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authorAlexey Gladkov <legion@kernel.org>2021-04-22 15:27:14 +0300
committerEric W. Biederman <ebiederm@xmission.com>2021-04-30 22:14:02 +0300
commitd7c9e99aee48e6bc0b427f3e3c658a6aba15001e (patch)
tree61da3b62f597bf4d3658ce6d3198f7e4ae4ddf37 /mm/mlock.c
parentd64696905554e919321e31afc210606653b8f6a4 (diff)
downloadlinux-d7c9e99aee48e6bc0b427f3e3c658a6aba15001e.tar.xz
Reimplement RLIMIT_MEMLOCK on top of ucounts
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. Changelog v11: * Fix issue found by lkp robot. v8: * Fix issues found by lkp-tests project. v7: * Keep only ucounts for RLIMIT_MEMLOCK checks instead of struct cred. v6: * Fix bug in hugetlb_file_setup() detected by trinity. Reported-by: kernel test robot <oliver.sang@intel.com> Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Alexey Gladkov <legion@kernel.org> Link: https://lkml.kernel.org/r/970d50c70c71bfd4496e0e8d2a0a32feebebb350.1619094428.git.legion@kernel.org Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'mm/mlock.c')
-rw-r--r--mm/mlock.c22
1 files changed, 14 insertions, 8 deletions
diff --git a/mm/mlock.c b/mm/mlock.c
index f8f8cc32d03d..dd411aabf695 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -817,9 +817,10 @@ SYSCALL_DEFINE0(munlockall)
*/
static DEFINE_SPINLOCK(shmlock_user_lock);
-int user_shm_lock(size_t size, struct user_struct *user)
+int user_shm_lock(size_t size, struct ucounts *ucounts)
{
unsigned long lock_limit, locked;
+ long memlock;
int allowed = 0;
locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
@@ -828,21 +829,26 @@ int user_shm_lock(size_t size, struct user_struct *user)
allowed = 1;
lock_limit >>= PAGE_SHIFT;
spin_lock(&shmlock_user_lock);
- if (!allowed &&
- locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK))
+ memlock = inc_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked);
+
+ if (!allowed && (memlock == LONG_MAX || memlock > lock_limit) && !capable(CAP_IPC_LOCK)) {
+ dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked);
+ goto out;
+ }
+ if (!get_ucounts(ucounts)) {
+ dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked);
goto out;
- get_uid(user);
- user->locked_shm += locked;
+ }
allowed = 1;
out:
spin_unlock(&shmlock_user_lock);
return allowed;
}
-void user_shm_unlock(size_t size, struct user_struct *user)
+void user_shm_unlock(size_t size, struct ucounts *ucounts)
{
spin_lock(&shmlock_user_lock);
- user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, (size + PAGE_SIZE - 1) >> PAGE_SHIFT);
spin_unlock(&shmlock_user_lock);
- free_uid(user);
+ put_ucounts(ucounts);
}