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Message-ID: <20230914081255.193502-5-ebiggers@kernel.org>
Date: Thu, 14 Sep 2023 01:12:54 -0700
From: Eric Biggers <ebiggers@...nel.org>
To: linux-fscrypt@...r.kernel.org
Cc: linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net,
linux-btrfs@...r.kernel.org, Jaegeuk Kim <jaegeuk@...nel.org>,
Theodore Ts'o <tytso@....edu>
Subject: [PATCH v2 4/5] fscrypt: replace get_ino_and_lblk_bits with just has_32bit_inodes
From: Eric Biggers <ebiggers@...gle.com>
Now that fs/crypto/ computes the filesystem's lblk_bits from its maximum
file size, it is no longer necessary for filesystems to provide
lblk_bits via fscrypt_operations::get_ino_and_lblk_bits.
It is still necessary for fs/crypto/ to retrieve ino_bits from the
filesystem. However, this is used only to decide whether inode numbers
fit in 32 bits. Also, ino_bits is static for all relevant filesystems,
i.e. it doesn't depend on the filesystem instance.
Therefore, in the interest of keeping things as simple as possible,
replace 'get_ino_and_lblk_bits' with a flag 'has_32bit_inodes'. This
can always be changed back to a function if a filesystem needs it to be
dynamic, but for now a static flag is all that's needed.
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
---
fs/crypto/policy.c | 33 +++++++++++++++------------------
fs/ext4/crypto.c | 9 +--------
fs/f2fs/super.c | 9 +--------
include/linux/fscrypt.h | 26 +++++++++++---------------
4 files changed, 28 insertions(+), 49 deletions(-)
diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
index 36bffc4d6228d..c8072a634af8f 100644
--- a/fs/crypto/policy.c
+++ b/fs/crypto/policy.c
@@ -118,11 +118,11 @@ static bool supported_direct_key_modes(const struct inode *inode,
}
static bool supported_iv_ino_lblk_policy(const struct fscrypt_policy_v2 *policy,
- const struct inode *inode,
- const char *type, int max_ino_bits)
+ const struct inode *inode)
{
+ const char *type = (policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64)
+ ? "IV_INO_LBLK_64" : "IV_INO_LBLK_32";
struct super_block *sb = inode->i_sb;
- int ino_bits = 64, lblk_bits = 64;
/*
* IV_INO_LBLK_* exist only because of hardware limitations, and
@@ -149,9 +149,15 @@ static bool supported_iv_ino_lblk_policy(const struct fscrypt_policy_v2 *policy,
type, sb->s_id);
return false;
}
- if (sb->s_cop->get_ino_and_lblk_bits)
- sb->s_cop->get_ino_and_lblk_bits(sb, &ino_bits, &lblk_bits);
- if (ino_bits > max_ino_bits) {
+
+ /*
+ * IV_INO_LBLK_64 requires that inode numbers fit in 32 bits.
+ * IV_INO_LBLK_32 hashes the inode number, so in principle it can
+ * support any length; however, currently the inode number is gotten
+ * from inode::i_ino which is 'unsigned long'. So for now the
+ * implementation limit is 32 bits, the same as IV_INO_LBLK_64.
+ */
+ if (!sb->s_cop->has_32bit_inodes) {
fscrypt_warn(inode,
"Can't use %s policy on filesystem '%s' because its maximum inode number is too large",
type, sb->s_id);
@@ -242,18 +248,9 @@ static bool fscrypt_supported_v2_policy(const struct fscrypt_policy_v2 *policy,
policy->filenames_encryption_mode))
return false;
- if ((policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) &&
- !supported_iv_ino_lblk_policy(policy, inode, "IV_INO_LBLK_64", 32))
- return false;
-
- /*
- * IV_INO_LBLK_32 hashes the inode number, so in principle it can
- * support any ino_bits. However, currently the inode number is gotten
- * from inode::i_ino which is 'unsigned long'. So for now the
- * implementation limit is 32 bits.
- */
- if ((policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) &&
- !supported_iv_ino_lblk_policy(policy, inode, "IV_INO_LBLK_32", 32))
+ if ((policy->flags & (FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64 |
+ FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) &&
+ !supported_iv_ino_lblk_policy(policy, inode))
return false;
if (memchr_inv(policy->__reserved, 0, sizeof(policy->__reserved))) {
diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
index a9221be67f2a7..2859d9569aa74 100644
--- a/fs/ext4/crypto.c
+++ b/fs/ext4/crypto.c
@@ -232,20 +232,13 @@ static bool ext4_has_stable_inodes(struct super_block *sb)
return ext4_has_feature_stable_inodes(sb);
}
-static void ext4_get_ino_and_lblk_bits(struct super_block *sb,
- int *ino_bits_ret, int *lblk_bits_ret)
-{
- *ino_bits_ret = 8 * sizeof(EXT4_SB(sb)->s_es->s_inodes_count);
- *lblk_bits_ret = 8 * sizeof(ext4_lblk_t);
-}
-
const struct fscrypt_operations ext4_cryptops = {
.needs_bounce_pages = 1,
+ .has_32bit_inodes = 1,
.legacy_key_prefix_for_backcompat = "ext4:",
.get_context = ext4_get_context,
.set_context = ext4_set_context,
.get_dummy_policy = ext4_get_dummy_policy,
.empty_dir = ext4_empty_dir,
.has_stable_inodes = ext4_has_stable_inodes,
- .get_ino_and_lblk_bits = ext4_get_ino_and_lblk_bits,
};
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 276535af5bf3c..7e8e510ef77af 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -3203,13 +3203,6 @@ static bool f2fs_has_stable_inodes(struct super_block *sb)
return true;
}
-static void f2fs_get_ino_and_lblk_bits(struct super_block *sb,
- int *ino_bits_ret, int *lblk_bits_ret)
-{
- *ino_bits_ret = 8 * sizeof(nid_t);
- *lblk_bits_ret = 8 * sizeof(block_t);
-}
-
static struct block_device **f2fs_get_devices(struct super_block *sb,
unsigned int *num_devs)
{
@@ -3232,13 +3225,13 @@ static struct block_device **f2fs_get_devices(struct super_block *sb,
static const struct fscrypt_operations f2fs_cryptops = {
.needs_bounce_pages = 1,
+ .has_32bit_inodes = 1,
.legacy_key_prefix_for_backcompat = "f2fs:",
.get_context = f2fs_get_context,
.set_context = f2fs_set_context,
.get_dummy_policy = f2fs_get_dummy_policy,
.empty_dir = f2fs_empty_dir,
.has_stable_inodes = f2fs_has_stable_inodes,
- .get_ino_and_lblk_bits = f2fs_get_ino_and_lblk_bits,
.get_devices = f2fs_get_devices,
};
#endif
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 32290e5fa9abb..32a3b59bea276 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -73,6 +73,17 @@ struct fscrypt_operations {
*/
unsigned int needs_bounce_pages : 1;
+ /*
+ * If set, then fs/crypto/ will allow the use of encryption settings
+ * that assume inode numbers fit in 32 bits (i.e.
+ * FSCRYPT_POLICY_FLAG_IV_INO_LBLK_{32,64}), provided that the other
+ * prerequisites for these settings are also met. This is only useful
+ * if the filesystem wants to support inline encryption hardware that is
+ * limited to 32-bit or 64-bit data unit numbers and where programming
+ * keyslots is very slow.
+ */
+ unsigned int has_32bit_inodes : 1;
+
/*
* This field exists only for backwards compatibility reasons and should
* only be set by the filesystems that are setting it already. It
@@ -150,21 +161,6 @@ struct fscrypt_operations {
*/
bool (*has_stable_inodes)(struct super_block *sb);
- /*
- * Get the number of bits that the filesystem uses to represent inode
- * numbers and file logical block numbers.
- *
- * By default, both of these are assumed to be 64-bit. This function
- * can be implemented to declare that either or both of these numbers is
- * shorter, which may allow the use of the
- * FSCRYPT_POLICY_FLAG_IV_INO_LBLK_{32,64} flags and/or the use of
- * inline crypto hardware whose maximum DUN length is less than 64 bits
- * (e.g., eMMC v5.2 spec compliant hardware). This function only needs
- * to be implemented if support for one of these features is needed.
- */
- void (*get_ino_and_lblk_bits)(struct super_block *sb,
- int *ino_bits_ret, int *lblk_bits_ret);
-
/*
* Return an array of pointers to the block devices to which the
* filesystem may write encrypted file contents, NULL if the filesystem
--
2.42.0
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