Add SetCapabilities for setting capabilities to an exact set.

sandbox/linux/services/syscall_wrappers.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SANDBOX_LINUX_SERVICES_SYSCALL_WRAPPERS_H_
 #define SANDBOX_LINUX_SERVICES_SYSCALL_WRAPPERS_H_
 
+#include <stdint.h>
 #include <sys/types.h>
 
 #include "sandbox/sandbox_export.h"
 
 struct sock_fprog;
 struct rlimit64;
+struct cap_hdr;
+struct cap_data;
 
 namespace sandbox {
 
 // Provide direct system call wrappers for a few common system calls.
 // These are guaranteed to perform a system call and do not rely on things such
 // as caching the current pid (c.f. getpid()) unless otherwise specified.
 
 SANDBOX_EXPORT pid_t sys_getpid(void);
 
 SANDBOX_EXPORT pid_t sys_gettid(void);
@@ skipping 16 matching lines @@
 SANDBOX_EXPORT int sys_seccomp(unsigned int operation,
                                unsigned int flags,
                                const struct sock_fprog* args);
 
 // Some libcs do not expose a prlimit64 wrapper.
 SANDBOX_EXPORT int sys_prlimit64(pid_t pid,
                                  int resource,
                                  const struct rlimit64* new_limit,
                                  struct rlimit64* old_limit);
 
+// Some libcs do not expose capget/capset wrappers. We want to use these
+// directly in order to avoid pulling in libcap2.
+SANDBOX_EXPORT int sys_capget(cap_hdr* hdrp, cap_data* datap);

[jln (very slow on Chromium), 2015/03/12 19:24:15]

How about putting C-style "struct cap_hdr" for these C-style APIs?

[rickyz (no longer on Chrome), 2015/03/12 23:36:01]

Done.

+SANDBOX_EXPORT int sys_capset(cap_hdr* hdrp, const cap_data* datap);
+
 }  // namespace sandbox
 
 #endif  // SANDBOX_LINUX_SERVICES_SYSCALL_WRAPPERS_H_