From: Eric Biggers <ebiggers@xxxxxxxxxx>
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@xxxxxxxxxx>
---
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 7b34949e49de6..32709dad9762b 100644
--- a/fs/crypto/policy.c
+++ b/fs/crypto/policy.c
@@ -111,25 +111,25 @@ static bool supported_direct_key_modes(const struct inode *inode,
if (mode->ivsize < offsetofend(union fscrypt_iv, nonce)) {
fscrypt_warn(inode, "Direct key flag not allowed with %s",
mode->friendly_name);
return false;
}
return true;
}
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
* currently the only known use case for them involves AES-256-XTS.
* That's also all we test currently. For these reasons, for now only
* allow AES-256-XTS here. This can be relaxed later if a use case for
* IV_INO_LBLK_* with other encryption modes arises.
*/
if (policy->contents_encryption_mode != FSCRYPT_MODE_AES_256_XTS) {
fscrypt_warn(inode,
@@ -142,23 +142,29 @@ static bool supported_iv_ino_lblk_policy(const struct fscrypt_policy_v2 *policy,
* It's unsafe to include inode numbers in the IVs if the filesystem can
* potentially renumber inodes, e.g. via filesystem shrinking.
*/
if (!sb->s_cop->has_stable_inodes ||
!sb->s_cop->has_stable_inodes(sb)) {
fscrypt_warn(inode,
"Can't use %s policy on filesystem '%s' because it doesn't have stable inode numbers",
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 and IV_INO_LBLK_32 both require that inode numbers fit
+ * in 32 bits. In principle, IV_INO_LBLK_32 could support longer inode
+ * numbers because it hashes the inode number; 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 (!sb->s_cop->has_32bit_inodes) {
fscrypt_warn(inode,
"Can't use %s policy on filesystem '%s' because its inode numbers are too long",
type, sb->s_id);
return false;
}
/*
* IV_INO_LBLK_64 and IV_INO_LBLK_32 both require that file logical
* block numbers fit in 32 bits.
*/
@@ -235,32 +241,23 @@ static bool fscrypt_supported_v2_policy(const struct fscrypt_policy_v2 *policy,
fscrypt_warn(inode, "Mutually exclusive encryption flags (0x%02x)",
policy->flags);
return false;
}
if ((policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) &&
!supported_direct_key_modes(inode, policy->contents_encryption_mode,
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))) {
fscrypt_warn(inode, "Reserved bits set in encryption policy");
return false;
}
return true;
}
diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
index 5cd7bcfae46b2..9e36731701baa 100644
--- a/fs/ext4/crypto.c
+++ b/fs/ext4/crypto.c
@@ -225,27 +225,20 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
static const union fscrypt_policy *ext4_get_dummy_policy(struct super_block *sb)
{
return EXT4_SB(sb)->s_dummy_enc_policy.policy;
}
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 = "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 55aa0ed531f22..c449157132643 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -3196,27 +3196,20 @@ static int f2fs_set_context(struct inode *inode, const void *ctx, size_t len,
static const union fscrypt_policy *f2fs_get_dummy_policy(struct super_block *sb)
{
return F2FS_OPTION(F2FS_SB(sb)).dummy_enc_policy.policy;
}
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)
{
struct f2fs_sb_info *sbi = F2FS_SB(sb);
struct block_device **devs;
int i;
if (!f2fs_is_multi_device(sbi))
return NULL;
@@ -3225,27 +3218,27 @@ static struct block_device **f2fs_get_devices(struct super_block *sb,
return ERR_PTR(-ENOMEM);
for (i = 0; i < sbi->s_ndevs; i++)
devs[i] = FDEV(i).bdev;
*num_devs = sbi->s_ndevs;
return devs;
}
static const struct fscrypt_operations f2fs_cryptops = {
.needs_bounce_pages = 1,
+ .has_32bit_inodes = 1,
.legacy_key_prefix = "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
static struct inode *f2fs_nfs_get_inode(struct super_block *sb,
u64 ino, u32 generation)
{
struct f2fs_sb_info *sbi = F2FS_SB(sb);
struct inode *inode;
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 4505078e89b7e..09a3cacbf62ad 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -67,20 +67,31 @@ struct fscrypt_operations {
* first time an encryption key is set up for a file. The bounce page
* pool is required by the following functions:
*
* - fscrypt_encrypt_pagecache_blocks()
* - fscrypt_zeroout_range() for files not using inline crypto
*
* If the filesystem doesn't use those, it doesn't need to set this.
*/
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
* contains the filesystem-specific key description prefix that is
* accepted for "logon" keys for v1 fscrypt policies. This
* functionality is deprecated in favor of the generic prefix
* "fscrypt:", which itself is deprecated in favor of the filesystem
* keyring ioctls such as FS_IOC_ADD_ENCRYPTION_KEY. Filesystems that
* are newly adding fscrypt support should not set this field.
*/
@@ -144,35 +155,20 @@ struct fscrypt_operations {
* Filesystems only need to implement this function if they want to
* support the FSCRYPT_POLICY_FLAG_IV_INO_LBLK_{32,64} flags. These
* flags are designed to work around the limitations of UFS and eMMC
* inline crypto hardware, and they shouldn't be used in scenarios where
* such hardware isn't being used.
*
* Leaving this NULL is equivalent to always returning false.
*/
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
* only has a single such block device, or an ERR_PTR() on error.
*
* On successful non-NULL return, *num_devs is set to the number of
* devices in the returned array. The caller must free the returned
* array using kfree().
*
* If the filesystem can use multiple block devices (other than block
--
2.42.0
