From 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 | 29 +++++-- src/core/execute.h | 1 + src/core/load-fragment-gperf.gperf.m4 | 3 + src/core/service.c | 4 +- src/core/service.h | 3 +- src/core/socket.c | 16 ++-- src/core/socket.h | 2 + src/shared/label.c | 113 ++++++++++++++++++++++++++ src/shared/label.h | 2 + 10 files changed, 187 insertions(+), 12 deletions(-) diff --git a/man/systemd.socket.xml b/man/systemd.socket.xml index 7a63348ca..dad026746 100644 --- a/man/systemd.socket.xml +++ b/man/systemd.socket.xml @@ -675,6 +675,32 @@ for details. + + 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 a size in diff --git a/src/core/execute.c b/src/core/execute.c index db755777c..8c9dfde00 100644 --- a/src/core/execute.c +++ b/src/core/execute.c @@ -84,6 +84,7 @@ #include "mkdir.h" #include "apparmor-util.h" #include "bus-kernel.h" +#include "label.h" #ifdef HAVE_SECCOMP #include "seccomp-util.h" @@ -1665,11 +1666,29 @@ static int exec_child(ExecCommand *command, #endif #ifdef HAVE_SELINUX - if (context->selinux_context && use_selinux()) { - err = setexeccon(context->selinux_context); - if (err < 0 && !context->selinux_context_ignore) { - *error = EXIT_SELINUX_CONTEXT; - return err; + if (use_selinux()) { + if (context->selinux_context) { + err = setexeccon(context->selinux_context); + if (err < 0 && !context->selinux_context_ignore) { + *error = EXIT_SELINUX_CONTEXT; + return err; + } + } + + if (params->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) { + *error = EXIT_SELINUX_CONTEXT; + return err; + } + + err = setexeccon(label); + if (err < 0) { + *error = EXIT_SELINUX_CONTEXT; + return err; + } } } #endif diff --git a/src/core/execute.h b/src/core/execute.h index 9c1f249cd..6f35736ed 100644 --- a/src/core/execute.h +++ b/src/core/execute.h @@ -204,6 +204,7 @@ struct ExecParameters { bool apply_chroot; bool apply_tty_stdin; bool confirm_spawn; + bool selinux_context_net; CGroupControllerMask cgroup_supported; const char *cgroup_path; const char *runtime_prefix; diff --git a/src/core/load-fragment-gperf.gperf.m4 b/src/core/load-fragment-gperf.gperf.m4 index e764d68ce..050c5d819 100644 --- a/src/core/load-fragment-gperf.gperf.m4 +++ b/src/core/load-fragment-gperf.gperf.m4 @@ -265,6 +265,9 @@ Socket.SmackLabelIPOut, config_parse_string, 0, `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 diff --git a/src/core/service.c b/src/core/service.c index 3f6595c5c..395e0ca8c 100644 --- a/src/core/service.c +++ b/src/core/service.c @@ -901,6 +901,7 @@ static int service_spawn( .apply_chroot = apply_chroot, .apply_tty_stdin = apply_tty_stdin, .bus_endpoint_fd = -1, + .selinux_context_net = s->socket_fd_selinux_context_net }; assert(s); @@ -2748,7 +2749,7 @@ static void service_bus_name_owner_change( } } -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; @@ -2786,6 +2787,7 @@ int service_set_socket_fd(Service *s, int fd, Socket *sock) { } s->socket_fd = fd; + s->socket_fd_selinux_context_net = selinux_context_net; unit_ref_set(&s->accept_socket, UNIT(sock)); diff --git a/src/core/service.h b/src/core/service.h index ad0b3b381..0db0c4d64 100644 --- a/src/core/service.h +++ b/src/core/service.h @@ -161,6 +161,7 @@ struct Service { pid_t main_pid, control_pid; int socket_fd; + bool socket_fd_selinux_context_net; int bus_endpoint_fd; @@ -205,7 +206,7 @@ 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_; diff --git a/src/core/socket.c b/src/core/socket.c index 68e21e60a..00d5fd119 100644 --- a/src/core/socket.c +++ b/src/core/socket.c @@ -489,7 +489,8 @@ static void socket_dump(Unit *u, FILE *f, const char *prefix) { "%sPassCredentials: %s\n" "%sPassSecurity: %s\n" "%sTCPCongestion: %s\n" - "%sRemoveOnStop: %s\n", + "%sRemoveOnStop: %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), @@ -504,7 +505,8 @@ static void socket_dump(Unit *u, FILE *f, const char *prefix) { prefix, yes_no(s->pass_cred), prefix, yes_no(s->pass_sec), prefix, strna(s->tcp_congestion), - prefix, yes_no(s->remove_on_stop)); + prefix, yes_no(s->remove_on_stop), + prefix, yes_no(s->selinux_context_from_net)); if (s->control_pid > 0) fprintf(f, @@ -1128,8 +1130,12 @@ static int socket_open_fds(Socket *s) { continue; 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) { r = socket_instantiate_service(s); if (r < 0) @@ -1821,7 +1827,7 @@ static void socket_enter_running(Socket *s, int cfd) { 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; diff --git a/src/core/socket.h b/src/core/socket.h index eede70564..a2e08998c 100644 --- a/src/core/socket.h +++ b/src/core/socket.h @@ -165,6 +165,8 @@ struct Socket { char *smack_ip_in; char *smack_ip_out; + bool selinux_context_from_net; + char *user, *group; }; diff --git a/src/shared/label.c b/src/shared/label.c index 25a8b361b..02b41f02d 100644 --- a/src/shared/label.c +++ b/src/shared/label.c @@ -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; diff --git a/src/shared/label.h b/src/shared/label.h index cb2ec79ee..ce1e5c3f5 100644 --- a/src/shared/label.h +++ b/src/shared/label.h @@ -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); -- 2.30.2