Preface
-------
These patches are for binding the rlimit counters to a user in user namespace.
This patch set can be applied on top of:
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git v5.12-rc4
Problem
-------
The RLIMIT_NPROC, RLIMIT_MEMLOCK, RLIMIT_SIGPENDING, RLIMIT_MSGQUEUE rlimits
implementation places the counters in user_struct [1]. These limits are global
between processes and persists for the lifetime of the process, even if
processes are in different user namespaces.
To illustrate the impact of rlimits, let's say there is a program that does not
fork. Some service-A wants to run this program as user X in multiple containers.
Since the program never fork the service wants to set RLIMIT_NPROC=1.
service-A
\- program (uid=1000, container1, rlimit_nproc=1)
\- program (uid=1000, container2, rlimit_nproc=1)
The service-A sets RLIMIT_NPROC=1 and runs the program in container1. When the
service-A tries to run a program with RLIMIT_NPROC=1 in container2 it fails
since user X already has one running process.
The problem is not that the limit from container1 affects container2. The
problem is that limit is verified against the global counter that reflects
the number of processes in all containers.
This problem can be worked around by using different users for each container
but in this case we face a different problem of uid mapping when transferring
files from one container to another.
Eric W. Biederman mentioned this issue [2][3].
Introduced changes
------------------
To address the problem, we bind rlimit counters to user namespace. Each counter
reflects the number of processes in a given uid in a given user namespace. The
result is a tree of rlimit counters with the biggest value at the root (aka
init_user_ns). The limit is considered exceeded if it's exceeded up in the tree.
[1]: https://lore.kernel.org/containers/[email protected]/
[2]: https://lists.linuxfoundation.org/pipermail/containers/2020-August/042096.html
[3]: https://lists.linuxfoundation.org/pipermail/containers/2020-October/042524.html
Changelog
---------
v10:
* Fixed memory leak in __sigqueue_alloc.
* Handled an unlikely situation when all consumers will return ucounts at once.
* Addressed other review comments from Eric W. Biederman.
v9:
* Used a negative value to check that the ucounts->count is close to overflow.
* Rebased onto v5.12-rc4.
v8:
* Used atomic_t for ucounts reference counting. Also added counter overflow
check (thanks to Linus Torvalds for the idea).
* Fixed other issues found by lkp-tests project in the patch that Reimplements
RLIMIT_MEMLOCK on top of ucounts.
v7:
* Fixed issues found by lkp-tests project in the patch that Reimplements
RLIMIT_MEMLOCK on top of ucounts.
v6:
* Fixed issues found by lkp-tests project.
* Rebased onto v5.11.
v5:
* Split the first commit into two commits: change ucounts.count type to atomic_long_t
and add ucounts to cred. These commits were merged by mistake during the rebase.
* The __get_ucounts() renamed to alloc_ucounts().
* The cred.ucounts update has been moved from commit_creds() as it did not allow
to handle errors.
* Added error handling of set_cred_ucounts().
v4:
* Reverted the type change of ucounts.count to refcount_t.
* Fixed typo in the kernel/cred.c
v3:
* Added get_ucounts() function to increase the reference count. The existing
get_counts() function renamed to __get_ucounts().
* The type of ucounts.count changed from atomic_t to refcount_t.
* Dropped 'const' from set_cred_ucounts() arguments.
* Fixed a bug with freeing the cred structure after calling cred_alloc_blank().
* Commit messages have been updated.
* Added selftest.
v2:
* RLIMIT_MEMLOCK, RLIMIT_SIGPENDING and RLIMIT_MSGQUEUE are migrated to ucounts.
* Added ucounts for pair uid and user namespace into cred.
* Added the ability to increase ucount by more than 1.
v1:
* After discussion with Eric W. Biederman, I increased the size of ucounts to
atomic_long_t.
* Added ucount_max to avoid the fork bomb.
--
Alexey Gladkov (9):
Increase size of ucounts to atomic_long_t
Add a reference to ucounts for each cred
Use atomic_t for ucounts reference counting
Reimplement RLIMIT_NPROC on top of ucounts
Reimplement RLIMIT_MSGQUEUE on top of ucounts
Reimplement RLIMIT_SIGPENDING on top of ucounts
Reimplement RLIMIT_MEMLOCK on top of ucounts
kselftests: Add test to check for rlimit changes in different user
namespaces
ucounts: Set ucount_max to the largest positive value the type can
hold
fs/exec.c | 6 +-
fs/hugetlbfs/inode.c | 16 +-
fs/proc/array.c | 2 +-
include/linux/cred.h | 4 +
include/linux/hugetlb.h | 4 +-
include/linux/mm.h | 4 +-
include/linux/sched/user.h | 7 -
include/linux/shmem_fs.h | 2 +-
include/linux/signal_types.h | 4 +-
include/linux/user_namespace.h | 32 +++-
ipc/mqueue.c | 41 ++---
ipc/shm.c | 26 +--
kernel/cred.c | 50 +++++-
kernel/exit.c | 2 +-
kernel/fork.c | 18 +-
kernel/signal.c | 58 +++----
kernel/sys.c | 14 +-
kernel/ucount.c | 123 ++++++++++---
kernel/user.c | 3 -
kernel/user_namespace.c | 9 +-
mm/memfd.c | 4 +-
mm/mlock.c | 23 ++-
mm/mmap.c | 4 +-
mm/shmem.c | 8 +-
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/rlimits/.gitignore | 2 +
tools/testing/selftests/rlimits/Makefile | 6 +
tools/testing/selftests/rlimits/config | 1 +
.../selftests/rlimits/rlimits-per-userns.c | 161 ++++++++++++++++++
29 files changed, 490 insertions(+), 145 deletions(-)
create mode 100644 tools/testing/selftests/rlimits/.gitignore
create mode 100644 tools/testing/selftests/rlimits/Makefile
create mode 100644 tools/testing/selftests/rlimits/config
create mode 100644 tools/testing/selftests/rlimits/rlimits-per-userns.c
--
2.29.3
The rlimit counter is tied to uid in the user_namespace. This allows
rlimit values to be specified in userns even if they are already
globally exceeded by the user. However, the value of the previous
user_namespaces cannot be exceeded.
To illustrate the impact of rlimits, let's say there is a program that
does not fork. Some service-A wants to run this program as user X in
multiple containers. Since the program never fork the service wants to
set RLIMIT_NPROC=1.
service-A
\- program (uid=1000, container1, rlimit_nproc=1)
\- program (uid=1000, container2, rlimit_nproc=1)
The service-A sets RLIMIT_NPROC=1 and runs the program in container1.
When the service-A tries to run a program with RLIMIT_NPROC=1 in
container2 it fails since user X already has one running process.
We cannot use existing inc_ucounts / dec_ucounts because they do not
allow us to exceed the maximum for the counter. Some rlimits can be
overlimited by root or if the user has the appropriate capability.
Signed-off-by: Alexey Gladkov <[email protected]>
---
fs/exec.c | 2 +-
include/linux/cred.h | 2 ++
include/linux/sched/user.h | 1 -
include/linux/user_namespace.h | 13 +++++++++
kernel/cred.c | 10 +++----
kernel/exit.c | 2 +-
kernel/fork.c | 9 +++---
kernel/sys.c | 2 +-
kernel/ucount.c | 51 ++++++++++++++++++++++++++++++++++
kernel/user.c | 1 -
kernel/user_namespace.c | 3 +-
11 files changed, 81 insertions(+), 15 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index d7c4187ca023..f2bcdbeb3afb 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1878,7 +1878,7 @@ static int do_execveat_common(int fd, struct filename *filename,
* whether NPROC limit is still exceeded.
*/
if ((current->flags & PF_NPROC_EXCEEDED) &&
- atomic_read(¤t_user()->processes) > rlimit(RLIMIT_NPROC)) {
+ is_ucounts_overlimit(current_ucounts(), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
retval = -EAGAIN;
goto out_ret;
}
diff --git a/include/linux/cred.h b/include/linux/cred.h
index 66436e655032..5ca1e8a1d035 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -372,6 +372,7 @@ static inline void put_cred(const struct cred *_cred)
#define task_uid(task) (task_cred_xxx((task), uid))
#define task_euid(task) (task_cred_xxx((task), euid))
+#define task_ucounts(task) (task_cred_xxx((task), ucounts))
#define current_cred_xxx(xxx) \
({ \
@@ -388,6 +389,7 @@ static inline void put_cred(const struct cred *_cred)
#define current_fsgid() (current_cred_xxx(fsgid))
#define current_cap() (current_cred_xxx(cap_effective))
#define current_user() (current_cred_xxx(user))
+#define current_ucounts() (current_cred_xxx(ucounts))
extern struct user_namespace init_user_ns;
#ifdef CONFIG_USER_NS
diff --git a/include/linux/sched/user.h b/include/linux/sched/user.h
index a8ec3b6093fc..d33d867ad6c1 100644
--- a/include/linux/sched/user.h
+++ b/include/linux/sched/user.h
@@ -12,7 +12,6 @@
*/
struct user_struct {
refcount_t __count; /* reference count */
- atomic_t processes; /* How many processes does this user have? */
atomic_t sigpending; /* How many pending signals does this user have? */
#ifdef CONFIG_FANOTIFY
atomic_t fanotify_listeners;
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index d84cc2c0b443..9d1ca370c201 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -50,9 +50,12 @@ enum ucount_type {
UCOUNT_INOTIFY_INSTANCES,
UCOUNT_INOTIFY_WATCHES,
#endif
+ UCOUNT_RLIMIT_NPROC,
UCOUNT_COUNTS,
};
+#define MAX_PER_NAMESPACE_UCOUNTS UCOUNT_RLIMIT_NPROC
+
struct user_namespace {
struct uid_gid_map uid_map;
struct uid_gid_map gid_map;
@@ -107,6 +110,16 @@ struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid);
struct ucounts * __must_check get_ucounts(struct ucounts *ucounts);
void put_ucounts(struct ucounts *ucounts);
+static inline long get_ucounts_value(struct ucounts *ucounts, enum ucount_type type)
+{
+ return atomic_long_read(&ucounts->ucount[type]);
+}
+
+bool inc_rlimit_ucounts(struct ucounts *ucounts, enum ucount_type type, long v);
+bool inc_rlimit_ucounts_and_test(struct ucounts *ucounts, enum ucount_type type, long v, long max);
+void dec_rlimit_ucounts(struct ucounts *ucounts, enum ucount_type type, long v);
+bool is_ucounts_overlimit(struct ucounts *ucounts, enum ucount_type type, unsigned long max);
+
#ifdef CONFIG_USER_NS
static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
diff --git a/kernel/cred.c b/kernel/cred.c
index 58a8a9e24347..dcfa30b337c5 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -360,7 +360,7 @@ int copy_creds(struct task_struct *p, unsigned long clone_flags)
kdebug("share_creds(%p{%d,%d})",
p->cred, atomic_read(&p->cred->usage),
read_cred_subscribers(p->cred));
- atomic_inc(&p->cred->user->processes);
+ inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
return 0;
}
@@ -395,8 +395,8 @@ int copy_creds(struct task_struct *p, unsigned long clone_flags)
}
#endif
- atomic_inc(&new->user->processes);
p->cred = p->real_cred = get_cred(new);
+ inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
alter_cred_subscribers(new, 2);
validate_creds(new);
return 0;
@@ -496,12 +496,12 @@ int commit_creds(struct cred *new)
* in set_user().
*/
alter_cred_subscribers(new, 2);
- if (new->user != old->user)
- atomic_inc(&new->user->processes);
+ if (new->user != old->user || new->user_ns != old->user_ns)
+ inc_rlimit_ucounts(new->ucounts, UCOUNT_RLIMIT_NPROC, 1);
rcu_assign_pointer(task->real_cred, new);
rcu_assign_pointer(task->cred, new);
if (new->user != old->user)
- atomic_dec(&old->user->processes);
+ dec_rlimit_ucounts(old->ucounts, UCOUNT_RLIMIT_NPROC, 1);
alter_cred_subscribers(old, -2);
/* send notifications */
diff --git a/kernel/exit.c b/kernel/exit.c
index 04029e35e69a..61c0fe902b50 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -188,7 +188,7 @@ void release_task(struct task_struct *p)
/* don't need to get the RCU readlock here - the process is dead and
* can't be modifying its own credentials. But shut RCU-lockdep up */
rcu_read_lock();
- atomic_dec(&__task_cred(p)->user->processes);
+ dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
rcu_read_unlock();
cgroup_release(p);
diff --git a/kernel/fork.c b/kernel/fork.c
index 37498cca6a1d..d8a4956463ae 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -819,9 +819,11 @@ void __init fork_init(void)
init_task.signal->rlim[RLIMIT_SIGPENDING] =
init_task.signal->rlim[RLIMIT_NPROC];
- for (i = 0; i < UCOUNT_COUNTS; i++)
+ for (i = 0; i < MAX_PER_NAMESPACE_UCOUNTS; i++)
init_user_ns.ucount_max[i] = max_threads/2;
+ init_user_ns.ucount_max[UCOUNT_RLIMIT_NPROC] = task_rlimit(&init_task, RLIMIT_NPROC);
+
#ifdef CONFIG_VMAP_STACK
cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
NULL, free_vm_stack_cache);
@@ -1972,8 +1974,7 @@ static __latent_entropy struct task_struct *copy_process(
DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
#endif
retval = -EAGAIN;
- if (atomic_read(&p->real_cred->user->processes) >=
- task_rlimit(p, RLIMIT_NPROC)) {
+ if (is_ucounts_overlimit(task_ucounts(p), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
if (p->real_cred->user != INIT_USER &&
!capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
goto bad_fork_free;
@@ -2376,7 +2377,7 @@ static __latent_entropy struct task_struct *copy_process(
#endif
delayacct_tsk_free(p);
bad_fork_cleanup_count:
- atomic_dec(&p->cred->user->processes);
+ dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
exit_creds(p);
bad_fork_free:
p->state = TASK_DEAD;
diff --git a/kernel/sys.c b/kernel/sys.c
index cabfc5b86175..00266a65a000 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -473,7 +473,7 @@ static int set_user(struct cred *new)
* for programs doing set*uid()+execve() by harmlessly deferring the
* failure to the execve() stage.
*/
- if (atomic_read(&new_user->processes) >= rlimit(RLIMIT_NPROC) &&
+ if (is_ucounts_overlimit(new->ucounts, UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC)) &&
new_user != INIT_USER)
current->flags |= PF_NPROC_EXCEEDED;
else
diff --git a/kernel/ucount.c b/kernel/ucount.c
index 365865f368ec..d2c2f991ab3e 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -80,6 +80,7 @@ static struct ctl_table user_table[] = {
UCOUNT_ENTRY("max_inotify_instances"),
UCOUNT_ENTRY("max_inotify_watches"),
#endif
+ { },
{ }
};
#endif /* CONFIG_SYSCTL */
@@ -240,6 +241,55 @@ void dec_ucount(struct ucounts *ucounts, enum ucount_type type)
put_ucounts(ucounts);
}
+bool inc_rlimit_ucounts(struct ucounts *ucounts, enum ucount_type type, long v)
+{
+ struct ucounts *iter;
+ bool overlimit = false;
+
+ for (iter = ucounts; iter; iter = iter->ns->ucounts) {
+ long max = READ_ONCE(iter->ns->ucount_max[type]);
+ long new = atomic_long_add_return(v, &iter->ucount[type]);
+ if (new < 0 || new > max)
+ overlimit = true;
+ }
+
+ return overlimit;
+}
+
+bool inc_rlimit_ucounts_and_test(struct ucounts *ucounts, enum ucount_type type,
+ long v, long max)
+{
+ bool overlimit = inc_rlimit_ucounts(ucounts, type, v);
+ if (!overlimit) {
+ long new = get_ucounts_value(ucounts, type);
+ if ( new < 0 || new > max)
+ overlimit = true;
+ }
+ return overlimit;
+}
+
+void dec_rlimit_ucounts(struct ucounts *ucounts, enum ucount_type type, long v)
+{
+ struct ucounts *iter;
+ for (iter = ucounts; iter; iter = iter->ns->ucounts) {
+ long dec = atomic_long_add_return(-v, &iter->ucount[type]);
+ WARN_ON_ONCE(dec < 0);
+ }
+}
+
+bool is_ucounts_overlimit(struct ucounts *ucounts, enum ucount_type type, unsigned long max)
+{
+ struct ucounts *iter;
+ if (get_ucounts_value(ucounts, type) > max)
+ return true;
+ for (iter = ucounts; iter; iter = iter->ns->ucounts) {
+ max = READ_ONCE(iter->ns->ucount_max[type]);
+ if (get_ucounts_value(iter, type) > max)
+ return true;
+ }
+ return false;
+}
+
static __init int user_namespace_sysctl_init(void)
{
#ifdef CONFIG_SYSCTL
@@ -256,6 +306,7 @@ static __init int user_namespace_sysctl_init(void)
BUG_ON(!setup_userns_sysctls(&init_user_ns));
#endif
hlist_add_ucounts(&init_ucounts);
+ inc_rlimit_ucounts(&init_ucounts, UCOUNT_RLIMIT_NPROC, 1);
return 0;
}
subsys_initcall(user_namespace_sysctl_init);
diff --git a/kernel/user.c b/kernel/user.c
index a2478cddf536..7f5ff498207a 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -98,7 +98,6 @@ static DEFINE_SPINLOCK(uidhash_lock);
/* root_user.__count is 1, for init task cred */
struct user_struct root_user = {
.__count = REFCOUNT_INIT(1),
- .processes = ATOMIC_INIT(1),
.sigpending = ATOMIC_INIT(0),
.locked_shm = 0,
.uid = GLOBAL_ROOT_UID,
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 516db53166ab..2434b13b02e5 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -118,9 +118,10 @@ int create_user_ns(struct cred *new)
ns->owner = owner;
ns->group = group;
INIT_WORK(&ns->work, free_user_ns);
- for (i = 0; i < UCOUNT_COUNTS; i++) {
+ for (i = 0; i < MAX_PER_NAMESPACE_UCOUNTS; i++) {
ns->ucount_max[i] = INT_MAX;
}
+ ns->ucount_max[UCOUNT_RLIMIT_NPROC] = rlimit(RLIMIT_NPROC);
ns->ucounts = ucounts;
/* Inherit USERNS_SETGROUPS_ALLOWED from our parent */
--
2.29.3
RLIMIT_MSGQUEUE and RLIMIT_MEMLOCK use unsigned long to store their
counters. As a preparation for moving rlimits based on ucounts, we need
to increase the size of the variable to long.
Signed-off-by: Alexey Gladkov <[email protected]>
---
include/linux/user_namespace.h | 4 ++--
kernel/ucount.c | 16 ++++++++--------
2 files changed, 10 insertions(+), 10 deletions(-)
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 64cf8ebdc4ec..0bb833fd41f4 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -85,7 +85,7 @@ struct user_namespace {
struct ctl_table_header *sysctls;
#endif
struct ucounts *ucounts;
- int ucount_max[UCOUNT_COUNTS];
+ long ucount_max[UCOUNT_COUNTS];
} __randomize_layout;
struct ucounts {
@@ -93,7 +93,7 @@ struct ucounts {
struct user_namespace *ns;
kuid_t uid;
int count;
- atomic_t ucount[UCOUNT_COUNTS];
+ atomic_long_t ucount[UCOUNT_COUNTS];
};
extern struct user_namespace init_user_ns;
diff --git a/kernel/ucount.c b/kernel/ucount.c
index 11b1596e2542..04c561751af1 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -175,14 +175,14 @@ static void put_ucounts(struct ucounts *ucounts)
kfree(ucounts);
}
-static inline bool atomic_inc_below(atomic_t *v, int u)
+static inline bool atomic_long_inc_below(atomic_long_t *v, int u)
{
- int c, old;
- c = atomic_read(v);
+ long c, old;
+ c = atomic_long_read(v);
for (;;) {
if (unlikely(c >= u))
return false;
- old = atomic_cmpxchg(v, c, c+1);
+ old = atomic_long_cmpxchg(v, c, c+1);
if (likely(old == c))
return true;
c = old;
@@ -196,17 +196,17 @@ struct ucounts *inc_ucount(struct user_namespace *ns, kuid_t uid,
struct user_namespace *tns;
ucounts = get_ucounts(ns, uid);
for (iter = ucounts; iter; iter = tns->ucounts) {
- int max;
+ long max;
tns = iter->ns;
max = READ_ONCE(tns->ucount_max[type]);
- if (!atomic_inc_below(&iter->ucount[type], max))
+ if (!atomic_long_inc_below(&iter->ucount[type], max))
goto fail;
}
return ucounts;
fail:
bad = iter;
for (iter = ucounts; iter != bad; iter = iter->ns->ucounts)
- atomic_dec(&iter->ucount[type]);
+ atomic_long_dec(&iter->ucount[type]);
put_ucounts(ucounts);
return NULL;
@@ -216,7 +216,7 @@ void dec_ucount(struct ucounts *ucounts, enum ucount_type type)
{
struct ucounts *iter;
for (iter = ucounts; iter; iter = iter->ns->ucounts) {
- int dec = atomic_dec_if_positive(&iter->ucount[type]);
+ long dec = atomic_long_dec_if_positive(&iter->ucount[type]);
WARN_ON_ONCE(dec < 0);
}
put_ucounts(ucounts);
--
2.29.3
The testcase runs few instances of the program with RLIMIT_NPROC=1 from
user uid=60000, in different user namespaces.
Signed-off-by: Alexey Gladkov <[email protected]>
---
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/rlimits/.gitignore | 2 +
tools/testing/selftests/rlimits/Makefile | 6 +
tools/testing/selftests/rlimits/config | 1 +
.../selftests/rlimits/rlimits-per-userns.c | 161 ++++++++++++++++++
5 files changed, 171 insertions(+)
create mode 100644 tools/testing/selftests/rlimits/.gitignore
create mode 100644 tools/testing/selftests/rlimits/Makefile
create mode 100644 tools/testing/selftests/rlimits/config
create mode 100644 tools/testing/selftests/rlimits/rlimits-per-userns.c
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 6c575cf34a71..a4ea1481bd9a 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -48,6 +48,7 @@ TARGETS += proc
TARGETS += pstore
TARGETS += ptrace
TARGETS += openat2
+TARGETS += rlimits
TARGETS += rseq
TARGETS += rtc
TARGETS += seccomp
diff --git a/tools/testing/selftests/rlimits/.gitignore b/tools/testing/selftests/rlimits/.gitignore
new file mode 100644
index 000000000000..091021f255b3
--- /dev/null
+++ b/tools/testing/selftests/rlimits/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+rlimits-per-userns
diff --git a/tools/testing/selftests/rlimits/Makefile b/tools/testing/selftests/rlimits/Makefile
new file mode 100644
index 000000000000..03aadb406212
--- /dev/null
+++ b/tools/testing/selftests/rlimits/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+CFLAGS += -Wall -O2 -g
+TEST_GEN_PROGS := rlimits-per-userns
+
+include ../lib.mk
diff --git a/tools/testing/selftests/rlimits/config b/tools/testing/selftests/rlimits/config
new file mode 100644
index 000000000000..416bd53ce982
--- /dev/null
+++ b/tools/testing/selftests/rlimits/config
@@ -0,0 +1 @@
+CONFIG_USER_NS=y
diff --git a/tools/testing/selftests/rlimits/rlimits-per-userns.c b/tools/testing/selftests/rlimits/rlimits-per-userns.c
new file mode 100644
index 000000000000..26dc949e93ea
--- /dev/null
+++ b/tools/testing/selftests/rlimits/rlimits-per-userns.c
@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Author: Alexey Gladkov <[email protected]>
+ */
+#define _GNU_SOURCE
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/time.h>
+#include <sys/resource.h>
+#include <sys/prctl.h>
+#include <sys/stat.h>
+
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <sched.h>
+#include <signal.h>
+#include <limits.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <err.h>
+
+#define NR_CHILDS 2
+
+static char *service_prog;
+static uid_t user = 60000;
+static uid_t group = 60000;
+
+static void setrlimit_nproc(rlim_t n)
+{
+ pid_t pid = getpid();
+ struct rlimit limit = {
+ .rlim_cur = n,
+ .rlim_max = n
+ };
+
+ warnx("(pid=%d): Setting RLIMIT_NPROC=%ld", pid, n);
+
+ if (setrlimit(RLIMIT_NPROC, &limit) < 0)
+ err(EXIT_FAILURE, "(pid=%d): setrlimit(RLIMIT_NPROC)", pid);
+}
+
+static pid_t fork_child(void)
+{
+ pid_t pid = fork();
+
+ if (pid < 0)
+ err(EXIT_FAILURE, "fork");
+
+ if (pid > 0)
+ return pid;
+
+ pid = getpid();
+
+ warnx("(pid=%d): New process starting ...", pid);
+
+ if (prctl(PR_SET_PDEATHSIG, SIGKILL) < 0)
+ err(EXIT_FAILURE, "(pid=%d): prctl(PR_SET_PDEATHSIG)", pid);
+
+ signal(SIGUSR1, SIG_DFL);
+
+ warnx("(pid=%d): Changing to uid=%d, gid=%d", pid, user, group);
+
+ if (setgid(group) < 0)
+ err(EXIT_FAILURE, "(pid=%d): setgid(%d)", pid, group);
+ if (setuid(user) < 0)
+ err(EXIT_FAILURE, "(pid=%d): setuid(%d)", pid, user);
+
+ warnx("(pid=%d): Service running ...", pid);
+
+ warnx("(pid=%d): Unshare user namespace", pid);
+ if (unshare(CLONE_NEWUSER) < 0)
+ err(EXIT_FAILURE, "unshare(CLONE_NEWUSER)");
+
+ char *const argv[] = { "service", NULL };
+ char *const envp[] = { "I_AM_SERVICE=1", NULL };
+
+ warnx("(pid=%d): Executing real service ...", pid);
+
+ execve(service_prog, argv, envp);
+ err(EXIT_FAILURE, "(pid=%d): execve", pid);
+}
+
+int main(int argc, char **argv)
+{
+ size_t i;
+ pid_t child[NR_CHILDS];
+ int wstatus[NR_CHILDS];
+ int childs = NR_CHILDS;
+ pid_t pid;
+
+ if (getenv("I_AM_SERVICE")) {
+ pause();
+ exit(EXIT_SUCCESS);
+ }
+
+ service_prog = argv[0];
+ pid = getpid();
+
+ warnx("(pid=%d) Starting testcase", pid);
+
+ /*
+ * This rlimit is not a problem for root because it can be exceeded.
+ */
+ setrlimit_nproc(1);
+
+ for (i = 0; i < NR_CHILDS; i++) {
+ child[i] = fork_child();
+ wstatus[i] = 0;
+ usleep(250000);
+ }
+
+ while (1) {
+ for (i = 0; i < NR_CHILDS; i++) {
+ if (child[i] <= 0)
+ continue;
+
+ errno = 0;
+ pid_t ret = waitpid(child[i], &wstatus[i], WNOHANG);
+
+ if (!ret || (!WIFEXITED(wstatus[i]) && !WIFSIGNALED(wstatus[i])))
+ continue;
+
+ if (ret < 0 && errno != ECHILD)
+ warn("(pid=%d): waitpid(%d)", pid, child[i]);
+
+ child[i] *= -1;
+ childs -= 1;
+ }
+
+ if (!childs)
+ break;
+
+ usleep(250000);
+
+ for (i = 0; i < NR_CHILDS; i++) {
+ if (child[i] <= 0)
+ continue;
+ kill(child[i], SIGUSR1);
+ }
+ }
+
+ for (i = 0; i < NR_CHILDS; i++) {
+ if (WIFEXITED(wstatus[i]))
+ warnx("(pid=%d): pid %d exited, status=%d",
+ pid, -child[i], WEXITSTATUS(wstatus[i]));
+ else if (WIFSIGNALED(wstatus[i]))
+ warnx("(pid=%d): pid %d killed by signal %d",
+ pid, -child[i], WTERMSIG(wstatus[i]));
+
+ if (WIFSIGNALED(wstatus[i]) && WTERMSIG(wstatus[i]) == SIGUSR1)
+ continue;
+
+ warnx("(pid=%d): Test failed", pid);
+ exit(EXIT_FAILURE);
+ }
+
+ warnx("(pid=%d): Test passed", pid);
+ exit(EXIT_SUCCESS);
+}
--
2.29.3