diff --git a/doc/manual/command-ref/conf-file.xml b/doc/manual/command-ref/conf-file.xml index 616983bc7..cde32b35f 100644 --- a/doc/manual/command-ref/conf-file.xml +++ b/doc/manual/command-ref/conf-file.xml @@ -643,6 +643,23 @@ password my-password + allow-new-privileges + + (Linux-specific.) By default, builders on Linux + cannot acquire new privileges by calling setuid/setgid programs or + programs that have file capabilities. For example, programs such + as sudo or ping will + fail. (Note that in sandbox builds, no such programs are available + unless you bind-mount them into the sandbox via the + option.) You can allow the + use of such programs by enabling this option. This is impure and + usually undesirable, but may be useful in certain scenarios + (e.g. to spin up containers or set up userspace network interfaces + in tests). + + + + diff --git a/src/libstore/build.cc b/src/libstore/build.cc index f40a8c549..355fb3b7d 100644 --- a/src/libstore/build.cc +++ b/src/libstore/build.cc @@ -2340,6 +2340,9 @@ void setupSeccomp() seccomp_rule_add(ctx, SCMP_ACT_ERRNO(ENOTSUP), SCMP_SYS(fsetxattr), 0) != 0) throw SysError("unable to add seccomp rule"); + if (seccomp_attr_set(ctx, SCMP_FLTATR_CTL_NNP, settings.allowNewPrivileges ? 0 : 1) != 0) + throw SysError("unable to set 'no new privileges' seccomp attribute"); + if (seccomp_load(ctx) != 0) throw SysError("unable to load seccomp BPF program"); #endif diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh index af37ec61d..c8d67b071 100644 --- a/src/libstore/globals.hh +++ b/src/libstore/globals.hh @@ -321,6 +321,12 @@ public: Setting userAgentSuffix{this, "", "user-agent-suffix", "String appended to the user agent in HTTP requests."}; + +#if __linux__ + Setting allowNewPrivileges{this, false, "allow-new-privileges", + "Whether builders can acquire new privileges by calling programs with " + "setuid/setgid bits or with file capabilities."}; +#endif };