mm/shmem: support FS_IOC_[SG]ETFLAGS in tmpfs
This allows userspace to set flags like FS_APPEND_FL, FS_IMMUTABLE_FL, FS_NODUMP_FL, etc., like all other standard Linux file systems. [akpm@linux-foundation.org: fix CONFIG_TMPFS_XATTR=n warnings] Link: https://lkml.kernel.org/r/20220715015912.2560575-1-tytso@mit.edu Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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188043c7f4
Коммит
e408e695f5
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@ -25,9 +25,20 @@ struct shmem_inode_info {
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struct simple_xattrs xattrs; /* list of xattrs */
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struct simple_xattrs xattrs; /* list of xattrs */
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atomic_t stop_eviction; /* hold when working on inode */
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atomic_t stop_eviction; /* hold when working on inode */
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struct timespec64 i_crtime; /* file creation time */
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struct timespec64 i_crtime; /* file creation time */
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unsigned int fsflags; /* flags for FS_IOC_[SG]ETFLAGS */
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struct inode vfs_inode;
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struct inode vfs_inode;
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};
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};
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#define SHMEM_FL_USER_VISIBLE FS_FL_USER_VISIBLE
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#define SHMEM_FL_USER_MODIFIABLE FS_FL_USER_MODIFIABLE
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#define SHMEM_FL_INHERITED FS_FL_USER_MODIFIABLE
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/* Flags that are appropriate for regular files (all but dir-specific ones). */
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#define SHMEM_REG_FLMASK (~(FS_DIRSYNC_FL | FS_TOPDIR_FL))
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/* Flags that are appropriate for non-directories/regular files. */
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#define SHMEM_OTHER_FLMASK (FS_NODUMP_FL | FS_NOATIME_FL)
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struct shmem_sb_info {
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struct shmem_sb_info {
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unsigned long max_blocks; /* How many blocks are allowed */
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unsigned long max_blocks; /* How many blocks are allowed */
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struct percpu_counter used_blocks; /* How many are allocated */
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struct percpu_counter used_blocks; /* How many are allocated */
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64
mm/shmem.c
64
mm/shmem.c
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@ -28,6 +28,7 @@
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#include <linux/ramfs.h>
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#include <linux/ramfs.h>
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#include <linux/pagemap.h>
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#include <linux/pagemap.h>
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#include <linux/file.h>
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#include <linux/file.h>
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#include <linux/fileattr.h>
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#include <linux/mm.h>
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#include <linux/mm.h>
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#include <linux/random.h>
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#include <linux/random.h>
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#include <linux/sched/signal.h>
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#include <linux/sched/signal.h>
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@ -1058,6 +1059,15 @@ static int shmem_getattr(struct user_namespace *mnt_userns,
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shmem_recalc_inode(inode);
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shmem_recalc_inode(inode);
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spin_unlock_irq(&info->lock);
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spin_unlock_irq(&info->lock);
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}
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}
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if (info->fsflags & FS_APPEND_FL)
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stat->attributes |= STATX_ATTR_APPEND;
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if (info->fsflags & FS_IMMUTABLE_FL)
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stat->attributes |= STATX_ATTR_IMMUTABLE;
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if (info->fsflags & FS_NODUMP_FL)
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stat->attributes |= STATX_ATTR_NODUMP;
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stat->attributes_mask |= (STATX_ATTR_APPEND |
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STATX_ATTR_IMMUTABLE |
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STATX_ATTR_NODUMP);
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generic_fillattr(&init_user_ns, inode, stat);
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generic_fillattr(&init_user_ns, inode, stat);
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if (shmem_is_huge(NULL, inode, 0))
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if (shmem_is_huge(NULL, inode, 0))
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@ -2272,7 +2282,18 @@ static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
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return 0;
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return 0;
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}
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}
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static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
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/* Mask out flags that are inappropriate for the given type of inode. */
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static unsigned shmem_mask_flags(umode_t mode, __u32 flags)
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{
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if (S_ISDIR(mode))
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return flags;
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else if (S_ISREG(mode))
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return flags & SHMEM_REG_FLMASK;
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else
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return flags & SHMEM_OTHER_FLMASK;
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}
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static struct inode *shmem_get_inode(struct super_block *sb, struct inode *dir,
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umode_t mode, dev_t dev, unsigned long flags)
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umode_t mode, dev_t dev, unsigned long flags)
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{
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{
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struct inode *inode;
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struct inode *inode;
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@ -2297,6 +2318,9 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode
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info->seals = F_SEAL_SEAL;
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info->seals = F_SEAL_SEAL;
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info->flags = flags & VM_NORESERVE;
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info->flags = flags & VM_NORESERVE;
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info->i_crtime = inode->i_mtime;
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info->i_crtime = inode->i_mtime;
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info->fsflags = (dir == NULL) ? 0 :
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SHMEM_I(dir)->fsflags & SHMEM_FL_INHERITED;
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info->fsflags = shmem_mask_flags(mode, info->fsflags);
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INIT_LIST_HEAD(&info->shrinklist);
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INIT_LIST_HEAD(&info->shrinklist);
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INIT_LIST_HEAD(&info->swaplist);
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INIT_LIST_HEAD(&info->swaplist);
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simple_xattrs_init(&info->xattrs);
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simple_xattrs_init(&info->xattrs);
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@ -3138,6 +3162,40 @@ static const char *shmem_get_link(struct dentry *dentry,
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}
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}
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#ifdef CONFIG_TMPFS_XATTR
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#ifdef CONFIG_TMPFS_XATTR
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static int shmem_fileattr_get(struct dentry *dentry, struct fileattr *fa)
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{
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struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
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fileattr_fill_flags(fa, info->fsflags & SHMEM_FL_USER_VISIBLE);
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return 0;
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}
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static int shmem_fileattr_set(struct user_namespace *mnt_userns,
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struct dentry *dentry, struct fileattr *fa)
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{
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struct inode *inode = d_inode(dentry);
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struct shmem_inode_info *info = SHMEM_I(inode);
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if (fileattr_has_fsx(fa))
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return -EOPNOTSUPP;
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info->fsflags = (info->fsflags & ~SHMEM_FL_USER_MODIFIABLE) |
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(fa->flags & SHMEM_FL_USER_MODIFIABLE);
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inode->i_flags &= ~(S_APPEND | S_IMMUTABLE | S_NOATIME);
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if (info->fsflags & FS_APPEND_FL)
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inode->i_flags |= S_APPEND;
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if (info->fsflags & FS_IMMUTABLE_FL)
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inode->i_flags |= S_IMMUTABLE;
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if (info->fsflags & FS_NOATIME_FL)
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inode->i_flags |= S_NOATIME;
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inode->i_ctime = current_time(inode);
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return 0;
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}
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/*
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/*
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* Superblocks without xattr inode operations may get some security.* xattr
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* Superblocks without xattr inode operations may get some security.* xattr
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* support from the LSM "for free". As soon as we have any other xattrs
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* support from the LSM "for free". As soon as we have any other xattrs
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@ -3828,6 +3886,8 @@ static const struct inode_operations shmem_inode_operations = {
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#ifdef CONFIG_TMPFS_XATTR
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#ifdef CONFIG_TMPFS_XATTR
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.listxattr = shmem_listxattr,
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.listxattr = shmem_listxattr,
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.set_acl = simple_set_acl,
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.set_acl = simple_set_acl,
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.fileattr_get = shmem_fileattr_get,
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.fileattr_set = shmem_fileattr_set,
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#endif
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#endif
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};
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};
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@ -3847,6 +3907,8 @@ static const struct inode_operations shmem_dir_inode_operations = {
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#endif
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#endif
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#ifdef CONFIG_TMPFS_XATTR
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#ifdef CONFIG_TMPFS_XATTR
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.listxattr = shmem_listxattr,
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.listxattr = shmem_listxattr,
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.fileattr_get = shmem_fileattr_get,
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.fileattr_set = shmem_fileattr_set,
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#endif
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#endif
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#ifdef CONFIG_TMPFS_POSIX_ACL
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#ifdef CONFIG_TMPFS_POSIX_ACL
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.setattr = shmem_setattr,
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.setattr = shmem_setattr,
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