security checking, handle PROCESS command

diff --git a/Makefile b/Makefile
new file mode 100644 (file)
index 0000000..79d03c2
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,4 @@
+CFLAGS = -Wall
+LDFLAGS = -lident
+
+dspam-spamd: dspam-spamd.c

diff --git a/dspam-spamd.c b/dspam-spamd.c
index 4f3cb6f39774cd3cca3d80fd6ff15da30903784b..5d4ebe8543e33481c130eb2f2912bb47a6eac02e 100644 (file)
--- a/dspam-spamd.c
+++ b/dspam-spamd.c
@@ -7,6 +7,9 @@
 #include <signal.h>
 #include <sysexits.h>
 #include <sys/wait.h>
+#include <ident.h>
+#include <sys/socket.h>
+#include <errno.h>
 
 #define ERROR(code,descr) do {                                         \
                printf("SPAMD/1.1 %d %s\r\n", code, descr);             \
@@ -27,8 +30,28 @@ int main() {
        int dspam_in[2], dspam_out[2], dspam_err[2];
        int status;
        char *lflf, *crlfcrlf;
+       struct sockaddr_in addr;
+       socklen_t addrlen = sizeof(addr);
+       char *id;
+
+       if (getpeername(0, (struct sockaddr*)&addr, &addrlen)) {
+               if (errno == ENOTSOCK) {
+                       struct passwd *p = getpwuid(getuid());
+                       if (p) {
+                               id = p->pw_name;
+                               goto cont_after_permcheck;
+                       }
+                       ERROR(EX_NOPERM, "couldn't look up your username");
+               }
+               ERROR(EX_NOPERM, "couldn't look up your host address");
+       }
+       if (addr.sin_family != AF_INET || addr.sin_addr.s_addr != htonl(0x7f000001))
+               ERROR(EX_NOPERM, "not connected from localhost");
+       id = ident_id(0, 30);
+       if (!id)
+               ERROR(EX_NOPERM, "permission denied, run an ident server");
 
-
+ cont_after_permcheck:
        signal(SIGPIPE, SIG_IGN);
        /* read command */
        fgets(buf, sizeof(buf), stdin);
@@ -37,10 +60,10 @@ int main() {
                ERROR(EX_PROTOCOL, "line too long");
 
        if (sscanf(buf, "%s SPAMC/%s", cmd, version) != 2) {
-               ERROR(EX_PROTOCOL, "invalid input line");
+               ERROR(EX_PROTOCOL, "invalid input line (cmd)");
        }
-       if (strcmp(cmd, "REPORT") != 0)
-               ERROR(EX_PROTOCOL, "can only handle REPORT");
+       if (strcmp(cmd, "REPORT") && strcmp(cmd, "PROCESS"))
+               ERROR(EX_PROTOCOL, "can only handle REPORT and PROCESS");
        if (strcmp(version, "1.2") != 0)
                ERROR(EX_PROTOCOL, "can only handle version 1.2");
 
@@ -51,7 +74,10 @@ int main() {
                ERROR(EX_PROTOCOL, "line too long");
 
        if (sscanf(buf, "User: %s", user) != 1)
-               ERROR(EX_PROTOCOL, "invalid input line");
+               ERROR(EX_PROTOCOL, "invalid input line (user)");
+
+       if (strcmp(id, user) && strcmp(id, "root") && strcmp(id, "Debian-exim"))
+               ERROR(EX_NOPERM, "you can only check spam for yourself unless priviledged");
 
        struct passwd *ps;
        ps = getpwnam(user);
@@ -67,7 +93,7 @@ int main() {
                ERROR(EX_PROTOCOL, "line too long");
 
        if (sscanf(buf, "Content-length: %d", &length) != 1)
-               ERROR(EX_PROTOCOL, "invalid input line");
+               ERROR(EX_PROTOCOL, "invalid input line (length)");
 
        /* now an empty line */
        fgets(buf, sizeof(buf), stdin);
@@ -145,7 +171,7 @@ int main() {
        }
 
        /* rely on the fact that dspam doesn't dump a lot of data on stderr */
-       if (length = fread(buf, 1, sizeof(buf), fdspam_err))
+       if ((length = fread(buf, 1, sizeof(buf), fdspam_err)))
                ERROR(EX_TEMPFAIL, "dspam printed something to stderr");
 
        status = 0;
@@ -157,58 +183,66 @@ int main() {
         * The only valid command right now is REPORT so we
         * extract the lines dspam added to the header first. */
 
-       /* null terminate message */
-       processed[readlen] = '\0';
-       lflf = strstr(processed, "\n\n");
-       crlfcrlf = strstr(processed, "\r\n\r\n");
-       if (lflf) *lflf='\0';
-       if (crlfcrlf) *crlfcrlf='\0';
-       if (!lflf && !crlfcrlf)
-               ERROR(EX_TEMPFAIL, "dspam failed to return a proper message");
-
-       /* second part of dirty trick */
-       tmp2 = processed;
-
-       while (tmp2 && (tmp = strstr(tmp2, "\nX-DSPAM"))) {
-               tmp++;
-               tmp2 = strchr(tmp, '\n');
-               if (tmp2) *tmp2 = '\0';
-               strcpy(dspamres, tmp);
-               dspamres += strlen(tmp);
-               *dspamres = '\n';
-               dspamres++;
-               if (tmp2) *tmp2 = '\n';
+       /* null terminate message. Yes, due to trick +1 is correct! */
+       processed[readlen+1] = '\0';
+
+       if (strcmp(cmd, "REPORT") == 0) {
+               lflf = strstr(processed, "\n\n");
+               crlfcrlf = strstr(processed, "\r\n\r\n");
+               if (lflf) *lflf='\0';
+               if (crlfcrlf) *crlfcrlf='\0';
+               if (!lflf && !crlfcrlf)
+                       ERROR(EX_TEMPFAIL, "dspam failed to return a proper message");
+
+               /* second part of dirty trick */
+               tmp2 = processed;
+
+               while (tmp2 && (tmp = strstr(tmp2, "\nX-DSPAM"))) {
+                       tmp++;
+                       tmp2 = strchr(tmp, '\n');
+                       if (tmp2) *tmp2 = '\0';
+                       strcpy(dspamres, tmp);
+                       dspamres += strlen(tmp);
+                       *dspamres = '\n';
+                       dspamres++;
+                       if (tmp2) *tmp2 = '\n';
+               }
+               *dspamres = '\0';
+
+               /* now we have everything dspam gave us */
+               char *res = strstr(dspamresult, "X-DSPAM-Result: ");
+               if (!res)
+                       ERROR(EX_TEMPFAIL, "no dspam result!");
+
+               char spamtag[20];
+               strncpy(spamtag, res + strlen("X-DSPAM-Result: "), sizeof(spamtag));
+               int i;
+               for (i = 0; i < 20; i++)
+                       if (spamtag[i] == '\n') spamtag[i] = '\0';
+               spamtag[19] = '\0';
+
+               char *conf = strstr(dspamresult, "X-DSPAM-Confidence: ");
+               if (!conf)
+                       ERROR(EX_TEMPFAIL, "no dspam confidence!");
+               float confidence;
+               if (sscanf(conf, "X-DSPAM-Confidence: %f", &confidence) != 1)
+                       ERROR(EX_TEMPFAIL, "could not parse dspam confidence");
+               confidence *= 10;
+
+               int isspam = strcasecmp(spamtag,"Spam")==0;
+               if (!isspam) confidence = 0;
+               printf("SPAMD/1.1 0 EX_OK\r\n");
+               printf("Spam: %s", isspam?"True":"False");
+               printf(" ; %f / 0\r\n\r\n", confidence);
+
+               printf("%s", dspamresult);
+       } else {
+               /* PROCESS */
+               printf("SPAMD/1.1 0 EX_OK\r\n");
+               printf("Content-length: %d\r\n", readlen);
+               printf("\r\n");
+               fwrite(processed+1, 1, readlen, stdout);
        }
-       *dspamres = '\0';
-
-       /* now we have everything dspam gave us */
-       char *res = strstr(dspamresult, "X-DSPAM-Result: ");
-       if (!res)
-               ERROR(EX_TEMPFAIL, "no dspam result!");
-
-       char spamtag[20];
-       strncpy(spamtag, res + strlen("X-DSPAM-Result: "), sizeof(spamtag));
-       int i;
-       for (i = 0; i < 20; i++)
-               if (spamtag[i] == '\n') spamtag[i] = '\0';
-       spamtag[19] = '\0';
-
-       char *conf = strstr(dspamresult, "X-DSPAM-Confidence: ");
-       if (!conf)
-               ERROR(EX_TEMPFAIL, "no dspam confidence!");
-       float confidence;
-       if (sscanf(conf, "X-DSPAM-Confidence: %f", &confidence) != 1)
-               ERROR(EX_TEMPFAIL, "could not parse dspam confidence");
-       confidence *= 10;
-
-       int isspam = strcasecmp(spamtag,"Spam")==0;
-       if (!isspam) confidence = 0;
-       printf("SPAMD/1.1 0 EX_OK\r\n");
-       printf("Spam: %s", isspam?"True":"False");
-       printf(" ; %f / 0\r\n\r\n", confidence);
-
-       printf("%s", dspamresult);
-
        /* always return ok status to (x)inetd */
        return 0;
 }