[PATCH net-next 0/3] bpf: Misc improvements and a new usage on bpf obj name

[PATCH net-next 0/3] bpf: Misc improvements and a new usage on bpf obj name

[Martin KaFai Lau]

The first two patches make improvements on the bpf obj name.

The last patch adds the prog name to kallsyms.

Martin KaFai Lau (3):
  bpf: Change bpf_obj_name_cpy() to better ensure map's name is init by
    0
  bpf: Use char in prog and map name
  bpf: Append prog->aux->name in bpf_get_prog_name()

 include/linux/bpf.h            |  4 ++--
 include/uapi/linux/bpf.h       |  8 ++++----
 kernel/bpf/core.c              | 17 +++++++++++++++--
 kernel/bpf/syscall.c           |  5 ++---
 tools/include/uapi/linux/bpf.h |  8 ++++----
 5 files changed, 27 insertions(+), 15 deletions(-)

-- 
2.9.5

[PATCH net-next 1/3] bpf: Change bpf_obj_name_cpy() to better ensure map's name is init by 0

[Martin KaFai Lau]

During get_info_by_fd, the prog/map name is memcpy-ed.  It depends
on the prog->aux->name and map->name to be zero initialized.

bpf_prog_aux is easy to guarantee that aux->name is zero init.

The name in bpf_map may be harder to be guaranteed in the future when
new map type is added.

Hence, this patch makes bpf_obj_name_cpy() to always zero init
the prog/map name.

Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
---
 kernel/bpf/syscall.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 0048cb24ba7b..d124e702e040 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -322,6 +322,8 @@ static int bpf_obj_name_cpy(char *dst, const char *src)
 {
 	const char *end = src + BPF_OBJ_NAME_LEN;
 
+	memset(dst, 0, BPF_OBJ_NAME_LEN);
+
 	/* Copy all isalnum() and '_' char */
 	while (src < end && *src) {
 		if (!isalnum(*src) && *src != '_')
@@ -333,9 +335,6 @@ static int bpf_obj_name_cpy(char *dst, const char *src)
 	if (src == end)
 		return -EINVAL;
 
-	/* '\0' terminates dst */
-	*dst = 0;
-
 	return 0;
 }
 
-- 
2.9.5

[PATCH net-next 2/3] bpf: Use char in prog and map name

[Martin KaFai Lau]

Instead of u8, use char for prog and map name.  It can avoid the
userspace tool getting compiler's signess warning.  The
bpf_prog_aux, bpf_map, bpf_attr, bpf_prog_info and
bpf_map_info are changed.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Cc: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@fb.com>
---
 include/linux/bpf.h            | 4 ++--
 include/uapi/linux/bpf.h       | 8 ++++----
 tools/include/uapi/linux/bpf.h | 8 ++++----
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index a67daea731ab..bc7da2ddfcaf 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -56,7 +56,7 @@ struct bpf_map {
 	struct work_struct work;
 	atomic_t usercnt;
 	struct bpf_map *inner_map_meta;
-	u8 name[BPF_OBJ_NAME_LEN];
+	char name[BPF_OBJ_NAME_LEN];
 };
 
 /* function argument constraints */
@@ -189,7 +189,7 @@ struct bpf_prog_aux {
 	struct bpf_prog *prog;
 	struct user_struct *user;
 	u64 load_time; /* ns since boottime */
-	u8 name[BPF_OBJ_NAME_LEN];
+	char name[BPF_OBJ_NAME_LEN];
 	union {
 		struct work_struct work;
 		struct rcu_head	rcu;
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 6082faf5fd2a..a37ad348c436 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -230,7 +230,7 @@ union bpf_attr {
 		__u32	numa_node;	/* numa node (effective only if
 					 * BPF_F_NUMA_NODE is set).
 					 */
-		__u8	map_name[BPF_OBJ_NAME_LEN];
+		char	map_name[BPF_OBJ_NAME_LEN];
 	};
 
 	struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */
@@ -253,7 +253,7 @@ union bpf_attr {
 		__aligned_u64	log_buf;	/* user supplied buffer */
 		__u32		kern_version;	/* checked when prog_type=kprobe */
 		__u32		prog_flags;
-		__u8		prog_name[BPF_OBJ_NAME_LEN];
+		char		prog_name[BPF_OBJ_NAME_LEN];
 	};
 
 	struct { /* anonymous struct used by BPF_OBJ_* commands */
@@ -869,7 +869,7 @@ struct bpf_prog_info {
 	__u32 created_by_uid;
 	__u32 nr_map_ids;
 	__aligned_u64 map_ids;
-	__u8  name[BPF_OBJ_NAME_LEN];
+	char name[BPF_OBJ_NAME_LEN];
 } __attribute__((aligned(8)));
 
 struct bpf_map_info {
@@ -879,7 +879,7 @@ struct bpf_map_info {
 	__u32 value_size;
 	__u32 max_entries;
 	__u32 map_flags;
-	__u8  name[BPF_OBJ_NAME_LEN];
+	char  name[BPF_OBJ_NAME_LEN];
 } __attribute__((aligned(8)));
 
 /* User bpf_sock_ops struct to access socket values and specify request ops
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index cb2b9f95160a..f75ac330831d 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -230,7 +230,7 @@ union bpf_attr {
 		__u32	numa_node;	/* numa node (effective only if
 					 * BPF_F_NUMA_NODE is set).
 					 */
-		__u8	map_name[BPF_OBJ_NAME_LEN];
+		char	map_name[BPF_OBJ_NAME_LEN];
 	};
 
 	struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */
@@ -253,7 +253,7 @@ union bpf_attr {
 		__aligned_u64	log_buf;	/* user supplied buffer */
 		__u32		kern_version;	/* checked when prog_type=kprobe */
 		__u32		prog_flags;
-		__u8		prog_name[BPF_OBJ_NAME_LEN];
+		char		prog_name[BPF_OBJ_NAME_LEN];
 	};
 
 	struct { /* anonymous struct used by BPF_OBJ_* commands */
@@ -869,7 +869,7 @@ struct bpf_prog_info {
 	__u32 created_by_uid;
 	__u32 nr_map_ids;
 	__aligned_u64 map_ids;
-	__u8  name[BPF_OBJ_NAME_LEN];
+	char  name[BPF_OBJ_NAME_LEN];
 } __attribute__((aligned(8)));
 
 struct bpf_map_info {
@@ -879,7 +879,7 @@ struct bpf_map_info {
 	__u32 value_size;
 	__u32 max_entries;
 	__u32 map_flags;
-	__u8  name[BPF_OBJ_NAME_LEN];
+	char  name[BPF_OBJ_NAME_LEN];
 } __attribute__((aligned(8)));
 
 /* User bpf_sock_ops struct to access socket values and specify request ops
-- 
2.9.5

[PATCH net-next 3/3] bpf: Append prog->aux->name in bpf_get_prog_name()

[Martin KaFai Lau]

This patch makes the bpf_prog's name available
in kallsyms.

The new format is bpf_prog_tag[_name].

Sample kallsyms from running selftests/bpf/test_progs:
[root@arch-fb-vm1 ~]# egrep ' bpf_prog_[0-9a-fA-F]{16}' /proc/kallsyms
ffffffffa0048000 t bpf_prog_dabf0207d1992486_test_obj_id
ffffffffa0038000 t bpf_prog_a04f5eef06a7f555__123456789ABCDE
ffffffffa0050000 t bpf_prog_a04f5eef06a7f555

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@fb.com>
---
 kernel/bpf/core.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index c6be15ae83ee..248961af2421 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -309,12 +309,25 @@ bpf_get_prog_addr_region(const struct bpf_prog *prog,
 
 static void bpf_get_prog_name(const struct bpf_prog *prog, char *sym)
 {
+	const char *end = sym + KSYM_NAME_LEN;
+
 	BUILD_BUG_ON(sizeof("bpf_prog_") +
-		     sizeof(prog->tag) * 2 + 1 > KSYM_NAME_LEN);
+		     sizeof(prog->tag) * 2 +
+		     /* name has been null terminated.
+		      * We should need +1 for the '_' preceding
+		      * the name.  However, the null character
+		      * is double counted between the name and the
+		      * sizeof("bpf_prog_") above, so we omit
+		      * the +1 here.
+		      */
+		     sizeof(prog->aux->name) > KSYM_NAME_LEN);
 
 	sym += snprintf(sym, KSYM_NAME_LEN, "bpf_prog_");
 	sym  = bin2hex(sym, prog->tag, sizeof(prog->tag));
-	*sym = 0;
+	if (prog->aux->name[0])
+		snprintf(sym, (size_t)(end - sym), "_%s", prog->aux->name);
+	else
+		*sym = 0;
 }
 
 static __always_inline unsigned long
-- 
2.9.5

Re: [PATCH net-next 0/3] bpf: Misc improvements and a new usage on bpf obj name

[David Miller]

From: Martin KaFai Lau <kafai@fb.com>
Date: Thu, 5 Oct 2017 21:52:10 -0700

> The first two patches make improvements on the bpf obj name.
> 
> The last patch adds the prog name to kallsyms.

Series applied, thanks Martin.