Manpages - seccomp_syscall_resolve_name.3

seccomp_syscall_resolve_name - Resolve a syscall name

  #include <seccomp.h>

  int seccomp_syscall_resolve_name(const char *name);
  int seccomp_syscall_resolve_name_arch(uint32_t arch_token,
   const char *name);
  int seccomp_syscall_resolve_name_rewrite(uint32_t arch_token,
   const char *name);
  char *seccomp_syscall_resolve_num_arch(uint32_t arch_token, int num);

  Link with -lseccomp.

The seccomp_syscall_resolve_name(), seccomp_syscall_resolve_name_arch(), and seccomp_syscall_resolve_name_rewrite() functions resolve the commonly used syscall name to the syscall number used by the kernel and the rest of the libseccomp API, with seccomp_syscall_resolve_name_rewrite() rewriting the syscall number for architectures that modify the syscall. Syscall rewriting typically happens in case of a multiplexed syscall, like socketcall*(2) or *ipc*(2) on x86. *seccomp_syscall_resolve_num_arch() function resolves the syscall number used by the kernel to the commonly used syscall name.

The caller is responsible for freeing the returned string from seccomp_syscall_resolve_num_arch().

In the case of seccomp_syscall_resolve_name(), seccomp_syscall_resolve_name_arch(), and seccomp_syscall_resolve_name_rewrite() the associated syscall number is returned, with the negative pseudo syscall number being returned in cases where the given syscall does not exist for the architecture. The value __NR_SCMP_ERROR is returned in case of error. In all cases, the return value is suitable for use in any libseccomp API function which requires the syscall number, examples include *seccomp_rule_add*() and *seccomp_rule_add_exact*().

In the case of seccomp_syscall_resolve_num_arch() the associated syscall name is returned and it remains the callers responsibility to free the returned string via *free*(3).

  #include <seccomp.h>

  int main(int argc, char *argv[])
  {
  	int rc = -1;
  	scmp_filter_ctx ctx;

  	ctx = seccomp_init(SCMP_ACT_KILL);
  	if (ctx == NULL)
  		goto out;

  	/* ... */

  	rc = seccomp_rule_add(ctx, SCMP_ACT_ALLOW,
  	                      seccomp_syscall_resolve_name("open"), 0);
  	if (rc < 0)
  		goto out;

  	/* ... */

  	rc = seccomp_load(ctx);
  	if (rc < 0)
  		goto out;

  	/* ... */

  out:
  	seccomp_release(ctx);
  	return -rc;
  }

In case of bare syscalls implemented on top of a multiplexed syscall, seccomp_syscall_resolve_name() and seccomp_syscall_resolve_name_arch() can be used to verify if a bare syscall is implemented for a specific architecture, while seccomp_syscall_resolve_name_rewrite() can be used to determine the underlying multiplexed syscall.

While the seccomp filter can be generated independent of the kernel, kernel support is required to load and enforce the seccomp filter generated by libseccomp.

The libseccomp project site, with more information and the source code repository, can be found at https://github.com/seccomp/libseccomp. This tool, as well as the libseccomp library, is currently under development, please report any bugs at the project site or directly to the author.

Paul Moore <paul@paul-moore.com>

*seccomp_rule_add*(3), *seccomp_rule_add_exact*(3)