From 18126b647a43ff8fbb127cc036084110ac302d32 Mon Sep 17 00:00:00 2001
From: Vitaliy Gusev <gusev.vitaliy@gmail.com>
Date: Fri, 28 Apr 2023 09:00:48 +0200
Subject: [PATCH] bhyve: use directory file descriptor for checkpoint

This is required to enable capsicum for the snapshot code.

Reviewed by:		corvink
Sponsored by:		vStack
Differential Revision:	https://reviews.freebsd.org/D38858
---
 usr.sbin/bhyve/snapshot.c    | 21 ++++++++++++++-------
 usr.sbin/bhyvectl/bhyvectl.c | 25 +++++++++++++++++++++++--
 2 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/usr.sbin/bhyve/snapshot.c b/usr.sbin/bhyve/snapshot.c
index 866fc265b8aa..6d543c1b37e3 100644
--- a/usr.sbin/bhyve/snapshot.c
+++ b/usr.sbin/bhyve/snapshot.c
@@ -1308,9 +1308,10 @@ vm_vcpu_resume(struct vmctx *ctx)
 }
 
 static int
-vm_checkpoint(struct vmctx *ctx, const char *checkpoint_file, bool stop_vm)
+vm_checkpoint(struct vmctx *ctx, int fddir, const char *checkpoint_file,
+    bool stop_vm)
 {
-	int fd_checkpoint = 0, kdata_fd = 0;
+	int fd_checkpoint = 0, kdata_fd = 0, fd_meta;
 	int ret = 0;
 	int error = 0;
 	size_t memsz;
@@ -1325,14 +1326,14 @@ vm_checkpoint(struct vmctx *ctx, const char *checkpoint_file, bool stop_vm)
 		return (-1);
 	}
 
-	kdata_fd = open(kdata_filename, O_WRONLY | O_CREAT | O_TRUNC, 0700);
+	kdata_fd = openat(fddir, kdata_filename, O_WRONLY | O_CREAT | O_TRUNC, 0700);
 	if (kdata_fd < 0) {
 		perror("Failed to open kernel data snapshot file.");
 		error = -1;
 		goto done;
 	}
 
-	fd_checkpoint = open(checkpoint_file, O_RDWR | O_CREAT | O_TRUNC, 0700);
+	fd_checkpoint = openat(fddir, checkpoint_file, O_RDWR | O_CREAT | O_TRUNC, 0700);
 
 	if (fd_checkpoint < 0) {
 		perror("Failed to create checkpoint file");
@@ -1346,9 +1347,12 @@ vm_checkpoint(struct vmctx *ctx, const char *checkpoint_file, bool stop_vm)
 		goto done;
 	}
 
-	meta_file = fopen(meta_filename, "w");
+	fd_meta = openat(fddir, meta_filename, O_WRONLY | O_CREAT | O_TRUNC, 0700);
+	if (fd_meta != -1)
+		meta_file = fdopen(fd_meta, "w");
 	if (meta_file == NULL) {
 		perror("Failed to open vm metadata snapshot file.");
+		close(fd_meta);
 		goto done;
 	}
 
@@ -1474,10 +1478,13 @@ vm_do_checkpoint(struct vmctx *ctx, const nvlist_t *nvl)
 	int error;
 
 	if (!nvlist_exists_string(nvl, "filename") ||
-	    !nvlist_exists_bool(nvl, "suspend"))
+	    !nvlist_exists_bool(nvl, "suspend") ||
+	    !nvlist_exists_descriptor(nvl, "fddir"))
 		error = EINVAL;
 	else
-		error = vm_checkpoint(ctx, nvlist_get_string(nvl, "filename"),
+		error = vm_checkpoint(ctx,
+		    nvlist_get_descriptor(nvl, "fddir"),
+		    nvlist_get_string(nvl, "filename"),
 		    nvlist_get_bool(nvl, "suspend"));
 
 	return (error);
diff --git a/usr.sbin/bhyvectl/bhyvectl.c b/usr.sbin/bhyvectl/bhyvectl.c
index 5c3440ce8343..12f92eb8d96d 100644
--- a/usr.sbin/bhyvectl/bhyvectl.c
+++ b/usr.sbin/bhyvectl/bhyvectl.c
@@ -1711,14 +1711,35 @@ send_message(const char *vmname, nvlist_t *nvl)
 }
 
 static int
-snapshot_request(const char *vmname, const char *file, bool suspend)
+open_directory(const char *file)
+{
+	char *path;
+	int fd;
+
+	if ((path = strdup(file)) == NULL)
+		return (-1);
+
+	dirname(path);
+	fd = open(path, O_DIRECTORY);
+	free(path);
+
+	return (fd);
+}
+
+static int
+snapshot_request(const char *vmname, char *file, bool suspend)
 {
 	nvlist_t *nvl;
+	int fd;
+
+	if ((fd = open_directory(file)) < 0)
+		return (errno);
 
 	nvl = nvlist_create(0);
 	nvlist_add_string(nvl, "cmd", "checkpoint");
-	nvlist_add_string(nvl, "filename", file);
+	nvlist_add_string(nvl, "filename", basename(file));
 	nvlist_add_bool(nvl, "suspend", suspend);
+	nvlist_move_descriptor(nvl, "fddir", fd);
 
 	return (send_message(vmname, nvl));
 }