diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index ec0c2a050043..76546314e35f 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -98,6 +98,29 @@ int ovl_permission(struct inode *inode, int mask) realdentry = ovl_entry_real(oe, &is_upper); + if (ovl_is_default_permissions(inode)) { + struct kstat stat; + struct path realpath = { .dentry = realdentry }; + + if (mask & MAY_NOT_BLOCK) + return -ECHILD; + + realpath.mnt = ovl_entry_mnt_real(oe, inode, is_upper); + + err = vfs_getattr(&realpath, &stat); + if (err) + return err; + + if ((stat.mode ^ inode->i_mode) & S_IFMT) + return -ESTALE; + + inode->i_mode = stat.mode; + inode->i_uid = stat.uid; + inode->i_gid = stat.gid; + + return generic_permission(inode, mask); + } + /* Careful in RCU walk mode */ realinode = ACCESS_ONCE(realdentry->d_inode); if (!realinode) { diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index ea5a40b06e3a..f3e6efefe40b 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -142,7 +142,10 @@ struct dentry *ovl_dentry_upper(struct dentry *dentry); struct dentry *ovl_dentry_lower(struct dentry *dentry); struct dentry *ovl_dentry_real(struct dentry *dentry); struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper); +struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode, + bool is_upper); struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry); +bool ovl_is_default_permissions(struct inode *inode); void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache); struct dentry *ovl_workdir(struct dentry *dentry); int ovl_want_write(struct dentry *dentry); diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 8d04b86e0680..97cacb525974 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -30,6 +30,7 @@ struct ovl_config { char *lowerdir; char *upperdir; char *workdir; + bool default_permissions; }; /* private information held for overlayfs's superblock */ @@ -154,6 +155,18 @@ struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper) return realdentry; } +struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode, + bool is_upper) +{ + if (is_upper) { + struct ovl_fs *ofs = inode->i_sb->s_fs_info; + + return ofs->upper_mnt; + } else { + return oe->numlower ? oe->lowerstack[0].mnt : NULL; + } +} + struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry) { struct ovl_entry *oe = dentry->d_fsdata; @@ -161,6 +174,13 @@ struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry) return oe->cache; } +bool ovl_is_default_permissions(struct inode *inode) +{ + struct ovl_fs *ofs = inode->i_sb->s_fs_info; + + return ofs->config.default_permissions; +} + void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache) { struct ovl_entry *oe = dentry->d_fsdata; @@ -594,6 +614,8 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) seq_printf(m, ",upperdir=%s", ufs->config.upperdir); seq_printf(m, ",workdir=%s", ufs->config.workdir); } + if (ufs->config.default_permissions) + seq_puts(m, ",default_permissions"); return 0; } @@ -618,6 +640,7 @@ enum { OPT_LOWERDIR, OPT_UPPERDIR, OPT_WORKDIR, + OPT_DEFAULT_PERMISSIONS, OPT_ERR, }; @@ -625,6 +648,7 @@ static const match_table_t ovl_tokens = { {OPT_LOWERDIR, "lowerdir=%s"}, {OPT_UPPERDIR, "upperdir=%s"}, {OPT_WORKDIR, "workdir=%s"}, + {OPT_DEFAULT_PERMISSIONS, "default_permissions"}, {OPT_ERR, NULL} }; @@ -685,6 +709,10 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) return -ENOMEM; break; + case OPT_DEFAULT_PERMISSIONS: + config->default_permissions = true; + break; + default: pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p); return -EINVAL;