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ext4: fix up test_dummy_encryption handling for new mount API
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Since ext4 was converted to the new mount API, the test_dummy_encryption
mount option isn't being handled entirely correctly, because the needed
fscrypt_set_test_dummy_encryption() helper function combines
parsing/checking/applying into one function.  That doesn't work well
with the new mount API, which split these into separate steps.

This was sort of okay anyway, due to the parsing logic that was copied
from fscrypt_set_test_dummy_encryption() into ext4_parse_param(),
combined with an additional check in ext4_check_test_dummy_encryption().
However, these overlooked the case of changing the value of
test_dummy_encryption on remount, which isn't allowed but ext4 wasn't
detecting until ext4_apply_options() when it's too late to fail.
Another bug is that if test_dummy_encryption was specified multiple
times with an argument, memory was leaked.

Fix this up properly by using the new helper functions that allow
splitting up the parse/check/apply steps for test_dummy_encryption.

Fixes: cebe85d ("ext4: switch to the new mount api")
Signed-off-by: Eric Biggers <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Theodore Ts'o <[email protected]>
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@ebiggers @tytso
ebiggers authored and tytso committed Jun 18, 2022
1 parent 4efd9f0 commit 8545605
Showing 1 changed file with 71 additions and 63 deletions.
134 changes: 71 additions & 63 deletions fs/ext4/super.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -87,7 +87,7 @@ static struct inode *ext4_get_journal_inode(struct super_block *sb,
static int ext4_validate_options(struct fs_context *fc);
static int ext4_check_opt_consistency(struct fs_context *fc,
struct super_block *sb);
static int ext4_apply_options(struct fs_context *fc, struct super_block *sb);
static void ext4_apply_options(struct fs_context *fc, struct super_block *sb);
static int ext4_parse_param(struct fs_context *fc, struct fs_parameter *param);
static int ext4_get_tree(struct fs_context *fc);
static int ext4_reconfigure(struct fs_context *fc);
Expand Down Expand Up @@ -1870,31 +1870,12 @@ ext4_sb_read_encoding(const struct ext4_super_block *es)
}
#endif

static int ext4_set_test_dummy_encryption(struct super_block *sb, char *arg)
{
#ifdef CONFIG_FS_ENCRYPTION
struct ext4_sb_info *sbi = EXT4_SB(sb);
int err;

err = fscrypt_set_test_dummy_encryption(sb, arg,
&sbi->s_dummy_enc_policy);
if (err) {
ext4_msg(sb, KERN_WARNING,
"Error while setting test dummy encryption [%d]", err);
return err;
}
ext4_msg(sb, KERN_WARNING, "Test dummy encryption mode enabled");
#endif
return 0;
}

#define EXT4_SPEC_JQUOTA (1 << 0)
#define EXT4_SPEC_JQFMT (1 << 1)
#define EXT4_SPEC_DATAJ (1 << 2)
#define EXT4_SPEC_SB_BLOCK (1 << 3)
#define EXT4_SPEC_JOURNAL_DEV (1 << 4)
#define EXT4_SPEC_JOURNAL_IOPRIO (1 << 5)
#define EXT4_SPEC_DUMMY_ENCRYPTION (1 << 6)
#define EXT4_SPEC_s_want_extra_isize (1 << 7)
#define EXT4_SPEC_s_max_batch_time (1 << 8)
#define EXT4_SPEC_s_min_batch_time (1 << 9)
Expand All @@ -1911,7 +1892,7 @@ static int ext4_set_test_dummy_encryption(struct super_block *sb, char *arg)

struct ext4_fs_context {
char *s_qf_names[EXT4_MAXQUOTAS];
char *test_dummy_enc_arg;
struct fscrypt_dummy_policy dummy_enc_policy;
int s_jquota_fmt; /* Format of quota to use */
#ifdef CONFIG_EXT4_DEBUG
int s_fc_debug_max_replay;
Expand Down Expand Up @@ -1953,7 +1934,7 @@ static void ext4_fc_free(struct fs_context *fc)
for (i = 0; i < EXT4_MAXQUOTAS; i++)
kfree(ctx->s_qf_names[i]);

kfree(ctx->test_dummy_enc_arg);
fscrypt_free_dummy_policy(&ctx->dummy_enc_policy);
kfree(ctx);
}

Expand Down Expand Up @@ -2029,6 +2010,29 @@ static int unnote_qf_name(struct fs_context *fc, int qtype)
}
#endif

static int ext4_parse_test_dummy_encryption(const struct fs_parameter *param,
struct ext4_fs_context *ctx)
{
int err;

if (!IS_ENABLED(CONFIG_FS_ENCRYPTION)) {
ext4_msg(NULL, KERN_WARNING,
"test_dummy_encryption option not supported");
return -EINVAL;
}
err = fscrypt_parse_test_dummy_encryption(param,
&ctx->dummy_enc_policy);
if (err == -EINVAL) {
ext4_msg(NULL, KERN_WARNING,
"Value of option \"%s\" is unrecognized", param->key);
} else if (err == -EEXIST) {
ext4_msg(NULL, KERN_WARNING,
"Conflicting test_dummy_encryption options");
return -EINVAL;
}
return err;
}

#define EXT4_SET_CTX(name) \
static inline void ctx_set_##name(struct ext4_fs_context *ctx, \
unsigned long flag) \
Expand Down Expand Up @@ -2291,29 +2295,7 @@ static int ext4_parse_param(struct fs_context *fc, struct fs_parameter *param)
ctx->spec |= EXT4_SPEC_JOURNAL_IOPRIO;
return 0;
case Opt_test_dummy_encryption:
#ifdef CONFIG_FS_ENCRYPTION
if (param->type == fs_value_is_flag) {
ctx->spec |= EXT4_SPEC_DUMMY_ENCRYPTION;
ctx->test_dummy_enc_arg = NULL;
return 0;
}
if (*param->string &&
!(!strcmp(param->string, "v1") ||
!strcmp(param->string, "v2"))) {
ext4_msg(NULL, KERN_WARNING,
"Value of option \"%s\" is unrecognized",
param->key);
return -EINVAL;
}
ctx->spec |= EXT4_SPEC_DUMMY_ENCRYPTION;
ctx->test_dummy_enc_arg = kmemdup_nul(param->string, param->size,
GFP_KERNEL);
return 0;
#else
ext4_msg(NULL, KERN_WARNING,
"test_dummy_encryption option not supported");
return -EINVAL;
#endif
return ext4_parse_test_dummy_encryption(param, ctx);
case Opt_dax:
case Opt_dax_type:
#ifdef CONFIG_FS_DAX
Expand Down Expand Up @@ -2504,7 +2486,8 @@ static int parse_apply_sb_mount_options(struct super_block *sb,
if (s_ctx->spec & EXT4_SPEC_JOURNAL_IOPRIO)
m_ctx->journal_ioprio = s_ctx->journal_ioprio;

ret = ext4_apply_options(fc, sb);
ext4_apply_options(fc, sb);
ret = 0;

out_free:
if (fc) {
Expand Down Expand Up @@ -2673,11 +2656,11 @@ static int ext4_check_quota_consistency(struct fs_context *fc,
static int ext4_check_test_dummy_encryption(const struct fs_context *fc,
struct super_block *sb)
{
#ifdef CONFIG_FS_ENCRYPTION
const struct ext4_fs_context *ctx = fc->fs_private;
const struct ext4_sb_info *sbi = EXT4_SB(sb);
int err;

if (!(ctx->spec & EXT4_SPEC_DUMMY_ENCRYPTION))
if (!fscrypt_is_dummy_policy_set(&ctx->dummy_enc_policy))
return 0;

if (!ext4_has_feature_encrypt(sb)) {
Expand All @@ -2691,14 +2674,46 @@ static int ext4_check_test_dummy_encryption(const struct fs_context *fc,
* needed to allow it to be set or changed during remount. We do allow
* it to be specified during remount, but only if there is no change.
*/
if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE &&
!sbi->s_dummy_enc_policy.policy) {
if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) {
if (fscrypt_dummy_policies_equal(&sbi->s_dummy_enc_policy,
&ctx->dummy_enc_policy))
return 0;
ext4_msg(NULL, KERN_WARNING,
"Can't set test_dummy_encryption on remount");
"Can't set or change test_dummy_encryption on remount");
return -EINVAL;
}
#endif /* CONFIG_FS_ENCRYPTION */
return 0;
/* Also make sure s_mount_opts didn't contain a conflicting value. */
if (fscrypt_is_dummy_policy_set(&sbi->s_dummy_enc_policy)) {
if (fscrypt_dummy_policies_equal(&sbi->s_dummy_enc_policy,
&ctx->dummy_enc_policy))
return 0;
ext4_msg(NULL, KERN_WARNING,
"Conflicting test_dummy_encryption options");
return -EINVAL;
}
/*
* fscrypt_add_test_dummy_key() technically changes the super_block, so
* technically it should be delayed until ext4_apply_options() like the
* other changes. But since we never get here for remounts (see above),
* and this is the last chance to report errors, we do it here.
*/
err = fscrypt_add_test_dummy_key(sb, &ctx->dummy_enc_policy);
if (err)
ext4_msg(NULL, KERN_WARNING,
"Error adding test dummy encryption key [%d]", err);
return err;
}

static void ext4_apply_test_dummy_encryption(struct ext4_fs_context *ctx,
struct super_block *sb)
{
if (!fscrypt_is_dummy_policy_set(&ctx->dummy_enc_policy) ||
/* if already set, it was already verified to be the same */
fscrypt_is_dummy_policy_set(&EXT4_SB(sb)->s_dummy_enc_policy))
return;
EXT4_SB(sb)->s_dummy_enc_policy = ctx->dummy_enc_policy;
memset(&ctx->dummy_enc_policy, 0, sizeof(ctx->dummy_enc_policy));
ext4_msg(sb, KERN_WARNING, "Test dummy encryption mode enabled");
}

static int ext4_check_opt_consistency(struct fs_context *fc,
Expand Down Expand Up @@ -2785,11 +2800,10 @@ static int ext4_check_opt_consistency(struct fs_context *fc,
return ext4_check_quota_consistency(fc, sb);
}

static int ext4_apply_options(struct fs_context *fc, struct super_block *sb)
static void ext4_apply_options(struct fs_context *fc, struct super_block *sb)
{
struct ext4_fs_context *ctx = fc->fs_private;
struct ext4_sb_info *sbi = fc->s_fs_info;
int ret = 0;

sbi->s_mount_opt &= ~ctx->mask_s_mount_opt;
sbi->s_mount_opt |= ctx->vals_s_mount_opt;
Expand Down Expand Up @@ -2825,11 +2839,7 @@ static int ext4_apply_options(struct fs_context *fc, struct super_block *sb)
#endif

ext4_apply_quota_options(fc, sb);

if (ctx->spec & EXT4_SPEC_DUMMY_ENCRYPTION)
ret = ext4_set_test_dummy_encryption(sb, ctx->test_dummy_enc_arg);

return ret;
ext4_apply_test_dummy_encryption(ctx, sb);
}


Expand Down Expand Up @@ -4552,9 +4562,7 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
if (err < 0)
goto failed_mount;

err = ext4_apply_options(fc, sb);
if (err < 0)
goto failed_mount;
ext4_apply_options(fc, sb);

#if IS_ENABLED(CONFIG_UNICODE)
if (ext4_has_feature_casefold(sb) && !sb->s_encoding) {
Expand Down

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