* [PATCH v5 1/7] Increase size of ucounts to atomic_long_t
2021-02-01 14:18 [PATCH v5 0/7] Count rlimits in each user namespace Alexey Gladkov
@ 2021-02-01 14:18 ` Alexey Gladkov
2021-02-01 14:18 ` [PATCH v5 2/7] Add a reference to ucounts for each cred Alexey Gladkov
` (5 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: Alexey Gladkov @ 2021-02-01 14:18 UTC (permalink / raw)
To: LKML, io-uring, Kernel Hardening, Linux Containers, linux-mm
Cc: Alexey Gladkov, Andrew Morton, Christian Brauner,
Eric W . Biederman, Jann Horn, Jens Axboe, Kees Cook,
Linus Torvalds, Oleg Nesterov
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);
--
2.29.2
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH v5 2/7] Add a reference to ucounts for each cred
2021-02-01 14:18 [PATCH v5 0/7] Count rlimits in each user namespace Alexey Gladkov
2021-02-01 14:18 ` [PATCH v5 1/7] Increase size of ucounts to atomic_long_t Alexey Gladkov
@ 2021-02-01 14:18 ` Alexey Gladkov
2021-02-01 14:18 ` [PATCH v5 3/7] Reimplement RLIMIT_NPROC on top of ucounts Alexey Gladkov
` (4 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: Alexey Gladkov @ 2021-02-01 14:18 UTC (permalink / raw)
To: LKML, io-uring, Kernel Hardening, Linux Containers, linux-mm
Cc: Alexey Gladkov, Andrew Morton, Christian Brauner,
Eric W . Biederman, Jann Horn, Jens Axboe, Kees Cook,
Linus Torvalds, Oleg Nesterov
For RLIMIT_NPROC and some other rlimits the user_struct that holds the
global limit is kept alive for the lifetime of a process by keeping it
in struct cred. Adding a pointer to ucounts in the struct cred will
allow to track RLIMIT_NPROC not only for user in the system, but for
user in the user_namespace.
Updating ucounts may require memory allocation which may fail. So, we
cannot change cred.ucounts in the commit_creds() because this function
cannot fail and it should always return 0. For this reason, we modify
cred.ucounts before calling the commit_creds().
Signed-off-by: Alexey Gladkov <[email protected]>
---
fs/exec.c | 4 +++
include/linux/cred.h | 2 ++
include/linux/user_namespace.h | 3 +++
kernel/cred.c | 45 ++++++++++++++++++++++++++++++++++
kernel/fork.c | 6 +++++
kernel/sys.c | 12 +++++++++
kernel/ucount.c | 26 +++++++++++++++++---
kernel/user_namespace.c | 3 +++
8 files changed, 98 insertions(+), 3 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index 5d4d52039105..0371a3400be5 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1360,6 +1360,10 @@ int begin_new_exec(struct linux_binprm * bprm)
WRITE_ONCE(me->self_exec_id, me->self_exec_id + 1);
flush_signal_handlers(me, 0);
+ retval = set_cred_ucounts(bprm->cred);
+ if (retval < 0)
+ goto out_unlock;
+
/*
* install the new credentials for this executable
*/
diff --git a/include/linux/cred.h b/include/linux/cred.h
index 18639c069263..ad160e5fe5c6 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -144,6 +144,7 @@ struct cred {
#endif
struct user_struct *user; /* real user ID subscription */
struct user_namespace *user_ns; /* user_ns the caps and keyrings are relative to. */
+ struct ucounts *ucounts;
struct group_info *group_info; /* supplementary groups for euid/fsgid */
/* RCU deletion */
union {
@@ -170,6 +171,7 @@ extern int set_security_override_from_ctx(struct cred *, const char *);
extern int set_create_files_as(struct cred *, struct inode *);
extern int cred_fscmp(const struct cred *, const struct cred *);
extern void __init cred_init(void);
+extern int set_cred_ucounts(struct cred *);
/*
* check for validity of credentials
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 0bb833fd41f4..43f5847cc897 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -102,6 +102,9 @@ bool setup_userns_sysctls(struct user_namespace *ns);
void retire_userns_sysctls(struct user_namespace *ns);
struct ucounts *inc_ucount(struct user_namespace *ns, kuid_t uid, enum ucount_type type);
void dec_ucount(struct ucounts *ucounts, enum ucount_type type);
+struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid);
+struct ucounts *get_ucounts(struct ucounts *ucounts);
+void put_ucounts(struct ucounts *ucounts);
#ifdef CONFIG_USER_NS
diff --git a/kernel/cred.c b/kernel/cred.c
index 421b1149c651..8194a59e283f 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -119,6 +119,8 @@ static void put_cred_rcu(struct rcu_head *rcu)
if (cred->group_info)
put_group_info(cred->group_info);
free_uid(cred->user);
+ if (cred->ucounts)
+ put_ucounts(cred->ucounts);
put_user_ns(cred->user_ns);
kmem_cache_free(cred_jar, cred);
}
@@ -284,6 +286,11 @@ struct cred *prepare_creds(void)
if (security_prepare_creds(new, old, GFP_KERNEL_ACCOUNT) < 0)
goto error;
+
+ new->ucounts = get_ucounts(new->ucounts);
+ if (!new->ucounts)
+ goto error;
+
validate_creds(new);
return new;
@@ -363,6 +370,8 @@ int copy_creds(struct task_struct *p, unsigned long clone_flags)
ret = create_user_ns(new);
if (ret < 0)
goto error_put;
+ if (set_cred_ucounts(new) < 0)
+ goto error_put;
}
#ifdef CONFIG_KEYS
@@ -653,6 +662,33 @@ int cred_fscmp(const struct cred *a, const struct cred *b)
}
EXPORT_SYMBOL(cred_fscmp);
+int set_cred_ucounts(struct cred *new)
+{
+ struct task_struct *task = current;
+ const struct cred *old = task->real_cred;
+ struct ucounts *old_ucounts = new->ucounts;
+
+ BUG_ON(task->cred != old);
+
+ if (new->user == old->user && new->user_ns == old->user_ns)
+ return 0;
+
+ /*
+ * This optimization is needed because alloc_ucounts() uses locks
+ * for table lookups.
+ */
+ if (old_ucounts && old_ucounts->ns == new->user_ns && uid_eq(old_ucounts->uid, new->euid))
+ return 0;
+
+ if (!(new->ucounts = alloc_ucounts(new->user_ns, new->euid)))
+ return -EAGAIN;
+
+ if (old_ucounts)
+ put_ucounts(old_ucounts);
+
+ return 0;
+}
+
/*
* initialise the credentials stuff
*/
@@ -661,6 +697,11 @@ void __init cred_init(void)
/* allocate a slab in which we can store credentials */
cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred), 0,
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL);
+ /*
+ * This is needed here because this is the first cred and there is no
+ * ucount reference to copy.
+ */
+ init_cred.ucounts = alloc_ucounts(init_cred.user_ns, init_cred.euid);
}
/**
@@ -719,6 +760,10 @@ struct cred *prepare_kernel_cred(struct task_struct *daemon)
if (security_prepare_creds(new, old, GFP_KERNEL_ACCOUNT) < 0)
goto error;
+ new->ucounts = get_ucounts(new->ucounts);
+ if (!new->ucounts)
+ goto error;
+
put_cred(old);
validate_creds(new);
return new;
diff --git a/kernel/fork.c b/kernel/fork.c
index 37720a6d04ea..b0d36dea0a9c 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2959,6 +2959,12 @@ int ksys_unshare(unsigned long unshare_flags)
if (err)
goto bad_unshare_cleanup_cred;
+ if (new_cred) {
+ err = set_cred_ucounts(new_cred);
+ if (err)
+ goto bad_unshare_cleanup_cred;
+ }
+
if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) {
if (do_sysvsem) {
/*
diff --git a/kernel/sys.c b/kernel/sys.c
index 51f00fe20e4d..373def7debe8 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -553,6 +553,10 @@ long __sys_setreuid(uid_t ruid, uid_t euid)
if (retval < 0)
goto error;
+ retval = set_cred_ucounts(new);
+ if (retval < 0)
+ goto error;
+
return commit_creds(new);
error:
@@ -611,6 +615,10 @@ long __sys_setuid(uid_t uid)
if (retval < 0)
goto error;
+ retval = set_cred_ucounts(new);
+ if (retval < 0)
+ goto error;
+
return commit_creds(new);
error:
@@ -686,6 +694,10 @@ long __sys_setresuid(uid_t ruid, uid_t euid, uid_t suid)
if (retval < 0)
goto error;
+ retval = set_cred_ucounts(new);
+ if (retval < 0)
+ goto error;
+
return commit_creds(new);
error:
diff --git a/kernel/ucount.c b/kernel/ucount.c
index 04c561751af1..9644bced74b4 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -125,7 +125,7 @@ static struct ucounts *find_ucounts(struct user_namespace *ns, kuid_t uid, struc
return NULL;
}
-static struct ucounts *get_ucounts(struct user_namespace *ns, kuid_t uid)
+struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid)
{
struct hlist_head *hashent = ucounts_hashentry(ns, uid);
struct ucounts *ucounts, *new;
@@ -160,11 +160,31 @@ static struct ucounts *get_ucounts(struct user_namespace *ns, kuid_t uid)
return ucounts;
}
-static void put_ucounts(struct ucounts *ucounts)
+struct ucounts *get_ucounts(struct ucounts *ucounts)
+{
+ unsigned long flags;
+
+ if (!ucounts)
+ return NULL;
+
+ spin_lock_irqsave(&ucounts_lock, flags);
+ if (ucounts->count == INT_MAX) {
+ WARN_ONCE(1, "ucounts: counter has reached its maximum value");
+ ucounts = NULL;
+ } else {
+ ucounts->count += 1;
+ }
+ spin_unlock_irqrestore(&ucounts_lock, flags);
+
+ return ucounts;
+}
+
+void put_ucounts(struct ucounts *ucounts)
{
unsigned long flags;
spin_lock_irqsave(&ucounts_lock, flags);
+ BUG_ON(ucounts->count <= 0);
ucounts->count -= 1;
if (!ucounts->count)
hlist_del_init(&ucounts->node);
@@ -194,7 +214,7 @@ struct ucounts *inc_ucount(struct user_namespace *ns, kuid_t uid,
{
struct ucounts *ucounts, *iter, *bad;
struct user_namespace *tns;
- ucounts = get_ucounts(ns, uid);
+ ucounts = alloc_ucounts(ns, uid);
for (iter = ucounts; iter; iter = tns->ucounts) {
long max;
tns = iter->ns;
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index af612945a4d0..516db53166ab 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -1281,6 +1281,9 @@ static int userns_install(struct nsset *nsset, struct ns_common *ns)
put_user_ns(cred->user_ns);
set_cred_user_ns(cred, get_user_ns(user_ns));
+ if (set_cred_ucounts(cred) < 0)
+ return -EINVAL;
+
return 0;
}
--
2.29.2
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH v5 3/7] Reimplement RLIMIT_NPROC on top of ucounts
2021-02-01 14:18 [PATCH v5 0/7] Count rlimits in each user namespace Alexey Gladkov
2021-02-01 14:18 ` [PATCH v5 1/7] Increase size of ucounts to atomic_long_t Alexey Gladkov
2021-02-01 14:18 ` [PATCH v5 2/7] Add a reference to ucounts for each cred Alexey Gladkov
@ 2021-02-01 14:18 ` Alexey Gladkov
2021-02-01 14:18 ` [PATCH v5 4/7] Reimplement RLIMIT_MSGQUEUE " Alexey Gladkov
` (3 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: Alexey Gladkov @ 2021-02-01 14:18 UTC (permalink / raw)
To: LKML, io-uring, Kernel Hardening, Linux Containers, linux-mm
Cc: Alexey Gladkov, Andrew Morton, Christian Brauner,
Eric W . Biederman, Jann Horn, Jens Axboe, Kees Cook,
Linus Torvalds, Oleg Nesterov
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 +-
fs/io-wq.c | 22 ++++++-------
fs/io-wq.h | 2 +-
fs/io_uring.c | 2 +-
include/linux/cred.h | 2 ++
include/linux/sched/user.h | 1 -
include/linux/user_namespace.h | 13 ++++++++
kernel/cred.c | 11 ++++---
kernel/exit.c | 2 +-
kernel/fork.c | 9 ++---
kernel/sys.c | 2 +-
kernel/ucount.c | 60 ++++++++++++++++++++++++++++++++++
kernel/user.c | 1 -
kernel/user_namespace.c | 3 +-
14 files changed, 103 insertions(+), 29 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index 0371a3400be5..e6d7f186f33c 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1874,7 +1874,7 @@ 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/fs/io-wq.c b/fs/io-wq.c
index a564f36e260c..5b6940c90c61 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -20,6 +20,7 @@
#include <linux/blk-cgroup.h>
#include <linux/audit.h>
#include <linux/cpu.h>
+#include <linux/user_namespace.h>
#include "../kernel/sched/sched.h"
#include "io-wq.h"
@@ -120,7 +121,7 @@ struct io_wq {
io_wq_work_fn *do_work;
struct task_struct *manager;
- struct user_struct *user;
+ const struct cred *cred;
refcount_t refs;
struct completion done;
@@ -234,7 +235,7 @@ static void io_worker_exit(struct io_worker *worker)
if (worker->flags & IO_WORKER_F_RUNNING)
atomic_dec(&acct->nr_running);
if (!(worker->flags & IO_WORKER_F_BOUND))
- atomic_dec(&wqe->wq->user->processes);
+ dec_rlimit_ucounts(wqe->wq->cred->ucounts, UCOUNT_RLIMIT_NPROC, 1);
worker->flags = 0;
preempt_enable();
@@ -364,15 +365,15 @@ static void __io_worker_busy(struct io_wqe *wqe, struct io_worker *worker,
worker->flags |= IO_WORKER_F_BOUND;
wqe->acct[IO_WQ_ACCT_UNBOUND].nr_workers--;
wqe->acct[IO_WQ_ACCT_BOUND].nr_workers++;
- atomic_dec(&wqe->wq->user->processes);
+ dec_rlimit_ucounts(wqe->wq->cred->ucounts, UCOUNT_RLIMIT_NPROC, 1);
} else {
worker->flags &= ~IO_WORKER_F_BOUND;
wqe->acct[IO_WQ_ACCT_UNBOUND].nr_workers++;
wqe->acct[IO_WQ_ACCT_BOUND].nr_workers--;
- atomic_inc(&wqe->wq->user->processes);
+ inc_rlimit_ucounts(wqe->wq->cred->ucounts, UCOUNT_RLIMIT_NPROC, 1);
}
io_wqe_inc_running(wqe, worker);
- }
+ }
}
/*
@@ -707,7 +708,7 @@ static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index)
raw_spin_unlock_irq(&wqe->lock);
if (index == IO_WQ_ACCT_UNBOUND)
- atomic_inc(&wq->user->processes);
+ inc_rlimit_ucounts(wq->cred->ucounts, UCOUNT_RLIMIT_NPROC, 1);
refcount_inc(&wq->refs);
wake_up_process(worker->task);
@@ -838,7 +839,7 @@ static bool io_wq_can_queue(struct io_wqe *wqe, struct io_wqe_acct *acct,
if (free_worker)
return true;
- if (atomic_read(&wqe->wq->user->processes) >= acct->max_workers &&
+ if (is_ucounts_overlimit(wqe->wq->cred->ucounts, UCOUNT_RLIMIT_NPROC, acct->max_workers) &&
!(capable(CAP_SYS_RESOURCE) || capable(CAP_SYS_ADMIN)))
return false;
@@ -1074,7 +1075,7 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
wq->do_work = data->do_work;
/* caller must already hold a reference to this */
- wq->user = data->user;
+ wq->cred = data->cred;
ret = -ENOMEM;
for_each_node(node) {
@@ -1090,10 +1091,7 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
wqe->node = alloc_node;
wqe->acct[IO_WQ_ACCT_BOUND].max_workers = bounded;
atomic_set(&wqe->acct[IO_WQ_ACCT_BOUND].nr_running, 0);
- if (wq->user) {
- wqe->acct[IO_WQ_ACCT_UNBOUND].max_workers =
- task_rlimit(current, RLIMIT_NPROC);
- }
+ wqe->acct[IO_WQ_ACCT_UNBOUND].max_workers = task_rlimit(current, RLIMIT_NPROC);
atomic_set(&wqe->acct[IO_WQ_ACCT_UNBOUND].nr_running, 0);
wqe->wq = wq;
raw_spin_lock_init(&wqe->lock);
diff --git a/fs/io-wq.h b/fs/io-wq.h
index b158f8addcf3..4130e247c556 100644
--- a/fs/io-wq.h
+++ b/fs/io-wq.h
@@ -111,7 +111,7 @@ typedef void (free_work_fn)(struct io_wq_work *);
typedef struct io_wq_work *(io_wq_work_fn)(struct io_wq_work *);
struct io_wq_data {
- struct user_struct *user;
+ const struct cred *cred;
io_wq_work_fn *do_work;
free_work_fn *free_work;
diff --git a/fs/io_uring.c b/fs/io_uring.c
index ca46f314640b..7e463dd5f3d0 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7985,7 +7985,7 @@ static int io_init_wq_offload(struct io_ring_ctx *ctx,
unsigned int concurrency;
int ret = 0;
- data.user = ctx->user;
+ data.cred = ctx->creds;
data.free_work = io_free_work;
data.do_work = io_wq_submit_work;
diff --git a/include/linux/cred.h b/include/linux/cred.h
index ad160e5fe5c6..8025fe48198f 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 43f5847cc897..bca7ba20f552 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;
@@ -106,6 +109,16 @@ struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid);
struct ucounts *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, 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 8194a59e283f..05b215c490b0 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -358,7 +358,7 @@ 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;
}
@@ -393,8 +393,8 @@ 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;
@@ -494,12 +494,12 @@ 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 */
@@ -702,6 +702,7 @@ void __init cred_init(void)
* ucount reference to copy.
*/
init_cred.ucounts = alloc_ucounts(init_cred.user_ns, init_cred.euid);
+ inc_rlimit_ucounts(init_cred.ucounts, UCOUNT_RLIMIT_NPROC, 1);
}
/**
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 b0d36dea0a9c..d50a720adbf1 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -819,10 +819,12 @@ 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);
@@ -1964,8 +1966,7 @@ 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;
@@ -2368,7 +2369,7 @@ 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 373def7debe8..304b6b5e5942 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -474,7 +474,7 @@ 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 9644bced74b4..8f5bc29ac453 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -7,6 +7,7 @@
#include <linux/hash.h>
#include <linux/kmemleak.h>
#include <linux/user_namespace.h>
+#include <linux/security.h>
#define UCOUNTS_HASHTABLE_BITS 10
static struct hlist_head ucounts_hashtable[(1 << UCOUNTS_HASHTABLE_BITS)];
@@ -74,6 +75,7 @@ static struct ctl_table user_table[] = {
UCOUNT_ENTRY("max_inotify_instances"),
UCOUNT_ENTRY("max_inotify_watches"),
#endif
+ { },
{ }
};
#endif /* CONFIG_SYSCTL */
@@ -209,6 +211,19 @@ static inline bool atomic_long_inc_below(atomic_long_t *v, int u)
}
}
+static inline long atomic_long_dec_value(atomic_long_t *v, long n)
+{
+ long c, old;
+ c = atomic_long_read(v);
+ for (;;) {
+ old = atomic_long_cmpxchg(v, c, c - n);
+ if (likely(old == c))
+ return c;
+ c = old;
+ }
+ return c;
+}
+
struct ucounts *inc_ucount(struct user_namespace *ns, kuid_t uid,
enum ucount_type type)
{
@@ -242,6 +257,51 @@ 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]);
+ if (atomic_long_add_return(v, &iter->ucount[type]) > 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 && get_ucounts_value(ucounts, type) > 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_dec_value(&iter->ucount[type], v);
+ WARN_ON_ONCE(dec < 0);
+ }
+}
+
+bool is_ucounts_overlimit(struct ucounts *ucounts, enum ucount_type type, 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
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 */
--
2.29.2
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH v5 4/7] Reimplement RLIMIT_MSGQUEUE on top of ucounts
2021-02-01 14:18 [PATCH v5 0/7] Count rlimits in each user namespace Alexey Gladkov
` (2 preceding siblings ...)
2021-02-01 14:18 ` [PATCH v5 3/7] Reimplement RLIMIT_NPROC on top of ucounts Alexey Gladkov
@ 2021-02-01 14:18 ` Alexey Gladkov
2021-02-01 14:18 ` [PATCH v5 5/7] Reimplement RLIMIT_SIGPENDING " Alexey Gladkov
` (2 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: Alexey Gladkov @ 2021-02-01 14:18 UTC (permalink / raw)
To: LKML, io-uring, Kernel Hardening, Linux Containers, linux-mm
Cc: Alexey Gladkov, Andrew Morton, Christian Brauner,
Eric W . Biederman, Jann Horn, Jens Axboe, Kees Cook,
Linus Torvalds, Oleg Nesterov
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.
Signed-off-by: Alexey Gladkov <[email protected]>
---
include/linux/sched/user.h | 4 ----
include/linux/user_namespace.h | 1 +
ipc/mqueue.c | 29 +++++++++++++++--------------
kernel/fork.c | 1 +
kernel/ucount.c | 1 +
kernel/user_namespace.c | 1 +
6 files changed, 19 insertions(+), 18 deletions(-)
diff --git a/include/linux/sched/user.h b/include/linux/sched/user.h
index d33d867ad6c1..8a34446681aa 100644
--- a/include/linux/sched/user.h
+++ b/include/linux/sched/user.h
@@ -18,10 +18,6 @@ struct user_struct {
#endif
#ifdef CONFIG_EPOLL
atomic_long_t epoll_watches; /* The number of file descriptors currently watched */
-#endif
-#ifdef CONFIG_POSIX_MQUEUE
- /* protected by mq_lock */
- unsigned long mq_bytes; /* How many bytes can be allocated to mqueue? */
#endif
unsigned long locked_shm; /* How many pages of mlocked shm ? */
unsigned long unix_inflight; /* How many files in flight in unix sockets */
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index bca7ba20f552..66d471753bed 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -51,6 +51,7 @@ enum ucount_type {
UCOUNT_INOTIFY_WATCHES,
#endif
UCOUNT_RLIMIT_NPROC,
+ UCOUNT_RLIMIT_MSGQUEUE,
UCOUNT_COUNTS,
};
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index beff0cfcd1e8..05fcf067131f 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -144,7 +144,7 @@ struct mqueue_inode_info {
struct pid *notify_owner;
u32 notify_self_exec_id;
struct user_namespace *notify_user_ns;
- struct user_struct *user; /* user who created, for accounting */
+ struct ucounts *ucounts; /* user who created, for accounting */
struct sock *notify_sock;
struct sk_buff *notify_cookie;
@@ -292,7 +292,6 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
struct ipc_namespace *ipc_ns, umode_t mode,
struct mq_attr *attr)
{
- struct user_struct *u = current_user();
struct inode *inode;
int ret = -ENOMEM;
@@ -309,6 +308,8 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
if (S_ISREG(mode)) {
struct mqueue_inode_info *info;
unsigned long mq_bytes, mq_treesize;
+ struct ucounts *ucounts;
+ bool overlimit;
inode->i_fop = &mqueue_file_operations;
inode->i_size = FILENT_SIZE;
@@ -321,7 +322,7 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
info->notify_owner = NULL;
info->notify_user_ns = NULL;
info->qsize = 0;
- info->user = NULL; /* set when all is ok */
+ info->ucounts = NULL; /* set when all is ok */
info->msg_tree = RB_ROOT;
info->msg_tree_rightmost = NULL;
info->node_cache = NULL;
@@ -371,19 +372,19 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
if (mq_bytes + mq_treesize < mq_bytes)
goto out_inode;
mq_bytes += mq_treesize;
+ ucounts = current_ucounts();
spin_lock(&mq_lock);
- if (u->mq_bytes + mq_bytes < u->mq_bytes ||
- u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
+ overlimit = inc_rlimit_ucounts_and_test(ucounts, UCOUNT_RLIMIT_MSGQUEUE,
+ mq_bytes, rlimit(RLIMIT_MSGQUEUE));
+ if (overlimit) {
+ dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MSGQUEUE, mq_bytes);
spin_unlock(&mq_lock);
/* mqueue_evict_inode() releases info->messages */
ret = -EMFILE;
goto out_inode;
}
- u->mq_bytes += mq_bytes;
spin_unlock(&mq_lock);
-
- /* all is ok */
- info->user = get_uid(u);
+ info->ucounts = get_ucounts(ucounts);
} else if (S_ISDIR(mode)) {
inc_nlink(inode);
/* Some things misbehave if size == 0 on a directory */
@@ -497,7 +498,7 @@ static void mqueue_free_inode(struct inode *inode)
static void mqueue_evict_inode(struct inode *inode)
{
struct mqueue_inode_info *info;
- struct user_struct *user;
+ struct ucounts *ucounts;
struct ipc_namespace *ipc_ns;
struct msg_msg *msg, *nmsg;
LIST_HEAD(tmp_msg);
@@ -520,8 +521,8 @@ static void mqueue_evict_inode(struct inode *inode)
free_msg(msg);
}
- user = info->user;
- if (user) {
+ ucounts = info->ucounts;
+ if (ucounts) {
unsigned long mq_bytes, mq_treesize;
/* Total amount of bytes accounted for the mqueue */
@@ -533,7 +534,7 @@ static void mqueue_evict_inode(struct inode *inode)
info->attr.mq_msgsize);
spin_lock(&mq_lock);
- user->mq_bytes -= mq_bytes;
+ dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MSGQUEUE, mq_bytes);
/*
* get_ns_from_inode() ensures that the
* (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
@@ -543,7 +544,7 @@ static void mqueue_evict_inode(struct inode *inode)
if (ipc_ns)
ipc_ns->mq_queues_count--;
spin_unlock(&mq_lock);
- free_uid(user);
+ put_ucounts(ucounts);
}
if (ipc_ns)
put_ipc_ns(ipc_ns);
diff --git a/kernel/fork.c b/kernel/fork.c
index d50a720adbf1..bdd5be6062ab 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -824,6 +824,7 @@ void __init fork_init(void)
}
init_user_ns.ucount_max[UCOUNT_RLIMIT_NPROC] = task_rlimit(&init_task, RLIMIT_NPROC);
+ init_user_ns.ucount_max[UCOUNT_RLIMIT_MSGQUEUE] = task_rlimit(&init_task, RLIMIT_MSGQUEUE);
#ifdef CONFIG_VMAP_STACK
cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
diff --git a/kernel/ucount.c b/kernel/ucount.c
index 8f5bc29ac453..4e690e085f7d 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -75,6 +75,7 @@ static struct ctl_table user_table[] = {
UCOUNT_ENTRY("max_inotify_instances"),
UCOUNT_ENTRY("max_inotify_watches"),
#endif
+ { },
{ },
{ }
};
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 2434b13b02e5..cc90d5203acf 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -122,6 +122,7 @@ int create_user_ns(struct cred *new)
ns->ucount_max[i] = INT_MAX;
}
ns->ucount_max[UCOUNT_RLIMIT_NPROC] = rlimit(RLIMIT_NPROC);
+ ns->ucount_max[UCOUNT_RLIMIT_MSGQUEUE] = rlimit(RLIMIT_MSGQUEUE);
ns->ucounts = ucounts;
/* Inherit USERNS_SETGROUPS_ALLOWED from our parent */
--
2.29.2
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH v5 5/7] Reimplement RLIMIT_SIGPENDING on top of ucounts
2021-02-01 14:18 [PATCH v5 0/7] Count rlimits in each user namespace Alexey Gladkov
` (3 preceding siblings ...)
2021-02-01 14:18 ` [PATCH v5 4/7] Reimplement RLIMIT_MSGQUEUE " Alexey Gladkov
@ 2021-02-01 14:18 ` Alexey Gladkov
2021-02-01 14:18 ` [PATCH v5 6/7] Reimplement RLIMIT_MEMLOCK " Alexey Gladkov
2021-02-01 14:18 ` [PATCH v5 7/7] kselftests: Add test to check for rlimit changes in different user namespaces Alexey Gladkov
6 siblings, 0 replies; 8+ messages in thread
From: Alexey Gladkov @ 2021-02-01 14:18 UTC (permalink / raw)
To: LKML, io-uring, Kernel Hardening, Linux Containers, linux-mm
Cc: Alexey Gladkov, Andrew Morton, Christian Brauner,
Eric W . Biederman, Jann Horn, Jens Axboe, Kees Cook,
Linus Torvalds, Oleg Nesterov
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.
Signed-off-by: Alexey Gladkov <[email protected]>
---
fs/proc/array.c | 2 +-
include/linux/sched/user.h | 1 -
include/linux/signal_types.h | 4 ++-
include/linux/user_namespace.h | 1 +
kernel/fork.c | 1 +
kernel/signal.c | 53 ++++++++++++++--------------------
kernel/ucount.c | 1 +
kernel/user.c | 1 -
kernel/user_namespace.c | 1 +
9 files changed, 30 insertions(+), 35 deletions(-)
diff --git a/fs/proc/array.c b/fs/proc/array.c
index bb87e4d89cd8..74b0ea4b7e38 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -284,7 +284,7 @@ static inline void task_sig(struct seq_file *m, struct task_struct *p)
collect_sigign_sigcatch(p, &ignored, &caught);
num_threads = get_nr_threads(p);
rcu_read_lock(); /* FIXME: is this correct? */
- qsize = atomic_read(&__task_cred(p)->user->sigpending);
+ qsize = get_ucounts_value(task_ucounts(p), UCOUNT_RLIMIT_SIGPENDING);
rcu_read_unlock();
qlim = task_rlimit(p, RLIMIT_SIGPENDING);
unlock_task_sighand(p, &flags);
diff --git a/include/linux/sched/user.h b/include/linux/sched/user.h
index 8a34446681aa..8ba9cec4fb99 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 sigpending; /* How many pending signals does this user have? */
#ifdef CONFIG_FANOTIFY
atomic_t fanotify_listeners;
#endif
diff --git a/include/linux/signal_types.h b/include/linux/signal_types.h
index 68e06c75c5b2..34cb28b8f16c 100644
--- a/include/linux/signal_types.h
+++ b/include/linux/signal_types.h
@@ -13,6 +13,8 @@ typedef struct kernel_siginfo {
__SIGINFO;
} kernel_siginfo_t;
+struct ucounts;
+
/*
* Real Time signals may be queued.
*/
@@ -21,7 +23,7 @@ struct sigqueue {
struct list_head list;
int flags;
kernel_siginfo_t info;
- struct user_struct *user;
+ struct ucounts *ucounts;
};
/* flags values. */
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 66d471753bed..66aebabc6c7f 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -52,6 +52,7 @@ enum ucount_type {
#endif
UCOUNT_RLIMIT_NPROC,
UCOUNT_RLIMIT_MSGQUEUE,
+ UCOUNT_RLIMIT_SIGPENDING,
UCOUNT_COUNTS,
};
diff --git a/kernel/fork.c b/kernel/fork.c
index bdd5be6062ab..4c91709af704 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -825,6 +825,7 @@ void __init fork_init(void)
init_user_ns.ucount_max[UCOUNT_RLIMIT_NPROC] = task_rlimit(&init_task, RLIMIT_NPROC);
init_user_ns.ucount_max[UCOUNT_RLIMIT_MSGQUEUE] = task_rlimit(&init_task, RLIMIT_MSGQUEUE);
+ init_user_ns.ucount_max[UCOUNT_RLIMIT_SIGPENDING] = task_rlimit(&init_task, RLIMIT_SIGPENDING);
#ifdef CONFIG_VMAP_STACK
cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
diff --git a/kernel/signal.c b/kernel/signal.c
index 5736c55aaa1a..b01c2007a282 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -412,49 +412,40 @@ void task_join_group_stop(struct task_struct *task)
static struct sigqueue *
__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
{
- struct sigqueue *q = NULL;
- struct user_struct *user;
- int sigpending;
+ struct sigqueue *q = kmem_cache_alloc(sigqueue_cachep, flags);
- /*
- * Protect access to @t credentials. This can go away when all
- * callers hold rcu read lock.
- *
- * NOTE! A pending signal will hold on to the user refcount,
- * and we get/put the refcount only when the sigpending count
- * changes from/to zero.
- */
- rcu_read_lock();
- user = __task_cred(t)->user;
- sigpending = atomic_inc_return(&user->sigpending);
- if (sigpending == 1)
- get_uid(user);
- rcu_read_unlock();
+ if (likely(q != NULL)) {
+ bool overlimit;
- if (override_rlimit || likely(sigpending <= task_rlimit(t, RLIMIT_SIGPENDING))) {
- q = kmem_cache_alloc(sigqueue_cachep, flags);
- } else {
- print_dropped_signal(sig);
- }
-
- if (unlikely(q == NULL)) {
- if (atomic_dec_and_test(&user->sigpending))
- free_uid(user);
- } else {
INIT_LIST_HEAD(&q->list);
q->flags = 0;
- q->user = user;
+
+ /*
+ * Protect access to @t credentials. This can go away when all
+ * callers hold rcu read lock.
+ */
+ rcu_read_lock();
+ q->ucounts = get_ucounts(task_ucounts(t));
+ overlimit = inc_rlimit_ucounts_and_test(q->ucounts, UCOUNT_RLIMIT_SIGPENDING,
+ 1, task_rlimit(t, RLIMIT_SIGPENDING));
+
+ if (override_rlimit || likely(!overlimit)) {
+ rcu_read_unlock();
+ return q;
+ }
+ rcu_read_unlock();
}
- return q;
+ print_dropped_signal(sig);
+ return NULL;
}
static void __sigqueue_free(struct sigqueue *q)
{
if (q->flags & SIGQUEUE_PREALLOC)
return;
- if (atomic_dec_and_test(&q->user->sigpending))
- free_uid(q->user);
+ dec_rlimit_ucounts(q->ucounts, UCOUNT_RLIMIT_SIGPENDING, 1);
+ put_ucounts(q->ucounts);
kmem_cache_free(sigqueue_cachep, q);
}
diff --git a/kernel/ucount.c b/kernel/ucount.c
index 4e690e085f7d..83cf02fdeaaf 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -75,6 +75,7 @@ static struct ctl_table user_table[] = {
UCOUNT_ENTRY("max_inotify_instances"),
UCOUNT_ENTRY("max_inotify_watches"),
#endif
+ { },
{ },
{ },
{ }
diff --git a/kernel/user.c b/kernel/user.c
index 7f5ff498207a..6737327f83be 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),
- .sigpending = ATOMIC_INIT(0),
.locked_shm = 0,
.uid = GLOBAL_ROOT_UID,
.ratelimit = RATELIMIT_STATE_INIT(root_user.ratelimit, 0, 0),
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index cc90d5203acf..df1bed32dd48 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -123,6 +123,7 @@ int create_user_ns(struct cred *new)
}
ns->ucount_max[UCOUNT_RLIMIT_NPROC] = rlimit(RLIMIT_NPROC);
ns->ucount_max[UCOUNT_RLIMIT_MSGQUEUE] = rlimit(RLIMIT_MSGQUEUE);
+ ns->ucount_max[UCOUNT_RLIMIT_SIGPENDING] = rlimit(RLIMIT_SIGPENDING);
ns->ucounts = ucounts;
/* Inherit USERNS_SETGROUPS_ALLOWED from our parent */
--
2.29.2
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH v5 6/7] Reimplement RLIMIT_MEMLOCK on top of ucounts
2021-02-01 14:18 [PATCH v5 0/7] Count rlimits in each user namespace Alexey Gladkov
` (4 preceding siblings ...)
2021-02-01 14:18 ` [PATCH v5 5/7] Reimplement RLIMIT_SIGPENDING " Alexey Gladkov
@ 2021-02-01 14:18 ` Alexey Gladkov
2021-02-01 14:18 ` [PATCH v5 7/7] kselftests: Add test to check for rlimit changes in different user namespaces Alexey Gladkov
6 siblings, 0 replies; 8+ messages in thread
From: Alexey Gladkov @ 2021-02-01 14:18 UTC (permalink / raw)
To: LKML, io-uring, Kernel Hardening, Linux Containers, linux-mm
Cc: Alexey Gladkov, Andrew Morton, Christian Brauner,
Eric W . Biederman, Jann Horn, Jens Axboe, Kees Cook,
Linus Torvalds, Oleg Nesterov
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.
Signed-off-by: Alexey Gladkov <[email protected]>
---
fs/hugetlbfs/inode.c | 17 ++++++++---------
include/linux/hugetlb.h | 3 +--
include/linux/mm.h | 4 ++--
include/linux/sched/user.h | 1 -
include/linux/shmem_fs.h | 2 +-
include/linux/user_namespace.h | 1 +
ipc/shm.c | 31 ++++++++++++++++--------------
kernel/fork.c | 1 +
kernel/ucount.c | 1 +
kernel/user.c | 1 -
kernel/user_namespace.c | 1 +
mm/memfd.c | 4 +---
mm/mlock.c | 35 +++++++++++++---------------------
mm/mmap.c | 3 +--
mm/shmem.c | 8 ++++----
15 files changed, 52 insertions(+), 61 deletions(-)
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index b5c109703daa..82298412f020 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -1451,34 +1451,35 @@ static int get_hstate_idx(int page_size_log)
* otherwise hugetlb_reserve_pages reserves one less hugepages than intended.
*/
struct file *hugetlb_file_setup(const char *name, size_t size,
- vm_flags_t acctflag, struct user_struct **user,
+ vm_flags_t acctflag,
int creat_flags, int page_size_log)
{
struct inode *inode;
struct vfsmount *mnt;
int hstate_idx;
struct file *file;
+ const struct cred *cred;
hstate_idx = get_hstate_idx(page_size_log);
if (hstate_idx < 0)
return ERR_PTR(-ENODEV);
- *user = NULL;
mnt = hugetlbfs_vfsmount[hstate_idx];
if (!mnt)
return ERR_PTR(-ENOENT);
if (creat_flags == HUGETLB_SHMFS_INODE && !can_do_hugetlb_shm()) {
- *user = current_user();
- if (user_shm_lock(size, *user)) {
+ cred = current_cred();
+ if (user_shm_lock(size, cred)) {
task_lock(current);
pr_warn_once("%s (%d): Using mlock ulimits for SHM_HUGETLB is deprecated\n",
current->comm, current->pid);
task_unlock(current);
} else {
- *user = NULL;
return ERR_PTR(-EPERM);
}
+ } else {
+ cred = NULL;
}
file = ERR_PTR(-ENOSPC);
@@ -1503,10 +1504,8 @@ struct file *hugetlb_file_setup(const char *name, size_t size,
iput(inode);
out:
- if (*user) {
- user_shm_unlock(size, *user);
- *user = NULL;
- }
+ if (cred)
+ user_shm_unlock(size, cred);
return file;
}
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index ebca2ef02212..fbd36c452648 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -434,8 +434,7 @@ static inline struct hugetlbfs_inode_info *HUGETLBFS_I(struct inode *inode)
extern const struct file_operations hugetlbfs_file_operations;
extern const struct vm_operations_struct hugetlb_vm_ops;
struct file *hugetlb_file_setup(const char *name, size_t size, vm_flags_t acct,
- struct user_struct **user, int creat_flags,
- int page_size_log);
+ int creat_flags, int page_size_log);
static inline bool is_file_hugepages(struct file *file)
{
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ecdf8a8cd6ae..30a37aef1ab9 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1628,8 +1628,8 @@ extern bool can_do_mlock(void);
#else
static inline bool can_do_mlock(void) { return false; }
#endif
-extern int user_shm_lock(size_t, struct user_struct *);
-extern void user_shm_unlock(size_t, struct user_struct *);
+extern int user_shm_lock(size_t, const struct cred *);
+extern void user_shm_unlock(size_t, const struct cred *);
/*
* Parameter block passed down to zap_pte_range in exceptional cases.
diff --git a/include/linux/sched/user.h b/include/linux/sched/user.h
index 8ba9cec4fb99..82bd2532da6b 100644
--- a/include/linux/sched/user.h
+++ b/include/linux/sched/user.h
@@ -18,7 +18,6 @@ struct user_struct {
#ifdef CONFIG_EPOLL
atomic_long_t epoll_watches; /* The number of file descriptors currently watched */
#endif
- unsigned long locked_shm; /* How many pages of mlocked shm ? */
unsigned long unix_inflight; /* How many files in flight in unix sockets */
atomic_long_t pipe_bufs; /* how many pages are allocated in pipe buffers */
diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index d82b6f396588..10f50b1c4e0e 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -65,7 +65,7 @@ extern struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt,
extern int shmem_zero_setup(struct vm_area_struct *);
extern unsigned long shmem_get_unmapped_area(struct file *, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags);
-extern int shmem_lock(struct file *file, int lock, struct user_struct *user);
+extern int shmem_lock(struct file *file, int lock, const struct cred *cred);
#ifdef CONFIG_SHMEM
extern const struct address_space_operations shmem_aops;
static inline bool shmem_mapping(struct address_space *mapping)
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 66aebabc6c7f..359f67f7b972 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -53,6 +53,7 @@ enum ucount_type {
UCOUNT_RLIMIT_NPROC,
UCOUNT_RLIMIT_MSGQUEUE,
UCOUNT_RLIMIT_SIGPENDING,
+ UCOUNT_RLIMIT_MEMLOCK,
UCOUNT_COUNTS,
};
diff --git a/ipc/shm.c b/ipc/shm.c
index febd88daba8c..40c566cd6f7a 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -60,7 +60,7 @@ struct shmid_kernel /* private to the kernel */
time64_t shm_ctim;
struct pid *shm_cprid;
struct pid *shm_lprid;
- struct user_struct *mlock_user;
+ const struct cred *mlock_cred;
/* The task created the shm object. NULL if the task is dead. */
struct task_struct *shm_creator;
@@ -286,10 +286,10 @@ static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
shm_rmid(ns, shp);
shm_unlock(shp);
if (!is_file_hugepages(shm_file))
- shmem_lock(shm_file, 0, shp->mlock_user);
- else if (shp->mlock_user)
+ shmem_lock(shm_file, 0, shp->mlock_cred);
+ else if (shp->mlock_cred)
user_shm_unlock(i_size_read(file_inode(shm_file)),
- shp->mlock_user);
+ shp->mlock_cred);
fput(shm_file);
ipc_update_pid(&shp->shm_cprid, NULL);
ipc_update_pid(&shp->shm_lprid, NULL);
@@ -625,7 +625,7 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
shp->shm_perm.key = key;
shp->shm_perm.mode = (shmflg & S_IRWXUGO);
- shp->mlock_user = NULL;
+ shp->mlock_cred = NULL;
shp->shm_perm.security = NULL;
error = security_shm_alloc(&shp->shm_perm);
@@ -650,8 +650,9 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
if (shmflg & SHM_NORESERVE)
acctflag = VM_NORESERVE;
file = hugetlb_file_setup(name, hugesize, acctflag,
- &shp->mlock_user, HUGETLB_SHMFS_INODE,
+ HUGETLB_SHMFS_INODE,
(shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
+ shp->mlock_cred = current_cred();
} else {
/*
* Do not allow no accounting for OVERCOMMIT_NEVER, even
@@ -663,8 +664,10 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
file = shmem_kernel_file_setup(name, size, acctflag);
}
error = PTR_ERR(file);
- if (IS_ERR(file))
+ if (IS_ERR(file)) {
+ shp->mlock_cred = NULL;
goto no_file;
+ }
shp->shm_cprid = get_pid(task_tgid(current));
shp->shm_lprid = NULL;
@@ -698,8 +701,8 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
no_id:
ipc_update_pid(&shp->shm_cprid, NULL);
ipc_update_pid(&shp->shm_lprid, NULL);
- if (is_file_hugepages(file) && shp->mlock_user)
- user_shm_unlock(size, shp->mlock_user);
+ if (is_file_hugepages(file) && shp->mlock_cred)
+ user_shm_unlock(size, shp->mlock_cred);
fput(file);
ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
return error;
@@ -1105,12 +1108,12 @@ static int shmctl_do_lock(struct ipc_namespace *ns, int shmid, int cmd)
goto out_unlock0;
if (cmd == SHM_LOCK) {
- struct user_struct *user = current_user();
+ const struct cred *cred = current_cred();
- err = shmem_lock(shm_file, 1, user);
+ err = shmem_lock(shm_file, 1, cred);
if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
shp->shm_perm.mode |= SHM_LOCKED;
- shp->mlock_user = user;
+ shp->mlock_cred = cred;
}
goto out_unlock0;
}
@@ -1118,9 +1121,9 @@ static int shmctl_do_lock(struct ipc_namespace *ns, int shmid, int cmd)
/* SHM_UNLOCK */
if (!(shp->shm_perm.mode & SHM_LOCKED))
goto out_unlock0;
- shmem_lock(shm_file, 0, shp->mlock_user);
+ shmem_lock(shm_file, 0, shp->mlock_cred);
shp->shm_perm.mode &= ~SHM_LOCKED;
- shp->mlock_user = NULL;
+ shp->mlock_cred = NULL;
get_file(shm_file);
ipc_unlock_object(&shp->shm_perm);
rcu_read_unlock();
diff --git a/kernel/fork.c b/kernel/fork.c
index 4c91709af704..fc5de7d2a1e1 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -826,6 +826,7 @@ void __init fork_init(void)
init_user_ns.ucount_max[UCOUNT_RLIMIT_NPROC] = task_rlimit(&init_task, RLIMIT_NPROC);
init_user_ns.ucount_max[UCOUNT_RLIMIT_MSGQUEUE] = task_rlimit(&init_task, RLIMIT_MSGQUEUE);
init_user_ns.ucount_max[UCOUNT_RLIMIT_SIGPENDING] = task_rlimit(&init_task, RLIMIT_SIGPENDING);
+ init_user_ns.ucount_max[UCOUNT_RLIMIT_MEMLOCK] = task_rlimit(&init_task, RLIMIT_MEMLOCK);
#ifdef CONFIG_VMAP_STACK
cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
diff --git a/kernel/ucount.c b/kernel/ucount.c
index 83cf02fdeaaf..8abbe761ecfd 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -78,6 +78,7 @@ static struct ctl_table user_table[] = {
{ },
{ },
{ },
+ { },
{ }
};
#endif /* CONFIG_SYSCTL */
diff --git a/kernel/user.c b/kernel/user.c
index 6737327f83be..c82399c1618a 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),
- .locked_shm = 0,
.uid = GLOBAL_ROOT_UID,
.ratelimit = RATELIMIT_STATE_INIT(root_user.ratelimit, 0, 0),
};
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index df1bed32dd48..5ef0d4b182ba 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -124,6 +124,7 @@ int create_user_ns(struct cred *new)
ns->ucount_max[UCOUNT_RLIMIT_NPROC] = rlimit(RLIMIT_NPROC);
ns->ucount_max[UCOUNT_RLIMIT_MSGQUEUE] = rlimit(RLIMIT_MSGQUEUE);
ns->ucount_max[UCOUNT_RLIMIT_SIGPENDING] = rlimit(RLIMIT_SIGPENDING);
+ ns->ucount_max[UCOUNT_RLIMIT_MEMLOCK] = rlimit(RLIMIT_MEMLOCK);
ns->ucounts = ucounts;
/* Inherit USERNS_SETGROUPS_ALLOWED from our parent */
diff --git a/mm/memfd.c b/mm/memfd.c
index 2647c898990c..9f80f162791a 100644
--- a/mm/memfd.c
+++ b/mm/memfd.c
@@ -297,9 +297,7 @@ SYSCALL_DEFINE2(memfd_create,
}
if (flags & MFD_HUGETLB) {
- struct user_struct *user = NULL;
-
- file = hugetlb_file_setup(name, 0, VM_NORESERVE, &user,
+ file = hugetlb_file_setup(name, 0, VM_NORESERVE,
HUGETLB_ANONHUGE_INODE,
(flags >> MFD_HUGE_SHIFT) &
MFD_HUGE_MASK);
diff --git a/mm/mlock.c b/mm/mlock.c
index 55b3b3672977..2d49d1afd7e0 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -812,15 +812,10 @@ SYSCALL_DEFINE0(munlockall)
return ret;
}
-/*
- * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB
- * shm segments) get accounted against the user_struct instead.
- */
-static DEFINE_SPINLOCK(shmlock_user_lock);
-
-int user_shm_lock(size_t size, struct user_struct *user)
+int user_shm_lock(size_t size, const struct cred *cred)
{
unsigned long lock_limit, locked;
+ bool overlimit;
int allowed = 0;
locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
@@ -828,22 +823,18 @@ int user_shm_lock(size_t size, struct user_struct *user)
if (lock_limit == RLIM_INFINITY)
allowed = 1;
lock_limit >>= PAGE_SHIFT;
- spin_lock(&shmlock_user_lock);
- if (!allowed &&
- locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK))
- goto out;
- get_uid(user);
- user->locked_shm += locked;
- allowed = 1;
-out:
- spin_unlock(&shmlock_user_lock);
- return allowed;
+
+ overlimit = inc_rlimit_ucounts_and_test(cred->ucounts, UCOUNT_RLIMIT_MEMLOCK,
+ locked, lock_limit);
+
+ if (!allowed && overlimit && !capable(CAP_IPC_LOCK)) {
+ dec_rlimit_ucounts(cred->ucounts, UCOUNT_RLIMIT_MEMLOCK, locked);
+ return 0;
+ }
+ return 1;
}
-void user_shm_unlock(size_t size, struct user_struct *user)
+void user_shm_unlock(size_t size, const struct cred *cred)
{
- spin_lock(&shmlock_user_lock);
- user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
- spin_unlock(&shmlock_user_lock);
- free_uid(user);
+ dec_rlimit_ucounts(cred->ucounts, UCOUNT_RLIMIT_MEMLOCK, (size + PAGE_SIZE - 1) >> PAGE_SHIFT);
}
diff --git a/mm/mmap.c b/mm/mmap.c
index dc7206032387..e7980e2c18e8 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1607,7 +1607,6 @@ unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
goto out_fput;
}
} else if (flags & MAP_HUGETLB) {
- struct user_struct *user = NULL;
struct hstate *hs;
hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
@@ -1623,7 +1622,7 @@ unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
*/
file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
VM_NORESERVE,
- &user, HUGETLB_ANONHUGE_INODE,
+ HUGETLB_ANONHUGE_INODE,
(flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
if (IS_ERR(file))
return PTR_ERR(file);
diff --git a/mm/shmem.c b/mm/shmem.c
index 7c6b6d8f6c39..de9bf6866f51 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2225,7 +2225,7 @@ static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
}
#endif
-int shmem_lock(struct file *file, int lock, struct user_struct *user)
+int shmem_lock(struct file *file, int lock, const struct cred *cred)
{
struct inode *inode = file_inode(file);
struct shmem_inode_info *info = SHMEM_I(inode);
@@ -2237,13 +2237,13 @@ int shmem_lock(struct file *file, int lock, struct user_struct *user)
* no serialization needed when called from shm_destroy().
*/
if (lock && !(info->flags & VM_LOCKED)) {
- if (!user_shm_lock(inode->i_size, user))
+ if (!user_shm_lock(inode->i_size, cred))
goto out_nomem;
info->flags |= VM_LOCKED;
mapping_set_unevictable(file->f_mapping);
}
- if (!lock && (info->flags & VM_LOCKED) && user) {
- user_shm_unlock(inode->i_size, user);
+ if (!lock && (info->flags & VM_LOCKED) && cred) {
+ user_shm_unlock(inode->i_size, cred);
info->flags &= ~VM_LOCKED;
mapping_clear_unevictable(file->f_mapping);
}
--
2.29.2
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH v5 7/7] kselftests: Add test to check for rlimit changes in different user namespaces
2021-02-01 14:18 [PATCH v5 0/7] Count rlimits in each user namespace Alexey Gladkov
` (5 preceding siblings ...)
2021-02-01 14:18 ` [PATCH v5 6/7] Reimplement RLIMIT_MEMLOCK " Alexey Gladkov
@ 2021-02-01 14:18 ` Alexey Gladkov
6 siblings, 0 replies; 8+ messages in thread
From: Alexey Gladkov @ 2021-02-01 14:18 UTC (permalink / raw)
To: LKML, io-uring, Kernel Hardening, Linux Containers, linux-mm
Cc: Alexey Gladkov, Andrew Morton, Christian Brauner,
Eric W . Biederman, Jann Horn, Jens Axboe, Kees Cook,
Linus Torvalds, Oleg Nesterov
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 afbab4aeef3c..4dbeb5686f7b 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -46,6 +46,7 @@ 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);
+}
--
2.29.2
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