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perf namespaces: Add reference count checking
Add reference count checking controlled by REFCNT_CHECKING ifdef. The reference count checking interposes an allocated pointer between the reference counted struct on a get and frees the pointer on a put. Accesses after a put cause faults and use after free, missed puts are caughts as leaks and double puts are double frees. This checking helped resolve a memory leak and use after free: https://lore.kernel.org/linux-perf-users/CAP-5=fWZH20L4kv-BwVtGLwR=Em3AOOT+Q4QGivvQuYn5AsPRg@mail.gmail.com/ Signed-off-by: Ian Rogers <irogers@google.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com> Cc: Dmitriy Vyukov <dvyukov@google.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Riccardo Mancini <rickyman7@gmail.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Brennan <stephen.s.brennan@oracle.com> Link: https://lore.kernel.org/lkml/20230407230405.2931830-4-irogers@google.com [ Extracted from a larger patch ] Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Ian Rogers
Arnaldo Carvalho de Melo
parent
7031edac9d
commit
c35ce1d918
@ -60,7 +60,7 @@ void namespaces__free(struct namespaces *namespaces)
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free(namespaces);
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}
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static int nsinfo__get_nspid(struct nsinfo *nsi, const char *path)
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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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@ -74,19 +74,18 @@ static int nsinfo__get_nspid(struct nsinfo *nsi, const char *path)
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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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nsi->tgid = (pid_t)strtol(strrchr(statln, '\t'),
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NULL, 10);
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nsi->nstgid = nsinfo__tgid(nsi);
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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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nsi->nstgid = (pid_t)strtol(nspid, NULL, 10);
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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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nsi->in_pidns = (statln + sizeof("NStgid:") - 1) != nspid;
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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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@ -121,8 +120,8 @@ int nsinfo__init(struct nsinfo *nsi)
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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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nsi->need_setns = true;
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nsi->mntns_path = newns;
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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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@ -132,13 +131,26 @@ int nsinfo__init(struct nsinfo *nsi)
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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(nsi, spath);
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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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@ -146,22 +158,21 @@ struct nsinfo *nsinfo__new(pid_t pid)
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if (pid == 0)
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return NULL;
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nsi = calloc(1, sizeof(*nsi));
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if (nsi != NULL) {
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nsi->pid = pid;
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nsi->tgid = pid;
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nsi->nstgid = pid;
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nsi->need_setns = false;
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nsi->in_pidns = false;
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/* Init may fail if the process exits while we're trying to look
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* at its proc information. In that case, save the pid but
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* don't try to enter the namespace.
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*/
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if (nsinfo__init(nsi) == -1)
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nsi->need_setns = false;
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nsi = nsinfo__alloc();
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if (!nsi)
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return NULL;
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refcount_set(&nsi->refcnt, 1);
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}
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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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RC_CHK_ACCESS(nsi)->need_setns = false;
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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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RC_CHK_ACCESS(nsi)->need_setns = false;
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return nsi;
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}
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@ -173,21 +184,21 @@ struct nsinfo *nsinfo__copy(const struct nsinfo *nsi)
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if (nsi == NULL)
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return NULL;
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nnsi = calloc(1, sizeof(*nnsi));
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if (nnsi != NULL) {
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nnsi->pid = nsinfo__pid(nsi);
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nnsi->tgid = nsinfo__tgid(nsi);
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nnsi->nstgid = nsinfo__nstgid(nsi);
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nnsi->need_setns = nsinfo__need_setns(nsi);
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nnsi->in_pidns = nsinfo__in_pidns(nsi);
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if (nsi->mntns_path) {
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nnsi->mntns_path = strdup(nsi->mntns_path);
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if (!nnsi->mntns_path) {
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free(nnsi);
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return NULL;
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}
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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 (RC_CHK_ACCESS(nsi)->mntns_path) {
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RC_CHK_ACCESS(nnsi)->mntns_path = strdup(RC_CHK_ACCESS(nsi)->mntns_path);
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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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refcount_set(&nnsi->refcnt, 1);
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}
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return nnsi;
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@ -195,51 +206,60 @@ struct nsinfo *nsinfo__copy(const struct nsinfo *nsi)
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static void nsinfo__delete(struct nsinfo *nsi)
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{
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zfree(&nsi->mntns_path);
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free(nsi);
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if (nsi) {
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WARN_ONCE(refcount_read(&RC_CHK_ACCESS(nsi)->refcnt) != 0,
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"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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if (nsi)
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refcount_inc(&nsi->refcnt);
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return nsi;
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struct nsinfo *result;
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if (RC_CHK_GET(result, nsi))
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refcount_inc(&RC_CHK_ACCESS(nsi)->refcnt);
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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(&nsi->refcnt))
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if (nsi && refcount_dec_and_test(&RC_CHK_ACCESS(nsi)->refcnt))
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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 nsi->need_setns;
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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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nsi->need_setns = false;
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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 nsi->tgid;
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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 nsi->nstgid;
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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 nsi->pid;
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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 nsi->in_pidns;
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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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@ -256,7 +276,7 @@ void nsinfo__mountns_enter(struct nsinfo *nsi,
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nc->oldns = -1;
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nc->newns = -1;
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if (!nsi || !nsi->need_setns)
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if (!nsi || !RC_CHK_ACCESS(nsi)->need_setns)
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return;
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if (snprintf(curpath, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX)
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@ -270,7 +290,7 @@ void nsinfo__mountns_enter(struct nsinfo *nsi,
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if (oldns < 0)
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goto errout;
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newns = open(nsi->mntns_path, O_RDONLY);
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newns = open(RC_CHK_ACCESS(nsi)->mntns_path, O_RDONLY);
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if (newns < 0)
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goto errout;
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@ -339,9 +359,9 @@ int nsinfo__stat(const char *filename, struct stat *st, struct nsinfo *nsi)
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bool nsinfo__is_in_root_namespace(void)
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{
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struct nsinfo nsi;
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pid_t tgid = 0, nstgid = 0;
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bool in_pidns = false;
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memset(&nsi, 0x0, sizeof(nsi));
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nsinfo__get_nspid(&nsi, "/proc/self/status");
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return !nsi.in_pidns;
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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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@ -13,6 +13,7 @@
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#include <linux/perf_event.h>
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#include <linux/refcount.h>
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#include <linux/types.h>
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#include <internal/rc_check.h>
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#ifndef HAVE_SETNS_SUPPORT
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int setns(int fd, int nstype);
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@ -29,7 +30,7 @@ struct namespaces {
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struct namespaces *namespaces__new(struct perf_record_namespaces *event);
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void namespaces__free(struct namespaces *namespaces);
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struct nsinfo {
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DECLARE_RC_STRUCT(nsinfo) {
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pid_t pid;
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pid_t tgid;
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pid_t nstgid;
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