1 files changed, 219 insertions, 0 deletions

diff --git a/src/fseccomp/protocol.c b/src/fseccomp/protocol.c
new file mode 100644
index 000000000..38c5f9d88
--- /dev/null
+++ b/src/fseccomp/protocol.c
@@ -0,0 +1,219 @@
+/*
+ * Copyright (C) 2014-2016 Firejail Authors
+ *
+ * This file is part of firejail project
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+/*
+        struct sock_filter filter[] = {
+                VALIDATE_ARCHITECTURE,
+                EXAMINE_SYSCALL,
+                ONLY(SYS_socket),
+                EXAMINE_ARGUMENT(0), // allow only AF_INET and AF_INET6, drop everything else
+                WHITELIST(AF_INET),
+                WHITELIST(AF_INET6),
+                WHITELIST(AF_PACKET),
+                RETURN_ERRNO(ENOTSUP)
+        };
+        struct sock_fprog prog = {
+                .len = (unsigned short)(sizeof(filter) / sizeof(filter[0])),
+                .filter = filter,
+        };
+
+
+        if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
+                perror("prctl(NO_NEW_PRIVS)");
+                return 1;
+        }
+        if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog)) {
+                perror("prctl");
+                return 1;
+        }
+*/
+
+#include "fseccomp.h"
+#include "../include/seccomp.h"
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+
+static char *protocol[] = {
+        "unix",
+        "inet",
+        "inet6",
+        "netlink",
+        "packet",
+        NULL
+};
+
+static struct sock_filter protocol_filter_command[] = {
+        WHITELIST(AF_UNIX),
+        WHITELIST(AF_INET),
+        WHITELIST(AF_INET6),
+        WHITELIST(AF_NETLINK),
+        WHITELIST(AF_PACKET)
+};
+// Note: protocol[] and protocol_filter_command are synchronized
+
+// command length
+struct sock_filter whitelist[] = {
+        WHITELIST(AF_UNIX)
+};
+unsigned whitelist_len = sizeof(whitelist) / sizeof(struct sock_filter);
+
+static struct sock_filter *find_protocol_domain(const char *p) {
+        int i = 0;
+        while (protocol[i] != NULL) {
+                if (strcmp(protocol[i], p) == 0)
+                        return &protocol_filter_command[i * whitelist_len];
+                i++;
+        }
+
+        return NULL;
+}       
+
+
+void protocol_print(void) {
+#ifndef SYS_socket
+        fprintf(stderr, "Warning fseccomp: firejail --protocol not supported on this platform\n");
+        return;
+#endif
+
+        int i = 0;
+        while (protocol[i] != NULL) {
+                printf("%s, ", protocol[i]);
+                i++;
+        }
+        printf("\n");
+}
+
+// install protocol filter
+void protocol_build_filter(const char *prlist, const char *fname) {
+        assert(prlist);
+        assert(fname);
+
+#ifndef SYS_socket
+        fprintf(stderr, "Warning: --protocol not supported on this platform\n");
+        return;
+#else
+        // build the filter
+        struct sock_filter filter[32];  // big enough
+        memset(&filter[0], 0, sizeof(filter));
+        uint8_t *ptr = (uint8_t *) &filter[0];
+        
+        // header
+        struct sock_filter filter_start[] = {
+                VALIDATE_ARCHITECTURE,
+                EXAMINE_SYSCALL,
+                ONLY(SYS_socket),
+                EXAMINE_ARGUMENT(0)
+        };
+        memcpy(ptr, &filter_start[0], sizeof(filter_start));
+        ptr += sizeof(filter_start);
+
+#if 0
+printf("entries %u\n", (unsigned) (sizeof(filter_start) / sizeof(struct sock_filter)));
+{
+        unsigned j;
+        unsigned char *ptr2 = (unsigned char *) &filter[0];
+        for (j = 0; j < sizeof(filter); j++, ptr2++) {
+                if ((j % (sizeof(struct sock_filter))) == 0)
+                        printf("\n%u: ", 1 + (unsigned) (j / (sizeof(struct sock_filter))));
+                printf("%02x, ", (*ptr2) & 0xff);
+        }
+        printf("\n");
+}
+printf("whitelist_len %u, struct sock_filter len %u\n", whitelist_len, (unsigned) sizeof(struct sock_filter));
+#endif
+
+
+        // parse list and add commands
+        char *tmplist = strdup(prlist);
+        if (!tmplist)
+                errExit("strdup");
+        char *token = strtok(tmplist, ",");
+        if (!token)
+                errExit("strtok");
+                
+        while (token) {
+                struct sock_filter *domain = find_protocol_domain(token);
+                if (domain == NULL) {
+                        fprintf(stderr, "Error fseccomp: %s is not a valid protocol\n", token);
+                        exit(1);
+                }
+                memcpy(ptr, domain, whitelist_len * sizeof(struct sock_filter));
+                ptr += whitelist_len * sizeof(struct sock_filter);
+                token = strtok(NULL, ",");
+
+#if 0
+printf("entries %u\n",  (unsigned) ((uint64_t) ptr - (uint64_t) (filter)) / (unsigned) sizeof(struct sock_filter));
+{
+        unsigned j;
+        unsigned char *ptr2 = (unsigned char *) &filter[0];
+        for (j = 0; j < sizeof(filter); j++, ptr2++) {
+                if ((j % (sizeof(struct sock_filter))) == 0)
+                        printf("\n%u: ", 1 + (unsigned) (j / (sizeof(struct sock_filter))));
+                printf("%02x, ", (*ptr2) & 0xff);
+        }
+        printf("\n");
+}
+#endif
+
+
+        }       
+        free(tmplist);
+
+        // add end of filter
+        struct sock_filter filter_end[] = {
+                RETURN_ERRNO(ENOTSUP)
+        };
+        memcpy(ptr, &filter_end[0], sizeof(filter_end));
+        ptr += sizeof(filter_end);
+
+#if 0
+printf("entries %u\n",  (unsigned) ((uint64_t) ptr - (uint64_t) (filter)) / (unsigned) sizeof(struct sock_filter));
+{
+        unsigned j;
+        unsigned char *ptr2 = (unsigned char *) &filter[0];
+        for (j = 0; j < sizeof(filter); j++, ptr2++) {
+                if ((j % (sizeof(struct sock_filter))) == 0)
+                        printf("\n%u: ", 1 + (unsigned) (j / (sizeof(struct sock_filter))));
+                printf("%02x, ", (*ptr2) & 0xff);
+        }
+        printf("\n");
+}
+#endif  
+        // save filter to file
+        int dst = open(fname, O_CREAT|O_WRONLY|O_TRUNC, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+        if (dst < 0) {
+                fprintf(stderr, "Error fseccomp: cannot open %s file\n", fname);
+                exit(1);
+        }
+        
+        int size = (int) ((uintptr_t) ptr - (uintptr_t) (filter));
+        int written = 0;
+        while (written < size) {
+                int rv = write(dst, (unsigned char *) filter + written, size - written);
+                if (rv == -1) {
+                        fprintf(stderr, "Error fseccomp: cannot write %s file\n", fname);
+                        exit(1);
+                }
+                written += rv;
+        }
+        close(dst);
+#endif // SYS_socket    
+}