Commit b925acb8 authored by Eric Biggers's avatar Eric Biggers
Browse files

ext4: add support for IV_INO_LBLK_64 encryption policies 



IV_INO_LBLK_64 encryption policies have special requirements from the
filesystem beyond those of the existing encryption policies:

- Inode numbers must never change, even if the filesystem is resized.
- Inode numbers must be <= 32 bits.
- File logical block numbers must be <= 32 bits.

ext4 has 32-bit inode and file logical block numbers.  However,
resize2fs can re-number inodes when shrinking an ext4 filesystem.

However, typically the people who would want to use this format don't
care about filesystem shrinking.  They'd be fine with a solution that
just prevents the filesystem from being shrunk.

Therefore, add a new feature flag EXT4_FEATURE_COMPAT_STABLE_INODES that
will do exactly that.  Then wire up the fscrypt_operations to expose
this flag to fs/crypto/, so that it allows IV_INO_LBLK_64 policies when
this flag is set.

Acked-by: default avatarTheodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
parent b103fb76

fs/ext4/ext4.h

+2 −0
Original line number Diff line number Diff line
@@ -1678,6 +1678,7 @@ static inline bool ext4_verity_in_progress(struct inode *inode) 
#define EXT4_FEATURE_COMPAT_RESIZE_INODE	0x0010

#define EXT4_FEATURE_COMPAT_DIR_INDEX		0x0020

#define EXT4_FEATURE_COMPAT_SPARSE_SUPER2	0x0200

#define EXT4_FEATURE_COMPAT_STABLE_INODES	0x0800



#define EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER	0x0001

#define EXT4_FEATURE_RO_COMPAT_LARGE_FILE	0x0002
@@ -1779,6 +1780,7 @@ EXT4_FEATURE_COMPAT_FUNCS(xattr, EXT_ATTR) 
EXT4_FEATURE_COMPAT_FUNCS(resize_inode,		RESIZE_INODE)

EXT4_FEATURE_COMPAT_FUNCS(dir_index,		DIR_INDEX)

EXT4_FEATURE_COMPAT_FUNCS(sparse_super2,	SPARSE_SUPER2)

EXT4_FEATURE_COMPAT_FUNCS(stable_inodes,	STABLE_INODES)



EXT4_FEATURE_RO_COMPAT_FUNCS(sparse_super,	SPARSE_SUPER)

EXT4_FEATURE_RO_COMPAT_FUNCS(large_file,	LARGE_FILE)

fs/ext4/super.c

+14 −0
Original line number Diff line number Diff line
@@ -1345,6 +1345,18 @@ static bool ext4_dummy_context(struct inode *inode) 
	return DUMMY_ENCRYPTION_ENABLED(EXT4_SB(inode->i_sb));

}



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);

}



static const struct fscrypt_operations ext4_cryptops = {

	.key_prefix		= "ext4:",

	.get_context		= ext4_get_context,
@@ -1352,6 +1364,8 @@ static const struct fscrypt_operations ext4_cryptops = { 
	.dummy_context		= ext4_dummy_context,

	.empty_dir		= ext4_empty_dir,

	.max_namelen		= EXT4_NAME_LEN,

	.has_stable_inodes	= ext4_has_stable_inodes,

	.get_ino_and_lblk_bits	= ext4_get_ino_and_lblk_bits,

};

#endif

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