From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: hch@infradead.org, akpm@linux-foundation.org, tytso@mit.edu,
viro@zeniv.linux.org.uk, darrick.wong@oracle.com
Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH 1/2] mm: set S_SWAPFILE on blockdev swap devices
Date: Thu, 15 Aug 2019 09:05:47 -0700 [thread overview]
Message-ID: <156588514761.111054.15427341787826850860.stgit@magnolia> (raw)
In-Reply-To: <156588514105.111054.13645634739408399209.stgit@magnolia>
From: Darrick J. Wong <darrick.wong@oracle.com>
Set S_SWAPFILE on block device inodes so that they have the same
protections as a swap flie.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
mm/swapfile.c | 31 +++++++++++++++----------------
1 file changed, 15 insertions(+), 16 deletions(-)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 0789a762ce2f..a53b7c49b40e 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2368,9 +2368,8 @@ EXPORT_SYMBOL_GPL(add_swap_extent);
* requirements, they are simply tossed out - we will never use those blocks
* for swapping.
*
- * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This
- * prevents root from shooting her foot off by ftruncating an in-use swapfile,
- * which will scribble on the fs.
+ * For all swap devices we set S_SWAPFILE across the life of the swapon. This
+ * prevents users from writing to the swap device, which will corrupt memory.
*
* The amount of disk space which a single swap extent represents varies.
* Typically it is in the 1-4 megabyte range. So we can have hundreds of
@@ -2661,13 +2660,14 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
inode = mapping->host;
if (S_ISBLK(inode->i_mode)) {
struct block_device *bdev = I_BDEV(inode);
+
set_blocksize(bdev, old_block_size);
blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
- } else {
- inode_lock(inode);
- inode->i_flags &= ~S_SWAPFILE;
- inode_unlock(inode);
}
+
+ inode_lock(inode);
+ inode->i_flags &= ~S_SWAPFILE;
+ inode_unlock(inode);
filp_close(swap_file, NULL);
/*
@@ -2890,11 +2890,11 @@ static int claim_swapfile(struct swap_info_struct *p, struct inode *inode)
p->flags |= SWP_BLKDEV;
} else if (S_ISREG(inode->i_mode)) {
p->bdev = inode->i_sb->s_bdev;
- inode_lock(inode);
- if (IS_SWAPFILE(inode))
- return -EBUSY;
- } else
- return -EINVAL;
+ }
+
+ inode_lock(inode);
+ if (IS_SWAPFILE(inode))
+ return -EBUSY;
return 0;
}
@@ -3295,8 +3295,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
atomic_inc(&proc_poll_event);
wake_up_interruptible(&proc_poll_wait);
- if (S_ISREG(inode->i_mode))
- inode->i_flags |= S_SWAPFILE;
+ inode->i_flags |= S_SWAPFILE;
error = 0;
goto out;
bad_swap:
@@ -3318,7 +3317,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
if (inced_nr_rotate_swap)
atomic_dec(&nr_rotate_swap);
if (swap_file) {
- if (inode && S_ISREG(inode->i_mode)) {
+ if (inode) {
inode_unlock(inode);
inode = NULL;
}
@@ -3331,7 +3330,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
}
if (name)
putname(name);
- if (inode && S_ISREG(inode->i_mode))
+ if (inode)
inode_unlock(inode);
if (!error)
enable_swap_slots_cache();
next prev parent reply other threads:[~2019-08-15 16:06 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-15 16:05 [PATCH v3 0/2] vfs: make active swap files unwritable Darrick J. Wong
2019-08-15 16:05 ` Darrick J. Wong [this message]
2019-08-16 6:39 ` [PATCH 1/2] mm: set S_SWAPFILE on blockdev swap devices Christoph Hellwig
2019-08-15 16:05 ` [PATCH 2/2] vfs: don't allow writes to swap files Darrick J. Wong
2019-08-16 6:41 ` Christoph Hellwig
2019-08-16 6:48 ` Darrick J. Wong
2019-08-16 16:19 ` [PATCH v2 " Darrick J. Wong
2019-08-18 8:39 ` Christoph Hellwig
2019-08-15 16:34 ` [PATCH RFC 3/2] fstests: check that we can't write " Darrick J. Wong
2019-08-15 21:26 ` Andrew Morton
2019-08-16 2:13 ` Darrick J. Wong
2019-08-17 2:05 ` [PATCH v2 " Darrick J. Wong
-- strict thread matches above, loose matches on Subject: below --
2019-06-28 18:35 [PATCH v2 0/2] vfs: make active swap files unwritable Darrick J. Wong
2019-06-28 18:35 ` [PATCH 1/2] mm: set S_SWAPFILE on blockdev swap devices Darrick J. Wong
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