Merge branch 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc

[firefly-linux-kernel-4.4.55.git] / fs / namei.c

diff --git a/fs/namei.c b/fs/namei.c
index 8c14353fb7503b6dcdb9922f099c05a1535e73d3..d1895f30815670de8abd8a6c921443035c21a364 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -119,40 +119,69 @@
  */
 void final_putname(struct filename *name)
 {
-       __putname(name->name);
-       kfree(name);
+       if (name->separate) {
+               __putname(name->name);
+               kfree(name);
+       } else {
+               __putname(name);
+       }
 }
 
+#define EMBEDDED_NAME_MAX      (PATH_MAX - sizeof(struct filename))
+
 static struct filename *
 getname_flags(const char __user *filename, int flags, int *empty)
 {
        struct filename *result, *err;
-       char *kname;
        int len;
+       long max;
+       char *kname;
 
        result = audit_reusename(filename);
        if (result)
                return result;
 
-       /* FIXME: create dedicated slabcache? */
-       result = kzalloc(sizeof(*result), GFP_KERNEL);
+       result = __getname();
        if (unlikely(!result))
                return ERR_PTR(-ENOMEM);
 
-       kname = __getname();
-       if (unlikely(!kname)) {
-               err = ERR_PTR(-ENOMEM);
-               goto error_free_name;
-       }
-
+       /*
+        * First, try to embed the struct filename inside the names_cache
+        * allocation
+        */
+       kname = (char *)result + sizeof(*result);
        result->name = kname;
-       result->uptr = filename;
-       len = strncpy_from_user(kname, filename, PATH_MAX);
+       result->separate = false;
+       max = EMBEDDED_NAME_MAX;
+
+recopy:
+       len = strncpy_from_user(kname, filename, max);
        if (unlikely(len < 0)) {
                err = ERR_PTR(len);
                goto error;
        }
 
+       /*
+        * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a
+        * separate struct filename so we can dedicate the entire
+        * names_cache allocation for the pathname, and re-do the copy from
+        * userland.
+        */
+       if (len == EMBEDDED_NAME_MAX && max == EMBEDDED_NAME_MAX) {
+               kname = (char *)result;
+
+               result = kzalloc(sizeof(*result), GFP_KERNEL);
+               if (!result) {
+                       err = ERR_PTR(-ENOMEM);
+                       result = (struct filename *)kname;
+                       goto error;
+               }
+               result->name = kname;
+               result->separate = true;
+               max = PATH_MAX;
+               goto recopy;
+       }
+
        /* The empty path is special. */
        if (unlikely(!len)) {
                if (empty)
@@ -163,15 +192,15 @@ getname_flags(const char __user *filename, int flags, int *empty)
        }
 
        err = ERR_PTR(-ENAMETOOLONG);
-       if (likely(len < PATH_MAX)) {
-               audit_getname(result);
-               return result;
-       }
+       if (unlikely(len >= PATH_MAX))
+               goto error;
+
+       result->uptr = filename;
+       audit_getname(result);
+       return result;
 
 error:
-       __putname(kname);
-error_free_name:
-       kfree(result);
+       final_putname(result);
        return err;
 }
 
@@ -1999,8 +2028,7 @@ static int filename_lookup(int dfd, struct filename *name,
                                                flags | LOOKUP_REVAL, nd);
 
        if (likely(!retval))
-               audit_inode(name->name, nd->path.dentry,
-                                               flags & LOOKUP_PARENT);
+               audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT);
        return retval;
 }
 
@@ -2662,7 +2690,7 @@ out_dput:
  */
 static int do_last(struct nameidata *nd, struct path *path,
                   struct file *file, const struct open_flags *op,
-                  int *opened, const char *pathname)
+                  int *opened, struct filename *name)
 {
        struct dentry *dir = nd->path.dentry;
        int open_flag = op->open_flag;
@@ -2689,7 +2717,7 @@ static int do_last(struct nameidata *nd, struct path *path,
                error = complete_walk(nd);
                if (error)
                        return error;
-               audit_inode(pathname, nd->path.dentry, 0);
+               audit_inode(name, nd->path.dentry, 0);
                if (open_flag & O_CREAT) {
                        error = -EISDIR;
                        goto out;
@@ -2699,7 +2727,7 @@ static int do_last(struct nameidata *nd, struct path *path,
                error = complete_walk(nd);
                if (error)
                        return error;
-               audit_inode(pathname, dir, 0);
+               audit_inode(name, dir, 0);
                goto finish_open;
        }
 
@@ -2728,7 +2756,7 @@ static int do_last(struct nameidata *nd, struct path *path,
                if (error)
                        return error;
 
-               audit_inode(pathname, dir, 0);
+               audit_inode(name, dir, 0);
                error = -EISDIR;
                /* trailing slashes? */
                if (nd->last.name[nd->last.len])
@@ -2758,7 +2786,7 @@ retry_lookup:
                    !S_ISREG(file->f_path.dentry->d_inode->i_mode))
                        will_truncate = false;
 
-               audit_inode(pathname, file->f_path.dentry, 0);
+               audit_inode(name, file->f_path.dentry, 0);
                goto opened;
        }
 
@@ -2775,7 +2803,7 @@ retry_lookup:
         * create/update audit record if it already exists.
         */
        if (path->dentry->d_inode)
-               audit_inode(pathname, path->dentry, 0);
+               audit_inode(name, path->dentry, 0);
 
        /*
         * If atomic_open() acquired write access it is dropped now due to
@@ -2840,7 +2868,7 @@ finish_lookup:
        error = -ENOTDIR;
        if ((nd->flags & LOOKUP_DIRECTORY) && !nd->inode->i_op->lookup)
                goto out;
-       audit_inode(pathname, nd->path.dentry, 0);
+       audit_inode(name, nd->path.dentry, 0);
 finish_open:
        if (!S_ISREG(nd->inode->i_mode))
                will_truncate = false;
@@ -2908,7 +2936,7 @@ stale_open:
        goto retry_lookup;
 }
 
-static struct file *path_openat(int dfd, const char *pathname,
+static struct file *path_openat(int dfd, struct filename *pathname,
                struct nameidata *nd, const struct open_flags *op, int flags)
 {
        struct file *base = NULL;
@@ -2923,12 +2951,12 @@ static struct file *path_openat(int dfd, const char *pathname,
 
        file->f_flags = op->open_flag;
 
-       error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base);
+       error = path_init(dfd, pathname->name, flags | LOOKUP_PARENT, nd, &base);
        if (unlikely(error))
                goto out;
 
        current->total_link_count = 0;
-       error = link_path_walk(pathname, nd);
+       error = link_path_walk(pathname->name, nd);
        if (unlikely(error))
                goto out;
 
@@ -2974,7 +3002,7 @@ out:
        return file;
 }
 
-struct file *do_filp_open(int dfd, const char *pathname,
+struct file *do_filp_open(int dfd, struct filename *pathname,
                const struct open_flags *op, int flags)
 {
        struct nameidata nd;
@@ -2993,6 +3021,7 @@ struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
 {
        struct nameidata nd;
        struct file *file;
+       struct filename filename = { .name = name };
 
        nd.root.mnt = mnt;
        nd.root.dentry = dentry;
@@ -3002,11 +3031,11 @@ struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
        if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN)
                return ERR_PTR(-ELOOP);
 
-       file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU);
+       file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_RCU);
        if (unlikely(file == ERR_PTR(-ECHILD)))
-               file = path_openat(-1, name, &nd, op, flags);
+               file = path_openat(-1, &filename, &nd, op, flags);
        if (unlikely(file == ERR_PTR(-ESTALE)))
-               file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL);
+               file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_REVAL);
        return file;
 }