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conf: write "deny" to /proc/[pid]/setgroups #2067

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merged 4 commits into from
Jan 4, 2018
Merged

conf: write "deny" to /proc/[pid]/setgroups #2067

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a19b974
conf: write "deny" to /proc/[pid]/setgroups
Jan 3, 2018
c7e345a
conf: non-functional changes
Jan 4, 2018
dcf0ffd
conf: rework userns_exec_1()
Jan 4, 2018
bd8ef4e
cgfsng: only establish mapping once
Jan 4, 2018
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86 changes: 48 additions & 38 deletions src/lxc/cgroups/cgfsng.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1206,7 +1206,7 @@ static void *cgfsng_init(struct lxc_handler *handler)
return NULL;
}

static int cgroup_rmdir(char *dirname)
static int recursive_destroy(char *dirname)
{
int ret;
struct dirent *direntp;
Expand Down Expand Up @@ -1241,40 +1241,65 @@ static int cgroup_rmdir(char *dirname)
if (!S_ISDIR(mystat.st_mode))
goto next;

ret = cgroup_rmdir(pathname);
ret = recursive_destroy(pathname);
if (ret < 0)
r = -1;
next:
next:
free(pathname);
}

ret = rmdir(dirname);
if (ret < 0) {
if (!r)
WARN("Failed to delete \"%s\": %s", dirname,
strerror(errno));
WARN("%s - Failed to delete \"%s\"", strerror(errno),
dirname);
r = -1;
}

ret = closedir(dir);
if (ret < 0) {
if (!r)
WARN("Failed to delete \"%s\": %s", dirname,
strerror(errno));
WARN("%s - Failed to delete \"%s\"", strerror(errno),
dirname);
r = -1;
}

return r;
}

static int cgroup_rmdir(char *container_cgroup)
{
int i;

if (!container_cgroup || !hierarchies)
return 0;

for (i = 0; hierarchies[i]; i++) {
int ret;
struct hierarchy *h = hierarchies[i];

if (!h->fullcgpath)
continue;

ret = recursive_destroy(h->fullcgpath);
if (ret < 0)
WARN("Failed to destroy \"%s\"", h->fullcgpath);

free(h->fullcgpath);
h->fullcgpath = NULL;
}

return 0;
}

struct generic_userns_exec_data {
struct cgfsng_handler_data *d;
struct lxc_conf *conf;
uid_t origuid; /* target uid in parent namespace */
char *path;
};

static int rmdir_wrapper(void *data)
static int cgroup_rmdir_wrapper(void *data)
{
struct generic_userns_exec_data *arg = data;
uid_t nsuid = (arg->conf->root_nsuid_map != NULL) ? 0 : arg->conf->init_uid;
Expand All @@ -1284,48 +1309,33 @@ static int rmdir_wrapper(void *data)
SYSERROR("Failed to setgid to 0");
if (setresuid(nsuid, nsuid, nsuid) < 0)
SYSERROR("Failed to setuid to 0");
if (setgroups(0, NULL) < 0)
if (setgroups(0, NULL) < 0 && errno != EPERM)
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So we'll ignore failures to write due to eperm. Is that ok?

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It should only ever mean that there's a "deny" in /proc/[pid]/setgroups but I don't want to open this and read it every time. But we could.

SYSERROR("Failed to clear groups");

return cgroup_rmdir(arg->path);
return cgroup_rmdir(arg->d->container_cgroup);
}

void recursive_destroy(char *path, struct lxc_conf *conf)
static void cgfsng_destroy(void *hdata, struct lxc_conf *conf)
{
int r;
int ret;
struct cgfsng_handler_data *d = hdata;
struct generic_userns_exec_data wrap;

if (!d)
return;

wrap.origuid = 0;
wrap.d = NULL;
wrap.path = path;
wrap.d = hdata;
wrap.conf = conf;

if (conf && !lxc_list_empty(&conf->id_map))
r = userns_exec_1(conf, rmdir_wrapper, &wrap, "rmdir_wrapper");
ret = userns_exec_1(conf, cgroup_rmdir_wrapper, &wrap,
"cgroup_rmdir_wrapper");
else
r = cgroup_rmdir(path);

if (r < 0)
ERROR("Error destroying %s", path);
}

static void cgfsng_destroy(void *hdata, struct lxc_conf *conf)
{
struct cgfsng_handler_data *d = hdata;

if (!d)
ret = cgroup_rmdir(d->container_cgroup);
if (ret < 0) {
WARN("Failed to destroy cgroups");
return;

if (d->container_cgroup && hierarchies) {
int i;
for (i = 0; hierarchies[i]; i++) {
struct hierarchy *h = hierarchies[i];
if (h->fullcgpath) {
recursive_destroy(h->fullcgpath, conf);
free(h->fullcgpath);
h->fullcgpath = NULL;
}
}
}

free_handler_data(d);
Expand Down Expand Up @@ -1481,7 +1491,7 @@ static int chown_cgroup_wrapper(void *data)
SYSERROR("Failed to setgid to 0");
if (setresuid(nsuid, nsuid, nsuid) < 0)
SYSERROR("Failed to setuid to 0");
if (setgroups(0, NULL) < 0)
if (setgroups(0, NULL) < 0 && errno != EPERM)
SYSERROR("Failed to clear groups");

destuid = get_ns_uid(arg->origuid);
Expand Down
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