ebpf: misc core cleanup

Besides others, move bpf_tail_call_proto to the remaining definitions
of other protos, improve comments a bit (i.e. remove some obvious ones,
where the code is already self-documenting, add objectives for others),
simplify bpf_prog_array_compatible() a bit.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 4548422..1e00aa3 100644 (file)
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -26,9 +26,10 @@
 #include <linux/vmalloc.h>
 #include <linux/random.h>
 #include <linux/moduleloader.h>
-#include <asm/unaligned.h>
 #include <linux/bpf.h>
 
+#include <asm/unaligned.h>
+
 /* Registers */
 #define BPF_R0 regs[BPF_REG_0]
 #define BPF_R1 regs[BPF_REG_1]
@@ -62,6 +63,7 @@ void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb, int k, uns
                ptr = skb_network_header(skb) + k - SKF_NET_OFF;
        else if (k >= SKF_LL_OFF)
                ptr = skb_mac_header(skb) + k - SKF_LL_OFF;
+
        if (ptr >= skb->head && ptr + size <= skb_tail_pointer(skb))
                return ptr;
 
@@ -176,15 +178,6 @@ noinline u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
        return 0;
 }
 
-const struct bpf_func_proto bpf_tail_call_proto = {
-       .func = NULL,
-       .gpl_only = false,
-       .ret_type = RET_VOID,
-       .arg1_type = ARG_PTR_TO_CTX,
-       .arg2_type = ARG_CONST_MAP_PTR,
-       .arg3_type = ARG_ANYTHING,
-};
-
 /**
  *     __bpf_prog_run - run eBPF program on a given context
  *     @ctx: is the data we are operating on
@@ -650,36 +643,35 @@ load_byte:
                return 0;
 }
 
-void __weak bpf_int_jit_compile(struct bpf_prog *prog)
-{
-}
-
-bool bpf_prog_array_compatible(struct bpf_array *array, const struct bpf_prog *fp)
+bool bpf_prog_array_compatible(struct bpf_array *array,
+                              const struct bpf_prog *fp)
 {
-       if (array->owner_prog_type) {
-               if (array->owner_prog_type != fp->type)
-                       return false;
-               if (array->owner_jited != fp->jited)
-                       return false;
-       } else {
+       if (!array->owner_prog_type) {
+               /* There's no owner yet where we could check for
+                * compatibility.
+                */
                array->owner_prog_type = fp->type;
                array->owner_jited = fp->jited;
+
+               return true;
        }
-       return true;
+
+       return array->owner_prog_type == fp->type &&
+              array->owner_jited == fp->jited;
 }
 
-static int check_tail_call(const struct bpf_prog *fp)
+static int bpf_check_tail_call(const struct bpf_prog *fp)
 {
        struct bpf_prog_aux *aux = fp->aux;
        int i;
 
        for (i = 0; i < aux->used_map_cnt; i++) {
+               struct bpf_map *map = aux->used_maps[i];
                struct bpf_array *array;
-               struct bpf_map *map;
 
-               map = aux->used_maps[i];
                if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
                        continue;
+
                array = container_of(map, struct bpf_array, map);
                if (!bpf_prog_array_compatible(array, fp))
                        return -EINVAL;
@@ -689,22 +681,25 @@ static int check_tail_call(const struct bpf_prog *fp)
 }
 
 /**
- *     bpf_prog_select_runtime - select execution runtime for BPF program
+ *     bpf_prog_select_runtime - select exec runtime for BPF program
  *     @fp: bpf_prog populated with internal BPF program
  *
- * try to JIT internal BPF program, if JIT is not available select interpreter
- * BPF program will be executed via BPF_PROG_RUN() macro
+ * Try to JIT eBPF program, if JIT is not available, use interpreter.
+ * The BPF program will be executed via BPF_PROG_RUN() macro.
  */
 int bpf_prog_select_runtime(struct bpf_prog *fp)
 {
        fp->bpf_func = (void *) __bpf_prog_run;
 
-       /* Probe if internal BPF can be JITed */
        bpf_int_jit_compile(fp);
-       /* Lock whole bpf_prog as read-only */
        bpf_prog_lock_ro(fp);
 
-       return check_tail_call(fp);
+       /* The tail call compatibility check can only be done at
+        * this late stage as we need to determine, if we deal
+        * with JITed or non JITed program concatenations and not
+        * all eBPF JITs might immediately support all features.
+        */
+       return bpf_check_tail_call(fp);
 }
 EXPORT_SYMBOL_GPL(bpf_prog_select_runtime);
 
@@ -736,6 +731,21 @@ const struct bpf_func_proto bpf_get_prandom_u32_proto __weak;
 const struct bpf_func_proto bpf_get_smp_processor_id_proto __weak;
 const struct bpf_func_proto bpf_ktime_get_ns_proto __weak;
 
+/* Always built-in helper functions. */
+const struct bpf_func_proto bpf_tail_call_proto = {
+       .func           = NULL,
+       .gpl_only       = false,
+       .ret_type       = RET_VOID,
+       .arg1_type      = ARG_PTR_TO_CTX,
+       .arg2_type      = ARG_CONST_MAP_PTR,
+       .arg3_type      = ARG_ANYTHING,
+};
+
+/* For classic BPF JITs that don't implement bpf_int_jit_compile(). */
+void __weak bpf_int_jit_compile(struct bpf_prog *prog)
+{
+}
+
 /* To execute LD_ABS/LD_IND instructions __bpf_prog_run() may call
  * skb_copy_bits(), so provide a weak definition of it for NET-less config.
  */

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index b3aaabd..7ad5d88 100644 (file)
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -45,11 +45,11 @@ static u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
 }
 
 const struct bpf_func_proto bpf_map_lookup_elem_proto = {
-       .func = bpf_map_lookup_elem,
-       .gpl_only = false,
-       .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
-       .arg1_type = ARG_CONST_MAP_PTR,
-       .arg2_type = ARG_PTR_TO_MAP_KEY,
+       .func           = bpf_map_lookup_elem,
+       .gpl_only       = false,
+       .ret_type       = RET_PTR_TO_MAP_VALUE_OR_NULL,
+       .arg1_type      = ARG_CONST_MAP_PTR,
+       .arg2_type      = ARG_PTR_TO_MAP_KEY,
 };
 
 static u64 bpf_map_update_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
@@ -64,13 +64,13 @@ static u64 bpf_map_update_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
 }
 
 const struct bpf_func_proto bpf_map_update_elem_proto = {
-       .func = bpf_map_update_elem,
-       .gpl_only = false,
-       .ret_type = RET_INTEGER,
-       .arg1_type = ARG_CONST_MAP_PTR,
-       .arg2_type = ARG_PTR_TO_MAP_KEY,
-       .arg3_type = ARG_PTR_TO_MAP_VALUE,
-       .arg4_type = ARG_ANYTHING,
+       .func           = bpf_map_update_elem,
+       .gpl_only       = false,
+       .ret_type       = RET_INTEGER,
+       .arg1_type      = ARG_CONST_MAP_PTR,
+       .arg2_type      = ARG_PTR_TO_MAP_KEY,
+       .arg3_type      = ARG_PTR_TO_MAP_VALUE,
+       .arg4_type      = ARG_ANYTHING,
 };
 
 static u64 bpf_map_delete_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
@@ -84,11 +84,11 @@ static u64 bpf_map_delete_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
 }
 
 const struct bpf_func_proto bpf_map_delete_elem_proto = {
-       .func = bpf_map_delete_elem,
-       .gpl_only = false,
-       .ret_type = RET_INTEGER,
-       .arg1_type = ARG_CONST_MAP_PTR,
-       .arg2_type = ARG_PTR_TO_MAP_KEY,
+       .func           = bpf_map_delete_elem,
+       .gpl_only       = false,
+       .ret_type       = RET_INTEGER,
+       .arg1_type      = ARG_CONST_MAP_PTR,
+       .arg2_type      = ARG_PTR_TO_MAP_KEY,
 };
 
 static u64 bpf_get_prandom_u32(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)