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authorEduardo Otubo <otubo@redhat.com>2017-03-01 23:17:29 +0100
committerEduardo Otubo <otubo@redhat.com>2017-09-15 10:15:05 +0200
commit2b716fa6d63a183a42b789595c3944f53c0ded7c (patch)
treea460580478014b6b51768ba9c2e407c11fff8875
parent1bd6152ae23549032ef4aca0d3d350512f012f05 (diff)
seccomp: add obsolete argument to command line
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 <otubo@redhat.com>
-rw-r--r--include/sysemu/seccomp.h3
-rw-r--r--qemu-options.hx12
-rw-r--r--qemu-seccomp.c19
-rw-r--r--vl.c24
4 files changed, 53 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 f66613fc71..8a5fbd2ff1 100644
--- a/qemu-seccomp.c
+++ b/qemu-seccomp.c
@@ -55,9 +55,22 @@ static const struct QemuSeccompSyscall blacklist[] = {
{ SCMP_SYS(tuxcall), QEMU_SECCOMP_SET_DEFAULT },
{ SCMP_SYS(ulimit), QEMU_SECCOMP_SET_DEFAULT },
{ SCMP_SYS(vserver), QEMU_SECCOMP_SET_DEFAULT },
+ /* obsolete */
+ { SCMP_SYS(readdir), QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(_sysctl), QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(bdflush), QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(create_module), QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(get_kernel_syms), QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(query_module), QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(sgetmask), QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(ssetmask), QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(sysfs), QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(uselib), QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(ustat), QEMU_SECCOMP_SET_OBSOLETE },
};
-int seccomp_start(void)
+
+int seccomp_start(uint32_t seccomp_opts)
{
int rc = 0;
unsigned int i = 0;
@@ -70,6 +83,10 @@ int seccomp_start(void)
}
for (i = 0; i < ARRAY_SIZE(blacklist); i++) {
+ if (!(seccomp_opts & blacklist[i].set)) {
+ continue;
+ }
+
rc = seccomp_rule_add(ctx, SCMP_ACT_KILL, blacklist[i].num, 0);
if (rc < 0) {
goto seccomp_return;
diff --git a/vl.c b/vl.c
index 76e0b3a946..57c5e93c1a 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 */ }
},
};
@@ -1034,7 +1038,25 @@ 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 = QEMU_SECCOMP_SET_DEFAULT
+ | QEMU_SECCOMP_SET_OBSOLETE;
+ const char *value = NULL;
+
+ value = qemu_opt_get(opts, "obsolete");
+ if (value) {
+ if (g_str_equal(value, "allow")) {
+ seccomp_opts &= ~QEMU_SECCOMP_SET_OBSOLETE;
+ } else if (g_str_equal(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");
+ return -1;
+ }
+ }
+
+ if (seccomp_start(seccomp_opts) < 0) {
error_report("failed to install seccomp syscall filter "
"in the kernel");
return -1;