diff options
| author | Lennart Poettering <lennart@poettering.net> | 2016-06-10 18:04:02 +0200 |
|---|---|---|
| committer | Lennart Poettering <lennart@poettering.net> | 2016-06-13 16:25:54 +0200 |
| commit | 54a17e01de048a2275f8861b211f10d11e56407d (patch) | |
| tree | 34e569f8eb22469cabf1d4052c8e9cc1772f4fc7 | |
| parent | 4e069746fe0de1f60bd1b75c113b0f40ffe86736 (diff) | |
nspawn: lock down system call filter a bit
Let's block access to the kernel keyring and a number of obsolete system calls.
Also, update list of syscalls that may alter the system clock, and do raw IO
access. Filter ptrace() if CAP_SYS_PTRACE is not passed to the container and
acct() if CAP_SYS_PACCT is not passed.
This also changes things so that kexec(), some profiling calls, the swap calls
and quotactl() is never available to containers, not even if CAP_SYS_ADMIN is
passed. After all we currently permit CAP_SYS_ADMIN to containers by default,
but these calls should not be available, even then.
| -rw-r--r-- | src/nspawn/nspawn-seccomp.c | 78 |
1 files changed, 67 insertions, 11 deletions
diff --git a/src/nspawn/nspawn-seccomp.c b/src/nspawn/nspawn-seccomp.c index 2d145b68a7..54db1b47f8 100644 --- a/src/nspawn/nspawn-seccomp.c +++ b/src/nspawn/nspawn-seccomp.c @@ -44,20 +44,76 @@ static int seccomp_add_default_syscall_filter(scmp_filter_ctx ctx, uint64_t capability; int syscall_num; } blacklist[] = { - { CAP_SYS_RAWIO, SCMP_SYS(iopl) }, - { CAP_SYS_RAWIO, SCMP_SYS(ioperm) }, - { CAP_SYS_BOOT, SCMP_SYS(kexec_load) }, - { CAP_SYS_ADMIN, SCMP_SYS(swapon) }, - { CAP_SYS_ADMIN, SCMP_SYS(swapoff) }, - { CAP_SYS_ADMIN, SCMP_SYS(open_by_handle_at) }, - { CAP_SYS_MODULE, SCMP_SYS(init_module) }, - { CAP_SYS_MODULE, SCMP_SYS(finit_module) }, - { CAP_SYS_MODULE, SCMP_SYS(delete_module) }, - { CAP_SYSLOG, SCMP_SYS(syslog) }, + { 0, SCMP_SYS(_sysctl) }, /* obsolete syscall */ + { 0, SCMP_SYS(add_key) }, /* keyring is not namespaced */ + { 0, SCMP_SYS(afs_syscall) }, /* obsolete syscall */ + { 0, SCMP_SYS(bdflush) }, +#ifdef __NR_bpf + { 0, SCMP_SYS(bpf) }, +#endif + { 0, SCMP_SYS(break) }, /* obsolete syscall */ + { 0, SCMP_SYS(create_module) }, /* obsolete syscall */ + { 0, SCMP_SYS(ftime) }, /* obsolete syscall */ + { 0, SCMP_SYS(get_kernel_syms) }, /* obsolete syscall */ + { 0, SCMP_SYS(getpmsg) }, /* obsolete syscall */ + { 0, SCMP_SYS(gtty) }, /* obsolete syscall */ +#ifdef __NR_kexec_file_load + { 0, SCMP_SYS(kexec_file_load) }, +#endif + { 0, SCMP_SYS(kexec_load) }, + { 0, SCMP_SYS(keyctl) }, /* keyring is not namespaced */ + { 0, SCMP_SYS(lock) }, /* obsolete syscall */ + { 0, SCMP_SYS(lookup_dcookie) }, + { 0, SCMP_SYS(mpx) }, /* obsolete syscall */ + { 0, SCMP_SYS(nfsservctl) }, /* obsolete syscall */ + { 0, SCMP_SYS(open_by_handle_at) }, + { 0, SCMP_SYS(perf_event_open) }, + { 0, SCMP_SYS(prof) }, /* obsolete syscall */ + { 0, SCMP_SYS(profil) }, /* obsolete syscall */ + { 0, SCMP_SYS(putpmsg) }, /* obsolete syscall */ + { 0, SCMP_SYS(query_module) }, /* obsolete syscall */ + { 0, SCMP_SYS(quotactl) }, + { 0, SCMP_SYS(request_key) }, /* keyring is not namespaced */ + { 0, SCMP_SYS(security) }, /* obsolete syscall */ + { 0, SCMP_SYS(sgetmask) }, /* obsolete syscall */ + { 0, SCMP_SYS(ssetmask) }, /* obsolete syscall */ + { 0, SCMP_SYS(stty) }, /* obsolete syscall */ + { 0, SCMP_SYS(swapoff) }, + { 0, SCMP_SYS(swapon) }, + { 0, SCMP_SYS(sysfs) }, /* obsolete syscall */ + { 0, SCMP_SYS(tuxcall) }, /* obsolete syscall */ + { 0, SCMP_SYS(ulimit) }, /* obsolete syscall */ + { 0, SCMP_SYS(uselib) }, /* obsolete syscall */ + { 0, SCMP_SYS(ustat) }, /* obsolete syscall */ + { 0, SCMP_SYS(vserver) }, /* obsolete syscall */ + { CAP_SYSLOG, SCMP_SYS(syslog) }, + { CAP_SYS_MODULE, SCMP_SYS(delete_module) }, + { CAP_SYS_MODULE, SCMP_SYS(finit_module) }, + { CAP_SYS_MODULE, SCMP_SYS(init_module) }, + { CAP_SYS_PACCT, SCMP_SYS(acct) }, + { CAP_SYS_PTRACE, SCMP_SYS(process_vm_readv) }, + { CAP_SYS_PTRACE, SCMP_SYS(process_vm_writev) }, + { CAP_SYS_PTRACE, SCMP_SYS(ptrace) }, + { CAP_SYS_RAWIO, SCMP_SYS(ioperm) }, + { CAP_SYS_RAWIO, SCMP_SYS(iopl) }, + { CAP_SYS_RAWIO, SCMP_SYS(pciconfig_iobase) }, + { CAP_SYS_RAWIO, SCMP_SYS(pciconfig_read) }, + { CAP_SYS_RAWIO, SCMP_SYS(pciconfig_write) }, +#ifdef __NR_s390_pci_mmio_read + { CAP_SYS_RAWIO, SCMP_SYS(s390_pci_mmio_read) }, +#endif +#ifdef __NR_s390_pci_mmio_write + { CAP_SYS_RAWIO, SCMP_SYS(s390_pci_mmio_write) }, +#endif + { CAP_SYS_TIME, SCMP_SYS(adjtimex) }, + { CAP_SYS_TIME, SCMP_SYS(clock_adjtime) }, + { CAP_SYS_TIME, SCMP_SYS(clock_settime) }, + { CAP_SYS_TIME, SCMP_SYS(settimeofday) }, + { CAP_SYS_TIME, SCMP_SYS(stime) }, }; for (i = 0; i < ELEMENTSOF(blacklist); i++) { - if (cap_list_retain & (1ULL << blacklist[i].capability)) + if (blacklist[i].capability != 0 && (cap_list_retain & (1ULL << blacklist[i].capability))) continue; r = seccomp_rule_add(ctx, SCMP_ACT_ERRNO(EPERM), blacklist[i].syscall_num, 0); |