From: Amir Goldstein <amir73il@xxxxxxxxx> We intend to add support for more xflags to selective filesystems and We cannot rely on copy_struct_from_user() to detect this extension. In preparation of extending the API, do not allow setting xflags unknown by this kernel version. Also do not pass the read-only flags and read-only field fsx_nextents to filesystem. These changes should not affect existing chattr programs that use the ioctl to get fsxattr before setting the new values. Link: https://lore.kernel.org/linux-fsdevel/20250216164029.20673-4-pali@xxxxxxxxxx/ Cc: Pali Rohár <pali@xxxxxxxxxx> Cc: Andrey Albershteyn <aalbersh@xxxxxxxxxx> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx> Signed-off-by: Andrey Albershteyn <aalbersh@xxxxxxxxxx> --- fs/file_attr.c | 8 +++++++- include/linux/fileattr.h | 20 ++++++++++++++++++++ 2 files changed, 27 insertions(+), 1 deletion(-) diff --git a/fs/file_attr.c b/fs/file_attr.c index 4e85fa00c092..62f08872d4ad 100644 --- a/fs/file_attr.c +++ b/fs/file_attr.c @@ -99,9 +99,10 @@ EXPORT_SYMBOL(vfs_fileattr_get); int copy_fsxattr_to_user(const struct fileattr *fa, struct fsxattr __user *ufa) { struct fsxattr xfa; + __u32 mask = FS_XFLAGS_MASK; memset(&xfa, 0, sizeof(xfa)); - xfa.fsx_xflags = fa->fsx_xflags; + xfa.fsx_xflags = fa->fsx_xflags & mask; xfa.fsx_extsize = fa->fsx_extsize; xfa.fsx_nextents = fa->fsx_nextents; xfa.fsx_projid = fa->fsx_projid; @@ -118,11 +119,16 @@ static int copy_fsxattr_from_user(struct fileattr *fa, struct fsxattr __user *ufa) { struct fsxattr xfa; + __u32 mask = FS_XFLAGS_MASK; if (copy_from_user(&xfa, ufa, sizeof(xfa))) return -EFAULT; + if (xfa.fsx_xflags & ~mask) + return -EINVAL; + fileattr_fill_xflags(fa, xfa.fsx_xflags); + fa->fsx_xflags &= ~FS_XFLAG_RDONLY_MASK; fa->fsx_extsize = xfa.fsx_extsize; fa->fsx_nextents = xfa.fsx_nextents; fa->fsx_projid = xfa.fsx_projid; diff --git a/include/linux/fileattr.h b/include/linux/fileattr.h index 6030d0bf7ad3..e2a2f4ae242d 100644 --- a/include/linux/fileattr.h +++ b/include/linux/fileattr.h @@ -14,6 +14,26 @@ FS_XFLAG_NODUMP | FS_XFLAG_NOATIME | FS_XFLAG_DAX | \ FS_XFLAG_PROJINHERIT) +/* Read-only inode flags */ +#define FS_XFLAG_RDONLY_MASK \ + (FS_XFLAG_PREALLOC | FS_XFLAG_HASATTR) + +/* Flags to indicate valid value of fsx_ fields */ +#define FS_XFLAG_VALUES_MASK \ + (FS_XFLAG_EXTSIZE | FS_XFLAG_COWEXTSIZE) + +/* Flags for directories */ +#define FS_XFLAG_DIRONLY_MASK \ + (FS_XFLAG_RTINHERIT | FS_XFLAG_NOSYMLINKS | FS_XFLAG_EXTSZINHERIT) + +/* Misc settable flags */ +#define FS_XFLAG_MISC_MASK \ + (FS_XFLAG_REALTIME | FS_XFLAG_NODEFRAG | FS_XFLAG_FILESTREAM) + +#define FS_XFLAGS_MASK \ + (FS_XFLAG_COMMON | FS_XFLAG_RDONLY_MASK | FS_XFLAG_VALUES_MASK | \ + FS_XFLAG_DIRONLY_MASK | FS_XFLAG_MISC_MASK) + /* * Merged interface for miscellaneous file attributes. 'flags' originates from * ext* and 'fsx_flags' from xfs. There's some overlap between the two, which -- 2.47.2
