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bus: fix capabilities on big-endian

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The kernel provides capabilities as a u32 array, sd-bus uses an u8 array.
This works fine on little-endian as both are encoded the same way.
However, this fails on big-endian if we do not perform sufficient
byte-swapping on each u32 entry.

This patch makes sd-bus use u32, too. We avoid changing any kernel
provided data so we can keep pointing into kdbus pool buffers which
contain u32 arrays.
This commit is contained in:
David Herrmann 2014-12-30 09:09:41 +01:00
parent 34a5d5e526
commit 7d9fcc2bf6
3 changed files with 20 additions and 15 deletions
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29
src/libsystemd/sd-bus/bus-creds.c
View File

@ -20,6 +20,7 @@
***/
#include <stdlib.h>
#include <linux/capability.h>
#include "util.h"
#include "capability.h"
@ -592,11 +593,11 @@ static int has_cap(sd_bus_creds *c, unsigned offset, int capability) {
assert(capability >= 0);
assert(c->capability);
sz = DIV_ROUND_UP(cap_last_cap(), 32U) * 4;
sz = DIV_ROUND_UP(cap_last_cap(), 32U);
if ((unsigned)capability > cap_last_cap())
return 0;
return !!(c->capability[offset * sz + (capability / 8)] & (1 << (capability % 8)));
return !!(c->capability[offset * sz + CAP_TO_INDEX(capability)] & CAP_TO_MASK(capability));
}
_public_ int sd_bus_creds_has_effective_cap(sd_bus_creds *c, int capability) {
@ -641,38 +642,42 @@ _public_ int sd_bus_creds_has_bounding_cap(sd_bus_creds *c, int capability) {
static int parse_caps(sd_bus_creds *c, unsigned offset, const char *p) {
size_t sz, max;
unsigned i;
unsigned i, j;
assert(c);
assert(p);
max = DIV_ROUND_UP(cap_last_cap(), 32U) * 4;
max = DIV_ROUND_UP(cap_last_cap(), 32U);
p += strspn(p, WHITESPACE);
sz = strlen(p);
if (sz % 2 != 0)
if (sz % 8 != 0)
return -EINVAL;
sz /= 2;
sz /= 8;
if (sz > max)
return -EINVAL;
if (!c->capability) {
c->capability = new0(uint8_t, max * 4);
c->capability = new0(uint32_t, max * 4);
if (!c->capability)
return -ENOMEM;
}
for (i = 0; i < sz; i ++) {
int x, y;
uint32_t v = 0;
x = unhexchar(p[i*2]);
y = unhexchar(p[i*2+1]);
for (j = 0; j < 8; ++j) {
int t;
if (x < 0 || y < 0)
t = unhexchar(*p++);
if (t < 0)
return -EINVAL;
c->capability[offset * max + (sz - i - 1)] = (uint8_t) x << 4 | (uint8_t) y;
v = (v << 4) | t;
}
c->capability[offset * max + (sz - i - 1)] = v;
}
return 0;

2
src/libsystemd/sd-bus/bus-creds.h
View File

@ -60,7 +60,7 @@ struct sd_bus_creds {
char *user_unit;
char *slice;
uint8_t *capability;
uint32_t *capability;
uint32_t audit_session_id;
uid_t audit_login_uid;

2
src/libsystemd/sd-bus/bus-kernel.c
View File

@ -680,7 +680,7 @@ static int bus_kernel_make_message(sd_bus *bus, struct kdbus_msg *k) {
goto fail;
}
m->creds.capability = (uint8_t *) d->caps.caps;
m->creds.capability = d->caps.caps;
m->creds.mask |= (SD_BUS_CREDS_EFFECTIVE_CAPS|SD_BUS_CREDS_PERMITTED_CAPS|SD_BUS_CREDS_INHERITABLE_CAPS|SD_BUS_CREDS_BOUNDING_CAPS) & bus->creds_mask;
break;