1 files changed, 426 insertions, 0 deletions
diff --git a/runtime/libgcry.c b/runtime/libgcry.c
new file mode 100644
index 00000000..51c10af4
--- /dev/null
+++ b/runtime/libgcry.c
@@ -0,0 +1,426 @@
+/* gcry.c - rsyslog's libgcrypt based crypto provider
+ *
+ * Copyright 2013 Adiscon GmbH.
+ *
+ * We need to store some additional information in support of encryption.
+ * For this, we create a side-file, which is named like the actual log
+ * file, but with the suffix ".encinfo" appended. It contains the following
+ * records:
+ * IV:<hex>   The initial vector used at block start. Also indicates start
+ *            start of block.
+ * END:<int>  The end offset of the block, as uint64_t in decimal notation.
+ *            This is used during encryption to know when the current
+ *            encryption block ends.
+ * For the current implementation, there must always be an IV record
+ * followed by an END record. Each records is LF-terminated. Record
+ * types can simply be extended in the future by specifying new 
+ * types (like "IV") before the colon.
+ * To identify a file as rsyslog encryption info file, it must start with
+ * the line "FILETYPE:rsyslog-enrcyption-info"
+ * There are some size constraints: the recordtype must be 31 bytes at
+ * most and the actual value (between : and LF) must be 1023 bytes at most.
+ *
+ * This file is part of rsyslog.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *       -or-
+ *       see COPYING.ASL20 in the source distribution
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+#include <stdio.h>
+#include <gcrypt.h>
+#include <sys/stat.h>
+#include <sys/uio.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include "rsyslog.h"
+#include "libgcry.h"
+
+
+static rsRetVal
+eiWriteRec(gcryfile gf, char *recHdr, size_t lenRecHdr, char *buf, size_t lenBuf)
+{
+	struct iovec iov[3];
+	ssize_t nwritten, towrite;
+	DEFiRet;
+
+	iov[0].iov_base = recHdr;
+	iov[0].iov_len = lenRecHdr;
+	iov[1].iov_base = buf;
+	iov[1].iov_len = lenBuf;
+	iov[2].iov_base = "\n";
+	iov[2].iov_len = 1;
+	towrite = iov[0].iov_len + iov[1].iov_len + iov[2].iov_len;
+	nwritten = writev(gf->fd, iov, sizeof(iov)/sizeof(struct iovec));
+	if(nwritten != towrite) {
+		DBGPRINTF("eiWrite%s: error writing file, towrite %d, "
+			"nwritten %d\n", recHdr, (int) towrite, (int) nwritten);
+		ABORT_FINALIZE(RS_RET_EI_WR_ERR);
+	}
+	DBGPRINTF("encryption info file %s: written %s, len %d\n",
+		  recHdr, gf->eiName, (int) nwritten);
+finalize_it:
+	RETiRet;
+}
+
+static rsRetVal
+eiOpenRead(gcryfile gf)
+{
+	DEFiRet;
+	gf->fd = open((char*)gf->eiName, O_RDONLY|O_NOCTTY|O_CLOEXEC);
+	if(gf->fd == -1) {
+		ABORT_FINALIZE(errno == ENOENT ? RS_RET_EI_NO_EXISTS : RS_RET_EI_OPN_ERR);
+	}
+finalize_it:
+	RETiRet;
+}
+
+
+static rsRetVal
+eiCheckFiletype(gcryfile gf)
+{
+	char hdrBuf[128];
+	size_t toRead, didRead;
+	DEFiRet;
+
+	CHKiRet(eiOpenRead(gf));
+	if(Debug) memset(hdrBuf, 0, sizeof(hdrBuf)); /* for dbgprintf below! */
+	toRead = sizeof("FILETYPE:")-1 + sizeof(RSGCRY_FILETYPE_NAME)-1 + 1;
+	didRead = read(gf->fd, hdrBuf, toRead);
+	close(gf->fd);
+	DBGPRINTF("eiCheckFiletype read %d bytes: '%s'\n", didRead, hdrBuf);
+	if(   didRead != toRead
+	   || strncmp(hdrBuf, "FILETYPE:" RSGCRY_FILETYPE_NAME "\n", toRead))
+		iRet = RS_RET_EI_INVLD_FILE;
+finalize_it:
+	RETiRet;
+}
+
+static rsRetVal
+eiOpenAppend(gcryfile gf)
+{
+	rsRetVal localRet;
+	DEFiRet;
+	localRet = eiCheckFiletype(gf);
+	if(localRet == RS_RET_OK) {
+		gf->fd = open((char*)gf->eiName,
+			       O_WRONLY|O_APPEND|O_NOCTTY|O_CLOEXEC, 0600);
+		if(gf->fd == -1) {
+			ABORT_FINALIZE(RS_RET_EI_OPN_ERR);
+		}
+	} else if(localRet == RS_RET_EI_NO_EXISTS) {
+		/* looks like we need to create a new file */
+		gf->fd = open((char*)gf->eiName,
+			       O_WRONLY|O_CREAT|O_NOCTTY|O_CLOEXEC, 0600);
+		if(gf->fd == -1) {
+			ABORT_FINALIZE(RS_RET_EI_OPN_ERR);
+		}
+		CHKiRet(eiWriteRec(gf, "FILETYPE:", 9, RSGCRY_FILETYPE_NAME,
+			    sizeof(RSGCRY_FILETYPE_NAME)-1));
+	} else {
+		gf->fd = -1;
+		ABORT_FINALIZE(localRet);
+	}
+	DBGPRINTF("encryption info file %s: opened as #%d\n",
+		gf->eiName, gf->fd);
+finalize_it:
+	RETiRet;
+}
+
+static rsRetVal
+eiWriteIV(gcryfile gf, uchar *iv)
+{
+	static const char hexchars[16] =
+	   {'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'};
+	unsigned iSrc, iDst;
+	char hex[4096];
+	DEFiRet;
+
+	if(gf->blkLength > sizeof(hex)/2) {
+		DBGPRINTF("eiWriteIV: crypto block len way too large, aborting "
+			  "write");
+		ABORT_FINALIZE(RS_RET_ERR);
+	}
+
+	for(iSrc = iDst = 0 ; iSrc < gf->blkLength ; ++iSrc) {
+		hex[iDst++] = hexchars[iv[iSrc]>>4];
+		hex[iDst++] = hexchars[iv[iSrc]&0x0f];
+	}
+
+	iRet = eiWriteRec(gf, "IV:", 3, hex, gf->blkLength*2);
+finalize_it:
+	RETiRet;
+}
+
+/* we do not return an error state, as we MUST close the file,
+ * no matter what happens.
+ */
+static void
+eiClose(gcryfile gf, off64_t offsLogfile)
+{
+	char offs[21];
+	size_t len;
+	if(gf->fd == -1)
+		return;
+	/* 2^64 is 20 digits, so the snprintf buffer is large enough */
+	len = snprintf(offs, sizeof(offs), "%lld", offsLogfile);
+	eiWriteRec(gf, "END:", 4, offs, len);
+	close(gf->fd);
+	DBGPRINTF("encryption info file %s: closed\n", gf->eiName);
+}
+
+static rsRetVal
+gcryfileConstruct(gcryctx ctx, gcryfile *pgf, uchar *logfn)
+{
+	char fn[MAXFNAME+1];
+	gcryfile gf;
+	DEFiRet;
+
+	CHKmalloc(gf = calloc(1, sizeof(struct gcryfile_s)));
+	gf->ctx = ctx;
+	snprintf(fn, sizeof(fn), "%s%s", logfn, ENCINFO_SUFFIX);
+	fn[MAXFNAME] = '\0'; /* be on save side */
+	gf->eiName = (uchar*) strdup(fn);
+	*pgf = gf;
+finalize_it:
+	RETiRet;
+}
+
+
+gcryctx
+gcryCtxNew(void)
+{
+	gcryctx ctx;
+	ctx = calloc(1, sizeof(struct gcryctx_s));
+	ctx->algo = GCRY_CIPHER_AES128;
+	ctx->mode = GCRY_CIPHER_MODE_CBC;
+	return ctx;
+}
+
+int
+gcryfileDestruct(gcryfile gf, off64_t offsLogfile)
+{
+	int r = 0;
+	if(gf == NULL)
+		goto done;
+
+	eiClose(gf, offsLogfile);
+	free(gf->eiName);
+	free(gf);
+done:	return r;
+}
+void
+rsgcryCtxDel(gcryctx ctx)
+{
+	if(ctx != NULL) {
+		free(ctx);
+	}
+}
+
+static inline void
+addPadding(gcryfile pF, uchar *buf, size_t *plen)
+{
+	unsigned i;
+	size_t nPad;
+	nPad = (pF->blkLength - *plen % pF->blkLength) % pF->blkLength;
+	DBGPRINTF("libgcry: addPadding %d chars, blkLength %d, mod %d, pad %d\n",
+		  *plen, pF->blkLength, *plen % pF->blkLength, nPad);
+	for(i = 0 ; i < nPad ; ++i)
+		buf[(*plen)+i] = 0x00;
+	(*plen)+= nPad;
+}
+
+static inline void
+removePadding(char *buf, size_t *plen)
+{
+	unsigned len = (unsigned) *plen;
+	unsigned iSrc, iDst;
+	char *frstNUL;
+
+	frstNUL = strchr(buf, 0x00);
+	if(frstNUL == NULL)
+		goto done;
+	iDst = iSrc = frstNUL - buf;
+
+	while(iSrc < len) {
+		if(buf[iSrc] != 0x00)
+			buf[iDst++] = buf[iSrc];
+		++iSrc;
+	}
+
+	*plen = iDst;
+done:	return;
+}
+
+/* returns 0 on succes, positive if key length does not match and key
+ * of return value size is required.
+ */
+int
+rsgcrySetKey(gcryctx ctx, unsigned char *key, uint16_t keyLen)
+{
+	uint16_t reqKeyLen;
+	int r;
+
+	reqKeyLen = gcry_cipher_get_algo_keylen(ctx->algo);
+	if(keyLen != reqKeyLen) {
+		r = reqKeyLen;
+		goto done;
+	}
+	ctx->keyLen = keyLen;
+	ctx->key = malloc(keyLen);
+	memcpy(ctx->key, key, keyLen);
+	r = 0;
+done:	return r;
+}
+
+rsRetVal
+rsgcrySetMode(gcryctx ctx, uchar *modename)
+{
+	int mode;
+	DEFiRet;
+
+	mode = rsgcryModename2Mode((char *)modename);
+	if(mode == GCRY_CIPHER_MODE_NONE) {
+		ABORT_FINALIZE(RS_RET_CRY_INVLD_MODE);
+	}
+	ctx->mode = mode;
+finalize_it:
+	RETiRet;
+}
+
+rsRetVal
+rsgcrySetAlgo(gcryctx ctx, uchar *algoname)
+{
+	int algo;
+	DEFiRet;
+
+	algo = rsgcryAlgoname2Algo((char *)algoname);
+	if(algo == GCRY_CIPHER_NONE) {
+		ABORT_FINALIZE(RS_RET_CRY_INVLD_ALGO);
+	}
+	ctx->algo = algo;
+finalize_it:
+	RETiRet;
+}
+
+/* As of some Linux and security expert I spoke to, /dev/urandom
+ * provides very strong random numbers, even if it runs out of
+ * entropy. As far as he knew, this is save for all applications
+ * (and he had good proof that I currently am not permitted to
+ * reproduce). -- rgerhards, 2013-03-04
+ */
+void
+seedIV(gcryfile gf, uchar **iv)
+{
+	int fd;
+
+	*iv = malloc(gf->blkLength); /* do NOT zero-out! */
+	/* if we cannot obtain data from /dev/urandom, we use whatever
+	 * is present at the current memory location as random data. Of
+	 * course, this is very weak and we should consider a different
+	 * option, especially when not running under Linux (for Linux,
+	 * unavailability of /dev/urandom is just a theoretic thing, it
+	 * will always work...).  -- TODO -- rgerhards, 2013-03-06
+	 */
+	if((fd = open("/dev/urandom", O_RDONLY)) > 0) {
+		if(read(fd, *iv, gf->blkLength)) {}; /* keep compiler happy */
+		close(fd);
+	}
+}
+
+rsRetVal
+rsgcryInitCrypt(gcryctx ctx, gcryfile *pgf, uchar *fname)
+{
+	gcry_error_t gcryError;
+	gcryfile gf = NULL;
+	uchar *iv = NULL;
+	DEFiRet;
+
+	CHKiRet(gcryfileConstruct(ctx, &gf, fname));
+
+	gf->blkLength = gcry_cipher_get_algo_blklen(ctx->algo);
+
+	gcryError = gcry_cipher_open(&gf->chd, ctx->algo, ctx->mode, 0);
+	if (gcryError) {
+		dbgprintf("gcry_cipher_open failed:  %s/%s\n",
+			gcry_strsource(gcryError),
+			gcry_strerror(gcryError));
+		ABORT_FINALIZE(RS_RET_ERR);
+	}
+
+	gcryError = gcry_cipher_setkey(gf->chd, gf->ctx->key, gf->ctx->keyLen);
+	if (gcryError) {
+		dbgprintf("gcry_cipher_setkey failed:  %s/%s\n",
+			gcry_strsource(gcryError),
+			gcry_strerror(gcryError));
+		ABORT_FINALIZE(RS_RET_ERR);
+	}
+
+	seedIV(gf, &iv);
+	gcryError = gcry_cipher_setiv(gf->chd, iv, gf->blkLength);
+	if (gcryError) {
+		dbgprintf("gcry_cipher_setiv failed:  %s/%s\n",
+			gcry_strsource(gcryError),
+			gcry_strerror(gcryError));
+		ABORT_FINALIZE(RS_RET_ERR);
+	}
+	CHKiRet(eiOpenAppend(gf));
+	CHKiRet(eiWriteIV(gf, iv));
+	*pgf = gf;
+finalize_it:
+	free(iv);
+	if(iRet != RS_RET_OK && gf != NULL)
+		gcryfileDestruct(gf, -1);
+	RETiRet;
+}
+
+int
+rsgcryEncrypt(gcryfile pF, uchar *buf, size_t *len)
+{
+	int gcryError;
+	DEFiRet;
+	
+	if(*len == 0)
+		FINALIZE;
+
+	addPadding(pF, buf, len);
+	gcryError = gcry_cipher_encrypt(pF->chd, buf, *len, NULL, 0);
+	if(gcryError) {
+		dbgprintf("gcry_cipher_encrypt failed:  %s/%s\n",
+			gcry_strsource(gcryError),
+			gcry_strerror(gcryError));
+		ABORT_FINALIZE(RS_RET_ERR);
+	}
+finalize_it:
+	RETiRet;
+}
+
+
+/* module-init dummy for potential later use */
+int
+rsgcryInit(void)
+{
+	return 0;
+}
+
+/* module-deinit dummy for potential later use */
+void
+rsgcryExit(void)
+{
+	return;
+}