diff options
| author | Eduardo Otubo <otubo@redhat.com> | 2017-03-13 22:16:01 +0100 |
|---|---|---|
| committer | Eduardo Otubo <otubo@redhat.com> | 2017-09-15 10:15:06 +0200 |
| commit | 995a226f880b807e05240e8752d6ce65679775be (patch) | |
| tree | 52c583395208ab69f6deb0bed685aeb3eefefbe0 | |
| parent | 73a1e647256b09734ce64ef7a6001a0db03f7106 (diff) | |
seccomp: add spawn argument to command line
This patch adds [,spawn=deny] argument to `-sandbox on' option. It
blacklists fork and execve system calls, avoiding Qemu to spawn new
threads or processes.
Signed-off-by: Eduardo Otubo <otubo@redhat.com>
| -rw-r--r-- | include/sysemu/seccomp.h | 1 | ||||
| -rw-r--r-- | qemu-options.hx | 9 | ||||
| -rw-r--r-- | qemu-seccomp.c | 4 | ||||
| -rw-r--r-- | vl.c | 16 |
4 files changed, 28 insertions, 2 deletions
diff --git a/include/sysemu/seccomp.h b/include/sysemu/seccomp.h index 4a9e63c7cd..3ab5fc4f61 100644 --- a/include/sysemu/seccomp.h +++ b/include/sysemu/seccomp.h @@ -18,6 +18,7 @@ #define QEMU_SECCOMP_SET_DEFAULT (1 << 0) #define QEMU_SECCOMP_SET_OBSOLETE (1 << 1) #define QEMU_SECCOMP_SET_PRIVILEGED (1 << 2) +#define QEMU_SECCOMP_SET_SPAWN (1 << 3) #include <seccomp.h> diff --git a/qemu-options.hx b/qemu-options.hx index 5c1b163fb5..2b04b9f170 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -4018,6 +4018,7 @@ ETEXI DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \ "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \ + " [,spawn=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" \ @@ -4025,10 +4026,12 @@ DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \ " use 'elevateprivileges' to allow or deny QEMU process to elevate\n" \ " its privileges by blacklisting all set*uid|gid system calls.\n" \ " 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", + " 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", QEMU_ARCH_ALL) STEXI -@item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}] +@item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}][,spawn=@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'. @@ -4037,6 +4040,8 @@ disable it. The default is 'off'. Enable Obsolete system calls @item elevateprivileges=@var{string} Disable set*uid|gid system calls +@item spawn=@var{string} +Disable *fork and execve @end table ETEXI diff --git a/qemu-seccomp.c b/qemu-seccomp.c index 978d66bd28..f3878a5e29 100644 --- a/qemu-seccomp.c +++ b/qemu-seccomp.c @@ -78,6 +78,10 @@ static const struct QemuSeccompSyscall blacklist[] = { { SCMP_SYS(setresgid), QEMU_SECCOMP_SET_PRIVILEGED }, { SCMP_SYS(setfsuid), QEMU_SECCOMP_SET_PRIVILEGED }, { SCMP_SYS(setfsgid), QEMU_SECCOMP_SET_PRIVILEGED }, + /* spawn */ + { SCMP_SYS(fork), QEMU_SECCOMP_SET_SPAWN }, + { SCMP_SYS(vfork), QEMU_SECCOMP_SET_SPAWN }, + { SCMP_SYS(execve), QEMU_SECCOMP_SET_SPAWN }, }; @@ -280,6 +280,10 @@ static QemuOptsList qemu_sandbox_opts = { .name = "elevateprivileges", .type = QEMU_OPT_STRING, }, + { + .name = "spawn", + .type = QEMU_OPT_STRING, + }, { /* end of list */ } }, }; @@ -1083,6 +1087,18 @@ static int parse_sandbox(void *opaque, QemuOpts *opts, Error **errp) } } + value = qemu_opt_get(opts, "spawn"); + if (value) { + if (g_str_equal(value, "deny")) { + seccomp_opts |= QEMU_SECCOMP_SET_SPAWN; + } else if (g_str_equal(value, "allow")) { + /* default value */ + } else { + error_report("invalid argument for spawn"); + return -1; + } + } + if (seccomp_start(seccomp_opts) < 0) { error_report("failed to install seccomp syscall filter " "in the kernel"); |