[v5,2/4] ima: use fs method to read integrity data

Commit Message

Mimi Zohar Aug. 10, 2017, 11:41 p.m. UTC

From: Christoph Hellwig <[e-mail]>

Add a new ->integrity_read file operation to read data for integrity
hash collection.  This is defined to be equivalent to ->read_iter,
except that it will be called with the i_rwsem held exclusively.

Signed-off-by: Christoph Hellwig <[e-mail]>
Cc: Matthew Garrett <[e-mail]>
Cc: Jan Kara <[e-mail]>
Cc: "Theodore Ts'o" <[e-mail]>
Cc: Andreas Dilger <[e-mail]>
Cc: Jaegeuk Kim <[e-mail]>
Cc: Chao Yu <[e-mail]>
Cc: Steven Whitehouse <[e-mail]>
Cc: Bob Peterson <[e-mail]>
Cc: David Woodhouse <[e-mail]>
Cc: Dave Kleikamp <[e-mail]>
Cc: Ryusuke Konishi <[e-mail]>
Cc: Mark Fasheh <[e-mail]>
Cc: Joel Becker <[e-mail]>
Cc: Richard Weinberger <[e-mail]>
Cc: "Darrick J. Wong" <[e-mail]>
Cc: Hugh Dickins <[e-mail]>
Cc: Chris Mason <[e-mail]>
Signed-off-by: Mimi Zohar <[e-mail]>

---
Changelog v5:
- removed ocf2 and gfs2 integrity_read support.
- removed ext4 special case to fail O_DIRECT open for buffered read.

Changelog v4:
- define ext2/4 specific ->integrity_read functions.
- properly fail file open with O_DIRECT on filesystem not mounted
with "-o dax".

Changelog v3:
- define simple_read_iter_from_buffer
- replace the existing efivarfs ->read method with ->read_iter method.
- squashed other fs definitions of ->integrity_read with this patch.

Changelog v2:
- change iovec to kvec

Changelog v1:
- update the patch description, removing the concept that the presence of
->integrity_read indicates that the file system can support IMA. (Mimi)

 fs/btrfs/file.c           |  1 +
 fs/efivarfs/file.c        | 12 +++++++-----
 fs/ext2/file.c            | 17 +++++++++++++++++
 fs/ext4/file.c            | 20 ++++++++++++++++++++
 fs/f2fs/file.c            |  1 +
 fs/jffs2/file.c           |  1 +
 fs/jfs/file.c             |  1 +
 fs/libfs.c                | 32 ++++++++++++++++++++++++++++++++
 fs/nilfs2/file.c          |  1 +
 fs/ramfs/file-mmu.c       |  1 +
 fs/ramfs/file-nommu.c     |  1 +
 fs/ubifs/file.c           |  1 +
 fs/xfs/xfs_file.c         | 21 +++++++++++++++++++++
 include/linux/fs.h        |  3 +++
 mm/shmem.c                |  1 +
 security/integrity/iint.c | 20 ++++++++++++++------
 16 files changed, 123 insertions(+), 11 deletions(-)

Comments

Christoph Hellwig Aug. 11, 2017, 10:21 a.m. UTC | #1

On Thu, Aug 10, 2017 at 07:41:45PM -0400, Mimi Zohar wrote:
> From: Christoph Hellwig <[e-mail]>
> 
> Add a new ->integrity_read file operation to read data for integrity
> hash collection.  This is defined to be equivalent to ->read_iter,
> except that it will be called with the i_rwsem held exclusively.
> 
> Signed-off-by: Christoph Hellwig <[e-mail]>

Btw, most of this is yours now, feel free to take over the authorship
with a little credit to me for the initial patch if you want.

> Cc: Matthew Garrett <[e-mail]>

I don't think that will reach Matthew anymore :)

> -static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
> -		size_t count, loff_t *ppos)
> +static ssize_t efivarfs_file_read_iter(struct kiocb *iocb,
> +				       struct iov_iter *iter)

The efivars switch to read_iter should be a separate patch before
this one.

>  /**
> + * simple_read_iter_from_buffer - copy data from the buffer to user space
> + * @iocb: struct containing the file, the current position and other info
> + * @to: the user space buffer to read to
> + * @from: the buffer to read from
> + * @available: the size of the buffer
> + *
> + * The simple_read_iter_from_buffer() function reads up to @available bytes
> + * from the current buffer into the user space buffer.
> + *
> + * On success, the current buffer offset is advanced by the number of bytes
> + * read, or a negative value is returned on error.
> + **/
> +ssize_t simple_read_iter_from_buffer(struct kiocb *iocb, struct iov_iter *to,
> +				     const void *from, size_t available)

The addition of simple_read_iter_from_buffer should be another separate
patch, before efivars starts using it.

Mimi Zohar Aug. 11, 2017, 1:20 p.m. UTC | #2

On Fri, 2017-08-11 at 12:21 +0200, Christoph Hellwig wrote:
> On Thu, Aug 10, 2017 at 07:41:45PM -0400, Mimi Zohar wrote:
> > From: Christoph Hellwig <[e-mail]>
> > 
> > Add a new ->integrity_read file operation to read data for integrity
> > hash collection.  This is defined to be equivalent to ->read_iter,
> > except that it will be called with the i_rwsem held exclusively.
> > 
> > Signed-off-by: Christoph Hellwig <[e-mail]>
> 
> Btw, most of this is yours now, feel free to take over the authorship
> with a little credit to me for the initial patch if you want.

Thank you so much for the initial design and patch!

> > Cc: Matthew Garrett <[e-mail]>
> 
> I don't think that will reach Matthew anymore :)

Trying his other address as listed in MAINTAINERS.

> 
> > -static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
> > -		size_t count, loff_t *ppos)
> > +static ssize_t efivarfs_file_read_iter(struct kiocb *iocb,
> > +				       struct iov_iter *iter)
> 
> The efivars switch to read_iter should be a separate patch before
> this one.

Agreed

> >  /**
> > + * simple_read_iter_from_buffer - copy data from the buffer to user space
> > + * @iocb: struct containing the file, the current position and other info
> > + * @to: the user space buffer to read to
> > + * @from: the buffer to read from
> > + * @available: the size of the buffer
> > + *
> > + * The simple_read_iter_from_buffer() function reads up to @available bytes
> > + * from the current buffer into the user space buffer.
> > + *
> > + * On success, the current buffer offset is advanced by the number of bytes
> > + * read, or a negative value is returned on error.
> > + **/
> > +ssize_t simple_read_iter_from_buffer(struct kiocb *iocb, struct iov_iter *to,
> > +				     const void *from, size_t available)
> 
> The addition of simple_read_iter_from_buffer should be another separate
> patch, before efivars starts using it.

Agreed

Mimi

Mimi Zohar Aug. 11, 2017, 5:11 p.m. UTC | #3

On Fri, 2017-08-11 at 09:20 -0400, Mimi Zohar wrote:
> On Fri, 2017-08-11 at 12:21 +0200, Christoph Hellwig wrote:
> > On Thu, Aug 10, 2017 at 07:41:45PM -0400, Mimi Zohar wrote:
> > > From: Christoph Hellwig <[e-mail]>
> > > 
> > > Add a new ->integrity_read file operation to read data for integrity
> > > hash collection.  This is defined to be equivalent to ->read_iter,
> > > except that it will be called with the i_rwsem held exclusively.
> > > 
> > > Signed-off-by: Christoph Hellwig <[e-mail]>
> > 
> > Btw, most of this is yours now, feel free to take over the authorship
> > with a little credit to me for the initial patch if you want.
> 
> Thank you so much for the initial design and patch!

After moving the libfs and efivarfs code to separate patches, the
patch hasn't changed all that much, just additional file systems.  If
you don't object, I'll leave you as the author.

Mimi

Christoph Hellwig Aug. 11, 2017, 5:15 p.m. UTC | #4

On Fri, Aug 11, 2017 at 01:11:44PM -0400, Mimi Zohar wrote:
> After moving the libfs and efivarfs code to separate patches, the
> patch hasn't changed all that much, just additional file systems.  If
> you don't object, I'll leave you as the author.

Sure - feel free to handle it whichever way you want.

Patch

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 9e75d8a39aac..2542dc66c85c 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3125,6 +3125,7 @@  const struct file_operations btrfs_file_operations = {
 #endif
 	.clone_file_range = btrfs_clone_file_range,
 	.dedupe_file_range = btrfs_dedupe_file_range,
+	.integrity_read = generic_file_read_iter,
 };
 
 void btrfs_auto_defrag_exit(void)
diff --git a/fs/efivarfs/file.c b/fs/efivarfs/file.c
index 5f22e74bbade..17955a92a5b3 100644
--- a/fs/efivarfs/file.c
+++ b/fs/efivarfs/file.c
@@ -64,9 +64,10 @@  static ssize_t efivarfs_file_write(struct file *file,
 	return bytes;
 }
 
-static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
-		size_t count, loff_t *ppos)
+static ssize_t efivarfs_file_read_iter(struct kiocb *iocb,
+				       struct iov_iter *iter)
 {
+	struct file *file = iocb->ki_filp;
 	struct efivar_entry *var = file->private_data;
 	unsigned long datasize = 0;
 	u32 attributes;
@@ -96,8 +97,8 @@  static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
 		goto out_free;
 
 	memcpy(data, &attributes, sizeof(attributes));
-	size = simple_read_from_buffer(userbuf, count, ppos,
-				       data, datasize + sizeof(attributes));
+	size = simple_read_iter_from_buffer(iocb, iter, data,
+					    datasize + sizeof(attributes));
 out_free:
 	kfree(data);
 
@@ -174,8 +175,9 @@  efivarfs_file_ioctl(struct file *file, unsigned int cmd, unsigned long p)
 
 const struct file_operations efivarfs_file_operations = {
 	.open	= simple_open,
-	.read	= efivarfs_file_read,
+	.read_iter = efivarfs_file_read_iter,
 	.write	= efivarfs_file_write,
 	.llseek	= no_llseek,
 	.unlocked_ioctl = efivarfs_file_ioctl,
+	.integrity_read	= efivarfs_file_read_iter,
 };
diff --git a/fs/ext2/file.c b/fs/ext2/file.c
index d34d32bdc944..111069de1973 100644
--- a/fs/ext2/file.c
+++ b/fs/ext2/file.c
@@ -192,6 +192,22 @@  static ssize_t ext2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 	return generic_file_read_iter(iocb, to);
 }
 
+static ssize_t ext2_file_integrity_read_iter(struct kiocb *iocb,
+					     struct iov_iter *to)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+
+	lockdep_assert_held(&inode->i_rwsem);
+#ifdef CONFIG_FS_DAX
+	if (!iov_iter_count(to))
+		return 0; /* skip atime */
+
+	if (IS_DAX(iocb->ki_filp->f_mapping->host))
+		return dax_iomap_rw(iocb, to, &ext2_iomap_ops);
+#endif
+	return generic_file_read_iter(iocb, to);
+}
+
 static ssize_t ext2_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
 #ifdef CONFIG_FS_DAX
@@ -216,6 +232,7 @@  const struct file_operations ext2_file_operations = {
 	.get_unmapped_area = thp_get_unmapped_area,
 	.splice_read	= generic_file_splice_read,
 	.splice_write	= iter_file_splice_write,
+	.integrity_read	= ext2_file_integrity_read_iter,
 };
 
 const struct inode_operations ext2_file_inode_operations = {
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 58294c9a7e1d..3ab4105c8578 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -74,6 +74,25 @@  static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 	return generic_file_read_iter(iocb, to);
 }
 
+static ssize_t ext4_file_integrity_read_iter(struct kiocb *iocb,
+					     struct iov_iter *to)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+
+	lockdep_assert_held(&inode->i_rwsem);
+	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
+		return -EIO;
+
+	if (!iov_iter_count(to))
+		return 0; /* skip atime */
+
+#ifdef CONFIG_FS_DAX
+	if (IS_DAX(inode))
+		return dax_iomap_rw(iocb, to, &ext4_iomap_ops);
+#endif
+	return generic_file_read_iter(iocb, to);
+}
+
 /*
  * Called when an inode is released. Note that this is different
  * from ext4_file_open: open gets called at every open, but release
@@ -747,6 +766,7 @@  const struct file_operations ext4_file_operations = {
 	.splice_read	= generic_file_splice_read,
 	.splice_write	= iter_file_splice_write,
 	.fallocate	= ext4_fallocate,
+	.integrity_read	= ext4_file_integrity_read_iter,
 };
 
 const struct inode_operations ext4_file_inode_operations = {
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 2706130c261b..82ea81da0b2d 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -2514,4 +2514,5 @@  const struct file_operations f2fs_file_operations = {
 #endif
 	.splice_read	= generic_file_splice_read,
 	.splice_write	= iter_file_splice_write,
+	.integrity_read	= generic_file_read_iter,
 };
diff --git a/fs/jffs2/file.c b/fs/jffs2/file.c
index c12476e309c6..5a63034cccf5 100644
--- a/fs/jffs2/file.c
+++ b/fs/jffs2/file.c
@@ -57,6 +57,7 @@  const struct file_operations jffs2_file_operations =
 	.mmap =		generic_file_readonly_mmap,
 	.fsync =	jffs2_fsync,
 	.splice_read =	generic_file_splice_read,
+	.integrity_read = generic_file_read_iter,
 };
 
 /* jffs2_file_inode_operations */
diff --git a/fs/jfs/file.c b/fs/jfs/file.c
index 739492c7a3fd..423512a810e4 100644
--- a/fs/jfs/file.c
+++ b/fs/jfs/file.c
@@ -162,4 +162,5 @@  const struct file_operations jfs_file_operations = {
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= jfs_compat_ioctl,
 #endif
+	.integrity_read	= generic_file_read_iter,
 };
diff --git a/fs/libfs.c b/fs/libfs.c
index 3aabe553fc45..b6e304c6828b 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -16,6 +16,7 @@ 
 #include <linux/exportfs.h>
 #include <linux/writeback.h>
 #include <linux/buffer_head.h> /* sync_mapping_buffers */
+#include <linux/uio.h>
 
 #include <linux/uaccess.h>
 
@@ -676,6 +677,37 @@  ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
 EXPORT_SYMBOL(simple_write_to_buffer);
 
 /**
+ * simple_read_iter_from_buffer - copy data from the buffer to user space
+ * @iocb: struct containing the file, the current position and other info
+ * @to: the user space buffer to read to
+ * @from: the buffer to read from
+ * @available: the size of the buffer
+ *
+ * The simple_read_iter_from_buffer() function reads up to @available bytes
+ * from the current buffer into the user space buffer.
+ *
+ * On success, the current buffer offset is advanced by the number of bytes
+ * read, or a negative value is returned on error.
+ **/
+ssize_t simple_read_iter_from_buffer(struct kiocb *iocb, struct iov_iter *to,
+				     const void *from, size_t available)
+{
+	loff_t pos = iocb->ki_pos;
+	size_t ret;
+
+	if (pos < 0)
+		return -EINVAL;
+	if (pos >= available)
+		return 0;
+	ret = copy_to_iter(from + pos, available - pos, to);
+	if (!ret && iov_iter_count(to))
+		return -EFAULT;
+	iocb->ki_pos = pos + ret;
+	return ret;
+}
+EXPORT_SYMBOL(simple_read_iter_from_buffer);
+
+/**
  * memory_read_from_buffer - copy data from the buffer
  * @to: the kernel space buffer to read to
  * @count: the maximum number of bytes to read
diff --git a/fs/nilfs2/file.c b/fs/nilfs2/file.c
index c5fa3dee72fc..55e058ac487f 100644
--- a/fs/nilfs2/file.c
+++ b/fs/nilfs2/file.c
@@ -150,6 +150,7 @@  const struct file_operations nilfs_file_operations = {
 	/* .release	= nilfs_release_file, */
 	.fsync		= nilfs_sync_file,
 	.splice_read	= generic_file_splice_read,
+	.integrity_read	= generic_file_read_iter,
 };
 
 const struct inode_operations nilfs_file_inode_operations = {
diff --git a/fs/ramfs/file-mmu.c b/fs/ramfs/file-mmu.c
index 12af0490322f..4f24d1b589b1 100644
--- a/fs/ramfs/file-mmu.c
+++ b/fs/ramfs/file-mmu.c
@@ -47,6 +47,7 @@  const struct file_operations ramfs_file_operations = {
 	.splice_write	= iter_file_splice_write,
 	.llseek		= generic_file_llseek,
 	.get_unmapped_area	= ramfs_mmu_get_unmapped_area,
+	.integrity_read	= generic_file_read_iter,
 };
 
 const struct inode_operations ramfs_file_inode_operations = {
diff --git a/fs/ramfs/file-nommu.c b/fs/ramfs/file-nommu.c
index 2ef7ce75c062..5ee704fa84e0 100644
--- a/fs/ramfs/file-nommu.c
+++ b/fs/ramfs/file-nommu.c
@@ -50,6 +50,7 @@  const struct file_operations ramfs_file_operations = {
 	.splice_read		= generic_file_splice_read,
 	.splice_write		= iter_file_splice_write,
 	.llseek			= generic_file_llseek,
+	.integrity_read		= generic_file_read_iter,
 };
 
 const struct inode_operations ramfs_file_inode_operations = {
diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index 8cad0b19b404..5e52a315e18b 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -1747,4 +1747,5 @@  const struct file_operations ubifs_file_operations = {
 #ifdef CONFIG_COMPAT
 	.compat_ioctl   = ubifs_compat_ioctl,
 #endif
+	.integrity_read = generic_file_read_iter,
 };
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index c4893e226fd8..0a6704b563d6 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -292,6 +292,26 @@  xfs_file_read_iter(
 	return ret;
 }
 
+static ssize_t
+xfs_integrity_read(
+	struct kiocb		*iocb,
+	struct iov_iter		*to)
+{
+	struct inode		*inode = file_inode(iocb->ki_filp);
+	struct xfs_mount	*mp = XFS_I(inode)->i_mount;
+
+	lockdep_assert_held(&inode->i_rwsem);
+
+	XFS_STATS_INC(mp, xs_read_calls);
+
+	if (XFS_FORCED_SHUTDOWN(mp))
+		return -EIO;
+
+	if (IS_DAX(inode))
+		return dax_iomap_rw(iocb, to, &xfs_iomap_ops);
+	return generic_file_read_iter(iocb, to);
+}
+
 /*
  * Zero any on disk space between the current EOF and the new, larger EOF.
  *
@@ -1175,6 +1195,7 @@  const struct file_operations xfs_file_operations = {
 	.fallocate	= xfs_file_fallocate,
 	.clone_file_range = xfs_file_clone_range,
 	.dedupe_file_range = xfs_file_dedupe_range,
+	.integrity_read	= xfs_integrity_read,
 };
 
 const struct file_operations xfs_dir_file_operations = {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 6e1fd5d21248..8d0d10e1dd93 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1699,6 +1699,7 @@  struct file_operations {
 			u64);
 	ssize_t (*dedupe_file_range)(struct file *, u64, u64, struct file *,
 			u64);
+	ssize_t (*integrity_read)(struct kiocb *, struct iov_iter *);
 } __randomize_layout;
 
 struct inode_operations {
@@ -3097,6 +3098,8 @@  extern void simple_release_fs(struct vfsmount **mount, int *count);
 
 extern ssize_t simple_read_from_buffer(void __user *to, size_t count,
 			loff_t *ppos, const void *from, size_t available);
+extern ssize_t simple_read_iter_from_buffer(struct kiocb *iocb,
+		struct iov_iter *to, const void *from, size_t available);
 extern ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
 		const void __user *from, size_t count);
 
diff --git a/mm/shmem.c b/mm/shmem.c
index b0aa6075d164..805d99011ca4 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -3849,6 +3849,7 @@  static const struct file_operations shmem_file_operations = {
 	.splice_read	= generic_file_splice_read,
 	.splice_write	= iter_file_splice_write,
 	.fallocate	= shmem_fallocate,
+	.integrity_read	= shmem_file_read_iter,
 #endif
 };
 
diff --git a/security/integrity/iint.c b/security/integrity/iint.c
index 6fc888ca468e..df04f35a1d40 100644
--- a/security/integrity/iint.c
+++ b/security/integrity/iint.c
@@ -21,6 +21,7 @@ 
 #include <linux/rbtree.h>
 #include <linux/file.h>
 #include <linux/uaccess.h>
+#include <linux/uio.h>
 #include "integrity.h"
 
 static struct rb_root integrity_iint_tree = RB_ROOT;
@@ -184,18 +185,25 @@  security_initcall(integrity_iintcache_init);
 int integrity_kernel_read(struct file *file, loff_t offset,
 			  void *addr, unsigned long count)
 {
-	mm_segment_t old_fs;
-	char __user *buf = (char __user *)addr;
+	struct inode *inode = file_inode(file);
+	struct kvec iov = { .iov_base = addr, .iov_len = count };
+	struct kiocb kiocb;
+	struct iov_iter iter;
 	ssize_t ret;
 
+	lockdep_assert_held(&inode->i_rwsem);
+
 	if (!(file->f_mode & FMODE_READ))
 		return -EBADF;
+	if (!file->f_op->integrity_read)
+		return -EBADF;
 
-	old_fs = get_fs();
-	set_fs(get_ds());
-	ret = __vfs_read(file, buf, count, &offset);
-	set_fs(old_fs);
+	init_sync_kiocb(&kiocb, file);
+	kiocb.ki_pos = offset;
+	iov_iter_kvec(&iter, READ | ITER_KVEC, &iov, 1, count);
 
+	ret = file->f_op->integrity_read(&kiocb, &iter);
+	BUG_ON(ret == -EIOCBQUEUED);
 	return ret;
 }