improve usage message and start working on revoker logic
[oweals/ucert.git] / ucert.c
diff --git a/ucert.c b/ucert.c
index 9afca1ced37fb9eebf285901189583343f0acf4a..13975d10e97dacc3b2645feb2f75bb29407472d9 100644 (file)
--- a/ucert.c
+++ b/ucert.c
@@ -33,6 +33,8 @@
 #include <libubox/vlist.h>
 #include <libubox/blobmsg_json.h>
 
+#include "usign.h"
+
 #define CERT_BUF_LEN 4096
 
 static enum {
@@ -57,6 +59,15 @@ static const struct blob_attr_info cert_policy[CERT_ATTR_MAX] = {
        [CERT_ATTR_PAYLOAD] = { .type = BLOB_ATTR_NESTED },
 };
 
+enum cert_cont_attr {
+       CERT_CT_ATTR_PAYLOAD,
+       CERT_CT_ATTR_MAX
+};
+
+static const struct blobmsg_policy cert_cont_policy[CERT_CT_ATTR_MAX] = {
+       [CERT_CT_ATTR_PAYLOAD] = { .name = "ucert", .type = BLOBMSG_TYPE_TABLE },
+};
+
 enum cert_payload_attr {
        CERT_PL_ATTR_CERTTYPE,
        CERT_PL_ATTR_CERTID,
@@ -74,73 +85,476 @@ enum certtype_id {
 };
 
 static const struct blobmsg_policy cert_payload_policy[CERT_PL_ATTR_MAX] = {
-       [CERT_PL_ATTR_CERTTYPE] = { .type = BLOBMSG_TYPE_INT8 },
-       [CERT_PL_ATTR_CERTID] = { .type = BLOBMSG_TYPE_INT64 },
-       [CERT_PL_ATTR_VALIDFROMTIME] = { .type = BLOBMSG_TYPE_INT64 },
-       [CERT_PL_ATTR_EXPIRETIME] = { .type = BLOBMSG_TYPE_INT64 },
-       [CERT_PL_ATTR_PUBKEY] = { .type = BLOBMSG_TYPE_STRING },
-       [CERT_PL_ATTR_KEY_FINGERPRINT] = { .type = BLOBMSG_TYPE_STRING },
+       [CERT_PL_ATTR_CERTTYPE] = { .name = "certtype", .type = BLOBMSG_TYPE_INT32 },
+       [CERT_PL_ATTR_CERTID] = { .name = "certid", .type = BLOBMSG_TYPE_INT32 },
+       [CERT_PL_ATTR_VALIDFROMTIME] = { .name = "validfrom", .type = BLOBMSG_TYPE_INT64 },
+       [CERT_PL_ATTR_EXPIRETIME] = { .name = "expiresat", .type = BLOBMSG_TYPE_INT64 },
+       [CERT_PL_ATTR_PUBKEY] = { .name = "pubkey", .type = BLOBMSG_TYPE_STRING },
+       [CERT_PL_ATTR_KEY_FINGERPRINT] = { .name = "fingerprint", .type = BLOBMSG_TYPE_STRING },
 };
 
+struct cert_object {
+       struct list_head list;
+       struct blob_attr *cert[CERT_ATTR_MAX];
+};
 
-static int cert_load(const char *certfile, struct blob_attr *certtb[]) {
+static int write_file(const char *filename, void *buf, size_t len, bool append) {
        FILE *f;
-       struct blob_buf certbuf;
-       int ret = 0;
-       char filebuf[CERT_BUF_LEN];
-       int len;
+       size_t outlen;
+
+       f = fopen(filename, append?"a":"w");
+       if (!f)
+               return 1;
 
-       blob_buf_init(&certbuf, 0);
+       outlen = fwrite(buf, 1, len, f);
+       fclose(f);
+       return (outlen == len);
+}
+
+static int cert_load(const char *certfile, struct list_head *chain) {
+       FILE *f;
+       struct blob_attr *certtb[CERT_ATTR_MAX];
+       struct blob_attr *bufpt;
+       struct cert_object *cobj;
+       char filebuf[CERT_BUF_LEN];
+       int ret = 0, pret = 0;
+       int len, pos = 0;
 
        f = fopen(certfile, "r");
        if (!f)
                return 1;
 
-       do {
-               len = fread(&filebuf, 1, CERT_BUF_LEN - 1, f);
-               blob_put_raw(&certbuf, filebuf, len);
-       } while(!feof(f) && !ferror(f));
+       len = fread(&filebuf, 1, CERT_BUF_LEN - 1, f);
+       if (len < 64)
+               return 1;
 
-       ret = ferror(f);
+       ret = ferror(f) || !feof(f);
        fclose(f);
+       if (ret)
+               return 1;
+
+       bufpt = (struct blob_attr *)filebuf;
+       do {
+               pret = blob_parse(bufpt, certtb, cert_policy, CERT_ATTR_MAX);
+               if (pret <= 0)
+                       /* no attributes found */
+                       break;
+
+               if (pos + blob_pad_len(bufpt) > len)
+                       /* blob exceeds filebuffer */
+                       break;
+               else
+                       pos += blob_pad_len(bufpt);
+
+               cobj = calloc(1, sizeof(*cobj));
+               memcpy(cobj->cert, &certtb, sizeof(certtb));
+               list_add_tail(&cobj->list, chain);
+               ret += pret;
+               bufpt = blob_next(bufpt);
+       /* repeat parsing while there is still enough remaining data in buffer */
+       } while(len > pos + sizeof(struct blob_attr));
+
+       return (ret <= 0);
+}
 
+static int cert_append(const char *certfile, const char *sigfile) {
+       FILE *fs;
+       char filebuf[CERT_BUF_LEN];
+       struct blob_buf sigbuf;
+       int len;
+       int ret;
+
+       fs = fopen(sigfile, "r");
+       if (!fs)
+               return 1;
+
+       len = fread(&filebuf, 1, CERT_BUF_LEN - 1, fs);
+       ret = ferror(fs) || !feof(fs) || (len < 64);
+       fclose(fs);
        if (ret)
                return 1;
 
-       blob_parse(certbuf.head, certtb, cert_policy, CERT_ATTR_MAX);
+       blob_buf_init(&sigbuf, 0);
+       blob_put(&sigbuf, CERT_ATTR_SIGNATURE, filebuf, len);
+       ret = write_file(certfile, sigbuf.head, blob_raw_len(sigbuf.head), true);
+       blob_buf_free(&sigbuf);
+       return ret;
+}
+
+static int cert_verify_blob(struct blob_attr *cert[CERT_ATTR_MAX],
+                      const char *pubkeyfile, const char *pubkeydir) {
+       int i;
+       char msgfname[256], sigfname[256];
+       int ret;
+       char tmpdir[] = "/tmp/ucert-XXXXXX";
 
-       return 0;
+       if (mkdtemp(tmpdir) == NULL)
+               return errno;
+
+       snprintf(msgfname, sizeof(msgfname) - 1, "%s/%s", tmpdir, "payload");
+       snprintf(sigfname, sizeof(sigfname) - 1, "%s/%s", tmpdir, "payload.sig");
+
+       for (i = 0; i < CERT_ATTR_MAX; i++) {
+               struct blob_attr *v = cert[i];
+
+               if (!v)
+                       break;
+
+               switch(cert_policy[i].type) {
+               case BLOB_ATTR_BINARY:
+                       write_file(sigfname, blob_data(v), blob_len(v), false);
+                       break;
+               case BLOB_ATTR_NESTED:
+                       write_file(msgfname, blob_data(v), blob_len(v), false);
+                       break;
+               }
+       }
+
+       ret = usign_v(msgfname, pubkeyfile, pubkeydir, sigfname, quiet);
+
+       unlink(msgfname);
+       unlink(sigfname);
+       rmdir(tmpdir);
+
+       return ret;
 }
 
-static int cert_append(const char *certfile, const char *pubkeyfile, const char *sigfile) {
-       fprintf(stderr, "not implemented\n");
-       return 1;
+static int chain_verify(const char *msgfile, const char *pubkeyfile,
+                       const char *pubkeydir, struct list_head *chain) {
+       struct cert_object *cobj;
+       struct blob_attr *containertb[CERT_CT_ATTR_MAX];
+       struct blob_attr *payloadtb[CERT_PL_ATTR_MAX];
+       char tmpdir[] = "/tmp/ucert-XXXXXX";
+       char chainedpubkey[256] = {0};
+       char extsigfile[256] = {0};
+       int ret = 1;
+       int checkmsg = 0;
+
+       if (mkdtemp(tmpdir) == NULL)
+               return errno;
+
+       if (msgfile)
+               checkmsg = -1;
+
+       list_for_each_entry(cobj, chain, list) {
+               /* blob has payload, verify that using signature */
+               if (cobj->cert[CERT_ATTR_PAYLOAD]) {
+                       struct timeval tv;
+                       uint64_t validfrom;
+                       uint64_t expiresat;
+                       uint32_t certtype;
+
+                       ret = cert_verify_blob(cobj->cert, chainedpubkey[0]?chainedpubkey:pubkeyfile, pubkeydir);
+                       if (ret)
+                               goto clean_and_return;
+
+                       blobmsg_parse(cert_cont_policy,
+                                     ARRAY_SIZE(cert_cont_policy),
+                                     containertb,
+                                     blob_data(cobj->cert[CERT_ATTR_PAYLOAD]),
+                                     blob_len(cobj->cert[CERT_ATTR_PAYLOAD]));
+                       if (!containertb[CERT_CT_ATTR_PAYLOAD]) {
+                               ret = 1;
+                               fprintf(stderr, "no ucert in signed payload\n");
+                               goto clean_and_return;
+                       }
+                       blobmsg_parse(cert_payload_policy,
+                                     ARRAY_SIZE(cert_payload_policy),
+                                     payloadtb,
+                                     blobmsg_data(containertb[CERT_CT_ATTR_PAYLOAD]),
+                                     blobmsg_data_len(containertb[CERT_CT_ATTR_PAYLOAD]));
+
+                       if (!payloadtb[CERT_PL_ATTR_CERTTYPE] ||
+                           !payloadtb[CERT_PL_ATTR_VALIDFROMTIME] ||
+                           !payloadtb[CERT_PL_ATTR_EXPIRETIME] ||
+                           !payloadtb[CERT_PL_ATTR_PUBKEY]) {
+                               ret = 1;
+                               fprintf(stderr, "missing mandatory ucert attributes\n");
+                               goto clean_and_return;
+                       }
+                       certtype = blobmsg_get_u32(payloadtb[CERT_PL_ATTR_CERTTYPE]);
+                       validfrom = blobmsg_get_u64(payloadtb[CERT_PL_ATTR_VALIDFROMTIME]);
+                       expiresat = blobmsg_get_u64(payloadtb[CERT_PL_ATTR_EXPIRETIME]);
+
+                       if (certtype != CERTTYPE_AUTH) {
+                               ret = 2;
+                               fprintf(stderr, "wrong certificate type\n");
+                               goto clean_and_return;
+                       }
+
+                       gettimeofday(&tv, NULL);
+                       if (tv.tv_sec < validfrom ||
+                           tv.tv_sec >= expiresat) {
+                               ret = 3;
+                               fprintf(stderr, "certificate expired\n");
+                               goto clean_and_return;
+                       }
+
+                       snprintf(chainedpubkey, sizeof(chainedpubkey) - 1, "%s/%s", tmpdir, "chained-pubkey");
+                       write_file(chainedpubkey,
+                                  blobmsg_data(payloadtb[CERT_PL_ATTR_PUBKEY]),
+                                  blobmsg_data_len(payloadtb[CERT_PL_ATTR_PUBKEY]),
+                                  false);
+               } else {
+               /* blob doesn't have payload, verify message using signature */
+                       if (msgfile) {
+                               snprintf(extsigfile, sizeof(extsigfile) - 1, "%s/%s", tmpdir, "ext-sig");
+                               write_file(extsigfile,
+                                          blob_data(cobj->cert[CERT_ATTR_SIGNATURE]),
+                                          blob_len(cobj->cert[CERT_ATTR_SIGNATURE]),
+                                          false);
+                               checkmsg = ret = usign_v(msgfile,
+                                             chainedpubkey[0]?chainedpubkey:pubkeyfile,
+                                             pubkeydir, extsigfile, quiet);
+                               unlink(extsigfile);
+                       } else {
+                               fprintf(stderr, "stray trailing signature without anything to verify!\n");
+                               ret = 1;
+                       };
+               }
+       }
+
+       if (checkmsg == -1)
+               fprintf(stderr, "missing signature to verify message!\n");
+
+clean_and_return:
+       if (chainedpubkey[0])
+               unlink(chainedpubkey);
+       rmdir(tmpdir);
+       return ret | checkmsg;
+}
+
+static void cert_dump_blob(struct blob_attr *cert[CERT_ATTR_MAX]) {
+       int i;
+
+       for (i = 0; i < CERT_ATTR_MAX; i++) {
+               struct blob_attr *v = cert[i];
+
+               if (!v)
+                       continue;
+
+               switch(cert_policy[i].type) {
+               case BLOB_ATTR_BINARY:
+                       fprintf(stdout, "signature:\n---\n%s---\n", (char *) blob_data(v));
+                       break;
+               case BLOB_ATTR_NESTED:
+                       fprintf(stdout, "payload:\n---\n%s\n---\n", blobmsg_format_json_indent(blob_data(v), false, 0));
+                       break;
+               }
+       }
 }
 
 static int cert_dump(const char *certfile) {
-       struct blob_attr *certtb[CERT_ATTR_MAX];
+       struct cert_object *cobj;
+       static LIST_HEAD(certchain);
+       unsigned int count = 0;
 
-       if (cert_load(certfile, certtb)) {
+       if (cert_load(certfile, &certchain)) {
                fprintf(stderr, "cannot parse cert\n");
                return 1;
        }
 
+       list_for_each_entry(cobj, &certchain, list) {
+               fprintf(stderr, "=== CHAIN ELEMENT %02u ===\n", ++count);
+               cert_dump_blob(cobj->cert);
+               fprintf(stderr, "========================\n");
+       }
+
        return 0;
 }
 
 static int cert_issue(const char *certfile, const char *pubkeyfile, const char *seckeyfile) {
-       fprintf(stderr, "not implemented\n");
-       return 1;
+       struct blob_buf certbuf;
+       struct blob_buf payloadbuf;
+       struct timeval tv;
+       struct stat st;
+       int pklen, siglen;
+       int revoker = 1;
+       void *c;
+       FILE *pkf, *sigf;
+       char pkb[512];
+       char sigb[512];
+       char fname[256], sfname[256];
+       char pkfp[17];
+       char tmpdir[] = "/tmp/ucert-XXXXXX";
+
+       if (stat(certfile, &st) == 0) {
+               fprintf(stderr, "certfile %s exists, won't overwrite.\n", certfile);
+               return -1;
+       }
+
+       pkf = fopen(pubkeyfile, "r");
+       if (!pkf)
+               return -1;
+
+       pklen = fread(pkb, 1, 512, pkf);
+       pkb[pklen] = '\0';
+
+       if (pklen < 32)
+               return -1;
+
+       fclose(pkf);
+
+       if (usign_f_pubkey(pkfp, pubkeyfile))
+               return -1;
+
+       gettimeofday(&tv, NULL);
+
+       if (mkdtemp(tmpdir) == NULL)
+               return errno;
+
+       while (revoker >= 0) {
+               blob_buf_init(&payloadbuf, 0);
+               c = blobmsg_open_table(&payloadbuf, "ucert");
+               blobmsg_add_u32(&payloadbuf, "certtype", revoker?CERTTYPE_REVOKE:CERTTYPE_AUTH);
+               blobmsg_add_u64(&payloadbuf, "validfrom", tv.tv_sec);
+               if (!revoker) {
+                       blobmsg_add_u64(&payloadbuf, "expiresat", tv.tv_sec + 60 * 60 * 24 * 365);
+                       blobmsg_add_string(&payloadbuf, "pubkey", pkb);
+               } else {
+                       blobmsg_add_string(&payloadbuf, "fingerprint", pkfp);
+               }
+
+               blobmsg_close_table(&payloadbuf, c);
+
+               snprintf(fname, sizeof(fname) - 1, "%s/%s", tmpdir, revoker?"revoker":"payload");
+               write_file(fname, blob_data(payloadbuf.head), blob_len(payloadbuf.head), false);
+
+               snprintf(sfname, sizeof(sfname) - 1, "%s/%s", tmpdir, revoker?"revoker.sig":"payload.sig");
+               if (usign_s(fname, seckeyfile, sfname, quiet))
+                       return 1;
+
+               sigf = fopen(sfname, "r");
+               if (!sigf)
+                       return 1;
+
+               siglen = fread(sigb, 1, 1024, sigf);
+               if (siglen < 1)
+                       return 1;
+
+               sigb[siglen] = '\0';
+               fclose(sigf);
+
+               unlink(fname);
+               unlink(sfname);
+
+               blob_buf_init(&certbuf, 0);
+               blob_put(&certbuf, CERT_ATTR_SIGNATURE, sigb, siglen);
+               blob_put(&certbuf, CERT_ATTR_PAYLOAD, blob_data(payloadbuf.head), blob_len(payloadbuf.head));
+               snprintf(fname, sizeof(fname) - 1, "%s%s", certfile, revoker?".revoke":"");
+               write_file(fname, certbuf.head, blob_raw_len(certbuf.head), false);
+               blob_buf_free(&certbuf);
+               blob_buf_free(&payloadbuf);
+
+               revoker--;
+       }
+
+       rmdir(tmpdir);
+
+       return 0;
 }
 
-static int cert_process_revoker(const char *certfile) {
-       fprintf(stderr, "not implemented\n");
-       return 1;
+static int cert_process_revoker(const char *certfile, const char *pubkeydir) {
+       static LIST_HEAD(certchain);
+       struct cert_object *cobj;
+       struct blob_attr *containertb[CERT_CT_ATTR_MAX];
+       struct blob_attr *payloadtb[CERT_PL_ATTR_MAX];
+       struct stat st;
+       struct timeval tv;
+       uint64_t validfrom;
+       uint32_t certtype;
+       char *fingerprint;
+       char rfname[512];
+
+       int ret;
+
+       if (cert_load(certfile, &certchain)) {
+               fprintf(stderr, "cannot parse cert\n");
+               return 1;
+       }
+
+       list_for_each_entry(cobj, &certchain, list) {
+               /* blob has payload, verify that using signature */
+               if (!cobj->cert[CERT_ATTR_PAYLOAD])
+                       return 2;
+               ret = cert_verify_blob(cobj->cert, NULL, pubkeydir);
+               if (ret)
+                       return ret;
+
+               blobmsg_parse(cert_cont_policy,
+                             ARRAY_SIZE(cert_cont_policy),
+                             containertb,
+                             blob_data(cobj->cert[CERT_ATTR_PAYLOAD]),
+                             blob_len(cobj->cert[CERT_ATTR_PAYLOAD]));
+               if (!containertb[CERT_CT_ATTR_PAYLOAD]) {
+                       fprintf(stderr, "no ucert in signed payload\n");
+                       return 2;
+               }
+
+               blobmsg_parse(cert_payload_policy,
+                             ARRAY_SIZE(cert_payload_policy),
+                             payloadtb,
+                             blobmsg_data(containertb[CERT_CT_ATTR_PAYLOAD]),
+                             blobmsg_data_len(containertb[CERT_CT_ATTR_PAYLOAD]));
+
+               if (!payloadtb[CERT_PL_ATTR_CERTTYPE] ||
+                   !payloadtb[CERT_PL_ATTR_VALIDFROMTIME] ||
+                   !payloadtb[CERT_PL_ATTR_KEY_FINGERPRINT]) {
+                               fprintf(stderr, "missing mandatory ucert attributes\n");
+                               return 2;
+                       }
+
+               certtype = blobmsg_get_u32(payloadtb[CERT_PL_ATTR_CERTTYPE]);
+               validfrom = blobmsg_get_u64(payloadtb[CERT_PL_ATTR_VALIDFROMTIME]);
+               fingerprint = blobmsg_get_string(payloadtb[CERT_PL_ATTR_KEY_FINGERPRINT]);
+
+               if (certtype != CERTTYPE_REVOKE) {
+                       fprintf(stderr, "wrong certificate type\n");
+                       return 2;
+               }
+
+               gettimeofday(&tv, NULL);
+               if (tv.tv_sec < validfrom) {
+                       return 3;
+               }
+
+               snprintf(rfname, sizeof(rfname)-1, "%s/%s", pubkeydir, fingerprint);
+               /* check if entry in pubkeydir exists */
+               if (stat(rfname, &st) == 0) {
+                       char tml[64] = {0};
+                       /* if it's an existing revoker deadlink we are happy */
+                       if (readlink(rfname, tml, sizeof(tml)) > 0 &&
+                           !strcmp(tml, ".revoked.")) {
+                               if (!quiet)
+                                       fprintf(stdout, "existing revoker deadlink for key %s\n", fingerprint);
+                               continue;
+                       };
+
+                       /* remove any other entry */
+                       if (unlink(rfname))
+                               return -1;
+               }
+
+               ret = symlink(".revoked.", rfname);
+               if (ret)
+                       return ret;
+
+               if (!quiet)
+                       fprintf(stdout, "created revoker deadlink for key %s\n", fingerprint);
+       };
+
+       return ret;
 }
 
 static int cert_verify(const char *certfile, const char *pubkeyfile, const char *pubkeydir, const char *msgfile) {
-       fprintf(stderr, "not implemented\n");
-       return 1;
+       static LIST_HEAD(certchain);
+
+       if (cert_load(certfile, &certchain)) {
+               fprintf(stderr, "cannot parse cert\n");
+               return 1;
+       }
+
+       return chain_verify(msgfile, pubkeyfile, pubkeydir, &certchain);
 }
 
 static int usage(const char *cmd)
@@ -148,11 +562,11 @@ static int usage(const char *cmd)
        fprintf(stderr,
                "Usage: %s <command> <options>\n"
                "Commands:\n"
-               "  -A:                  append (needs -c and -p and/or -x)\n"
-               "  -D:                  dump\n"
+               "  -A:                  append signature (needs -c and -x)\n"
+               "  -D:                  dump (needs -c)\n"
                "  -I:                  issue cert and revoker (needs -c and -p and -s)\n"
-               "  -R:                  process revoker certificate (needs -c)\n"
-               "  -V:                  verify (needs -c and -p|-P)\n"
+               "  -R:                  process revoker certificate (needs -c and -P)\n"
+               "  -V:                  verify (needs -c and -p|-P, may have -m)\n"
                "Options:\n"
                "  -c <file>:           certificate file\n"
                "  -m <file>:           message file (verify only)\n"
@@ -205,12 +619,12 @@ int main(int argc, char *argv[]) {
                case 'P':
                        pubkeydir = optarg;
                        break;
-               case 's':
-                       seckeyfile = optarg;
-                       break;
                case 'q':
                        quiet = true;
                        break;
+               case 's':
+                       seckeyfile = optarg;
+                       break;
                case 'x':
                        sigfile = optarg;
                        break;
@@ -221,8 +635,8 @@ int main(int argc, char *argv[]) {
 
        switch (cmd) {
        case CMD_APPEND:
-               if (certfile && (pubkeyfile || sigfile))
-                       return cert_append(certfile, pubkeyfile, sigfile);
+               if (certfile && sigfile)
+                       return cert_append(certfile, sigfile);
                else
                        return usage(argv[0]);
        case CMD_DUMP:
@@ -236,8 +650,8 @@ int main(int argc, char *argv[]) {
                else
                        return usage(argv[0]);
        case CMD_REVOKE:
-               if (certfile)
-                       return cert_process_revoker(certfile);
+               if (certfile && pubkeydir)
+                       return cert_process_revoker(certfile, pubkeydir);
                else
                        return usage(argv[0]);
        case CMD_VERIFY: