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bus: only accept kdbus creds if they are valid

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This allows userspace to fake kdbus creds via struct ucred in the proxy,
without making the recieving side choke on the missing fields of the
kdbus struct, more precisel pid_starttime and tid
This commit is contained in:
Lennart Poettering 2013-12-24 16:20:47 +01:00
parent eff0527098
commit 2dc9970bed
2 changed files with 30 additions and 7 deletions
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16
src/libsystemd-bus/bus-control.c
View file

@ -407,17 +407,25 @@ static int bus_get_owner_kdbus(
switch (item->type) {
case KDBUS_ITEM_CREDS:
m = (SD_BUS_CREDS_UID | SD_BUS_CREDS_GID | SD_BUS_CREDS_PID |
SD_BUS_CREDS_TID | SD_BUS_CREDS_PID_STARTTIME) & mask;
m = (SD_BUS_CREDS_UID | SD_BUS_CREDS_GID | SD_BUS_CREDS_PID) & mask;
if (m) {
c->uid = item->creds.uid;
c->pid = item->creds.pid;
c->gid = item->creds.gid;
c->tid = item->creds.tid;
c->pid_starttime = item->creds.starttime;
c->mask |= m;
}
if (mask & SD_BUS_CREDS_TID && item->creds.tid > 0) {
c->tid = item->creds.tid;
c->mask |= SD_BUS_CREDS_TID;
}
if (mask & SD_BUS_CREDS_PID_STARTTIME && item->creds.starttime > 0) {
c->pid_starttime = item->creds.starttime;
c->mask |= SD_BUS_CREDS_PID_STARTTIME;
}
break;
case KDBUS_ITEM_PID_COMM:

21
src/libsystemd-bus/bus-kernel.c
View file

@ -793,12 +793,27 @@ static int bus_kernel_make_message(sd_bus *bus, struct kdbus_msg *k) {
}
case KDBUS_ITEM_CREDS:
m->creds.pid_starttime = d->creds.starttime / NSEC_PER_USEC;
/* UID/GID/PID are always valid */
m->creds.uid = d->creds.uid;
m->creds.gid = d->creds.gid;
m->creds.pid = d->creds.pid;
m->creds.tid = d->creds.tid;
m->creds.mask |= (SD_BUS_CREDS_UID|SD_BUS_CREDS_GID|SD_BUS_CREDS_PID|SD_BUS_CREDS_PID_STARTTIME|SD_BUS_CREDS_TID) & bus->creds_mask;
m->creds.mask |= (SD_BUS_CREDS_UID|SD_BUS_CREDS_GID|SD_BUS_CREDS_PID) & bus->creds_mask;
/* The PID starttime/TID might be missing
* however, when the data is faked by some
* data bus proxy and it lacks that
* information about the real client since
* SO_PEERCRED is used for that */
if (d->creds.starttime > 0) {
m->creds.pid_starttime = d->creds.starttime / NSEC_PER_USEC;
m->creds.mask |= SD_BUS_CREDS_PID_STARTTIME & bus->creds_mask;
}
if (d->creds.tid > 0) {
m->creds.tid = d->creds.tid;
m->creds.mask |= SD_BUS_CREDS_TID & bus->creds_mask;
}
break;
case KDBUS_ITEM_TIMESTAMP: