seccomp: add new seccomp_init_conservative() helper

This adds a new seccomp_init_conservative() helper call that is mostly just a
wrapper around seccomp_init(), but turns off NNP and adds in all secondary
archs, for best compatibility with everything else.

Pretty much all of our code used the very same constructs for these three
steps, hence unifying this in one small function makes things a lot shorter.

This also changes incorrect usage of the "scmp_filter_ctx" type at various
places. libseccomp defines it as typedef to "void*", i.e. it is a pointer type
(pretty poor choice already!) that casts implicitly to and from all other
pointer types (even poorer choice: you defined a confusing type now, and don't
even gain any bit of type safety through it...). A lot of the code assumed the
type would refer to a structure, and hence aded additional "*" here and there.
Remove that.

1 files changed, 19 insertions, 69 deletions

diff --git a/src/core/execute.c b/src/core/execute.c
index f435a079c7..668504c5cf 100644
--- a/src/core/execute.c
+++ b/src/core/execute.c
@@ -1197,7 +1197,7 @@ static bool skip_seccomp_unavailable(const Unit* u, const char* msg) {
 
 static int apply_seccomp(const Unit* u, const ExecContext *c) {
         uint32_t negative_action, action;
-        scmp_filter_ctx *seccomp;
+        scmp_filter_ctx seccomp;
         Iterator i;
         void *id;
         int r;
@@ -1248,7 +1248,7 @@ finish:
 }
 
 static int apply_address_families(const Unit* u, const ExecContext *c) {
-        scmp_filter_ctx *seccomp;
+        scmp_filter_ctx seccomp;
         Iterator i;
         int r;
 
@@ -1257,13 +1257,9 @@ static int apply_address_families(const Unit* u, const ExecContext *c) {
         if (skip_seccomp_unavailable(u, "RestrictAddressFamilies="))
                 return 0;
 
-        seccomp = seccomp_init(SCMP_ACT_ALLOW);
-        if (!seccomp)
-                return -ENOMEM;
-
-        r = seccomp_add_secondary_archs(seccomp);
+        r = seccomp_init_conservative(&seccomp, SCMP_ACT_ALLOW);
         if (r < 0)
-                goto finish;
+                return r;
 
         if (c->address_families_whitelist) {
                 int af, first = 0, last = 0;
@@ -1360,10 +1356,6 @@ static int apply_address_families(const Unit* u, const ExecContext *c) {
                 }
         }
 
-        r = seccomp_attr_set(seccomp, SCMP_FLTATR_CTL_NNP, 0);
-        if (r < 0)
-                goto finish;
-
         r = seccomp_load(seccomp);
 
 finish:
@@ -1372,7 +1364,7 @@ finish:
 }
 
 static int apply_memory_deny_write_execute(const Unit* u, const ExecContext *c) {
-        scmp_filter_ctx *seccomp;
+        scmp_filter_ctx seccomp;
         int r;
 
         assert(c);
@@ -1380,13 +1372,9 @@ static int apply_memory_deny_write_execute(const Unit* u, const ExecContext *c)
         if (skip_seccomp_unavailable(u, "MemoryDenyWriteExecute="))
                 return 0;
 
-        seccomp = seccomp_init(SCMP_ACT_ALLOW);
-        if (!seccomp)
-                return -ENOMEM;
-
-        r = seccomp_add_secondary_archs(seccomp);
+        r = seccomp_init_conservative(&seccomp, SCMP_ACT_ALLOW);
         if (r < 0)
-                goto finish;
+                return r;
 
         r = seccomp_rule_add(
                         seccomp,
@@ -1406,10 +1394,6 @@ static int apply_memory_deny_write_execute(const Unit* u, const ExecContext *c)
         if (r < 0)
                 goto finish;
 
-        r = seccomp_attr_set(seccomp, SCMP_FLTATR_CTL_NNP, 0);
-        if (r < 0)
-                goto finish;
-
         r = seccomp_load(seccomp);
 
 finish:
@@ -1424,7 +1408,7 @@ static int apply_restrict_realtime(const Unit* u, const ExecContext *c) {
                 SCHED_IDLE,
         };
 
-        scmp_filter_ctx *seccomp;
+        scmp_filter_ctx seccomp;
         unsigned i;
         int r, p, max_policy = 0;
 
@@ -1433,13 +1417,9 @@ static int apply_restrict_realtime(const Unit* u, const ExecContext *c) {
         if (skip_seccomp_unavailable(u, "RestrictRealtime="))
                 return 0;
 
-        seccomp = seccomp_init(SCMP_ACT_ALLOW);
-        if (!seccomp)
-                return -ENOMEM;
-
-        r = seccomp_add_secondary_archs(seccomp);
+        r = seccomp_init_conservative(&seccomp, SCMP_ACT_ALLOW);
         if (r < 0)
-                goto finish;
+                return r;
 
         /* Determine the highest policy constant we want to allow */
         for (i = 0; i < ELEMENTSOF(permitted_policies); i++)
@@ -1483,10 +1463,6 @@ static int apply_restrict_realtime(const Unit* u, const ExecContext *c) {
         if (r < 0)
                 goto finish;
 
-        r = seccomp_attr_set(seccomp, SCMP_FLTATR_CTL_NNP, 0);
-        if (r < 0)
-                goto finish;
-
         r = seccomp_load(seccomp);
 
 finish:
@@ -1495,7 +1471,7 @@ finish:
 }
 
 static int apply_protect_sysctl(Unit *u, const ExecContext *c) {
-        scmp_filter_ctx *seccomp;
+        scmp_filter_ctx seccomp;
         int r;
 
         assert(c);
@@ -1506,13 +1482,9 @@ static int apply_protect_sysctl(Unit *u, const ExecContext *c) {
         if (skip_seccomp_unavailable(u, "ProtectKernelTunables="))
                 return 0;
 
-        seccomp = seccomp_init(SCMP_ACT_ALLOW);
-        if (!seccomp)
-                return -ENOMEM;
-
-        r = seccomp_add_secondary_archs(seccomp);
+        r = seccomp_init_conservative(&seccomp, SCMP_ACT_ALLOW);
         if (r < 0)
-                goto finish;
+                return r;
 
         r = seccomp_rule_add(
                         seccomp,
@@ -1522,10 +1494,6 @@ static int apply_protect_sysctl(Unit *u, const ExecContext *c) {
         if (r < 0)
                 goto finish;
 
-        r = seccomp_attr_set(seccomp, SCMP_FLTATR_CTL_NNP, 0);
-        if (r < 0)
-                goto finish;
-
         r = seccomp_load(seccomp);
 
 finish:
@@ -1534,9 +1502,7 @@ finish:
 }
 
 static int apply_protect_kernel_modules(Unit *u, const ExecContext *c) {
-
-        scmp_filter_ctx *seccomp;
-        const char *sys;
+        scmp_filter_ctx seccomp;
         int r;
 
         assert(c);
@@ -1546,22 +1512,14 @@ static int apply_protect_kernel_modules(Unit *u, const ExecContext *c) {
         if (skip_seccomp_unavailable(u, "ProtectKernelModules="))
                 return 0;
 
-        seccomp = seccomp_init(SCMP_ACT_ALLOW);
-        if (!seccomp)
-                return -ENOMEM;
-
-        r = seccomp_add_secondary_archs(seccomp);
+        r = seccomp_init_conservative(&seccomp, SCMP_ACT_ALLOW);
         if (r < 0)
-                goto finish;
+                return r;
 
         r = seccomp_add_syscall_filter_set(seccomp, syscall_filter_sets + SYSCALL_FILTER_SET_MODULE, SCMP_ACT_ERRNO(EPERM));
         if (r < 0)
                 goto finish;
 
-        r = seccomp_attr_set(seccomp, SCMP_FLTATR_CTL_NNP, 0);
-        if (r < 0)
-                goto finish;
-
         r = seccomp_load(seccomp);
 
 finish:
@@ -1570,7 +1528,7 @@ finish:
 }
 
 static int apply_private_devices(Unit *u, const ExecContext *c) {
-        scmp_filter_ctx *seccomp;
+        scmp_filter_ctx seccomp;
         int r;
 
         assert(c);
@@ -1580,22 +1538,14 @@ static int apply_private_devices(Unit *u, const ExecContext *c) {
         if (skip_seccomp_unavailable(u, "PrivateDevices="))
                 return 0;
 
-        seccomp = seccomp_init(SCMP_ACT_ALLOW);
-        if (!seccomp)
-                return -ENOMEM;
-
-        r = seccomp_add_secondary_archs(seccomp);
+        r = seccomp_init_conservative(&seccomp, SCMP_ACT_ALLOW);
         if (r < 0)
-                goto finish;
+                return r;
 
         r = seccomp_add_syscall_filter_set(seccomp, syscall_filter_sets + SYSCALL_FILTER_SET_RAW_IO, SCMP_ACT_ERRNO(EPERM));
         if (r < 0)
                 goto finish;
 
-        r = seccomp_attr_set(seccomp, SCMP_FLTATR_CTL_NNP, 0);
-        if (r < 0)
-                goto finish;
-
         r = seccomp_load(seccomp);
 
 finish: