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exec: imply NoNewPriviliges= only when seccomp filters are used in user mode

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This commit is contained in:
Lennart Poettering 2014-02-26 02:28:52 +01:00
parent 9c423fbf2a
commit f513e420c8
3 changed files with 46 additions and 28 deletions
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59
man/systemd.exec.xml
View File

@ -1010,8 +1010,8 @@
<varlistentry>
<term><varname>SystemCallFilter=</varname></term>
<listitem><para>Takes a space-separated
list of system call
<listitem><para>Takes a
space-separated list of system call
names. If this setting is used, all
system calls executed by the unit
processes except for the listed ones
@ -1023,12 +1023,13 @@
the effect is inverted: only the
listed system calls will result in
immediate process termination
(blacklisting). If this option is used,
(blacklisting). If running in user
mode and this option is used,
<varname>NoNewPrivileges=yes</varname>
is implied. This feature makes use of
the Secure Computing Mode 2 interfaces
of the kernel ('seccomp filtering')
and is useful for enforcing a minimal
is implied. This feature makes use of the
Secure Computing Mode 2 interfaces of
the kernel ('seccomp filtering') and
is useful for enforcing a minimal
sandboxing environment. Note that the
<function>execve</function>,
<function>rt_sigreturn</function>,
@ -1096,28 +1097,31 @@
<constant>x86</constant>,
<constant>x86-64</constant>,
<constant>x32</constant>,
<constant>arm</constant> as well as the
special identifier
<constant>native</constant>. Only system
calls of the specified architectures
will be permitted to processes of this
unit. This is an effective way to
disable compatibility with non-native
architectures for processes, for
example to prohibit execution of
32-bit x86 binaries on 64-bit x86-64
systems. The special
<constant>arm</constant> as well as
the special identifier
<constant>native</constant>. Only
system calls of the specified
architectures will be permitted to
processes of this unit. This is an
effective way to disable compatibility
with non-native architectures for
processes, for example to prohibit
execution of 32-bit x86 binaries on
64-bit x86-64 systems. The special
<constant>native</constant> identifier
implicitly maps to the native
architecture of the system (or more
strictly: to the architecture the
system manager is compiled for). Note
that setting this option to a
non-empty list implies that
<constant>native</constant> is included
too. By default, this option is set to
the empty list, i.e. no architecture
system call filtering is
system manager is compiled for). If
running in user mode and this option
is used,
<varname>NoNewPrivileges=yes</varname>
is implied. Note that setting this
option to a non-empty list implies
that <constant>native</constant> is
included too. By default, this option
is set to the empty list, i.e. no
architecture system call filtering is
applied.</para></listitem>
</varlistentry>
@ -1149,7 +1153,10 @@
sockets only) are unaffected. Note
that this option has no effect on
32bit x86 and is ignored (but works
correctly on x86-64). By default no
correctly on x86-64). If running in user
mode and this option is used,
<varname>NoNewPrivileges=yes</varname>
is implied. By default no
restriction applies, all address
families are accessible to
processes. If assigned the empty

7
src/core/execute.c
View File

@ -1706,7 +1706,8 @@ int exec_spawn(ExecCommand *command,
}
#ifdef HAVE_SECCOMP
if (context->address_families) {
if (context->address_families_whitelist ||
!set_isempty(context->address_families)) {
err = apply_address_families(context);
if (err < 0) {
r = EXIT_ADDRESS_FAMILIES;
@ -1714,7 +1715,9 @@ int exec_spawn(ExecCommand *command,
}
}
if (context->syscall_filter || context->syscall_archs) {
if (context->syscall_whitelist ||
!set_isempty(context->syscall_filter) ||
!set_isempty(context->syscall_archs)) {
err = apply_seccomp(context);
if (err < 0) {
r = EXIT_SECCOMP;

8
src/core/unit.c
View File

@ -2817,6 +2817,14 @@ int unit_exec_context_patch_defaults(Unit *u, ExecContext *c) {
return r;
}
if (u->manager->running_as == SYSTEMD_USER &&
(c->syscall_whitelist ||
!set_isempty(c->syscall_filter) ||
!set_isempty(c->syscall_archs) ||
c->address_families_whitelist ||
!set_isempty(c->address_families)))
c->no_new_privileges = true;
return 0;
}