Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

[uclinux-h8/linux.git] / fs / overlayfs / super.c

diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 84c5e27..7466ff3 100644 (file)
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -273,11 +273,58 @@ static void ovl_dentry_release(struct dentry *dentry)
        }
 }
 
+static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags)
+{
+       struct ovl_entry *oe = dentry->d_fsdata;
+       unsigned int i;
+       int ret = 1;
+
+       for (i = 0; i < oe->numlower; i++) {
+               struct dentry *d = oe->lowerstack[i].dentry;
+
+               if (d->d_flags & DCACHE_OP_REVALIDATE) {
+                       ret = d->d_op->d_revalidate(d, flags);
+                       if (ret < 0)
+                               return ret;
+                       if (!ret) {
+                               if (!(flags & LOOKUP_RCU))
+                                       d_invalidate(d);
+                               return -ESTALE;
+                       }
+               }
+       }
+       return 1;
+}
+
+static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags)
+{
+       struct ovl_entry *oe = dentry->d_fsdata;
+       unsigned int i;
+       int ret = 1;
+
+       for (i = 0; i < oe->numlower; i++) {
+               struct dentry *d = oe->lowerstack[i].dentry;
+
+               if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) {
+                       ret = d->d_op->d_weak_revalidate(d, flags);
+                       if (ret <= 0)
+                               break;
+               }
+       }
+       return ret;
+}
+
 static const struct dentry_operations ovl_dentry_operations = {
        .d_release = ovl_dentry_release,
        .d_select_inode = ovl_d_select_inode,
 };
 
+static const struct dentry_operations ovl_reval_dentry_operations = {
+       .d_release = ovl_dentry_release,
+       .d_revalidate = ovl_dentry_revalidate,
+       .d_weak_revalidate = ovl_dentry_weak_revalidate,
+};
+
 static struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
 {
        size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
@@ -289,6 +336,20 @@ static struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
        return oe;
 }
 
+static bool ovl_dentry_remote(struct dentry *dentry)
+{
+       return dentry->d_flags &
+               (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
+}
+
+static bool ovl_dentry_weird(struct dentry *dentry)
+{
+       return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
+                                 DCACHE_MANAGE_TRANSIT |
+                                 DCACHE_OP_HASH |
+                                 DCACHE_OP_COMPARE);
+}
+
 static inline struct dentry *ovl_lookup_real(struct dentry *dir,
                                             struct qstr *name)
 {
@@ -304,6 +365,10 @@ static inline struct dentry *ovl_lookup_real(struct dentry *dir,
        } else if (!dentry->d_inode) {
                dput(dentry);
                dentry = NULL;
+       } else if (ovl_dentry_weird(dentry)) {
+               dput(dentry);
+               /* Don't support traversing automounts and other weirdness */
+               dentry = ERR_PTR(-EREMOTE);
        }
        return dentry;
 }
@@ -351,6 +416,11 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
                        goto out;
 
                if (this) {
+                       if (unlikely(ovl_dentry_remote(this))) {
+                               dput(this);
+                               err = -EREMOTE;
+                               goto out;
+                       }
                        if (ovl_is_whiteout(this)) {
                                dput(this);
                                this = NULL;
@@ -530,7 +600,7 @@ static int ovl_remount(struct super_block *sb, int *flags, char *data)
 {
        struct ovl_fs *ufs = sb->s_fs_info;
 
-       if (!(*flags & MS_RDONLY) && !ufs->upper_mnt)
+       if (!(*flags & MS_RDONLY) && (!ufs->upper_mnt || !ufs->workdir))
                return -EROFS;
 
        return 0;
@@ -695,25 +765,6 @@ static void ovl_unescape(char *s)
        }
 }
 
-static bool ovl_is_allowed_fs_type(struct dentry *root)
-{
-       const struct dentry_operations *dop = root->d_op;
-
-       /*
-        * We don't support:
-        *  - automount filesystems
-        *  - filesystems with revalidate (FIXME for lower layer)
-        *  - filesystems with case insensitive names
-        */
-       if (dop &&
-           (dop->d_manage || dop->d_automount ||
-            dop->d_revalidate || dop->d_weak_revalidate ||
-            dop->d_compare || dop->d_hash)) {
-               return false;
-       }
-       return true;
-}
-
 static int ovl_mount_dir_noesc(const char *name, struct path *path)
 {
        int err = -EINVAL;
@@ -728,7 +779,7 @@ static int ovl_mount_dir_noesc(const char *name, struct path *path)
                goto out;
        }
        err = -EINVAL;
-       if (!ovl_is_allowed_fs_type(path->dentry)) {
+       if (ovl_dentry_weird(path->dentry)) {
                pr_err("overlayfs: filesystem on '%s' not supported\n", name);
                goto out_put;
        }
@@ -752,13 +803,21 @@ static int ovl_mount_dir(const char *name, struct path *path)
        if (tmp) {
                ovl_unescape(tmp);
                err = ovl_mount_dir_noesc(tmp, path);
+
+               if (!err)
+                       if (ovl_dentry_remote(path->dentry)) {
+                               pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n",
+                                      tmp);
+                               path_put(path);
+                               err = -EINVAL;
+                       }
                kfree(tmp);
        }
        return err;
 }
 
 static int ovl_lower_dir(const char *name, struct path *path, long *namelen,
-                        int *stack_depth)
+                        int *stack_depth, bool *remote)
 {
        int err;
        struct kstatfs statfs;
@@ -775,6 +834,9 @@ static int ovl_lower_dir(const char *name, struct path *path, long *namelen,
        *namelen = max(*namelen, statfs.f_namelen);
        *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
 
+       if (ovl_dentry_remote(path->dentry))
+               *remote = true;
+
        return 0;
 
 out_put:
@@ -828,6 +890,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
        unsigned int numlower;
        unsigned int stacklen = 0;
        unsigned int i;
+       bool remote = false;
        int err;
 
        err = -ENOMEM;
@@ -901,7 +964,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
        lower = lowertmp;
        for (numlower = 0; numlower < stacklen; numlower++) {
                err = ovl_lower_dir(lower, &stack[numlower],
-                                   &ufs->lower_namelen, &sb->s_stack_depth);
+                                   &ufs->lower_namelen, &sb->s_stack_depth,
+                                   &remote);
                if (err)
                        goto out_put_lowerpath;
 
@@ -926,9 +990,10 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
                ufs->workdir = ovl_workdir_create(ufs->upper_mnt, workpath.dentry);
                err = PTR_ERR(ufs->workdir);
                if (IS_ERR(ufs->workdir)) {
-                       pr_err("overlayfs: failed to create directory %s/%s\n",
-                              ufs->config.workdir, OVL_WORKDIR_NAME);
-                       goto out_put_upper_mnt;
+                       pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n",
+                               ufs->config.workdir, OVL_WORKDIR_NAME, -err);
+                       sb->s_flags |= MS_RDONLY;
+                       ufs->workdir = NULL;
                }
        }
 
@@ -958,7 +1023,10 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
        if (!ufs->upper_mnt)
                sb->s_flags |= MS_RDONLY;
 
-       sb->s_d_op = &ovl_dentry_operations;
+       if (remote)
+               sb->s_d_op = &ovl_reval_dentry_operations;
+       else
+               sb->s_d_op = &ovl_dentry_operations;
 
        err = -ENOMEM;
        oe = ovl_alloc_entry(numlower);
@@ -998,7 +1066,6 @@ out_put_lower_mnt:
        kfree(ufs->lower_mnt);
 out_put_workdir:
        dput(ufs->workdir);
-out_put_upper_mnt:
        mntput(ufs->upper_mnt);
 out_put_lowerpath:
        for (i = 0; i < numlower; i++)