Re: [libvirt] libvirt? qemu change that mmaps ELF files breaks libvirt svirt handling for os.kernel

On 04.10.19 14:13, Paolo Bonzini wrote: > On 04/10/19 14:03, Christian Borntraeger wrote: >> Stefano, Paolo, >> >> I have an interesting fail in QEMU >> >> 2019-10-04T12:00:32.675188Z qemu-system-s390x: GLib: g_mapped_file_unref: assertion 'file != NULL' failed >> that bisected to >> commit 816b9fe450220e19acb91a0ce4a8ade7000648d1 (refs/bisect/bad) >> elf-ops.h: Map into memory the ELF to load >> >> strace tells that I can read the ELF file, but not mmap >> strace: >> 214365 openat(AT_FDCWD, "/var/lib/libvirt/images/test_cpu_timer.elf", O_RDONLY) = 36 >> 214365 read(46, "\177ELF\2\2\1\0\0\0\0\0\0\0\0\0", 16) = 16 >> 214365 lseek(46, 0, SEEK_SET) = 0 >> [...] >> 214365 fstat(46, {st_mode=S_IFREG|0755, st_size=168176, ...}) = 0 >> 214365 mmap(NULL, 168176, PROT_READ|PROT_WRITE, MAP_PRIVATE, 46, 0) = -1 EACCES (Permission denied) >> >> So reading from /var/lib/libvirt/images/test_cpu_timer.elf does work, mmaping does not. >> setenforce 0 makes the problem go away. >> >> This might be more of an issue in libvirt, setting the svirt context too >> restrictive, but I am not too deep into the svirt part of libvirt. >> Reverting the qemu commit makes the problem go away. > > Yes, the policy is too restrictive in my opinion. > > Can you include the output of "audit2allow" and/or "audit2allow -R"? > > Thanks, > > Paolo > require { type unconfined_t; type virt_content_t; type svirt_t; type systemd_tmpfiles_t; type user_home_t; type NetworkManager_t; class file { entrypoint execute ioctl lock map open read write }; class bpf prog_run; } #============= svirt_t ============== allow svirt_t user_home_t:file { entrypoint execute ioctl lock open read write }; #!!!! This avc can be allowed using the boolean 'domain_can_mmap_files'

allow svirt_t virt_content_t:file map;

corecmd_bin_entry_type(svirt_t) userdom_manage_user_home_content_dirs(svirt_t) userdom_map_user_home_files(svirt_t) virt_rw_svirt_image(svirt_t)