X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=udev_node.c;h=fcd52d0e45d5d9b861a353267bfbf5c56d64f64c;hp=1632c2cc3ce8823a27deeaece3c3cc6618c02b11;hb=14c7994263150b01d7ffbf89969cf8e3df893dc8;hpb=456cb387567da8a2beadf003dcbd874022dbc873

diff --git a/udev_node.c b/udev_node.c
index 1632c2cc3..fcd52d0e4 100644
--- a/udev_node.c
+++ b/udev_node.c
@@ -25,6 +25,7 @@
 #include <unistd.h>
 #include <errno.h>
 #include <grp.h>
+#include <dirent.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 
@@ -32,9 +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;
 
@@ -43,28 +46,37 @@ int udev_node_mknod(struct udevice *udev, const char *file, dev_t devt, mode_t m
 	else
 		mode |= S_IFCHR;
 
-	if (stat(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;
 	}
 
@@ -83,18 +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])) {
@@ -109,31 +122,196 @@ 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("preserving 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 '%s' will not overwrite it", node, slink);
+					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)
+{
+	LIST_HEAD(name_list);
+	char slink[PATH_SIZE];
+	char node[PATH_SIZE];
+	struct udevice *udev_db;
+	struct name_entry *device;
+	char target[PATH_MAX] = "";
+	int count;
+	int priority = 0;
+	int rc = 0;
+
+	strlcpy(slink, udev_root, sizeof(slink));
+	strlcat(slink, "/", sizeof(slink));
+	strlcat(slink, name, sizeof(slink));
+
+	count = udev_db_get_devices_by_name(name, &name_list);
+	info("found %i devices with name '%s'", count, name);
+
+	/* if we don't have a reference, delete it */
+	if (count <= 0) {
+		info("no reference left, remove '%s'", name);
+		if (!udev->test_run) {
+			unlink(slink);
+			delete_path(slink);
+		}
+		goto out;
+	}
+
+	/* find the device with the highest priority */
+	list_for_each_entry(device, &name_list, node) {
+		info("found '%s' for '%s'", device->name, name);
+
+		/* did we find ourself? we win, if we have the same priority */
+		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) {
+				priority = udev->link_priority;
+				strlcpy(target, udev->name, sizeof(target));
+			}
+			continue;
+		}
+
+		/* or something else, then 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));
+			}
+		}
+		udev_device_cleanup(udev_db);
+	}
+	name_list_cleanup(&name_list);
+
+	if (target[0] == '\0') {
+		err("missing target for '%s'", name);
+		rc = -1;
+		goto out;
+	}
+
+	/* create symlink to the target with the highest priority */
+	strlcpy(node, udev_root, sizeof(node));
+	strlcat(node, "/", sizeof(node));
+	strlcat(node, target, sizeof(node));
+	info("'%s' with target '%s' has the highest priority %i, create it", name, target, priority);
+	if (!udev->test_run) {
+		create_path(slink);
+		node_symlink(node, slink);
+	}
+out:
+	return rc;
+}
+
+void udev_node_update_symlinks(struct udevice *udev, struct udevice *udev_old)
+{
+	struct name_entry *name_loop;
+	char symlinks[PATH_SIZE] = "";
+
+	list_for_each_entry(name_loop, &udev->symlink_list, node) {
+		info("update symlink '%s' of '%s'", name_loop->name, udev->dev->devpath);
+		update_link(udev, name_loop->name);
+		strlcat(symlinks, udev_root, sizeof(symlinks));
+		strlcat(symlinks, "/", sizeof(symlinks));
+		strlcat(symlinks, name_loop->name, sizeof(symlinks));
+		strlcat(symlinks, " ", sizeof(symlinks));
+	}
+
+	/* export symlinks to environment */
+	remove_trailing_chars(symlinks, ' ');
+	if (symlinks[0] != '\0')
+		setenv("DEVLINKS", symlinks, 1);
+
+	/* update possible left-over symlinks (device metadata changed) */
+	if (udev_old != NULL) {
+		struct name_entry *link_loop;
+		struct name_entry *link_old_loop;
+		int found;
+
+		/* remove current symlinks from old list */
+		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) {
+					found = 1;
+					break;
+				}
+			}
+			if (!found) {
+				/* link does no longer belong to this device */
+				info("update old symlink '%s' no longer belonging to '%s'",
+				     link_old_loop->name, udev->dev->devpath);
+				update_link(udev, link_old_loop->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);
+	}
 }
 
-int udev_node_add(struct udevice *udev, struct udevice *udev_old)
+int udev_node_add(struct udevice *udev)
 {
 	char filename[PATH_SIZE];
 	uid_t uid;
@@ -141,10 +319,9 @@ int udev_node_add(struct udevice *udev, struct udevice *udev_old)
 	int i;
 	int retval = 0;
 
-	snprintf(filename, sizeof(filename), "%s/%s", udev_root, udev->name);
-	filename[sizeof(filename)-1] = '\0';
-
-	/* create parent directories if needed */
+	strlcpy(filename, udev_root, sizeof(filename));
+	strlcat(filename, "/", sizeof(filename));
+	strlcat(filename, udev->name, sizeof(filename));
 	create_path(filename);
 
 	if (strcmp(udev->owner, "root") == 0)
@@ -173,7 +350,7 @@ int udev_node_add(struct udevice *udev, struct udevice *udev_old)
 			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)
@@ -192,7 +369,7 @@ int udev_node_add(struct udevice *udev, struct udevice *udev_old)
 
 		/* 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;
@@ -209,114 +386,21 @@ int udev_node_add(struct udevice *udev, struct udevice *udev_old)
 			}
 		}
 	}
-
-	/* create symlink(s) if requested */
-	if (!list_empty(&udev->symlink_list)) {
-		struct name_entry *name_loop;
-		char symlinks[PATH_SIZE] = "";
-
-		list_for_each_entry(name_loop, &udev->symlink_list, node) {
-			char slink[PATH_SIZE];
-
-			strlcpy(slink, udev_root, sizeof(slink));
-			strlcat(slink, "/", sizeof(slink));
-			strlcat(slink, name_loop->name, sizeof(slink));
-
-			info("creating symlink '%s' to node '%s'", slink, filename);
-			if (!udev->test_run) {
-				create_path(slink);
-				node_symlink(filename, slink);
-			}
-
-			strlcat(symlinks, slink, sizeof(symlinks));
-			strlcat(symlinks, " ", sizeof(symlinks));
-		}
-
-		remove_trailing_chars(symlinks, ' ');
-		setenv("DEVLINKS", symlinks, 1);
-	}
-
 exit:
 	return retval;
 }
 
-void udev_node_remove_symlinks(struct udevice *udev)
-{
-	char filename[PATH_SIZE];
-	struct name_entry *name_loop;
-	struct stat stats;
-
-	if (!list_empty(&udev->symlink_list)) {
-		char symlinks[PATH_SIZE] = "";
-
-		list_for_each_entry(name_loop, &udev->symlink_list, node) {
-			char devpath[PATH_SIZE];
-
-			snprintf(filename, sizeof(filename), "%s/%s", udev_root, name_loop->name);
-			filename[sizeof(filename)-1] = '\0';
-
-			if (stat(filename, &stats) != 0) {
-				dbg("symlink '%s' not found", filename);
-				continue;
-			}
-			if (udev->devt && stats.st_rdev != udev->devt) {
-				info("symlink '%s' points to a different device, skip removal", filename);
-				continue;
-			}
-
-			info("removing symlink '%s'", filename);
-			if (!udev->test_run) {
-				unlink(filename);
-				delete_path(filename);
-			}
-
-			/* see if another device wants this symlink */
-			if (udev_db_lookup_name(name_loop->name, devpath, sizeof(devpath)) == 0) {
-				struct udevice *old;
-
-				info("found overwritten symlink '%s' of '%s'", name_loop->name, devpath);
-				old = udev_device_init();
-				if (old != NULL) {
-					if (udev_db_get_device(old, devpath) == 0) {
-						char slink[PATH_SIZE];
-						char node[PATH_SIZE];
-
-						strlcpy(slink, udev_root, sizeof(slink));
-						strlcat(slink, "/", sizeof(slink));
-						strlcat(slink, name_loop->name, sizeof(slink));
-						strlcpy(node, udev_root, sizeof(node));
-						strlcat(node, "/", sizeof(node));
-						strlcat(node, old->name, sizeof(node));
-						info("restore symlink '%s' to '%s'", slink, node);
-						if (!udev->test_run)
-							node_symlink(node, slink);
-					}
-					udev_device_cleanup(old);
-				}
-			}
-
-			strlcat(symlinks, filename, sizeof(symlinks));
-			strlcat(symlinks, " ", sizeof(symlinks));
-		}
-
-		remove_trailing_chars(symlinks, ' ');
-		if (symlinks[0] != '\0')
-			setenv("DEVLINKS", symlinks, 1);
-	}
-}
-
 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;
 
-	udev_node_remove_symlinks(udev);
-
-	snprintf(filename, sizeof(filename), "%s/%s", udev_root, udev->name);
-	filename[sizeof(filename)-1] = '\0';
+	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;
@@ -327,7 +411,8 @@ 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;
 
@@ -337,14 +422,13 @@ int udev_node_remove(struct udevice *udev)
 		int i;
 
 		info("removing all_partitions '%s[1-%i]'", filename, num);
-		if (num > 255) {
-			info("garbage from udev database, skip all_partitions removal");
+		if (num > 255)
 			return -1;
-		}
 		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);