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core: rework cgroup path parse logic

Various cleanups, be stricter when parsing unit paths.

Most importantly: return the root slice "-.slice" when asked for slice
of paths that contain no slice component.
This commit is contained in:
Lennart Poettering 2015-04-30 00:47:41 +02:00
parent 5cc0748e19
commit 8b0849e971
4 changed files with 172 additions and 69 deletions

View File

@ -40,6 +40,7 @@
#include "fileio.h"
#include "special.h"
#include "mkdir.h"
#include "login-shared.h"
int cg_enumerate_processes(const char *controller, const char *path, FILE **_f) {
_cleanup_free_ char *fs = NULL;
@ -1140,13 +1141,17 @@ int cg_pid_get_path_shifted(pid_t pid, const char *root, char **cgroup) {
}
int cg_path_decode_unit(const char *cgroup, char **unit){
char *e, *c, *s;
char *c, *s;
size_t n;
assert(cgroup);
assert(unit);
e = strchrnul(cgroup, '/');
c = strndupa(cgroup, e - cgroup);
n = strcspn(cgroup, "/");
if (n < 3)
return -ENXIO;
c = strndupa(cgroup, n);
c = cg_unescape(c);
if (!unit_name_is_valid(c, TEMPLATE_INVALID))
@ -1160,7 +1165,31 @@ int cg_path_decode_unit(const char *cgroup, char **unit){
return 0;
}
static bool valid_slice_name(const char *p, size_t n) {
if (!p)
return false;
if (n < strlen("x.slice"))
return false;
if (memcmp(p + n - 6, ".slice", 6) == 0) {
char buf[n+1], *c;
memcpy(buf, p, n);
buf[n] = 0;
c = cg_unescape(buf);
return unit_name_is_valid(c, TEMPLATE_INVALID);
}
return false;
}
static const char *skip_slices(const char *p) {
assert(p);
/* Skips over all slice assignments */
for (;;) {
@ -1169,22 +1198,35 @@ static const char *skip_slices(const char *p) {
p += strspn(p, "/");
n = strcspn(p, "/");
if (n <= 6 || memcmp(p + n - 6, ".slice", 6) != 0)
if (!valid_slice_name(p, n))
return p;
p += n;
}
}
int cg_path_get_unit(const char *path, char **unit) {
int cg_path_get_unit(const char *path, char **ret) {
const char *e;
char *unit;
int r;
assert(path);
assert(unit);
assert(ret);
e = skip_slices(path);
return cg_path_decode_unit(e, unit);
r = cg_path_decode_unit(e, &unit);
if (r < 0)
return r;
/* We skipped over the slices, don't accept any now */
if (endswith(unit, ".slice")) {
free(unit);
return -ENXIO;
}
*ret = unit;
return 0;
}
int cg_pid_get_unit(pid_t pid, char **unit) {
@ -1206,18 +1248,35 @@ int cg_pid_get_unit(pid_t pid, char **unit) {
static const char *skip_session(const char *p) {
size_t n;
assert(p);
if (isempty(p))
return NULL;
p += strspn(p, "/");
n = strcspn(p, "/");
if (n < strlen("session-x.scope") || memcmp(p, "session-", 8) != 0 || memcmp(p + n - 6, ".scope", 6) != 0)
if (n < strlen("session-x.scope"))
return NULL;
p += n;
p += strspn(p, "/");
if (memcmp(p, "session-", 8) == 0 && memcmp(p + n - 6, ".scope", 6) == 0) {
char buf[n - 8 - 6 + 1];
return p;
memcpy(buf, p + 8, n - 8 - 6);
buf[n - 8 - 6] = 0;
/* Note that session scopes never need unescaping,
* since they cannot conflict with the kernel's own
* names, hence we don't need to call cg_unescape()
* here. */
if (!session_id_valid(buf))
return false;
p += n;
p += strspn(p, "/");
return p;
}
return NULL;
}
/**
@ -1226,25 +1285,45 @@ static const char *skip_session(const char *p) {
static const char *skip_user_manager(const char *p) {
size_t n;
assert(p);
if (isempty(p))
return NULL;
p += strspn(p, "/");
n = strcspn(p, "/");
if (n < strlen("user@x.service") || memcmp(p, "user@", 5) != 0 || memcmp(p + n - 8, ".service", 8) != 0)
if (n < strlen("user@x.service"))
return NULL;
p += n;
p += strspn(p, "/");
if (memcmp(p, "user@", 5) == 0 && memcmp(p + n - 8, ".service", 8) == 0) {
char buf[n - 5 - 8 + 1];
return p;
memcpy(buf, p + 5, n - 5 - 8);
buf[n - 5 - 8] = 0;
/* Note that user manager services never need unescaping,
* since they cannot conflict with the kernel's own
* names, hence we don't need to call cg_unescape()
* here. */
if (parse_uid(buf, NULL) < 0)
return NULL;
p += n;
p += strspn(p, "/");
return p;
}
return NULL;
}
int cg_path_get_user_unit(const char *path, char **unit) {
int cg_path_get_user_unit(const char *path, char **ret) {
const char *e, *t;
char *unit;
int r;
assert(path);
assert(unit);
assert(ret);
/* We always have to parse the path from the beginning as unit
* cgroups might have arbitrary child cgroups and we shouldn't get
@ -1253,17 +1332,30 @@ int cg_path_get_user_unit(const char *path, char **unit) {
/* Skip slices, if there are any */
e = skip_slices(path);
/* Skip the session scope or user manager... */
t = skip_session(e);
/* Skip the user manager... */
t = skip_user_manager(e);
/* Alternatively skip the user session... */
if (!t)
t = skip_user_manager(e);
t = skip_session(e);
if (!t)
return -ENXIO;
/* ... and skip more slices if there are any */
e = skip_slices(t);
return cg_path_decode_unit(e, unit);
r = cg_path_decode_unit(e, &unit);
if (r < 0)
return r;
/* We skipped over the slices, don't accept any now */
if (endswith(unit, ".slice")) {
free(unit);
return -ENXIO;
}
*ret = unit;
return 0;
}
int cg_pid_get_user_unit(pid_t pid, char **unit) {
@ -1308,36 +1400,35 @@ int cg_pid_get_machine_name(pid_t pid, char **machine) {
}
int cg_path_get_session(const char *path, char **session) {
const char *e, *n, *x, *y;
char *s;
_cleanup_free_ char *unit = NULL;
char *start, *end;
int r;
assert(path);
/* Skip slices, if there are any */
e = skip_slices(path);
r = cg_path_get_unit(path, &unit);
if (r < 0)
return r;
n = strchrnul(e, '/');
if (e == n)
start = startswith(unit, "session-");
if (!start)
return -ENXIO;
end = endswith(start, ".scope");
if (!end)
return -ENXIO;
s = strndupa(e, n - e);
s = cg_unescape(s);
x = startswith(s, "session-");
if (!x)
return -ENXIO;
y = endswith(x, ".scope");
if (!y || x == y)
*end = 0;
if (!session_id_valid(start))
return -ENXIO;
if (session) {
char *r;
char *rr;
r = strndup(x, y - x);
if (!r)
rr = strdup(start);
if (!rr)
return -ENOMEM;
*session = r;
*session = rr;
}
return 0;
@ -1356,9 +1447,7 @@ int cg_pid_get_session(pid_t pid, char **session) {
int cg_path_get_owner_uid(const char *path, uid_t *uid) {
_cleanup_free_ char *slice = NULL;
const char *start, *end;
char *s;
uid_t u;
char *start, *end;
int r;
assert(path);
@ -1370,20 +1459,14 @@ int cg_path_get_owner_uid(const char *path, uid_t *uid) {
start = startswith(slice, "user-");
if (!start)
return -ENXIO;
end = endswith(slice, ".slice");
end = endswith(start, ".slice");
if (!end)
return -ENXIO;
s = strndupa(start, end - start);
if (!s)
*end = 0;
if (parse_uid(start, uid) < 0)
return -ENXIO;
if (parse_uid(s, &u) < 0)
return -ENXIO;
if (uid)
*uid = u;
return 0;
}
@ -1400,7 +1483,6 @@ int cg_pid_get_owner_uid(pid_t pid, uid_t *uid) {
int cg_path_get_slice(const char *p, char **slice) {
const char *e = NULL;
size_t m = 0;
assert(p);
assert(slice);
@ -1411,23 +1493,23 @@ int cg_path_get_slice(const char *p, char **slice) {
p += strspn(p, "/");
n = strcspn(p, "/");
if (n <= 6 || memcmp(p + n - 6, ".slice", 6) != 0) {
char *s;
if (!valid_slice_name(p, n)) {
if (!e)
return -ENXIO;
if (!e) {
char *s;
s = strndup(e, m);
if (!s)
return -ENOMEM;
s = strdup("-.slice");
if (!s)
return -ENOMEM;
*slice = s;
return 0;
*slice = s;
return 0;
}
return cg_path_decode_unit(e, slice);
}
e = p;
m = n;
p += n;
}
}

View File

@ -23,7 +23,9 @@
#include "def.h"
bool session_id_valid(const char *id) {
assert(id);
return id[0] && id[strspn(id, LETTERS DIGITS)] == '\0';
if (isempty(id))
return false;
return id[strspn(id, LETTERS DIGITS)] == '\0';
}

View File

@ -350,7 +350,6 @@ int parse_uid(const char *s, uid_t* ret_uid) {
int r;
assert(s);
assert(ret_uid);
r = safe_atolu(s, &ul);
if (r < 0)
@ -369,7 +368,9 @@ int parse_uid(const char *s, uid_t* ret_uid) {
if (uid == (uid_t) 0xFFFF)
return -ENXIO;
*ret_uid = uid;
if (ret_uid)
*ret_uid = uid;
return 0;
}

View File

@ -125,6 +125,23 @@ static void test_path_get_owner_uid(void) {
check_p_g_o_u("", -ENXIO, 0);
}
static void check_p_g_slice(const char *path, int code, const char *result) {
_cleanup_free_ char *s = NULL;
assert_se(cg_path_get_slice(path, &s) == code);
assert_se(streq_ptr(s, result));
}
static void test_path_get_slice(void) {
check_p_g_slice("/user.slice", 0, "user.slice");
check_p_g_slice("/foobar", 0, "-.slice");
check_p_g_slice("/user.slice/user-waldo.slice", 0, "user-waldo.slice");
check_p_g_slice("", 0, "-.slice");
check_p_g_slice("foobar", 0, "-.slice");
check_p_g_slice("foobar.slice", 0, "foobar.slice");
check_p_g_slice("foo.slice/foo-bar.slice/waldo.service", 0, "foo-bar.slice");
}
static void test_get_paths(void) {
_cleanup_free_ char *a = NULL;
@ -255,6 +272,7 @@ int main(void) {
test_path_get_user_unit();
test_path_get_session();
test_path_get_owner_uid();
test_path_get_slice();
TEST_REQ_RUNNING_SYSTEMD(test_get_paths());
test_proc();
TEST_REQ_RUNNING_SYSTEMD(test_escape());