From adf2da9becde422bdaf0d223c27cd50193aa7d23 Mon Sep 17 00:00:00 2001
From: Abhishek Vijeev <abhishek.vijeev@gmail.com>
Date: Fri, 24 Jul 2020 17:18:32 +0530
Subject: [PATCH] criu: parse information about BPF maps from procfs

This commit enables CRIU to:
(a) identify an anonymous inode as being a BPF map
(b) parse information about BPF maps from procfs

Source files modified:

* files.c - Checks anonymous inodes to see whether they are BPF maps.
If so, sets struct fdtype_ops *ops to a structure that knows how to
dump BPF maps

* proc_parse.c - Function parse_fdinfo_pid_s() now checks whether the
current file being processed is a BPF map. If so, it calls a newly
defined function parse_bpfmap() which knows how to parse information
about BPF maps from procfs

Signed-off-by: Abhishek Vijeev <abhishek.vijeev@gmail.com>
---
 criu/files.c      |  5 ++++
 criu/proc_parse.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+)

diff --git a/criu/files.c b/criu/files.c
index 2cfc9040e..45105f673 100644
--- a/criu/files.c
+++ b/criu/files.c
@@ -48,6 +48,7 @@
 #include "string.h"
 #include "kerndat.h"
 #include "fdstore.h"
+#include "bpfmap.h"
 
 #include "protobuf.h"
 #include "util.h"
@@ -539,6 +540,10 @@ static int dump_one_file(struct pid *pid, int fd, int lfd, struct fd_opts *opts,
 			ops = &signalfd_dump_ops;
 		else if (is_timerfd_link(link))
 			ops = &timerfd_dump_ops;
+#ifdef CONFIG_HAS_LIBBPF
+		else if (is_bpfmap_link(link))
+			ops = &bpfmap_dump_ops;
+#endif
 		else
 			return dump_unsupp_fd(&p, lfd, "anon", link, e);
 
diff --git a/criu/proc_parse.c b/criu/proc_parse.c
index 77f1b216c..7473bcf67 100644
--- a/criu/proc_parse.c
+++ b/criu/proc_parse.c
@@ -1682,6 +1682,57 @@ nodata:
 	goto parse_err;
 }
 
+typedef struct bpfmap_fmt {
+	char *fmt;
+	void *value;
+} bpfmap_fmt;
+
+static int parse_bpfmap(struct bfd *f, char *str, BpfmapFileEntry *bpf)
+{
+	/*
+	 * Format is:
+	 * 
+	 * uint32_t map_type
+	 * uint32_t key_size
+	 * uint32_t value_size
+	 * uint32_t max_entries
+	 * uint32_t map_flags
+	 * uint64_t memlock
+	 * uint32_t map_id
+	 * boolean frozen
+	 */
+
+	bpfmap_fmt map[] = {
+		{"map_type: %u", &bpf->map_type },
+		{"key_size: %u", &bpf->key_size },
+		{"value_size: %u", &bpf->value_size },
+		{"max_entries: %u", &bpf->max_entries },
+		{"map_flags: %"PRIx32"", &bpf->map_flags },
+		{"memlock: %"PRIu64"", &bpf->memlock },
+		{"map_id: %u", &bpf->map_id },
+		{"frozen: %d", &bpf->frozen },
+	};
+
+	size_t n = sizeof(map) / sizeof(bpfmap_fmt);
+	int i;
+	
+	for (i = 0; i < n; i++) {
+		if (sscanf(str, map[i].fmt, map[i].value) != 1)
+			return -1;
+
+		if (i == n - 1)
+			break;
+
+		str = breadline(f);
+		if (IS_ERR_OR_NULL(str)) {
+			pr_err("No data left in proc file while parsing bpfmap\n");
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
 #define fdinfo_field(str, field)	!strncmp(str, field":", sizeof(field))
 
 static int parse_file_lock_buf(char *buf, struct file_lock *fl,
@@ -2014,6 +2065,18 @@ static int parse_fdinfo_pid_s(int pid, int fd, int type, void *arg)
 			entry_met = true;
 			continue;
 		}
+		if (fdinfo_field(str, "map_type")) {
+			BpfmapFileEntry *bpf = arg;
+			if (type != FD_TYPES__BPFMAP)
+				goto parse_err;
+
+			ret = parse_bpfmap(&f, str, bpf);
+			if (ret)
+				goto parse_err;
+
+			entry_met = true;
+			continue;
+		}
 	}
 
 	exit_code = 0;