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systemd/src/basic/virt.c
Mike Yuan 01184496a2 virt: revert to detect chroot by comparing with / rather than /proc/PID/root 
This partially reverts d6267b9b18

So, arch-chroot currently uses a rather cursed setup:
it sets up a PID namespace, but mounts /proc/ from the outside
into the chroot tree, and then call chroot(2), essentially
making it somewhere between chroot(8) and a full-blown
container. Hence, the PID dirs in /proc/ reveal the outer world.
The offending commit switched chroot detection to compare
/proc/1/root and /proc/OUR_PID/root, exhibiting the faulty behavior
where the mentioned environment now gets deemed to be non-chroot.

Now, this is very much an issue in arch-chroot. However,
if /proc/ is to be properly associated with the pidns,
then we'd treat it as a container and no longer a chroot.
Also, the previous logic feels more readable and more
honestly reported errors in proc_mounted(). Hence I opted
for reverting the change here. Still note that the culprit
(once again :/) lies in the arch-chroot's pidns impl, not
systemd.

Fixes https://gitlab.archlinux.org/archlinux/packaging/packages/systemd/-/issues/54
2025-09-19 13:09:34 +02:00

999 lines
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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#if defined(__i386__) || defined(__x86_64__)
#include <cpuid.h>
#endif
#include <stdlib.h>
#include <threads.h>
#include <unistd.h>
#include "alloc-util.h"
#include "dirent-util.h"
#include "env-util.h"
#include "extract-word.h"
#include "fd-util.h"
#include "fileio.h"
#include "log.h"
#include "namespace-util.h"
#include "parse-util.h"
#include "process-util.h"
#include "stat-util.h"
#include "string-table.h"
#include "string-util.h"
#include "strv.h"
#include "virt.h"
enum {
SMBIOS_VM_BIT_SET,
SMBIOS_VM_BIT_UNSET,
SMBIOS_VM_BIT_UNKNOWN,
};
static Virtualization detect_vm_cpuid(void) {
/* CPUID is an x86 specific interface. */
#if defined(__i386__) || defined(__x86_64__)
static const struct {
const char sig[13];
Virtualization id;
} vm_table[] = {
{ "XenVMMXenVMM", VIRTUALIZATION_XEN },
{ "KVMKVMKVM", VIRTUALIZATION_KVM }, /* qemu with KVM */
{ "Linux KVM Hv", VIRTUALIZATION_KVM }, /* qemu with KVM + HyperV Enlightenments */
{ "TCGTCGTCGTCG", VIRTUALIZATION_QEMU }, /* qemu without KVM */
/* http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1009458 */
{ "VMwareVMware", VIRTUALIZATION_VMWARE },
/* https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs */
{ "Microsoft Hv", VIRTUALIZATION_MICROSOFT },
/* https://wiki.freebsd.org/bhyve */
{ "bhyve bhyve ", VIRTUALIZATION_BHYVE },
{ "QNXQVMBSQG", VIRTUALIZATION_QNX },
/* https://projectacrn.org */
{ "ACRNACRNACRN", VIRTUALIZATION_ACRN },
/* https://www.lockheedmartin.com/en-us/products/Hardened-Security-for-Intel-Processors.html */
{ "SRESRESRESRE", VIRTUALIZATION_SRE },
{ "Apple VZ", VIRTUALIZATION_APPLE },
};
uint32_t eax, ebx, ecx, edx;
bool hypervisor;
/* http://lwn.net/Articles/301888/ */
/* First detect whether there is a hypervisor */
if (__get_cpuid(1, &eax, &ebx, &ecx, &edx) == 0)
return VIRTUALIZATION_NONE;
hypervisor = ecx & 0x80000000U;
if (hypervisor) {
union {
uint32_t sig32[3];
char text[13];
} sig = {};
/* There is a hypervisor, see what it is */
__cpuid(0x40000000U, eax, ebx, ecx, edx);
sig.sig32[0] = ebx;
sig.sig32[1] = ecx;
sig.sig32[2] = edx;
log_debug("Virtualization found, CPUID=%s", sig.text);
FOREACH_ELEMENT(vm, vm_table)
if (memcmp_nn(sig.text, sizeof(sig.text),
vm->sig, sizeof(vm->sig)) == 0)
return vm->id;
log_debug("Unknown virtualization with CPUID=%s. Add to vm_table[]?", sig.text);
return VIRTUALIZATION_VM_OTHER;
}
#endif
log_debug("No virtualization found in CPUID");
return VIRTUALIZATION_NONE;
}
static Virtualization detect_vm_device_tree(void) {
#if defined(__arm__) || defined(__aarch64__) || defined(__powerpc__) || defined(__powerpc64__) || defined(__riscv)
_cleanup_free_ char *hvtype = NULL;
int r;
r = read_one_line_file("/proc/device-tree/hypervisor/compatible", &hvtype);
if (r == -ENOENT) {
if (access("/proc/device-tree/ibm,partition-name", F_OK) == 0 &&
access("/proc/device-tree/hmc-managed?", F_OK) == 0 &&
access("/proc/device-tree/chosen/qemu,graphic-width", F_OK) != 0)
return VIRTUALIZATION_POWERVM;
_cleanup_closedir_ DIR *dir = opendir("/proc/device-tree");
if (!dir) {
if (errno == ENOENT) {
log_debug_errno(errno, "/proc/device-tree/ does not exist");
return VIRTUALIZATION_NONE;
}
return log_debug_errno(errno, "Opening /proc/device-tree/ failed: %m");
}
FOREACH_DIRENT(de, dir, return log_debug_errno(errno, "Failed to enumerate /proc/device-tree/ contents: %m"))
if (strstr(de->d_name, "fw-cfg")) {
log_debug("Virtualization QEMU: \"fw-cfg\" present in /proc/device-tree/%s", de->d_name);
return VIRTUALIZATION_QEMU;
}
_cleanup_free_ char *compat = NULL;
r = read_one_line_file("/proc/device-tree/compatible", &compat);
if (r < 0 && r != -ENOENT)
return log_debug_errno(r, "Failed to read /proc/device-tree/compatible: %m");
if (r >= 0) {
if (streq(compat, "qemu,pseries")) {
log_debug("Virtualization %s found in /proc/device-tree/compatible", compat);
return VIRTUALIZATION_QEMU;
}
if (streq(compat, "linux,dummy-virt")) {
/* https://www.kernel.org/doc/Documentation/devicetree/bindings/arm/linux%2Cdummy-virt.yaml */
log_debug("Generic virtualization %s found in /proc/device-tree/compatible", compat);
return VIRTUALIZATION_VM_OTHER;
}
}
log_debug("No virtualization found in /proc/device-tree/*");
return VIRTUALIZATION_NONE;
} else if (r < 0)
return r;
log_debug("Virtualization %s found in /proc/device-tree/hypervisor/compatible", hvtype);
if (streq(hvtype, "linux,kvm"))
return VIRTUALIZATION_KVM;
else if (strstr(hvtype, "xen"))
return VIRTUALIZATION_XEN;
else if (strstr(hvtype, "vmware"))
return VIRTUALIZATION_VMWARE;
else
return VIRTUALIZATION_VM_OTHER;
#else
log_debug("This platform does not support /proc/device-tree");
return VIRTUALIZATION_NONE;
#endif
}
#if defined(__i386__) || defined(__x86_64__) || defined(__arm__) || defined(__aarch64__) || defined(__loongarch_lp64) || defined(__riscv)
static Virtualization detect_vm_dmi_vendor(void) {
static const char* const dmi_vendors[] = {
"/sys/class/dmi/id/product_name", /* Test this before sys_vendor to detect KVM over QEMU */
"/sys/class/dmi/id/sys_vendor",
"/sys/class/dmi/id/board_vendor",
"/sys/class/dmi/id/bios_vendor",
"/sys/class/dmi/id/product_version", /* For Hyper-V VMs test */
NULL
};
static const struct {
const char *vendor;
Virtualization id;
} dmi_vendor_table[] = {
{ "KVM", VIRTUALIZATION_KVM },
{ "OpenStack", VIRTUALIZATION_KVM }, /* Detect OpenStack instance as KVM in non x86 architecture */
{ "KubeVirt", VIRTUALIZATION_KVM }, /* Detect KubeVirt instance as KVM in non x86 architecture */
{ "Amazon EC2", VIRTUALIZATION_AMAZON },
{ "QEMU", VIRTUALIZATION_QEMU },
{ "VMware", VIRTUALIZATION_VMWARE }, /* https://kb.vmware.com/s/article/1009458 */
{ "VMW", VIRTUALIZATION_VMWARE },
{ "innotek GmbH", VIRTUALIZATION_ORACLE },
{ "VirtualBox", VIRTUALIZATION_ORACLE },
{ "Oracle Corporation", VIRTUALIZATION_ORACLE }, /* Detect VirtualBox on some proprietary systems via the board_vendor */
{ "Xen", VIRTUALIZATION_XEN },
{ "Bochs", VIRTUALIZATION_BOCHS },
{ "Parallels", VIRTUALIZATION_PARALLELS },
/* https://wiki.freebsd.org/bhyve */
{ "BHYVE", VIRTUALIZATION_BHYVE },
{ "Hyper-V", VIRTUALIZATION_MICROSOFT },
{ "Apple Virtualization", VIRTUALIZATION_APPLE },
{ "Google Compute Engine", VIRTUALIZATION_GOOGLE }, /* https://cloud.google.com/run/docs/container-contract#sandbox */
};
int r;
STRV_FOREACH(vendor, dmi_vendors) {
_cleanup_free_ char *s = NULL;
r = read_one_line_file(*vendor, &s);
if (r < 0) {
if (r == -ENOENT)
continue;
return r;
}
FOREACH_ELEMENT(dmi_vendor, dmi_vendor_table)
if (startswith(s, dmi_vendor->vendor)) {
log_debug("Virtualization %s found in DMI (%s)", s, *vendor);
return dmi_vendor->id;
}
}
log_debug("No virtualization found in DMI vendor table.");
return VIRTUALIZATION_NONE;
}
static int detect_vm_smbios(void) {
/* The SMBIOS BIOS Characteristics Extension Byte 2 (Section 2.1.2.2 of
* https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.4.0.pdf), specifies that
* the 4th bit being set indicates a VM. The BIOS Characteristics table is exposed via the kernel in
* /sys/firmware/dmi/entries/0-0. Note that in the general case, this bit being unset should not
* imply that the system is running on bare-metal. For example, QEMU 3.1.0 (with or without KVM)
* with SeaBIOS does not set this bit. */
_cleanup_free_ char *s = NULL;
size_t readsize;
int r;
r = read_full_virtual_file("/sys/firmware/dmi/entries/0-0/raw", &s, &readsize);
if (r < 0) {
log_debug_errno(r, "Unable to read /sys/firmware/dmi/entries/0-0/raw, "
"using the virtualization information found in DMI vendor table, ignoring: %m");
return SMBIOS_VM_BIT_UNKNOWN;
}
if (readsize < 20 || s[1] < 20) {
/* The spec indicates that byte 1 contains the size of the table, 0x12 + the number of
* extension bytes. The data we're interested in is in extension byte 2, which would be at
* 0x13. If we didn't read that much data, or if the BIOS indicates that we don't have that
* much data, we don't infer anything from the SMBIOS. */
log_debug("Only read %zu bytes from /sys/firmware/dmi/entries/0-0/raw (expected 20). "
"Using the virtualization information found in DMI vendor table.", readsize);
return SMBIOS_VM_BIT_UNKNOWN;
}
uint8_t byte = (uint8_t) s[19];
if (byte & (1U<<4)) {
log_debug("DMI BIOS Extension table indicates virtualization.");
return SMBIOS_VM_BIT_SET;
}
log_debug("DMI BIOS Extension table does not indicate virtualization.");
return SMBIOS_VM_BIT_UNSET;
}
#endif /* defined(__i386__) || defined(__x86_64__) || defined(__arm__) || defined(__aarch64__) || defined(__loongarch_lp64) */
static Virtualization detect_vm_dmi(void) {
#if defined(__i386__) || defined(__x86_64__) || defined(__arm__) || defined(__aarch64__) || defined(__loongarch_lp64) || defined(__riscv)
int r;
r = detect_vm_dmi_vendor();
/* The DMI vendor tables in /sys/class/dmi/id don't help us distinguish between Amazon EC2
* virtual machines and bare-metal instances, so we need to look at SMBIOS. */
if (r == VIRTUALIZATION_AMAZON) {
switch (detect_vm_smbios()) {
case SMBIOS_VM_BIT_SET:
return VIRTUALIZATION_AMAZON;
case SMBIOS_VM_BIT_UNSET:
return VIRTUALIZATION_NONE;
case SMBIOS_VM_BIT_UNKNOWN: {
/* The DMI information we are after is only accessible to the root user,
* so we fallback to using the product name which is less restricted
* to distinguish metal systems from virtualized instances */
_cleanup_free_ char *s = NULL;
const char *e;
r = read_full_virtual_file("/sys/class/dmi/id/product_name", &s, NULL);
/* In EC2, virtualized is much more common than metal, so if for some reason
* we fail to read the DMI data, assume we are virtualized. */
if (r < 0) {
log_debug_errno(r, "Can't read /sys/class/dmi/id/product_name,"
" assuming virtualized: %m");
return VIRTUALIZATION_AMAZON;
}
e = strstrafter(truncate_nl(s), ".metal");
if (e && IN_SET(*e, 0, '-')) {
log_debug("DMI product name has '.metal', assuming no virtualization");
return VIRTUALIZATION_NONE;
} else
return VIRTUALIZATION_AMAZON;
}
default:
assert_not_reached();
}
}
/* If we haven't identified a VM, but the firmware indicates that there is one, indicate as much. We
* have no further information about what it is. */
if (r == VIRTUALIZATION_NONE && detect_vm_smbios() == SMBIOS_VM_BIT_SET)
return VIRTUALIZATION_VM_OTHER;
return r;
#else
return VIRTUALIZATION_NONE;
#endif
}
#define XENFEAT_dom0 11 /* xen/include/public/features.h */
#define PATH_FEATURES "/sys/hypervisor/properties/features"
/* Returns -errno, or 0 for domU, or 1 for dom0 */
static int detect_vm_xen_dom0(void) {
_cleanup_free_ char *domcap = NULL;
int r;
r = read_one_line_file(PATH_FEATURES, &domcap);
if (r < 0 && r != -ENOENT)
return r;
if (r >= 0) {
unsigned long features;
/* Here, we need to use sscanf() instead of safe_atoul()
* as the string lacks the leading "0x". */
r = sscanf(domcap, "%lx", &features);
if (r == 1) {
r = !!(features & (1U << XENFEAT_dom0));
log_debug("Virtualization XEN, found %s with value %08lx, "
"XENFEAT_dom0 (indicating the 'hardware domain') is%s set.",
PATH_FEATURES, features, r ? "" : " not");
return r;
}
log_debug("Virtualization XEN, found %s, unhandled content '%s'",
PATH_FEATURES, domcap);
}
r = read_one_line_file("/proc/xen/capabilities", &domcap);
if (r == -ENOENT) {
log_debug("Virtualization XEN because /proc/xen/capabilities does not exist");
return 0;
}
if (r < 0)
return r;
for (const char *i = domcap;;) {
_cleanup_free_ char *cap = NULL;
r = extract_first_word(&i, &cap, ",", 0);
if (r < 0)
return r;
if (r == 0) {
log_debug("Virtualization XEN DomU found (/proc/xen/capabilities)");
return 0;
}
if (streq(cap, "control_d")) {
log_debug("Virtualization XEN Dom0 ignored (/proc/xen/capabilities)");
return 1;
}
}
}
static Virtualization detect_vm_xen(void) {
/* The presence of /proc/xen indicates some form of a Xen domain
The check for Dom0 is handled outside this function */
if (access("/proc/xen", F_OK) < 0) {
log_debug("Virtualization XEN not found, /proc/xen does not exist");
return VIRTUALIZATION_NONE;
}
log_debug("Virtualization XEN found (/proc/xen exists)");
return VIRTUALIZATION_XEN;
}
static Virtualization detect_vm_hypervisor(void) {
_cleanup_free_ char *hvtype = NULL;
int r;
r = read_one_line_file("/sys/hypervisor/type", &hvtype);
if (r == -ENOENT)
return VIRTUALIZATION_NONE;
if (r < 0)
return r;
log_debug("Virtualization %s found in /sys/hypervisor/type", hvtype);
if (streq(hvtype, "xen"))
return VIRTUALIZATION_XEN;
else
return VIRTUALIZATION_VM_OTHER;
}
static Virtualization detect_vm_uml(void) {
_cleanup_fclose_ FILE *f = NULL;
int r;
/* Detect User-Mode Linux by reading /proc/cpuinfo */
f = fopen("/proc/cpuinfo", "re");
if (!f) {
if (errno == ENOENT) {
log_debug("/proc/cpuinfo not found, assuming no UML virtualization.");
return VIRTUALIZATION_NONE;
}
return -errno;
}
for (;;) {
_cleanup_free_ char *line = NULL;
const char *t;
r = read_line(f, LONG_LINE_MAX, &line);
if (r < 0)
return r;
if (r == 0)
break;
t = startswith(line, "vendor_id\t: ");
if (t) {
if (startswith(t, "User Mode Linux")) {
log_debug("UML virtualization found in /proc/cpuinfo");
return VIRTUALIZATION_UML;
}
break;
}
}
log_debug("UML virtualization not found in /proc/cpuinfo.");
return VIRTUALIZATION_NONE;
}
static Virtualization detect_vm_zvm(void) {
#if defined(__s390__)
_cleanup_free_ char *t = NULL;
int r;
r = get_proc_field("/proc/sysinfo", "VM00 Control Program", &t);
if (IN_SET(r, -ENOENT, -ENODATA))
return VIRTUALIZATION_NONE;
if (r < 0)
return r;
log_debug("Virtualization %s found in /proc/sysinfo", t);
if (streq(t, "z/VM"))
return VIRTUALIZATION_ZVM;
else
return VIRTUALIZATION_KVM;
#else
log_debug("This platform does not support /proc/sysinfo");
return VIRTUALIZATION_NONE;
#endif
}
/* Returns a short identifier for the various VM implementations */
Virtualization detect_vm(void) {
static thread_local Virtualization cached_found = _VIRTUALIZATION_INVALID;
bool other = false, hyperv = false;
int xen_dom0 = 0;
Virtualization v, dmi;
if (cached_found >= 0)
return cached_found;
/* We have to use the correct order here:
*
* → First, try to detect Oracle Virtualbox, Amazon EC2 Nitro, Parallels, and Google Compute Engine,
* even if they use KVM, as well as Xen, even if it cloaks as Microsoft Hyper-V. Attempt to detect
* UML at this stage too, since it runs as a user-process nested inside other VMs. Also check for
* Xen now, because Xen PV mode does not override CPUID when nested inside another hypervisor.
*
* → Second, try to detect from CPUID. This will report KVM for whatever software is used even if
* info in DMI is overwritten.
*
* → Third, try to detect from DMI. */
dmi = detect_vm_dmi();
if (IN_SET(dmi,
VIRTUALIZATION_ORACLE,
VIRTUALIZATION_XEN,
VIRTUALIZATION_AMAZON,
/* Unable to distinguish a GCE machine from a VM to bare-metal
* for non-x86 architectures due to its necessity for cpuid
* detection, which functions solely on x86 platforms. Report
* as a VM for other architectures. */
#if !defined(__i386__) && !defined(__x86_64__)
VIRTUALIZATION_GOOGLE,
#endif
VIRTUALIZATION_PARALLELS)) {
v = dmi;
goto finish;
}
/* Detect UML */
v = detect_vm_uml();
if (v < 0)
return v;
if (v != VIRTUALIZATION_NONE)
goto finish;
/* Detect Xen */
v = detect_vm_xen();
if (v < 0)
return v;
if (v == VIRTUALIZATION_XEN) {
/* If we are Dom0, then we expect to not report as a VM. However, as we might be nested
* inside another hypervisor which can be detected via the CPUID check, wait to report this
* until after the CPUID check. */
xen_dom0 = detect_vm_xen_dom0();
if (xen_dom0 < 0)
return xen_dom0;
if (xen_dom0 == 0)
goto finish;
} else if (v != VIRTUALIZATION_NONE)
assert_not_reached();
/* Detect from CPUID */
v = detect_vm_cpuid();
if (v < 0)
return v;
if (v == VIRTUALIZATION_MICROSOFT)
/* QEMU sets the CPUID string to hyperv's, in case it provides hyperv enlightenments. Let's
* hence not return Microsoft here but just use the other mechanisms first to make a better
* decision. */
hyperv = true;
else if (v == VIRTUALIZATION_VM_OTHER)
other = true;
else if (v == VIRTUALIZATION_KVM && dmi == VIRTUALIZATION_GOOGLE)
/* The DMI vendor tables in /sys/class/dmi/id don't help us distinguish between GCE
* virtual machines and bare-metal instances, so we need to look at hypervisor. */
return VIRTUALIZATION_GOOGLE;
else if (v != VIRTUALIZATION_NONE)
goto finish;
/* If we are in Dom0 and have not yet finished, finish with the result of detect_vm_cpuid */
if (xen_dom0 > 0)
goto finish;
/* Now, let's get back to DMI */
if (dmi < 0)
return dmi;
if (dmi == VIRTUALIZATION_VM_OTHER)
other = true;
else if (!IN_SET(dmi, VIRTUALIZATION_NONE, VIRTUALIZATION_GOOGLE)) {
/* At this point if GCE has been detected in dmi, do not report as a VM. It should
* be a bare-metal machine */
v = dmi;
goto finish;
}
/* Check high-level hypervisor sysfs file */
v = detect_vm_hypervisor();
if (v < 0)
return v;
if (v == VIRTUALIZATION_VM_OTHER)
other = true;
else if (v != VIRTUALIZATION_NONE)
goto finish;
v = detect_vm_device_tree();
if (v < 0)
return v;
if (v == VIRTUALIZATION_VM_OTHER)
other = true;
else if (v != VIRTUALIZATION_NONE)
goto finish;
v = detect_vm_zvm();
if (v < 0)
return v;
finish:
/* None of the checks above gave us a clear answer, hence let's now use fallback logic: if hyperv
* enlightenments are available but the VMM wasn't recognized as anything yet, it's probably
* Microsoft. */
if (v == VIRTUALIZATION_NONE) {
if (hyperv)
v = VIRTUALIZATION_MICROSOFT;
else if (other)
v = VIRTUALIZATION_VM_OTHER;
}
cached_found = v;
log_debug("Found VM virtualization %s", virtualization_to_string(v));
return v;
}
static const char *const container_table[_VIRTUALIZATION_MAX] = {
[VIRTUALIZATION_LXC] = "lxc",
[VIRTUALIZATION_LXC_LIBVIRT] = "lxc-libvirt",
[VIRTUALIZATION_SYSTEMD_NSPAWN] = "systemd-nspawn",
[VIRTUALIZATION_DOCKER] = "docker",
[VIRTUALIZATION_PODMAN] = "podman",
[VIRTUALIZATION_RKT] = "rkt",
[VIRTUALIZATION_WSL] = "wsl",
[VIRTUALIZATION_PROOT] = "proot",
[VIRTUALIZATION_POUCH] = "pouch",
};
DEFINE_PRIVATE_STRING_TABLE_LOOKUP_FROM_STRING(container, int);
static int running_in_pidns(void) {
int r;
r = namespace_is_init(NAMESPACE_PID);
if (r < 0)
return log_debug_errno(r, "Failed to test if in root PID namespace, ignoring: %m");
return !r;
}
static Virtualization detect_container_files(void) {
static const struct {
const char *file_path;
Virtualization id;
} container_file_table[] = {
/* https://github.com/containers/podman/issues/6192 */
/* https://github.com/containers/podman/issues/3586#issuecomment-661918679 */
{ "/run/.containerenv", VIRTUALIZATION_PODMAN },
/* https://github.com/moby/moby/issues/18355 */
/* Docker must be the last in this table, see below. */
{ "/.dockerenv", VIRTUALIZATION_DOCKER },
};
FOREACH_ELEMENT(file, container_file_table) {
if (access(file->file_path, F_OK) >= 0)
return file->id;
if (errno != ENOENT)
log_debug_errno(errno,
"Checking if %s exists failed, ignoring: %m",
file->file_path);
}
return VIRTUALIZATION_NONE;
}
Virtualization detect_container(void) {
static thread_local Virtualization cached_found = _VIRTUALIZATION_INVALID;
_cleanup_free_ char *m = NULL, *o = NULL, *p = NULL;
const char *e = NULL;
Virtualization v;
int r;
if (cached_found >= 0)
return cached_found;
/* /proc/vz exists in container and outside of the container, /proc/bc only outside of the container. */
if (access("/proc/vz", F_OK) < 0) {
if (errno != ENOENT)
log_debug_errno(errno, "Failed to check if /proc/vz exists, ignoring: %m");
} else if (access("/proc/bc", F_OK) < 0) {
if (errno == ENOENT) {
v = VIRTUALIZATION_OPENVZ;
goto finish;
}
log_debug_errno(errno, "Failed to check if /proc/bc exists, ignoring: %m");
}
/* "Official" way of detecting WSL https://github.com/Microsoft/WSL/issues/423#issuecomment-221627364 */
r = read_one_line_file("/proc/sys/kernel/osrelease", &o);
if (r < 0)
log_debug_errno(r, "Failed to read /proc/sys/kernel/osrelease, ignoring: %m");
else if (strstr(o, "Microsoft") || strstr(o, "WSL")) {
v = VIRTUALIZATION_WSL;
goto finish;
}
/* proot doesn't use PID namespacing, so we can just check if we have a matching tracer for this
* invocation without worrying about it being elsewhere.
*/
r = get_proc_field("/proc/self/status", "TracerPid", &p);
if (r < 0)
log_debug_errno(r, "Failed to read our own trace PID, ignoring: %m");
else if (!streq(p, "0")) {
pid_t ptrace_pid;
r = parse_pid(p, &ptrace_pid);
if (r < 0)
log_debug_errno(r, "Failed to parse our own tracer PID, ignoring: %m");
else {
_cleanup_free_ char *ptrace_comm = NULL;
const char *pf;
pf = procfs_file_alloca(ptrace_pid, "comm");
r = read_one_line_file(pf, &ptrace_comm);
if (r < 0)
log_debug_errno(r, "Failed to read %s, ignoring: %m", pf);
else if (startswith(ptrace_comm, "proot")) {
v = VIRTUALIZATION_PROOT;
goto finish;
}
}
}
/* The container manager might have placed this in the /run/host/ hierarchy for us, which is best
* because we can be consumed just like that, without special privileges. */
r = read_one_line_file("/run/host/container-manager", &m);
if (r > 0) {
e = m;
goto translate_name;
}
if (!IN_SET(r, -ENOENT, 0))
return log_debug_errno(r, "Failed to read /run/host/container-manager: %m");
if (getpid_cached() == 1) {
/* If we are PID 1 we can just check our own environment variable, and that's authoritative.
* We distinguish three cases:
* - the variable is not defined → we jump to other checks
* - the variable is defined to an empty value → we are not in a container
* - anything else → some container, either one of the known ones or "container-other"
*/
e = getenv("container");
if (!e)
goto check_files;
if (isempty(e)) {
v = VIRTUALIZATION_NONE;
goto finish;
}
goto translate_name;
}
/* Otherwise, PID 1 might have dropped this information into a file in /run. This is better than accessing
* /proc/1/environ, since we don't need CAP_SYS_PTRACE for that. */
r = read_one_line_file("/run/systemd/container", &m);
if (r > 0) {
e = m;
goto translate_name;
}
if (!IN_SET(r, -ENOENT, 0))
return log_debug_errno(r, "Failed to read /run/systemd/container: %m");
/* Fallback for cases where PID 1 was not systemd (for example, cases where init=/bin/sh is used. */
r = getenv_for_pid(1, "container", &m);
if (r > 0) {
e = m;
goto translate_name;
}
if (r < 0) /* This only works if we have CAP_SYS_PTRACE, hence let's better ignore failures here */
log_debug_errno(r, "Failed to read $container of PID 1, ignoring: %m");
check_files:
/* Check for existence of some well-known files. We only do this after checking
* for other specific container managers, otherwise we risk mistaking another
* container manager for Docker: the /.dockerenv file could inadvertently end up
* in a file system image. */
v = detect_container_files();
if (v < 0)
return v;
if (v != VIRTUALIZATION_NONE)
goto finish;
/* Finally, the root pid namespace has an hardcoded inode number of 0xEFFFFFFC since kernel 3.8, so
* if all else fails we can check the inode number of our pid namespace and compare it. */
if (running_in_pidns() > 0) {
log_debug("Running in a pid namespace, assuming unknown container manager.");
v = VIRTUALIZATION_CONTAINER_OTHER;
goto finish;
}
/* If none of that worked, give up, assume no container manager. */
v = VIRTUALIZATION_NONE;
goto finish;
translate_name:
if (streq(e, "oci")) {
/* Some images hardcode container=oci, but OCI is not a specific container manager.
* Try to detect one based on well-known files. */
v = detect_container_files();
if (v == VIRTUALIZATION_NONE)
v = VIRTUALIZATION_CONTAINER_OTHER;
goto finish;
}
v = container_from_string(e);
if (v < 0)
v = VIRTUALIZATION_CONTAINER_OTHER;
finish:
log_debug("Found container virtualization %s.", virtualization_to_string(v));
cached_found = v;
return v;
}
Virtualization detect_virtualization(void) {
int v;
v = detect_container();
if (v != VIRTUALIZATION_NONE)
return v;
return detect_vm();
}
int running_in_userns(void) {
int r;
r = namespace_is_init(NAMESPACE_USER);
if (r < 0)
return log_debug_errno(r, "Failed to test if in root user namespace, ignoring: %m");
return !r;
}
int running_in_chroot(void) {
int r;
/* If we're PID1, /proc may not be mounted (and most likely we're not in a chroot). But PID1 will
* mount /proc, so all other programs can assume that if /proc is *not* available, we're in some
* chroot. */
r = getenv_bool("SYSTEMD_IN_CHROOT");
if (r >= 0)
return r > 0;
if (r != -ENXIO)
log_debug_errno(r, "Failed to parse $SYSTEMD_IN_CHROOT, ignoring: %m");
/* Deprecated but kept for backwards compatibility. */
if (getenv_bool("SYSTEMD_IGNORE_CHROOT") > 0)
return 0;
r = inode_same("/proc/1/root", "/", /* flags = */ 0);
if (r == -ENOENT) {
r = proc_mounted();
if (r == 0) {
if (getpid_cached() == 1)
return false; /* We will mount /proc, assuming we're not in a chroot. */
log_debug("/proc/ is not mounted, assuming we're in a chroot.");
return true;
}
if (r > 0) /* If we have fake /proc/, we can't do the check properly. */
return -ENOSYS;
}
if (r < 0)
return r;
return r == 0;
}
#if defined(__i386__) || defined(__x86_64__)
struct cpuid_table_entry {
uint32_t flag_bit;
const char *name;
};
static const struct cpuid_table_entry leaf1_edx[] = {
{ 0, "fpu" },
{ 1, "vme" },
{ 2, "de" },
{ 3, "pse" },
{ 4, "tsc" },
{ 5, "msr" },
{ 6, "pae" },
{ 7, "mce" },
{ 8, "cx8" },
{ 9, "apic" },
{ 11, "sep" },
{ 12, "mtrr" },
{ 13, "pge" },
{ 14, "mca" },
{ 15, "cmov" },
{ 16, "pat" },
{ 17, "pse36" },
{ 19, "clflush" },
{ 23, "mmx" },
{ 24, "fxsr" },
{ 25, "sse" },
{ 26, "sse2" },
{ 28, "ht" },
};
static const struct cpuid_table_entry leaf1_ecx[] = {
{ 0, "pni" },
{ 1, "pclmul" },
{ 3, "monitor" },
{ 9, "ssse3" },
{ 12, "fma3" },
{ 13, "cx16" },
{ 19, "sse4_1" },
{ 20, "sse4_2" },
{ 22, "movbe" },
{ 23, "popcnt" },
{ 25, "aes" },
{ 26, "xsave" },
{ 27, "osxsave" },
{ 28, "avx" },
{ 29, "f16c" },
{ 30, "rdrand" },
};
static const struct cpuid_table_entry leaf7_ebx[] = {
{ 3, "bmi1" },
{ 5, "avx2" },
{ 8, "bmi2" },
{ 18, "rdseed" },
{ 19, "adx" },
{ 29, "sha_ni" },
};
static const struct cpuid_table_entry leaf81_edx[] = {
{ 11, "syscall" },
{ 27, "rdtscp" },
{ 29, "lm" },
};
static const struct cpuid_table_entry leaf81_ecx[] = {
{ 0, "lahf_lm" },
{ 5, "abm" },
};
static const struct cpuid_table_entry leaf87_edx[] = {
{ 8, "constant_tsc" },
};
static bool given_flag_in_set(const char *flag, const struct cpuid_table_entry *set, size_t set_size, uint32_t val) {
for (size_t i = 0; i < set_size; i++) {
if ((UINT32_C(1) << set[i].flag_bit) & val &&
streq(flag, set[i].name))
return true;
}
return false;
}
static bool real_has_cpu_with_flag(const char *flag) {
uint32_t eax, ebx, ecx, edx;
if (__get_cpuid(1, &eax, &ebx, &ecx, &edx)) {
if (given_flag_in_set(flag, leaf1_ecx, ELEMENTSOF(leaf1_ecx), ecx))
return true;
if (given_flag_in_set(flag, leaf1_edx, ELEMENTSOF(leaf1_edx), edx))
return true;
}
if (__get_cpuid_count(7, 0, &eax, &ebx, &ecx, &edx)) {
if (given_flag_in_set(flag, leaf7_ebx, ELEMENTSOF(leaf7_ebx), ebx))
return true;
}
if (__get_cpuid(0x80000001U, &eax, &ebx, &ecx, &edx)) {
if (given_flag_in_set(flag, leaf81_ecx, ELEMENTSOF(leaf81_ecx), ecx))
return true;
if (given_flag_in_set(flag, leaf81_edx, ELEMENTSOF(leaf81_edx), edx))
return true;
}
if (__get_cpuid(0x80000007U, &eax, &ebx, &ecx, &edx))
if (given_flag_in_set(flag, leaf87_edx, ELEMENTSOF(leaf87_edx), edx))
return true;
return false;
}
#endif
bool has_cpu_with_flag(const char *flag) {
/* CPUID is an x86 specific interface. Assume on all others that no CPUs have those flags. */
#if defined(__i386__) || defined(__x86_64__)
return real_has_cpu_with_flag(flag);
#else
return false;
#endif
}
static const char *const virtualization_table[_VIRTUALIZATION_MAX] = {
[VIRTUALIZATION_NONE] = "none",
[VIRTUALIZATION_KVM] = "kvm",
[VIRTUALIZATION_AMAZON] = "amazon",
[VIRTUALIZATION_QEMU] = "qemu",
[VIRTUALIZATION_BOCHS] = "bochs",
[VIRTUALIZATION_XEN] = "xen",
[VIRTUALIZATION_UML] = "uml",
[VIRTUALIZATION_VMWARE] = "vmware",
[VIRTUALIZATION_ORACLE] = "oracle",
[VIRTUALIZATION_MICROSOFT] = "microsoft",
[VIRTUALIZATION_ZVM] = "zvm",
[VIRTUALIZATION_PARALLELS] = "parallels",
[VIRTUALIZATION_BHYVE] = "bhyve",
[VIRTUALIZATION_QNX] = "qnx",
[VIRTUALIZATION_ACRN] = "acrn",
[VIRTUALIZATION_POWERVM] = "powervm",
[VIRTUALIZATION_APPLE] = "apple",
[VIRTUALIZATION_SRE] = "sre",
[VIRTUALIZATION_GOOGLE] = "google",
[VIRTUALIZATION_VM_OTHER] = "vm-other",
[VIRTUALIZATION_SYSTEMD_NSPAWN] = "systemd-nspawn",
[VIRTUALIZATION_LXC_LIBVIRT] = "lxc-libvirt",
[VIRTUALIZATION_LXC] = "lxc",
[VIRTUALIZATION_OPENVZ] = "openvz",
[VIRTUALIZATION_DOCKER] = "docker",
[VIRTUALIZATION_PODMAN] = "podman",
[VIRTUALIZATION_RKT] = "rkt",
[VIRTUALIZATION_WSL] = "wsl",
[VIRTUALIZATION_PROOT] = "proot",
[VIRTUALIZATION_POUCH] = "pouch",
[VIRTUALIZATION_CONTAINER_OTHER] = "container-other",
};
DEFINE_STRING_TABLE_LOOKUP(virtualization, Virtualization);
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