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Unverified Commit babd8f1d by Christian Brauner
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seccomp: handle arch inversion

This commit deals with different kernel and userspace layouts and nesting. Here are three examples: 1. 64bit kernel and 64bit userspace running 32bit containers 2. 64bit kernel and 32bit userspace running 64bit containers 3. 64bit kernel and 64bit userspace running 32bit containers running 64bit containers Two things to lookout for: 1. The compat arch that is detected might have already been present in the main context. So check that it actually hasn't been and only then add it. 2. The contexts don't need merging if the architectures are the same and also can't be. With these changes I can run all crazy/weird combinations with proper seccomp isolation. Closes #654. Link: https://bugs.chromium.org/p/chromium/issues/detail?id=832366Reported-by: 's avatarChirantan Ekbote <chirantan@chromium.org> Reported-by: 's avatarSonny Rao <sonnyrao@chromium.org> Signed-off-by: 's avatarChristian Brauner <christian.brauner@ubuntu.com>
parent 19e75fa0
Showing with 32 additions and 16 deletions
src/lxc/seccomp.c
......@@ -370,17 +370,21 @@ scmp_filter_ctx get_new_ctx(enum lxc_hostarch_t n_arch, uint32_t default_policy_
WARN("Failed to turn on seccomp nop-skip, continuing");
}
#endif
ret = seccomp_arch_add(ctx, arch);
if (ret != 0) {
ERROR("Seccomp error %d (%s) adding arch: %d", ret,
strerror(-ret), (int)n_arch);
seccomp_release(ctx);
return NULL;
}
if (seccomp_arch_remove(ctx, SCMP_ARCH_NATIVE) != 0) {
ERROR("Seccomp error removing native arch");
seccomp_release(ctx);
return NULL;
if (seccomp_arch_exist(ctx, arch) == -EEXIST) {
ret = seccomp_arch_add(ctx, arch);
if (ret != 0) {
ERROR("Seccomp error %d (%s) adding arch: %d", ret,
strerror(-ret), (int)n_arch);
seccomp_release(ctx);
return NULL;
}
if (seccomp_arch_remove(ctx, SCMP_ARCH_NATIVE) != 0) {
ERROR("Seccomp error removing native arch");
seccomp_release(ctx);
return NULL;
}
}
return ctx;
......@@ -772,11 +776,23 @@ static int parse_config_v2(FILE *f, char *line, struct lxc_conf *conf)
}
if (compat_ctx[0]) {
INFO("Merging in the compat Seccomp ctx into the main one");
if (seccomp_merge(conf->seccomp_ctx, compat_ctx[0]) != 0 ||
(compat_ctx[1] != NULL && seccomp_merge(conf->seccomp_ctx, compat_ctx[1]) != 0)) {
ERROR("Error merging compat Seccomp contexts");
goto bad;
INFO("Merging compat seccomp contexts into main context");
if (compat_arch[0] != native_arch && compat_arch[0] != seccomp_arch_native()) {
ret = seccomp_merge(conf->seccomp_ctx, compat_ctx[0]);
if (ret < 0) {
ERROR("Failed to merge first compat seccomp context into main context");
goto bad;
}
TRACE("Merged first compat seccomp context into main context");
}
if (compat_arch[1] && compat_arch[1] != native_arch && compat_arch[1] != seccomp_arch_native()) {
ret = seccomp_merge(conf->seccomp_ctx, compat_ctx[1]);
if (ret < 0) {
ERROR("Failed to merge first compat seccomp context into main context");
goto bad;
}
TRACE("Merged second compat seccomp context into main context");
}
}
......
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