[PATCH bpf-next 1/3] bpf: pass struct btf pointer to the map_check_btf() callback

[PATCH bpf-next 1/3] bpf: pass struct btf pointer to the map_check_btf() callback

[Roman Gushchin]

If key_type or value_type are of non-trivial data types
(e.g. structure or typedef), it's not possible to check them without
the additional information, which can't be obtained without a pointer
to the btf structure.

So, let's pass btf pointer to the map_check_btf() callbacks.

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
---
 include/linux/bpf.h   | 3 +++
 kernel/bpf/arraymap.c | 1 +
 kernel/bpf/lpm_trie.c | 1 +
 kernel/bpf/syscall.c  | 3 ++-
 4 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index e82b7039fc66..128d93540b23 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -23,6 +23,7 @@ struct bpf_prog;
 struct bpf_map;
 struct sock;
 struct seq_file;
+struct btf;
 struct btf_type;
 
 /* map is generic key/value storage optionally accesible by eBPF programs */
@@ -52,6 +53,7 @@ struct bpf_map_ops {
 	void (*map_seq_show_elem)(struct bpf_map *map, void *key,
 				  struct seq_file *m);
 	int (*map_check_btf)(const struct bpf_map *map,
+			     const struct btf *btf,
 			     const struct btf_type *key_type,
 			     const struct btf_type *value_type);
 };
@@ -126,6 +128,7 @@ static inline bool bpf_map_support_seq_show(const struct bpf_map *map)
 }
 
 int map_check_no_btf(const struct bpf_map *map,
+		     const struct btf *btf,
 		     const struct btf_type *key_type,
 		     const struct btf_type *value_type);
 
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 24583da9ffd1..25632a75d630 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -382,6 +382,7 @@ static void percpu_array_map_seq_show_elem(struct bpf_map *map, void *key,
 }
 
 static int array_map_check_btf(const struct bpf_map *map,
+			       const struct btf *btf,
 			       const struct btf_type *key_type,
 			       const struct btf_type *value_type)
 {
diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c
index bfd4882e1106..abf1002080df 100644
--- a/kernel/bpf/lpm_trie.c
+++ b/kernel/bpf/lpm_trie.c
@@ -728,6 +728,7 @@ static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key)
 }
 
 static int trie_check_btf(const struct bpf_map *map,
+			  const struct btf *btf,
 			  const struct btf_type *key_type,
 			  const struct btf_type *value_type)
 {
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index aa05aa38f4a8..7c2e8ab03a34 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -456,6 +456,7 @@ static int bpf_obj_name_cpy(char *dst, const char *src)
 }
 
 int map_check_no_btf(const struct bpf_map *map,
+		     const struct btf *btf,
 		     const struct btf_type *key_type,
 		     const struct btf_type *value_type)
 {
@@ -478,7 +479,7 @@ static int map_check_btf(const struct bpf_map *map, const struct btf *btf,
 		return -EINVAL;
 
 	if (map->ops->map_check_btf)
-		ret = map->ops->map_check_btf(map, key_type, value_type);
+		ret = map->ops->map_check_btf(map, btf, key_type, value_type);
 
 	return ret;
 }
-- 
2.19.2

[PATCH bpf-next 2/3] bpf: add bpffs pretty print for cgroup local storage maps

[Roman Gushchin]

Implement bpffs pretty printing for cgroup local storage maps
(both shared and per-cpu).
Output example (captured for tools/testing/selftests/bpf/netcnt_prog.c):

Shared:
  $ cat /sys/fs/bpf/map_2
  # WARNING!! The output is for debug purpose only
  # WARNING!! The output format will change
  {4294968594,1}: {9999,1039896}

Per-cpu:
  $ cat /sys/fs/bpf/map_1
  # WARNING!! The output is for debug purpose only
  # WARNING!! The output format will change
  {4294968594,1}: {
  	cpu0: {0,0,0,0,0}
  	cpu1: {0,0,0,0,0}
  	cpu2: {1,104,0,0,0}
  	cpu3: {0,0,0,0,0}
  }

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
---
 include/linux/btf.h        | 10 +++++
 kernel/bpf/local_storage.c | 90 +++++++++++++++++++++++++++++++++++++-
 2 files changed, 99 insertions(+), 1 deletion(-)

diff --git a/include/linux/btf.h b/include/linux/btf.h
index 8c2199b5d250..ac67bc4cbfd9 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -5,6 +5,7 @@
 #define _LINUX_BTF_H 1
 
 #include <linux/types.h>
+#include <uapi/linux/btf.h>
 
 struct btf;
 struct btf_type;
@@ -63,4 +64,13 @@ static inline const char *btf_name_by_offset(const struct btf *btf,
 }
 #endif
 
+static inline const struct btf_type *btf_orig_type(const struct btf *btf,
+						   const struct btf_type *t)
+{
+	while (t && BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF)
+		t = btf_type_by_id(btf, t->type);
+
+	return t;
+}
+
 #endif
diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
index b65017dead44..7b51fe1aba3c 100644
--- a/kernel/bpf/local_storage.c
+++ b/kernel/bpf/local_storage.c
@@ -1,11 +1,13 @@
 //SPDX-License-Identifier: GPL-2.0
 #include <linux/bpf-cgroup.h>
 #include <linux/bpf.h>
+#include <linux/btf.h>
 #include <linux/bug.h>
 #include <linux/filter.h>
 #include <linux/mm.h>
 #include <linux/rbtree.h>
 #include <linux/slab.h>
+#include <uapi/linux/btf.h>
 
 DEFINE_PER_CPU(struct bpf_cgroup_storage*, bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
 
@@ -308,6 +310,91 @@ static int cgroup_storage_delete_elem(struct bpf_map *map, void *key)
 	return -EINVAL;
 }
 
+static int cgroup_storage_check_btf(const struct bpf_map *map,
+				    const struct btf *btf,
+				    const struct btf_type *key_type,
+				    const struct btf_type *value_type)
+{
+	const struct btf_type *st, *t;
+	struct btf_member *m;
+
+	/* Key is expected to be of struct bpf_cgroup_storage_key type,
+	 * which is:
+	 * struct bpf_cgroup_storage_key {
+	 *	__u64	cgroup_inode_id;
+	 *	__u32	attach_type;
+	 * };
+	 */
+
+	/*
+	 * Key_type must be a structure (or a typedef of a structure) with
+	 * two members.
+	 */
+	st = btf_orig_type(btf, key_type);
+	if (BTF_INFO_KIND(st->info) != BTF_KIND_STRUCT ||
+	    BTF_INFO_VLEN(st->info) != 2)
+		return -EINVAL;
+
+	/*
+	 * The first field must be a 64 bit integer at 0 offset.
+	 */
+	m = (struct btf_member *)(st + 1);
+	t = btf_orig_type(btf, btf_type_by_id(btf, m->type));
+	if (!t || BTF_INFO_KIND(t->info) != BTF_KIND_INT || m->offset ||
+	    t->size !=
+	    FIELD_SIZEOF(struct bpf_cgroup_storage_key, cgroup_inode_id))
+		return -EINVAL;
+
+	/*
+	 * The second field must be a 32 bit integer at 0 offset.
+	 */
+	m = m + 1;
+	t = btf_orig_type(btf, btf_type_by_id(btf, m->type));
+	if (!t || BTF_INFO_KIND(t->info) != BTF_KIND_INT ||
+	    m->offset != offsetof(struct bpf_cgroup_storage_key, attach_type) *
+	    BITS_PER_BYTE || t->size !=
+	    FIELD_SIZEOF(struct bpf_cgroup_storage_key, attach_type))
+		return -EINVAL;
+
+	return 0;
+}
+
+static void cgroup_storage_seq_show_elem(struct bpf_map *map, void *_key,
+					 struct seq_file *m)
+{
+	enum bpf_cgroup_storage_type stype = cgroup_storage_type(map);
+	struct bpf_cgroup_storage_key *key = _key;
+	struct bpf_cgroup_storage *storage;
+	int cpu;
+
+	rcu_read_lock();
+	storage = cgroup_storage_lookup(map_to_storage(map), key, false);
+	if (!storage) {
+		rcu_read_unlock();
+		return;
+	}
+
+	btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
+	stype = cgroup_storage_type(map);
+	if (stype == BPF_CGROUP_STORAGE_SHARED) {
+		seq_puts(m, ": ");
+		btf_type_seq_show(map->btf, map->btf_value_type_id,
+				  &READ_ONCE(storage->buf)->data[0], m);
+		seq_puts(m, "\n");
+	} else {
+		seq_puts(m, ": {\n");
+		for_each_possible_cpu(cpu) {
+			seq_printf(m, "\tcpu%d: ", cpu);
+			btf_type_seq_show(map->btf, map->btf_value_type_id,
+					  per_cpu_ptr(storage->percpu_buf, cpu),
+					  m);
+			seq_puts(m, "\n");
+		}
+		seq_puts(m, "}\n");
+	}
+	rcu_read_unlock();
+}
+
 const struct bpf_map_ops cgroup_storage_map_ops = {
 	.map_alloc = cgroup_storage_map_alloc,
 	.map_free = cgroup_storage_map_free,
@@ -315,7 +402,8 @@ const struct bpf_map_ops cgroup_storage_map_ops = {
 	.map_lookup_elem = cgroup_storage_lookup_elem,
 	.map_update_elem = cgroup_storage_update_elem,
 	.map_delete_elem = cgroup_storage_delete_elem,
-	.map_check_btf = map_check_no_btf,
+	.map_check_btf = cgroup_storage_check_btf,
+	.map_seq_show_elem = cgroup_storage_seq_show_elem,
 };
 
 int bpf_cgroup_storage_assign(struct bpf_prog *prog, struct bpf_map *_map)
-- 
2.19.2

[PATCH bpf-next 3/3] selftests/bpf: add btf annotations for cgroup_local_storage maps

[Roman Gushchin]

Add btf annotations to cgroup local storage maps (per-cpu and shared)
in the network packet counting example.

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
---
 tools/testing/selftests/bpf/netcnt_prog.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/testing/selftests/bpf/netcnt_prog.c b/tools/testing/selftests/bpf/netcnt_prog.c
index 1198abca1360..9f741e69cebe 100644
--- a/tools/testing/selftests/bpf/netcnt_prog.c
+++ b/tools/testing/selftests/bpf/netcnt_prog.c
@@ -16,12 +16,18 @@ struct bpf_map_def SEC("maps") percpu_netcnt = {
 	.value_size = sizeof(struct percpu_net_cnt),
 };
 
+BPF_ANNOTATE_KV_PAIR(percpu_netcnt, struct bpf_cgroup_storage_key,
+		     struct percpu_net_cnt);
+
 struct bpf_map_def SEC("maps") netcnt = {
 	.type = BPF_MAP_TYPE_CGROUP_STORAGE,
 	.key_size = sizeof(struct bpf_cgroup_storage_key),
 	.value_size = sizeof(struct net_cnt),
 };
 
+BPF_ANNOTATE_KV_PAIR(netcnt, struct bpf_cgroup_storage_key,
+		     struct net_cnt);
+
 SEC("cgroup/skb")
 int bpf_nextcnt(struct __sk_buff *skb)
 {
-- 
2.19.2

Re: [PATCH bpf-next 2/3] bpf: add bpffs pretty print for cgroup local storage maps

[Yonghong Song]

On 12/7/18 4:53 PM, Roman Gushchin wrote:
> Implement bpffs pretty printing for cgroup local storage maps
> (both shared and per-cpu).
> Output example (captured for tools/testing/selftests/bpf/netcnt_prog.c):
> 
> Shared:
>    $ cat /sys/fs/bpf/map_2
>    # WARNING!! The output is for debug purpose only
>    # WARNING!! The output format will change
>    {4294968594,1}: {9999,1039896}
> 
> Per-cpu:
>    $ cat /sys/fs/bpf/map_1
>    # WARNING!! The output is for debug purpose only
>    # WARNING!! The output format will change
>    {4294968594,1}: {
>    	cpu0: {0,0,0,0,0}
>    	cpu1: {0,0,0,0,0}
>    	cpu2: {1,104,0,0,0}
>    	cpu3: {0,0,0,0,0}
>    }
> 
> Signed-off-by: Roman Gushchin <guro@fb.com>
> Cc: Alexei Starovoitov <ast@kernel.org>
> Cc: Daniel Borkmann <daniel@iogearbox.net>
> ---
>   include/linux/btf.h        | 10 +++++
>   kernel/bpf/local_storage.c | 90 +++++++++++++++++++++++++++++++++++++-
>   2 files changed, 99 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/btf.h b/include/linux/btf.h
> index 8c2199b5d250..ac67bc4cbfd9 100644
> --- a/include/linux/btf.h
> +++ b/include/linux/btf.h
> @@ -5,6 +5,7 @@
>   #define _LINUX_BTF_H 1
>   
>   #include <linux/types.h>
> +#include <uapi/linux/btf.h>
>   
>   struct btf;
>   struct btf_type;
> @@ -63,4 +64,13 @@ static inline const char *btf_name_by_offset(const struct btf *btf,
>   }
>   #endif
>   
> +static inline const struct btf_type *btf_orig_type(const struct btf *btf,
> +						   const struct btf_type *t)
> +{
> +	while (t && BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF)
> +		t = btf_type_by_id(btf, t->type);
technically, type modifier "const" and "volatile" can apply to member 
type as well. But these modifiers really don't make sense here.
Could you add a comment here to mention that they will be treated
as an error since such a programming is not really recommended?

> +
> +	return t;
> +}
> +
>   #endif
> diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
> index b65017dead44..7b51fe1aba3c 100644
> --- a/kernel/bpf/local_storage.c
> +++ b/kernel/bpf/local_storage.c
> @@ -1,11 +1,13 @@
>   //SPDX-License-Identifier: GPL-2.0
>   #include <linux/bpf-cgroup.h>
>   #include <linux/bpf.h>
> +#include <linux/btf.h>
>   #include <linux/bug.h>
>   #include <linux/filter.h>
>   #include <linux/mm.h>
>   #include <linux/rbtree.h>
>   #include <linux/slab.h>
> +#include <uapi/linux/btf.h>
>   
>   DEFINE_PER_CPU(struct bpf_cgroup_storage*, bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
>   
> @@ -308,6 +310,91 @@ static int cgroup_storage_delete_elem(struct bpf_map *map, void *key)
>   	return -EINVAL;
>   }
>   
> +static int cgroup_storage_check_btf(const struct bpf_map *map,
> +				    const struct btf *btf,
> +				    const struct btf_type *key_type,
> +				    const struct btf_type *value_type)
> +{
> +	const struct btf_type *st, *t;
> +	struct btf_member *m;
> +
> +	/* Key is expected to be of struct bpf_cgroup_storage_key type,
> +	 * which is:
> +	 * struct bpf_cgroup_storage_key {
> +	 *	__u64	cgroup_inode_id;
> +	 *	__u32	attach_type;
> +	 * };
> +	 */
> +
> +	/*
> +	 * Key_type must be a structure (or a typedef of a structure) with
> +	 * two members.
> +	 */
> +	st = btf_orig_type(btf, key_type);
> +	if (BTF_INFO_KIND(st->info) != BTF_KIND_STRUCT ||
> +	    BTF_INFO_VLEN(st->info) != 2)
> +		return -EINVAL;
> +
> +	/*
> +	 * The first field must be a 64 bit integer at 0 offset.
> +	 */
> +	m = (struct btf_member *)(st + 1);
> +	t = btf_orig_type(btf, btf_type_by_id(btf, m->type));
> +	if (!t || BTF_INFO_KIND(t->info) != BTF_KIND_INT || m->offset ||
> +	    t->size !=
> +	    FIELD_SIZEOF(struct bpf_cgroup_storage_key, cgroup_inode_id))
> +		return -EINVAL;

We should not use t->size here. The "t->size" is the type size, and the
real number of bits held by the member is BTF_INT_BITS(...) with the 
argument of the u32 int value after "t".

> +
> +	/*
> +	 * The second field must be a 32 bit integer at 0 offset.
> +	 */
> +	m = m + 1;
> +	t = btf_orig_type(btf, btf_type_by_id(btf, m->type));
> +	if (!t || BTF_INFO_KIND(t->info) != BTF_KIND_INT ||
> +	    m->offset != offsetof(struct bpf_cgroup_storage_key, attach_type) *
> +	    BITS_PER_BYTE || t->size !=
> +	    FIELD_SIZEOF(struct bpf_cgroup_storage_key, attach_type))
> +		return -EINVAL;

The same is here. t->size should not be used.
BTF_INT_BITS(...) should be used.

> +
> +	return 0;
> +}
> +
> +static void cgroup_storage_seq_show_elem(struct bpf_map *map, void *_key,
> +					 struct seq_file *m)
> +{
> +	enum bpf_cgroup_storage_type stype = cgroup_storage_type(map);
> +	struct bpf_cgroup_storage_key *key = _key;
> +	struct bpf_cgroup_storage *storage;
> +	int cpu;
> +
> +	rcu_read_lock();
> +	storage = cgroup_storage_lookup(map_to_storage(map), key, false);
> +	if (!storage) {
> +		rcu_read_unlock();
> +		return;
> +	}
> +
> +	btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
> +	stype = cgroup_storage_type(map);
> +	if (stype == BPF_CGROUP_STORAGE_SHARED) {
> +		seq_puts(m, ": ");
> +		btf_type_seq_show(map->btf, map->btf_value_type_id,
> +				  &READ_ONCE(storage->buf)->data[0], m);
> +		seq_puts(m, "\n");
> +	} else {
> +		seq_puts(m, ": {\n");
> +		for_each_possible_cpu(cpu) {
> +			seq_printf(m, "\tcpu%d: ", cpu);
> +			btf_type_seq_show(map->btf, map->btf_value_type_id,
> +					  per_cpu_ptr(storage->percpu_buf, cpu),
> +					  m);
> +			seq_puts(m, "\n");
> +		}
> +		seq_puts(m, "}\n");
> +	}
> +	rcu_read_unlock();
> +}
> +
>   const struct bpf_map_ops cgroup_storage_map_ops = {
>   	.map_alloc = cgroup_storage_map_alloc,
>   	.map_free = cgroup_storage_map_free,
> @@ -315,7 +402,8 @@ const struct bpf_map_ops cgroup_storage_map_ops = {
>   	.map_lookup_elem = cgroup_storage_lookup_elem,
>   	.map_update_elem = cgroup_storage_update_elem,
>   	.map_delete_elem = cgroup_storage_delete_elem,
> -	.map_check_btf = map_check_no_btf,
> +	.map_check_btf = cgroup_storage_check_btf,
> +	.map_seq_show_elem = cgroup_storage_seq_show_elem,
>   };
>   
>   int bpf_cgroup_storage_assign(struct bpf_prog *prog, struct bpf_map *_map)
> 

Re: [PATCH bpf-next 2/3] bpf: add bpffs pretty print for cgroup local storage maps

[Martin Lau]

On Fri, Dec 07, 2018 at 04:53:14PM -0800, Roman Gushchin wrote:
> Implement bpffs pretty printing for cgroup local storage maps
> (both shared and per-cpu).
> Output example (captured for tools/testing/selftests/bpf/netcnt_prog.c):
> 
> Shared:
>   $ cat /sys/fs/bpf/map_2
>   # WARNING!! The output is for debug purpose only
>   # WARNING!! The output format will change
>   {4294968594,1}: {9999,1039896}
> 
> Per-cpu:
>   $ cat /sys/fs/bpf/map_1
>   # WARNING!! The output is for debug purpose only
>   # WARNING!! The output format will change
>   {4294968594,1}: {
>   	cpu0: {0,0,0,0,0}
>   	cpu1: {0,0,0,0,0}
>   	cpu2: {1,104,0,0,0}
>   	cpu3: {0,0,0,0,0}
>   }
> 
> Signed-off-by: Roman Gushchin <guro@fb.com>
> Cc: Alexei Starovoitov <ast@kernel.org>
> Cc: Daniel Borkmann <daniel@iogearbox.net>
> ---
>  include/linux/btf.h        | 10 +++++
>  kernel/bpf/local_storage.c | 90 +++++++++++++++++++++++++++++++++++++-
>  2 files changed, 99 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/btf.h b/include/linux/btf.h
> index 8c2199b5d250..ac67bc4cbfd9 100644
> --- a/include/linux/btf.h
> +++ b/include/linux/btf.h
> @@ -5,6 +5,7 @@
>  #define _LINUX_BTF_H 1
>  
>  #include <linux/types.h>
> +#include <uapi/linux/btf.h>
>  
>  struct btf;
>  struct btf_type;
> @@ -63,4 +64,13 @@ static inline const char *btf_name_by_offset(const struct btf *btf,
>  }
>  #endif
>  
> +static inline const struct btf_type *btf_orig_type(const struct btf *btf,
> +						   const struct btf_type *t)
> +{
> +	while (t && BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF)
> +		t = btf_type_by_id(btf, t->type);
Only typedef is allowed?  Not even const?
If that is not the case, can btf_type_id_size() be reused?
The "type following" has already been done once and then remembered
in the verification time.

If cgroup_storage_check_btf() can only allow typedef, please
move "btf_orig_type()" to the local_storage.c.

> +
> +	return t;
> +}
> +
>  #endif
> diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
> index b65017dead44..7b51fe1aba3c 100644
> --- a/kernel/bpf/local_storage.c
> +++ b/kernel/bpf/local_storage.c
> @@ -1,11 +1,13 @@
>  //SPDX-License-Identifier: GPL-2.0
>  #include <linux/bpf-cgroup.h>
>  #include <linux/bpf.h>
> +#include <linux/btf.h>
>  #include <linux/bug.h>
>  #include <linux/filter.h>
>  #include <linux/mm.h>
>  #include <linux/rbtree.h>
>  #include <linux/slab.h>
> +#include <uapi/linux/btf.h>
>  
>  DEFINE_PER_CPU(struct bpf_cgroup_storage*, bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
>  
> @@ -308,6 +310,91 @@ static int cgroup_storage_delete_elem(struct bpf_map *map, void *key)
>  	return -EINVAL;
>  }
>  
> +static int cgroup_storage_check_btf(const struct bpf_map *map,
> +				    const struct btf *btf,
> +				    const struct btf_type *key_type,
Actually, in "map_check_btf()" (just before cgroup_storage_check_btf()
is called), btf_type_id_size() has already been called
to get the true size and the resolved type (i.e. BTF_INFO_KIND_STRUCT here)
in order to reject "key_size != map->key_size".  Hence, the key_type
passed to cgroup_storage_check_btf() here will not be KIND_TYPEDEF or
KIND_CONST.

> +				    const struct btf_type *value_type)
> +{
> +	const struct btf_type *st, *t;
> +	struct btf_member *m;
> +
> +	/* Key is expected to be of struct bpf_cgroup_storage_key type,
> +	 * which is:
> +	 * struct bpf_cgroup_storage_key {
> +	 *	__u64	cgroup_inode_id;
> +	 *	__u32	attach_type;
> +	 * };
> +	 */
> +
> +	/*
> +	 * Key_type must be a structure (or a typedef of a structure) with
> +	 * two members.
> +	 */
> +	st = btf_orig_type(btf, key_type);
> +	if (BTF_INFO_KIND(st->info) != BTF_KIND_STRUCT ||
> +	    BTF_INFO_VLEN(st->info) != 2)
> +		return -EINVAL;
> +
> +	/*
> +	 * The first field must be a 64 bit integer at 0 offset.
> +	 */
> +	m = (struct btf_member *)(st + 1);
> +	t = btf_orig_type(btf, btf_type_by_id(btf, m->type));
> +	if (!t || BTF_INFO_KIND(t->info) != BTF_KIND_INT || m->offset ||
> +	    t->size !=
> +	    FIELD_SIZEOF(struct bpf_cgroup_storage_key, cgroup_inode_id))
Instead of t->size,
BTF_INT_BITS() and BTF_INT_OFFSET() need to be checked (please refer to the
key_type check in array_map_check_btf()).

I think exposing "btf_type_int_is_regular()" from btf.c will be easier here.
Actually, add "btf_type_is_reg_int(t, expected_size)" to btf.h and btf.c,
like (uncompiled and untested code):

/*
 * Not a bit field and it must be the expected size.
 */
bool btf_type_is_reg_int(const struct btf_type *t, u32 expected_size)
{
 	u8 nr_bits, nr_bytes;
        u32 int_data;

	if (!btf_type_is_int(t))
		return false;

	int_data = btf_type_int(t);
	nr_bits = BTF_INT_BITS(int_data);
	nr_bytes = BITS_ROUNDUP_BYTES(nr_bits);
	if (BITS_PER_BYTE_MASKED(nr_bits) ||
	    BTF_INT_OFFSET(int_data) ||
	    nr_bytes != expected_size)
                return false;

	return true;
}


> +		return -EINVAL;
> +
> +	/*
> +	 * The second field must be a 32 bit integer at 0 offset.
> +	 */
> +	m = m + 1;
> +	t = btf_orig_type(btf, btf_type_by_id(btf, m->type));
> +	if (!t || BTF_INFO_KIND(t->info) != BTF_KIND_INT ||
> +	    m->offset != offsetof(struct bpf_cgroup_storage_key, attach_type) *
> +	    BITS_PER_BYTE || t->size !=
> +	    FIELD_SIZEOF(struct bpf_cgroup_storage_key, attach_type))
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static void cgroup_storage_seq_show_elem(struct bpf_map *map, void *_key,
> +					 struct seq_file *m)
> +{
> +	enum bpf_cgroup_storage_type stype = cgroup_storage_type(map);
> +	struct bpf_cgroup_storage_key *key = _key;
> +	struct bpf_cgroup_storage *storage;
> +	int cpu;
> +
> +	rcu_read_lock();
> +	storage = cgroup_storage_lookup(map_to_storage(map), key, false);
> +	if (!storage) {
> +		rcu_read_unlock();
> +		return;
> +	}
> +
> +	btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
> +	stype = cgroup_storage_type(map);
> +	if (stype == BPF_CGROUP_STORAGE_SHARED) {
> +		seq_puts(m, ": ");
> +		btf_type_seq_show(map->btf, map->btf_value_type_id,
> +				  &READ_ONCE(storage->buf)->data[0], m);
> +		seq_puts(m, "\n");
> +	} else {
> +		seq_puts(m, ": {\n");
> +		for_each_possible_cpu(cpu) {
> +			seq_printf(m, "\tcpu%d: ", cpu);
> +			btf_type_seq_show(map->btf, map->btf_value_type_id,
> +					  per_cpu_ptr(storage->percpu_buf, cpu),
> +					  m);
> +			seq_puts(m, "\n");
> +		}
> +		seq_puts(m, "}\n");
> +	}
> +	rcu_read_unlock();
> +}
> +
>  const struct bpf_map_ops cgroup_storage_map_ops = {
>  	.map_alloc = cgroup_storage_map_alloc,
>  	.map_free = cgroup_storage_map_free,
> @@ -315,7 +402,8 @@ const struct bpf_map_ops cgroup_storage_map_ops = {
>  	.map_lookup_elem = cgroup_storage_lookup_elem,
>  	.map_update_elem = cgroup_storage_update_elem,
>  	.map_delete_elem = cgroup_storage_delete_elem,
> -	.map_check_btf = map_check_no_btf,
> +	.map_check_btf = cgroup_storage_check_btf,
> +	.map_seq_show_elem = cgroup_storage_seq_show_elem,
>  };
>  
>  int bpf_cgroup_storage_assign(struct bpf_prog *prog, struct bpf_map *_map)
> -- 
> 2.19.2
> 

Re: [PATCH bpf-next 1/3] bpf: pass struct btf pointer to the map_check_btf() callback

[Martin Lau]

On Fri, Dec 07, 2018 at 04:53:13PM -0800, Roman Gushchin wrote:
> If key_type or value_type are of non-trivial data types
> (e.g. structure or typedef), it's not possible to check them without
> the additional information, which can't be obtained without a pointer
> to the btf structure.
> 
> So, let's pass btf pointer to the map_check_btf() callbacks.
Acked-by: Martin KaFai Lau <kafai@fb.com>

Re: [PATCH bpf-next 2/3] bpf: add bpffs pretty print for cgroup local storage maps

[Roman Gushchin]

On Sat, Dec 08, 2018 at 05:56:30PM -0800, Martin Lau wrote:
> On Fri, Dec 07, 2018 at 04:53:14PM -0800, Roman Gushchin wrote:
> > Implement bpffs pretty printing for cgroup local storage maps
> > (both shared and per-cpu).
> > Output example (captured for tools/testing/selftests/bpf/netcnt_prog.c):
> > 
> > Shared:
> >   $ cat /sys/fs/bpf/map_2
> >   # WARNING!! The output is for debug purpose only
> >   # WARNING!! The output format will change
> >   {4294968594,1}: {9999,1039896}
> > 
> > Per-cpu:
> >   $ cat /sys/fs/bpf/map_1
> >   # WARNING!! The output is for debug purpose only
> >   # WARNING!! The output format will change
> >   {4294968594,1}: {
> >   	cpu0: {0,0,0,0,0}
> >   	cpu1: {0,0,0,0,0}
> >   	cpu2: {1,104,0,0,0}
> >   	cpu3: {0,0,0,0,0}
> >   }
> > 
> > Signed-off-by: Roman Gushchin <guro@fb.com>
> > Cc: Alexei Starovoitov <ast@kernel.org>
> > Cc: Daniel Borkmann <daniel@iogearbox.net>
> > ---
> >  include/linux/btf.h        | 10 +++++
> >  kernel/bpf/local_storage.c | 90 +++++++++++++++++++++++++++++++++++++-
> >  2 files changed, 99 insertions(+), 1 deletion(-)
> > 
> > diff --git a/include/linux/btf.h b/include/linux/btf.h
> > index 8c2199b5d250..ac67bc4cbfd9 100644
> > --- a/include/linux/btf.h
> > +++ b/include/linux/btf.h
> > @@ -5,6 +5,7 @@
> >  #define _LINUX_BTF_H 1
> >  
> >  #include <linux/types.h>
> > +#include <uapi/linux/btf.h>
> >  
> >  struct btf;
> >  struct btf_type;
> > @@ -63,4 +64,13 @@ static inline const char *btf_name_by_offset(const struct btf *btf,
> >  }
> >  #endif
> >  
> > +static inline const struct btf_type *btf_orig_type(const struct btf *btf,
> > +						   const struct btf_type *t)
> > +{
> > +	while (t && BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF)
> > +		t = btf_type_by_id(btf, t->type);
> Only typedef is allowed?  Not even const?
> If that is not the case, can btf_type_id_size() be reused?
> The "type following" has already been done once and then remembered
> in the verification time.
> 
> If cgroup_storage_check_btf() can only allow typedef, please
> move "btf_orig_type()" to the local_storage.c.
> 
> > +
> > +	return t;
> > +}
> > +
> >  #endif
> > diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
> > index b65017dead44..7b51fe1aba3c 100644
> > --- a/kernel/bpf/local_storage.c
> > +++ b/kernel/bpf/local_storage.c
> > @@ -1,11 +1,13 @@
> >  //SPDX-License-Identifier: GPL-2.0
> >  #include <linux/bpf-cgroup.h>
> >  #include <linux/bpf.h>
> > +#include <linux/btf.h>
> >  #include <linux/bug.h>
> >  #include <linux/filter.h>
> >  #include <linux/mm.h>
> >  #include <linux/rbtree.h>
> >  #include <linux/slab.h>
> > +#include <uapi/linux/btf.h>
> >  
> >  DEFINE_PER_CPU(struct bpf_cgroup_storage*, bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
> >  
> > @@ -308,6 +310,91 @@ static int cgroup_storage_delete_elem(struct bpf_map *map, void *key)
> >  	return -EINVAL;
> >  }
> >  
> > +static int cgroup_storage_check_btf(const struct bpf_map *map,
> > +				    const struct btf *btf,
> > +				    const struct btf_type *key_type,
> Actually, in "map_check_btf()" (just before cgroup_storage_check_btf()
> is called), btf_type_id_size() has already been called
> to get the true size and the resolved type (i.e. BTF_INFO_KIND_STRUCT here)
> in order to reject "key_size != map->key_size".  Hence, the key_type
> passed to cgroup_storage_check_btf() here will not be KIND_TYPEDEF or
> KIND_CONST.

So, the type here is a structure, and its fields are typedefs of ints.
Looks like reusing btf_type_id_size() is the best approach.

> 
> > +				    const struct btf_type *value_type)
> > +{
> > +	const struct btf_type *st, *t;
> > +	struct btf_member *m;
> > +
> > +	/* Key is expected to be of struct bpf_cgroup_storage_key type,
> > +	 * which is:
> > +	 * struct bpf_cgroup_storage_key {
> > +	 *	__u64	cgroup_inode_id;
> > +	 *	__u32	attach_type;
> > +	 * };
> > +	 */
> > +
> > +	/*
> > +	 * Key_type must be a structure (or a typedef of a structure) with
> > +	 * two members.
> > +	 */
> > +	st = btf_orig_type(btf, key_type);
> > +	if (BTF_INFO_KIND(st->info) != BTF_KIND_STRUCT ||
> > +	    BTF_INFO_VLEN(st->info) != 2)
> > +		return -EINVAL;
> > +
> > +	/*
> > +	 * The first field must be a 64 bit integer at 0 offset.
> > +	 */
> > +	m = (struct btf_member *)(st + 1);
> > +	t = btf_orig_type(btf, btf_type_by_id(btf, m->type));
> > +	if (!t || BTF_INFO_KIND(t->info) != BTF_KIND_INT || m->offset ||
> > +	    t->size !=
> > +	    FIELD_SIZEOF(struct bpf_cgroup_storage_key, cgroup_inode_id))
> Instead of t->size,
> BTF_INT_BITS() and BTF_INT_OFFSET() need to be checked (please refer to the
> key_type check in array_map_check_btf()).

Gotcha.

> 
> I think exposing "btf_type_int_is_regular()" from btf.c will be easier here.
> Actually, add "btf_type_is_reg_int(t, expected_size)" to btf.h and btf.c,
> like (uncompiled and untested code):

> 
> /*
>  * Not a bit field and it must be the expected size.
>  */
> bool btf_type_is_reg_int(const struct btf_type *t, u32 expected_size)
> {
>  	u8 nr_bits, nr_bytes;
>         u32 int_data;
> 
> 	if (!btf_type_is_int(t))
> 		return false;
> 
> 	int_data = btf_type_int(t);
> 	nr_bits = BTF_INT_BITS(int_data);
> 	nr_bytes = BITS_ROUNDUP_BYTES(nr_bits);
> 	if (BITS_PER_BYTE_MASKED(nr_bits) ||
> 	    BTF_INT_OFFSET(int_data) ||
> 	    nr_bytes != expected_size)
>                 return false;
> 
> 	return true;
> }

Looks good to me. Will implement in v2.

Thanks!

Re: [PATCH bpf-next 2/3] bpf: add bpffs pretty print for cgroup local storage maps

[Roman Gushchin]

On Fri, Dec 07, 2018 at 07:37:35PM -0800, Yonghong Song wrote:
> 
> 
> On 12/7/18 4:53 PM, Roman Gushchin wrote:
> > Implement bpffs pretty printing for cgroup local storage maps
> > (both shared and per-cpu).
> > Output example (captured for tools/testing/selftests/bpf/netcnt_prog.c):
> > 
> > Shared:
> >    $ cat /sys/fs/bpf/map_2
> >    # WARNING!! The output is for debug purpose only
> >    # WARNING!! The output format will change
> >    {4294968594,1}: {9999,1039896}
> > 
> > Per-cpu:
> >    $ cat /sys/fs/bpf/map_1
> >    # WARNING!! The output is for debug purpose only
> >    # WARNING!! The output format will change
> >    {4294968594,1}: {
> >    	cpu0: {0,0,0,0,0}
> >    	cpu1: {0,0,0,0,0}
> >    	cpu2: {1,104,0,0,0}
> >    	cpu3: {0,0,0,0,0}
> >    }
> > 
> > Signed-off-by: Roman Gushchin <guro@fb.com>
> > Cc: Alexei Starovoitov <ast@kernel.org>
> > Cc: Daniel Borkmann <daniel@iogearbox.net>
> > ---
> >   include/linux/btf.h        | 10 +++++
> >   kernel/bpf/local_storage.c | 90 +++++++++++++++++++++++++++++++++++++-
> >   2 files changed, 99 insertions(+), 1 deletion(-)
> > 
> > diff --git a/include/linux/btf.h b/include/linux/btf.h
> > index 8c2199b5d250..ac67bc4cbfd9 100644
> > --- a/include/linux/btf.h
> > +++ b/include/linux/btf.h
> > @@ -5,6 +5,7 @@
> >   #define _LINUX_BTF_H 1
> >   
> >   #include <linux/types.h>
> > +#include <uapi/linux/btf.h>
> >   
> >   struct btf;
> >   struct btf_type;
> > @@ -63,4 +64,13 @@ static inline const char *btf_name_by_offset(const struct btf *btf,
> >   }
> >   #endif
> >   
> > +static inline const struct btf_type *btf_orig_type(const struct btf *btf,
> > +						   const struct btf_type *t)
> > +{
> > +	while (t && BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF)
> > +		t = btf_type_by_id(btf, t->type);
> technically, type modifier "const" and "volatile" can apply to member 
> type as well. But these modifiers really don't make sense here.
> Could you add a comment here to mention that they will be treated
> as an error since such a programming is not really recommended?

Switched over to btf_type_id_size() based on Martin's suggestion.

> 
> > +
> > +	return t;
> > +}
> > +
> >   #endif
> > diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
> > index b65017dead44..7b51fe1aba3c 100644
> > --- a/kernel/bpf/local_storage.c
> > +++ b/kernel/bpf/local_storage.c
> > @@ -1,11 +1,13 @@
> >   //SPDX-License-Identifier: GPL-2.0
> >   #include <linux/bpf-cgroup.h>
> >   #include <linux/bpf.h>
> > +#include <linux/btf.h>
> >   #include <linux/bug.h>
> >   #include <linux/filter.h>
> >   #include <linux/mm.h>
> >   #include <linux/rbtree.h>
> >   #include <linux/slab.h>
> > +#include <uapi/linux/btf.h>
> >   
> >   DEFINE_PER_CPU(struct bpf_cgroup_storage*, bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
> >   
> > @@ -308,6 +310,91 @@ static int cgroup_storage_delete_elem(struct bpf_map *map, void *key)
> >   	return -EINVAL;
> >   }
> >   
> > +static int cgroup_storage_check_btf(const struct bpf_map *map,
> > +				    const struct btf *btf,
> > +				    const struct btf_type *key_type,
> > +				    const struct btf_type *value_type)
> > +{
> > +	const struct btf_type *st, *t;
> > +	struct btf_member *m;
> > +
> > +	/* Key is expected to be of struct bpf_cgroup_storage_key type,
> > +	 * which is:
> > +	 * struct bpf_cgroup_storage_key {
> > +	 *	__u64	cgroup_inode_id;
> > +	 *	__u32	attach_type;
> > +	 * };
> > +	 */
> > +
> > +	/*
> > +	 * Key_type must be a structure (or a typedef of a structure) with
> > +	 * two members.
> > +	 */
> > +	st = btf_orig_type(btf, key_type);
> > +	if (BTF_INFO_KIND(st->info) != BTF_KIND_STRUCT ||
> > +	    BTF_INFO_VLEN(st->info) != 2)
> > +		return -EINVAL;
> > +
> > +	/*
> > +	 * The first field must be a 64 bit integer at 0 offset.
> > +	 */
> > +	m = (struct btf_member *)(st + 1);
> > +	t = btf_orig_type(btf, btf_type_by_id(btf, m->type));
> > +	if (!t || BTF_INFO_KIND(t->info) != BTF_KIND_INT || m->offset ||
> > +	    t->size !=
> > +	    FIELD_SIZEOF(struct bpf_cgroup_storage_key, cgroup_inode_id))
> > +		return -EINVAL;
> 
> We should not use t->size here. The "t->size" is the type size, and the
> real number of bits held by the member is BTF_INT_BITS(...) with the 
> argument of the u32 int value after "t".
> 
> > +
> > +	/*
> > +	 * The second field must be a 32 bit integer at 0 offset.
> > +	 */
> > +	m = m + 1;
> > +	t = btf_orig_type(btf, btf_type_by_id(btf, m->type));
> > +	if (!t || BTF_INFO_KIND(t->info) != BTF_KIND_INT ||
> > +	    m->offset != offsetof(struct bpf_cgroup_storage_key, attach_type) *
> > +	    BITS_PER_BYTE || t->size !=
> > +	    FIELD_SIZEOF(struct bpf_cgroup_storage_key, attach_type))
> > +		return -EINVAL;
> 
> The same is here. t->size should not be used.
> BTF_INT_BITS(...) should be used.

Fixed in v2, which I'll send soon.

Thank you for the review!