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![Arnaldo Carvalho de Melo](/assets/img/avatar_default.png)
To reduce the use of RC_CHK_ACCESS(nsi). Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
376 lines
7.5 KiB
C
376 lines
7.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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*
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* Copyright (C) 2017 Hari Bathini, IBM Corporation
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*/
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#include "namespaces.h"
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#include "event.h"
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#include "get_current_dir_name.h"
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <sched.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <asm/bug.h>
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#include <linux/kernel.h>
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#include <linux/zalloc.h>
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static const char *perf_ns__names[] = {
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[NET_NS_INDEX] = "net",
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[UTS_NS_INDEX] = "uts",
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[IPC_NS_INDEX] = "ipc",
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[PID_NS_INDEX] = "pid",
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[USER_NS_INDEX] = "user",
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[MNT_NS_INDEX] = "mnt",
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[CGROUP_NS_INDEX] = "cgroup",
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};
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const char *perf_ns__name(unsigned int id)
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{
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if (id >= ARRAY_SIZE(perf_ns__names))
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return "UNKNOWN";
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return perf_ns__names[id];
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}
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struct namespaces *namespaces__new(struct perf_record_namespaces *event)
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{
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struct namespaces *namespaces;
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u64 link_info_size = ((event ? event->nr_namespaces : NR_NAMESPACES) *
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sizeof(struct perf_ns_link_info));
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namespaces = zalloc(sizeof(struct namespaces) + link_info_size);
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if (!namespaces)
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return NULL;
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namespaces->end_time = -1;
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if (event)
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memcpy(namespaces->link_info, event->link_info, link_info_size);
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return namespaces;
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}
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void namespaces__free(struct namespaces *namespaces)
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{
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free(namespaces);
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}
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static int nsinfo__get_nspid(pid_t *tgid, pid_t *nstgid, bool *in_pidns, const char *path)
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{
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FILE *f = NULL;
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char *statln = NULL;
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size_t linesz = 0;
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char *nspid;
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f = fopen(path, "r");
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if (f == NULL)
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return -1;
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while (getline(&statln, &linesz, f) != -1) {
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/* Use tgid if CONFIG_PID_NS is not defined. */
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if (strstr(statln, "Tgid:") != NULL) {
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*tgid = (pid_t)strtol(strrchr(statln, '\t'), NULL, 10);
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*nstgid = *tgid;
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}
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if (strstr(statln, "NStgid:") != NULL) {
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nspid = strrchr(statln, '\t');
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*nstgid = (pid_t)strtol(nspid, NULL, 10);
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/*
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* If innermost tgid is not the first, process is in a different
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* PID namespace.
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*/
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*in_pidns = (statln + sizeof("NStgid:") - 1) != nspid;
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break;
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}
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}
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fclose(f);
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free(statln);
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return 0;
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}
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int nsinfo__init(struct nsinfo *nsi)
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{
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char oldns[PATH_MAX];
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char spath[PATH_MAX];
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char *newns = NULL;
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struct stat old_stat;
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struct stat new_stat;
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int rv = -1;
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if (snprintf(oldns, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX)
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return rv;
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if (asprintf(&newns, "/proc/%d/ns/mnt", nsinfo__pid(nsi)) == -1)
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return rv;
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if (stat(oldns, &old_stat) < 0)
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goto out;
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if (stat(newns, &new_stat) < 0)
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goto out;
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/* Check if the mount namespaces differ, if so then indicate that we
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* want to switch as part of looking up dso/map data.
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*/
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if (old_stat.st_ino != new_stat.st_ino) {
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RC_CHK_ACCESS(nsi)->need_setns = true;
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RC_CHK_ACCESS(nsi)->mntns_path = newns;
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newns = NULL;
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}
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/* If we're dealing with a process that is in a different PID namespace,
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* attempt to work out the innermost tgid for the process.
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*/
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if (snprintf(spath, PATH_MAX, "/proc/%d/status", nsinfo__pid(nsi)) >= PATH_MAX)
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goto out;
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rv = nsinfo__get_nspid(&RC_CHK_ACCESS(nsi)->tgid, &RC_CHK_ACCESS(nsi)->nstgid,
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&RC_CHK_ACCESS(nsi)->in_pidns, spath);
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out:
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free(newns);
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return rv;
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}
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static struct nsinfo *nsinfo__alloc(void)
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{
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struct nsinfo *res;
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RC_STRUCT(nsinfo) *nsi;
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nsi = calloc(1, sizeof(*nsi));
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if (ADD_RC_CHK(res, nsi))
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refcount_set(&nsi->refcnt, 1);
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return res;
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}
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struct nsinfo *nsinfo__new(pid_t pid)
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{
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struct nsinfo *nsi;
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if (pid == 0)
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return NULL;
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nsi = nsinfo__alloc();
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if (!nsi)
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return NULL;
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RC_CHK_ACCESS(nsi)->pid = pid;
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RC_CHK_ACCESS(nsi)->tgid = pid;
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RC_CHK_ACCESS(nsi)->nstgid = pid;
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nsinfo__clear_need_setns(nsi);
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RC_CHK_ACCESS(nsi)->in_pidns = false;
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/* Init may fail if the process exits while we're trying to look at its
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* proc information. In that case, save the pid but don't try to enter
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* the namespace.
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*/
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if (nsinfo__init(nsi) == -1)
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nsinfo__clear_need_setns(nsi);
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return nsi;
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}
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static const char *nsinfo__mntns_path(const struct nsinfo *nsi)
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{
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return RC_CHK_ACCESS(nsi)->mntns_path;
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}
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struct nsinfo *nsinfo__copy(const struct nsinfo *nsi)
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{
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struct nsinfo *nnsi;
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if (nsi == NULL)
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return NULL;
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nnsi = nsinfo__alloc();
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if (!nnsi)
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return NULL;
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RC_CHK_ACCESS(nnsi)->pid = nsinfo__pid(nsi);
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RC_CHK_ACCESS(nnsi)->tgid = nsinfo__tgid(nsi);
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RC_CHK_ACCESS(nnsi)->nstgid = nsinfo__nstgid(nsi);
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RC_CHK_ACCESS(nnsi)->need_setns = nsinfo__need_setns(nsi);
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RC_CHK_ACCESS(nnsi)->in_pidns = nsinfo__in_pidns(nsi);
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if (nsinfo__mntns_path(nsi)) {
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RC_CHK_ACCESS(nnsi)->mntns_path = strdup(nsinfo__mntns_path(nsi));
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if (!RC_CHK_ACCESS(nnsi)->mntns_path) {
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nsinfo__put(nnsi);
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return NULL;
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}
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}
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return nnsi;
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}
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static refcount_t *nsinfo__refcnt(struct nsinfo *nsi)
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{
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return &RC_CHK_ACCESS(nsi)->refcnt;
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}
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static void nsinfo__delete(struct nsinfo *nsi)
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{
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if (nsi) {
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WARN_ONCE(refcount_read(nsinfo__refcnt(nsi)) != 0, "nsinfo refcnt unbalanced\n");
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zfree(&RC_CHK_ACCESS(nsi)->mntns_path);
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RC_CHK_FREE(nsi);
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}
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}
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struct nsinfo *nsinfo__get(struct nsinfo *nsi)
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{
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struct nsinfo *result;
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if (RC_CHK_GET(result, nsi))
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refcount_inc(nsinfo__refcnt(nsi));
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return result;
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}
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void nsinfo__put(struct nsinfo *nsi)
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{
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if (nsi && refcount_dec_and_test(nsinfo__refcnt(nsi)))
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nsinfo__delete(nsi);
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else
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RC_CHK_PUT(nsi);
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}
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bool nsinfo__need_setns(const struct nsinfo *nsi)
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{
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return RC_CHK_ACCESS(nsi)->need_setns;
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}
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void nsinfo__clear_need_setns(struct nsinfo *nsi)
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{
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RC_CHK_ACCESS(nsi)->need_setns = false;
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}
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pid_t nsinfo__tgid(const struct nsinfo *nsi)
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{
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return RC_CHK_ACCESS(nsi)->tgid;
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}
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pid_t nsinfo__nstgid(const struct nsinfo *nsi)
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{
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return RC_CHK_ACCESS(nsi)->nstgid;
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}
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pid_t nsinfo__pid(const struct nsinfo *nsi)
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{
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return RC_CHK_ACCESS(nsi)->pid;
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}
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pid_t nsinfo__in_pidns(const struct nsinfo *nsi)
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{
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return RC_CHK_ACCESS(nsi)->in_pidns;
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}
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void nsinfo__mountns_enter(struct nsinfo *nsi,
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struct nscookie *nc)
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{
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char curpath[PATH_MAX];
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int oldns = -1;
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int newns = -1;
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char *oldcwd = NULL;
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if (nc == NULL)
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return;
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nc->oldns = -1;
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nc->newns = -1;
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if (!nsi || !nsinfo__need_setns(nsi))
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return;
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if (snprintf(curpath, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX)
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return;
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oldcwd = get_current_dir_name();
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if (!oldcwd)
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return;
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oldns = open(curpath, O_RDONLY);
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if (oldns < 0)
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goto errout;
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newns = open(nsinfo__mntns_path(nsi), O_RDONLY);
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if (newns < 0)
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goto errout;
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if (setns(newns, CLONE_NEWNS) < 0)
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goto errout;
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nc->oldcwd = oldcwd;
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nc->oldns = oldns;
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nc->newns = newns;
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return;
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errout:
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free(oldcwd);
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if (oldns > -1)
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close(oldns);
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if (newns > -1)
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close(newns);
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}
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void nsinfo__mountns_exit(struct nscookie *nc)
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{
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if (nc == NULL || nc->oldns == -1 || nc->newns == -1 || !nc->oldcwd)
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return;
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setns(nc->oldns, CLONE_NEWNS);
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if (nc->oldcwd) {
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WARN_ON_ONCE(chdir(nc->oldcwd));
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zfree(&nc->oldcwd);
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}
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if (nc->oldns > -1) {
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close(nc->oldns);
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nc->oldns = -1;
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}
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if (nc->newns > -1) {
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close(nc->newns);
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nc->newns = -1;
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}
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}
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char *nsinfo__realpath(const char *path, struct nsinfo *nsi)
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{
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char *rpath;
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struct nscookie nsc;
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nsinfo__mountns_enter(nsi, &nsc);
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rpath = realpath(path, NULL);
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nsinfo__mountns_exit(&nsc);
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return rpath;
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}
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int nsinfo__stat(const char *filename, struct stat *st, struct nsinfo *nsi)
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{
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int ret;
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struct nscookie nsc;
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nsinfo__mountns_enter(nsi, &nsc);
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ret = stat(filename, st);
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nsinfo__mountns_exit(&nsc);
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return ret;
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}
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bool nsinfo__is_in_root_namespace(void)
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{
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pid_t tgid = 0, nstgid = 0;
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bool in_pidns = false;
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nsinfo__get_nspid(&tgid, &nstgid, &in_pidns, "/proc/self/status");
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return !in_pidns;
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}
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