X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=fs%2Fnamei.c;h=d62fdc875f22800a3d5c1a8c0a2532b0b6d51cc6;hb=6339204ecc2aa2067a99595522de0403f0854bb8;hp=c530e5d32f1282971415749b45fc3a816c16a7c2;hpb=b65a9cfc2c38eebc33533280b8ad5841caee8b6e;p=safe%2Fjmp%2Flinux-2.6

diff --git a/fs/namei.c b/fs/namei.c
index c530e5d..d62fdc8 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -37,8 +37,6 @@
 
 #include "internal.h"
 
-#define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])
-
 /* [Feb-1997 T. Schoebel-Theuer]
  * Fundamental changes in the pathname lookup mechanisms (namei)
  * were necessary because of omirr.  The reason is that omirr needs
@@ -234,6 +232,7 @@ int generic_permission(struct inode *inode, int mask,
 	/*
 	 * Searching includes executable on directories, else just read.
 	 */
+	mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
 	if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE)))
 		if (capable(CAP_DAC_READ_SEARCH))
 			return 0;
@@ -414,6 +413,46 @@ do_revalidate(struct dentry *dentry, struct nameidata *nd)
 }
 
 /*
+ * force_reval_path - force revalidation of a dentry
+ *
+ * In some situations the path walking code will trust dentries without
+ * revalidating them. This causes problems for filesystems that depend on
+ * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set
+ * (which indicates that it's possible for the dentry to go stale), force
+ * a d_revalidate call before proceeding.
+ *
+ * Returns 0 if the revalidation was successful. If the revalidation fails,
+ * either return the error returned by d_revalidate or -ESTALE if the
+ * revalidation it just returned 0. If d_revalidate returns 0, we attempt to
+ * invalidate the dentry. It's up to the caller to handle putting references
+ * to the path if necessary.
+ */
+static int
+force_reval_path(struct path *path, struct nameidata *nd)
+{
+	int status;
+	struct dentry *dentry = path->dentry;
+
+	/*
+	 * only check on filesystems where it's possible for the dentry to
+	 * become stale. It's assumed that if this flag is set then the
+	 * d_revalidate op will also be defined.
+	 */
+	if (!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))
+		return 0;
+
+	status = dentry->d_op->d_revalidate(dentry, nd);
+	if (status > 0)
+		return 0;
+
+	if (!status) {
+		d_invalidate(dentry);
+		status = -ESTALE;
+	}
+	return status;
+}
+
+/*
  * Short-cut version of permission(), for calling on directories
  * during pathname resolution.  Combines parts of permission()
  * and generic_permission(), and tests ONLY for MAY_EXEC permission.
@@ -522,6 +561,7 @@ static __always_inline int __do_follow_link(struct path *path, struct nameidata
 		dget(dentry);
 	}
 	mntget(path->mnt);
+	nd->last_type = LAST_BIND;
 	cookie = dentry->d_inode->i_op->follow_link(dentry, nd);
 	error = PTR_ERR(cookie);
 	if (!IS_ERR(cookie)) {
@@ -529,6 +569,11 @@ static __always_inline int __do_follow_link(struct path *path, struct nameidata
 		error = 0;
 		if (s)
 			error = __vfs_follow_link(nd, s);
+		else if (nd->last_type == LAST_BIND) {
+			error = force_reval_path(&nd->path, nd);
+			if (error)
+				path_put(&nd->path);
+		}
 		if (dentry->d_inode->i_op->put_link)
 			dentry->d_inode->i_op->put_link(dentry, nd, cookie);
 	}
@@ -1559,11 +1604,12 @@ struct file *do_filp_open(int dfd, const char *pathname,
 	struct file *filp;
 	struct nameidata nd;
 	int error;
-	struct path path, save;
+	struct path path;
 	struct dentry *dir;
 	int count = 0;
 	int will_truncate;
 	int flag = open_to_namei_flags(open_flag);
+	int force_reval = 0;
 
 	/*
 	 * O_SYNC is implemented as __O_SYNC|O_DSYNC.  As many places only
@@ -1575,7 +1621,7 @@ struct file *do_filp_open(int dfd, const char *pathname,
 		open_flag |= O_DSYNC;
 
 	if (!acc_mode)
-		acc_mode = MAY_OPEN | ACC_MODE(flag);
+		acc_mode = MAY_OPEN | ACC_MODE(open_flag);
 
 	/* O_TRUNC implies we need access checks for write permissions */
 	if (flag & O_TRUNC)
@@ -1595,6 +1641,7 @@ struct file *do_filp_open(int dfd, const char *pathname,
 		if (filp == NULL)
 			return ERR_PTR(-ENFILE);
 		nd.intent.open.file = filp;
+		filp->f_flags = open_flag;
 		nd.intent.open.flags = flag;
 		nd.intent.open.create_mode = 0;
 		error = do_path_lookup(dfd, pathname,
@@ -1614,9 +1661,12 @@ struct file *do_filp_open(int dfd, const char *pathname,
 	/*
 	 * Create - we need to know the parent.
 	 */
+reval:
 	error = path_init(dfd, pathname, LOOKUP_PARENT, &nd);
 	if (error)
 		return ERR_PTR(error);
+	if (force_reval)
+		nd.flags |= LOOKUP_REVAL;
 	error = path_walk(pathname, &nd);
 	if (error) {
 		if (nd.root.mnt)
@@ -1640,6 +1690,7 @@ struct file *do_filp_open(int dfd, const char *pathname,
 	if (filp == NULL)
 		goto exit_parent;
 	nd.intent.open.file = filp;
+	filp->f_flags = open_flag;
 	nd.intent.open.flags = flag;
 	nd.intent.open.create_mode = mode;
 	dir = nd.path.dentry;
@@ -1680,13 +1731,12 @@ do_last:
 			mnt_drop_write(nd.path.mnt);
 			goto exit;
 		}
-		filp = nameidata_to_filp(&nd, open_flag);
+		filp = nameidata_to_filp(&nd);
 		mnt_drop_write(nd.path.mnt);
 		if (nd.root.mnt)
 			path_put(&nd.root);
 		if (!IS_ERR(filp)) {
-			error = ima_path_check(&filp->f_path, filp->f_mode &
-				       (MAY_READ | MAY_WRITE | MAY_EXEC), 0);
+			error = ima_file_check(filp, acc_mode);
 			if (error) {
 				fput(filp);
 				filp = ERR_PTR(error);
@@ -1719,7 +1769,7 @@ do_last:
 
 	path_to_nameidata(&path, &nd);
 	error = -EISDIR;
-	if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode))
+	if (S_ISDIR(path.dentry->d_inode->i_mode))
 		goto exit;
 ok:
 	/*
@@ -1744,10 +1794,9 @@ ok:
 			mnt_drop_write(nd.path.mnt);
 		goto exit;
 	}
-	filp = nameidata_to_filp(&nd, open_flag);
+	filp = nameidata_to_filp(&nd);
 	if (!IS_ERR(filp)) {
-		error = ima_path_check(&filp->f_path, filp->f_mode &
-			       (MAY_READ | MAY_WRITE | MAY_EXEC), 0);
+		error = ima_file_check(filp, acc_mode);
 		if (error) {
 			fput(filp);
 			filp = ERR_PTR(error);
@@ -1807,17 +1856,7 @@ do_link:
 	error = security_inode_follow_link(path.dentry, &nd);
 	if (error)
 		goto exit_dput;
-	save = nd.path;
-	path_get(&save);
 	error = __do_follow_link(&path, &nd);
-	if (error == -ESTALE) {
-		/* nd.path had been dropped */
-		nd.path = save;
-		path_get(&nd.path);
-		nd.flags |= LOOKUP_REVAL;
-		error = __do_follow_link(&path, &nd);
-	}
-	path_put(&save);
 	path_put(&path);
 	if (error) {
 		/* Does someone understand code flow here? Or it is only
@@ -1827,6 +1866,10 @@ do_link:
 		release_open_intent(&nd);
 		if (nd.root.mnt)
 			path_put(&nd.root);
+		if (error == -ESTALE && !force_reval) {
+			force_reval = 1;
+			goto reval;
+		}
 		return ERR_PTR(error);
 	}
 	nd.flags &= ~LOOKUP_PARENT;