diff mbox series

[RFC,bpf-next,v2,12/17] bpf: implement query for target_proto and file dumper prog_id

Message ID 20200415192754.4083756-1-yhs@fb.com
State New
Headers show
Series bpf: implement bpf based dumping of kernel data structures | expand

Commit Message

Yonghong Song April 15, 2020, 7:27 p.m. UTC
Given a fd representing a bpfdump target, user
can retrieve the target_proto name which represents
the bpf program prototype.

Given a fd representing a file dumper, user can
retrieve the bpf_prog id associated with that dumper.

Signed-off-by: Yonghong Song <yhs@fb.com>
---
 include/linux/bpf.h            |  2 +
 include/uapi/linux/bpf.h       | 11 +++++-
 kernel/bpf/dump.c              | 72 ++++++++++++++++++++++++++++++++++
 kernel/bpf/syscall.c           |  2 +-
 tools/include/uapi/linux/bpf.h | 11 +++++-
 5 files changed, 95 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 401e5bf921a2..a1ae8509e735 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1138,6 +1138,8 @@  int bpf_prog_dump_create(struct bpf_prog *prog);
 struct bpf_prog *bpf_dump_get_prog(struct seq_file *seq, u32 priv_data_size,
 				   u64 *session_id, u64 *seq_num, bool is_last);
 int bpf_dump_run_prog(struct bpf_prog *prog, void *ctx);
+int bpf_dump_query(const union bpf_attr *attr, union bpf_attr __user *uattr);
+
 int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value);
 int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value);
 int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value,
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 75f3657d526c..856e3f8a63b8 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -533,7 +533,10 @@  union bpf_attr {
 	};
 
 	struct { /* anonymous struct used by BPF_OBJ_GET_INFO_BY_FD */
-		__u32		bpf_fd;
+		union {
+			__u32		bpf_fd;
+			__u32		dump_query_fd;
+		};
 		__u32		info_len;
 		__aligned_u64	info;
 	} info;
@@ -3618,6 +3621,12 @@  struct bpf_btf_info {
 	__u32 id;
 } __attribute__((aligned(8)));
 
+struct bpf_dump_info {
+	__aligned_u64 prog_ctx_type_name;
+	__u32 type_name_buf_len;
+	__u32 prog_id;
+} __attribute__((aligned(8)));
+
 /* User bpf_sock_addr struct to access socket fields and sockaddr struct passed
  * by user and intended to be used by socket (e.g. to bind to, depends on
  * attach attach type).
diff --git a/kernel/bpf/dump.c b/kernel/bpf/dump.c
index 789b35772a81..643591bf5aea 100644
--- a/kernel/bpf/dump.c
+++ b/kernel/bpf/dump.c
@@ -93,6 +93,78 @@  static void *get_extra_priv_dptr(void *old_ptr, u32 old_size)
 	return old_ptr + roundup(old_size, 8);
 }
 
+int bpf_dump_query(const union bpf_attr *attr, union bpf_attr __user *uattr)
+{
+	struct bpf_dump_info __user *ubpf_dinfo;
+	struct bpfdump_target_info *tinfo;
+	struct dumper_inode_info *i_info;
+	struct bpf_dump_info bpf_dinfo;
+	const char *prog_ctx_type_name;
+	void * __user tname_buf;
+	u32 tname_len, info_len;
+	struct file *filp;
+	struct fd qfd;
+	int err = 0;
+
+	qfd = fdget(attr->info.dump_query_fd);
+	filp = qfd.file;
+	if (!filp)
+		return -EBADF;
+
+	if (filp->f_op != &bpf_dumper_ops &&
+	    filp->f_inode->i_op != &bpfdump_dir_iops) {
+		err = -EINVAL;
+		goto done;
+	}
+
+	info_len = attr->info.info_len;
+	ubpf_dinfo = u64_to_user_ptr(attr->info.info);
+	err = bpf_check_uarg_tail_zero(ubpf_dinfo, sizeof(bpf_dinfo),
+				       info_len);
+	if (err)
+		goto done;
+	info_len = min_t(u32, sizeof(bpf_dinfo), info_len);
+
+	memset(&bpf_dinfo, 0, sizeof(bpf_dinfo));
+	if (copy_from_user(&bpf_dinfo, ubpf_dinfo, info_len)) {
+		err = -EFAULT;
+		goto done;
+	}
+
+	/* copy prog_id for dumpers */
+	if (filp->f_op == &bpf_dumper_ops) {
+		i_info = filp->f_inode->i_private;
+		bpf_dinfo.prog_id = i_info->prog->aux->id;
+		tinfo = i_info->tinfo;
+	} else {
+		tinfo = filp->f_inode->i_private;
+	}
+
+	prog_ctx_type_name = tinfo->prog_ctx_type_name;
+
+	tname_len = strlen(prog_ctx_type_name) + 1;
+	if (bpf_dinfo.type_name_buf_len < tname_len) {
+		err = -ENOSPC;
+		goto done;
+	}
+
+	/* copy prog_ctx_type_name */
+	tname_buf = u64_to_user_ptr(bpf_dinfo.prog_ctx_type_name);
+	if (copy_to_user(tname_buf, prog_ctx_type_name, tname_len)) {
+		err = -EFAULT;
+		goto done;
+	}
+
+	/* copy potentially updated bpf_dinfo and info_len */
+	if (copy_to_user(ubpf_dinfo, &bpf_dinfo, info_len) ||
+	    put_user(info_len, &uattr->info.info_len))
+		return -EFAULT;
+
+done:
+	fdput(qfd);
+	return err;
+}
+
 #ifdef CONFIG_PROC_FS
 static void dumper_show_fdinfo(struct seq_file *m, struct file *filp)
 {
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index e6a4514435c4..1cde78e53a17 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3358,7 +3358,7 @@  static int bpf_obj_get_info_by_fd(const union bpf_attr *attr,
 	else if (f.file->f_op == &btf_fops)
 		err = bpf_btf_get_info_by_fd(f.file->private_data, attr, uattr);
 	else
-		err = -EINVAL;
+		err = bpf_dump_query(attr, uattr);
 
 	fdput(f);
 	return err;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 75f3657d526c..856e3f8a63b8 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -533,7 +533,10 @@  union bpf_attr {
 	};
 
 	struct { /* anonymous struct used by BPF_OBJ_GET_INFO_BY_FD */
-		__u32		bpf_fd;
+		union {
+			__u32		bpf_fd;
+			__u32		dump_query_fd;
+		};
 		__u32		info_len;
 		__aligned_u64	info;
 	} info;
@@ -3618,6 +3621,12 @@  struct bpf_btf_info {
 	__u32 id;
 } __attribute__((aligned(8)));
 
+struct bpf_dump_info {
+	__aligned_u64 prog_ctx_type_name;
+	__u32 type_name_buf_len;
+	__u32 prog_id;
+} __attribute__((aligned(8)));
+
 /* User bpf_sock_addr struct to access socket fields and sockaddr struct passed
  * by user and intended to be used by socket (e.g. to bind to, depends on
  * attach attach type).