| Message ID | 80c86614e3b21dda074b81fe9c3866fdbbb7420e.1666769319.git.mprivozn@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] seccomp: Get actual errno value from failed seccomp functions | expand |
On Wed, Oct 26, 2022 at 09:30:24AM +0200, Michal Privoznik wrote: > Upon failure, a libseccomp API returns actual errno value very > rarely. Fortunately, after its commit 34bf78ab (contained in > 2.5.0 release), the SCMP_FLTATR_API_SYSRAWRC attribute can be set > which makes subsequent APIs return true errno on failure. > > This is especially critical when seccomp_load() fails, because > generic -ECANCELED says nothing. > > Signed-off-by: Michal Privoznik <mprivozn@redhat.com> > Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> > --- > > v2 of: > > https://lists.gnu.org/archive/html/qemu-devel/2022-10/msg04509.html > > diff to v1: > - added comment when setting SYSRAWRC attribute per Philippe's > suggestion > > meson.build | 9 +++++++++ > softmmu/qemu-seccomp.c | 13 +++++++++++++ > 2 files changed, 22 insertions(+) Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> With regards, Daniel
On 10/26/22 14:33, Daniel P. Berrangé wrote: > On Wed, Oct 26, 2022 at 09:30:24AM +0200, Michal Privoznik wrote: >> Upon failure, a libseccomp API returns actual errno value very >> rarely. Fortunately, after its commit 34bf78ab (contained in >> 2.5.0 release), the SCMP_FLTATR_API_SYSRAWRC attribute can be set >> which makes subsequent APIs return true errno on failure. >> >> This is especially critical when seccomp_load() fails, because >> generic -ECANCELED says nothing. >> >> Signed-off-by: Michal Privoznik <mprivozn@redhat.com> >> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> >> --- >> >> v2 of: >> >> https://lists.gnu.org/archive/html/qemu-devel/2022-10/msg04509.html >> >> diff to v1: >> - added comment when setting SYSRAWRC attribute per Philippe's >> suggestion >> >> meson.build | 9 +++++++++ >> softmmu/qemu-seccomp.c | 13 +++++++++++++ >> 2 files changed, 22 insertions(+) > > Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Thank you. Can somebody merge this please? I don't have commit access. Michal
On Thu, Oct 27, 2022 at 02:55:02PM +0200, Michal Prívozník wrote: > On 10/26/22 14:33, Daniel P. Berrangé wrote: > > On Wed, Oct 26, 2022 at 09:30:24AM +0200, Michal Privoznik wrote: > >> Upon failure, a libseccomp API returns actual errno value very > >> rarely. Fortunately, after its commit 34bf78ab (contained in > >> 2.5.0 release), the SCMP_FLTATR_API_SYSRAWRC attribute can be set > >> which makes subsequent APIs return true errno on failure. > >> > >> This is especially critical when seccomp_load() fails, because > >> generic -ECANCELED says nothing. > >> > >> Signed-off-by: Michal Privoznik <mprivozn@redhat.com> > >> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> > >> --- > >> > >> v2 of: > >> > >> https://lists.gnu.org/archive/html/qemu-devel/2022-10/msg04509.html > >> > >> diff to v1: > >> - added comment when setting SYSRAWRC attribute per Philippe's > >> suggestion > >> > >> meson.build | 9 +++++++++ > >> softmmu/qemu-seccomp.c | 13 +++++++++++++ > >> 2 files changed, 22 insertions(+) > > > > Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> > > Thank you. Can somebody merge this please? I don't have commit access. I'm seccomp subsystem maintainer and have it queued. With regards, Daniel
diff to v1: - added comment when setting SYSRAWRC attribute per Philippe's suggestion meson.build | 9 +++++++++ softmmu/qemu-seccomp.c | 13 +++++++++++++ 2 files changed, 22 insertions(+) diff --git a/meson.build b/meson.build index b686dfef75..5f114c89d9 100644 --- a/meson.build +++ b/meson.build @@ -636,10 +636,16 @@ if vmnet.found() and not cc.has_header_symbol('vmnet/vmnet.h', endif seccomp = not_found +seccomp_has_sysrawrc = false if not get_option('seccomp').auto() or have_system or have_tools seccomp = dependency('libseccomp', version: '>=2.3.0', required: get_option('seccomp'), method: 'pkg-config', kwargs: static_kwargs) + if seccomp.found() + seccomp_has_sysrawrc = cc.has_header_symbol('seccomp.h', + 'SCMP_FLTATR_API_SYSRAWRC', + dependencies: seccomp) + endif endif libcap_ng = not_found @@ -1849,6 +1855,9 @@ config_host_data.set('CONFIG_RDMA', rdma.found()) config_host_data.set('CONFIG_SDL', sdl.found()) config_host_data.set('CONFIG_SDL_IMAGE', sdl_image.found()) config_host_data.set('CONFIG_SECCOMP', seccomp.found()) +if seccomp.found() + config_host_data.set('CONFIG_SECCOMP_SYSRAWRC', seccomp_has_sysrawrc) +endif config_host_data.set('CONFIG_SNAPPY', snappy.found()) config_host_data.set('CONFIG_TPM', have_tpm) config_host_data.set('CONFIG_USB_LIBUSB', libusb.found()) diff --git a/softmmu/qemu-seccomp.c b/softmmu/qemu-seccomp.c index deaf8a4ef5..d66a2a1226 100644 --- a/softmmu/qemu-seccomp.c +++ b/softmmu/qemu-seccomp.c @@ -312,6 +312,19 @@ static int seccomp_start(uint32_t seccomp_opts, Error **errp) goto seccomp_return; } +#if defined(CONFIG_SECCOMP_SYSRAWRC) + /* + * This must be the first seccomp_attr_set() call to have full + * error propagation from subsequent seccomp APIs. + */ + rc = seccomp_attr_set(ctx, SCMP_FLTATR_API_SYSRAWRC, 1); + if (rc != 0) { + error_setg_errno(errp, -rc, + "failed to set seccomp rawrc attribute"); + goto seccomp_return; + } +#endif + rc = seccomp_attr_set(ctx, SCMP_FLTATR_CTL_TSYNC, 1); if (rc != 0) { error_setg_errno(errp, -rc,