/*- * Copyright (c) 2016 Konrad Witaszczyk * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "pjdlog.h" #define DECRYPTCORE_CRASHDIR "/var/crash" static void usage(void) { pjdlog_exitx(1, "usage: decryptcore [-fLv] -p privatekeyfile -k keyfile -e encryptedcore -c core\n" " decryptcore [-fLv] [-d crashdir] -p privatekeyfile -n dumpnr"); } static int wait_for_process(pid_t pid) { int status; if (waitpid(pid, &status, WUNTRACED | WEXITED) == -1) { pjdlog_errno(LOG_ERR, "Unable to wait for a child process"); return (1); } if (WIFEXITED(status)) return (WEXITSTATUS(status)); return (1); } static struct kerneldumpkey * read_key(int kfd) { struct kerneldumpkey *kdk; ssize_t size; size_t kdksize; PJDLOG_ASSERT(kfd >= 0); kdksize = sizeof(*kdk); kdk = calloc(1, kdksize); if (kdk == NULL) { pjdlog_errno(LOG_ERR, "Unable to allocate kernel dump key"); goto failed; } size = read(kfd, kdk, kdksize); if (size == (ssize_t)kdksize) { kdk->kdk_encryptedkeysize = dtoh32(kdk->kdk_encryptedkeysize); kdksize += (size_t)kdk->kdk_encryptedkeysize; kdk = realloc(kdk, kdksize); if (kdk == NULL) { pjdlog_errno(LOG_ERR, "Unable to reallocate kernel dump key"); goto failed; } size += read(kfd, &kdk->kdk_encryptedkey, kdk->kdk_encryptedkeysize); } if (size != (ssize_t)kdksize) { pjdlog_errno(LOG_ERR, "Unable to read key"); goto failed; } return (kdk); failed: free(kdk); return (NULL); } static bool decrypt(int ofd, const char *privkeyfile, const char *keyfile, const char *input) { uint8_t buf[KERNELDUMP_BUFFER_SIZE], key[KERNELDUMP_KEY_MAX_SIZE], chachaiv[4 * 4]; EVP_CIPHER_CTX *ctx; const EVP_CIPHER *cipher; FILE *fp; struct kerneldumpkey *kdk; RSA *privkey; int ifd, kfd, olen, privkeysize; ssize_t bytes; pid_t pid; PJDLOG_ASSERT(ofd >= 0); PJDLOG_ASSERT(privkeyfile != NULL); PJDLOG_ASSERT(keyfile != NULL); PJDLOG_ASSERT(input != NULL); ctx = NULL; privkey = NULL; /* * Decrypt a core dump in a child process so we can unlink a partially * decrypted core if the child process fails. */ pid = fork(); if (pid == -1) { pjdlog_errno(LOG_ERR, "Unable to create child process"); close(ofd); return (false); } if (pid > 0) { close(ofd); return (wait_for_process(pid) == 0); } kfd = open(keyfile, O_RDONLY); if (kfd == -1) { pjdlog_errno(LOG_ERR, "Unable to open %s", keyfile); goto failed; } ifd = open(input, O_RDONLY); if (ifd == -1) { pjdlog_errno(LOG_ERR, "Unable to open %s", input); goto failed; } fp = fopen(privkeyfile, "r"); if (fp == NULL) { pjdlog_errno(LOG_ERR, "Unable to open %s", privkeyfile); goto failed; } /* * Obsolescent OpenSSL only knows about /dev/random, and needs to * pre-seed before entering cap mode. For whatever reason, * RSA_pub_encrypt uses the internal PRNG. */ #if OPENSSL_VERSION_NUMBER < 0x10100000L { unsigned char c[1]; RAND_bytes(c, 1); } ERR_load_crypto_strings(); #else OPENSSL_init_crypto(OPENSSL_INIT_LOAD_CONFIG, NULL); #endif caph_cache_catpages(); if (caph_enter() < 0) { pjdlog_errno(LOG_ERR, "Unable to enter capability mode"); goto failed; } privkey = RSA_new(); if (privkey == NULL) { pjdlog_error("Unable to allocate an RSA structure: %s", ERR_error_string(ERR_get_error(), NULL)); goto failed; } ctx = EVP_CIPHER_CTX_new(); if (ctx == NULL) goto failed; kdk = read_key(kfd); close(kfd); if (kdk == NULL) goto failed; privkey = PEM_read_RSAPrivateKey(fp, &privkey, NULL, NULL); fclose(fp); if (privkey == NULL) { pjdlog_error("Unable to read data from %s.", privkeyfile); goto failed; } privkeysize = RSA_size(privkey); if (privkeysize != (int)kdk->kdk_encryptedkeysize) { pjdlog_error("RSA modulus size mismatch: equals %db and should be %ub.", 8 * privkeysize, 8 * kdk->kdk_encryptedkeysize); goto failed; } switch (kdk->kdk_encryption) { case KERNELDUMP_ENC_AES_256_CBC: cipher = EVP_aes_256_cbc(); break; case KERNELDUMP_ENC_CHACHA20: cipher = EVP_chacha20(); break; default: pjdlog_error("Invalid encryption algorithm."); goto failed; } if (RSA_private_decrypt(kdk->kdk_encryptedkeysize, kdk->kdk_encryptedkey, key, privkey, RSA_PKCS1_OAEP_PADDING) != sizeof(key) && /* Fallback to deprecated, formerly-used PKCS 1.5 padding. */ RSA_private_decrypt(kdk->kdk_encryptedkeysize, kdk->kdk_encryptedkey, key, privkey, RSA_PKCS1_PADDING) != sizeof(key)) { pjdlog_error("Unable to decrypt key: %s", ERR_error_string(ERR_get_error(), NULL)); goto failed; } RSA_free(privkey); privkey = NULL; if (kdk->kdk_encryption == KERNELDUMP_ENC_CHACHA20) { /* * OpenSSL treats the IV as 4 little-endian 32 bit integers. * * The first two represent a 64-bit counter, where the low half * is the first 32-bit word. * * Start at counter block zero... */ memset(chachaiv, 0, 4 * 2); /* * And use the IV specified by the dump. */ memcpy(&chachaiv[4 * 2], kdk->kdk_iv, 4 * 2); EVP_DecryptInit_ex(ctx, cipher, NULL, key, chachaiv); } else EVP_DecryptInit_ex(ctx, cipher, NULL, key, kdk->kdk_iv); EVP_CIPHER_CTX_set_padding(ctx, 0); explicit_bzero(key, sizeof(key)); do { bytes = read(ifd, buf, sizeof(buf)); if (bytes < 0) { pjdlog_errno(LOG_ERR, "Unable to read data from %s", input); goto failed; } if (bytes > 0) { if (EVP_DecryptUpdate(ctx, buf, &olen, buf, bytes) == 0) { pjdlog_error("Unable to decrypt core."); goto failed; } } else { if (EVP_DecryptFinal_ex(ctx, buf, &olen) == 0) { pjdlog_error("Unable to decrypt core."); goto failed; } } if (olen > 0 && write(ofd, buf, olen) != olen) { pjdlog_errno(LOG_ERR, "Unable to write core"); goto failed; } } while (bytes > 0); explicit_bzero(buf, sizeof(buf)); EVP_CIPHER_CTX_free(ctx); exit(0); failed: explicit_bzero(key, sizeof(key)); explicit_bzero(buf, sizeof(buf)); RSA_free(privkey); if (ctx != NULL) EVP_CIPHER_CTX_free(ctx); exit(1); } int main(int argc, char **argv) { char core[PATH_MAX], encryptedcore[PATH_MAX], keyfile[PATH_MAX]; const char *crashdir, *dumpnr, *privatekey; int ch, debug, error, ofd; size_t ii; bool force, usesyslog; error = 1; pjdlog_init(PJDLOG_MODE_STD); pjdlog_prefix_set("(decryptcore) "); debug = 0; *core = '\0'; crashdir = NULL; dumpnr = NULL; *encryptedcore = '\0'; force = false; *keyfile = '\0'; privatekey = NULL; usesyslog = false; while ((ch = getopt(argc, argv, "Lc:d:e:fk:n:p:v")) != -1) { switch (ch) { case 'L': usesyslog = true; break; case 'c': if (strlcpy(core, optarg, sizeof(core)) >= sizeof(core)) pjdlog_exitx(1, "Core file path is too long."); break; case 'd': crashdir = optarg; break; case 'e': if (strlcpy(encryptedcore, optarg, sizeof(encryptedcore)) >= sizeof(encryptedcore)) { pjdlog_exitx(1, "Encrypted core file path is too long."); } break; case 'f': force = true; break; case 'k': if (strlcpy(keyfile, optarg, sizeof(keyfile)) >= sizeof(keyfile)) { pjdlog_exitx(1, "Key file path is too long."); } break; case 'n': dumpnr = optarg; break; case 'p': privatekey = optarg; break; case 'v': debug++; break; default: usage(); } } argc -= optind; argv += optind; if (argc != 0) usage(); /* Verify mutually exclusive options. */ if ((crashdir != NULL || dumpnr != NULL) && (*keyfile != '\0' || *encryptedcore != '\0' || *core != '\0')) { usage(); } /* * Set key, encryptedcore and core file names using crashdir and dumpnr. */ if (dumpnr != NULL) { for (ii = 0; ii < strnlen(dumpnr, PATH_MAX); ii++) { if (isdigit((int)dumpnr[ii]) == 0) usage(); } if (crashdir == NULL) crashdir = DECRYPTCORE_CRASHDIR; PJDLOG_VERIFY(snprintf(keyfile, sizeof(keyfile), "%s/key.%s", crashdir, dumpnr) > 0); PJDLOG_VERIFY(snprintf(core, sizeof(core), "%s/vmcore.%s", crashdir, dumpnr) > 0); PJDLOG_VERIFY(snprintf(encryptedcore, sizeof(encryptedcore), "%s/vmcore_encrypted.%s", crashdir, dumpnr) > 0); } if (privatekey == NULL || *keyfile == '\0' || *encryptedcore == '\0' || *core == '\0') { usage(); } if (usesyslog) pjdlog_mode_set(PJDLOG_MODE_SYSLOG); pjdlog_debug_set(debug); if (force && unlink(core) == -1 && errno != ENOENT) { pjdlog_errno(LOG_ERR, "Unable to remove old core"); goto out; } ofd = open(core, O_WRONLY | O_CREAT | O_EXCL, 0600); if (ofd == -1) { pjdlog_errno(LOG_ERR, "Unable to open %s", core); goto out; } if (!decrypt(ofd, privatekey, keyfile, encryptedcore)) { if (unlink(core) == -1 && errno != ENOENT) pjdlog_errno(LOG_ERR, "Unable to remove core"); goto out; } error = 0; out: pjdlog_fini(); exit(error); }