Based on 16115b0a7b7cdf08fb38084d857d572d8a9088dc Mon Sep 17 00:00:00 2001 From: Michal Sekletar Date: Thu, 24 Jul 2014 10:40:28 +0200 Subject: [PATCH] socket: introduce SELinuxContextFromNet option This makes possible to spawn service instances triggered by socket with MLS/MCS SELinux labels which are created based on information provided by connected peer. Implementation of label_get_child_mls_label derived from xinetd. Reviewed-by: Paul Moore --- man/systemd.socket.xml | 26 +++++++ src/core/execute.c | 30 +++++++-- src/core/execute.h | 1 src/core/load-fragment-gperf.gperf.m4 | 3 src/core/mount.c | 1 src/core/service.c | 4 - src/core/service.h | 3 src/core/socket.c | 16 +++- src/core/socket.h | 2 src/core/swap.c | 1 src/shared/label.c | 113 ++++++++++++++++++++++++++++++++++ src/shared/label.h | 2 12 files changed, 191 insertions(+), 11 deletions(-) --- man/systemd.socket.xml +++ man/systemd.socket.xml 2014-09-23 15:36:49.000000000 +0000 @@ -570,6 +570,32 @@ + SELinuxContextFromNet= + Takes a boolean + argument. When true systemd will attempt + to figure out the SELinux label used + for the instantiated service from the + information handed by the peer over the + network. Note that only the security + level is used from the information + provided by the peer. Other parts of + the resulting SELinux context originate + from either the target binary that is + effectively triggered by socket unit + are taken from the value of the + SELinuxContext= + option.This configuration option only + affects sockets with + Accept= mode set to + true. Also note that + this option is useful only when + MLS/MCS SELinux policy is + deployed. Defaults to + false. + + + + PipeSize= Takes an size in bytes. Controls the pipe buffer size --- src/core/execute.c +++ src/core/execute.c 2014-09-24 09:22:08.882735864 +0000 @@ -82,6 +82,7 @@ #include "selinux-util.h" #include "errno-list.h" #include "apparmor-util.h" +#include "label.h" #ifdef HAVE_SECCOMP #include "seccomp-util.h" @@ -1123,6 +1124,7 @@ int exec_spawn(ExecCommand *command, bool apply_chroot, bool apply_tty_stdin, bool confirm_spawn, + bool selinux_context_net, CGroupControllerMask cgroup_supported, const char *cgroup_path, const char *unit_id, @@ -1594,11 +1596,29 @@ int exec_spawn(ExecCommand *command, #endif #ifdef HAVE_SELINUX - if (context->selinux_context && use_selinux()) { - err = setexeccon(context->selinux_context); - if (err < 0 && !context->selinux_context_ignore) { - r = EXIT_SELINUX_CONTEXT; - goto fail_child; + if (use_selinux()) { + if (context->selinux_context) { + err = setexeccon(context->selinux_context); + if (err < 0 && !context->selinux_context_ignore) { + r = EXIT_SELINUX_CONTEXT; + goto fail_child; + } + } + + if (selinux_context_net && socket_fd >= 0) { + _cleanup_free_ char *label = NULL; + + err = label_get_child_mls_label(socket_fd, command->path, &label); + if (err < 0) { + r = EXIT_SELINUX_CONTEXT; + goto fail_child; + } + + err = setexeccon(label); + if (err < 0) { + r = EXIT_SELINUX_CONTEXT; + goto fail_child; + } } } #endif --- src/core/execute.h +++ src/core/execute.h 2014-09-23 15:46:26.000000000 +0000 @@ -195,6 +195,7 @@ int exec_spawn(ExecCommand *command, bool apply_chroot, bool apply_tty_stdin, bool confirm_spawn, + bool selinux_context_net, CGroupControllerMask cgroup_mask, const char *cgroup_path, const char *unit_id, --- src/core/load-fragment-gperf.gperf.m4 +++ src/core/load-fragment-gperf.gperf.m4 2014-09-23 00:00:00.000000000 +0000 @@ -242,6 +242,9 @@ Socket.SmackLabelIPOut, config_ `Socket.SmackLabel, config_parse_warn_compat, 0, 0 Socket.SmackLabelIPIn, config_parse_warn_compat, 0, 0 Socket.SmackLabelIPOut, config_parse_warn_compat, 0, 0') +m4_ifdef(`HAVE_SELINUX', +`Socket.SELinuxContextFromNet, config_parse_bool, 0, offsetof(Socket, selinux_context_from_net)', +`Socket.SELinuxContextFromNet, config_parse_warn_compat, 0, 0') EXEC_CONTEXT_CONFIG_ITEMS(Socket)m4_dnl CGROUP_CONTEXT_CONFIG_ITEMS(Socket)m4_dnl KILL_CONTEXT_CONFIG_ITEMS(Socket)m4_dnl --- src/core/mount.c +++ src/core/mount.c 2014-09-24 09:16:26.234235379 +0000 @@ -785,6 +785,7 @@ static int mount_spawn(Mount *m, ExecCom true, true, UNIT(m)->manager->confirm_spawn, + false, UNIT(m)->manager->cgroup_supported, UNIT(m)->cgroup_path, UNIT(m)->id, --- src/core/service.c +++ src/core/service.c 2014-09-23 15:49:24.000000000 +0000 @@ -1856,6 +1856,7 @@ static int service_spawn( apply_chroot, apply_tty_stdin, UNIT(s)->manager->confirm_spawn, + s->socket_fd_selinux_context_net, UNIT(s)->manager->cgroup_supported, path, UNIT(s)->id, @@ -3787,7 +3788,7 @@ static void service_bus_name_owner_chang } } -int service_set_socket_fd(Service *s, int fd, Socket *sock) { +int service_set_socket_fd(Service *s, int fd, Socket *sock, bool selinux_context_net) { _cleanup_free_ char *peer = NULL; int r; @@ -3825,6 +3826,7 @@ int service_set_socket_fd(Service *s, in } s->socket_fd = fd; + s->socket_fd_selinux_context_net = selinux_context_net; unit_ref_set(&s->accept_socket, UNIT(sock)); --- src/core/service.h +++ src/core/service.h 2014-09-23 15:51:13.000000000 +0000 @@ -159,6 +159,7 @@ struct Service { pid_t main_pid, control_pid; int socket_fd; + bool socket_fd_selinux_context_net; bool permissions_start_only; bool root_directory_start_only; bool remain_after_exit; @@ -204,7 +205,7 @@ extern const UnitVTable service_vtable; struct Socket; -int service_set_socket_fd(Service *s, int fd, struct Socket *socket); +int service_set_socket_fd(Service *s, int fd, struct Socket *socket, bool selinux_context_net); const char* service_state_to_string(ServiceState i) _const_; ServiceState service_state_from_string(const char *s) _pure_; --- src/core/socket.c +++ src/core/socket.c 2014-09-24 09:13:29.698735735 +0000 @@ -453,7 +453,8 @@ static void socket_dump(Unit *u, FILE *f "%sBroadcast: %s\n" "%sPassCredentials: %s\n" "%sPassSecurity: %s\n" - "%sTCPCongestion: %s\n", + "%sTCPCongestion: %s\n" + "%sSELinuxContextFromNet: %s\n", prefix, socket_state_to_string(s->state), prefix, socket_result_to_string(s->result), prefix, socket_address_bind_ipv6_only_to_string(s->bind_ipv6_only), @@ -466,7 +467,8 @@ static void socket_dump(Unit *u, FILE *f prefix, yes_no(s->broadcast), prefix, yes_no(s->pass_cred), prefix, yes_no(s->pass_sec), - prefix, strna(s->tcp_congestion)); + prefix, strna(s->tcp_congestion), + prefix, yes_no(s->selinux_context_from_net)); if (s->control_pid > 0) fprintf(f, @@ -1000,7 +1002,12 @@ static int socket_open_fds(Socket *s) { if (p->type == SOCKET_SOCKET) { - if (!know_label) { + if (!know_label && s->selinux_context_from_net) { + r = label_get_our_label(&label); + if (r < 0) + return r; + know_label = true; + } else if (!know_label) { if ((r = socket_instantiate_service(s)) < 0) return r; @@ -1247,6 +1254,7 @@ static int socket_spawn(Socket *s, ExecC true, true, UNIT(s)->manager->confirm_spawn, + s->selinux_context_from_net, UNIT(s)->manager->cgroup_supported, UNIT(s)->cgroup_path, UNIT(s)->id, @@ -1568,7 +1576,7 @@ static void socket_enter_running(Socket unit_choose_id(UNIT(service), name); - r = service_set_socket_fd(service, cfd, s); + r = service_set_socket_fd(service, cfd, s, s->selinux_context_from_net); if (r < 0) goto fail; --- src/core/socket.h +++ src/core/socket.h 2014-09-23 15:55:17.000000000 +0000 @@ -154,6 +154,8 @@ struct Socket { char *smack; char *smack_ip_in; char *smack_ip_out; + + bool selinux_context_from_net; }; /* Called from the service code when collecting fds */ --- src/core/swap.c +++ src/core/swap.c 2014-09-24 09:17:18.438735618 +0000 @@ -642,6 +642,7 @@ static int swap_spawn(Swap *s, ExecComma true, true, UNIT(s)->manager->confirm_spawn, + false, UNIT(s)->manager->cgroup_supported, UNIT(s)->cgroup_path, UNIT(s)->id, --- src/shared/label.c +++ src/shared/label.c 2014-09-23 00:00:00.000000000 +0000 @@ -31,6 +31,7 @@ #ifdef HAVE_SELINUX #include #include +#include #endif #include "label.h" @@ -41,6 +42,12 @@ #include "smack-util.h" #ifdef HAVE_SELINUX +DEFINE_TRIVIAL_CLEANUP_FUNC(security_context_t, freecon); +DEFINE_TRIVIAL_CLEANUP_FUNC(context_t, context_free); + +#define _cleanup_security_context_free_ _cleanup_(freeconp) +#define _cleanup_context_free_ _cleanup_(context_freep) + static struct selabel_handle *label_hnd = NULL; #endif @@ -243,6 +250,112 @@ fail: return r; } +int label_get_our_label(char **label) { + int r = -EOPNOTSUPP; + char *l = NULL; + +#ifdef HAVE_SELINUX + r = getcon(&l); + if (r < 0) + return r; + + *label = l; +#endif + + return r; +} + +int label_get_child_mls_label(int socket_fd, const char *exe, char **label) { + int r = -EOPNOTSUPP; + +#ifdef HAVE_SELINUX + + _cleanup_security_context_free_ security_context_t mycon = NULL, peercon = NULL, fcon = NULL, ret = NULL; + _cleanup_context_free_ context_t pcon = NULL, bcon = NULL; + security_class_t sclass; + + const char *range = NULL; + + assert(socket_fd >= 0); + assert(exe); + assert(label); + + r = getcon(&mycon); + if (r < 0) { + r = -EINVAL; + goto out; + } + + r = getpeercon(socket_fd, &peercon); + if (r < 0) { + r = -EINVAL; + goto out; + } + + r = getexeccon(&fcon); + if (r < 0) { + r = -EINVAL; + goto out; + } + + if (!fcon) { + /* If there is no context set for next exec let's use context + of target executable */ + r = getfilecon(exe, &fcon); + if (r < 0) { + r = -errno; + goto out; + } + } + + bcon = context_new(mycon); + if (!bcon) { + r = -ENOMEM; + goto out; + } + + pcon = context_new(peercon); + if (!pcon) { + r = -ENOMEM; + goto out; + } + + range = context_range_get(pcon); + if (!range) { + r = -errno; + goto out; + } + + r = context_range_set(bcon, range); + if (r) { + r = -errno; + goto out; + } + + freecon(mycon); + mycon = context_str(bcon); + if (!mycon) { + r = -errno; + goto out; + } + + sclass = string_to_security_class("process"); + r = security_compute_create(mycon, fcon, sclass, &ret); + if (r < 0) { + r = -EINVAL; + goto out; + } + + *label = ret; + r = 0; + +out: + if (r < 0 && security_getenforce() == 1) + return r; +#endif + return r; +} + int label_context_set(const char *path, mode_t mode) { int r = 0; --- src/shared/label.h +++ src/shared/label.h 2014-09-23 00:00:00.000000000 +0000 @@ -40,6 +40,8 @@ void label_context_clear(void); void label_free(const char *label); int label_get_create_label_from_exe(const char *exe, char **label); +int label_get_our_label(char **label); +int label_get_child_mls_label(int socket_fd, const char *exec, char **label); int label_mkdir(const char *path, mode_t mode);