int run_lwt_bpf(struct sk_buff *skb, struct bpf_lwt_prog *lwt,
                break;
        }
 
+       bpf_net_ctx_clear(bpf_net_ctx);
        local_bh_enable();
 
        return ret;