This patch adds a "properties" member to "struct bpf_map".  The properties of
individual map-type is tagged in the "BPF_MAP_TYPE_FL" in bpf_types.h.
The original "BPF_MAP_TYPE" is defined to "BPF_MAP_TYPE_FL(..., 0)".

It will be less error prone when a map's properties is decided at the same
place as the new map type is added in bpf_types.h.  That will help to
avoid mistake like missing modification in other source files like
the map_in_map.c here or other source files in the future.

Cc: Andrey Ignatov <r...@fb.com>
Signed-off-by: Martin KaFai Lau <ka...@fb.com>
---
 include/linux/bpf.h       |  8 ++++++--
 include/linux/bpf_types.h | 19 +++++++++++++++----
 kernel/bpf/btf.c          |  4 ++--
 kernel/bpf/map_in_map.c   |  9 ++-------
 kernel/bpf/syscall.c      | 25 +++++++++++++++++++------
 kernel/bpf/verifier.c     |  4 ++--
 6 files changed, 46 insertions(+), 23 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index efe8836b5c48..f947d899aa46 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -97,6 +97,9 @@ struct bpf_map_memory {
        struct user_struct *user;
 };
 
+/* Cannot be used as an inner map */
+#define BPF_MAP_NO_INNER_MAP (1 << 0)
+
 struct bpf_map {
        /* The first two cachelines with read-mostly members of which some
         * are also accessed in fast-path (e.g. ops, max_entries).
@@ -120,6 +123,7 @@ struct bpf_map {
        struct bpf_map_memory memory;
        char name[BPF_OBJ_NAME_LEN];
        u32 btf_vmlinux_value_type_id;
+       u32 properties;
        bool bypass_spec_v1;
        bool frozen; /* write-once; write-protected by freeze_mutex */
        /* 22 bytes hole */
@@ -1037,12 +1041,12 @@ extern const struct file_operations bpf_iter_fops;
 #define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
        extern const struct bpf_prog_ops _name ## _prog_ops; \
        extern const struct bpf_verifier_ops _name ## _verifier_ops;
-#define BPF_MAP_TYPE(_id, _ops) \
+#define BPF_MAP_TYPE_FL(_id, _ops, properties) \
        extern const struct bpf_map_ops _ops;
 #define BPF_LINK_TYPE(_id, _name)
 #include <linux/bpf_types.h>
 #undef BPF_PROG_TYPE
-#undef BPF_MAP_TYPE
+#undef BPF_MAP_TYPE_FL
 #undef BPF_LINK_TYPE
 
 extern const struct bpf_prog_ops bpf_offload_prog_ops;
diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
index 29d22752fc87..3f32702c9bf4 100644
--- a/include/linux/bpf_types.h
+++ b/include/linux/bpf_types.h
@@ -76,16 +76,25 @@ BPF_PROG_TYPE(BPF_PROG_TYPE_LSM, lsm,
 #endif /* CONFIG_BPF_LSM */
 #endif
 
+#define BPF_MAP_TYPE(x, y) BPF_MAP_TYPE_FL(x, y, 0)
+
 BPF_MAP_TYPE(BPF_MAP_TYPE_ARRAY, array_map_ops)
 BPF_MAP_TYPE(BPF_MAP_TYPE_PERCPU_ARRAY, percpu_array_map_ops)
-BPF_MAP_TYPE(BPF_MAP_TYPE_PROG_ARRAY, prog_array_map_ops)
+/* prog_array->aux->{type,jited} is a runtime binding.
+ * Doing static check alone in the verifier is not enough,
+ * so BPF_MAP_NO_INNTER_MAP is needed.
+ */
+BPF_MAP_TYPE_FL(BPF_MAP_TYPE_PROG_ARRAY, prog_array_map_ops,
+               BPF_MAP_NO_INNER_MAP)
 BPF_MAP_TYPE(BPF_MAP_TYPE_PERF_EVENT_ARRAY, perf_event_array_map_ops)
 #ifdef CONFIG_CGROUPS
 BPF_MAP_TYPE(BPF_MAP_TYPE_CGROUP_ARRAY, cgroup_array_map_ops)
 #endif
 #ifdef CONFIG_CGROUP_BPF
-BPF_MAP_TYPE(BPF_MAP_TYPE_CGROUP_STORAGE, cgroup_storage_map_ops)
-BPF_MAP_TYPE(BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE, cgroup_storage_map_ops)
+BPF_MAP_TYPE_FL(BPF_MAP_TYPE_CGROUP_STORAGE, cgroup_storage_map_ops,
+               BPF_MAP_NO_INNER_MAP)
+BPF_MAP_TYPE_FL(BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE, cgroup_storage_map_ops,
+               BPF_MAP_NO_INNER_MAP)
 #endif
 BPF_MAP_TYPE(BPF_MAP_TYPE_HASH, htab_map_ops)
 BPF_MAP_TYPE(BPF_MAP_TYPE_PERCPU_HASH, htab_percpu_map_ops)
@@ -116,8 +125,10 @@ BPF_MAP_TYPE(BPF_MAP_TYPE_REUSEPORT_SOCKARRAY, 
reuseport_array_ops)
 BPF_MAP_TYPE(BPF_MAP_TYPE_QUEUE, queue_map_ops)
 BPF_MAP_TYPE(BPF_MAP_TYPE_STACK, stack_map_ops)
 #if defined(CONFIG_BPF_JIT)
-BPF_MAP_TYPE(BPF_MAP_TYPE_STRUCT_OPS, bpf_struct_ops_map_ops)
+BPF_MAP_TYPE_FL(BPF_MAP_TYPE_STRUCT_OPS, bpf_struct_ops_map_ops,
+               BPF_MAP_NO_INNER_MAP)
 #endif
+#undef BPF_MAP_TYPE
 
 BPF_LINK_TYPE(BPF_LINK_TYPE_RAW_TRACEPOINT, raw_tracepoint)
 BPF_LINK_TYPE(BPF_LINK_TYPE_TRACING, tracing)
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 58c9af1d4808..f527a120eef3 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3481,7 +3481,7 @@ extern char __weak __start_BTF[];
 extern char __weak __stop_BTF[];
 extern struct btf *btf_vmlinux;
 
-#define BPF_MAP_TYPE(_id, _ops)
+#define BPF_MAP_TYPE_FL(_id, _ops, properties)
 #define BPF_LINK_TYPE(_id, _name)
 static union {
        struct bpf_ctx_convert {
@@ -3508,7 +3508,7 @@ static u8 bpf_ctx_convert_map[] = {
 #undef BPF_PROG_TYPE
        0, /* avoid empty array */
 };
-#undef BPF_MAP_TYPE
+#undef BPF_MAP_TYPE_FL
 #undef BPF_LINK_TYPE
 
 static const struct btf_member *
diff --git a/kernel/bpf/map_in_map.c b/kernel/bpf/map_in_map.c
index 17738c93bec8..d965a1d328a9 100644
--- a/kernel/bpf/map_in_map.c
+++ b/kernel/bpf/map_in_map.c
@@ -17,13 +17,7 @@ struct bpf_map *bpf_map_meta_alloc(int inner_map_ufd)
        if (IS_ERR(inner_map))
                return inner_map;
 
-       /* prog_array->aux->{type,jited} is a runtime binding.
-        * Doing static check alone in the verifier is not enough.
-        */
-       if (inner_map->map_type == BPF_MAP_TYPE_PROG_ARRAY ||
-           inner_map->map_type == BPF_MAP_TYPE_CGROUP_STORAGE ||
-           inner_map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE ||
-           inner_map->map_type == BPF_MAP_TYPE_STRUCT_OPS) {
+       if (inner_map->properties & BPF_MAP_NO_INNER_MAP) {
                fdput(f);
                return ERR_PTR(-ENOTSUPP);
        }
@@ -56,6 +50,7 @@ struct bpf_map *bpf_map_meta_alloc(int inner_map_ufd)
        inner_map_meta->map_flags = inner_map->map_flags;
        inner_map_meta->max_entries = inner_map->max_entries;
        inner_map_meta->spin_lock_off = inner_map->spin_lock_off;
+       inner_map_meta->properties = inner_map->properties;
 
        /* Misc members not needed in bpf_map_meta_equal() check. */
        inner_map_meta->ops = inner_map->ops;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 431241c74614..02ec14e3e19a 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -49,12 +49,23 @@ int sysctl_unprivileged_bpf_disabled __read_mostly;
 
 static const struct bpf_map_ops * const bpf_map_types[] = {
 #define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type)
-#define BPF_MAP_TYPE(_id, _ops) \
+#define BPF_MAP_TYPE_FL(_id, _ops, properties) \
        [_id] = &_ops,
 #define BPF_LINK_TYPE(_id, _name)
 #include <linux/bpf_types.h>
 #undef BPF_PROG_TYPE
-#undef BPF_MAP_TYPE
+#undef BPF_MAP_TYPE_FL
+#undef BPF_LINK_TYPE
+};
+
+static const u32 bpf_map_properties[] = {
+#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type)
+#define BPF_MAP_TYPE_FL(_id, _ops, properties) \
+       [_id] = properties,
+#define BPF_LINK_TYPE(_id, _name)
+#include <linux/bpf_types.h>
+#undef BPF_PROG_TYPE
+#undef BPF_MAP_TYPE_FL
 #undef BPF_LINK_TYPE
 };
 
@@ -131,6 +142,8 @@ static struct bpf_map *find_and_alloc_map(union bpf_attr 
*attr)
                return map;
        map->ops = ops;
        map->map_type = type;
+       map->properties = bpf_map_properties[type];
+
        return map;
 }
 
@@ -1551,11 +1564,11 @@ static int map_freeze(const union bpf_attr *attr)
 static const struct bpf_prog_ops * const bpf_prog_types[] = {
 #define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
        [_id] = & _name ## _prog_ops,
-#define BPF_MAP_TYPE(_id, _ops)
+#define BPF_MAP_TYPE_FL(_id, _ops, properties)
 #define BPF_LINK_TYPE(_id, _name)
 #include <linux/bpf_types.h>
 #undef BPF_PROG_TYPE
-#undef BPF_MAP_TYPE
+#undef BPF_MAP_TYPE_FL
 #undef BPF_LINK_TYPE
 };
 
@@ -2333,14 +2346,14 @@ static int bpf_link_release(struct inode *inode, struct 
file *filp)
 
 #ifdef CONFIG_PROC_FS
 #define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type)
-#define BPF_MAP_TYPE(_id, _ops)
+#define BPF_MAP_TYPE_FL(_id, _ops, properties)
 #define BPF_LINK_TYPE(_id, _name) [_id] = #_name,
 static const char *bpf_link_type_strs[] = {
        [BPF_LINK_TYPE_UNSPEC] = "<invalid>",
 #include <linux/bpf_types.h>
 };
 #undef BPF_PROG_TYPE
-#undef BPF_MAP_TYPE
+#undef BPF_MAP_TYPE_FL
 #undef BPF_LINK_TYPE
 
 static void bpf_link_show_fdinfo(struct seq_file *m, struct file *filp)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 2ed8351f47a4..1743e070d08f 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -27,11 +27,11 @@
 static const struct bpf_verifier_ops * const bpf_verifier_ops[] = {
 #define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
        [_id] = & _name ## _verifier_ops,
-#define BPF_MAP_TYPE(_id, _ops)
+#define BPF_MAP_TYPE_FL(_id, _ops, properties)
 #define BPF_LINK_TYPE(_id, _name)
 #include <linux/bpf_types.h>
 #undef BPF_PROG_TYPE
-#undef BPF_MAP_TYPE
+#undef BPF_MAP_TYPE_FL
 #undef BPF_LINK_TYPE
 };
 
-- 
2.24.1

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