lkml.org 
[lkml]   [2019]   [Feb]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Date
Subject[PATCH 3.16 054/305] ext4: fix EXT4_IOC_SWAP_BOOT
3.16.63-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Theodore Ts'o <tytso@mit.edu>

commit 18aded17492088962ef43f00825179598b3e8c58 upstream.

The code EXT4_IOC_SWAP_BOOT ioctl hasn't been updated in a while, and
it's a bit broken with respect to more modern ext4 kernels, especially
metadata checksums.

Other problems fixed with this commit:

* Don't allow installing a DAX, swap file, or an encrypted file as a
boot loader.

* Respect the immutable and append-only flags.

* Wait until any DIO operations are finished *before* calling
truncate_inode_pages().

* Don't swap inode->i_flags, since these flags have nothing to do with
the inode blocks --- and it will give the IMA/audit code heartburn
when the inode is evicted.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reported-by: syzbot+e81ccd4744c6c4f71354@syzkaller.appspotmail.com
[bwh: Backported to 3.16:
- Drop IS_ENCRYPTED() check
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/ext4/ioctl.c | 33 +++++++++++++++++++++++++++------
1 file changed, 27 insertions(+), 6 deletions(-)

--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -64,7 +64,6 @@ static void swap_inode_data(struct inode
ei1 = EXT4_I(inode1);
ei2 = EXT4_I(inode2);

- memswap(&inode1->i_flags, &inode2->i_flags, sizeof(inode1->i_flags));
memswap(&inode1->i_version, &inode2->i_version,
sizeof(inode1->i_version));
memswap(&inode1->i_blocks, &inode2->i_blocks,
@@ -86,6 +85,21 @@ static void swap_inode_data(struct inode
i_size_write(inode2, isize);
}

+static void reset_inode_seed(struct inode *inode)
+{
+ struct ext4_inode_info *ei = EXT4_I(inode);
+ struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+ __le32 inum = cpu_to_le32(inode->i_ino);
+ __le32 gen = cpu_to_le32(inode->i_generation);
+ __u32 csum;
+
+ if (!ext4_has_metadata_csum(inode->i_sb))
+ return;
+
+ csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&inum, sizeof(inum));
+ ei->i_csum_seed = ext4_chksum(sbi, csum, (__u8 *)&gen, sizeof(gen));
+}
+
/**
* Swap the information from the given @inode and the inode
* EXT4_BOOT_LOADER_INO. It will basically swap i_data and all other
@@ -104,10 +118,13 @@ static long swap_inode_boot_loader(struc
struct ext4_inode_info *ei_bl;
struct ext4_sb_info *sbi = EXT4_SB(sb);

- if (inode->i_nlink != 1 || !S_ISREG(inode->i_mode))
+ if (inode->i_nlink != 1 || !S_ISREG(inode->i_mode) ||
+ IS_SWAPFILE(inode) ||
+ ext4_has_inline_data(inode))
return -EINVAL;

- if (!inode_owner_or_capable(inode) || !capable(CAP_SYS_ADMIN))
+ if (IS_RDONLY(inode) || IS_APPEND(inode) || IS_IMMUTABLE(inode) ||
+ !inode_owner_or_capable(inode) || !capable(CAP_SYS_ADMIN))
return -EPERM;

inode_bl = ext4_iget(sb, EXT4_BOOT_LOADER_INO);
@@ -122,15 +139,15 @@ static long swap_inode_boot_loader(struc
* that only 1 swap_inode_boot_loader is running. */
lock_two_nondirectories(inode, inode_bl);

- truncate_inode_pages(&inode->i_data, 0);
- truncate_inode_pages(&inode_bl->i_data, 0);
-
/* Wait for all existing dio workers */
ext4_inode_block_unlocked_dio(inode);
ext4_inode_block_unlocked_dio(inode_bl);
inode_dio_wait(inode);
inode_dio_wait(inode_bl);

+ truncate_inode_pages(&inode->i_data, 0);
+ truncate_inode_pages(&inode_bl->i_data, 0);
+
handle = ext4_journal_start(inode_bl, EXT4_HT_MOVE_EXTENTS, 2);
if (IS_ERR(handle)) {
err = -EINVAL;
@@ -166,6 +183,8 @@ static long swap_inode_boot_loader(struc
inode->i_generation = sbi->s_next_generation++;
inode_bl->i_generation = sbi->s_next_generation++;
spin_unlock(&sbi->s_next_gen_lock);
+ reset_inode_seed(inode);
+ reset_inode_seed(inode_bl);

ext4_discard_preallocations(inode);

@@ -176,6 +195,7 @@ static long swap_inode_boot_loader(struc
inode->i_ino, err);
/* Revert all changes: */
swap_inode_data(inode, inode_bl);
+ ext4_mark_inode_dirty(handle, inode);
} else {
err = ext4_mark_inode_dirty(handle, inode_bl);
if (err < 0) {
@@ -185,6 +205,7 @@ static long swap_inode_boot_loader(struc
/* Revert all changes: */
swap_inode_data(inode, inode_bl);
ext4_mark_inode_dirty(handle, inode);
+ ext4_mark_inode_dirty(handle, inode_bl);
}
}
ext4_journal_stop(handle);
\
 
 \ /
  Last update: 2019-02-03 15:32    [W:1.001 / U:3.340 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site