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Date: Wed, 22 Feb 2023 13:12:10 +0000
From: Tudor Ambarus <tudor.ambarus@...aro.org>
To: tytso@....edu, darrick.wong@...cle.com, djwong@...nel.org,
adilger.kernel@...ger.ca
Cc: linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
joneslee@...gle.com, Tudor Ambarus <tudor.ambarus@...aro.org>
Subject: [PATCH 2/3] ext4: fsmap: Consolidate fsmap_head checks
Sanity checks should be done the soonest possible to avoid superfluous
computations when user provides wrong data. Gather all the checks on
user provided data in a single method and call it immediately after
copying the data from user.
Signed-off-by: Tudor Ambarus <tudor.ambarus@...aro.org>
---
fs/ext4/fsmap.c | 52 ++++++++++++++++++++++++++++++++++++-------------
fs/ext4/fsmap.h | 3 +++
fs/ext4/ioctl.c | 17 +++-------------
3 files changed, 44 insertions(+), 28 deletions(-)
diff --git a/fs/ext4/fsmap.c b/fs/ext4/fsmap.c
index b5289378a761..a27d9f0967b7 100644
--- a/fs/ext4/fsmap.c
+++ b/fs/ext4/fsmap.c
@@ -9,6 +9,7 @@
#include "fsmap.h"
#include "mballoc.h"
#include <linux/sort.h>
+#include <linux/string.h>
#include <linux/list_sort.h>
#include <trace/events/ext4.h>
@@ -571,7 +572,7 @@ static int ext4_getfsmap_datadev(struct super_block *sb,
/* Do we recognize the device? */
static bool ext4_getfsmap_is_valid_device(struct super_block *sb,
- struct ext4_fsmap *fm)
+ const struct fsmap *fm)
{
if (fm->fmr_device == 0 || fm->fmr_device == UINT_MAX ||
fm->fmr_device == new_encode_dev(sb->s_bdev->bd_dev))
@@ -583,17 +584,19 @@ static bool ext4_getfsmap_is_valid_device(struct super_block *sb,
}
/* Ensure that the low key is less than the high key. */
-static bool ext4_getfsmap_check_keys(struct ext4_fsmap *low_key,
- struct ext4_fsmap *high_key)
+static bool ext4_getfsmap_check_keys(const struct fsmap *low_key,
+ const struct fsmap *high_key)
{
+ u64 l_fmr_phys = low_key->fmr_physical + low_key->fmr_length;
+
if (low_key->fmr_device > high_key->fmr_device)
return false;
if (low_key->fmr_device < high_key->fmr_device)
return true;
- if (low_key->fmr_physical > high_key->fmr_physical)
+ if (l_fmr_phys > high_key->fmr_physical)
return false;
- if (low_key->fmr_physical < high_key->fmr_physical)
+ if (l_fmr_phys < high_key->fmr_physical)
return true;
if (low_key->fmr_owner > high_key->fmr_owner)
@@ -604,6 +607,36 @@ static bool ext4_getfsmap_check_keys(struct ext4_fsmap *low_key,
return false;
}
+int ext4_fsmap_check_head(struct super_block *sb,
+ const struct fsmap_head *head)
+{
+ const struct fsmap *l = &head->fmh_keys[0];
+ const struct fsmap *h = &head->fmh_keys[1];
+
+ if (memchr_inv(head->fmh_reserved, 0, sizeof(head->fmh_reserved)) ||
+ memchr_inv(l->fmr_reserved, 0, sizeof(l->fmr_reserved)) ||
+ memchr_inv(h->fmr_reserved, 0, sizeof(h->fmr_reserved)))
+ return -EINVAL;
+ /*
+ * ext4 doesn't report file extents at all, so the only valid
+ * file offsets are the magic ones (all zeroes or all ones).
+ */
+ if (l->fmr_offset || (h->fmr_offset != 0 && h->fmr_offset != -1ULL))
+ return -EINVAL;
+
+ if (head->fmh_iflags & ~FMH_IF_VALID)
+ return -EINVAL;
+
+ if (!ext4_getfsmap_is_valid_device(sb, l) ||
+ !ext4_getfsmap_is_valid_device(sb, h))
+ return -EINVAL;
+
+ if (!ext4_getfsmap_check_keys(l, h))
+ return -EINVAL;
+
+ return 0;
+}
+
#define EXT4_GETFSMAP_DEVS 2
/*
* Get filesystem's extents as described in head, and format for
@@ -635,12 +668,6 @@ int ext4_getfsmap(struct super_block *sb, struct ext4_fsmap_head *head,
int i;
int error = 0;
- if (head->fmh_iflags & ~FMH_IF_VALID)
- return -EINVAL;
- if (!ext4_getfsmap_is_valid_device(sb, &head->fmh_keys[0]) ||
- !ext4_getfsmap_is_valid_device(sb, &head->fmh_keys[1]))
- return -EINVAL;
-
head->fmh_entries = 0;
/* Set up our device handlers. */
@@ -673,9 +700,6 @@ int ext4_getfsmap(struct super_block *sb, struct ext4_fsmap_head *head,
dkeys[0].fmr_length = 0;
memset(&dkeys[1], 0xFF, sizeof(struct ext4_fsmap));
- if (!ext4_getfsmap_check_keys(dkeys, &head->fmh_keys[1]))
- return -EINVAL;
-
info.gfi_next_fsblk = head->fmh_keys[0].fmr_physical +
head->fmh_keys[0].fmr_length;
info.gfi_formatter = formatter;
diff --git a/fs/ext4/fsmap.h b/fs/ext4/fsmap.h
index ac642be2302e..8325258def7b 100644
--- a/fs/ext4/fsmap.h
+++ b/fs/ext4/fsmap.h
@@ -8,6 +8,7 @@
#define __EXT4_FSMAP_H__
struct fsmap;
+struct fsmap_head;
/* internal fsmap representation */
struct ext4_fsmap {
@@ -32,6 +33,8 @@ void ext4_fsmap_from_internal(struct super_block *sb, struct fsmap *dest,
struct ext4_fsmap *src);
void ext4_fsmap_to_internal(struct super_block *sb, struct ext4_fsmap *dest,
struct fsmap *src);
+int ext4_fsmap_check_head(struct super_block *sb,
+ const struct fsmap_head *head);
/* fsmap to userspace formatter - copy to user & advance pointer */
typedef int (*ext4_fsmap_format_t)(struct ext4_fsmap *, void *);
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 8067ccda34e4..eb0ecb012e6a 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -874,20 +874,9 @@ static int ext4_ioc_getfsmap(struct super_block *sb,
if (copy_from_user(&head, arg, sizeof(struct fsmap_head)))
return -EFAULT;
- if (memchr_inv(head.fmh_reserved, 0, sizeof(head.fmh_reserved)) ||
- memchr_inv(head.fmh_keys[0].fmr_reserved, 0,
- sizeof(head.fmh_keys[0].fmr_reserved)) ||
- memchr_inv(head.fmh_keys[1].fmr_reserved, 0,
- sizeof(head.fmh_keys[1].fmr_reserved)))
- return -EINVAL;
- /*
- * ext4 doesn't report file extents at all, so the only valid
- * file offsets are the magic ones (all zeroes or all ones).
- */
- if (head.fmh_keys[0].fmr_offset ||
- (head.fmh_keys[1].fmr_offset != 0 &&
- head.fmh_keys[1].fmr_offset != -1ULL))
- return -EINVAL;
+ error = ext4_fsmap_check_head(sb, &head);
+ if (error)
+ return error;
xhead.fmh_iflags = head.fmh_iflags;
xhead.fmh_count = head.fmh_count;
--
2.39.2.637.g21b0678d19-goog
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