Dump and restore sigactions (v2)

A parasite code dumps all sigactions in sigact.pid.

v2: remove hard code for sizeof(sigset_t)
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>

cr-dump.c

@@ -1106,6 +1106,12 @@ static int dump_one_task(pid_t pid, struct cr_fdset *cr_fdset)
 		goto err;
 	}
 
+	ret = parasite_dump_sigacts_seized(parasite_ctl, cr_fdset);
+	if (ret) {
+		pr_err("Can't dump sigactions (pid: %d) with parasite\n", pid);
+		goto err;
+	}
+
 	ret = parasite_cure_seized(&parasite_ctl, &vma_area_list);
 	if (ret) {
 		pr_err("Can't cure (pid: %d) from parasite\n", pid);

cr-restore.c

@@ -1030,6 +1030,44 @@ static int open_pipe(int pid, struct pipe_entry *e, int *pipes_fd)
 		return attach_pipe(pid, e, pi, *pipes_fd);
 }
 
+static int prepare_sigactions(int pid)
+{
+	int fd_sigact, ret;
+	int sig, i;
+	struct sigaction act, oact;
+
+	fd_sigact = open_fmt_ro(FMT_FNAME_SIGACTS, pid);
+	if (fd_sigact < 0) {
+		pr_perror("%d: Can't open sigactions img\n", pid);
+		return 1;
+	}
+
+	for (sig = 1; sig < SIGMAX; sig++) {
+		if (sig == SIGKILL || sig == SIGSTOP)
+			continue;
+
+		ret = read(fd_sigact, &act, sizeof(act));
+		if (ret != sizeof(act)) {
+			pr_err("%d: Bad sigaction entry: %d (%m)\n", pid, ret);
+			ret = -1;
+			goto err;
+		}
+
+		/* A pure syscall is used, because a glibc
+		 * sigaction overwrite se_restorer */
+		ret = sys_sigaction(sig, &act, &oact);
+		if (ret == -1) {
+			pr_err("%d: Can't restore sigaction: %m\n", pid);
+			goto err;
+		}
+	}
+
+err:
+	close(fd_sigact);
+	return ret;
+}
+
+
 static int prepare_pipes(int pid)
 {
 	int pipes_fd;
@@ -1084,6 +1122,9 @@ static int restore_one_task(int pid)
 	if (prepare_shmem(pid))
 		return 1;
 
+	if (prepare_sigactions(pid))
+		return 1;
+
 	return prepare_and_sigreturn(pid);
 }
 

crtools.c

@@ -79,6 +79,12 @@ struct cr_fd_desc_tmpl fdset_template[CR_FD_MAX] = {
 		.fmt	= FMT_FNAME_SHMEM,
 		.magic	= SHMEM_MAGIC,
 	},
+
+	/* info about which memory areas are shared */
+	[CR_FD_SIGACT] = {
+		.fmt	= FMT_FNAME_SIGACTS,
+		.magic	= SIGACT_MAGIC,
+	},
 };
 
 struct cr_fdset *alloc_cr_fdset(pid_t pid)

include/crtools.h

@@ -21,6 +21,7 @@ enum {
 	CR_FD_PIPES,
 	CR_FD_PSTREE,
 	CR_FD_SHMEM,
+	CR_FD_SIGACT,
 
 	CR_FD_MAX
 };
@@ -51,6 +52,7 @@ struct cr_fd_desc_tmpl {
 #define FMT_FNAME_PSTREE	"pstree-%d.img"
 #define FMT_FNAME_SHMEM		"shmem-%d.img"
 #define FMT_FNAME_VMAS		"vmas-%d.img"
+#define FMT_FNAME_SIGACTS	"sigacts-%d.img"
 
 /* file descriptors */
 struct cr_fd_desc {

include/image.h

@@ -11,6 +11,7 @@
 #define PIPEFS_MAGIC	0x50495045
 #define PSTREE_MAGIC	0x40044004
 #define PIPES_MAGIC	0x05055050
+#define SIGACT_MAGIC	0x60606060
 
 #define FDINFO_FD	1
 #define FDINFO_MAP	2

include/parasite-syscall.h

@@ -38,6 +38,7 @@ int syscall_seized(pid_t pid,
 
 int parasite_dump_pages_seized(struct parasite_ctl *ctl, struct list_head *vma_area_list,
 			       struct cr_fdset *cr_fdset, int fd_type);
+int parasite_dump_sigacts_seized(struct parasite_ctl *ctl, struct cr_fdset *cr_fdset);
 
 struct parasite_ctl *parasite_infect_seized(pid_t pid, void *addr_hint, struct list_head *vma_area_list);
 int parasite_cure_seized(struct parasite_ctl **p_ctrl, struct list_head *vma_area_list);

include/parasite.h

@@ -22,12 +22,14 @@
 #define PARASITE_ERR_CLOSE	-1029
 #define PARASITE_ERR_WRITE	-1030
 #define PARASITE_ERR_MPROTECT	-1031
+#define PARASITE_ERR_SIGACTION  -1032
 
 enum {
 	PARASITE_CMD_NONE,
 	PARASITE_CMD_KILLME,
 	PARASITE_CMD_PINGME,
 	PARASITE_CMD_DUMPPAGES,
+	PARASITE_CMD_DUMP_SIGACTS,
 
 	PARASITE_CMD_MAX,
 };
@@ -54,6 +56,13 @@ typedef struct {
 	char			open_path[256];
 } parasite_args_cmd_dumppages_t;
 
+typedef struct {
+	parasite_status_t	status;
+	unsigned long		open_mode;
+	unsigned long		open_flags;
+	char			open_path[256];
+} parasite_args_cmd_dumpsigacts_t;
+
 /*
  * Some useful offsets
  */

include/restorer.h

@@ -149,10 +149,6 @@ typedef struct rt_siginfo {
 	int	_pad[SI_PAD_SIZE];
 } rt_siginfo_t;
 
-typedef struct {
-	unsigned long sig[1];
-} rt_sigset_t;
-
 typedef struct rt_sigaltstack {
 	void	*ss_sp;
 	int	ss_flags;

include/syscall-codes.h

@@ -12,6 +12,7 @@
 #define __NR_mprotect		10
 #define __NR_munmap		11
 #define __NR_brk		12
+#define __NR_rt_sigaction	13
 #define __NR_rt_sigreturn	15
 #define __NR_mincore		27
 #define __NR_dup		32

include/syscall.h

@@ -9,6 +9,10 @@
 
 #ifdef CONFIG_X86_64
 
+typedef struct {
+	unsigned long sig[1];
+} rt_sigset_t;
+
 static always_inline long syscall0(int nr)
 {
 	long ret;
@@ -152,6 +156,13 @@ static always_inline long sys_open(const char *filename, unsigned long flags, un
 	return syscall3(__NR_open, (unsigned long)filename, flags, mode);
 }
 
+struct sigaction;
+
+static always_inline long sys_sigaction(int signum, const struct sigaction *act, struct sigaction *oldact)
+{
+	return syscall4(__NR_rt_sigaction, signum, (unsigned long) act, (unsigned long) oldact, sizeof(rt_sigset_t));
+}
+
 static always_inline long sys_close(int fd)
 {
 	return syscall1(__NR_close, fd);

include/types.h

@@ -74,6 +74,8 @@
 #define CLONE_CHILD_USEPID      0x02000000
 #define CLONE_VFORK		0x00004000
 
+#define SIGMAX			32
+
 typedef uint64_t		u64;
 typedef int64_t			s64;
 typedef unsigned int		u32;

parasite-syscall.c

@@ -340,6 +340,58 @@ err:
 	return ret;
 }
 
+int parasite_dump_sigacts_seized(struct parasite_ctl *ctl, struct cr_fdset *cr_fdset)
+{
+	parasite_args_cmd_dumpsigacts_t parasite_sigacts	= { };
+
+	int status, path_len, ret = -1;
+	char *cwd = NULL;
+
+	pr_info("\n");
+	pr_info("Dumping sigactions (pid: %d)\n", ctl->pid);
+	pr_info("----------------------------------------\n");
+
+	cwd = get_current_dir_name();
+	if (!cwd) {
+		pr_err("No memory to obtain cwd\n");
+		goto out;
+	}
+
+	path_len = strlen(cr_fdset->desc[CR_FD_SIGACT].name) +
+			strlen(cwd) + 2;
+
+	if (path_len > sizeof(parasite_sigacts.open_path)) {
+		pr_panic("Dumping sigactions path is too long (%d while %d allowed)\n",
+			 path_len, sizeof(parasite_sigacts.open_path));
+		goto out;
+	}
+
+	if (fchmod(cr_fdset->desc[CR_FD_SIGACT].fd, CR_FD_PERM_DUMP)) {
+		pr_perror("Can't change permissions on sigactions file\n");
+		goto out;
+	}
+
+	snprintf(parasite_sigacts.open_path,
+		 sizeof(parasite_sigacts.open_path),
+		"%s/%s", cwd, cr_fdset->desc[CR_FD_SIGACT].name);
+
+	free(cwd);
+
+	parasite_sigacts.open_flags	= O_WRONLY;
+	parasite_sigacts.open_mode	= CR_FD_PERM_DUMP;
+
+	ret = parasite_execute(PARASITE_CMD_DUMP_SIGACTS, ctl,
+				(parasite_status_t *) &parasite_sigacts,
+				sizeof(parasite_sigacts));
+
+err:
+	jerr(fchmod(cr_fdset->desc[CR_FD_SIGACT].fd, CR_FD_PERM), out);
+out:
+	pr_info("----------------------------------------\n");
+
+	return ret;
+}
+
 /*
  * This routine drives parasite code (been previously injected into a victim
  * process) and tells it to dump pages into the file.

parasite.c

@@ -229,6 +229,47 @@ err:
 	return ret;
 }
 
+static int dump_sigact(parasite_args_cmd_dumpsigacts_t *args)
+{
+	int fd;
+	int ret = PARASITE_ERR_FAIL;
+	int sig;
+	struct sigaction act;
+	parasite_status_t *st = &args->status;
+
+	fd = sys_open(args->open_path, args->open_flags, args->open_mode);
+	if (fd < 0) {
+		sys_write_msg("sys_open failed\n");
+		st->ret = PARASITE_ERR_OPEN, st->line = __LINE__;
+		return 1;
+	}
+
+        for (sig = 1; sig < SIGMAX; sig++) {
+		if (sig == SIGKILL || sig == SIGSTOP)
+			continue;
+
+		ret = sys_sigaction(sig, NULL, &act);
+		if (ret < 0) {
+			sys_write_msg("sys_sigaction failed\n");
+			st->ret = PARASITE_ERR_SIGACTION, st->line = __LINE__;
+			goto err_close;
+		}
+
+		ret = sys_write(fd, &act, sizeof(act));
+		if (ret != sizeof(act)) {
+			sys_write_msg("sys_write failed\n");
+			st->sys_ret = ret;
+			st->ret = PARASITE_ERR_WRITE, st->line = __LINE__;
+			ret = -1;
+			goto err_close;
+		}
+	}
+	st->ret = ret = 0, st->line = __LINE__;
+err_close:
+	sys_close(fd);
+	return ret;
+}
+
 static int __used parasite_service(unsigned long cmd, void *args, void *brk)
 {
 	brk_init(brk);
@@ -242,6 +283,9 @@ static int __used parasite_service(unsigned long cmd, void *args, void *brk)
 	case PARASITE_CMD_DUMPPAGES:
 		return dump_pages((parasite_args_cmd_dumppages_t *)args);
 		break;
+	case PARASITE_CMD_DUMP_SIGACTS:
+		return dump_sigact((parasite_args_cmd_dumpsigacts_t *)args);
+		break;
 	default:
 		sys_write_msg("Unknown command to parasite\n");
 		break;