Source: https://git.alpinelinux.org/aports/tree/community/chromium/musl-sandbox.patch
musl uses different syscalls from glibc for some functions, so the sandbox has
to account for that
--
diff --git a/sandbox/linux/seccomp-bpf-helpers/syscall_parameters_restrictions.cc ./sandbox/linux/seccomp-bpf-helpers/syscall_parameters_restrictions.cc
index ff5a1c0..da56b9b 100644
--- a/sandbox/linux/seccomp-bpf-helpers/syscall_parameters_restrictions.cc
+++ ./sandbox/linux/seccomp-bpf-helpers/syscall_parameters_restrictions.cc
@@ -139,21 +139,11 @@ namespace sandbox {
 // present (as in newer versions of posix_spawn).
 ResultExpr RestrictCloneToThreadsAndEPERMFork() {
   const Arg<unsigned long> flags(0);
-
-  // TODO(mdempsky): Extend DSL to support (flags & ~mask1) == mask2.
-  const uint64_t kAndroidCloneMask = CLONE_VM | CLONE_FS | CLONE_FILES |
-                                     CLONE_SIGHAND | CLONE_THREAD |
-                                     CLONE_SYSVSEM;
-  const uint64_t kObsoleteAndroidCloneMask = kAndroidCloneMask | CLONE_DETACHED;
-
-  const uint64_t kGlibcPthreadFlags =
-      CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND | CLONE_THREAD |
-      CLONE_SYSVSEM | CLONE_SETTLS | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID;
-  const BoolExpr glibc_test = flags == kGlibcPthreadFlags;
-
-  const BoolExpr android_test =
-      AnyOf(flags == kAndroidCloneMask, flags == kObsoleteAndroidCloneMask,
-            flags == kGlibcPthreadFlags);
+  const int required = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND |
+                       CLONE_THREAD | CLONE_SYSVSEM;
+  const int safe = CLONE_SETTLS | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID |
+                   CLONE_DETACHED;
+  const BoolExpr thread_clone_ok = (flags&~safe)==required;
 
   // The following two flags are the two important flags in any vfork-emulating
   // clone call. EPERM any clone call that contains both of them.
@@ -163,7 +153,7 @@ ResultExpr RestrictCloneToThreadsAndEPERMFork() {
       AnyOf((flags & (CLONE_VM | CLONE_THREAD)) == 0,
             (flags & kImportantCloneVforkFlags) == kImportantCloneVforkFlags);
 
-  return If(IsAndroid() ? android_test : glibc_test, Allow())
+  return If(thread_clone_ok, Allow())
       .ElseIf(is_fork_or_clone_vfork, Error(EPERM))
       .Else(CrashSIGSYSClone());
 }
diff --git a/sandbox/linux/seccomp-bpf-helpers/syscall_sets.cc ./sandbox/linux/seccomp-bpf-helpers/syscall_sets.cc
index d9d1882..0567557 100644
--- a/sandbox/linux/seccomp-bpf-helpers/syscall_sets.cc
+++ ./sandbox/linux/seccomp-bpf-helpers/syscall_sets.cc
@@ -438,6 +438,7 @@
 #if defined(__i386__)
     case __NR_waitpid:
 #endif
+    case __NR_set_tid_address:
       return true;
     case __NR_clone:  // Should be parameter-restricted.
     case __NR_setns:  // Privileged.
@@ -450,7 +451,6 @@
 #if defined(__i386__) || defined(__x86_64__) || defined(__mips__)
     case __NR_set_thread_area:
 #endif
-    case __NR_set_tid_address:
     case __NR_unshare:
 #if !defined(__mips__) && !defined(__aarch64__)
     case __NR_vfork:
@@ -549,6 +549,8 @@
     case __NR_munlock:
     case __NR_munmap:
     case __NR_mseal:
+    case __NR_mremap:
+    case __NR_membarrier:
       return true;
     case __NR_madvise:
     case __NR_mincore:
@@ -566,7 +568,6 @@
     case __NR_modify_ldt:
 #endif
     case __NR_mprotect:
-    case __NR_mremap:
     case __NR_msync:
     case __NR_munlockall:
     case __NR_readahead:
diff --git a/sandbox/linux/system_headers/linux_syscalls.h ./sandbox/linux/system_headers/linux_syscalls.h
index 2b78a0c..b6fedb5 100644
--- a/sandbox/linux/system_headers/linux_syscalls.h
+++ b/sandbox/linux/system_headers/linux_syscalls.h
@@ -10,6 +10,7 @@
 #define SANDBOX_LINUX_SYSTEM_HEADERS_LINUX_SYSCALLS_H_
 
 #include "build/build_config.h"
+#include <sys/syscall.h>
 
 #if defined(__x86_64__)
 #include "sandbox/linux/system_headers/x86_64_linux_syscalls.h"
--- a/sandbox/policy/linux/bpf_renderer_policy_linux.cc
+++ b/sandbox/policy/linux/bpf_renderer_policy_linux.cc
@@ -106,8 +106,12 @@
 #endif
     case __NR_mremap:  // See crbug.com/149834.
     case __NR_pwrite64:
+    case __NR_pwritev2:
     case __NR_sched_get_priority_max:
     case __NR_sched_get_priority_min:
+    case __NR_sched_getparam:
+    case __NR_sched_getscheduler:
+    case __NR_sched_setscheduler:
     case __NR_sysinfo:
     case __NR_times:
     case __NR_uname:
--- a/sandbox/linux/seccomp-bpf-helpers/baseline_policy.cc
+++ b/sandbox/linux/seccomp-bpf-helpers/baseline_policy.cc
@@ -225,10 +225,15 @@
   if (sysno == __NR_getpriority || sysno ==__NR_setpriority)
     return RestrictGetSetpriority(current_pid);
 
+  // XXX: hacks for musl sandbox, calls needed?
+  if (sysno == __NR_sched_getparam || sysno == __NR_sched_getscheduler ||
+      sysno == __NR_sched_setscheduler) {
+    return Allow();
+  }
+
   // The scheduling syscalls are used in threading libraries and also heavily in
   // abseil. See for example https://crbug.com/1370394.
-  if (sysno == __NR_sched_getaffinity || sysno == __NR_sched_getparam ||
-      sysno == __NR_sched_getscheduler || sysno == __NR_sched_setscheduler) {
+  if (sysno == __NR_sched_getaffinity) {
     return RestrictSchedTarget(current_pid, sysno);
   }
 
