Change the change_process_uid() function so that it takes its input as parameters instead of relying on static global variables. Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; --- os-posix.c | 83 +++++++++++++++++++++++++----------------------------- 1 file changed, 39 insertions(+), 44 deletions(-) diff --git a/os-posix.c b/os-posix.c index 7cd662098e..5a127feee2 100644 --- a/os-posix.c +++ b/os-posix.c @@ -42,13 +42,9 @@ #include <sys/prctl.h> #endif -/* - * Must set all three of these at once. - * Legal combinations are unset by name by uid - */ -static struct passwd *user_pwd; /* NULL non-NULL NULL */ -static uid_t user_uid = (uid_t)-1; /* -1 -1 >=0 */ -static gid_t user_gid = (gid_t)-1; /* -1 -1 >=0 */ +static char *user_name; +static uid_t user_uid = (uid_t)-1; +static gid_t user_gid = (gid_t)-1; static const char *chroot_dir; static int daemonize; @@ -100,7 +96,8 @@ void os_set_proc_name(const char *s) } -static bool os_parse_runas_uid_gid(const char *optarg) +static bool os_parse_runas_uid_gid(const char *optarg, + uid_t *runas_uid, gid_t *runas_gid) { unsigned long lv; const char *ep; @@ -120,9 +117,8 @@ static bool os_parse_runas_uid_gid(const char *optarg) return false; } - user_pwd = NULL; - user_uid = got_uid; - user_gid = got_gid; + *runas_uid = got_uid; + *runas_gid = got_gid; return true; } @@ -132,13 +128,18 @@ static bool os_parse_runas_uid_gid(const char *optarg) */ int os_parse_cmd_args(int index, const char *optarg) { + struct passwd *user_pwd; + switch (index) { case QEMU_OPTION_runas: user_pwd = getpwnam(optarg); if (user_pwd) { - user_uid = -1; - user_gid = -1; - } else if (!os_parse_runas_uid_gid(optarg)) { + user_uid = user_pwd->pw_uid; + user_gid = user_pwd->pw_gid; + user_name = g_strdup(user_pwd->pw_name); + } else if (!os_parse_runas_uid_gid(optarg, + &user_uid, + &user_gid)) { error_report("User \"%s\" doesn't exist" " (and is not <uid>:<gid>)", optarg); @@ -158,41 +159,33 @@ int os_parse_cmd_args(int index, const char *optarg) return 0; } -static void change_process_uid(void) +static void change_process_uid(uid_t uid, gid_t gid, const char *name) { - assert((user_uid == (uid_t)-1) || user_pwd == NULL); - assert((user_uid == (uid_t)-1) == - (user_gid == (gid_t)-1)); - - if (user_pwd || user_uid != (uid_t)-1) { - gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid; - uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid; - if (setgid(intended_gid) < 0) { - error_report("Failed to setgid(%d)", intended_gid); - exit(1); - } - if (user_pwd) { - if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) { - error_report("Failed to initgroups(\"%s\", %d)", - user_pwd->pw_name, user_pwd->pw_gid); - exit(1); - } - } else { - if (setgroups(1, &user_gid) < 0) { - error_report("Failed to setgroups(1, [%d])", - user_gid); - exit(1); - } - } - if (setuid(intended_uid) < 0) { - error_report("Failed to setuid(%d)", intended_uid); + if (setgid(gid) < 0) { + error_report("Failed to setgid(%d)", gid); + exit(1); + } + if (name) { + if (initgroups(name, gid) < 0) { + error_report("Failed to initgroups(\"%s\", %d)", + name, gid); exit(1); } - if (setuid(0) != -1) { - error_report("Dropping privileges failed"); + } else { + if (setgroups(1, &gid) < 0) { + error_report("Failed to setgroups(1, [%d])", + gid); exit(1); } } + if (setuid(uid) < 0) { + error_report("Failed to setuid(%d)", uid); + exit(1); + } + if (setuid(0) != -1) { + error_report("Dropping privileges failed"); + exit(1); + } } static void change_root(void) @@ -275,7 +268,9 @@ void os_setup_post(void) } change_root(); - change_process_uid(); + if (user_uid != -1 && user_gid != -1) { + change_process_uid(user_uid, user_gid, user_name); + } if (daemonize) { uint8_t status = 0; -- 2.34.1

Change the change_root() function so that it takes its input as parameters instead of relying on static global variables. Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; --- os-posix.c | 23 +++++++++++------------ 1 file changed, 11 insertions(+), 12 deletions(-) diff --git a/os-posix.c b/os-posix.c index 5a127feee2..30da1a1491 100644 --- a/os-posix.c +++ b/os-posix.c @@ -188,19 +188,16 @@ static void change_process_uid(uid_t uid, gid_t gid, const char *name) } } -static void change_root(void) +static void change_root(const char *root) { - if (chroot_dir) { - if (chroot(chroot_dir) < 0) { - error_report("chroot failed"); - exit(1); - } - if (chdir("/")) { - error_report("not able to chdir to /: %s", strerror(errno)); - exit(1); - } + if (chroot(root) < 0) { + error_report("chroot failed"); + exit(1); + } + if (chdir("/")) { + error_report("not able to chdir to /: %s", strerror(errno)); + exit(1); } - } void os_daemonize(void) @@ -267,7 +264,9 @@ void os_setup_post(void) } } - change_root(); + if (chroot_dir) { + change_root(chroot_dir); + } if (user_uid != -1 && user_gid != -1) { change_process_uid(user_uid, user_gid, user_name); } -- 2.34.1

With the future intent to try to move to a fully QAPI driven configuration system, we want to have any current command parsing well isolated from logic that applies the resulting configuration. We also don't want os-posix.c to contain code that is specific to the system emulators, as this file is linked to other binaries too. To satisfy these goals, we move parsing of the -runas, -chroot and -daemonize code out of the os-posix.c helper code, and pass the parsed data into APIs in os-posix.c. As a side benefit the 'os_daemonize()' function now lives upto to its name and will always daemonize, instead of using global state to decide to be a no-op sometimes. Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; --- include/sysemu/os-posix.h | 4 +- include/sysemu/os-win32.h | 1 - os-posix.c | 148 +++++++++++--------------------------- os-win32.c | 9 --- softmmu/vl.c | 76 ++++++++++++++++++-- 5 files changed, 113 insertions(+), 125 deletions(-) diff --git a/include/sysemu/os-posix.h b/include/sysemu/os-posix.h index 2edf33658a..390f3f8396 100644 --- a/include/sysemu/os-posix.h +++ b/include/sysemu/os-posix.h @@ -46,7 +46,9 @@ void os_set_line_buffering(void); void os_set_proc_name(const char *s); void os_setup_signal_handling(void); void os_daemonize(void); -void os_setup_post(void); +void os_setup_post(const char *chroot_dir, + uid_t uid, gid_t gid, + const char *username); int os_mlock(void); #define closesocket(s) close(s) diff --git a/include/sysemu/os-win32.h b/include/sysemu/os-win32.h index 43f569b5c2..4879f8731d 100644 --- a/include/sysemu/os-win32.h +++ b/include/sysemu/os-win32.h @@ -61,7 +61,6 @@ struct tm *localtime_r(const time_t *timep, struct tm *result); static inline void os_setup_signal_handling(void) {} static inline void os_daemonize(void) {} -static inline void os_setup_post(void) {} void os_set_line_buffering(void); static inline void os_set_proc_name(const char *dummy) {} diff --git a/os-posix.c b/os-posix.c index 30da1a1491..f598a52a4f 100644 --- a/os-posix.c +++ b/os-posix.c @@ -42,11 +42,6 @@ #include <sys/prctl.h> #endif -static char *user_name; -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; @@ -96,69 +91,6 @@ void os_set_proc_name(const char *s) } -static bool os_parse_runas_uid_gid(const char *optarg, - uid_t *runas_uid, gid_t *runas_gid) -{ - unsigned long lv; - const char *ep; - uid_t got_uid; - gid_t got_gid; - int rc; - - rc = qemu_strtoul(optarg, &ep, 0, &lv); - got_uid = lv; /* overflow here is ID in C99 */ - if (rc || *ep != ':' || got_uid != lv || got_uid == (uid_t)-1) { - return false; - } - - rc = qemu_strtoul(ep + 1, 0, 0, &lv); - got_gid = lv; /* overflow here is ID in C99 */ - if (rc || got_gid != lv || got_gid == (gid_t)-1) { - return false; - } - - *runas_uid = got_uid; - *runas_gid = got_gid; - return true; -} - -/* - * Parse OS specific command line options. - * return 0 if option handled, -1 otherwise - */ -int os_parse_cmd_args(int index, const char *optarg) -{ - struct passwd *user_pwd; - - switch (index) { - case QEMU_OPTION_runas: - user_pwd = getpwnam(optarg); - if (user_pwd) { - user_uid = user_pwd->pw_uid; - user_gid = user_pwd->pw_gid; - user_name = g_strdup(user_pwd->pw_name); - } else if (!os_parse_runas_uid_gid(optarg, - &user_uid, - &user_gid)) { - error_report("User \"%s\" doesn't exist" - " (and is not <uid>:<gid>)", - optarg); - exit(1); - } - break; - case QEMU_OPTION_chroot: - chroot_dir = optarg; - break; - case QEMU_OPTION_daemonize: - daemonize = 1; - break; - default: - return -1; - } - - return 0; -} - static void change_process_uid(uid_t uid, gid_t gid, const char *name) { if (setgid(gid) < 0) { @@ -202,54 +134,56 @@ static void change_root(const char *root) void os_daemonize(void) { - if (daemonize) { - pid_t pid; - int fds[2]; + pid_t pid; + int fds[2]; - if (pipe(fds) == -1) { - exit(1); - } + if (pipe(fds) == -1) { + exit(1); + } - pid = fork(); - if (pid > 0) { - uint8_t status; - ssize_t len; + pid = fork(); + if (pid > 0) { + uint8_t status; + ssize_t len; - close(fds[1]); + close(fds[1]); - do { - len = read(fds[0], &status, 1); - } while (len < 0 && errno == EINTR); + do { + len = read(fds[0], &status, 1); + } while (len < 0 && errno == EINTR); - /* only exit successfully if our child actually wrote - * a one-byte zero to our pipe, upon successful init */ - exit(len == 1 && status == 0 ? 0 : 1); + /* only exit successfully if our child actually wrote + * a one-byte zero to our pipe, upon successful init */ + exit(len == 1 && status == 0 ? 0 : 1); - } else if (pid < 0) { - exit(1); - } + } else if (pid < 0) { + exit(1); + } - close(fds[0]); - daemon_pipe = fds[1]; - qemu_set_cloexec(daemon_pipe); + close(fds[0]); + daemon_pipe = fds[1]; + qemu_set_cloexec(daemon_pipe); - setsid(); + setsid(); - pid = fork(); - if (pid > 0) { + pid = fork(); + if (pid > 0) { exit(0); - } else if (pid < 0) { - exit(1); - } - umask(027); - - signal(SIGTSTP, SIG_IGN); - signal(SIGTTOU, SIG_IGN); - signal(SIGTTIN, SIG_IGN); + } else if (pid < 0) { + exit(1); } + umask(027); + + signal(SIGTSTP, SIG_IGN); + signal(SIGTTOU, SIG_IGN); + signal(SIGTTIN, SIG_IGN); + + daemonize = true; } -void os_setup_post(void) +void os_setup_post(const char *root_dir, + uid_t runas_uid, gid_t runas_gid, + const char *runas_name) { int fd = 0; @@ -264,11 +198,11 @@ void os_setup_post(void) } } - if (chroot_dir) { - change_root(chroot_dir); + if (root_dir != NULL) { + change_root(root_dir); } - if (user_uid != -1 && user_gid != -1) { - change_process_uid(user_uid, user_gid, user_name); + if (runas_uid != -1 && runas_gid != -1) { + change_process_uid(runas_uid, runas_gid, runas_name); } if (daemonize) { diff --git a/os-win32.c b/os-win32.c index e31c921983..6f21b57841 100644 --- a/os-win32.c +++ b/os-win32.c @@ -61,12 +61,3 @@ void os_set_line_buffering(void) setbuf(stdout, NULL); setbuf(stderr, NULL); } - -/* - * Parse OS specific command line options. - * return 0 if option handled, -1 otherwise - */ -int os_parse_cmd_args(int index, const char *optarg) -{ - return -1; -} diff --git a/softmmu/vl.c b/softmmu/vl.c index 1fe028800f..cdf27b6027 100644 --- a/softmmu/vl.c +++ b/softmmu/vl.c @@ -2602,11 +2602,13 @@ static void qemu_process_help_options(void) } } -static void qemu_maybe_daemonize(const char *pid_file) +static void qemu_maybe_daemonize(bool daemonize, const char *pid_file) { Error *err = NULL; - os_daemonize(); + if (daemonize) { + os_daemonize(); + } rcu_disable_atfork(); if (pid_file && !qemu_write_pidfile(pid_file, &err)) { @@ -2768,6 +2770,35 @@ void qmp_x_exit_preconfig(Error **errp) } } +#ifndef WIN32 +static bool os_parse_runas_uid_gid(const char *optarg, + uid_t *runas_uid, + gid_t *runas_gid) +{ + unsigned long lv; + const char *ep; + uid_t got_uid; + gid_t got_gid; + int rc; + + rc = qemu_strtoul(optarg, &ep, 0, &lv); + got_uid = lv; /* overflow here is ID in C99 */ + if (rc || *ep != ':' || got_uid != lv || got_uid == (uid_t)-1) { + return false; + } + + rc = qemu_strtoul(ep + 1, 0, 0, &lv); + got_gid = lv; /* overflow here is ID in C99 */ + if (rc || got_gid != lv || got_gid == (gid_t)-1) { + return false; + } + + *runas_gid = got_gid; + *runas_uid = got_uid; + return true; +} +#endif /* !WIN32 */ + void qemu_init(int argc, char **argv, char **envp) { QemuOpts *opts; @@ -2778,6 +2809,14 @@ void qemu_init(int argc, char **argv, char **envp) MachineClass *machine_class; bool userconfig = true; FILE *vmstate_dump_file = NULL; + bool daemonize = false; +#ifndef WIN32 + struct passwd *pwd; + uid_t runas_uid = -1; + gid_t runas_gid = -1; + g_autofree char *runas_name = NULL; + const char *chroot_dir = NULL; +#endif /* !WIN32 */ qemu_add_opts(&qemu_drive_opts); qemu_add_drive_opts(&qemu_legacy_drive_opts); @@ -3659,11 +3698,32 @@ void qemu_init(int argc, char **argv, char **envp) case QEMU_OPTION_nouserconfig: /* Nothing to be parsed here. Especially, do not error out below. */ break; - default: - if (os_parse_cmd_args(popt->index, optarg)) { - error_report("Option not supported in this build"); +#ifndef WIN32 + case QEMU_OPTION_runas: + pwd = getpwnam(optarg); + if (pwd) { + runas_uid = pwd->pw_uid; + runas_gid = pwd->pw_gid; + runas_name = g_strdup(pwd->pw_name); + } else if (!os_parse_runas_uid_gid(optarg, + &runas_uid, + &runas_gid)) { + error_report("User \"%s\" doesn't exist" + " (and is not <uid>:<gid>)", + optarg); exit(1); } + break; + case QEMU_OPTION_chroot: + chroot_dir = optarg; + break; + case QEMU_OPTION_daemonize: + daemonize = 1; + break; +#endif /* !WIN32 */ + default: + error_report("Option not supported in this build"); + exit(1); } } } @@ -3683,7 +3743,7 @@ void qemu_init(int argc, char **argv, char **envp) qemu_process_early_options(); qemu_process_help_options(); - qemu_maybe_daemonize(pid_file); + qemu_maybe_daemonize(daemonize, pid_file); /* * The trace backend must be initialized after daemonizing. @@ -3778,6 +3838,8 @@ void qemu_init(int argc, char **argv, char **envp) } qemu_init_displays(); accel_setup_post(current_machine); - os_setup_post(); +#ifndef WIN32 + os_setup_post(chroot_dir, runas_uid, runas_gid, runas_name); +#endif /* !WIN32 */ resume_mux_open(); } -- 2.34.1

On Fri, Mar 04, 2022 at 02:54:54PM +0000, Daniel P. Berrangé wrote: up to Yay. Eww, indeed. Looking forward to it. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org