| Message ID | b971585976862e52df4c373286104dd0540be8b7.1666699164.git.mprivozn@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | seccomp: Get actual errno value from failed seccomp functions | expand |
Cc'ing Daniel (maintainer) On 25/10/22 13:59, 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> > --- > meson.build | 9 +++++++++ > softmmu/qemu-seccomp.c | 9 +++++++++ > 2 files changed, 18 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..05abf257c4 100644 > --- a/softmmu/qemu-seccomp.c > +++ b/softmmu/qemu-seccomp.c > @@ -312,6 +312,15 @@ static int seccomp_start(uint32_t seccomp_opts, Error **errp) > goto seccomp_return; > } > > +#if defined(CONFIG_SECCOMP_SYSRAWRC) Maybe add some comment here such: /* * This must be the first seccomp_attr_set() call to have full * error propagation. */ > + 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, Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
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..05abf257c4 100644 --- a/softmmu/qemu-seccomp.c +++ b/softmmu/qemu-seccomp.c @@ -312,6 +312,15 @@ static int seccomp_start(uint32_t seccomp_opts, Error **errp) goto seccomp_return; } +#if defined(CONFIG_SECCOMP_SYSRAWRC) + 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,
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> --- meson.build | 9 +++++++++ softmmu/qemu-seccomp.c | 9 +++++++++ 2 files changed, 18 insertions(+)