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seccomp: add resourcecontrol argument to command line

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This patch adds [,resourcecontrol=deny] to `-sandbox on' option. It
blacklists all process affinity and scheduler priority system calls to
avoid any bigger of the process.

Signed-off-by: Eduardo Otubo <otubo@redhat.com>
This commit is contained in:
Eduardo Otubo 2017-03-13 22:18:51 +01:00
parent 995a226f88
commit 24f8cdc572
4 changed files with 34 additions and 3 deletions
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1
include/sysemu/seccomp.h
View File

@ -19,6 +19,7 @@
#define QEMU_SECCOMP_SET_OBSOLETE (1 << 1)
#define QEMU_SECCOMP_SET_PRIVILEGED (1 << 2)
#define QEMU_SECCOMP_SET_SPAWN (1 << 3)
#define QEMU_SECCOMP_SET_RESOURCECTL (1 << 4)
#include <seccomp.h>

9
qemu-options.hx
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@ -4018,7 +4018,7 @@ ETEXI
DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
"-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \
" [,spawn=allow|deny]\n" \
" [,spawn=allow|deny][,resourcecontrol=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" \
@ -4028,10 +4028,11 @@ DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
" The value 'children' will deny set*uid|gid system calls for\n" \
" main QEMU process but will allow forks and execves to run unprivileged\n" \
" use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \
" blacklisting *fork and execve\n",
" blacklisting *fork and execve\n" \
" use 'resourcecontrol' to disable process affinity and schedular priority\n",
QEMU_ARCH_ALL)
STEXI
@item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}][,spawn=@var{string}]
@item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}][,spawn=@var{string}][,resourcecontrol=@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'.
@ -4042,6 +4043,8 @@ Enable Obsolete system calls
Disable set*uid|gid system calls
@item spawn=@var{string}
Disable *fork and execve
@item resourcecontrol=@var{string}
Disable process affinity and schedular priority
@end table
ETEXI

11
qemu-seccomp.c
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@ -82,6 +82,17 @@ static const struct QemuSeccompSyscall blacklist[] = {
{ SCMP_SYS(fork), QEMU_SECCOMP_SET_SPAWN },
{ SCMP_SYS(vfork), QEMU_SECCOMP_SET_SPAWN },
{ SCMP_SYS(execve), QEMU_SECCOMP_SET_SPAWN },
/* resource control */
{ SCMP_SYS(getpriority), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(setpriority), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_setparam), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_getparam), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_setscheduler), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_getscheduler), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_setaffinity), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_getaffinity), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_get_priority_max), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_get_priority_min), QEMU_SECCOMP_SET_RESOURCECTL },
};

16
vl.c
View File

@ -284,6 +284,10 @@ static QemuOptsList qemu_sandbox_opts = {
.name = "spawn",
.type = QEMU_OPT_STRING,
},
{
.name = "resourcecontrol",
.type = QEMU_OPT_STRING,
},
{ /* end of list */ }
},
};
@ -1099,6 +1103,18 @@ static int parse_sandbox(void *opaque, QemuOpts *opts, Error **errp)
}
}
value = qemu_opt_get(opts, "resourcecontrol");
if (value) {
if (g_str_equal(value, "deny")) {
seccomp_opts |= QEMU_SECCOMP_SET_RESOURCECTL;
} else if (g_str_equal(value, "allow")) {
/* default value */
} else {
error_report("invalid argument for resourcecontrol");
return -1;
}
}
if (seccomp_start(seccomp_opts) < 0) {
error_report("failed to install seccomp syscall filter "
"in the kernel");