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Reimplement RLIMIT_MEMLOCK on top of ucounts

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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>
This commit is contained in:
Alexey Gladkov
2021-04-22 14:27:14 +02:00
committed by Eric W. Biederman
parent d646969055
commit d7c9e99aee
15 changed files with 53 additions and 45 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
ipc/shm.c
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@@ -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;
struct ucounts *mlock_ucounts;
/* 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_ucounts);
else if (shp->mlock_ucounts)
user_shm_unlock(i_size_read(file_inode(shm_file)),
shp->mlock_user);
shp->mlock_ucounts);
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_ucounts = NULL;
shp->shm_perm.security = NULL;
error = security_shm_alloc(&shp->shm_perm);
@@ -650,7 +650,7 @@ 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,
&shp->mlock_ucounts, HUGETLB_SHMFS_INODE,
(shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
} else {
/*
@@ -698,8 +698,8 @@ 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_ucounts)
user_shm_unlock(size, shp->mlock_ucounts);
fput(file);
ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
return error;
@@ -1105,12 +1105,12 @@ 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();
struct ucounts *ucounts = current_ucounts();
err = shmem_lock(shm_file, 1, user);
err = shmem_lock(shm_file, 1, ucounts);
if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
shp->shm_perm.mode |= SHM_LOCKED;
shp->mlock_user = user;
shp->mlock_ucounts = ucounts;
}
goto out_unlock0;
}
@@ -1118,9 +1118,9 @@ 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_ucounts);
shp->shm_perm.mode &= ~SHM_LOCKED;
shp->mlock_user = NULL;
shp->mlock_ucounts = NULL;
get_file(shm_file);
ipc_unlock_object(&shp->shm_perm);
rcu_read_unlock();