nspawn: --private-network should imply CAP_NET_ADMIN

diff --git a/man/systemd-nspawn.xml b/man/systemd-nspawn.xml
index 7a88436bcfd17ae61b5f619994e785b72b702884..ffd707092c013d87553066f9ac46ff26a4cd2275 100644 (file)
--- a/man/systemd-nspawn.xml
+++ b/man/systemd-nspawn.xml
@@ -277,7 +277,15 @@
                                 the container. This makes all network
                                 interfaces unavailable in the
                                 container, with the exception of the
-                                loopback device.</para></listitem>
+                                loopback device and those specified
+                                with
+                                <option>--network-interface=</option>. If
+                                this option is specified the
+                                CAP_NET_ADMIN capability will be added
+                                to the set of capabilities the
+                                container retains. The latter may be
+                                disabled by using
+                                <option>--drop-capability=</option>.</para></listitem>
                         </varlistentry>
 
                         <varlistentry>
@@ -290,7 +298,13 @@
                                 namespace and place it in the
                                 container. When the container
                                 terminates it is moved back to the
-                                host namespace.</para></listitem>
+                                host namespace. Note that
+                                <option>--network-interface=</option>
+                                implies
+                                <option>--private-network</option>. This
+                                option may be used more than once to
+                                add multiple network interfaces to the
+                                container.</para></listitem>
                         </varlistentry>
 
                         <varlistentry>
@@ -323,8 +337,11 @@
                                 CAP_SYS_CHROOT, CAP_SYS_NICE,
                                 CAP_SYS_PTRACE, CAP_SYS_TTY_CONFIG,
                                 CAP_SYS_RESOURCE, CAP_SYS_BOOT,
-                                CAP_AUDIT_WRITE, CAP_AUDIT_CONTROL. If
-                                the special value
+                                CAP_AUDIT_WRITE,
+                                CAP_AUDIT_CONTROL. Also CAP_NET_ADMIN
+                                is retained if
+                                <option>--private-network</option> is
+                                specified. If the special value
                                 <literal>all</literal> is passed all
                                 capabilities are
                                 retained.</para></listitem>

diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index 679c005071dc2558ec11f6a85a98823bf109c9cd..9ce1fa9b49cd72fdcf4b683ba231ccd5fd862488 100644 (file)
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -216,6 +216,7 @@ static int parse_argv(int argc, char *argv[]) {
         };
 
         int c, r;
+        uint64_t plus = 0, minus = 0;
 
         assert(argc >= 0);
         assert(argv);
@@ -325,9 +326,9 @@ static int parse_argv(int argc, char *argv[]) {
 
                                 if (streq(t, "all")) {
                                         if (c == ARG_CAPABILITY)
-                                                arg_retain = (uint64_t) -1;
+                                                plus = (uint64_t) -1;
                                         else
-                                                arg_retain = 0;
+                                                minus = (uint64_t) -1;
                                 } else {
                                         if (cap_from_name(t, &cap) < 0) {
                                                 log_error("Failed to parse capability %s.", t);
@@ -335,9 +336,9 @@ static int parse_argv(int argc, char *argv[]) {
                                         }
 
                                         if (c == ARG_CAPABILITY)
-                                                arg_retain |= 1ULL << (uint64_t) cap;
+                                                plus |= 1ULL << (uint64_t) cap;
                                         else
-                                                arg_retain &= ~(1ULL << (uint64_t) cap);
+                                                minus |= 1ULL << (uint64_t) cap;
                                 }
                         }
 
@@ -460,6 +461,8 @@ static int parse_argv(int argc, char *argv[]) {
                 return -EINVAL;
         }
 
+        arg_retain = (arg_retain | plus | (arg_private_network ? 1ULL << CAP_NET_ADMIN : 0)) & ~minus;
+
         return 1;
 }