lkml.org 
[lkml]   [2017]   [Sep]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 3/3] ima: use fs method to read integrity data
From
Date
On Fri, 2017-09-15 at 05:04 -0400, Mimi Zohar wrote:
> On Thu, 2017-09-14 at 22:50 -0700, Linus Torvalds wrote:
> > This is still wrong.
> >
> > (a) there is no explanation for why we need that exclusive lock in the
> > first place
>
> > Why should a read need exclusive access? You'd think shared is sufficient.
>
> True, reading a file shouldn't require an exclusive lock.  The
> exclusive lock is taken to prevent the file from changing while the
> file hash is being calculated.

And also to prevent the file hash from being calculated multiple
times.

>
> > But regardless, it needs *explanation*.
>
> Agreed.  A fuller explanation was included in the cover letter that
> should have also been included in the patch description.  The
> following is taken from the cover letter:
>
> With the introduction of IMA-appraisal and the need to write file
> hashes as security xattrs, IMA needed to take the global i_mutex
> lock.  process_measurement() took the iint->mutex first and then
> the i_mutex, while setxattr, chmod and chown took the locks in
> reverse order.  To resolve this potential deadlock, the iint->mutex
> was removed.
>
> Some filesystems have recently replaced their filesystem dependent
> lock with the global i_rwsem (formerly the i_mutex) to read a file.
> As a result, when IMA attempts to calculate the file hash, reading
> the file attempts to take the i_rwsem again.
>
> To resolve this locking problem, this patch set defines a new
> ->integrity_read file operation method.
>
> (Fixes: Commit 6552321831dc "xfs: remove i_iolock and use i_rwsem in
> the VFS inode instead")
>
> Mimi
>
> > (b) the lockdep test isn't for the exclusive lock that the code comment
> > says it is
> >
> > So no, this needs more work.
> > 
> >     Linus
> > 
>
> >
> > On Sep 14, 2017 21:59, "Mimi Zohar" <zohar@linux.vnet.ibm.com> wrote:
> >
> > > From: Christoph Hellwig <hch@lst.de>
> > >
> > > 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.
> > >
> > > (Based on Christoph's original patch.)
> > >
> > > Signed-off-by: Christoph Hellwig <hch@lst.de>
> > > Cc: Matthew Garrett <mjg59@srcf.ucam.org>
> > > Cc: Jan Kara <jack@suse.com>
> > > Cc: "Theodore Ts'o" <tytso@mit.edu>
> > > Cc: Andreas Dilger <adilger.kernel@dilger.ca>
> > > Cc: Jaegeuk Kim <jaegeuk@kernel.org>
> > > Cc: Chao Yu <yuchao0@huawei.com>
> > > Cc: Steven Whitehouse <swhiteho@redhat.com>
> > > Cc: Bob Peterson <rpeterso@redhat.com>
> > > Cc: David Woodhouse <dwmw2@infradead.org>
> > > Cc: Dave Kleikamp <shaggy@kernel.org>
> > > Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
> > > Cc: Mark Fasheh <mfasheh@versity.com>
> > > Cc: Joel Becker <jlbec@evilplan.org>
> > > Cc: Richard Weinberger <richard@nod.at>
> > > Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
> > > Cc: Hugh Dickins <hughd@google.com>
> > > Cc: Chris Mason <clm@fb.com>
> > > Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
> > > Reviewed-by: Jan Kara <jack@suse.cz>
> > > Reviewed-by: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
> > > ---
> > > fs/btrfs/file.c | 1 +
> > > fs/efivarfs/file.c | 1 +
> > > 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/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 | 1 +
> > > mm/shmem.c | 1 +
> > > security/integrity/iint.c | 20 ++++++++++++++------
> > > 15 files changed, 83 insertions(+), 6 deletions(-)
> > >
> > > 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 863f1b100165..17955a92a5b3 100644
> > > --- a/fs/efivarfs/file.c
> > > +++ b/fs/efivarfs/file.c
> > > @@ -179,4 +179,5 @@ const struct file_operations efivarfs_file_operations
> > > = {
> > > .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/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 e522d25d0836..f6a01d3efce5 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 {
> > > 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 c84e05866052..c3a07276f745 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;
> > > }
> > >
> > > --
> > > 2.7.4
> > >
> > >
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-security-module" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>

\
 
 \ /
  Last update: 2017-09-15 11:10    [W:0.229 / U:1.512 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site