From 4c5b479975212065ef39786e115fde42847e95a9 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Wed, 7 Apr 2021 14:36:42 +0200 Subject: vfs: add fileattr ops There's a substantial amount of boilerplate in filesystems handling FS_IOC_[GS]ETFLAGS/ FS_IOC_FS[GS]ETXATTR ioctls. Also due to userspace buffers being involved in the ioctl API this is difficult to stack, as shown by overlayfs issues related to these ioctls. Introduce a new internal API named "fileattr" (fsxattr can be confused with xattr, xflags is inappropriate, since this is more than just flags). There's significant overlap between flags and xflags and this API handles the conversions automatically, so filesystems may choose which one to use. In ->fileattr_get() a hint is provided to the filesystem whether flags or xattr are being requested by userspace, but in this series this hint is ignored by all filesystems, since generating all the attributes is cheap. If a filesystem doesn't implemement the fileattr API, just fall back to f_op->ioctl(). When all filesystems are converted, the fallback can be removed. 32bit compat ioctls are now handled by the generic code as well. Signed-off-by: Miklos Szeredi --- include/linux/fileattr.h | 59 ++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/fs.h | 4 ++++ 2 files changed, 63 insertions(+) create mode 100644 include/linux/fileattr.h (limited to 'include/linux') diff --git a/include/linux/fileattr.h b/include/linux/fileattr.h new file mode 100644 index 000000000000..9e37e063ac69 --- /dev/null +++ b/include/linux/fileattr.h @@ -0,0 +1,59 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef _LINUX_FILEATTR_H +#define _LINUX_FILEATTR_H + +/* Flags shared betwen flags/xflags */ +#define FS_COMMON_FL \ + (FS_SYNC_FL | FS_IMMUTABLE_FL | FS_APPEND_FL | \ + FS_NODUMP_FL | FS_NOATIME_FL | FS_DAX_FL | \ + FS_PROJINHERIT_FL) + +#define FS_XFLAG_COMMON \ + (FS_XFLAG_SYNC | FS_XFLAG_IMMUTABLE | FS_XFLAG_APPEND | \ + FS_XFLAG_NODUMP | FS_XFLAG_NOATIME | FS_XFLAG_DAX | \ + FS_XFLAG_PROJINHERIT) + +/* + * Merged interface for miscellaneous file attributes. 'flags' originates from + * ext* and 'fsx_flags' from xfs. There's some overlap between the two, which + * is handled by the VFS helpers, so filesystems are free to implement just one + * or both of these sub-interfaces. + */ +struct fileattr { + u32 flags; /* flags (FS_IOC_GETFLAGS/FS_IOC_SETFLAGS) */ + /* struct fsxattr: */ + u32 fsx_xflags; /* xflags field value (get/set) */ + u32 fsx_extsize; /* extsize field value (get/set)*/ + u32 fsx_nextents; /* nextents field value (get) */ + u32 fsx_projid; /* project identifier (get/set) */ + u32 fsx_cowextsize; /* CoW extsize field value (get/set)*/ + /* selectors: */ + bool flags_valid:1; + bool fsx_valid:1; +}; + +int copy_fsxattr_to_user(const struct fileattr *fa, struct fsxattr __user *ufa); + +void fileattr_fill_xflags(struct fileattr *fa, u32 xflags); +void fileattr_fill_flags(struct fileattr *fa, u32 flags); + +/** + * fileattr_has_fsx - check for extended flags/attributes + * @fa: fileattr pointer + * + * Return: true if any attributes are present that are not represented in + * ->flags. + */ +static inline bool fileattr_has_fsx(const struct fileattr *fa) +{ + return fa->fsx_valid && + ((fa->fsx_xflags & ~FS_XFLAG_COMMON) || fa->fsx_extsize != 0 || + fa->fsx_projid != 0 || fa->fsx_cowextsize != 0); +} + +int vfs_fileattr_get(struct dentry *dentry, struct fileattr *fa); +int vfs_fileattr_set(struct user_namespace *mnt_userns, struct dentry *dentry, + struct fileattr *fa); + +#endif /* _LINUX_FILEATTR_H */ diff --git a/include/linux/fs.h b/include/linux/fs.h index ec8f3ddf4a6a..156b78f42a28 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -70,6 +70,7 @@ struct fsverity_info; struct fsverity_operations; struct fs_context; struct fs_parameter_spec; +struct fileattr; extern void __init inode_init(void); extern void __init inode_init_early(void); @@ -1963,6 +1964,9 @@ struct inode_operations { struct dentry *, umode_t); int (*set_acl)(struct user_namespace *, struct inode *, struct posix_acl *, int); + int (*fileattr_set)(struct user_namespace *mnt_userns, + struct dentry *dentry, struct fileattr *fa); + int (*fileattr_get)(struct dentry *dentry, struct fileattr *fa); } ____cacheline_aligned; static inline ssize_t call_read_iter(struct file *file, struct kiocb *kio, -- cgit v1.2.3 From 51db776a430edd7477a779be0dc5c6fef4a05884 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Wed, 7 Apr 2021 14:36:44 +0200 Subject: vfs: remove unused ioctl helpers Remove vfs_ioc_setflags_prepare(), vfs_ioc_fssetxattr_check() and simple_fill_fsxattr(), which are no longer used. Signed-off-by: Miklos Szeredi Reviewed-by: Darrick J. Wong --- fs/inode.c | 87 ------------------------------------------------------ include/linux/fs.h | 12 -------- 2 files changed, 99 deletions(-) (limited to 'include/linux') diff --git a/fs/inode.c b/fs/inode.c index a047ab306f9a..ae526fd9c0a4 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -12,7 +12,6 @@ #include #include #include -#include #include #include #include @@ -2314,89 +2313,3 @@ struct timespec64 current_time(struct inode *inode) return timestamp_truncate(now, inode); } EXPORT_SYMBOL(current_time); - -/* - * Generic function to check FS_IOC_SETFLAGS values and reject any invalid - * configurations. - * - * Note: the caller should be holding i_mutex, or else be sure that they have - * exclusive access to the inode structure. - */ -int vfs_ioc_setflags_prepare(struct inode *inode, unsigned int oldflags, - unsigned int flags) -{ - /* - * The IMMUTABLE and APPEND_ONLY flags can only be changed by - * the relevant capability. - * - * This test looks nicer. Thanks to Pauline Middelink - */ - if ((flags ^ oldflags) & (FS_APPEND_FL | FS_IMMUTABLE_FL) && - !capable(CAP_LINUX_IMMUTABLE)) - return -EPERM; - - return fscrypt_prepare_setflags(inode, oldflags, flags); -} -EXPORT_SYMBOL(vfs_ioc_setflags_prepare); - -/* - * Generic function to check FS_IOC_FSSETXATTR values and reject any invalid - * configurations. - * - * Note: the caller should be holding i_mutex, or else be sure that they have - * exclusive access to the inode structure. - */ -int vfs_ioc_fssetxattr_check(struct inode *inode, const struct fsxattr *old_fa, - struct fsxattr *fa) -{ - /* - * Can't modify an immutable/append-only file unless we have - * appropriate permission. - */ - if ((old_fa->fsx_xflags ^ fa->fsx_xflags) & - (FS_XFLAG_IMMUTABLE | FS_XFLAG_APPEND) && - !capable(CAP_LINUX_IMMUTABLE)) - return -EPERM; - - /* - * Project Quota ID state is only allowed to change from within the init - * namespace. Enforce that restriction only if we are trying to change - * the quota ID state. Everything else is allowed in user namespaces. - */ - if (current_user_ns() != &init_user_ns) { - if (old_fa->fsx_projid != fa->fsx_projid) - return -EINVAL; - if ((old_fa->fsx_xflags ^ fa->fsx_xflags) & - FS_XFLAG_PROJINHERIT) - return -EINVAL; - } - - /* Check extent size hints. */ - if ((fa->fsx_xflags & FS_XFLAG_EXTSIZE) && !S_ISREG(inode->i_mode)) - return -EINVAL; - - if ((fa->fsx_xflags & FS_XFLAG_EXTSZINHERIT) && - !S_ISDIR(inode->i_mode)) - return -EINVAL; - - if ((fa->fsx_xflags & FS_XFLAG_COWEXTSIZE) && - !S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode)) - return -EINVAL; - - /* - * It is only valid to set the DAX flag on regular files and - * directories on filesystems. - */ - if ((fa->fsx_xflags & FS_XFLAG_DAX) && - !(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))) - return -EINVAL; - - /* Extent size hints of zero turn off the flags. */ - if (fa->fsx_extsize == 0) - fa->fsx_xflags &= ~(FS_XFLAG_EXTSIZE | FS_XFLAG_EXTSZINHERIT); - if (fa->fsx_cowextsize == 0) - fa->fsx_xflags &= ~FS_XFLAG_COWEXTSIZE; - - return 0; -} -EXPORT_SYMBOL(vfs_ioc_fssetxattr_check); diff --git a/include/linux/fs.h b/include/linux/fs.h index 156b78f42a28..820fdc62ac30 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3571,18 +3571,6 @@ extern int vfs_fadvise(struct file *file, loff_t offset, loff_t len, extern int generic_fadvise(struct file *file, loff_t offset, loff_t len, int advice); -int vfs_ioc_setflags_prepare(struct inode *inode, unsigned int oldflags, - unsigned int flags); - -int vfs_ioc_fssetxattr_check(struct inode *inode, const struct fsxattr *old_fa, - struct fsxattr *fa); - -static inline void simple_fill_fsxattr(struct fsxattr *fa, __u32 xflags) -{ - memset(fa, 0, sizeof(*fa)); - fa->fsx_xflags = xflags; -} - /* * Flush file data before changing attributes. Caller must hold any locks * required to prevent further writes to this file until we're done setting -- cgit v1.2.3