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Date: Mon, 2 Nov 2020 17:50:30 +0100
From: Alexey Gladkov <gladkov.alexey@...il.com>
To: LKML <linux-kernel@...r.kernel.org>,
Linux Containers <containers@...ts.linux-foundation.org>,
Kernel Hardening <kernel-hardening@...ts.openwall.com>
Cc: Alexey Gladkov <legion@...nel.org>,
"Eric W . Biederman" <ebiederm@...ssion.com>,
Kees Cook <keescook@...omium.org>,
Christian Brauner <christian@...uner.io>
Subject: [RFC PATCH v1 1/4] Increase size of ucounts to atomic_long_t
In order to be able to use ucounts for rlimits, the size must be increased.
For example user_struct.mq_bytes (RLIMIT_MSGQUEUE) is unsigned long.
Signed-off-by: Alexey Gladkov <gladkov.alexey@...il.com>
---
include/linux/user_namespace.h | 4 ++--
kernel/ucount.c | 14 +++++++-------
2 files changed, 9 insertions(+), 9 deletions(-)
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 6ef1c7109fc4..fc75af812d73 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -86,7 +86,7 @@ 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 {
@@ -94,7 +94,7 @@ 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..7b2bca8582ef 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;
@@ -199,14 +199,14 @@ struct ucounts *inc_ucount(struct user_namespace *ns, kuid_t uid,
int 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]);
+ int dec = atomic_long_dec_if_positive(&iter->ucount[type]);
WARN_ON_ONCE(dec < 0);
}
put_ucounts(ucounts);
--
2.25.4
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