diff options
Diffstat (limited to 'src/shared/loopback-setup.c')
| -rw-r--r-- | src/shared/loopback-setup.c | 232 |
1 files changed, 232 insertions, 0 deletions
diff --git a/src/shared/loopback-setup.c b/src/shared/loopback-setup.c new file mode 100644 index 0000000..a02baf8 --- /dev/null +++ b/src/shared/loopback-setup.c @@ -0,0 +1,232 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <net/if.h> +#include <stdlib.h> + +#include "sd-netlink.h" + +#include "loopback-setup.h" +#include "missing_network.h" +#include "netlink-util.h" +#include "time-util.h" + +#define LOOPBACK_SETUP_TIMEOUT_USEC (5 * USEC_PER_SEC) + +struct state { + unsigned n_messages; + int rcode; + const char *error_message; + const char *success_message; + const char *eexist_message; +}; + +static int generic_handler(sd_netlink *rtnl, sd_netlink_message *m, void *userdata) { + struct state *s = ASSERT_PTR(userdata); + int r; + + assert(s->n_messages > 0); + s->n_messages--; + + errno = 0; + + r = sd_netlink_message_get_errno(m); + if (r == -EEXIST && s->eexist_message) + log_debug_errno(r, "%s", s->eexist_message); + else if (r < 0) + log_debug_errno(r, "%s: %m", s->error_message); + else + log_debug("%s", s->success_message); + + s->rcode = r; + return 0; +} + +static int start_loopback(sd_netlink *rtnl, struct state *s) { + _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *req = NULL; + int r; + + assert(rtnl); + assert(s); + + r = sd_rtnl_message_new_link(rtnl, &req, RTM_SETLINK, LOOPBACK_IFINDEX); + if (r < 0) + return r; + + r = sd_rtnl_message_link_set_flags(req, IFF_UP, IFF_UP); + if (r < 0) + return r; + + r = sd_netlink_call_async(rtnl, NULL, req, generic_handler, NULL, s, LOOPBACK_SETUP_TIMEOUT_USEC, "systemd-start-loopback"); + if (r < 0) + return r; + + s->n_messages ++; + return 0; +} + +static int add_ipv4_address(sd_netlink *rtnl, struct state *s) { + _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *req = NULL; + int r; + + assert(rtnl); + assert(s); + + r = sd_rtnl_message_new_addr(rtnl, &req, RTM_NEWADDR, LOOPBACK_IFINDEX, AF_INET); + if (r < 0) + return r; + + r = sd_rtnl_message_addr_set_prefixlen(req, 8); + if (r < 0) + return r; + + r = sd_rtnl_message_addr_set_flags(req, IFA_F_PERMANENT); + if (r < 0) + return r; + + r = sd_rtnl_message_addr_set_scope(req, RT_SCOPE_HOST); + if (r < 0) + return r; + + r = sd_netlink_message_append_in_addr(req, IFA_LOCAL, &(struct in_addr) { .s_addr = htobe32(INADDR_LOOPBACK) } ); + if (r < 0) + return r; + + r = sd_netlink_call_async(rtnl, NULL, req, generic_handler, NULL, s, USEC_INFINITY, "systemd-loopback-ipv4"); + if (r < 0) + return r; + + s->n_messages ++; + return 0; +} + +static int add_ipv6_address(sd_netlink *rtnl, struct state *s) { + _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *req = NULL; + int r; + + assert(rtnl); + assert(s); + + r = sd_rtnl_message_new_addr(rtnl, &req, RTM_NEWADDR, LOOPBACK_IFINDEX, AF_INET6); + if (r < 0) + return r; + + r = sd_rtnl_message_addr_set_prefixlen(req, 128); + if (r < 0) + return r; + + uint32_t flags = IFA_F_PERMANENT|IFA_F_NOPREFIXROUTE; + r = sd_rtnl_message_addr_set_flags(req, flags & 0xffu); /* rtnetlink wants low 8 bit of flags via regular flags field… */ + if (r < 0) + return r; + if ((flags & ~0xffu) != 0) { + r = sd_netlink_message_append_u32(req, IFA_FLAGS, flags); /* …and the rest of the flags via IFA_FLAGS */ + if (r < 0) + return r; + } + + r = sd_rtnl_message_addr_set_scope(req, RT_SCOPE_HOST); + if (r < 0) + return r; + + r = sd_netlink_message_append_in6_addr(req, IFA_LOCAL, &in6addr_loopback); + if (r < 0) + return r; + + r = sd_netlink_call_async(rtnl, NULL, req, generic_handler, NULL, s, USEC_INFINITY, "systemd-loopback-ipv6"); + if (r < 0) + return r; + + s->n_messages ++; + return 0; +} + +static int check_loopback(sd_netlink *rtnl) { + _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *req = NULL, *reply = NULL; + unsigned flags; + int r; + + r = sd_rtnl_message_new_link(rtnl, &req, RTM_GETLINK, LOOPBACK_IFINDEX); + if (r < 0) + return r; + + r = sd_netlink_call(rtnl, req, USEC_INFINITY, &reply); + if (r < 0) + return r; + + r = sd_rtnl_message_link_get_flags(reply, &flags); + if (r < 0) + return r; + + return flags & IFF_UP; +} + +int loopback_setup(void) { + _cleanup_(sd_netlink_unrefp) sd_netlink *rtnl = NULL; + struct state state_4 = { + .error_message = "Failed to add address 127.0.0.1 to loopback interface", + .success_message = "Successfully added address 127.0.0.1 to loopback interface", + .eexist_message = "127.0.0.1 has already been added to loopback interface", + }, state_6 = { + .error_message = "Failed to add address ::1 to loopback interface", + .success_message = "Successfully added address ::1 to loopback interface", + .eexist_message = "::1 has already been added to loopback interface", + }, state_up = { + .error_message = "Failed to bring loopback interface up", + .success_message = "Successfully brought loopback interface up", + }; + int r; + + /* Note, we, generally assume callers ignore the return code here (except test cases), hence only log add LOG_WARN level. */ + + r = sd_netlink_open(&rtnl); + if (r < 0) + return log_warning_errno(r, "Failed to open netlink, ignoring: %m"); + + /* Note that we add the IP addresses here explicitly even though the kernel does that too implicitly when + * setting up the loopback device. The reason we do this here a second time (and possibly race against the + * kernel) is that we want to synchronously wait until the IP addresses are set up correctly, see + * + * https://github.com/systemd/systemd/issues/5641 */ + + r = add_ipv4_address(rtnl, &state_4); + if (r < 0) + return log_warning_errno(r, "Failed to enqueue IPv4 loopback address add request, ignoring: %m"); + + r = add_ipv6_address(rtnl, &state_6); + if (r < 0) + return log_warning_errno(r, "Failed to enqueue IPv6 loopback address add request, ignoring: %m"); + + r = start_loopback(rtnl, &state_up); + if (r < 0) + return log_warning_errno(r, "Failed to enqueue loopback interface start request, ignoring: %m"); + + while (state_4.n_messages + state_6.n_messages + state_up.n_messages > 0) { + r = sd_netlink_wait(rtnl, LOOPBACK_SETUP_TIMEOUT_USEC); + if (r < 0) + return log_warning_errno(r, "Failed to wait for netlink event, ignoring: %m"); + + r = sd_netlink_process(rtnl, NULL); + if (r < 0) + return log_warning_errno(r, "Failed to process netlink event, ignoring: %m"); + } + + /* Note that we don't really care whether the addresses could be added or not */ + if (state_up.rcode != 0) { + + /* If we lack the permissions to configure the loopback device, but we find it to be already + * configured, let's exit cleanly, in order to supported unprivileged containers. */ + if (ERRNO_IS_PRIVILEGE(state_up.rcode)) { + r = check_loopback(rtnl); + if (r < 0) + log_debug_errno(r, "Failed to check if loopback device might already be up, ignoring: %m"); + else if (r > 0) { + log_debug("Configuring loopback failed, but device is already up, suppressing failure."); + return 0; + } + } + + return log_warning_errno(state_up.rcode, "Failed to configure loopback network device, ignoring: %m"); + } + + return 0; +} |