Commit 2b716fa6 authored by Eduardo Otubo's avatar Eduardo Otubo
Browse files

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: default avatarEduardo Otubo <otubo@redhat.com>
parent 1bd6152a

include/sysemu/seccomp.h

+2 −1
Original line number Diff line number Diff line
@@ -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

qemu-options.hx

+10 −2
Original line number Diff line number Diff line
@@ -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,

qemu-seccomp.c

+18 −1
Original line number Diff line number Diff line
@@ -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;

vl.c

+23 −1
Original line number Diff line number Diff line
@@ -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;