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Re: [Qemu-devel] [PATCH 2/5] seccomp: add obsolete argument to command l
From: |
Thomas Huth |
Subject: |
Re: [Qemu-devel] [PATCH 2/5] seccomp: add obsolete argument to command line |
Date: |
Tue, 14 Mar 2017 13:01:11 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 |
On 14.03.2017 12:32, Eduardo Otubo wrote:
> 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 <address@hidden>
> ---
> include/sysemu/seccomp.h | 4 +++-
> qemu-options.hx | 9 +++++++--
> qemu-seccomp.c | 47 ++++++++++++++++++++++++++++++++++++++++++++++-
> vl.c | 16 +++++++++++++++-
> 4 files changed, 71 insertions(+), 5 deletions(-)
>
> diff --git a/include/sysemu/seccomp.h b/include/sysemu/seccomp.h
> index cfc06008cb..7a7bde246b 100644
> --- a/include/sysemu/seccomp.h
> +++ b/include/sysemu/seccomp.h
> @@ -15,7 +15,9 @@
> #ifndef QEMU_SECCOMP_H
> #define QEMU_SECCOMP_H
>
> +#define OBSOLETE 0x0001
> +
> #include <seccomp.h>
>
> -int seccomp_start(void);
> +int seccomp_start(uint8_t seccomp_opts);
> #endif
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 8dd8ee34a6..1403d0c85f 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -3732,13 +3732,18 @@ 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] Enable seccomp mode 2 system call filter
> (default 'off').\n" \
> + " obsolete: Allow obsolete system calls",
> QEMU_ARCH_ALL)
> STEXI
> address@hidden -sandbox @var{arg}
> address@hidden -sandbox @var{arg}[,address@hidden
> @findex -sandbox
> Enable Seccomp mode 2 system call filter. 'on' will enable syscall filtering
> and 'off' will
> disable it. The default is 'off'.
> address@hidden @option
> address@hidden address@hidden
> +Enable Obsolete system calls
> address@hidden table
> ETEXI
>
> DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig,
> diff --git a/qemu-seccomp.c b/qemu-seccomp.c
> index f8877b07b5..5ef36890da 100644
> --- a/qemu-seccomp.c
> +++ b/qemu-seccomp.c
> @@ -31,6 +31,35 @@ struct QemuSeccompSyscall {
> uint8_t priority;
> };
>
> +static const struct QemuSeccompSyscall obsolete[] = {
> + { SCMP_SYS(readdir), 255 },
> + { SCMP_SYS(_sysctl), 255 },
> + { SCMP_SYS(afs_syscall), 255 },
> + { SCMP_SYS(bdflush), 255 },
> + { SCMP_SYS(break), 255 },
> + { SCMP_SYS(create_module), 255 },
> + { SCMP_SYS(ftime), 255 },
> + { SCMP_SYS(get_kernel_syms), 255 },
> + { SCMP_SYS(getpmsg), 255 },
> + { SCMP_SYS(gtty), 255 },
> + { SCMP_SYS(lock), 255 },
> + { SCMP_SYS(mpx), 255 },
> + { SCMP_SYS(prof), 255 },
> + { SCMP_SYS(profil), 255 },
> + { SCMP_SYS(putpmsg), 255 },
> + { SCMP_SYS(query_module), 255 },
> + { SCMP_SYS(security), 255 },
> + { SCMP_SYS(sgetmask), 255 },
> + { SCMP_SYS(ssetmask), 255 },
> + { SCMP_SYS(stty), 255 },
> + { SCMP_SYS(sysfs), 255 },
> + { SCMP_SYS(tuxcall), 255 },
> + { SCMP_SYS(ulimit), 255 },
> + { SCMP_SYS(uselib), 255 },
> + { SCMP_SYS(ustat), 255 },
> + { SCMP_SYS(vserver), 255 },
> +};
> +
> static const struct QemuSeccompSyscall blacklist[] = {
> { SCMP_SYS(reboot), 255 },
> { SCMP_SYS(swapon), 255 },
> @@ -56,7 +85,20 @@ static const struct QemuSeccompSyscall blacklist[] = {
> { SCMP_SYS(vserver), 255 },
> };
>
> -int seccomp_start(void)
> +static int is_obsolete(int syscall)
> +{
> + unsigned int i = 0;
> +
> + for (i = 0; i < ARRAY_SIZE(obsolete); i++) {
> + if (syscall == obsolete[i].num) {
> + return 1;
> + }
> + }
> +
> + return 0;
> +}
> +
> +int seccomp_start(uint8_t seccomp_opts)
> {
> int rc = 0;
> unsigned int i = 0;
> @@ -69,6 +111,9 @@ int seccomp_start(void)
> }
>
> for (i = 0; i < ARRAY_SIZE(blacklist); i++) {
> + if ((seccomp_opts & OBSOLETE) && is_obsolete(blacklist[i].num)) {
> + 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 1a95500ac7..7b08b3383b 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -269,6 +269,10 @@ static QemuOptsList qemu_sandbox_opts = {
> .name = "enable",
> .type = QEMU_OPT_BOOL,
> },
> + {
> + .name = "obsolete",
> + .type = QEMU_OPT_STRING,
> + },
Since this is basically a boolean switch, could you maybe rather use
"QEMU_OPT_BOOL" here, too (and also in the following patches)? I think
it is also easier for the users to memorize "obsolete=on" instead of
yet-another-parameter-syntax like "obsolete=allow".
Thomas