From c01ff965b48bb9693dcd77cbc748b5d8676766b0 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Thu, 9 Jul 2015 14:46:20 -0300 Subject: nss-mymachines: map userns users of containers to real user names Given a container "foo", that maps user id $UID to container user, using user namespaces, this NSS module extenstion will now map the $UID to a name "vu-foo-$TUID" for the translated UID $UID. Similar, userns groups are mapped to "vg-foo-$TGID" for translated GIDs of $GID. This simple change should make userns users more discoverable. Also, given that many tools like "adduser" check NSS before allocating a UID, should lower the chance of UID range conflicts between tools. --- src/nss-mymachines/nss-mymachines.c | 320 +++++++++++++++++++++++++++++++++- src/nss-mymachines/nss-mymachines.sym | 4 + 2 files changed, 323 insertions(+), 1 deletion(-) (limited to 'src/nss-mymachines') diff --git a/src/nss-mymachines/nss-mymachines.c b/src/nss-mymachines/nss-mymachines.c index f712033e6c..cdec83d074 100644 --- a/src/nss-mymachines/nss-mymachines.c +++ b/src/nss-mymachines/nss-mymachines.c @@ -28,9 +28,12 @@ #include "util.h" #include "nss-util.h" #include "bus-util.h" +#include "bus-common-errors.h" #include "in-addr-util.h" NSS_GETHOSTBYNAME_PROTOTYPES(mymachines); +NSS_GETPW_PROTOTYPES(mymachines); +NSS_GETGR_PROTOTYPES(mymachines); static int count_addresses(sd_bus_message *m, int af, unsigned *ret) { unsigned c = 0; @@ -380,4 +383,319 @@ fail: return NSS_STATUS_UNAVAIL; } -NSS_GETHOSTBYNAME_FALLBACKS(mymachines) +NSS_GETHOSTBYNAME_FALLBACKS(mymachines); + +enum nss_status _nss_mymachines_getpwnam_r( + const char *name, + struct passwd *pwd, + char *buffer, size_t buflen, + int *errnop) { + + _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL; + _cleanup_bus_message_unref_ sd_bus_message* reply = NULL; + _cleanup_bus_flush_close_unref_ sd_bus *bus = NULL; + const char *p, *e, *machine; + uint32_t mapped; + uid_t uid; + size_t l; + int r; + + assert(name); + assert(pwd); + + p = startswith(name, "vu-"); + if (!p) + goto not_found; + + e = strrchr(p, '-'); + if (!e || e == p) + goto not_found; + + r = parse_uid(e + 1, &uid); + if (r < 0) + goto not_found; + + machine = strndupa(p, e - p); + if (!machine_name_is_valid(machine)) + goto not_found; + + r = sd_bus_open_system(&bus); + if (r < 0) + goto fail; + + r = sd_bus_call_method(bus, + "org.freedesktop.machine1", + "/org/freedesktop/machine1", + "org.freedesktop.machine1.Manager", + "MapFromMachineUser", + &error, + &reply, + "su", + machine, (uint32_t) uid); + if (r < 0) { + if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_USER_MAPPING)) + goto not_found; + + goto fail; + } + + r = sd_bus_message_read(reply, "u", &mapped); + if (r < 0) + goto fail; + + l = strlen(name); + if (buflen < l+1) { + *errnop = ENOMEM; + return NSS_STATUS_TRYAGAIN; + } + + memcpy(buffer, name, l+1); + + pwd->pw_name = buffer; + pwd->pw_uid = mapped; + pwd->pw_gid = 65534; /* nobody */ + pwd->pw_gecos = buffer; + pwd->pw_passwd = (char*) "*"; /* locked */ + pwd->pw_dir = (char*) "/"; + pwd->pw_shell = (char*) "/sbin/nologin"; + + *errnop = 0; + return NSS_STATUS_SUCCESS; + +not_found: + *errnop = 0; + return NSS_STATUS_NOTFOUND; + +fail: + *errnop = -r; + return NSS_STATUS_UNAVAIL; +} + +enum nss_status _nss_mymachines_getpwuid_r( + uid_t uid, + struct passwd *pwd, + char *buffer, size_t buflen, + int *errnop) { + + _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL; + _cleanup_bus_message_unref_ sd_bus_message* reply = NULL; + _cleanup_bus_flush_close_unref_ sd_bus *bus = NULL; + const char *machine, *object; + uint32_t mapped; + int r; + + if (UID_IS_INVALID(uid)) { + r = -EINVAL; + goto fail; + } + + /* We consider all uids < 65536 host uids */ + if (uid < 0x10000) + goto not_found; + + r = sd_bus_open_system(&bus); + if (r < 0) + goto fail; + + r = sd_bus_call_method(bus, + "org.freedesktop.machine1", + "/org/freedesktop/machine1", + "org.freedesktop.machine1.Manager", + "MapToMachineUser", + &error, + &reply, + "u", + (uint32_t) uid); + if (r < 0) { + if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_USER_MAPPING)) + goto not_found; + + goto fail; + } + + r = sd_bus_message_read(reply, "sou", &machine, &object, &mapped); + if (r < 0) + goto fail; + + if (snprintf(buffer, buflen, "vu-%s-" UID_FMT, machine, (uid_t) mapped) >= (int) buflen) { + *errnop = ENOMEM; + return NSS_STATUS_TRYAGAIN; + } + + pwd->pw_name = buffer; + pwd->pw_uid = uid; + pwd->pw_gid = 65534; /* nobody */ + pwd->pw_gecos = buffer; + pwd->pw_passwd = (char*) "*"; /* locked */ + pwd->pw_dir = (char*) "/"; + pwd->pw_shell = (char*) "/sbin/nologin"; + + *errnop = 0; + return NSS_STATUS_SUCCESS; + +not_found: + *errnop = 0; + return NSS_STATUS_NOTFOUND; + +fail: + *errnop = -r; + return NSS_STATUS_UNAVAIL; +} + +enum nss_status _nss_mymachines_getgrnam_r( + const char *name, + struct group *gr, + char *buffer, size_t buflen, + int *errnop) { + + _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL; + _cleanup_bus_message_unref_ sd_bus_message* reply = NULL; + _cleanup_bus_flush_close_unref_ sd_bus *bus = NULL; + const char *p, *e, *machine; + uint32_t mapped; + uid_t gid; + size_t l; + int r; + + assert(name); + assert(gr); + + p = startswith(name, "vg-"); + if (!p) + goto not_found; + + e = strrchr(p, '-'); + if (!e || e == p) + goto not_found; + + r = parse_gid(e + 1, &gid); + if (r < 0) + goto not_found; + + machine = strndupa(p, e - p); + if (!machine_name_is_valid(machine)) + goto not_found; + + r = sd_bus_open_system(&bus); + if (r < 0) + goto fail; + + r = sd_bus_call_method(bus, + "org.freedesktop.machine1", + "/org/freedesktop/machine1", + "org.freedesktop.machine1.Manager", + "MapFromMachineGroup", + &error, + &reply, + "su", + machine, (uint32_t) gid); + if (r < 0) { + if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_GROUP_MAPPING)) + goto not_found; + + goto fail; + } + + r = sd_bus_message_read(reply, "u", &mapped); + if (r < 0) + goto fail; + + l = sizeof(char*) + strlen(name) + 1; + if (buflen < l) { + *errnop = ENOMEM; + return NSS_STATUS_TRYAGAIN; + } + + memzero(buffer, sizeof(char*)); + strcpy(buffer + sizeof(char*), name); + + gr->gr_name = buffer + sizeof(char*); + gr->gr_gid = gid; + gr->gr_passwd = (char*) "*"; /* locked */ + gr->gr_mem = (char**) buffer; + + *errnop = 0; + return NSS_STATUS_SUCCESS; + +not_found: + *errnop = 0; + return NSS_STATUS_NOTFOUND; + +fail: + *errnop = -r; + return NSS_STATUS_UNAVAIL; +} + +enum nss_status _nss_mymachines_getgrgid_r( + gid_t gid, + struct group *gr, + char *buffer, size_t buflen, + int *errnop) { + + _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL; + _cleanup_bus_message_unref_ sd_bus_message* reply = NULL; + _cleanup_bus_flush_close_unref_ sd_bus *bus = NULL; + const char *machine, *object; + uint32_t mapped; + int r; + + if (GID_IS_INVALID(gid)) { + r = -EINVAL; + goto fail; + } + + /* We consider all gids < 65536 host gids */ + if (gid < 0x10000) + goto not_found; + + r = sd_bus_open_system(&bus); + if (r < 0) + goto fail; + + r = sd_bus_call_method(bus, + "org.freedesktop.machine1", + "/org/freedesktop/machine1", + "org.freedesktop.machine1.Manager", + "MapToMachineGroup", + &error, + &reply, + "u", + (uint32_t) gid); + if (r < 0) { + if (sd_bus_error_has_name(&error, BUS_ERROR_NO_SUCH_GROUP_MAPPING)) + goto not_found; + + goto fail; + } + + r = sd_bus_message_read(reply, "sou", &machine, &object, &mapped); + if (r < 0) + goto fail; + + if (buflen < sizeof(char*) + 1) { + *errnop = ENOMEM; + return NSS_STATUS_TRYAGAIN; + } + + memzero(buffer, sizeof(char*)); + if (snprintf(buffer + sizeof(char*), buflen - sizeof(char*), "vg-%s-" GID_FMT, machine, (gid_t) mapped) >= (int) buflen) { + *errnop = ENOMEM; + return NSS_STATUS_TRYAGAIN; + } + + gr->gr_name = buffer + sizeof(char*); + gr->gr_gid = gid; + gr->gr_passwd = (char*) "*"; /* locked */ + gr->gr_mem = (char**) buffer; + + *errnop = 0; + return NSS_STATUS_SUCCESS; + +not_found: + *errnop = 0; + return NSS_STATUS_NOTFOUND; + +fail: + *errnop = -r; + return NSS_STATUS_UNAVAIL; +} diff --git a/src/nss-mymachines/nss-mymachines.sym b/src/nss-mymachines/nss-mymachines.sym index f80b51c1aa..0728ac3ba7 100644 --- a/src/nss-mymachines/nss-mymachines.sym +++ b/src/nss-mymachines/nss-mymachines.sym @@ -13,5 +13,9 @@ global: _nss_mymachines_gethostbyname2_r; _nss_mymachines_gethostbyname3_r; _nss_mymachines_gethostbyname4_r; + _nss_mymachines_getpwnam_r; + _nss_mymachines_getpwuid_r; + _nss_mymachines_getgrnam_r; + _nss_mymachines_getgrgid_r; local: *; }; -- cgit v1.2.3-54-g00ecf