From: Linus Torvalds Date: Thu, 21 Jan 2016 20:20:46 +0000 (-0800) Subject: Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszer... X-Git-Tag: v4.5-rc1~31 X-Git-Url: http://git.cascardo.info/?p=cascardo%2Flinux.git;a=commitdiff_plain;h=e9f57ebcba563e0cd532926cab83c92bb4d79360;hp=5c89e9ea7ef1feaa147325b2ab47a89a147fb903 Merge branch 'overlayfs-linus' of git://git./linux/kernel/git/mszeredi/vfs Pull overlayfs updates from Miklos Szeredi: "This contains several bug fixes and a new mount option 'default_permissions' that allows read-only exported NFS filesystems to be used as lower layer" * 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: ovl: check dentry positiveness in ovl_cleanup_whiteouts() ovl: setattr: check permissions before copy-up ovl: root: copy attr ovl: move super block magic number to magic.h ovl: use a minimal buffer in ovl_copy_xattr ovl: allow zero size xattr ovl: default permissions --- diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index 0a8983492d91..eff6319d5037 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -22,9 +22,9 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new) { - ssize_t list_size, size; - char *buf, *name, *value; - int error; + ssize_t list_size, size, value_size = 0; + char *buf, *name, *value = NULL; + int uninitialized_var(error); if (!old->d_inode->i_op->getxattr || !new->d_inode->i_op->getxattr) @@ -41,29 +41,40 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new) if (!buf) return -ENOMEM; - error = -ENOMEM; - value = kmalloc(XATTR_SIZE_MAX, GFP_KERNEL); - if (!value) - goto out; - list_size = vfs_listxattr(old, buf, list_size); if (list_size <= 0) { error = list_size; - goto out_free_value; + goto out; } for (name = buf; name < (buf + list_size); name += strlen(name) + 1) { - size = vfs_getxattr(old, name, value, XATTR_SIZE_MAX); - if (size <= 0) { +retry: + size = vfs_getxattr(old, name, value, value_size); + if (size == -ERANGE) + size = vfs_getxattr(old, name, NULL, 0); + + if (size < 0) { error = size; - goto out_free_value; + break; + } + + if (size > value_size) { + void *new; + + new = krealloc(value, size, GFP_KERNEL); + if (!new) { + error = -ENOMEM; + break; + } + value = new; + value_size = size; + goto retry; } + error = vfs_setxattr(new, name, value, size, 0); if (error) - goto out_free_value; + break; } - -out_free_value: kfree(value); out: kfree(buf); diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index 964a60fa7afc..bf996e574f3d 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -42,6 +42,19 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr) int err; struct dentry *upperdentry; + /* + * Check for permissions before trying to copy-up. This is redundant + * since it will be rechecked later by ->setattr() on upper dentry. But + * without this, copy-up can be triggered by just about anybody. + * + * We don't initialize inode->size, which just means that + * inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not + * check for a swapfile (which this won't be anyway). + */ + err = inode_change_ok(dentry->d_inode, attr); + if (err) + return err; + err = ovl_want_write(dentry); if (err) goto out; @@ -95,6 +108,29 @@ 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 e17154aeaae4..99b4168c36ff 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/readdir.c b/fs/overlayfs/readdir.c index 70e9af551600..adcb1398c481 100644 --- a/fs/overlayfs/readdir.c +++ b/fs/overlayfs/readdir.c @@ -571,7 +571,8 @@ void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list) (int) PTR_ERR(dentry)); continue; } - ovl_cleanup(upper->d_inode, dentry); + if (dentry->d_inode) + ovl_cleanup(upper->d_inode, dentry); dput(dentry); } mutex_unlock(&upper->d_inode->i_mutex); diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index e38ee0fed24a..a4cbdf9824c7 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -9,6 +9,7 @@ #include #include +#include #include #include #include @@ -24,12 +25,11 @@ MODULE_AUTHOR("Miklos Szeredi "); MODULE_DESCRIPTION("Overlay filesystem"); MODULE_LICENSE("GPL"); -#define OVERLAYFS_SUPER_MAGIC 0x794c7630 - struct ovl_config { char *lowerdir; char *upperdir; char *workdir; + bool default_permissions; }; /* private information held for overlayfs's superblock */ @@ -154,6 +154,18 @@ 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 +173,13 @@ 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 +613,8 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) seq_show_option(m, "upperdir", ufs->config.upperdir); seq_show_option(m, "workdir", ufs->config.workdir); } + if (ufs->config.default_permissions) + seq_puts(m, ",default_permissions"); return 0; } @@ -618,6 +639,7 @@ enum { OPT_LOWERDIR, OPT_UPPERDIR, OPT_WORKDIR, + OPT_DEFAULT_PERMISSIONS, OPT_ERR, }; @@ -625,6 +647,7 @@ 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 +708,10 @@ 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; @@ -910,6 +937,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) } sb->s_stack_depth = 0; + sb->s_maxbytes = MAX_LFS_FILESIZE; if (ufs->config.upperdir) { if (!ufs->config.workdir) { pr_err("overlayfs: missing 'workdir'\n"); @@ -1053,6 +1081,9 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) root_dentry->d_fsdata = oe; + ovl_copyattr(ovl_dentry_real(root_dentry)->d_inode, + root_dentry->d_inode); + sb->s_magic = OVERLAYFS_SUPER_MAGIC; sb->s_op = &ovl_super_operations; sb->s_root = root_dentry; diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h index b283d56c1db9..0de181ad73d5 100644 --- a/include/uapi/linux/magic.h +++ b/include/uapi/linux/magic.h @@ -31,6 +31,7 @@ #define PSTOREFS_MAGIC 0x6165676C #define EFIVARFS_MAGIC 0xde5e81e4 #define HOSTFS_SUPER_MAGIC 0x00c0ffee +#define OVERLAYFS_SUPER_MAGIC 0x794c7630 #define MINIX_SUPER_MAGIC 0x137F /* minix v1 fs, 14 char names */ #define MINIX_SUPER_MAGIC2 0x138F /* minix v1 fs, 30 char names */