From 110289a7afbf3b4caaf802287337d1afc4b6df91 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Wed, 10 Aug 2022 21:51:09 -0700 Subject: [PATCH] mm/shmem: fix chattr fsflags support in tmpfs ext[234] have always allowed unimplemented chattr flags to be set, but other filesystems have tended to be stricter. Follow the stricter approach for tmpfs: I don't want to have to explain why csu attributes don't actually work, and we won't need to update the chattr(1) manpage; and it's never wrong to start off strict, relaxing later if persuaded. Allow only a (append only) i (immutable) A (no atime) and d (no dump). Although lsattr showed 'A' inherited, the NOATIME behavior was not being inherited: because nothing sync'ed FS_NOATIME_FL to S_NOATIME. Add shmem_set_inode_flags() to sync the flags, using inode_set_flags() to avoid that instant of lost immutablility during fileattr_set(). But that change switched generic/079 from passing to failing: because FS_IMMUTABLE_FL and FS_APPEND_FL had been unconventionally included in the INHERITED fsflags: remove them and generic/079 is back to passing. Link: https://lkml.kernel.org/r/2961dcb0-ddf3-b9f0-3268-12a4ff996856@google.com Fixes: 392005567086 ("mm/shmem: support FS_IOC_[SG]ETFLAGS in tmpfs") Signed-off-by: Hugh Dickins Cc: "Theodore Ts'o" Cc: Radoslaw Burny Cc: "Darrick J. Wong" Cc: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton --- include/linux/shmem_fs.h | 13 +++------- mm/shmem.c | 54 +++++++++++++++++++++++----------------- 2 files changed, 35 insertions(+), 32 deletions(-) diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h index 1b6c4013f691b..ff0b990de83d4 100644 --- a/include/linux/shmem_fs.h +++ b/include/linux/shmem_fs.h @@ -29,15 +29,10 @@ struct shmem_inode_info { struct inode vfs_inode; }; -#define SHMEM_FL_USER_VISIBLE FS_FL_USER_VISIBLE -#define SHMEM_FL_USER_MODIFIABLE FS_FL_USER_MODIFIABLE -#define SHMEM_FL_INHERITED FS_FL_USER_MODIFIABLE - -/* Flags that are appropriate for regular files (all but dir-specific ones). */ -#define SHMEM_REG_FLMASK (~(FS_DIRSYNC_FL | FS_TOPDIR_FL)) - -/* Flags that are appropriate for non-directories/regular files. */ -#define SHMEM_OTHER_FLMASK (FS_NODUMP_FL | FS_NOATIME_FL) +#define SHMEM_FL_USER_VISIBLE FS_FL_USER_VISIBLE +#define SHMEM_FL_USER_MODIFIABLE \ + (FS_IMMUTABLE_FL | FS_APPEND_FL | FS_NODUMP_FL | FS_NOATIME_FL) +#define SHMEM_FL_INHERITED (FS_NODUMP_FL | FS_NOATIME_FL) struct shmem_sb_info { unsigned long max_blocks; /* How many blocks are allowed */ diff --git a/mm/shmem.c b/mm/shmem.c index 5783f11351bb0..170b4078420f5 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2281,16 +2281,34 @@ static int shmem_mmap(struct file *file, struct vm_area_struct *vma) return 0; } -/* Mask out flags that are inappropriate for the given type of inode. */ -static unsigned shmem_mask_flags(umode_t mode, __u32 flags) +#ifdef CONFIG_TMPFS_XATTR +static int shmem_initxattrs(struct inode *, const struct xattr *, void *); + +/* + * chattr's fsflags are unrelated to extended attributes, + * but tmpfs has chosen to enable them under the same config option. + */ +static void shmem_set_inode_flags(struct inode *inode, unsigned int fsflags) +{ + unsigned int i_flags = 0; + + if (fsflags & FS_NOATIME_FL) + i_flags |= S_NOATIME; + if (fsflags & FS_APPEND_FL) + i_flags |= S_APPEND; + if (fsflags & FS_IMMUTABLE_FL) + i_flags |= S_IMMUTABLE; + /* + * But FS_NODUMP_FL does not require any action in i_flags. + */ + inode_set_flags(inode, i_flags, S_NOATIME | S_APPEND | S_IMMUTABLE); +} +#else +static void shmem_set_inode_flags(struct inode *inode, unsigned int fsflags) { - if (S_ISDIR(mode)) - return flags; - else if (S_ISREG(mode)) - return flags & SHMEM_REG_FLMASK; - else - return flags & SHMEM_OTHER_FLMASK; } +#define shmem_initxattrs NULL +#endif static struct inode *shmem_get_inode(struct super_block *sb, struct inode *dir, umode_t mode, dev_t dev, unsigned long flags) @@ -2319,7 +2337,8 @@ static struct inode *shmem_get_inode(struct super_block *sb, struct inode *dir, info->i_crtime = inode->i_mtime; info->fsflags = (dir == NULL) ? 0 : SHMEM_I(dir)->fsflags & SHMEM_FL_INHERITED; - info->fsflags = shmem_mask_flags(mode, info->fsflags); + if (info->fsflags) + shmem_set_inode_flags(inode, info->fsflags); INIT_LIST_HEAD(&info->shrinklist); INIT_LIST_HEAD(&info->swaplist); simple_xattrs_init(&info->xattrs); @@ -2468,12 +2487,6 @@ out_unacct_blocks: static const struct inode_operations shmem_symlink_inode_operations; static const struct inode_operations shmem_short_symlink_operations; -#ifdef CONFIG_TMPFS_XATTR -static int shmem_initxattrs(struct inode *, const struct xattr *, void *); -#else -#define shmem_initxattrs NULL -#endif - static int shmem_write_begin(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, @@ -3179,18 +3192,13 @@ static int shmem_fileattr_set(struct user_namespace *mnt_userns, if (fileattr_has_fsx(fa)) return -EOPNOTSUPP; + if (fa->flags & ~SHMEM_FL_USER_MODIFIABLE) + return -EOPNOTSUPP; info->fsflags = (info->fsflags & ~SHMEM_FL_USER_MODIFIABLE) | (fa->flags & SHMEM_FL_USER_MODIFIABLE); - inode->i_flags &= ~(S_APPEND | S_IMMUTABLE | S_NOATIME); - if (info->fsflags & FS_APPEND_FL) - inode->i_flags |= S_APPEND; - if (info->fsflags & FS_IMMUTABLE_FL) - inode->i_flags |= S_IMMUTABLE; - if (info->fsflags & FS_NOATIME_FL) - inode->i_flags |= S_NOATIME; - + shmem_set_inode_flags(inode, info->fsflags); inode->i_ctime = current_time(inode); return 0; } -- 2.39.5