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virt: drop /proc/1/sched hack

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On really old kernels (< 4.14+) a bug in /proc/1/sched handling in the
kernel could be used to determine whether we are running in a PID
namespace. This hasn't worked for a long time, and there's little point
in making things work on old kernels we can't make work on current
kernels, hence let's drop that old cruft.

See: #8153
This commit is contained in:
Lennart Poettering 2020-12-09 16:16:21 +01:00
parent 1c36b8bf53
commit 5e3effb1f3
1 changed files with 2 additions and 19 deletions
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21
src/basic/virt.c
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@ -517,7 +517,7 @@ int detect_container(void) {
*/
e = getenv("container");
if (!e)
goto check_sched;
goto none;
if (isempty(e)) {
r = VIRTUALIZATION_NONE;
goto finish;
@ -545,24 +545,7 @@ int detect_container(void) {
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");
/* Interestingly /proc/1/sched actually shows the host's PID for what we see as PID 1. If the PID
* shown there is not 1, we know we are in a PID namespace and hence a container. */
check_sched:
r = read_one_line_file("/proc/1/sched", &m);
if (r >= 0) {
const char *t;
t = strrchr(m, '(');
if (!t)
return -EIO;
if (!startswith(t, "(1,")) {
r = VIRTUALIZATION_CONTAINER_OTHER;
goto finish;
}
} else if (r != -ENOENT)
return r;
none:
/* If that didn't work, give up, assume no container manager. */
r = VIRTUALIZATION_NONE;
goto finish;