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[Qemu-devel] [PATCH RFC 6/6] os-posix: Provide new -runasid option
From: |
Ian Jackson |
Subject: |
[Qemu-devel] [PATCH RFC 6/6] os-posix: Provide new -runasid option |
Date: |
Fri, 15 Sep 2017 19:09:59 +0100 |
This allows the caller to specify a uid and gid to use, even if there
is no corresponding password entry. This will be useful in certain
Xen configurations.
Signed-off-by: Ian Jackson <address@hidden>
---
os-posix.c | 30 ++++++++++++++++++++++++++----
qemu-options.hx | 12 ++++++++++++
2 files changed, 38 insertions(+), 4 deletions(-)
diff --git a/os-posix.c b/os-posix.c
index 92e9d85..b88995e 100644
--- a/os-posix.c
+++ b/os-posix.c
@@ -43,6 +43,8 @@
#endif
static struct passwd *user_pwd;
+static uid_t user_uid = (uid_t)-1;
+static gid_t user_gid = (gid_t)-1;
static const char *chroot_dir;
static int daemonize;
static int daemon_pipe;
@@ -134,6 +136,8 @@ void os_set_proc_name(const char *s)
*/
void os_parse_cmd_args(int index, const char *optarg)
{
+ unsigned long lv;
+ char *ep;
switch (index) {
#ifdef CONFIG_SLIRP
case QEMU_OPTION_smb:
@@ -150,6 +154,22 @@ void os_parse_cmd_args(int index, const char *optarg)
exit(1);
}
break;
+ case QEMU_OPTION_runasid:
+ errno = 0;
+ lv = strtoul(optarg, &ep, 0);
+ if (errno || *ep != '.' || (user_uid = lv) != lv
+ || (user_uid == (uid_t)-1)) {
+ fprintf(stderr, "Could not obtain uid from \"%s\"", optarg);
+ exit(1);
+ }
+ errno = 0;
+ lv = strtoul(ep+1, &ep, 0);
+ if (errno || *ep || (user_gid = lv) != lv
+ || (user_gid == (gid_t)-1)) {
+ fprintf(stderr ,"Could not obtain gid from \"%s\"", optarg);
+ exit(1);
+ }
+ break;
case QEMU_OPTION_chroot:
chroot_dir = optarg;
break;
@@ -166,17 +186,19 @@ void os_parse_cmd_args(int index, const char *optarg)
static void change_process_uid(void)
{
- if (user_pwd) {
- if (setgid(user_pwd->pw_gid) < 0) {
+ if (user_pwd || user_uid != (uid_t)-1) {
+ if (setgid(user_pwd ? user_pwd->pw_gid : user_gid) < 0) {
fprintf(stderr, "Failed to setgid(%d)\n", user_pwd->pw_gid);
exit(1);
}
- if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) {
+ if ((user_pwd
+ ? initgroups(user_pwd->pw_name, user_pwd->pw_gid)
+ : setgroups(1, &user_gid)) < 0) {
fprintf(stderr, "Failed to initgroups(\"%s\", %d)\n",
user_pwd->pw_name, user_pwd->pw_gid);
exit(1);
}
- if (setuid(user_pwd->pw_uid) < 0) {
+ if (setuid(user_pwd ? user_pwd->pw_uid : user_gid) < 0) {
fprintf(stderr, "Failed to setuid(%d)\n", user_pwd->pw_uid);
exit(1);
}
diff --git a/qemu-options.hx b/qemu-options.hx
index 9f6e2ad..34a5329 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -3968,6 +3968,18 @@ Immediately before starting guest execution, drop root
privileges, switching
to the specified user.
ETEXI
+#ifndef _WIN32
+DEF("runasid", HAS_ARG, QEMU_OPTION_runasid, \
+ "-runasid uid.gid change to numeric uid and gid just before starting
the VM\n",
+ QEMU_ARCH_ALL)
+#endif
+STEXI
address@hidden -runasid @address@hidden
address@hidden -runasid
+Immediately before starting guest execution, drop root privileges, switching
+to the specified uid and gid.
+ETEXI
+
DEF("prom-env", HAS_ARG, QEMU_OPTION_prom_env,
"-prom-env variable=value\n"
" set OpenBIOS nvram variables\n",
--
2.1.4