From ead4ec3089b97eda1b438da248caf76f169345ad Mon Sep 17 00:00:00 2001 From: netblue30 Date: Sat, 18 Nov 2017 08:39:02 -0500 Subject: netfilter template support --- src/firejail/netfilter.c | 13 ++++- src/firejail/usage.c | 2 +- src/fnetfilter/main.c | 144 +++++++++++++++++++++++++++++++++++++++-------- src/man/firejail.txt | 23 +++++++- 4 files changed, 153 insertions(+), 29 deletions(-) (limited to 'src') 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 #include - 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 -- cgit v1.2.3-54-g00ecf