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e92e255285
Instead of always sharing the FDs with the userspace process, only hand over the FDs needed for mmap when required. The idea is that userspace might be able to force the stub into executing an mmap syscall, however, it will not be able to manipulate the control flow sufficiently to have access to an FD that would allow mapping arbitrary memory. Security wise, we need to be sure that only the expected syscalls are executed after the kernel sends FDs through the socket. This is currently not the case, as userspace can trivially jump to the rt_sigreturn syscall instruction to execute any syscall that the stub is permitted to do. With this, it can trick the kernel to send the FD, which in turn allows userspace to freely map any physical memory. As such, this is currently *not* secure. However, in principle the approach should be fine with a more strict SECCOMP filter and a careful review of the stub control flow (as userspace can prepare a stack). With some care, it is likely possible to extend the security model to SMP if desired. Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20250602130052.545733-8-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com> |
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| .. | ||
| skas | ||
| arch.h | ||
| as-layout.h | ||
| common-offsets.h | ||
| elf_user.h | ||
| frame_kern.h | ||
| init.h | ||
| irq_kern.h | ||
| irq_user.h | ||
| kern_util.h | ||
| kern.h | ||
| longjmp.h | ||
| mem_user.h | ||
| mem.h | ||
| os.h | ||
| ptrace_user.h | ||
| registers.h | ||
| sigio.h | ||
| timetravel.h | ||
| um_malloc.h | ||
| user.h | ||