netfilter template support

4 files changed, 153 insertions, 29 deletions

diff --git a/src/firejail/netfilter.c b/src/firejail/netfilter.c
index e1d0edd01..dd4009a2e 100644
--- a/src/firejail/netfilter.c
+++ b/src/firejail/netfilter.c
@@ -24,7 +24,6 @@
 #include <sys/wait.h>
 #include <fcntl.h>
 
-
 void check_netfilter_file(const char *fname) {
         EUID_ASSERT();
 
@@ -44,7 +43,6 @@ void check_netfilter_file(const char *fname) {
         free(tmp);
 }
 
-
 void netfilter(const char *fname) {
         // find iptables command
         struct stat s;
@@ -150,6 +148,16 @@ void netfilter_print(pid_t pid, int ipv6) {
         }
         free(comm);
 
+        // check privileges for non-root users
+        uid_t uid = getuid();
+        if (uid != 0) {
+                uid_t sandbox_uid = pid_get_uid(pid);
+                if (uid != sandbox_uid) {
+                        fprintf(stderr, "Error: permission is denied to join a sandbox created by a different user.\n");
+                        exit(1);
+                }
+        }
+
         // check network namespace
         char *name;
         if (asprintf(&name, "/run/firejail/network/%d-netmap", pid) == -1)
@@ -196,4 +204,3 @@ void netfilter_print(pid_t pid, int ipv6) {
 
         sbox_run(SBOX_ROOT | SBOX_CAPS_NETWORK | SBOX_SECCOMP, 2, iptables, "-vL");
 }
-
diff --git a/src/firejail/usage.c b/src/firejail/usage.c
index f1581e847..89ea4ccca 100644
--- a/src/firejail/usage.c
+++ b/src/firejail/usage.c
@@ -122,7 +122,7 @@ void usage(void) {
         printf("    --net=ethernet_interface - enable network namespaces and connect to this\n");
         printf("\tEthernet interface.\n");
         printf("    --net=none - enable a new, unconnected network namespace.\n");
-        printf("    --netfilter[=filename] - enable firewall.\n");
+        printf("    --netfilter[=filename,arg1,arg2,arg3 ...] - enable firewall.\n");
         printf("    --netfilter.print=name|pid - print the firewall.\n");
         printf("    --netfilter6=filename - enable IPv6 firewall.\n");
         printf("    --netfilter6.print=name|pid - print the IPv6 firewall.\n");
diff --git a/src/fnetfilter/main.c b/src/fnetfilter/main.c
index 67ab31832..723c1ac32 100644
--- a/src/fnetfilter/main.c
+++ b/src/fnetfilter/main.c
@@ -20,8 +20,12 @@
 #include "../include/common.h"
 
 #define MAXBUF 4098
+#define MAXARGS 16
+static char *args[MAXARGS] = {0};
+static int argcnt = 0;
 int arg_quiet = 0;
 
+
 static char *default_filter =
 "*filter\n"
 ":INPUT DROP [0:0]\n"
@@ -29,7 +33,7 @@ static char *default_filter =
 ":OUTPUT ACCEPT [0:0]\n"
 "-A INPUT -i lo -j ACCEPT\n"
 "-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT\n"
-"# echo replay is handled by -m state RELATED/ESTABLISHED below\n"
+"# echo replay is handled by -m state RELATED/ESTABLISHED above\n"
 "#-A INPUT -p icmp --icmp-type echo-reply -j ACCEPT\n"
 "-A INPUT -p icmp --icmp-type destination-unreachable -j ACCEPT\n"
 "-A INPUT -p icmp --icmp-type time-exceeded -j ACCEPT\n"
@@ -46,6 +50,111 @@ static void usage(void) {
         printf("\tfnetfilter netfilter-command destination-file\n");
 }
 
+
+static void copy(const char *src, const char *dest) {
+        FILE *fp1 = fopen(src, "r");
+        if (!fp1) {
+                fprintf(stderr, "Error fnetfilter: cannot open %s\n", src);
+                exit(1);
+        }
+
+        FILE *fp2 = fopen(dest, "w");
+        if (!fp2) {
+                fprintf(stderr, "Error fnetfilter: cannot open %s\n", dest);
+                exit(1);
+        }
+
+        char buf[MAXBUF];
+        while (fgets(buf, MAXBUF, fp1))
+                fprintf(fp2, "%s", buf);
+
+        fclose(fp1);
+        fclose(fp2);
+}
+
+static void process_template(char *src, const char *dest) {
+        char *arg_start = strchr(src, ',');
+        assert(arg_start);
+        *arg_start = '\0';
+        arg_start++;
+        if (*arg_start == '\0') {
+                fprintf(stderr, "Error fnetfilter: you need to provide at least on argument\n");
+                exit(1);
+        }
+
+        // extract the arguments from command line
+        char *token = strtok(arg_start, ",");
+        while (token) {
+                // look for abnormal things
+                int len = strlen(token);
+                if (strcspn(token, "\\&!?\"'<>%^(){};,*[]") != (size_t)len) {
+                        fprintf(stderr, "Error fnetfilter: invalid argument in netfilter command\n");
+                        exit(1);
+                }
+                args[argcnt] = token;
+                argcnt++;
+                token = strtok(NULL, ",");
+        }
+#if 0
+{
+printf("argcnt %d\n", argcnt);
+int i;
+for (i = 0; i < argcnt; i++)
+        printf("%s\n", args[i]);
+}
+#endif
+
+        // open the files
+        FILE *fp1 = fopen(src, "r");
+        if (!fp1) {
+                fprintf(stderr, "Error fnetfilter: cannot open %s\n", src);
+                exit(1);
+        }
+
+        FILE *fp2 = fopen(dest, "w");
+        if (!fp2) {
+                fprintf(stderr, "Error fnetfilter: cannot open %s\n", dest);
+                exit(1);
+        }
+
+        int line = 0;
+        char buf[MAXBUF];
+        while (fgets(buf, MAXBUF, fp1)) {
+                line++;
+                char *ptr = buf;
+                while (*ptr != '\0') {
+                        if (*ptr != '$')
+                                fputc(*ptr, fp2);
+                        else {
+                                // parsing
+                                int index = 0;
+                                int rv = sscanf(ptr, "$ARG%u", &index) ;
+                                if (rv != 1) {
+                                        fprintf(stderr, "Error fnetfilter: invalid template argument on line %d\n", line);
+                                        exit(1);
+                                }
+
+                                // print argument
+                                if (index < 1 || index > argcnt) {
+                                        fprintf(stderr, "Error fnetfilter: $ARG%d on line %d was not defined\n", index, line);
+                                        exit(1);
+                                }
+                                fprintf(fp2, "%s", args[index - 1]);
+
+                                // march to the end of argument
+                                ptr += 4;
+                                while (isdigit(*ptr))
+                                        ptr++;
+                                ptr--;
+                        }
+                        ptr++;
+                }
+        }
+
+        fclose(fp1);
+        fclose(fp2);
+}
+
 int main(int argc, char **argv) {
 #if 0
 {
@@ -61,7 +170,7 @@ printf("\n");
         if (quiet && strcmp(quiet, "yes") == 0)
                 arg_quiet = 1;
 
-        if (strcmp(argv[1], "-h") == 0 || strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") ==0) {
+        if (argc > 1 && (strcmp(argv[1], "-h") == 0 || strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") ==0)) {
                 usage();
                 return 0;
         }
@@ -75,6 +184,12 @@ printf("\n");
         char *command = (argc == 3)? argv[1]: NULL;     
 //printf("command %s\n", command);
 //printf("destfile %s\n", destfile);
+        // destfile is a real filename
+        int len = strlen(destfile);
+        if (strcspn(destfile, "\\&!?\"'<>%^(){};,*[]") != (size_t)len) {
+                fprintf(stderr, "Error fnetfilter: invalid destination file in netfilter command\n");
+                exit(1);
+        }
 
         // handle default config (command = NULL, destfile)
         if (command == NULL) {
@@ -88,28 +203,11 @@ printf("\n");
                 fclose(fp);
         }
         else {
-                // copy the file
-                FILE *fp1 = fopen(command, "r");
-                if (!fp1) {
-                        fprintf(stderr, "Error fnetfilter: cannot open %s\n", command);
-                        exit(1);
-                }
-
-                FILE *fp2 = fopen(destfile, "w");
-                if (!fp2) {
-                        fprintf(stderr, "Error fnetfilter: cannot open %s\n", destfile);
-                        exit(1);
-                }
-                
-                char buf[MAXBUF];
-                while (fgets(buf, MAXBUF, fp1))
-                        fprintf(fp2, "%s", buf);
-
-                fclose(fp1);
-                fclose(fp2);
+                if (strrchr(command, ','))
+                        process_template(command, destfile);
+                else
+                        copy(command, destfile);
         }
         
-
-printf("fnetfilter running\n");
         return 0;
 }
diff --git a/src/man/firejail.txt b/src/man/firejail.txt
index bf27c07ad..d9000fd5e 100644
--- a/src/man/firejail.txt
+++ b/src/man/firejail.txt
@@ -937,13 +937,32 @@ is a desktop client firewall that disable access to local network. Example:
 $ firejail --netfilter=/etc/firejail/nolocal.net \\
 .br
 --net=eth0 firefox
+
+
+
+
+.TP
+\fB\-\-netfilter=filename,arg1,arg2,arg3 ...
+This is the template version of the previous command. $ARG1, $ARG2, $ARG3 ... in the firewall script
+are replaced with arg1, arg2, arg3 ... passed on the command line. Up to 16 arguments are supported.
+Example:
+.br
+
+.br
+$ firejail --net=eth0 --ip=192.168.1.105 \\
+.br
+--netfilter=/etc/firejail/tcpserver.net,5001 server-program
+.br
+
+
+
 .TP
 \fB\-\-netfilter.print=name|pid
 Print the firewall installed in the sandbox specified by name or PID. Example:
 .br
 
 .br
-$ firejail --net=browser --net=eth0 --netfilter firefox &
+$ firejail --name=browser --net=eth0 --netfilter firefox &
 .br
 $ firejail --netfilter.print=browser
 
@@ -959,7 +978,7 @@ Print the IPv6 firewall installed in the sandbox specified by name or PID. Examp
 .br
 
 .br
-$ firejail --net=browser --net=eth0 --netfilter firefox &
+$ firejail --name=browser --net=eth0 --netfilter firefox &
 .br
 $ firejail --netfilter6.print=browser