1 files changed, 335 insertions, 0 deletions
diff --git a/src/plugins/var-expand-crypt/var-expand-crypt-plugin.c b/src/plugins/var-expand-crypt/var-expand-crypt-plugin.c
new file mode 100644
index 0000000..1f6cce7
--- /dev/null
+++ b/src/plugins/var-expand-crypt/var-expand-crypt-plugin.c
@@ -0,0 +1,335 @@
+/* Copyright (c) 2003-2018 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "array.h"
+#include "hex-binary.h"
+#include "base64.h"
+#include "str.h"
+#include "strescape.h"
+#include "var-expand.h"
+#include "var-expand-private.h"
+#include "dcrypt.h"
+
+#define VAR_EXPAND_CRYPT_DEFAULT_ALGO "AES-256-CBC"
+
+struct module;
+
+enum crypt_field_format {
+	FORMAT_HEX,
+	FORMAT_BASE64
+};
+
+struct var_expand_crypt_context {
+	struct var_expand_context *ctx;
+	const char *algo;
+	string_t *iv;
+	string_t *enckey;
+	enum crypt_field_format format;
+	bool enc_result_only:1;
+};
+
+static bool var_expand_crypt_initialize(const char **error_r);
+
+void var_expand_crypt_init(struct module *module);
+void var_expand_crypt_deinit(void);
+void auth_var_expand_crypt_init(struct module *module);
+void auth_var_expand_crypt_deinit(void);
+
+static int
+var_expand_crypt_settings(struct var_expand_crypt_context *ctx,
+			  const char *const *args, const char **error_r)
+{
+	while(args != NULL && *args != NULL) {
+		const char *k = t_strcut(*args, '=');
+		const char *value = strchr(*args, '=');
+		if (value == NULL) {
+			args++;
+			continue;
+		} else {
+			value++;
+		}
+
+		if (strcmp(k, "iv") == 0) {
+			str_truncate(ctx->iv, 0);
+			if (var_expand_with_funcs(ctx->iv, value, ctx->ctx->table,
+						  ctx->ctx->func_table,
+						  ctx->ctx->context, error_r) < 0) {
+				return -1;
+			}
+			const char *hexiv = t_strdup(str_c(ctx->iv));
+			/* try to decode IV */
+			str_truncate(ctx->iv, 0);
+			hex_to_binary(hexiv, ctx->iv);
+		} if (strcmp(k, "noiv") == 0) {
+			ctx->enc_result_only = strcasecmp(value, "yes")==0;
+		} if (strcmp(k, "algo") == 0) {
+			ctx->algo = value;
+		} else if (strcmp(k, "key") == 0) {
+			str_truncate(ctx->enckey, 0);
+			if (var_expand_with_funcs(ctx->enckey, value,
+						  ctx->ctx->table,
+						  ctx->ctx->func_table,
+						  ctx->ctx->context,
+						  error_r) < 0) {
+				return -1;
+			}
+			const char *hexkey = t_strdup(str_c(ctx->enckey));
+			str_truncate(ctx->enckey, 0);
+			hex_to_binary(hexkey, ctx->enckey);
+		} else if (strcmp(k, "format") == 0) {
+			if (strcmp(value, "hex") == 0) {
+				ctx->format = FORMAT_HEX;
+			} else if (strcmp(value, "base64") == 0) {
+				ctx->format = FORMAT_BASE64;
+			} else {
+				*error_r = t_strdup_printf(
+					"Cannot parse hash arguments:"
+					"'%s' is not supported format",
+					value);
+				return -1;
+			}
+		}
+		args++;
+	}
+
+	if (ctx->algo == NULL) {
+		ctx->algo = "AES-256-CBC";
+	}
+
+	return 0;
+}
+
+static int
+var_expand_crypt(struct dcrypt_context_symmetric *dctx, buffer_t *key, buffer_t *iv,
+		 const buffer_t *input, buffer_t *output, const char **error_r)
+{
+	/* make sure IV is correct */
+	if (iv->used == 0) {
+		dcrypt_ctx_sym_set_key_iv_random(dctx);
+		/* acquire IV */
+		dcrypt_ctx_sym_get_iv(dctx, iv);
+	} else if (dcrypt_ctx_sym_get_iv_length(dctx) != iv->used) {
+		*error_r = t_strdup_printf("crypt: IV length invalid (%zu != %u)",
+					   iv->used,
+					   dcrypt_ctx_sym_get_iv_length(dctx));
+		return -1;
+	} else {
+		dcrypt_ctx_sym_set_iv(dctx, iv->data, iv->used);
+	}
+
+	if (dcrypt_ctx_sym_get_key_length(dctx) != key->used) {
+		*error_r = t_strdup_printf("crypt: Key length invalid (%zu != %u)",
+					   key->used,
+					   dcrypt_ctx_sym_get_key_length(dctx));
+		return -1;
+	} else {
+		dcrypt_ctx_sym_set_key(dctx, key->data, key->used);
+	}
+
+	if (!dcrypt_ctx_sym_init(dctx, error_r) ||
+	    !dcrypt_ctx_sym_update(dctx, input->data,
+				   input->used, output, error_r) ||
+	    !dcrypt_ctx_sym_final(dctx, output, error_r))
+		return -1;
+	return 0;
+}
+
+static int
+var_expand_encrypt(struct var_expand_context *_ctx,
+		   const char *key, const char *field,
+		   const char **result_r, const char **error_r)
+{
+	if (!var_expand_crypt_initialize(error_r))
+		return -1;
+
+	const char *p = strchr(key, ';');
+	const char *const *args = NULL;
+	const char *value;
+	struct var_expand_crypt_context ctx;
+	string_t *dest;
+	int ret = 0;
+
+	memset(&ctx, 0, sizeof(ctx));
+	ctx.ctx = _ctx;
+	ctx.format = FORMAT_HEX;
+
+	if (p != NULL) {
+		args = t_strsplit(p+1, ",");
+	}
+
+	string_t *field_value = t_str_new(64);
+	ctx.iv = t_str_new(64);
+	ctx.enckey = t_str_new(64);
+	string_t *tmp = t_str_new(128);
+
+	if ((ret = var_expand_long(_ctx, field, strlen(field),
+				   &value, error_r)) < 1) {
+		return ret;
+	}
+
+	if (*value == '\0') {
+		*result_r = value;
+		return ret;
+	}
+
+	if (var_expand_crypt_settings(&ctx, args, error_r) < 0)
+		return -1;
+
+	str_append(field_value, value);
+
+	struct dcrypt_context_symmetric *dctx;
+	if (!dcrypt_ctx_sym_create(ctx.algo, DCRYPT_MODE_ENCRYPT, &dctx, error_r))
+		return -1;
+
+	ret = var_expand_crypt(dctx, ctx.enckey, ctx.iv, field_value, tmp, error_r);
+	dcrypt_ctx_sym_destroy(&dctx);
+
+	if (ret == 0) {
+		/* makes compiler happy */
+		const char *enciv = "";
+		const char *res = "";
+
+		switch(ctx.format) {
+		case FORMAT_HEX:
+			enciv = binary_to_hex(ctx.iv->data, ctx.iv->used);
+			res = binary_to_hex(tmp->data, tmp->used);
+			break;
+		case FORMAT_BASE64:
+			dest = t_str_new(32);
+			base64_encode(ctx.iv->data, ctx.iv->used, dest);
+			enciv = str_c(dest);
+			dest = t_str_new(32);
+			base64_encode(tmp->data, tmp->used, dest);
+			res = str_c(dest);
+			break;
+		default:
+			i_unreached();
+		}
+		if (ctx.enc_result_only)
+			*result_r = t_strdup(res);
+		else
+			*result_r = t_strdup_printf("%s$%s$", enciv, res);
+		ret = 1;
+	}
+
+	return ret;
+}
+
+static int
+var_expand_decrypt(struct var_expand_context *_ctx,
+		   const char *key, const char *field,
+		   const char **result_r, const char **error_r)
+{
+	if (!var_expand_crypt_initialize(error_r))
+		return -1;
+
+	const char *p = strchr(key, ';');
+	const char *const *args = NULL;
+	const char *value;
+	struct var_expand_crypt_context ctx;
+	int ret = 0;
+
+	memset(&ctx, 0, sizeof(ctx));
+	ctx.ctx = _ctx;
+	ctx.format = FORMAT_HEX;
+
+	if (p != NULL) {
+		args = t_strsplit(p+1, ",");
+	}
+
+	string_t *field_value = t_str_new(64);
+	ctx.iv = t_str_new(64);
+	ctx.enckey = t_str_new(64);
+	string_t *tmp = t_str_new(128);
+
+	if ((ret = var_expand_long(_ctx, field, strlen(field),
+				   &value, error_r)) < 1) {
+		return ret;
+	}
+
+	if (*value == '\0') {
+		*result_r = value;
+		return ret;
+	}
+
+	if (var_expand_crypt_settings(&ctx, args, error_r) < 0)
+		return -1;
+
+	const char *encdata = value;
+	const char *enciv = "";
+
+	/* make sure IV is correct */
+	if (ctx.iv->used == 0 && (p = strchr(encdata, '$')) != NULL) {
+		/* see if IV can be taken from data */
+		enciv = t_strcut(encdata, '$');
+		encdata = t_strcut(p+1,'$');
+	}
+
+	str_truncate(field_value, 0);
+
+	/* try to decode iv and encdata */
+	switch(ctx.format) {
+	case FORMAT_HEX:
+		if (ctx.iv->used == 0)
+			hex_to_binary(enciv, ctx.iv);
+		hex_to_binary(encdata, field_value);
+		break;
+	case FORMAT_BASE64:
+		if (ctx.iv->used == 0)
+			str_append_str(ctx.iv, t_base64_decode_str(enciv));
+		str_append_str(field_value, t_base64_decode_str(encdata));
+		break;
+	}
+
+	if (ctx.iv->used == 0) {
+		*error_r = t_strdup_printf("decrypt: IV missing");
+		return -1;
+	}
+
+	struct dcrypt_context_symmetric *dctx;
+	if (!dcrypt_ctx_sym_create(ctx.algo, DCRYPT_MODE_DECRYPT, &dctx, error_r))
+		return -1;
+	ret = var_expand_crypt(dctx, ctx.enckey, ctx.iv, field_value, tmp, error_r);
+	dcrypt_ctx_sym_destroy(&dctx);
+
+	if (ret == 0) {
+		*result_r = str_c(tmp);
+		ret = 1;
+	}
+
+	return ret;
+}
+
+static const struct var_expand_extension_func_table funcs[] = {
+	{ "encrypt", var_expand_encrypt },
+	{ "decrypt", var_expand_decrypt },
+	{ NULL, NULL, }
+};
+
+static bool var_expand_crypt_initialize(const char **error_r)
+{
+	return dcrypt_initialize(NULL, NULL, error_r);
+}
+
+void var_expand_crypt_init(struct module *module ATTR_UNUSED)
+{
+	var_expand_register_func_array(funcs);
+	/* do not initialize dcrypt here - saves alot of memory
+	   to not load openssl every time. Only load it if
+	   needed */
+}
+
+void var_expand_crypt_deinit(void)
+{
+	var_expand_unregister_func_array(funcs);
+}
+
+void auth_var_expand_crypt_init(struct module *module)
+{
+	var_expand_crypt_init(module);
+}
+
+void auth_var_expand_crypt_deinit(void)
+{
+	var_expand_crypt_deinit();
+}