diff options
Diffstat (limited to 'fs/crypto/policy.c')
-rw-r--r-- | fs/crypto/policy.c | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c index 0a95537fcef9..bcab94b29d10 100644 --- a/fs/crypto/policy.c +++ b/fs/crypto/policy.c @@ -11,6 +11,7 @@ */ #include <linux/random.h> +#include <linux/seq_file.h> #include <linux/string.h> #include <linux/mount.h> #include "fscrypt_private.h" @@ -616,3 +617,127 @@ int fscrypt_inherit_context(struct inode *parent, struct inode *child, return preload ? fscrypt_get_encryption_info(child): 0; } EXPORT_SYMBOL(fscrypt_inherit_context); + +/** + * fscrypt_set_test_dummy_encryption() - handle '-o test_dummy_encryption' + * @sb: the filesystem on which test_dummy_encryption is being specified + * @arg: the argument to the test_dummy_encryption option. + * If no argument was specified, then @arg->from == NULL. + * @dummy_ctx: the filesystem's current dummy context (input/output, see below) + * + * Handle the test_dummy_encryption mount option by creating a dummy encryption + * context, saving it in @dummy_ctx, and adding the corresponding dummy + * encryption key to the filesystem. If the @dummy_ctx is already set, then + * instead validate that it matches @arg. Don't support changing it via + * remount, as that is difficult to do safely. + * + * The reason we use an fscrypt_context rather than an fscrypt_policy is because + * we mustn't generate a new nonce each time we access a dummy-encrypted + * directory, as that would change the way filenames are encrypted. + * + * Return: 0 on success (dummy context set, or the same context is already set); + * -EEXIST if a different dummy context is already set; + * or another -errno value. + */ +int fscrypt_set_test_dummy_encryption(struct super_block *sb, + const substring_t *arg, + struct fscrypt_dummy_context *dummy_ctx) +{ + const char *argstr = "v1"; + const char *argstr_to_free = NULL; + struct fscrypt_key_specifier key_spec = { 0 }; + int version; + union fscrypt_context *ctx = NULL; + int err; + + if (arg->from) { + argstr = argstr_to_free = match_strdup(arg); + if (!argstr) + return -ENOMEM; + } + + if (!strcmp(argstr, "v1")) { + version = FSCRYPT_CONTEXT_V1; + key_spec.type = FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR; + memset(key_spec.u.descriptor, 0x42, + FSCRYPT_KEY_DESCRIPTOR_SIZE); + } else if (!strcmp(argstr, "v2")) { + version = FSCRYPT_CONTEXT_V2; + key_spec.type = FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER; + /* key_spec.u.identifier gets filled in when adding the key */ + } else { + err = -EINVAL; + goto out; + } + + if (dummy_ctx->ctx) { + /* + * Note: if we ever make test_dummy_encryption support + * specifying other encryption settings, such as the encryption + * modes, we'll need to compare those settings here. + */ + if (dummy_ctx->ctx->version == version) + err = 0; + else + err = -EEXIST; + goto out; + } + + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); + if (!ctx) { + err = -ENOMEM; + goto out; + } + + err = fscrypt_add_test_dummy_key(sb, &key_spec); + if (err) + goto out; + + ctx->version = version; + switch (ctx->version) { + case FSCRYPT_CONTEXT_V1: + ctx->v1.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS; + ctx->v1.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS; + memcpy(ctx->v1.master_key_descriptor, key_spec.u.descriptor, + FSCRYPT_KEY_DESCRIPTOR_SIZE); + break; + case FSCRYPT_CONTEXT_V2: + ctx->v2.contents_encryption_mode = FSCRYPT_MODE_AES_256_XTS; + ctx->v2.filenames_encryption_mode = FSCRYPT_MODE_AES_256_CTS; + memcpy(ctx->v2.master_key_identifier, key_spec.u.identifier, + FSCRYPT_KEY_IDENTIFIER_SIZE); + break; + default: + WARN_ON(1); + err = -EINVAL; + goto out; + } + dummy_ctx->ctx = ctx; + ctx = NULL; + err = 0; +out: + kfree(ctx); + kfree(argstr_to_free); + return err; +} +EXPORT_SYMBOL_GPL(fscrypt_set_test_dummy_encryption); + +/** + * fscrypt_show_test_dummy_encryption() - show '-o test_dummy_encryption' + * @seq: the seq_file to print the option to + * @sep: the separator character to use + * @sb: the filesystem whose options are being shown + * + * Show the test_dummy_encryption mount option, if it was specified. + * This is mainly used for /proc/mounts. + */ +void fscrypt_show_test_dummy_encryption(struct seq_file *seq, char sep, + struct super_block *sb) +{ + const union fscrypt_context *ctx = fscrypt_get_dummy_context(sb); + + if (!ctx) + return; + seq_printf(seq, "%ctest_dummy_encryption=v%d", sep, ctx->version); +} +EXPORT_SYMBOL_GPL(fscrypt_show_test_dummy_encryption); |