X-Git-Url: https://git.saurik.com/apple/xnu.git/blobdiff_plain/c18c124eaa464aaaa5549e99e5a70fc9cbb50944..3e170ce000f1506b7b5d2c5c7faec85ceabb573d:/bsd/vfs/vfs_lookup.c?ds=inline

diff --git a/bsd/vfs/vfs_lookup.c b/bsd/vfs/vfs_lookup.c
index 4beff12a6..09bd470a9 100644
--- a/bsd/vfs/vfs_lookup.c
+++ b/bsd/vfs/vfs_lookup.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000-2011 Apple Inc. All rights reserved.
+ * Copyright (c) 2000-2015 Apple Inc. All rights reserved.
  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  * 
@@ -90,7 +90,7 @@
 #include <sys/kauth.h>
 #include <kern/kalloc.h>
 #include <security/audit/audit.h>
-
+#include <sys/dtrace.h>        /* to get the prototype for strstr() in sys/dtrace_glue.h */
 #if CONFIG_MACF
 #include <security/mac_framework.h>
 #endif
@@ -371,6 +371,7 @@ retry_copy:
 		if ( (error = lookup(ndp)) ) {
 			goto error_out;
 		}
+
 		/*
 		 * Check for symbolic link
 		 */
@@ -633,15 +634,6 @@ lookup_handle_found_vnode(struct nameidata *ndp, struct componentname *cnp, int
 		goto nextname;
 	}
 
-#if CONFIG_TRIGGERS
-	if (dp->v_resolve) {
-		error = vnode_trigger_resolve(dp, ndp, ctx);
-		if (error) {
-			goto out;
-		}
-	}
-#endif /* CONFIG_TRIGGERS */
-
 	/*
 	 * Take into account any additional components consumed by
 	 * the underlying filesystem.
@@ -1315,73 +1307,90 @@ lookup_traverse_mountpoints(struct nameidata *ndp, struct componentname *cnp, vn
 	uint32_t depth = 0;
 	vnode_t	mounted_on_dp;
 	int current_mount_generation = 0;
+#if CONFIG_TRIGGERS
+	vnode_t triggered_dp = NULLVP;
+	int retry_cnt = 0;
+#define MAX_TRIGGER_RETRIES 1
+#endif
 	
-	mounted_on_dp = dp;
-	current_mount_generation = mount_generation;
-
-	while ((dp->v_type == VDIR) && dp->v_mountedhere &&
-			((cnp->cn_flags & NOCROSSMOUNT) == 0)) {
+	if (dp->v_type != VDIR || cnp->cn_flags & NOCROSSMOUNT)
+		return 0;
 
-		if (dp->v_mountedhere->mnt_lflag & MNT_LFORCE) {
-			break;	// don't traverse into a forced unmount
-		}
+	mounted_on_dp = dp;
 #if CONFIG_TRIGGERS
-		/*
-		 * For a trigger vnode, call its resolver when crossing its mount (if requested)
-		 */
-		if (dp->v_resolve) {
-			(void) vnode_trigger_resolve(dp, ndp, ctx);
-		}
+restart:
 #endif
-		vnode_lock(dp);
-
-		if ((dp->v_type == VDIR) && (mp = dp->v_mountedhere)) {
+	current_mount_generation = mount_generation;
 
+	while (dp->v_mountedhere) {
+		vnode_lock_spin(dp);
+		if ((mp = dp->v_mountedhere)) {
 			mp->mnt_crossref++;
 			vnode_unlock(dp);
+		} else {
+			vnode_unlock(dp);
+			break;
+		}
 
+		if (ISSET(mp->mnt_lflag, MNT_LFORCE)) {
+			mount_dropcrossref(mp, dp, 0);
+			break;	// don't traverse into a forced unmount
+		}
 
-			if (vfs_busy(mp, vbusyflags)) {
-				mount_dropcrossref(mp, dp, 0);
-				if (vbusyflags == LK_NOWAIT) {
-					error = ENOENT;
-					goto out;
-				}
-
-				continue;
-			}
-
-			error = VFS_ROOT(mp, &tdp, ctx);
 
+		if (vfs_busy(mp, vbusyflags)) {
 			mount_dropcrossref(mp, dp, 0);
-			vfs_unbusy(mp);
-
-			if (error) {
+			if (vbusyflags == LK_NOWAIT) {
+				error = ENOENT;
 				goto out;
 			}
 
-			vnode_put(dp);
-			ndp->ni_vp = dp = tdp;
-			depth++;
+			continue;
+		}
+
+		error = VFS_ROOT(mp, &tdp, ctx);
 
-#if CONFIG_TRIGGERS
-			/*
-			 * Check if root dir is a trigger vnode
-			 */
-			if (dp->v_resolve) {
-				error = vnode_trigger_resolve(dp, ndp, ctx);
-				if (error) {
-					goto out;
-				}
-			}
-#endif			
+		mount_dropcrossref(mp, dp, 0);
+		vfs_unbusy(mp);
 
-		} else { 
-			vnode_unlock(dp);
+		if (error) {
+			goto out;
+		}
+
+		vnode_put(dp);
+		ndp->ni_vp = dp = tdp;
+		if (dp->v_type != VDIR) {
+#if DEVELOPMENT || DEBUG
+			panic("%s : Root of filesystem not a directory\n",
+			    __FUNCTION__);
+#else
 			break;
+#endif
 		}
+		depth++;
 	}
 
+#if CONFIG_TRIGGERS
+	/*
+	 * The triggered_dp check here is required but is susceptible to a
+	 * (unlikely) race in which trigger mount is done from here and is
+	 * unmounted before we get past vfs_busy above. We retry to deal with
+	 * that case but it has the side effect of unwanted retries for
+	 * "special" processes which don't want to trigger mounts.
+	 */
+	if (dp->v_resolve && retry_cnt < MAX_TRIGGER_RETRIES) {
+		error = vnode_trigger_resolve(dp, ndp, ctx);
+		if (error)
+			goto out;
+		if (dp == triggered_dp)
+			retry_cnt += 1;
+		else
+			retry_cnt = 0;
+		triggered_dp = dp;
+		goto restart;
+	}
+#endif /* CONFIG_TRIGGERS */
+
 	if (depth) {
 	        mp = mounted_on_dp->v_mountedhere;