From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= Date: Wed, 22 Aug 2018 19:02:48 +0200 Subject: [PATCH] seccomp: prefer SCMP_ACT_KILL_PROCESS if available MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The upcoming libseccomp release should have SCMP_ACT_KILL_PROCESS action (https://github.com/seccomp/libseccomp/issues/96). SCMP_ACT_KILL_PROCESS is preferable to immediately terminate the offending process, rather than having the SIGSYS handler running. Use SECCOMP_GET_ACTION_AVAIL to check availability of kernel support, as libseccomp will fallback on SCMP_ACT_KILL otherwise, and we still prefer SCMP_ACT_TRAP. Signed-off-by: Marc-André Lureau Reviewed-by: Daniel P. Berrangé Acked-by: Eduardo Otubo --- qemu-seccomp.c | 31 ++++++++++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) diff --git a/qemu-seccomp.c b/qemu-seccomp.c index b117a92559..f0c833f3ca 100644 --- a/qemu-seccomp.c +++ b/qemu-seccomp.c @@ -20,6 +20,7 @@ #include #include #include "sysemu/seccomp.h" +#include /* For some architectures (notably ARM) cacheflush is not supported until * libseccomp 2.2.3, but configure enforces that we are using a more recent @@ -107,12 +108,40 @@ static const struct QemuSeccompSyscall blacklist[] = { { SCMP_SYS(sched_get_priority_min), QEMU_SECCOMP_SET_RESOURCECTL }, }; +static inline __attribute__((unused)) int +qemu_seccomp(unsigned int operation, unsigned int flags, void *args) +{ +#ifdef __NR_seccomp + return syscall(__NR_seccomp, operation, flags, args); +#else + errno = ENOSYS; + return -1; +#endif +} + +static uint32_t qemu_seccomp_get_kill_action(void) +{ +#if defined(SECCOMP_GET_ACTION_AVAIL) && defined(SCMP_ACT_KILL_PROCESS) && \ + defined(SECCOMP_RET_KILL_PROCESS) + { + uint32_t action = SECCOMP_RET_KILL_PROCESS; + + if (qemu_seccomp(SECCOMP_GET_ACTION_AVAIL, 0, &action) == 0) { + return SCMP_ACT_KILL_PROCESS; + } + } +#endif + + return SCMP_ACT_TRAP; +} + static int seccomp_start(uint32_t seccomp_opts) { int rc = 0; unsigned int i = 0; scmp_filter_ctx ctx; + uint32_t action = qemu_seccomp_get_kill_action(); ctx = seccomp_init(SCMP_ACT_ALLOW); if (ctx == NULL) { @@ -125,7 +154,7 @@ static int seccomp_start(uint32_t seccomp_opts) continue; } - rc = seccomp_rule_add_array(ctx, SCMP_ACT_TRAP, blacklist[i].num, + rc = seccomp_rule_add_array(ctx, action, blacklist[i].num, blacklist[i].narg, blacklist[i].arg_cmp); if (rc < 0) { goto seccomp_return; -- 2.11.0