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authorLennart Poettering <lennart@poettering.net>2016-06-10 18:04:02 +0200
committerLennart Poettering <lennart@poettering.net>2016-06-13 16:25:54 +0200
commit54a17e01de048a2275f8861b211f10d11e56407d (patch)
tree34e569f8eb22469cabf1d4052c8e9cc1772f4fc7
parent4e069746fe0de1f60bd1b75c113b0f40ffe86736 (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.c78
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);