X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=udev_node.c;h=bd58a6c485d9ddc6128bd4d31079ec54ba63fc6e;hp=f30ae876ecd5779ecdd6f86484f3ed3b5dabbdc5;hb=a0092d28dbb2c1c75c2fac17303b703343f03a35;hpb=604f104af43aa40ff07e43179909604a9a780800

diff --git a/udev_node.c b/udev_node.c
index f30ae876e..bd58a6c48 100644
--- a/udev_node.c
+++ b/udev_node.c
@@ -33,9 +33,11 @@
 #include "udev_rules.h"
 #include "udev_selinux.h"
 
+#define TMP_FILE_EXT		".udev-tmp"
 
 int udev_node_mknod(struct udevice *udev, const char *file, dev_t devt, mode_t mode, uid_t uid, gid_t gid)
 {
+	char file_tmp[PATH_SIZE + sizeof(TMP_FILE_EXT)];
 	struct stat stats;
 	int retval = 0;
 
@@ -44,28 +46,37 @@ int udev_node_mknod(struct udevice *udev, const char *file, dev_t devt, mode_t m
 	else
 		mode |= S_IFCHR;
 
-	if (lstat(file, &stats) != 0)
-		goto create;
-
-	/* preserve node with already correct numbers, to prevent changing the inode number */
-	if ((stats.st_mode & S_IFMT) == (mode & S_IFMT) && (stats.st_rdev == devt)) {
-		info("preserve file '%s', because it has correct dev_t", file);
-		selinux_setfilecon(file, udev->dev->kernel, stats.st_mode);
-		goto perms;
+	if (lstat(file, &stats) == 0) {
+		if ((stats.st_mode & S_IFMT) == (mode & S_IFMT) && (stats.st_rdev == devt)) {
+			info("preserve file '%s', because it has correct dev_t", file);
+			selinux_setfilecon(file, udev->dev->kernel, stats.st_mode);
+			goto perms;
+		}
+	} else {
+		selinux_setfscreatecon(file, udev->dev->kernel, mode);
+		retval = mknod(file, mode, devt);
+		selinux_resetfscreatecon();
+		if (retval == 0)
+			goto perms;
 	}
 
-	if (unlink(file) != 0)
-		err("unlink(%s) failed: %s", file, strerror(errno));
-	else
-		dbg("already present file '%s' unlinked", file);
-
-create:
-	selinux_setfscreatecon(file, udev->dev->kernel, mode);
-	retval = mknod(file, mode, devt);
+	info("atomically replace '%s'", file);
+	strlcpy(file_tmp, file, sizeof(file_tmp));
+	strlcat(file_tmp, TMP_FILE_EXT, sizeof(file_tmp));
+	unlink(file_tmp);
+	selinux_setfscreatecon(file_tmp, udev->dev->kernel, mode);
+	retval = mknod(file_tmp, mode, devt);
 	selinux_resetfscreatecon();
 	if (retval != 0) {
 		err("mknod(%s, %#o, %u, %u) failed: %s",
-		    file, mode, major(devt), minor(devt), strerror(errno));
+		    file_tmp, mode, major(devt), minor(devt), strerror(errno));
+		goto exit;
+	}
+	retval = rename(file_tmp, file);
+	if (retval != 0) {
+		err("rename(%s, %s) failed: %s",
+		    file_tmp, file, strerror(errno));
+		unlink(file_tmp);
 		goto exit;
 	}
 
@@ -84,18 +95,19 @@ perms:
 			goto exit;
 		}
 	}
-
 exit:
 	return retval;
 }
 
 static int node_symlink(const char *node, const char *slink)
 {
+	struct stat stats;
 	char target[PATH_SIZE] = "";
-	char buf[PATH_SIZE];
+	char slink_tmp[PATH_SIZE + sizeof(TMP_FILE_EXT)];
 	int i = 0;
 	int tail = 0;
 	int len;
+	int retval = 0;
 
 	/* use relative link */
 	while (node[i] && (node[i] == slink[i])) {
@@ -110,28 +122,63 @@ static int node_symlink(const char *node, const char *slink)
 	}
 	strlcat(target, &node[tail], sizeof(target));
 
-	/* look if symlink already exists */
-	len = readlink(slink, buf, sizeof(buf));
-	if (len > 0) {
-		buf[len] = '\0';
-		if (strcmp(target, buf) == 0) {
-			info("preserve already existing symlink '%s' to '%s'", slink, target);
-			selinux_setfilecon(slink, NULL, S_IFLNK);
-			goto exit;
+	/* preserve link with correct target, do not replace node of other device */
+	if (lstat(slink, &stats) == 0) {
+		if (S_ISBLK(stats.st_mode) || S_ISCHR(stats.st_mode)) {
+			struct stat stats2;
+
+			info("found existing node instead of symlink '%s'", slink);
+			if (lstat(node, &stats2) == 0) {
+				if ((stats.st_mode & S_IFMT) == (stats2.st_mode & S_IFMT) &&
+				    stats.st_rdev == stats2.st_rdev) {
+					info("replace device node '%s' with symlink to our node '%s'", slink, node);
+				} else {
+					err("device node '%s' already exists, link to '%s' will not overwrite it", slink, node);
+					goto exit;
+				}
+			}
+		} else if (S_ISLNK(stats.st_mode)) {
+			char buf[PATH_SIZE];
+
+			info("found existing symlink '%s'", slink);
+			len = readlink(slink, buf, sizeof(buf));
+			if (len > 0) {
+				buf[len] = '\0';
+				if (strcmp(target, buf) == 0) {
+					info("preserve already existing symlink '%s' to '%s'", slink, target);
+					selinux_setfilecon(slink, NULL, S_IFLNK);
+					goto exit;
+				}
+			}
 		}
-		info("link '%s' points to different target '%s', delete it", slink, buf);
-		unlink(slink);
+	} else {
+		info("creating symlink '%s' to '%s'", slink, target);
+		selinux_setfscreatecon(slink, NULL, S_IFLNK);
+		retval = symlink(target, slink);
+		selinux_resetfscreatecon();
+		if (retval == 0)
+			goto exit;
 	}
 
-	/* create link */
-	info("creating symlink '%s' to '%s'", slink, target);
-	selinux_setfscreatecon(slink, NULL, S_IFLNK);
-	if (symlink(target, slink) != 0)
-		err("symlink(%s, %s) failed: %s", target, slink, strerror(errno));
+	info("atomically replace '%s'", slink);
+	strlcpy(slink_tmp, slink, sizeof(slink_tmp));
+	strlcat(slink_tmp, TMP_FILE_EXT, sizeof(slink_tmp));
+	unlink(slink_tmp);
+	selinux_setfscreatecon(slink_tmp, NULL, S_IFLNK);
+	retval = symlink(target, slink_tmp);
 	selinux_resetfscreatecon();
-
+	if (retval != 0) {
+		err("symlink(%s, %s) failed: %s", target, slink_tmp, strerror(errno));
+		goto exit;
+	}
+	retval = rename(slink_tmp, slink);
+	if (retval != 0) {
+		err("rename(%s, %s) failed: %s", slink_tmp, slink, strerror(errno));
+		unlink(slink_tmp);
+		goto exit;
+	}
 exit:
-	return 0;
+	return retval;
 }
 
 static int update_link(struct udevice *udev, const char *name)
@@ -153,7 +200,7 @@ static int update_link(struct udevice *udev, const char *name)
 	count = udev_db_get_devices_by_name(name, &name_list);
 	info("found %i devices with name '%s'", count, name);
 
-	/* if we don't have any reference, we can delete the link */
+	/* if we don't have a reference, delete it */
 	if (count <= 0) {
 		info("no reference left, remove '%s'", name);
 		if (!udev->test_run) {
@@ -171,23 +218,29 @@ static int update_link(struct udevice *udev, const char *name)
 		if (strcmp(udev->dev->devpath, device->name) == 0) {
 			info("compare (our own) priority of '%s' %i >= %i",
 			     udev->dev->devpath, udev->link_priority, priority);
-			if (target[0] == '\0' || udev->link_priority >= priority) {
+			if (strcmp(udev->name, name) == 0) {
+				info("'%s' is our device node, database inconsistent, skip link update", udev->name);
+			} else if (target[0] == '\0' || udev->link_priority >= priority) {
 				priority = udev->link_priority;
 				strlcpy(target, udev->name, sizeof(target));
 			}
 			continue;
 		}
 
-		/* or something else, then read priority from database */
+		/* another device, read priority from database */
 		udev_db = udev_device_init(NULL);
 		if (udev_db == NULL)
 			continue;
 		if (udev_db_get_device(udev_db, device->name) == 0) {
-			info("compare priority of '%s' %i > %i",
-			     udev_db->dev->devpath, udev_db->link_priority, priority);
-			if (target[0] == '\0' || udev_db->link_priority > priority) {
-				priority = udev_db->link_priority;
-				strlcpy(target, udev_db->name, sizeof(target));
+			if (strcmp(udev_db->name, name) == 0) {
+				info("'%s' is a device node of '%s', skip link update", udev_db->name, device->name);
+			} else {
+				info("compare priority of '%s' %i > %i",
+				     udev_db->dev->devpath, udev_db->link_priority, priority);
+				if (target[0] == '\0' || udev_db->link_priority > priority) {
+					priority = udev_db->link_priority;
+					strlcpy(target, udev_db->name, sizeof(target));
+				}
 			}
 		}
 		udev_device_cleanup(udev_db);
@@ -195,8 +248,8 @@ static int update_link(struct udevice *udev, const char *name)
 	name_list_cleanup(&name_list);
 
 	if (target[0] == '\0') {
-		err("missing target for '%s'", name);
-		rc = -1;
+		info("no current target for '%s' found", name);
+		rc = 1;
 		goto out;
 	}
 
@@ -236,11 +289,10 @@ void udev_node_update_symlinks(struct udevice *udev, struct udevice *udev_old)
 	if (udev_old != NULL) {
 		struct name_entry *link_loop;
 		struct name_entry *link_old_loop;
-		struct name_entry *link_old_tmp_loop;
 		int found;
 
 		/* remove current symlinks from old list */
-		list_for_each_entry_safe(link_old_loop, link_old_tmp_loop, &udev_old->symlink_list, node) {
+		list_for_each_entry(link_old_loop, &udev_old->symlink_list, node) {
 			found = 0;
 			list_for_each_entry(link_loop, &udev->symlink_list, node) {
 				if (strcmp(link_old_loop->name, link_loop->name) == 0) {
@@ -256,8 +308,12 @@ void udev_node_update_symlinks(struct udevice *udev, struct udevice *udev_old)
 			}
 		}
 
-		/* the old node is gone, maybe we have a device with a symlink now */
-		update_link(udev, udev_old->name);
+		/*
+		 * if the node name has changed, delete the node,
+		 * or possibly restore a symlink of another device
+		 */
+		if (strcmp(udev->name, udev_old->name) != 0)
+			update_link(udev, udev_old->name);
 	}
 }
 
@@ -300,7 +356,7 @@ int udev_node_add(struct udevice *udev)
 			gid = lookup_group(udev->group);
 	}
 
-	info("creating device node '%s', major = '%d', minor = '%d', " "mode = '%#o', uid = '%d', gid = '%d'",
+	info("creating device node '%s', major=%d, minor=%d, mode=%#o, uid=%d, gid=%d",
 	     filename, major(udev->devt), minor(udev->devt), udev->mode, uid, gid);
 
 	if (!udev->test_run)
@@ -319,7 +375,7 @@ int udev_node_add(struct udevice *udev)
 
 		/* take the maximum registered minor range */
 		attr = sysfs_attr_get_value(udev->dev->devpath, "range");
-		if (attr) {
+		if (attr != NULL) {
 			range = atoi(attr);
 			if (range > 1)
 				udev->partitions = range-1;
@@ -345,15 +401,15 @@ int udev_node_remove(struct udevice *udev)
 	char filename[PATH_SIZE];
 	char partitionname[PATH_SIZE];
 	struct stat stats;
-	int retval;
+	int retval = 0;
 	int num;
 
 	strlcpy(filename, udev_root, sizeof(filename));
 	strlcat(filename, "/", sizeof(filename));
 	strlcat(filename, udev->name, sizeof(filename));
 	if (stat(filename, &stats) != 0) {
-		dbg("device node '%s' not found", filename);
-		return -1;
+		info("device node '%s' not found", filename);
+		return 0;
 	}
 	if (udev->devt && stats.st_rdev != udev->devt) {
 		info("device node '%s' points to a different device, skip removal", filename);
@@ -361,7 +417,8 @@ int udev_node_remove(struct udevice *udev)
 	}
 
 	info("removing device node '%s'", filename);
-	retval = unlink_secure(filename);
+	if (!udev->test_run)
+		retval = unlink_secure(filename);
 	if (retval)
 		return retval;
 
@@ -376,7 +433,8 @@ int udev_node_remove(struct udevice *udev)
 		for (i = 1; i <= num; i++) {
 			snprintf(partitionname, sizeof(partitionname), "%s%d", filename, i);
 			partitionname[sizeof(partitionname)-1] = '\0';
-			unlink_secure(partitionname);
+			if (!udev->test_run)
+				unlink_secure(partitionname);
 		}
 	}
 	delete_path(filename);