criu: Add support for pidfds

criu/Makefile.crtools

@@ -101,6 +101,7 @@ obj-$(CONFIG_COMPAT)	+= vdso-compat.o
 CFLAGS_REMOVE_vdso-compat.o	+= $(CFLAGS-ASAN) $(CFLAGS-GCOV)
 obj-y			+= pidfd-store.o
 obj-y			+= hugetlb.o
+obj-y			+= pidfd.o
 
 PROTOBUF_GEN := scripts/protobuf-gen.sh
 

criu/cr-restore.c

@@ -79,6 +79,7 @@
 #include "timens.h"
 #include "bpfmap.h"
 #include "apparmor.h"
+#include "pidfd.h"
 
 #include "parasite-syscall.h"
 #include "files-reg.h"
@@ -277,10 +278,10 @@
 };
 
 static struct collect_image_info *cinfos_files[] = {
 	&unix_sk_cinfo,	      &fifo_cinfo,     &pipe_cinfo,    &nsfile_cinfo,	    &packet_sk_cinfo,
 	&netlink_sk_cinfo,    &eventfd_cinfo,  &epoll_cinfo,   &epoll_tfd_cinfo,    &signalfd_cinfo,
 	&tunfile_cinfo,	      &timerfd_cinfo,  &inotify_cinfo, &inotify_mark_cinfo, &fanotify_cinfo,
-	&fanotify_mark_cinfo, &ext_file_cinfo, &memfd_cinfo,
+	&fanotify_mark_cinfo, &ext_file_cinfo, &memfd_cinfo, &pidfd_cinfo
 };
 
 /* These images are required to restore namespaces */

criu/files.c

@@ -49,6 +49,7 @@
 #include "kerndat.h"
 #include "fdstore.h"
 #include "bpfmap.h"
+#include "pidfd.h"
 
 #include "protobuf.h"
 #include "util.h"
@@ -544,6 +545,8 @@ 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;
+		else if (is_pidfd_link(link))
+			ops = &pidfd_dump_ops;
 #ifdef CONFIG_HAS_LIBBPF
 		else if (is_bpfmap_link(link))
 			ops = &bpfmap_dump_ops;
@@ -554,6 +557,11 @@ static int dump_one_file(struct pid *pid, int fd, int lfd, struct fd_opts *opts,
 		return do_dump_gen_file(&p, lfd, ops, e);
 	}
 
+	if (p.fs_type == PID_FS_MAGIC) {
+		ops = &pidfd_dump_ops;
+		return do_dump_gen_file(&p, lfd, ops, e);
+	}
+
 	if (S_ISREG(p.stat.st_mode) || S_ISDIR(p.stat.st_mode) || S_ISLNK(p.stat.st_mode)) {
 		if (fill_fdlink(lfd, &p, &link))
 			return -1;
@@ -1778,6 +1786,9 @@ static int collect_one_file(void *o, ProtobufCMessage *base, struct cr_img *i)
 	case FD_TYPES__MEMFD:
 		ret = collect_one_file_entry(fe, fe->memfd->id, &fe->memfd->base, &memfd_cinfo);
 		break;
+	case FD_TYPES__PIDFD:
+		ret = collect_one_file_entry(fe, fe->pidfd->id, &fe->pidfd->base, &pidfd_cinfo);
+		break;
 #ifdef CONFIG_HAS_LIBBPF
 	case FD_TYPES__BPFMAP:
 		ret = collect_one_file_entry(fe, fe->bpf->id, &fe->bpf->base, &bpfmap_cinfo);
@@ -1800,5 +1811,11 @@ int prepare_files(void)
 {
 	init_fdesc_hash();
 	init_sk_info_hash();
+
+	if (init_dead_pidfd_hash()) {
+		pr_err("Could not initialise hash map for dead pidfds\n");
+		return -1;
+	}
+
 	return collect_image(&files_cinfo);
 }

criu/image-desc.c

@@ -25,7 +25,7 @@
 	}
 
 struct cr_fd_desc_tmpl imgset_template[CR_FD_MAX] = {
 	FD_ENTRY(INVENTORY,	"inventory"),
 	FD_ENTRY(FDINFO,	"fdinfo-%u"),
 	FD_ENTRY(PAGEMAP,	"pagemap-%lu"),
 	FD_ENTRY(SHMEM_PAGEMAP,	"pagemap-shmem-%lu"),
@@ -107,6 +107,7 @@
 	FD_ENTRY_F(BPFMAP_FILE,	"bpfmap-file", O_NOBUF),
 	FD_ENTRY_F(BPFMAP_DATA,	"bpfmap-data", O_NOBUF),
 	FD_ENTRY(APPARMOR,	"apparmor"),
+	FD_ENTRY(PIDFD,		"pidfd"),
 
 	[CR_FD_STATS] = {
 		.fmt	= "stats-%s",

criu/include/fs-magic.h

@@ -57,4 +57,8 @@
 #define OVERLAYFS_SUPER_MAGIC 0x794c7630
 #endif
 
+#ifndef PID_FS_MAGIC
+#define PID_FS_MAGIC 0x50494446
+#endif
+
 #endif /* __CR_FS_MAGIC_H__ */

criu/include/image-desc.h

@@ -113,6 +113,7 @@ enum {
 	CR_FD_PIPES,
 	CR_FD_TTY_FILES,
 	CR_FD_MEMFD_FILE,
+	CR_FD_PIDFD,
 
 	CR_FD_AUTOFS,
 

criu/include/magic.h

@@ -100,6 +100,7 @@
 #define BPFMAP_FILE_MAGIC    0x57506142 /* Alapayevsk */
 #define BPFMAP_DATA_MAGIC    0x64324033 /* Arkhangelsk */
 #define APPARMOR_MAGIC	     0x59423047 /* Nikolskoye */
+#define PIDFD_MAGIC	     0x54435556 /* Ufa */
 
 #define IFADDR_MAGIC	RAW_IMAGE_MAGIC
 #define ROUTE_MAGIC	RAW_IMAGE_MAGIC

criu/include/pidfd.h

@@ -0,0 +1,16 @@
+#ifndef __CR_PIDFD_H__
+#define __CR_PIDFD_H__
+
+#include "files.h"
+#include "pidfd.pb-c.h"
+
+extern const struct fdtype_ops pidfd_dump_ops;
+extern struct collect_image_info pidfd_cinfo;
+extern int is_pidfd_link(char *link);
+extern int init_dead_pidfd_hash(void);
+struct pidfd_dump_info {
+	PidfdEntry pidfe;
+	pid_t pid;
+};
+
+#endif /* __CR_PIDFD_H__ */

criu/include/protobuf-desc.h

@@ -70,6 +70,7 @@ enum {
 	PB_BPFMAP_FILE,
 	PB_BPFMAP_DATA,
 	PB_APPARMOR,
+	PB_PIDFD,
 
 	/* PB_AUTOGEN_STOP */