This patch introduces the argument [,obsolete=allow] to the `-sandbox on'
option. It allows Qemu to run safely on old system that still relies on
old system calls.
Signed-off-by: Eduardo Otubo <ot...@redhat.com>
---
include/sysemu/seccomp.h | 3 ++-
qemu-options.hx | 12 ++++++++++--
qemu-seccomp.c | 23 ++++++++++++++++++++++-
vl.c | 22 +++++++++++++++++++++-
4 files changed, 55 insertions(+), 5 deletions(-)
diff --git a/include/sysemu/seccomp.h b/include/sysemu/seccomp.h
index 23b9c3c789..215138a372 100644
--- a/include/sysemu/seccomp.h
+++ b/include/sysemu/seccomp.h
@@ -16,8 +16,9 @@
#define QEMU_SECCOMP_H
#define QEMU_SECCOMP_SET_DEFAULT (1 << 0)
+#define QEMU_SECCOMP_SET_OBSOLETE (1 << 1)
#include <seccomp.h>
-int seccomp_start(void);
+int seccomp_start(uint32_t seccomp_opts);
#endif
diff --git a/qemu-options.hx b/qemu-options.hx
index 9f6e2adfff..72150c6b84 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4017,13 +4017,21 @@ Old param mode (ARM only).
ETEXI
DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
- "-sandbox <arg> Enable seccomp mode 2 system call filter (default
'off').\n",
+ "-sandbox on[,obsolete=allow|deny]\n" \
+ " Enable seccomp mode 2 system call filter (default
'off').\n" \
+ " use 'obsolete' to allow obsolete system calls that are
provided\n" \
+ " by the kernel, but typically no longer used by
modern\n" \
+ " C library implementations.\n",
QEMU_ARCH_ALL)
STEXI
-@item -sandbox @var{arg}
+@item -sandbox @var{arg}[,obsolete=@var{string}]
@findex -sandbox
Enable Seccomp mode 2 system call filter. 'on' will enable syscall filtering
and 'off' will
disable it. The default is 'off'.
+@table @option
+@item obsolete=@var{string}
+Enable Obsolete system calls
+@end table
ETEXI
DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig,
diff --git a/qemu-seccomp.c b/qemu-seccomp.c
index 585de42a97..3e3f15cc08 100644
--- a/qemu-seccomp.c
+++ b/qemu-seccomp.c
@@ -56,9 +56,22 @@ static const struct QemuSeccompSyscall blacklist[] = {
{ SCMP_SYS(tuxcall), 1, QEMU_SECCOMP_SET_DEFAULT },
{ SCMP_SYS(ulimit), 1, QEMU_SECCOMP_SET_DEFAULT },
{ SCMP_SYS(vserver), 1, QEMU_SECCOMP_SET_DEFAULT },
+ /* obsolete */
+ { SCMP_SYS(readdir), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(_sysctl), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(bdflush), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(create_module), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(get_kernel_syms), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(query_module), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(sgetmask), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(ssetmask), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(sysfs), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(uselib), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(ustat), 2, QEMU_SECCOMP_SET_OBSOLETE },
};
-int seccomp_start(void)
+
+int seccomp_start(uint32_t seccomp_opts)
{
int rc = 0;
unsigned int i = 0;
@@ -72,6 +85,14 @@ int seccomp_start(void)
for (i = 0; i < ARRAY_SIZE(blacklist); i++) {
switch (blacklist[i].set) {
+ case QEMU_SECCOMP_SET_OBSOLETE:
+ if (!(seccomp_opts & QEMU_SECCOMP_SET_OBSOLETE)) {
+ goto add_syscall;
+ } else {
+ continue;
+ }
+
+ break;
default:
goto add_syscall;
}
diff --git a/vl.c b/vl.c
index 305531aba8..ca267f9918 100644
--- a/vl.c
+++ b/vl.c
@@ -271,6 +271,10 @@ static QemuOptsList qemu_sandbox_opts = {
.name = "enable",
.type = QEMU_OPT_BOOL,
},
+ {
+ .name = "obsolete",
+ .type = QEMU_OPT_STRING,
+ },
{ /* end of list */ }
},
};
@@ -1032,7 +1036,23 @@ static int parse_sandbox(void *opaque, QemuOpts *opts,
Error **errp)
{
if (qemu_opt_get_bool(opts, "enable", false)) {
#ifdef CONFIG_SECCOMP
- if (seccomp_start() < 0) {
+ uint32_t seccomp_opts = 0x00000;
+ const char *value = NULL;
+
+ value = qemu_opt_get(opts, "obsolete");
+ if (value) {
+ if (strcmp(value, "allow") == 0) {
+ seccomp_opts |= QEMU_SECCOMP_SET_OBSOLETE;
+ } else if (strcmp(value, "deny")) {
+ /* this is the default option, this if is here
+ * to provide a little bit of consistency for
+ * the command line */
+ } else {
+ error_report("invalid argument for obsolete");
+ }
+ }
+
+ if (seccomp_start(seccomp_opts) < 0) {
error_report("failed to install seccomp syscall filter "
"in the kernel");
return -1;
--
2.13.5
