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path: root/fs/overlayfs/file.c
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Diffstat (limited to 'fs/overlayfs/file.c')
-rw-r--r--fs/overlayfs/file.c170
1 files changed, 146 insertions, 24 deletions
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 0c810f20f778..0bd276e4ccbe 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -11,6 +11,7 @@
#include <linux/mount.h>
#include <linux/xattr.h>
#include <linux/uio.h>
+#include <linux/uaccess.h>
#include "overlayfs.h"
static char ovl_whatisit(struct inode *inode, struct inode *realinode)
@@ -29,10 +30,11 @@ static struct file *ovl_open_realfile(const struct file *file,
struct inode *inode = file_inode(file);
struct file *realfile;
const struct cred *old_cred;
+ int flags = file->f_flags | O_NOATIME | FMODE_NONOTIFY;
old_cred = ovl_override_creds(inode->i_sb);
- realfile = open_with_fake_path(&file->f_path, file->f_flags | O_NOATIME,
- realinode, current_cred());
+ realfile = open_with_fake_path(&file->f_path, flags, realinode,
+ current_cred());
revert_creds(old_cred);
pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n",
@@ -50,7 +52,7 @@ static int ovl_change_flags(struct file *file, unsigned int flags)
int err;
/* No atime modificaton on underlying */
- flags |= O_NOATIME;
+ flags |= O_NOATIME | FMODE_NONOTIFY;
/* If some flag changed that cannot be changed then something's amiss */
if (WARN_ON((file->f_flags ^ flags) & ~OVL_SETFL_MASK))
@@ -144,11 +146,47 @@ static int ovl_release(struct inode *inode, struct file *file)
static loff_t ovl_llseek(struct file *file, loff_t offset, int whence)
{
- struct inode *realinode = ovl_inode_real(file_inode(file));
+ struct inode *inode = file_inode(file);
+ struct fd real;
+ const struct cred *old_cred;
+ ssize_t ret;
+
+ /*
+ * The two special cases below do not need to involve real fs,
+ * so we can optimizing concurrent callers.
+ */
+ if (offset == 0) {
+ if (whence == SEEK_CUR)
+ return file->f_pos;
+
+ if (whence == SEEK_SET)
+ return vfs_setpos(file, 0, 0);
+ }
+
+ ret = ovl_real_fdget(file, &real);
+ if (ret)
+ return ret;
+
+ /*
+ * Overlay file f_pos is the master copy that is preserved
+ * through copy up and modified on read/write, but only real
+ * fs knows how to SEEK_HOLE/SEEK_DATA and real fs may impose
+ * limitations that are more strict than ->s_maxbytes for specific
+ * files, so we use the real file to perform seeks.
+ */
+ inode_lock(inode);
+ real.file->f_pos = file->f_pos;
- return generic_file_llseek_size(file, offset, whence,
- realinode->i_sb->s_maxbytes,
- i_size_read(realinode));
+ old_cred = ovl_override_creds(inode->i_sb);
+ ret = vfs_llseek(real.file, offset, whence);
+ revert_creds(old_cred);
+
+ file->f_pos = real.file->f_pos;
+ inode_unlock(inode);
+
+ fdput(real);
+
+ return ret;
}
static void ovl_file_accessed(struct file *file)
@@ -371,34 +409,118 @@ static long ovl_real_ioctl(struct file *file, unsigned int cmd,
return ret;
}
-static long ovl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+static long ovl_ioctl_set_flags(struct file *file, unsigned int cmd,
+ unsigned long arg, unsigned int iflags)
{
long ret;
struct inode *inode = file_inode(file);
+ unsigned int old_iflags;
+
+ if (!inode_owner_or_capable(inode))
+ return -EACCES;
+
+ ret = mnt_want_write_file(file);
+ if (ret)
+ return ret;
+
+ inode_lock(inode);
+
+ /* Check the capability before cred override */
+ ret = -EPERM;
+ old_iflags = READ_ONCE(inode->i_flags);
+ if (((iflags ^ old_iflags) & (S_APPEND | S_IMMUTABLE)) &&
+ !capable(CAP_LINUX_IMMUTABLE))
+ goto unlock;
+
+ ret = ovl_maybe_copy_up(file_dentry(file), O_WRONLY);
+ if (ret)
+ goto unlock;
+
+ ret = ovl_real_ioctl(file, cmd, arg);
+
+ ovl_copyflags(ovl_inode_real(inode), inode);
+unlock:
+ inode_unlock(inode);
+
+ mnt_drop_write_file(file);
+
+ return ret;
+
+}
+
+static unsigned int ovl_fsflags_to_iflags(unsigned int flags)
+{
+ unsigned int iflags = 0;
+
+ if (flags & FS_SYNC_FL)
+ iflags |= S_SYNC;
+ if (flags & FS_APPEND_FL)
+ iflags |= S_APPEND;
+ if (flags & FS_IMMUTABLE_FL)
+ iflags |= S_IMMUTABLE;
+ if (flags & FS_NOATIME_FL)
+ iflags |= S_NOATIME;
+
+ return iflags;
+}
+
+static long ovl_ioctl_set_fsflags(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ unsigned int flags;
+
+ if (get_user(flags, (int __user *) arg))
+ return -EFAULT;
+
+ return ovl_ioctl_set_flags(file, cmd, arg,
+ ovl_fsflags_to_iflags(flags));
+}
+
+static unsigned int ovl_fsxflags_to_iflags(unsigned int xflags)
+{
+ unsigned int iflags = 0;
+
+ if (xflags & FS_XFLAG_SYNC)
+ iflags |= S_SYNC;
+ if (xflags & FS_XFLAG_APPEND)
+ iflags |= S_APPEND;
+ if (xflags & FS_XFLAG_IMMUTABLE)
+ iflags |= S_IMMUTABLE;
+ if (xflags & FS_XFLAG_NOATIME)
+ iflags |= S_NOATIME;
+
+ return iflags;
+}
+
+static long ovl_ioctl_set_fsxflags(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ struct fsxattr fa;
+
+ memset(&fa, 0, sizeof(fa));
+ if (copy_from_user(&fa, (void __user *) arg, sizeof(fa)))
+ return -EFAULT;
+
+ return ovl_ioctl_set_flags(file, cmd, arg,
+ ovl_fsxflags_to_iflags(fa.fsx_xflags));
+}
+
+static long ovl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+ long ret;
switch (cmd) {
case FS_IOC_GETFLAGS:
+ case FS_IOC_FSGETXATTR:
ret = ovl_real_ioctl(file, cmd, arg);
break;
case FS_IOC_SETFLAGS:
- if (!inode_owner_or_capable(inode))
- return -EACCES;
-
- ret = mnt_want_write_file(file);
- if (ret)
- return ret;
-
- ret = ovl_maybe_copy_up(file_dentry(file), O_WRONLY);
- if (!ret) {
- ret = ovl_real_ioctl(file, cmd, arg);
-
- inode_lock(inode);
- ovl_copyflags(ovl_inode_real(inode), inode);
- inode_unlock(inode);
- }
+ ret = ovl_ioctl_set_fsflags(file, cmd, arg);
+ break;
- mnt_drop_write_file(file);
+ case FS_IOC_FSSETXATTR:
+ ret = ovl_ioctl_set_fsxflags(file, cmd, arg);
break;
default: