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mwan3: use helper library for mwan3track
Rather than using a special mwan3 user to manage mwan3track's tracking packets, this commit implements a small helper library to bind to device and to set a fwmark so that the tracking packets can be routed out of the correct interface. This provides a consistent method for binding to a device rather than relying on various packages potentially buggy implementations. For example: #8139 and #12836 This helper issue also allows for more tracking methods to be added even if they do not have a command line option to bind to device, such as iperf3 (eg #13050). Signed-off-by: Aaron Goodman <aaronjg@stanford.edu>lilik-openwrt-22.03
Aaron Goodman
4 years ago
5 changed files with 312 additions and 121 deletions
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+8 -2net/mwan3/Makefile
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+26 -1net/mwan3/files/lib/mwan3/common.sh
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+2 -91net/mwan3/files/lib/mwan3/mwan3.sh
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+21 -27net/mwan3/files/usr/sbin/mwan3track
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+255 -0net/mwan3/src/sockopt_wrap.c
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net/mwan3/Makefile
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+ 26
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net/mwan3/files/lib/mwan3/common.sh
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+ 2
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net/mwan3/files/lib/mwan3/mwan3.sh
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net/mwan3/files/usr/sbin/mwan3track
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net/mwan3/src/sockopt_wrap.c
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| @ -0,0 +1,255 @@ | |||
| // SPDX-License-Identifier: GPL-2.0 | |||
| /* | |||
| * Copyright (C) 2020 Aaron Goodman <aaronjg@alumni.stanford.edu>. All Rights Reserved. | |||
| */ | |||
| /* | |||
| * sockopt_wrap.c provides a shared library that intercepts syscalls to various | |||
| * networking functions to bind the sockets a source IP address and network device | |||
| * and to set the firewall mark on otugoing packets. Parameters are set using the | |||
| * DEVICE, SRCIP, FWMARK environment variables. | |||
| * | |||
| * Additionally the FAMILY environment variable can be set to either 'ipv4' or | |||
| * 'ipv6' to cause sockets opened with ipv6 or ipv4 to fail, respectively. | |||
| * | |||
| * Each environment variable is optional, and if not set, the library will not | |||
| * enforce the particular parameter. | |||
| */ | |||
| #define _GNU_SOURCE | |||
| #include <dlfcn.h> | |||
| #include <stdlib.h> | |||
| #include <stdio.h> | |||
| #include <string.h> | |||
| #include <arpa/inet.h> | |||
| #include <net/ethernet.h> | |||
| #include <linux/if_packet.h> | |||
| #include <net/if.h> | |||
| static int (*next_socket)(int domain, int type, int protocol); | |||
| static int (*next_setsockopt)(int sockfd, int level, int optname, | |||
| const void *optval, socklen_t optlen); | |||
| static int (*next_bind)(int sockfd, const struct sockaddr *addr, socklen_t addrlen); | |||
| static int (*next_close)(int fd); | |||
| static ssize_t (*next_send)(int sockfd, const void *buf, size_t len, int flags); | |||
| static ssize_t (*next_sendto)(int sockfd, const void *buf, size_t len, int flags, | |||
| const struct sockaddr *dest_addr, socklen_t addrlen); | |||
| static ssize_t (*next_sendmsg)(int sockfd, const struct msghdr *msg, int flags); | |||
| static int (*next_connect)(int sockfd, const struct sockaddr *addr, | |||
| socklen_t addrlen); | |||
| static int device=0; | |||
| static struct sockaddr_in source4 = {0}; | |||
| #ifdef CONFIG_IPV6 | |||
| static struct sockaddr_in6 source6 = {0}; | |||
| #endif | |||
| static struct sockaddr * source = 0; | |||
| static int sockaddr_size = 0; | |||
| static int is_bound [1024] = {0}; | |||
| #define next_func(x)\ | |||
| void set_next_##x(){\ | |||
| if (next_##x) return;\ | |||
| next_##x = dlsym(RTLD_NEXT, #x);\ | |||
| dlerror_handle();\ | |||
| return;\ | |||
| } | |||
| void dlerror_handle() | |||
| { | |||
| char *msg; | |||
| if ((msg = dlerror()) != NULL) { | |||
| fprintf(stderr, "socket: dlopen failed : %s\n", msg); | |||
| fflush(stderr); | |||
| exit(EXIT_FAILURE); | |||
| } | |||
| } | |||
| next_func(bind); | |||
| next_func(close); | |||
| next_func(setsockopt); | |||
| next_func(socket); | |||
| next_func(send); | |||
| next_func(sendto); | |||
| next_func(sendmsg); | |||
| next_func(connect); | |||
| void dobind(int sockfd) | |||
| { | |||
| if (source && sockfd < 1024 && !is_bound[sockfd]) { | |||
| set_next_bind(); | |||
| if (next_bind(sockfd, source, sockaddr_size)) { | |||
| perror("failed to bind to ip address"); | |||
| next_close(sockfd); | |||
| exit(EXIT_FAILURE); | |||
| } | |||
| is_bound[sockfd] = 1; | |||
| } | |||
| } | |||
| int connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen) | |||
| { | |||
| set_next_connect(); | |||
| dobind(sockfd); | |||
| return next_connect(sockfd, addr, addrlen); | |||
| } | |||
| ssize_t send(int sockfd, const void *buf, size_t len, int flags) | |||
| { | |||
| set_next_send(); | |||
| dobind(sockfd); | |||
| return next_send(sockfd, buf, len, flags); | |||
| } | |||
| ssize_t sendto(int sockfd, const void *buf, size_t len, int flags, | |||
| const struct sockaddr *dest_addr, socklen_t addrlen) | |||
| { | |||
| set_next_sendto(); | |||
| dobind(sockfd); | |||
| return next_sendto(sockfd, buf, len, flags, dest_addr, addrlen); | |||
| } | |||
| ssize_t sendmsg(int sockfd, const struct msghdr *msg, int flags) | |||
| { | |||
| set_next_sendmsg(); | |||
| dobind(sockfd); | |||
| return next_sendmsg(sockfd, msg, flags); | |||
| } | |||
| int bind (int sockfd, const struct sockaddr *addr, socklen_t addrlen) | |||
| { | |||
| set_next_bind(); | |||
| if (device && addr->sa_family == AF_PACKET) { | |||
| ((struct sockaddr_ll*)addr)->sll_ifindex=device; | |||
| } | |||
| else if (source && addr->sa_family == AF_INET) { | |||
| ((struct sockaddr_in*)addr)->sin_addr = source4.sin_addr; | |||
| } | |||
| #ifdef CONFIG_IPV6 | |||
| else if (source && addr->sa_family == AF_INET6) { | |||
| ((struct sockaddr_in6*)addr)->sin6_addr = source6.sin6_addr; | |||
| } | |||
| #endif | |||
| if (sockfd < 1024) | |||
| is_bound[sockfd] = 1; | |||
| return next_bind(sockfd, addr, addrlen); | |||
| } | |||
| int close (int sockfd) | |||
| { | |||
| set_next_close(); | |||
| if (sockfd < 1024) | |||
| is_bound[sockfd]=0; | |||
| return next_close(sockfd); | |||
| } | |||
| int setsockopt(int sockfd, int level, int optname, const void *optval, socklen_t optlen) | |||
| { | |||
| set_next_setsockopt(); | |||
| if (level == SOL_SOCKET && (optname == SO_MARK || optname == SO_BINDTODEVICE)) | |||
| return 0; | |||
| return next_setsockopt(sockfd, level, optname, optval, optlen); | |||
| } | |||
| int socket(int domain, int type, int protocol) | |||
| { | |||
| int handle; | |||
| const char *socket_str = getenv("DEVICE"); | |||
| const char *srcip_str = getenv("SRCIP"); | |||
| const char *fwmark_str = getenv("FWMARK"); | |||
| const char *family_str = getenv("FAMILY"); | |||
| const int iface_len = socket_str ? strnlen(socket_str, IFNAMSIZ) : 0; | |||
| int has_family = family_str && *family_str != 0; | |||
| int has_srcip = srcip_str && *srcip_str != 0; | |||
| const int fwmark = fwmark_str ? (int)strtol(fwmark_str, NULL, 0) : 0; | |||
| set_next_close(); | |||
| set_next_socket(); | |||
| set_next_send(); | |||
| set_next_setsockopt(); | |||
| set_next_sendmsg(); | |||
| set_next_sendto(); | |||
| set_next_connect(); | |||
| if(has_family) { | |||
| #ifdef CONFIG_IPV6 | |||
| if(domain == AF_INET && strncmp(family_str,"ipv6",4) == 0) | |||
| return -1; | |||
| #endif | |||
| if(domain == AF_INET6 && strncmp(family_str,"ipv4",4) == 0) | |||
| return -1; | |||
| } | |||
| if (domain != AF_INET | |||
| #ifdef CONFIG_IPV6 | |||
| && domain != AF_INET6 | |||
| #endif | |||
| ) { | |||
| return next_socket(domain, type, protocol); | |||
| } | |||
| if (iface_len > 0) { | |||
| if (iface_len == IFNAMSIZ) { | |||
| fprintf(stderr,"socket: Too long iface name\n"); | |||
| fflush(stderr); | |||
| exit(EXIT_FAILURE); | |||
| } | |||
| } | |||
| if (has_srcip) { | |||
| int s; | |||
| void * addr_buf; | |||
| if (domain == AF_INET) { | |||
| addr_buf = &source4.sin_addr; | |||
| sockaddr_size=sizeof source4; | |||
| memset(&source4, 0, sockaddr_size); | |||
| source4.sin_family = domain; | |||
| source = (struct sockaddr*)&source4; | |||
| } | |||
| #ifdef CONFIG_IPV6 | |||
| else { | |||
| addr_buf = &source6.sin6_addr; | |||
| sockaddr_size=sizeof source6; | |||
| memset(&source6, 0, sockaddr_size); | |||
| source6.sin6_family=domain; | |||
| source = (struct sockaddr*)&source6; | |||
| } | |||
| #endif | |||
| s = inet_pton(domain, srcip_str, addr_buf); | |||
| if (s == 0) { | |||
| fprintf(stderr, "socket: ip address invalid format for family %s\n", | |||
| domain == AF_INET ? "AF_INET" : domain == AF_INET6 ? | |||
| "AF_INET6" : "unknown"); | |||
| return -1; | |||
| } | |||
| if (s < 0) { | |||
| perror("inet_pton"); | |||
| exit(EXIT_FAILURE); | |||
| } | |||
| } | |||
| handle = next_socket(domain, type, protocol); | |||
| if (handle == -1 ) { | |||
| return handle; | |||
| } | |||
| if (iface_len > 0) { | |||
| device=if_nametoindex(socket_str); | |||
| if (next_setsockopt(handle, SOL_SOCKET, SO_BINDTODEVICE, | |||
| socket_str, iface_len + 1)) { | |||
| perror("socket: setting interface name failed with error"); | |||
| next_close(handle); | |||
| exit(EXIT_FAILURE); | |||
| } | |||
| } | |||
| if (fwmark > 0) { | |||
| if (next_setsockopt(handle, SOL_SOCKET, SO_MARK, | |||
| &fwmark, sizeof fwmark)) { | |||
| perror("failed setting mark for socket"); | |||
| next_close(handle); | |||
| exit(EXIT_FAILURE); | |||
| } | |||
| } | |||
| return handle; | |||
| } | |||