commit 7461cd30676da62324271ddd7b7d347eeff40266 Author: Nick Mathewson nickm@torproject.org Date: Thu Nov 16 12:44:47 2017 -0500

Permit kill(pid, 0) in the seccomp2 sandbox.

We don't want to allow general signals to be sent, but there's no problem sending a kill(0) to probe whether a process is there.

Fixes bug 24198; bugfix on 0.2.5.1-alpha when the seccomp2 sandbox was introduced. --- changes/bug24198 | 4 ++++ src/common/sandbox.c | 16 +++++++++++++++- 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/changes/bug24198 b/changes/bug24198 new file mode 100644 index 000000000..679070687 --- /dev/null +++ b/changes/bug24198 @@ -0,0 +1,4 @@ + o Minor bugfixes (controller, linux seccomp2 sandbox): + - Avoid a crash when attempting to use the seccomp2 sandbox + together with the OwningControllerProcess feature. + Fixes bug 24198; bugfix on 0.2.5.1-alpha. diff --git a/src/common/sandbox.c b/src/common/sandbox.c index 7f4511db2..0b862a549 100644 --- a/src/common/sandbox.c +++ b/src/common/sandbox.c @@ -1050,6 +1050,19 @@ sb_stat64(scmp_filter_ctx ctx, sandbox_cfg_t *filter) } #endif

+static int +sb_kill(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + (void) filter; +#ifdef __NR_kill + /* Allow killing anything with signal 0 -- it isn't really a kill. */ + return seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(kill), + SCMP_CMP(1, SCMP_CMP_EQ, 0)); +#else + return 0; +#endif +} + /** * Array of function pointers responsible for filtering different syscalls at * a parameter level. @@ -1088,7 +1101,8 @@ static sandbox_filter_func_t filter_func[] = { sb_socket, sb_setsockopt, sb_getsockopt, - sb_socketpair + sb_socketpair, + sb_kill };

const char *