diff --git a/configure b/configure index f7c2d7a7..5ef5cd4c 100755 --- a/configure +++ b/configure @@ -336,6 +336,20 @@ EOF rm -f $TMPDIR/strtest.c $TMPDIR/strtest } +check_cap() +{ + if ${PKG_CONFIG} libcap --exists + then + echo "HAVE_CAP:=y" >>$CONFIG + echo "yes" + + echo 'CFLAGS += -DHAVE_LIBCAP' `${PKG_CONFIG} libcap --cflags` >>$CONFIG + echo 'LDLIBS +=' `${PKG_CONFIG} libcap --libs` >> $CONFIG + else + echo "no" + fi +} + quiet_config() { cat <> $CONFIG echo "%.o: %.c" >> $CONFIG echo ' $(QUIET_CC)$(CC) $(CFLAGS) $(EXTRA_CFLAGS) -c -o $@ $<' >> $CONFIG diff --git a/include/utils.h b/include/utils.h index 0394268e..e7bffe8a 100644 --- a/include/utils.h +++ b/include/utils.h @@ -299,4 +299,6 @@ size_t strlcpy(char *dst, const char *src, size_t size); size_t strlcat(char *dst, const char *src, size_t size); #endif +void drop_cap(void); + #endif /* __UTILS_H__ */ diff --git a/ip/ip.c b/ip/ip.c index e0cd96cb..e716fed8 100644 --- a/ip/ip.c +++ b/ip/ip.c @@ -174,6 +174,18 @@ int main(int argc, char **argv) char *batch_file = NULL; int color = 0; + /* to run vrf exec without root, capabilities might be set, drop them + * if not needed as the first thing. + * execv will drop them for the child command. + * vrf exec requires: + * - cap_dac_override to create the cgroup subdir in /sys + * - cap_sys_admin to load the BPF program + * - cap_net_admin to set the socket into the cgroup + */ + if (argc < 3 || strcmp(argv[1], "vrf") != 0 || + strcmp(argv[2], "exec") != 0) + drop_cap(); + basename = strrchr(argv[0], '/'); if (basename == NULL) basename = argv[0]; diff --git a/ip/ipvrf.c b/ip/ipvrf.c index f9277e1e..8a6b7f97 100644 --- a/ip/ipvrf.c +++ b/ip/ipvrf.c @@ -436,6 +436,8 @@ out2: out: free(mnt); + drop_cap(); + return rc; } diff --git a/lib/utils.c b/lib/utils.c index 4fe4ac1e..dadefb55 100644 --- a/lib/utils.c +++ b/lib/utils.c @@ -30,6 +30,9 @@ #include #include #include +#ifdef HAVE_LIBCAP +#include +#endif #include "rt_names.h" #include "utils.h" @@ -1495,3 +1498,22 @@ size_t strlcat(char *dst, const char *src, size_t size) return dlen + strlcpy(dst + dlen, src, size - dlen); } #endif + +void drop_cap(void) +{ +#ifdef HAVE_LIBCAP + /* don't harmstring root/sudo */ + if (getuid() != 0 && geteuid() != 0) { + cap_t capabilities; + + capabilities = cap_get_proc(); + if (!capabilities) + exit(EXIT_FAILURE); + if (cap_clear(capabilities) != 0) + exit(EXIT_FAILURE); + if (cap_set_proc(capabilities) != 0) + exit(EXIT_FAILURE); + cap_free(capabilities); + } +#endif +} diff --git a/man/man8/ip-vrf.8 b/man/man8/ip-vrf.8 index 18789339..1a42cebe 100644 --- a/man/man8/ip-vrf.8 +++ b/man/man8/ip-vrf.8 @@ -63,6 +63,14 @@ a VRF other than the default VRF (main table). A command can be run against the default VRF by passing the "default" as the VRF name. This is useful if the current shell is associated with another VRF (e.g, Management VRF). +This command requires the system to be booted with cgroup v2 (e.g. with systemd, +add systemd.unified_cgroup_hierarchy=1 to the kernel command line). + +This command also requires to be ran as root or with the CAP_SYS_ADMIN, +CAP_NET_ADMIN and CAP_DAC_OVERRIDE capabilities. If built with libcap and if +capabilities are added to the ip binary program via setcap, the program will +drop them as the first thing when invoked, unless the command is vrf exec. + .TP .B ip vrf identify [PID] - Report VRF association for process .sp