From 6809864a2cc59332b246c183a2b78328f6aa551e Mon Sep 17 00:00:00 2001 From: Rom Lemarchand Date: Fri, 7 Nov 2014 12:48:17 -0800 Subject: [PATCH] cgroup: refactor allow_attach function into common code move cpu_cgroup_allow_attach to a common subsys_cgroup_allow_attach. This allows any process with CAP_SYS_NICE to move tasks across cgroups if they use this function as their allow_attach handler. Bug: 18260435 Change-Id: I6bb4933d07e889d0dc39e33b4e71320c34a2c90f Signed-off-by: Rom Lemarchand --- include/linux/cgroup.h | 16 ++++++++++++++++ kernel/cgroup.c | 19 +++++++++++++++++++ 2 files changed, 35 insertions(+) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index cb91b44f5f78..c08c83182e08 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -528,6 +528,17 @@ static inline void pr_cont_cgroup_path(struct cgroup *cgrp) pr_cont_kernfs_path(cgrp->kn); } +/* + * Default Android check for whether the current process is allowed to move a + * task across cgroups, either because CAP_SYS_NICE is set or because the uid + * of the calling process is the same as the moved task or because we are + * running as root. + * Returns 0 if this is allowed, or -EACCES otherwise. + */ +int subsys_cgroup_allow_attach(struct cgroup_subsys_state *css, + struct cgroup_taskset *tset); + + #else /* !CONFIG_CGROUPS */ struct cgroup_subsys_state; @@ -552,6 +563,11 @@ static inline void cgroup_free(struct task_struct *p) {} static inline int cgroup_init_early(void) { return 0; } static inline int cgroup_init(void) { return 0; } +static inline int subsys_cgroup_allow_attach(struct cgroup_subsys_state *css, + struct cgroup_taskset *tset) +{ + return 0; +} #endif /* !CONFIG_CGROUPS */ #endif /* _LINUX_CGROUP_H */ diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 470f6536b9e8..35591b841db2 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2663,6 +2663,25 @@ static int cgroup_attach_task(struct cgroup *dst_cgrp, return ret; } +int subsys_cgroup_allow_attach(struct cgroup_subsys_state *css, struct cgroup_taskset *tset) +{ + const struct cred *cred = current_cred(), *tcred; + struct task_struct *task; + + if (capable(CAP_SYS_NICE)) + return 0; + + cgroup_taskset_for_each(task, css, tset) { + tcred = __task_cred(task); + + if (current != task && !uid_eq(cred->euid, tcred->uid) && + !uid_eq(cred->euid, tcred->suid)) + return -EACCES; + } + + return 0; +} + static int cgroup_procs_write_permission(struct task_struct *task, struct cgroup *dst_cgrp, struct kernfs_open_file *of) -- 2.34.1