bpf: Add name, load_time, uid and map_ids to bpf_prog_info

The patch adds name and load_time to struct bpf_prog_aux.  They
are also exported to bpf_prog_info.

The bpf_prog's name is passed by userspace during BPF_PROG_LOAD.
The kernel only stores the first (BPF_PROG_NAME_LEN - 1) bytes
and the name stored in the kernel is always \0 terminated.

The kernel will reject name that contains characters other than
isalnum() and '_'.  It will also reject name that is not null
terminated.

The existing 'user->uid' of the bpf_prog_aux is also exported to
the bpf_prog_info as created_by_uid.

The existing 'used_maps' of the bpf_prog_aux is exported to
the newly added members 'nr_map_ids' and 'map_ids' of
the bpf_prog_info.  On the input, nr_map_ids tells how
big the userspace's map_ids buffer is.  On the output,
nr_map_ids tells the exact user_map_cnt and it will only
copy up to the userspace's map_ids buffer is allowed.

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

1 files changed, 50 insertions, 1 deletions

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 25d074920a00..45970df3f820 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -23,6 +23,9 @@
 #include <linux/version.h>
 #include <linux/kernel.h>
 #include <linux/idr.h>
+#include <linux/cred.h>
+#include <linux/timekeeping.h>
+#include <linux/ctype.h>
 
 #define IS_FD_ARRAY(map) ((map)->map_type == BPF_MAP_TYPE_PROG_ARRAY || \
 			   (map)->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY || \
@@ -312,6 +315,30 @@ int bpf_map_new_fd(struct bpf_map *map)
 		   offsetof(union bpf_attr, CMD##_LAST_FIELD) - \
 		   sizeof(attr->CMD##_LAST_FIELD)) != NULL
 
+/* dst and src must have at least BPF_OBJ_NAME_LEN number of bytes.
+ * Return 0 on success and < 0 on error.
+ */
+static int bpf_obj_name_cpy(char *dst, const char *src)
+{
+	const char *end = src + BPF_OBJ_NAME_LEN;
+
+	/* Copy all isalnum() and '_' char */
+	while (src < end && *src) {
+		if (!isalnum(*src) && *src != '_')
+			return -EINVAL;
+		*dst++ = *src++;
+	}
+
+	/* No '\0' found in BPF_OBJ_NAME_LEN number of bytes */
+	if (src == end)
+		return -EINVAL;
+
+	/* '\0' terminates dst */
+	*dst = 0;
+
+	return 0;
+}
+
 #define BPF_MAP_CREATE_LAST_FIELD numa_node
 /* called via syscall */
 static int map_create(union bpf_attr *attr)
@@ -973,7 +1000,7 @@ struct bpf_prog *bpf_prog_get_type(u32 ufd, enum bpf_prog_type type)
 EXPORT_SYMBOL_GPL(bpf_prog_get_type);
 
 /* last field in 'union bpf_attr' used by this command */
-#define	BPF_PROG_LOAD_LAST_FIELD prog_flags
+#define	BPF_PROG_LOAD_LAST_FIELD prog_name
 
 static int bpf_prog_load(union bpf_attr *attr)
 {
@@ -1037,6 +1064,11 @@ static int bpf_prog_load(union bpf_attr *attr)
 	if (err < 0)
 		goto free_prog;
 
+	prog->aux->load_time = ktime_get_boot_ns();
+	err = bpf_obj_name_cpy(prog->aux->name, attr->prog_name);
+	if (err)
+		goto free_prog;
+
 	/* run eBPF verifier */
 	err = bpf_check(&prog, attr);
 	if (err < 0)
@@ -1358,8 +1390,25 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
 
 	info.type = prog->type;
 	info.id = prog->aux->id;
+	info.load_time = prog->aux->load_time;
+	info.created_by_uid = from_kuid_munged(current_user_ns(),
+					       prog->aux->user->uid);
 
 	memcpy(info.tag, prog->tag, sizeof(prog->tag));
+	memcpy(info.name, prog->aux->name, sizeof(prog->aux->name));
+
+	ulen = info.nr_map_ids;
+	info.nr_map_ids = prog->aux->used_map_cnt;
+	ulen = min_t(u32, info.nr_map_ids, ulen);
+	if (ulen) {
+		u32 *user_map_ids = (u32 *)info.map_ids;
+		u32 i;
+
+		for (i = 0; i < ulen; i++)
+			if (put_user(prog->aux->used_maps[i]->id,
+				     &user_map_ids[i]))
+				return -EFAULT;
+	}
 
 	if (!capable(CAP_SYS_ADMIN)) {
 		info.jited_prog_len = 0;