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libvirt/src/util/vircgroupv2devices.c
Michal Privoznik 95b9db4ee2 lib: Prefer WITH_* prefix for #if conditionals 
Currently, we are mixing: #if HAVE_BLAH with #if WITH_BLAH.
Things got way better with Pavel's work on meson, but apparently,
mixing these two lead to confusing and easy to miss bugs (see
31fb929eca for instance). While we were forced to use HAVE_
prefix with autotools, we are free to chose our own prefix with
meson and since WITH_ prefix appears to be more popular let's use
it everywhere.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
2020-09-02 10:28:10 +02:00

644 lines
18 KiB
C
Raw Blame History

/*
* vircgroupv2devices.c: methods for cgroups v2 BPF devices
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see
* <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#if WITH_DECL_BPF_CGROUP_DEVICE
# include <fcntl.h>
# include <linux/bpf.h>
# include <sys/stat.h>
# include <sys/syscall.h>
# include <sys/types.h>
#endif /* !WITH_DECL_BPF_CGROUP_DEVICE */
#include "internal.h"
#define LIBVIRT_VIRCGROUPPRIV_H_ALLOW
#include "vircgrouppriv.h"
#include "viralloc.h"
#include "virbpf.h"
#include "vircgroup.h"
#include "vircgroupv2devices.h"
#include "virfile.h"
#include "virlog.h"
VIR_LOG_INIT("util.cgroup");
#define VIR_FROM_THIS VIR_FROM_CGROUP
#if WITH_DECL_BPF_CGROUP_DEVICE
bool
virCgroupV2DevicesAvailable(virCgroupPtr group)
{
VIR_AUTOCLOSE cgroupfd = -1;
unsigned int progCnt = 0;
cgroupfd = open(group->unified.mountPoint, O_RDONLY);
if (cgroupfd < 0) {
VIR_DEBUG("failed to open cgroup '%s'", group->unified.mountPoint);
return false;
}
if (virBPFQueryProg(cgroupfd, 0, BPF_CGROUP_DEVICE, &progCnt, NULL) < 0) {
VIR_DEBUG("failed to query cgroup progs: %s", g_strerror(errno));
return false;
}
return true;
}
/* Steps to get assembly version of devices BPF program:
*
* Save the following program into bpfprog.c, compile it using clang:
*
* clang -O2 -Wall -target bpf -c bpfprog.c -o bpfprog.o
*
* Now you can use llvm-objdump to get the list if instructions:
*
* llvm-objdump -S -no-show-raw-insn bpfprog.o
*
* which can be converted into program using VIR_BPF_* macros.
*
* ----------------------------------------------------------------------------
* #include <linux/bpf.h>
* #include <linux/version.h>
*
* #define SEC(NAME) __attribute__((section(NAME), used))
*
* struct bpf_map_def {
* unsigned int type;
* unsigned int key_size;
* unsigned int value_size;
* unsigned int max_entries;
* unsigned int map_flags;
* unsigned int inner_map_idx;
* unsigned int numa_node;
* };
*
* static void *(*bpf_map_lookup_elem)(void *map, void *key) =
* (void *) BPF_FUNC_map_lookup_elem;
*
* struct bpf_map_def SEC("maps") devices = {
* .type = BPF_MAP_TYPE_HASH,
* .key_size = sizeof(__u64),
* .value_size = sizeof(__u32),
* .max_entries = 65,
* };
*
* SEC("cgroup/dev") int
* bpf_libvirt_cgroup_device(struct bpf_cgroup_dev_ctx *ctx)
* {
* __u64 key = ((__u64)ctx->major << 32) | ctx->minor;
* __u32 *val = 0;
*
* val = bpf_map_lookup_elem(&devices, &key);
* if (val && (ctx->access_type & *val) == ctx->access_type)
* return 1;
*
* key = ((__u64)ctx->major << 32) | 0xffffffff;
* val = bpf_map_lookup_elem(&devices, &key);
* if (val && (ctx->access_type & *val) == ctx->access_type)
* return 1;
*
* key = 0xffffffff00000000 | ctx->minor;
* val = bpf_map_lookup_elem(&devices, &key);
* if (val && (ctx->access_type & *val) == ctx->access_type)
* return 1;
*
* key = 0xffffffffffffffff;
* val = bpf_map_lookup_elem(&devices, &key);
* if (val && (ctx->access_type & *val) == ctx->access_type)
* return 1;
*
* return 0;
* }
*
* char _license[] SEC("license") = "GPL";
* __u32 _version SEC("version") = LINUX_VERSION_CODE;
* ----------------------------------------------------------------------------
* */
static int
virCgroupV2DevicesLoadProg(int mapfd)
{
struct bpf_insn prog[] = {
/* 0: r6 = r1 */
VIR_BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
/* 1: r1 = *(u32 *)(r6 + 8) */
VIR_BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6, 8),
/* 2: r2 = *(u32 *)(r6 + 4) */
VIR_BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_6, 4),
/* 3: r2 <<= 32 */
VIR_BPF_ALU64_IMM(BPF_LSH, BPF_REG_2, 32),
/* 4: r2 |= r1 */
VIR_BPF_ALU64_REG(BPF_OR, BPF_REG_2, BPF_REG_1),
/* 5: *(u64 *)(r10 - 8) = r2 */
VIR_BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_2, -8),
/* 6: r2 = r10 */
VIR_BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
/* 7: r2 += -8 */
VIR_BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
/* 8: r1 = 0 ll */
VIR_BPF_LD_MAP_FD(BPF_REG_1, mapfd),
/* 10: call 1 */
VIR_BPF_CALL_INSN(BPF_FUNC_map_lookup_elem),
/* 11: r1 = r0 */
VIR_BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
/* 12: if r1 == 0 goto +5 <LBB0_2> */
VIR_BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 5),
/* 13: r0 = 1 */
VIR_BPF_MOV64_IMM(BPF_REG_0, 1),
/* 14: r2 = *(u32 *)(r6 + 0) */
VIR_BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_6, 0),
/* 15: r1 = *(u32 *)(r1 + 0) */
VIR_BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_1, 0),
/* 16: r1 &= r2 */
VIR_BPF_ALU64_REG(BPF_AND, BPF_REG_1, BPF_REG_2),
/* 17: if r1 == r2 goto +50 <LBB0_9> */
VIR_BPF_JMP_REG(BPF_JEQ, BPF_REG_1, BPF_REG_2, 50),
/* LBB0_2: */
/* 18: r1 = *(u32 *)(r6 + 4) */
VIR_BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6, 4),
/* 19: r1 <<= 32 */
VIR_BPF_ALU64_IMM(BPF_LSH, BPF_REG_1, 32),
/* 20: r2 = 4294967295 ll */
VIR_BPF_LD_IMM64(BPF_REG_2, 0xffffffff),
/* 22: r1 |= r2 */
VIR_BPF_ALU64_REG(BPF_OR, BPF_REG_1, BPF_REG_2),
/* 23: *(u64 *)(r10 - 8) = r1 */
VIR_BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1, -8),
/* 24: r2 = r10 */
VIR_BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
/* 25: r2 += -8 */
VIR_BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
/* 26: r1 = 0 ll */
VIR_BPF_LD_MAP_FD(BPF_REG_1, mapfd),
/* 28: call 1 */
VIR_BPF_CALL_INSN(BPF_FUNC_map_lookup_elem),
/* 29: r1 = r0 */
VIR_BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
/* 30: if r1 == 0 goto +5 <LBB0_4> */
VIR_BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 5),
/* 31: r0 = 1 */
VIR_BPF_MOV64_IMM(BPF_REG_0, 1),
/* 32: r2 = *(u32 *)(r6 + 0) */
VIR_BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_6, 0),
/* 33: r1 = *(u32 *)(r1 + 0) */
VIR_BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_1, 0),
/* 34: r1 &= r2 */
VIR_BPF_ALU64_REG(BPF_AND, BPF_REG_1, BPF_REG_2),
/* 35: if r1 == r2 goto +32 <LBB0_9> */
VIR_BPF_JMP_REG(BPF_JEQ, BPF_REG_1, BPF_REG_2, 32),
/* LBB0_4: */
/* 36: r1 = *(u32 *)(r6 + 8) */
VIR_BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6, 8),
/* 37: r2 = -4294967296 ll */
VIR_BPF_LD_IMM64(BPF_REG_2, 0xffffffff00000000),
/* 39: r1 |= r2 */
VIR_BPF_ALU64_REG(BPF_OR, BPF_REG_1, BPF_REG_2),
/* 40: *(u64 *)(r10 - 8) = r1 */
VIR_BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1, -8),
/* 41: r2 = r10 */
VIR_BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
/* 42: r2 += -8 */
VIR_BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
/* 43: r1 = 0 ll */
VIR_BPF_LD_MAP_FD(BPF_REG_1, mapfd),
/* 45: call 1 */
VIR_BPF_CALL_INSN(BPF_FUNC_map_lookup_elem),
/* 46: r1 = r0 */
VIR_BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
/* 47: if r1 == 0 goto +5 <LBB0_6> */
VIR_BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 5),
/* 48: r0 = 1 */
VIR_BPF_MOV64_IMM(BPF_REG_0, 1),
/* 49: r2 = *(u32 *)(r6 + 0) */
VIR_BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_6, 0),
/* 50: r1 = *(u32 *)(r1 + 0) */
VIR_BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_1, 0),
/* 51: r1 &= r2 */
VIR_BPF_ALU64_REG(BPF_AND, BPF_REG_1, BPF_REG_2),
/* 52: if r1 == r2 goto +15 <LBB0_9> */
VIR_BPF_JMP_REG(BPF_JEQ, BPF_REG_1, BPF_REG_2, 15),
/* LBB0_6: */
/* 53: r1 = -1 */
VIR_BPF_MOV64_IMM(BPF_REG_1, -1),
/* 54: *(u64 *)(r10 - 8) = r1 */
VIR_BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1, -8),
/* 55: r2 = r10 */
VIR_BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
/* 56: r2 += -8 */
VIR_BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
/* 57: r1 = 0 ll */
VIR_BPF_LD_MAP_FD(BPF_REG_1, mapfd),
/* 59: call 1 */
VIR_BPF_CALL_INSN(BPF_FUNC_map_lookup_elem),
/* 60: r1 = r0 */
VIR_BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
/* 61: if r1 == 0 goto +5 <LBB0_8> */
VIR_BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 5),
/* 62: r0 = 1 */
VIR_BPF_MOV64_IMM(BPF_REG_0, 1),
/* 63: r2 = *(u32 *)(r6 + 0) */
VIR_BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_6, 0),
/* 64: r1 = *(u32 *)(r1 + 0) */
VIR_BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_1, 0),
/* 65: r1 &= r2 */
VIR_BPF_ALU64_REG(BPF_AND, BPF_REG_1, BPF_REG_2),
/* 66: if r1 == r2 goto +1 <LBB0_9> */
VIR_BPF_JMP_REG(BPF_JEQ, BPF_REG_1, BPF_REG_2, 1),
/* LBB0_8: */
/* 67: r0 = 0 */
VIR_BPF_MOV64_IMM(BPF_REG_0, 0),
/* LBB0_9: */
/* 68: exit */
VIR_BPF_EXIT_INSN(),
};
return virBPFLoadProg(prog, BPF_PROG_TYPE_CGROUP_DEVICE, G_N_ELEMENTS(prog));
}
static int
virCgroupV2DevicesAttachProg(virCgroupPtr group,
int mapfd,
size_t max)
{
int ret = -1;
VIR_AUTOCLOSE progfd = -1;
VIR_AUTOCLOSE cgroupfd = -1;
g_autofree char *path = NULL;
if (virCgroupPathOfController(group, VIR_CGROUP_CONTROLLER_DEVICES,
NULL, &path) < 0) {
goto cleanup;
}
progfd = virCgroupV2DevicesLoadProg(mapfd);
if (progfd < 0) {
virReportSystemError(errno, "%s", _("failed to load cgroup BPF prog"));
goto cleanup;
}
cgroupfd = open(path, O_RDONLY);
if (cgroupfd < 0) {
virReportSystemError(errno, _("unable to open '%s'"), path);
goto cleanup;
}
if (virBPFAttachProg(progfd, cgroupfd, BPF_CGROUP_DEVICE) < 0) {
virReportSystemError(errno, "%s", _("failed to attach cgroup BPF prog"));
goto cleanup;
}
if (group->unified.devices.progfd > 0) {
VIR_DEBUG("Closing existing program that was replaced by new one.");
VIR_FORCE_CLOSE(group->unified.devices.progfd);
}
if (group->unified.devices.mapfd > 0) {
VIR_DEBUG("Closing existing map that was replaced by new one.");
VIR_FORCE_CLOSE(group->unified.devices.mapfd);
}
group->unified.devices.progfd = progfd;
group->unified.devices.mapfd = mapfd;
group->unified.devices.max = max;
progfd = -1;
mapfd = -1;
ret = 0;
cleanup:
VIR_FORCE_CLOSE(mapfd);
return ret;
}
static int
virCgroupV2DevicesCountMapEntries(int mapfd)
{
int ret = 0;
int rc;
uint64_t key = 0;
uint64_t prevKey = 0;
while ((rc = virBPFGetNextElem(mapfd, &prevKey, &key)) == 0) {
ret++;
prevKey = key;
}
if (rc < 0 && errno != ENOENT)
return -1;
return ret;
}
# define MAX_PROG_IDS 10
int
virCgroupV2DevicesDetectProg(virCgroupPtr group)
{
g_autofree char *path = NULL;
VIR_AUTOCLOSE cgroupfd = -1;
unsigned int progcnt = 0;
unsigned int progids[MAX_PROG_IDS] = { 0 };
int progfd = -1;
int mapfd = -1;
int nitems = -1;
struct bpf_prog_info progInfo = { 0 };
struct bpf_map_info mapInfo = { 0 };
g_autofree unsigned int *mapIDs = NULL;
if (group->unified.devices.progfd > 0 && group->unified.devices.mapfd > 0)
return 0;
if (virCgroupPathOfController(group, VIR_CGROUP_CONTROLLER_DEVICES,
NULL, &path) < 0) {
return -1;
}
cgroupfd = open(path, O_RDONLY);
if (cgroupfd < 0) {
virReportSystemError(errno, _("unable to open '%s'"), path);
return -1;
}
if (virBPFQueryProg(cgroupfd, MAX_PROG_IDS, BPF_CGROUP_DEVICE,
&progcnt, progids) < 0) {
virReportSystemError(errno, "%s", _("unable to query cgroup BPF progs"));
return -1;
}
if (progcnt == 0)
return 0;
/* No need to have alternate code, this function will not be called
* if compiled with old kernel. */
progfd = virBPFGetProg(progids[0]);
if (progfd < 0) {
virReportSystemError(errno, "%s", _("failed to get cgroup BPF prog FD"));
return -1;
}
if (virBPFGetProgInfo(progfd, &progInfo, &mapIDs) < 0) {
virReportSystemError(errno, "%s", _("failed to get cgroup BPF prog info"));
return -1;
}
if (progInfo.nr_map_ids == 0) {
virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
_("no map for cgroup BPF prog"));
return -1;
}
mapfd = virBPFGetMap(mapIDs[0]);
if (mapfd < 0) {
virReportSystemError(errno, "%s", _("failed to get cgroup BPF map FD"));
return -1;
}
if (virBPFGetMapInfo(mapfd, &mapInfo) < 0) {
virReportSystemError(errno, "%s", _("failed to get cgroup BPF map info"));
return -1;
}
nitems = virCgroupV2DevicesCountMapEntries(mapfd);
if (nitems < 0) {
virReportSystemError(errno, "%s", _("failed to count cgroup BPF map items"));
return -1;
}
group->unified.devices.progfd = progfd;
group->unified.devices.mapfd = mapfd;
group->unified.devices.max = mapInfo.max_entries;
group->unified.devices.count = nitems;
return 0;
}
# define VIR_CGROUP_V2_INITIAL_BPF_MAP_SIZE 64
static int
virCgroupV2DevicesCreateMap(size_t size)
{
int mapfd = virBPFCreateMap(BPF_MAP_TYPE_HASH, sizeof(uint64_t),
sizeof(uint32_t), size);
if (mapfd < 0) {
virReportSystemError(errno, "%s",
_("failed to initialize device BPF map"));
return -1;
}
return mapfd;
}
static int
virCgroupV2DevicesReallocMap(int mapfd,
size_t size)
{
uint64_t key = 0;
uint64_t prevKey = 0;
int rc;
int ret = -1;
VIR_AUTOCLOSE newmapfd = virCgroupV2DevicesCreateMap(size);
VIR_DEBUG("realloc devices map mapfd:%d, size:%zu", mapfd, size);
if (newmapfd < 0)
return -1;
while ((rc = virBPFGetNextElem(mapfd, &prevKey, &key)) == 0) {
uint32_t val = 0;
if (virBPFLookupElem(mapfd, &key, &val) < 0) {
virReportSystemError(errno, "%s",
_("failed to lookup device in old map"));
return -1;
}
if (virBPFUpdateElem(newmapfd, &key, &val) < 0) {
virReportSystemError(errno, "%s",
_("failed to add device into new map"));
return -1;
}
prevKey = key;
}
if (rc < 0 && errno != ENOENT) {
virReportSystemError(errno, "%s",
_("failed to copy all device rules"));
return -1;
}
ret = newmapfd;
newmapfd = -1;
return ret;
}
int
virCgroupV2DevicesCreateProg(virCgroupPtr group)
{
int mapfd = -1;
if (group->unified.devices.progfd > 0 && group->unified.devices.mapfd > 0)
return 0;
mapfd = virCgroupV2DevicesCreateMap(VIR_CGROUP_V2_INITIAL_BPF_MAP_SIZE);
if (mapfd < 0)
return -1;
return virCgroupV2DevicesAttachProg(group, mapfd,
VIR_CGROUP_V2_INITIAL_BPF_MAP_SIZE);
}
int
virCgroupV2DevicesPrepareProg(virCgroupPtr group)
{
if (virCgroupV2DevicesDetectProg(group) < 0)
return -1;
if (virCgroupV2DevicesCreateProg(group) < 0)
return -1;
if (group->unified.devices.count >= group->unified.devices.max) {
size_t max = group->unified.devices.max * 2;
int newmapfd = virCgroupV2DevicesReallocMap(group->unified.devices.mapfd,
max);
if (newmapfd < 0)
return -1;
if (virCgroupV2DevicesAttachProg(group, newmapfd, max) < 0)
return -1;
}
return 0;
}
int
virCgroupV2DevicesRemoveProg(virCgroupPtr group)
{
if (virCgroupV2DevicesDetectProg(group) < 0)
return -1;
if (group->unified.devices.progfd <= 0 && group->unified.devices.mapfd <= 0)
return 0;
if (group->unified.devices.mapfd >= 0)
VIR_FORCE_CLOSE(group->unified.devices.mapfd);
if (group->unified.devices.progfd >= 0)
VIR_FORCE_CLOSE(group->unified.devices.progfd);
return 0;
}
uint32_t
virCgroupV2DevicesGetPerms(int perms,
char type)
{
uint32_t ret = 0;
if (perms & VIR_CGROUP_DEVICE_MKNOD)
ret |= BPF_DEVCG_ACC_MKNOD << 16;
if (perms & VIR_CGROUP_DEVICE_READ)
ret |= BPF_DEVCG_ACC_READ << 16;
if (perms & VIR_CGROUP_DEVICE_WRITE)
ret |= BPF_DEVCG_ACC_WRITE << 16;
if (type == 'b')
ret |= BPF_DEVCG_DEV_BLOCK;
else if (type == 'c')
ret |= BPF_DEVCG_DEV_CHAR;
else
ret |= BPF_DEVCG_DEV_BLOCK | BPF_DEVCG_DEV_CHAR;
return ret;
}
#else /* !WITH_DECL_BPF_CGROUP_DEVICE */
bool
virCgroupV2DevicesAvailable(virCgroupPtr group G_GNUC_UNUSED)
{
return false;
}
int
virCgroupV2DevicesDetectProg(virCgroupPtr group G_GNUC_UNUSED)
{
virReportSystemError(ENOSYS, "%s",
_("cgroups v2 BPF devices not supported "
"with this kernel"));
return -1;
}
int
virCgroupV2DevicesCreateProg(virCgroupPtr group G_GNUC_UNUSED)
{
virReportSystemError(ENOSYS, "%s",
_("cgroups v2 BPF devices not supported "
"with this kernel"));
return -1;
}
int
virCgroupV2DevicesPrepareProg(virCgroupPtr group G_GNUC_UNUSED)
{
virReportSystemError(ENOSYS, "%s",
_("cgroups v2 BPF devices not supported "
"with this kernel"));
return -1;
}
int
virCgroupV2DevicesRemoveProg(virCgroupPtr group G_GNUC_UNUSED)
{
return 0;
}
uint32_t
virCgroupV2DevicesGetPerms(int perms G_GNUC_UNUSED,
char type G_GNUC_UNUSED)
{
return 0;
}
#endif /* !WITH_DECL_BPF_CGROUP_DEVICE */
uint64_t
virCgroupV2DevicesGetKey(int major,
int minor)
{
return (uint64_t)major << 32 | ((uint64_t)minor & 0x00000000ffffffff);
}
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