On Mon, Sep 8, 2014 at 3:42 PM, Michal Sekletar <msekl...@redhat.com> wrote:
> 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 <pmo...@redhat.com>
> ---
>
> Changes in v5:
> * removed unneeded #include of libselinux headers from socket.c
> * fixed white-space issue in service_set_socket_fd
As all the comments from v4 has been fixed, please go ahead and commit this.
Cheers,
Tom
> 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 | 10 +--
> 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, 190 insertions(+), 15 deletions(-)
>
> diff --git a/man/systemd.socket.xml b/man/systemd.socket.xml
> index 7a63348..dad0267 100644
> --- a/man/systemd.socket.xml
> +++ b/man/systemd.socket.xml
> @@ -676,6 +676,32 @@
> </varlistentry>
>
> <varlistentry>
> +
> <term><varname>SELinuxContextFromNet=</varname></term>
> + <listitem><para>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
> + <varname>SELinuxContext=</varname>
> + option.This configuration option only
> + affects sockets with
> + <varname>Accept=</varname> mode set to
> + <literal>true</literal>. Also note that
> + this option is useful only when
> + MLS/MCS SELinux policy is
> + deployed. Defaults to
> + <literal>false</literal>.
> + </para></listitem>
> + </varlistentry>
> +
> + <varlistentry>
> <term><varname>PipeSize=</varname></term>
> <listitem><para>Takes a size in
> bytes. Controls the pipe buffer size
> diff --git a/src/core/execute.c b/src/core/execute.c
> index 0a59147..37b9ed4 100644
> --- a/src/core/execute.c
> +++ b/src/core/execute.c
> @@ -83,6 +83,7 @@
> #include "af-list.h"
> #include "mkdir.h"
> #include "apparmor-util.h"
> +#include "label.h"
>
> #ifdef HAVE_SECCOMP
> #include "seccomp-util.h"
> @@ -1646,11 +1647,29 @@ 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 f31f0c9..274fc2f 100644
> --- a/src/core/execute.h
> +++ b/src/core/execute.h
> @@ -200,6 +200,7 @@ 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 24aa80d..8bbf27c 100644
> --- a/src/core/load-fragment-gperf.gperf.m4
> +++ b/src/core/load-fragment-gperf.gperf.m4
> @@ -262,6 +262,9 @@ 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 f3775f2..255621e 100644
> --- a/src/core/service.c
> +++ b/src/core/service.c
> @@ -893,9 +893,10 @@ static int service_spawn(
> **argv = NULL, **final_env = NULL, **our_env = NULL;
> const char *path;
> ExecParameters exec_params = {
> - .apply_permissions = apply_permissions,
> - .apply_chroot = apply_chroot,
> - .apply_tty_stdin = apply_tty_stdin,
> + .apply_permissions = apply_permissions,
> + .apply_chroot = apply_chroot,
> + .apply_tty_stdin = apply_tty_stdin,
> + .selinux_context_net = s->socket_fd_selinux_context_net
> };
>
> assert(s);
> @@ -2711,7 +2712,7 @@ 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;
>
> @@ -2749,6 +2750,7 @@ 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 5bcfd14..f9ec6dc 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;
>
> bool permissions_start_only;
> bool root_directory_start_only;
> @@ -203,7 +204,7 @@ 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 68e21e6..00d5fd1 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 eede705..a2e0899 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 25a8b36..02b41f0 100644
> --- a/src/shared/label.c
> +++ b/src/shared/label.c
> @@ -31,6 +31,7 @@
> #ifdef HAVE_SELINUX
> #include <selinux/selinux.h>
> #include <selinux/label.h>
> +#include <selinux/context.h>
> #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 7294820..068a7ac 100644
> --- a/src/shared/label.h
> +++ b/src/shared/label.h
> @@ -39,6 +39,8 @@ 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);
>
> --
> 2.0.1
>
> _______________________________________________
> systemd-devel mailing list
> systemd-devel@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/systemd-devel
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