diff options
| -rw-r--r-- | Documentation/cgroups/cgroups.txt | 3 | ||||
| -rw-r--r-- | Documentation/cgroups/devices.txt | 70 | ||||
| -rw-r--r-- | arch/powerpc/mm/numa.c | 1 | ||||
| -rw-r--r-- | block/blk-cgroup.h | 2 | ||||
| -rw-r--r-- | include/linux/cgroup.h | 170 | ||||
| -rw-r--r-- | include/linux/cpuset.h | 1 | ||||
| -rw-r--r-- | include/linux/res_counter.h | 2 | ||||
| -rw-r--r-- | kernel/cgroup.c | 724 | ||||
| -rw-r--r-- | kernel/cpuset.c | 115 | ||||
| -rw-r--r-- | kernel/events/core.c | 24 | ||||
| -rw-r--r-- | mm/memcontrol.c | 80 | ||||
| -rw-r--r-- | security/device_cgroup.c | 267 |
12 files changed, 826 insertions, 633 deletions
diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt index bcf1a00..638bf17 100644 --- a/Documentation/cgroups/cgroups.txt +++ b/Documentation/cgroups/cgroups.txt @@ -442,7 +442,7 @@ You can attach the current shell task by echoing 0: You can use the cgroup.procs file instead of the tasks file to move all threads in a threadgroup at once. Echoing the PID of any task in a threadgroup to cgroup.procs causes all tasks in that threadgroup to be -be attached to the cgroup. Writing 0 to cgroup.procs moves all tasks +attached to the cgroup. Writing 0 to cgroup.procs moves all tasks in the writing task's threadgroup. Note: Since every task is always a member of exactly one cgroup in each @@ -580,6 +580,7 @@ propagation along the hierarchy. See the comment on cgroup_for_each_descendant_pre() for details. void css_offline(struct cgroup *cgrp); +(cgroup_mutex held by caller) This is the counterpart of css_online() and called iff css_online() has succeeded on @cgrp. This signifies the beginning of the end of diff --git a/Documentation/cgroups/devices.txt b/Documentation/cgroups/devices.txt index 16624a7f8..3c1095c 100644 --- a/Documentation/cgroups/devices.txt +++ b/Documentation/cgroups/devices.txt @@ -13,9 +13,7 @@ either an integer or * for all. Access is a composition of r The root device cgroup starts with rwm to 'all'. A child device cgroup gets a copy of the parent. Administrators can then remove devices from the whitelist or add new entries. A child cgroup can -never receive a device access which is denied by its parent. However -when a device access is removed from a parent it will not also be -removed from the child(ren). +never receive a device access which is denied by its parent. 2. User Interface @@ -50,3 +48,69 @@ task to a new cgroup. (Again we'll probably want to change that). A cgroup may not be granted more permissions than the cgroup's parent has. + +4. Hierarchy + +device cgroups maintain hierarchy by making sure a cgroup never has more +access permissions than its parent. Every time an entry is written to +a cgroup's devices.deny file, all its children will have that entry removed +from their whitelist and all the locally set whitelist entries will be +re-evaluated. In case one of the locally set whitelist entries would provide +more access than the cgroup's parent, it'll be removed from the whitelist. + +Example: + A + / \ + B + + group behavior exceptions + A allow "b 8:* rwm", "c 116:1 rw" + B deny "c 1:3 rwm", "c 116:2 rwm", "b 3:* rwm" + +If a device is denied in group A: + # echo "c 116:* r" > A/devices.deny +it'll propagate down and after revalidating B's entries, the whitelist entry +"c 116:2 rwm" will be removed: + + group whitelist entries denied devices + A all "b 8:* rwm", "c 116:* rw" + B "c 1:3 rwm", "b 3:* rwm" all the rest + +In case parent's exceptions change and local exceptions are not allowed +anymore, they'll be deleted. + +Notice that new whitelist entries will not be propagated: + A + / \ + B + + group whitelist entries denied devices + A "c 1:3 rwm", "c 1:5 r" all the rest + B "c 1:3 rwm", "c 1:5 r" all the rest + +when adding "c *:3 rwm": + # echo "c *:3 rwm" >A/devices.allow + +the result: + group whitelist entries denied devices + A "c *:3 rwm", "c 1:5 r" all the rest + B "c 1:3 rwm", "c 1:5 r" all the rest + +but now it'll be possible to add new entries to B: + # echo "c 2:3 rwm" >B/devices.allow + # echo "c 50:3 r" >B/devices.allow +or even + # echo "c *:3 rwm" >B/devices.allow + +Allowing or denying all by writing 'a' to devices.allow or devices.deny will +not be possible once the device cgroups has children. + +4.1 Hierarchy (internal implementation) + +device cgroups is implemented internally using a behavior (ALLOW, DENY) and a +list of exceptions. The internal state is controlled using the same user +interface to preserve compatibility with the previous whitelist-only +implementation. Removal or addition of exceptions that will reduce the access +to devices will be propagated down the hierarchy. +For every propagated exception, the effective rules will be re-evaluated based +on current parent's access rules. diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c index b8020dc..fa33c54 100644 --- a/arch/powerpc/mm/numa.c +++ b/arch/powerpc/mm/numa.c @@ -22,6 +22,7 @@ #include <linux/pfn.h> #include <linux/cpuset.h> #include <linux/node.h> +#include <linux/slab.h> #include <asm/sparsemem.h> #include <asm/prom.h> #include <asm/smp.h> diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h index f2b2929..4e595ee 100644 --- a/block/blk-cgroup.h +++ b/block/blk-cgroup.h @@ -247,9 +247,7 @@ static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen) { int ret; - rcu_read_lock(); ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen); - rcu_read_unlock(); if (ret) strncpy(buf, "<unavailable>", buflen); return ret; diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 470073b..d86e215 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -19,6 +19,7 @@ #include <linux/idr.h> #include <linux/workqueue.h> #include <linux/xattr.h> +#include <linux/fs.h> #ifdef CONFIG_CGROUPS @@ -30,10 +31,6 @@ struct css_id; extern int cgroup_init_early(void); extern int cgroup_init(void); -extern void cgroup_lock(void); -extern int cgroup_lock_is_held(void); -extern bool cgroup_lock_live_group(struct cgroup *cgrp); -extern void cgroup_unlock(void); extern void cgroup_fork(struct task_struct *p); extern void cgroup_post_fork(struct task_struct *p); extern void cgroup_exit(struct task_struct *p, int run_callbacks); @@ -44,14 +41,25 @@ extern void cgroup_unload_subsys(struct cgroup_subsys *ss); extern const struct file_operations proc_cgroup_operations; -/* Define the enumeration of all builtin cgroup subsystems */ +/* + * Define the enumeration of all cgroup subsystems. + * + * We define ids for builtin subsystems and then modular ones. + */ #define SUBSYS(_x) _x ## _subsys_id, -#define IS_SUBSYS_ENABLED(option) IS_ENABLED(option) enum cgroup_subsys_id { +#define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option) +#include <linux/cgroup_subsys.h> +#undef IS_SUBSYS_ENABLED + CGROUP_BUILTIN_SUBSYS_COUNT, + + __CGROUP_SUBSYS_TEMP_PLACEHOLDER = CGROUP_BUILTIN_SUBSYS_COUNT - 1, + +#define IS_SUBSYS_ENABLED(option) IS_MODULE(option) #include <linux/cgroup_subsys.h> +#undef IS_SUBSYS_ENABLED CGROUP_SUBSYS_COUNT, }; -#undef IS_SUBSYS_ENABLED #undef SUBSYS /* Per-subsystem/per-cgroup state maintained by the system. */ @@ -148,6 +156,13 @@ enum { * specified at mount time and thus is implemented here. */ CGRP_CPUSET_CLONE_CHILDREN, + /* see the comment above CGRP_ROOT_SANE_BEHAVIOR for details */ + CGRP_SANE_BEHAVIOR, +}; + +struct cgroup_name { + struct rcu_head rcu_head; + char name[]; }; struct cgroup { @@ -172,11 +187,23 @@ struct cgroup { struct cgroup *parent; /* my parent */ struct dentry *dentry; /* cgroup fs entry, RCU protected */ + /* + * This is a copy of dentry->d_name, and it's needed because + * we can't use dentry->d_name in cgroup_path(). + * + * You must acquire rcu_read_lock() to access cgrp->name, and + * the only place that can change it is rename(), which is + * protected by parent dir's i_mutex. + * + * Normally you should use cgroup_name() wrapper rather than + * access it directly. + */ + struct cgroup_name __rcu *name; + /* Private pointers for each registered subsystem */ struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; struct cgroupfs_root *root; - struct cgroup *top_cgroup; /* * List of cg_cgroup_links pointing at css_sets with @@ -213,6 +240,96 @@ struct cgroup { struct simple_xattrs xattrs; }; +#define MAX_CGROUP_ROOT_NAMELEN 64 + +/* cgroupfs_root->flags */ +enum { + /* + * Unfortunately, cgroup core and various controllers are riddled + * with idiosyncrasies and pointless options. The following flag, + * when set, will force sane behavior - some options are forced on, + * others are disallowed, and some controllers will change their + * hierarchical or other behaviors. + * + * The set of behaviors affected by this flag are still being + * determined and developed and the mount option for this flag is + * prefixed with __DEVEL__. The prefix will be dropped once we + * reach the point where all behaviors are compatible with the + * planned unified hierarchy, which will automatically turn on this + * flag. + * + * The followings are the behaviors currently affected this flag. + * + * - Mount options "noprefix" and "clone_children" are disallowed. + * Also, cgroupfs file cgroup.clone_children is not created. + * + * - When mounting an existing superblock, mount options should + * match. + * + * - Remount is disallowed. + * + * - memcg: use_hierarchy is on by default and the cgroup file for + * the flag is not created. + * + * The followings are planned changes. + * + * - release_agent will be disallowed once replacement notification + * mechanism is implemented. + */ + CGRP_ROOT_SANE_BEHAVIOR = (1 << 0), + + CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */ + CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */ +}; + +/* + * A cgroupfs_root represents the root of a cgroup hierarchy, and may be + * associated with a superblock to form an active hierarchy. This is + * internal to cgroup core. Don't access directly from controllers. + */ +struct cgroupfs_root { + struct super_block *sb; + + /* + * The bitmask of subsystems intended to be attached to this + * hierarchy + */ + unsigned long subsys_mask; + + /* Unique id for this hierarchy. */ + int hierarchy_id; + + /* The bitmask of subsystems currently attached to this hierarchy */ + unsigned long actual_subsys_mask; + + /* A list running through the attached subsystems */ + struct list_head subsys_list; + + /* The root cgroup for this hierarchy */ + struct cgroup top_cgroup; + + /* Tracks how many cgroups are currently defined in hierarchy.*/ + int number_of_cgroups; + + /* A list running through the active hierarchies */ + struct list_head root_list; + + /* All cgroups on this root, cgroup_mutex protected */ + struct list_head allcg_list; + + /* Hierarchy-specific flags */ + unsigned long flags; + + /* IDs for cgroups in this hierarchy */ + struct ida cgroup_ida; + + /* The path to use for release notifications. */ + char release_agent_path[PATH_MAX]; + + /* The name for this hierarchy - may be empty */ + char name[MAX_CGROUP_ROOT_NAMELEN]; +}; + /* * A css_set is a structure holding pointers to a set of * cgroup_subsys_state objects. This saves space in the task struct @@ -278,6 +395,7 @@ struct cgroup_map_cb { /* cftype->flags */ #define CFTYPE_ONLY_ON_ROOT (1U << 0) /* only create on root cg */ #define CFTYPE_NOT_ON_ROOT (1U << 1) /* don't create on root cg */ +#define CFTYPE_INSANE (1U << 2) /* don't create if sane_behavior */ #define MAX_CFTYPE_NAME 64 @@ -304,9 +422,6 @@ struct cftype { /* CFTYPE_* flags */ unsigned int flags; - /* file xattrs */ - struct simple_xattrs xattrs; - int (*open)(struct inode *inode, struct file *file); ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft, struct file *file, @@ -404,18 +519,31 @@ struct cgroup_scanner { void *data; }; +/* + * See the comment above CGRP_ROOT_SANE_BEHAVIOR for details. This + * function can be called as long as @cgrp is accessible. + */ +static inline bool cgroup_sane_behavior(const struct cgroup *cgrp) +{ + return cgrp->root->flags & CGRP_ROOT_SANE_BEHAVIOR; +} + +/* Caller should hold rcu_read_lock() */ +static inline const char *cgroup_name(const struct cgroup *cgrp) +{ + return rcu_dereference(cgrp->name)->name; +} + int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts); int cgroup_rm_cftypes(struct cgroup_subsys *ss, struct cftype *cfts); int cgroup_is_removed(const struct cgroup *cgrp); +bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor); int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen); int cgroup_task_count(const struct cgroup *cgrp); -/* Return true if cgrp is a descendant of the task's cgroup */ -int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task); - /* * Control Group taskset, used to pass around set of tasks to cgroup_subsys * methods. @@ -523,10 +651,16 @@ static inline struct cgroup_subsys_state *cgroup_subsys_state( * rcu_dereference_check() conditions, such as locks used during the * cgroup_subsys::attach() methods. */ +#ifdef CONFIG_PROVE_RCU +extern struct mutex cgroup_mutex; +#define task_subsys_state_check(task, subsys_id, __c) \ + rcu_dereference_check((task)->cgroups->subsys[(subsys_id)], \ + lockdep_is_held(&(task)->alloc_lock) || \ + lockdep_is_held(&cgroup_mutex) || (__c)) +#else #define task_subsys_state_check(task, subsys_id, __c) \ - rcu_dereference_check(task->cgroups->subsys[subsys_id], \ - lockdep_is_held(&task->alloc_lock) || \ - cgroup_lock_is_held() || (__c)) + rcu_dereference((task)->cgroups->subsys[(subsys_id)]) +#endif static inline struct cgroup_subsys_state * task_subsys_state(struct task_struct *task, int subsys_id) @@ -661,8 +795,8 @@ struct task_struct *cgroup_iter_next(struct cgroup *cgrp, struct cgroup_iter *it); void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it); int cgroup_scan_tasks(struct cgroup_scanner *scan); -int cgroup_attach_task(struct cgroup *, struct task_struct *); int cgroup_attach_task_all(struct task_struct *from, struct task_struct *); +int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from); /* * CSS ID is ID for cgroup_subsys_state structs under subsys. This only works diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h index 8c8a60d..ccd1de8 100644 --- a/include/linux/cpuset.h +++ b/include/linux/cpuset.h @@ -11,7 +11,6 @@ #include <linux/sched.h> #include <linux/cpumask.h> #include <linux/nodemask.h> -#include <linux/cgroup.h> #include <linux/mm.h> #ifdef CONFIG_CPUSETS diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h index c230994..96a509b 100644 --- a/include/linux/res_counter.h +++ b/include/linux/res_counter.h @@ -13,7 +13,7 @@ * info about what this counter is. */ -#include <linux/cgroup.h> +#include <linux/spinlock.h> #include <linux/errno.h> /* diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 1f628bc..eeb7e49 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -30,7 +30,6 @@ #include <linux/cred.h> #include <linux/ctype.h> #include <linux/errno.h> -#include <linux/fs.h> #include <linux/init_task.h> #include <linux/kernel.h> #include <linux/list.h> @@ -59,7 +58,7 @@ #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ #include <linux/eventfd.h> #include <linux/poll.h> -#include <linux/flex_array.h> /* used in cgroup_attach_proc */ +#include <linux/flex_array.h> /* used in cgroup_attach_task */ #include <linux/kthread.h> #include <linux/atomic.h> @@ -83,7 +82,13 @@ * B happens only through cgroup_show_options() and using cgroup_root_mutex * breaks it. */ +#ifdef CONFIG_PROVE_RCU +DEFINE_MUTEX(cgroup_mutex); +EXPORT_SYMBOL_GPL(cgroup_mutex); /* only for task_subsys_state_check() */ +#else static DEFINE_MUTEX(cgroup_mutex); +#endif + static DEFINE_MUTEX(cgroup_root_mutex); /* @@ -98,56 +103,6 @@ static struct cgroup_subsys *subsys[CGROUP_SUBSYS_COUNT] = { #include <linux/cgroup_subsys.h> }; -#define MAX_CGROUP_ROOT_NAMELEN 64 - -/* - * A cgroupfs_root represents the root of a cgroup hierarchy, - * and may be associated with a superblock to form an active - * hierarchy - */ -struct cgroupfs_root { - struct super_block *sb; - - /* - * The bitmask of subsystems intended to be attached to this - * hierarchy - */ - unsigned long subsys_mask; - - /* Unique id for this hierarchy. */ - int hierarchy_id; - - /* The bitmask of subsystems currently attached to this hierarchy */ - unsigned long actual_subsys_mask; - - /* A list running through the attached subsystems */ - struct list_head subsys_list; - - /* The root cgroup for this hierarchy */ - struct cgroup top_cgroup; - - /* Tracks how many cgroups are currently defined in hierarchy.*/ - int number_of_cgroups; - - /* A list running through the active hierarchies */ - struct list_head root_list; - - /* All cgroups on this root, cgroup_mutex protected */ - struct list_head allcg_list; - - /* Hierarchy-specific flags */ - unsigned long flags; - - /* IDs for cgroups in this hierarchy */ - struct ida cgroup_ida; - - /* The path to use for release notifications. */ - char release_agent_path[PATH_MAX]; - - /* The name for this hierarchy - may be empty */ - char name[MAX_CGROUP_ROOT_NAMELEN]; -}; - /* * The "rootnode" hierarchy is the "dummy hierarchy", reserved for the * subsystems that are otherwise unattached - it never has more than a @@ -162,6 +117,9 @@ struct cfent { struct list_head node; struct dentry *dentry; struct cftype *type; + + /* file xattrs */ + struct simple_xattrs xattrs; }; /* @@ -238,6 +196,8 @@ static DEFINE_SPINLOCK(hierarchy_id_lock); /* dummytop is a shorthand for the dummy hierarchy's top cgroup */ #define dummytop (&rootnode.top_cgroup) +static struct cgroup_name root_cgroup_name = { .name = "/" }; + /* This flag indicates whether tasks in the fork and exit paths should * check for fork/exit handlers to call. This avoids us having to do * extra work in the fork/exit path if none of the subsystems need to @@ -249,20 +209,6 @@ static int cgroup_destroy_locked(struct cgroup *cgrp); static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys, struct cftype cfts[], bool is_add); -#ifdef CONFIG_PROVE_LOCKING -int cgroup_lock_is_held(void) -{ - return lockdep_is_held(&cgroup_mutex); -} -#else /* #ifdef CONFIG_PROVE_LOCKING */ -int cgroup_lock_is_held(void) -{ - return mutex_is_locked(&cgroup_mutex); -} -#endif /* #else #ifdef CONFIG_PROVE_LOCKING */ - -EXPORT_SYMBOL_GPL(cgroup_lock_is_held); - static int css_unbias_refcnt(int refcnt) { return refcnt >= 0 ? refcnt : refcnt - CSS_DEACT_BIAS; @@ -282,11 +228,25 @@ inline int cgroup_is_removed(const struct cgroup *cgrp) return test_bit(CGRP_REMOVED, &cgrp->flags); } -/* bits in struct cgroupfs_root flags field */ -enum { - ROOT_NOPREFIX, /* mounted subsystems have no named prefix */ - ROOT_XATTR, /* supports extended attributes */ -}; +/** + * cgroup_is_descendant - test ancestry + * @cgrp: the cgroup to be tested + * @ancestor: possible ancestor of @cgrp + * + * Test whether @cgrp is a descendant of @ancestor. It also returns %true + * if @cgrp == @ancestor. This function is safe to call as long as @cgrp + * and @ancestor are accessible. + */ +bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor) +{ + while (cgrp) { + if (cgrp == ancestor) + return true; + cgrp = cgrp->parent; + } + return false; +} +EXPORT_SYMBOL_GPL(cgroup_is_descendant); static int cgroup_is_releasable(const struct cgroup *cgrp) { @@ -327,6 +287,23 @@ static inline struct cftype *__d_cft(struct dentry *dentry) return __d_cfe(dentry)->type; } +/** + * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive. + * @cgrp: the cgroup to be checked for liveness + * + * On success, returns true; the mutex should be later unlocked. On + * failure returns false with no lock held. + */ +static bool cgroup_lock_live_group(struct cgroup *cgrp) +{ + mutex_lock(&cgroup_mutex); + if (cgroup_is_removed(cgrp)) { + mutex_unlock(&cgroup_mutex); + return false; + } + return true; +} + /* the list of cgroups eligible for automatic release. Protected by * release_list_lock */ static LIST_HEAD(release_list); @@ -800,27 +777,6 @@ static struct cgroup *task_cgroup_from_root(struct task_struct *task, * update of a tasks cgroup pointer by cgroup_attach_task() */ -/** - * cgroup_lock - lock out any changes to cgroup structures - * - */ -void cgroup_lock(void) -{ - mutex_lock(&cgroup_mutex); -} -EXPORT_SYMBOL_GPL(cgroup_lock); - -/** - * cgroup_unlock - release lock on cgroup changes - * - * Undo the lock taken in a previous cgroup_lock() call. - */ -void cgroup_unlock(void) -{ - mutex_unlock(&cgroup_mutex); -} -EXPORT_SYMBOL_GPL(cgroup_unlock); - /* * A couple of forward declarations required, due to cyclic reference loop: * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir -> @@ -859,6 +815,17 @@ static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb) return inode; } +static struct cgroup_name *cgroup_alloc_name(struct dentry *dentry) +{ + struct cgroup_name *name; + + name = kmalloc(sizeof(*name) + dentry->d_name.len + 1, GFP_KERNEL); + if (!name) + return NULL; + strcpy(name->name, dentry->d_name.name); + return name; +} + static void cgroup_free_fn(struct work_struct *work) { struct cgroup *cgrp = container_of(work, struct cgroup, free_work); @@ -875,8 +842,18 @@ static void cgroup_free_fn(struct work_struct *work) mutex_unlock(&cgroup_mutex); /* + * We get a ref to the parent's dentry, and put the ref when + * this cgroup is being freed, so it's guaranteed that the + * parent won't be destroyed before its children. + */ + dput(cgrp->parent->dentry); + + ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id); + + /* * Drop the active superblock reference that we took when we - * created the cgroup + * created the cgroup. This will free cgrp->root, if we are + * holding the last reference to @sb. */ deactivate_super(cgrp->root->sb); @@ -888,7 +865,7 @@ static void cgroup_free_fn(struct work_struct *work) simple_xattrs_free(&cgrp->xattrs); - ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id); + kfree(rcu_dereference_raw(cgrp->name)); kfree(cgrp); } @@ -910,13 +887,12 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode) } else { struct cfent *cfe = __d_cfe(dentry); struct cgroup *cgrp = dentry->d_parent->d_fsdata; - struct cftype *cft = cfe->type; WARN_ONCE(!list_empty(&cfe->node) && cgrp != &cgrp->root->top_cgroup, "cfe still linked for %s\n", cfe->type->name); + simple_xattrs_free(&cfe->xattrs); kfree(cfe); - simple_xattrs_free(&cft->xattrs); } iput(inode); } @@ -1108,9 +1084,11 @@ static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry) mutex_lock(&cgroup_root_mutex); for_each_subsys(root, ss) seq_printf(seq, ",%s", ss->name); - if (test_bit(ROOT_NOPREFIX, &root->flags)) + if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) + seq_puts(seq, ",sane_behavior"); + if (root->flags & CGRP_ROOT_NOPREFIX) seq_puts(seq, ",noprefix"); - if (test_bit(ROOT_XATTR, &root->flags)) + if (root->flags & CGRP_ROOT_XATTR) seq_puts(seq, ",xattr"); if (strlen(root->release_agent_path)) seq_printf(seq, ",release_agent=%s", root->release_agent_path); @@ -1172,8 +1150,12 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) all_ss = true; continue; } + if (!strcmp(token, "__DEVEL__sane_behavior")) { + opts->flags |= CGRP_ROOT_SANE_BEHAVIOR; + continue; + } if (!strcmp(token, "noprefix")) { - set_bit(ROOT_NOPREFIX, &opts->flags); + opts->flags |= CGRP_ROOT_NOPREFIX; continue; } if (!strcmp(token, "clone_children")) { @@ -1181,7 +1163,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) continue; } if (!strcmp(token, "xattr")) { - set_bit(ROOT_XATTR, &opts->flags); + opts->flags |= CGRP_ROOT_XATTR; continue; } if (!strncmp(token, "release_agent=", 14)) { @@ -1259,13 +1241,26 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) /* Consistency checks */ + if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) { + pr_warning("cgroup: sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n"); + + if (opts->flags & CGRP_ROOT_NOPREFIX) { + pr_err("cgroup: sane_behavior: noprefix is not allowed\n"); + return -EINVAL; + } + + if (opts->cpuset_clone_children) { + pr_err("cgroup: sane_behavior: clone_children is not allowed\n"); + return -EINVAL; + } + } + /* * Option noprefix was introduced just for backward compatibility * with the old cpuset, so we allow noprefix only if mounting just * the cpuset subsystem. */ - if (test_bit(ROOT_NOPREFIX, &opts->flags) && - (opts->subsys_mask & mask)) + if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask)) return -EINVAL; @@ -1336,6 +1331,11 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data) struct cgroup_sb_opts opts; unsigned long added_mask, removed_mask; + if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) { + pr_err("cgroup: sane_behavior: remount is not allowed\n"); + return -EINVAL; + } + mutex_lock(&cgrp->dentry->d_inode->i_mutex); mutex_lock(&cgroup_mutex); mutex_lock(&cgroup_root_mutex); @@ -1421,7 +1421,7 @@ static void init_cgroup_root(struct cgroupfs_root *root) INIT_LIST_HEAD(&root->allcg_list); root->number_of_cgroups = 1; cgrp->root = root; - cgrp->top_cgroup = cgrp; + cgrp->name = &root_cgroup_name; init_cgroup_housekeeping(cgrp); list_add_tail(&cgrp->allcg_node, &root->allcg_list); } @@ -1685,6 +1685,14 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, * any) is not needed */ cgroup_drop_root(opts.new_root); + + if (((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) && + root->flags != opts.flags) { + pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n"); + ret = -EINVAL; + goto drop_new_super; + } + /* no subsys rebinding, so refcounts don't change */ drop_parsed_module_refcounts(opts.subsys_mask); } @@ -1769,49 +1777,48 @@ static struct kobject *cgroup_kobj; * @buf: the buffer to write the path into * @buflen: the length of the buffer * - * Called with cgroup_mutex held or else with an RCU-protected cgroup - * reference. Writes path of cgroup into buf. Returns 0 on success, - * -errno on error. + * Writes path of cgroup into buf. Returns 0 on success, -errno on error. + * + * We can't generate cgroup path using dentry->d_name, as accessing + * dentry->name must be protected by irq-unsafe dentry->d_lock or parent + * inode's i_mutex, while on the other hand cgroup_path() can be called + * with some irq-safe spinlocks held. */ int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) { - struct dentry *dentry = cgrp->dentry; + int ret = -ENAMETOOLONG; char *start; - rcu_lockdep_assert(rcu_read_lock_held() || cgroup_lock_is_held(), - "cgroup_path() called without proper locking"); - - if (cgrp == dummytop) { - /* - * Inactive subsystems have no dentry for their root - * cgroup - */ - strcpy(buf, "/"); + if (!cgrp->parent) { + if (strlcpy(buf, "/", buflen) >= buflen) + return -ENAMETOOLONG; return 0; } start = buf + buflen - 1; - *start = '\0'; - for (;;) { - int len = dentry->d_name.len; + rcu_read_lock(); + do { + const char *name = cgroup_name(cgrp); + int len; + + len = strlen(name); if ((start -= len) < buf) - return -ENAMETOOLONG; - memcpy(start, dentry->d_name.name, len); - cgrp = cgrp->parent; - if (!cgrp) - break; + goto out; + memcpy(start, name, len); - dentry = cgrp->dentry; - if (!cgrp->parent) - continue; if (--start < buf) - return -ENAMETOOLONG; + goto out; *start = '/'; - } + + cgrp = cgrp->parent; + } while (cgrp->parent); + ret = 0; memmove(buf, start, buf + buflen - start); - return 0; +out: + rcu_read_unlock(); + return ret; } EXPORT_SYMBOL_GPL(cgroup_path); @@ -1900,7 +1907,7 @@ EXPORT_SYMBOL_GPL(cgroup_taskset_size); * * Must be called with cgroup_mutex and threadgroup locked. */ -static void cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp, +static void cgroup_task_migrate(struct cgroup *oldcgrp, struct task_struct *tsk, struct css_set *newcg) { struct css_set *oldcg; @@ -1933,121 +1940,22 @@ static void cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp, } /** - * cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp' - * @cgrp: the cgroup the task is attaching to - * @tsk: the task to be attached - * - * Call with cgroup_mutex and threadgroup locked. May take task_lock of - * @tsk during call. - */ -int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) -{ - int retval = 0; - struct cgroup_subsys *ss, *failed_ss = NULL; - struct cgroup *oldcgrp; - struct cgroupfs_root *root = cgrp->root; - struct cgroup_taskset tset = { }; - struct css_set *newcg; - - /* @tsk either already exited or can't exit until the end */ - if (tsk->flags & PF_EXITING) - return -ESRCH; - - /* Nothing to do if the task is already in that cgroup */ - oldcgrp = task_cgroup_from_root(tsk, root); - if (cgrp == oldcgrp) - return 0; - - tset.single.task = tsk; - tset.single.cgrp = oldcgrp; - - for_each_subsys(root, ss) { - if (ss->can_attach) { - retval = ss->can_attach(cgrp, &tset); - if (retval) { - /* - * Remember on which subsystem the can_attach() - * failed, so that we only call cancel_attach() - * against the subsystems whose can_attach() - * succeeded. (See below) - */ - failed_ss = ss; - goto out; - } - } - } - - newcg = find_css_set(tsk->cgroups, cgrp); - if (!newcg) { - retval = -ENOMEM; - goto out; - } - - cgroup_task_migrate(cgrp, oldcgrp, tsk, newcg); - - for_each_subsys(root, ss) { - if (ss->attach) - ss->attach(cgrp, &tset); - } - -out: - if (retval) { - for_each_subsys(root, ss) { - if (ss == failed_ss) - /* - * This subsystem was the one that failed the - * can_attach() check earlier, so we don't need - * to call cancel_attach() against it or any - * remaining subsystems. - */ - break; - if (ss->cancel_attach) - ss->cancel_attach(cgrp, &tset); - } - } - return retval; -} - -/** - * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' - * @from: attach to all cgroups of a given task - * @tsk: the task to be attached - */ -int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) -{ - struct cgroupfs_root *root; - int retval = 0; - - cgroup_lock(); - for_each_active_root(root) { - struct cgroup *from_cg = task_cgroup_from_root(from, root); - - retval = cgroup_attach_task(from_cg, tsk); - if (retval) - break; - } - cgroup_unlock(); - - return retval; -} -EXPORT_SYMBOL_GPL(cgroup_attach_task_all); - -/** - * cgroup_attach_proc - attach all threads in a threadgroup to a cgroup + * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup * @cgrp: the cgroup to attach to - * @leader: the threadgroup leader task_struct of the group to be attached + * @tsk: the task or the leader of the threadgroup to be attached + * @threadgroup: attach the whole threadgroup? * * Call holding cgroup_mutex and the group_rwsem of the leader. Will take - * task_lock of each thread in leader's threadgroup individually in turn. + * task_lock of @tsk or each thread in the threadgroup individually in turn. */ -static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) +static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, + bool threadgroup) { int retval, i, group_size; struct cgroup_subsys *ss, *failed_ss = NULL; - /* guaranteed to be initialized later, but the compiler needs this */ struct cgroupfs_root *root = cgrp->root; /* threadgroup list cursor and array */ - struct task_struct *tsk; + struct task_struct *leader = tsk; struct task_and_cgroup *tc; struct flex_array *group; struct cgroup_taskset tset = { }; @@ -2059,17 +1967,19 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) * group - group_rwsem prevents new threads from appearing, and if * threads exit, this will just be an over-estimate. */ - group_size = get_nr_threads(leader); + if (threadgroup) + group_size = get_nr_threads(tsk); + else + group_size = 1; /* flex_array supports very large thread-groups better than kmalloc. */ group = flex_array_alloc(sizeof(*tc), group_size, GFP_KERNEL); if (!group) return -ENOMEM; /* pre-allocate to guarantee space while iterating in rcu read-side. */ - retval = flex_array_prealloc(group, 0, group_size - 1, GFP_KERNEL); + retval = flex_array_prealloc(group, 0, group_size, GFP_KERNEL); if (retval) goto out_free_group_list; - tsk = leader; i = 0; /* * Prevent freeing of tasks while we take a snapshot. Tasks that are @@ -2098,6 +2008,9 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) retval = flex_array_put(group, i, &ent, GFP_ATOMIC); BUG_ON(retval != 0); i++; + + if (!threadgroup) + break; } while_each_thread(leader, tsk); rcu_read_unlock(); /* remember the number of threads in the array for later. */ @@ -2143,7 +2056,7 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) */ for (i = 0; i < group_size; i++) { tc = flex_array_get(group, i); - cgroup_task_migrate(cgrp, tc->cgrp, tc->task, tc->cg); + cgroup_task_migrate(tc->cgrp, tc->task, tc->cg); } /* nothing is sensitive to fork() after this point. */ @@ -2251,17 +2164,42 @@ retry_find_task: put_task_struct(tsk); goto retry_find_task; } - ret = cgroup_attach_proc(cgrp, tsk); - } else - ret = cgroup_attach_task(cgrp, tsk); + } + + ret = cgroup_attach_task(cgrp, tsk, threadgroup); + threadgroup_unlock(tsk); put_task_struct(tsk); out_unlock_cgroup: - cgroup_unlock(); + mutex_unlock(&cgroup_mutex); return ret; } +/** + * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' + * @from: attach to all cgroups of a given task + * @tsk: the task to be attached + */ +int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) +{ + struct cgroupfs_root *root; + int retval = 0; + + mutex_lock(&cgroup_mutex); + for_each_active_root(root) { + struct cgroup *from_cg = task_cgroup_from_root(from, root); + + retval = cgroup_attach_task(from_cg, tsk, false); + if (retval) + break; + } + mutex_unlock(&cgroup_mutex); + + return retval; +} +EXPORT_SYMBOL_GPL(cgroup_attach_task_all); + static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid) { return attach_task_by_pid(cgrp, pid, false); @@ -2272,24 +2210,6 @@ static int cgroup_procs_write(struct cgroup *cgrp, struct cftype *cft, u64 tgid) return attach_task_by_pid(cgrp, tgid, true); } -/** - * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive. - * @cgrp: the cgroup to be checked for liveness - * - * On success, returns true; the lock should be later released with - * cgroup_unlock(). On failure returns false with no lock held. - */ -bool cgroup_lock_live_group(struct cgroup *cgrp) -{ - mutex_lock(&cgroup_mutex); - if (cgroup_is_removed(cgrp)) { - mutex_unlock(&cgroup_mutex); - return false; - } - return true; -} -EXPORT_SYMBOL_GPL(cgroup_lock_live_group); - static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft, const char *buffer) { @@ -2301,7 +2221,7 @@ static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft, mutex_lock(&cgroup_root_mutex); strcpy(cgrp->root->release_agent_path, buffer); mutex_unlock(&cgroup_root_mutex); - cgroup_unlock(); + mutex_unlock(&cgroup_mutex); return 0; } @@ -2312,7 +2232,14 @@ static int cgroup_release_agent_show(struct cgroup *cgrp, struct cftype *cft, return -ENODEV; seq_puts(seq, cgrp->root->release_agent_path); seq_putc(seq, '\n'); - cgroup_unlock(); + mutex_unlock(&cgroup_mutex); + return 0; +} + +static int cgroup_sane_behavior_show(struct cgroup *cgrp, struct cftype *cft, + struct seq_file *seq) +{ + seq_printf(seq, "%d\n", cgroup_sane_behavior(cgrp)); return 0; } @@ -2537,13 +2464,40 @@ static int cgroup_file_release(struct inode *inode, struct file *file) static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) { + int ret; + struct cgroup_name *name, *old_name; + struct cgroup *cgrp; + + /* + * It's convinient to use parent dir's i_mutex to protected + * cgrp->name. + */ + lockdep_assert_held(&old_dir->i_mutex); + if (!S_ISDIR(old_dentry->d_inode->i_mode)) return -ENOTDIR; if (new_dentry->d_inode) return -EEXIST; if (old_dir != new_dir) return -EIO; - return simple_rename(old_dir, old_dentry, new_dir, new_dentry); + + cgrp = __d_cgrp(old_dentry); + + name = cgroup_alloc_name(new_dentry); + if (!name) + return -ENOMEM; + + ret = simple_rename(old_dir, old_dentry, new_dir, new_dentry); + if (ret) { + kfree(name); + return ret; + } + + old_name = cgrp->name; + rcu_assign_pointer(cgrp->name, name); + + kfree_rcu(old_name, rcu_head); + return 0; } static struct simple_xattrs *__d_xattrs(struct dentry *dentry) @@ -2551,13 +2505,13 @@ static struct simple_xattrs *__d_xattrs(struct dentry *dentry) if (S_ISDIR(dentry->d_inode->i_mode)) return &__d_cgrp(dentry)->xattrs; else - return &__d_cft(dentry)->xattrs; + return &__d_cfe(dentry)->xattrs; } static inline int xattr_enabled(struct dentry *dentry) { struct cgroupfs_root *root = dentry->d_sb->s_fs_info; - return test_bit(ROOT_XATTR, &root->flags); + return root->flags & CGRP_ROOT_XATTR; } static bool is_valid_xattr(const char *name) @@ -2727,9 +2681,7 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, umode_t mode; char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 }; - simple_xattrs_init(&cft->xattrs); - - if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) { + if (subsys && !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) { strcpy(name, subsys->name); strcat(name, "."); } @@ -2753,6 +2705,7 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, cfe->type = (void *)cft; cfe->dentry = dentry; dentry->d_fsdata = cfe; + simple_xattrs_init(&cfe->xattrs); list_add_tail(&cfe->node, &parent->files); cfe = NULL; } @@ -2770,6 +2723,8 @@ static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys, for (cft = cfts; cft->name[0] != '\0'; cft++) { /* does cft->flags tell us to skip this file on @cgrp? */ + if ((cft->flags & CFTYPE_INSANE) && cgroup_sane_behavior(cgrp)) + continue; if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent) continue; if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent) @@ -3300,6 +3255,34 @@ int cgroup_scan_tasks(struct cgroup_scanner *scan) return 0; } +static void cgroup_transfer_one_task(struct task_struct *task, + struct cgroup_scanner *scan) +{ + struct cgroup *new_cgroup = scan->data; + + mutex_lock(&cgroup_mutex); + cgroup_attach_task(new_cgroup, task, false); + mutex_unlock(&cgroup_mutex); +} + +/** + * cgroup_trasnsfer_tasks - move tasks from one cgroup to another + * @to: cgroup to which the tasks will be moved + * @from: cgroup in which the tasks currently reside + */ +int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) +{ + struct cgroup_scanner scan; + + scan.cg = from; + scan.test_task = NULL; /* select all tasks in cgroup */ + scan.process_task = cgroup_transfer_one_task; + scan.heap = NULL; + scan.data = to; + + return cgroup_scan_tasks(&scan); +} + /* * Stuff for reading the 'tasks'/'procs' files. * @@ -3362,35 +3345,14 @@ static void pidlist_free(void *p) else kfree(p); } -static void *pidlist_resize(void *p, int newcount) -{ - void *newlist; - /* note: if new alloc fails, old p will still be valid either way */ - if (is_vmalloc_addr(p)) { - newlist = vmalloc(newcount * sizeof(pid_t)); - if (!newlist) - return NULL; - memcpy(newlist, p, newcount * sizeof(pid_t)); - vfree(p); - } else { - newlist = krealloc(p, newcount * sizeof(pid_t), GFP_KERNEL); - } - return newlist; -} /* * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries - * If the new stripped list is sufficiently smaller and there's enough memory - * to allocate a new buffer, will let go of the unneeded memory. Returns the - * number of unique elements. + * Returns the number of unique elements. */ -/* is the size difference enough that we should re-allocate the array? */ -#define PIDLIST_REALLOC_DIFFERENCE(old, new) ((old) - PAGE_SIZE >= (new)) -static int pidlist_uniq(pid_t **p, int length) +static int pidlist_uniq(pid_t *list, int length) { int src, dest = 1; - pid_t *list = *p; - pid_t *newlist; /* * we presume the 0th element is unique, so i starts at 1. trivial @@ -3411,16 +3373,6 @@ static int pidlist_uniq(pid_t **p, int length) dest++; } after: - /* - * if the length difference is large enough, we want to allocate a - * smaller buffer to save memory. if this fails due to out of memory, - * we'll just stay with what we've got. - */ - if (PIDLIST_REALLOC_DIFFERENCE(length, dest)) { - newlist = pidlist_resize(list, dest); - if (newlist) - *p = newlist; - } return dest; } @@ -3516,7 +3468,7 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, /* now sort & (if procs) strip out duplicates */ sort(array, length, sizeof(pid_t), cmppid, NULL); if (type == CGROUP_FILE_PROCS) - length = pidlist_uniq(&array, length); + length = pidlist_uniq(array, length); l = cgroup_pidlist_find(cgrp, type); if (!l) { pidlist_free(array); @@ -3930,11 +3882,7 @@ static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft, if (ret) goto fail; - if (efile->f_op->poll(efile, &event->pt) & POLLHUP) { - event->cft->unregister_event(cgrp, event->cft, event->eventfd); - ret = 0; - goto fail; - } + efile->f_op->poll(efile, &event->pt); /* * Events should be removed after rmdir of cgroup directory, but before @@ -4016,10 +3964,16 @@ static struct cftype files[] = { }, { .name = "cgroup.clone_children", + .flags = CFTYPE_INSANE, .read_u64 = cgroup_clone_children_read, .write_u64 = cgroup_clone_children_write, }, { + .name = "cgroup.sane_behavior", + .flags = CFTYPE_ONLY_ON_ROOT, + .read_seq_string = cgroup_sane_behavior_show, + }, + { .name = "release_agent", .flags = CFTYPE_ONLY_ON_ROOT, .read_seq_string = cgroup_release_agent_show, @@ -4131,17 +4085,8 @@ static void offline_css(struct cgroup_subsys *ss, struct cgroup *cgrp) if (!(css->flags & CSS_ONLINE)) return; - /* - * css_offline() should be called with cgroup_mutex unlocked. See - * 3fa59dfbc3 ("cgroup: fix potential deadlock in pre_destroy") for - * details. This temporary unlocking should go away once - * cgroup_mutex is unexported from controllers. - */ - if (ss->css_offline) { - mutex_unlock(&cgroup_mutex); + if (ss->css_offline) ss->css_offline(cgrp); - mutex_lock(&cgroup_mutex); - } cgrp->subsys[ss->subsys_id]->flags &= ~CSS_ONLINE; } @@ -4158,6 +4103,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, umode_t mode) { struct cgroup *cgrp; + struct cgroup_name *name; struct cgroupfs_root *root = parent->root; int err = 0; struct cgroup_subsys *ss; @@ -4168,9 +4114,14 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, if (!cgrp) return -ENOMEM; + name = cgroup_alloc_name(dentry); + if (!name) + goto err_free_cgrp; + rcu_assign_pointer(cgrp->name, name); + cgrp->id = ida_simple_get(&root->cgroup_ida, 1, 0, GFP_KERNEL); if (cgrp->id < 0) - goto err_free_cgrp; + goto err_free_name; /* * Only live parents can have children. Note that the liveliness @@ -4198,7 +4149,6 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, cgrp->parent = parent; cgrp->root = parent->root; - cgrp->top_cgroup = parent->top_cgroup; if (notify_on_release(parent)) set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); @@ -4241,6 +4191,9 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, for_each_subsys(root, ss) dget(dentry); + /* hold a ref to the parent's dentry */ + dget(parent->dentry); + /* creation succeeded, notify subsystems */ for_each_subsys(root, ss) { err = online_css(ss, cgrp); @@ -4276,6 +4229,8 @@ err_free_all: deactivate_super(sb); err_free_id: ida_simple_remove(&root->cgroup_ida, cgrp->id); +err_free_name: + kfree(rcu_dereference_raw(cgrp->name)); err_free_cgrp: kfree(cgrp); return err; @@ -4295,56 +4250,13 @@ static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) return cgroup_create(c_parent, dentry, mode | S_IFDIR); } -/* - * Check the reference count on each subsystem. Since we already - * established that there are no tasks in the cgroup, if the css refcount - * is also 1, then there should be no outstanding references, so the - * subsystem is safe to destroy. We scan across all subsystems rather than - * using the per-hierarchy linked list of mounted subsystems since we can - * be called via check_for_release() with no synchronization other than - * RCU, and the subsystem linked list isn't RCU-safe. - */ -static int cgroup_has_css_refs(struct cgroup *cgrp) -{ - int i; - - /* - * We won't need to lock the subsys array, because the subsystems - * we're concerned about aren't going anywhere since our cgroup root - * has a reference on them. - */ - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { - struct cgroup_subsys *ss = subsys[i]; - struct cgroup_subsys_state *css; - - /* Skip subsystems not present or not in this hierarchy */ - if (ss == NULL || ss->root != cgrp->root) - continue; - - css = cgrp->subsys[ss->subsys_id]; - /* - * When called from check_for_release() it's possible - * that by this point the cgroup has been removed - * and the css deleted. But a false-positive doesn't - * matter, since it can only happen if the cgroup - * has been deleted and hence no longer needs the - * release agent to be called anyway. - */ - if (css && css_refcnt(css) > 1) - return 1; - } - return 0; -} - static int cgroup_destroy_locked(struct cgroup *cgrp) __releases(&cgroup_mutex) __acquires(&cgroup_mutex) { struct dentry *d = cgrp->dentry; struct cgroup *parent = cgrp->parent; - DEFINE_WAIT(wait); struct cgroup_event *event, *tmp; struct cgroup_subsys *ss; - LIST_HEAD(tmp_list); lockdep_assert_held(&d->d_inode->i_mutex); lockdep_assert_held(&cgroup_mutex); @@ -4935,17 +4847,17 @@ void cgroup_post_fork(struct task_struct *child) * and addition to css_set. */ if (need_forkexit_callback) { - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { + /* + * fork/exit callbacks are supported only for builtin + * subsystems, and the builtin section of the subsys + * array is immutable, so we don't need to lock the + * subsys array here. On the other hand, modular section + * of the array can be freed at module unload, so we + * can't touch that. + */ + for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { struct cgroup_subsys *ss = subsys[i]; - /* - * fork/exit callbacks are supported only for - * builtin subsystems and we don't need further - * synchronization as they never go away. - */ - if (!ss || ss->module) - continue; - if (ss->fork) ss->fork(child); } @@ -5010,13 +4922,13 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks) tsk->cgroups = &init_css_set; if (run_callbacks && need_forkexit_callback) { - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { + /* + * fork/exit callbacks are supported only for builtin + * subsystems, see cgroup_post_fork() for details. + */ + for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { struct cgroup_subsys *ss = subsys[i]; - /* modular subsystems can't use callbacks */ - if (!ss || ss->module) - continue; - if (ss->exit) { struct cgroup *old_cgrp = rcu_dereference_raw(cg->subsys[i])->cgroup; @@ -5030,44 +4942,19 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks) put_css_set_taskexit(cg); } -/** - * cgroup_is_descendant - see if @cgrp is a descendant of @task's cgrp - * @cgrp: the cgroup in question - * @task: the task in question - * - * See if @cgrp is a descendant of @task's cgroup in the appropriate - * hierarchy. - * - * If we are sending in dummytop, then presumably we are creating - * the top cgroup in the subsystem. - * - * Called only by the ns (nsproxy) cgroup. - */ -int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task) -{ - int ret; - struct cgroup *target; - - if (cgrp == dummytop) - return 1; - - target = task_cgroup_from_root(task, cgrp->root); - while (cgrp != target && cgrp!= cgrp->top_cgroup) - cgrp = cgrp->parent; - ret = (cgrp == target); - return ret; -} - static void check_for_release(struct cgroup *cgrp) { /* All of these checks rely on RCU to keep the cgroup * structure alive */ - if (cgroup_is_releasable(cgrp) && !atomic_read(&cgrp->count) - && list_empty(&cgrp->children) && !cgroup_has_css_refs(cgrp)) { - /* Control Group is currently removeable. If it's not + if (cgroup_is_releasable(cgrp) && + !atomic_read(&cgrp->count) && list_empty(&cgrp->children)) { + /* + * Control Group is currently removeable. If it's not * already queued for a userspace notification, queue - * it now */ + * it now + */ int need_schedule_work = 0; + raw_spin_lock(&release_list_lock); if (!cgroup_is_removed(cgrp) && list_empty(&cgrp->release_list)) { @@ -5100,24 +4987,11 @@ EXPORT_SYMBOL_GPL(__css_tryget); /* Caller must verify that the css is not for root cgroup */ void __css_put(struct cgroup_subsys_state *css) { - struct cgroup *cgrp = css->cgroup; int v; - rcu_read_lock(); v = css_unbias_refcnt(atomic_dec_return(&css->refcnt)); - - switch (v) { - case 1: - if (notify_on_release(cgrp)) { - set_bit(CGRP_RELEASABLE, &cgrp->flags); - check_for_release(cgrp); - } - break; - case 0: + if (v == 0) schedule_work(&css->dput_work); - break; - } - rcu_read_unlock(); } EXPORT_SYMBOL_GPL(__css_put); diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 027a6f6..1233112 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -265,17 +265,6 @@ static DEFINE_MUTEX(cpuset_mutex); static DEFINE_MUTEX(callback_mutex); /* - * cpuset_buffer_lock protects both the cpuset_name and cpuset_nodelist - * buffers. They are statically allocated to prevent using excess stack - * when calling cpuset_print_task_mems_allowed(). - */ -#define CPUSET_NAME_LEN (128) -#define CPUSET_NODELIST_LEN (256) -static char cpuset_name[CPUSET_NAME_LEN]; -static char cpuset_nodelist[CPUSET_NODELIST_LEN]; -static DEFINE_SPINLOCK(cpuset_buffer_lock); - -/* * CPU / memory hotplug is handled asynchronously. */ static struct workqueue_struct *cpuset_propagate_hotplug_wq; @@ -780,25 +769,26 @@ static void rebuild_sched_domains_locked(void) lockdep_assert_held(&cpuset_mutex); get_online_cpus(); + /* + * We have raced with CPU hotplug. Don't do anything to avoid + * passing doms with offlined cpu to partition_sched_domains(). + * Anyways, hotplug work item will rebuild sched domains. + */ + if (!cpumask_equal(top_cpuset.cpus_allowed, cpu_active_mask)) + goto out; + /* Generate domain masks and attrs */ ndoms = generate_sched_domains(&doms, &attr); /* Have scheduler rebuild the domains */ partition_sched_domains(ndoms, doms, attr); - +out: put_online_cpus(); } #else /* !CONFIG_SMP */ static void rebuild_sched_domains_locked(void) { } - -static int generate_sched_domains(cpumask_var_t **domains, - struct sched_domain_attr **attributes) -{ - *domains = NULL; - return 1; -} #endif /* CONFIG_SMP */ void rebuild_sched_domains(void) @@ -2005,50 +1995,6 @@ int __init cpuset_init(void) return 0; } -/** - * cpuset_do_move_task - move a given task to another cpuset - * @tsk: pointer to task_struct the task to move - * @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner - * - * Called by cgroup_scan_tasks() for each task in a cgroup. - * Return nonzero to stop the walk through the tasks. - */ -static void cpuset_do_move_task(struct task_struct *tsk, - struct cgroup_scanner *scan) -{ - struct cgroup *new_cgroup = scan->data; - - cgroup_lock(); - cgroup_attach_task(new_cgroup, tsk); - cgroup_unlock(); -} - -/** - * move_member_tasks_to_cpuset - move tasks from one cpuset to another - * @from: cpuset in which the tasks currently reside - * @to: cpuset to which the tasks will be moved - * - * Called with cpuset_mutex held - * callback_mutex must not be held, as cpuset_attach() will take it. - * - * The cgroup_scan_tasks() function will scan all the tasks in a cgroup, - * calling callback functions for each. - */ -static void move_member_tasks_to_cpuset(struct cpuset *from, struct cpuset *to) -{ - struct cgroup_scanner scan; - - scan.cg = from->css.cgroup; - scan.test_task = NULL; /* select all tasks in cgroup */ - scan.process_task = cpuset_do_move_task; - scan.heap = NULL; - scan.data = to->css.cgroup; - - if (cgroup_scan_tasks(&scan)) - printk(KERN_ERR "move_member_tasks_to_cpuset: " - "cgroup_scan_tasks failed\n"); -} - /* * If CPU and/or memory hotplug handlers, below, unplug any CPUs * or memory nodes, we need to walk over the cpuset hierarchy, @@ -2069,7 +2015,12 @@ static void remove_tasks_in_empty_cpuset(struct cpuset *cs) nodes_empty(parent->mems_allowed)) parent = parent_cs(parent); - move_member_tasks_to_cpuset(cs, parent); + if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) { + rcu_read_lock(); + printk(KERN_ERR "cpuset: failed to transfer tasks out of empty cpuset %s\n", + cgroup_name(cs->css.cgroup)); + rcu_read_unlock(); + } } /** @@ -2222,17 +2173,8 @@ static void cpuset_hotplug_workfn(struct work_struct *work) flush_workqueue(cpuset_propagate_hotplug_wq); /* rebuild sched domains if cpus_allowed has changed */ - if (cpus_updated) { - struct sched_domain_attr *attr; - cpumask_var_t *doms; - int ndoms; - - mutex_lock(&cpuset_mutex); - ndoms = generate_sched_domains(&doms, &attr); - mutex_unlock(&cpuset_mutex); - - partition_sched_domains(ndoms, doms, attr); - } + if (cpus_updated) + rebuild_sched_domains(); } void cpuset_update_active_cpus(bool cpu_online) @@ -2594,6 +2536,8 @@ int cpuset_mems_allowed_intersects(const struct task_struct *tsk1, return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed); } +#define CPUSET_NODELIST_LEN (256) + /** * cpuset_print_task_mems_allowed - prints task's cpuset and mems_allowed * @task: pointer to task_struct of some task. @@ -2604,25 +2548,22 @@ int cpuset_mems_allowed_intersects(const struct task_struct *tsk1, */ void cpuset_print_task_mems_allowed(struct task_struct *tsk) { - struct dentry *dentry; + /* Statically allocated to prevent using excess stack. */ + static char cpuset_nodelist[CPUSET_NODELIST_LEN]; + static DEFINE_SPINLOCK(cpuset_buffer_lock); - dentry = task_cs(tsk)->css.cgroup->dentry; - spin_lock(&cpuset_buffer_lock); + struct cgroup *cgrp = task_cs(tsk)->css.cgroup; - if (!dentry) { - strcpy(cpuset_name, "/"); - } else { - spin_lock(&dentry->d_lock); - strlcpy(cpuset_name, (const char *)dentry->d_name.name, - CPUSET_NAME_LEN); - spin_unlock(&dentry->d_lock); - } + rcu_read_lock(); + spin_lock(&cpuset_buffer_lock); nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN, tsk->mems_allowed); printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n", - tsk->comm, cpuset_name, cpuset_nodelist); + tsk->comm, cgroup_name(cgrp), cpuset_nodelist); + spin_unlock(&cpuset_buffer_lock); + rcu_read_unlock(); } /* diff --git a/kernel/events/core.c b/kernel/events/core.c index 9fcb094..dce6e13 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -251,7 +251,22 @@ perf_cgroup_match(struct perf_event *event) struct perf_event_context *ctx = event->ctx; struct perf_cpu_context *cpuctx = __get_cpu_context(ctx); - return !event->cgrp || event->cgrp == cpuctx->cgrp; + /* @event doesn't care about cgroup */ + if (!event->cgrp) + return true; + + /* wants specific cgroup scope but @cpuctx isn't associated with any */ + if (!cpuctx->cgrp) + return false; + + /* + * Cgroup scoping is recursive. An event enabled for a cgroup is + * also enabled for all its descendant cgroups. If @cpuctx's + * cgroup is a descendant of @event's (the test covers identity + * case), it's a match. + */ + return cgroup_is_descendant(cpuctx->cgrp->css.cgroup, + event->cgrp->css.cgroup); } static inline bool perf_tryget_cgroup(struct perf_event *event) @@ -7517,12 +7532,5 @@ struct cgroup_subsys perf_subsys = { .css_free = perf_cgroup_css_free, .exit = perf_cgroup_exit, .attach = perf_cgroup_attach, - - /* - * perf_event cgroup doesn't handle nesting correctly. - * ctx->nr_cgroups adjustments should be propagated through the - * cgroup hierarchy. Fix it and remove the following. - */ - .broken_hierarchy = true, }; #endif /* CONFIG_CGROUP_PERF */ diff --git a/mm/memcontrol.c b/mm/memcontrol.c index b8dc8e4..0f1d921 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3321,52 +3321,53 @@ void mem_cgroup_destroy_cache(struct kmem_cache *cachep) schedule_work(&cachep->memcg_params->destroy); } -static char *memcg_cache_name(struct mem_cgroup *memcg, struct kmem_cache *s) -{ - char *name; - struct dentry *dentry; - - rcu_read_lock(); - dentry = rcu_dereference(memcg->css.cgroup->dentry); - rcu_read_unlock(); - - BUG_ON(dentry == NULL); - - name = kasprintf(GFP_KERNEL, "%s(%d:%s)", s->name, - memcg_cache_id(memcg), dentry->d_name.name); - - return name; -} +/* + * This lock protects updaters, not readers. We want readers to be as fast as + * they can, and they will either see NULL or a valid cache value. Our model + * allow them to see NULL, in which case the root memcg will be selected. + * + * We need this lock because multiple allocations to the same cache from a non + * will span more than one worker. Only one of them can create the cache. + */ +static DEFINE_MUTEX(memcg_cache_mutex); +/* + * Called with memcg_cache_mutex held + */ static struct kmem_cache *kmem_cache_dup(struct mem_cgroup *memcg, struct kmem_cache *s) { - char *name; struct kmem_cache *new; + static char *tmp_name = NULL; - name = memcg_cache_name(memcg, s); - if (!name) - return NULL; + lockdep_assert_held(&memcg_cache_mutex); + + /* + * kmem_cache_create_memcg duplicates the given name and + * cgroup_name for this name requires RCU context. + * This static temporary buffer is used to prevent from + * pointless shortliving allocation. + */ + if (!tmp_name) { + tmp_name = kmalloc(PATH_MAX, GFP_KERNEL); + if (!tmp_name) + return NULL; + } + + rcu_read_lock(); + snprintf(tmp_name, PATH_MAX, "%s(%d:%s)", s->name, + memcg_cache_id(memcg), cgroup_name(memcg->css.cgroup)); + rcu_read_unlock(); - new = kmem_cache_create_memcg(memcg, name, s->object_size, s->align, + new = kmem_cache_create_memcg(memcg, tmp_name, s->object_size, s->align, (s->flags & ~SLAB_PANIC), s->ctor, s); if (new) new->allocflags |= __GFP_KMEMCG; - kfree(name); return new; } -/* - * This lock protects updaters, not readers. We want readers to be as fast as - * they can, and they will either see NULL or a valid cache value. Our model - * allow them to see NULL, in which case the root memcg will be selected. - * - * We need this lock because multiple allocations to the same cache from a non - * will span more than one worker. Only one of them can create the cache. - */ -static DEFINE_MUTEX(memcg_cache_mutex); static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg, struct kmem_cache *cachep) { @@ -5912,6 +5913,7 @@ static struct cftype mem_cgroup_files[] = { }, { .name = "use_hierarchy", + .flags = CFTYPE_INSANE, .write_u64 = mem_cgroup_hierarchy_write, .read_u64 = mem_cgroup_hierarchy_read, }, @@ -6907,6 +6909,21 @@ static void mem_cgroup_move_task(struct cgroup *cont, } #endif +/* + * Cgroup retains root cgroups across [un]mount cycles making it necessary + * to verify sane_behavior flag on each mount attempt. + */ +static void mem_cgroup_bind(struct cgroup *root) +{ + /* + * use_hierarchy is forced with sane_behavior. cgroup core + * guarantees that @root doesn't have any children, so turning it + * on for the root memcg is enough. + */ + if (cgroup_sane_behavior(root)) + mem_cgroup_from_cont(root)->use_hierarchy = true; +} + struct cgroup_subsys mem_cgroup_subsys = { .name = "memory", .subsys_id = mem_cgroup_subsys_id, @@ -6917,6 +6934,7 @@ struct cgroup_subsys mem_cgroup_subsys = { .can_attach = mem_cgroup_can_attach, .cancel_attach = mem_cgroup_cancel_attach, .attach = mem_cgroup_move_task, + .bind = mem_cgroup_bind, .base_cftypes = mem_cgroup_files, .early_init = 0, .use_id = 1, diff --git a/security/device_cgroup.c b/security/device_cgroup.c index 1c69e38..dd0dc57 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -25,6 +25,12 @@ static DEFINE_MUTEX(devcgroup_mutex); +enum devcg_behavior { + DEVCG_DEFAULT_NONE, + DEVCG_DEFAULT_ALLOW, + DEVCG_DEFAULT_DENY, +}; + /* * exception list locking rules: * hold devcgroup_mutex for update/read. @@ -42,10 +48,9 @@ struct dev_exception_item { struct dev_cgroup { struct cgroup_subsys_state css; struct list_head exceptions; - enum { - DEVCG_DEFAULT_ALLOW, - DEVCG_DEFAULT_DENY, - } behavior; + enum devcg_behavior behavior; + /* temporary list for pending propagation operations */ + struct list_head propagate_pending; }; static inline struct dev_cgroup *css_to_devcgroup(struct cgroup_subsys_state *s) @@ -182,35 +187,62 @@ static void dev_exception_clean(struct dev_cgroup *dev_cgroup) __dev_exception_clean(dev_cgroup); } +static inline bool is_devcg_online(const struct dev_cgroup *devcg) +{ + return (devcg->behavior != DEVCG_DEFAULT_NONE); +} + +/** + * devcgroup_online - initializes devcgroup's behavior and exceptions based on + * parent's + * @cgroup: cgroup getting online + * returns 0 in case of success, error code otherwise + */ +static int devcgroup_online(struct cgroup *cgroup) +{ + struct dev_cgroup *dev_cgroup, *parent_dev_cgroup = NULL; + int ret = 0; + + mutex_lock(&devcgroup_mutex); + dev_cgroup = cgroup_to_devcgroup(cgroup); + if (cgroup->parent) + parent_dev_cgroup = cgroup_to_devcgroup(cgroup->parent); + + if (parent_dev_cgroup == NULL) + dev_cgroup->behavior = DEVCG_DEFAULT_ALLOW; + else { + ret = dev_exceptions_copy(&dev_cgroup->exceptions, + &parent_dev_cgroup->exceptions); + if (!ret) + dev_cgroup->behavior = parent_dev_cgroup->behavior; + } + mutex_unlock(&devcgroup_mutex); + + return ret; +} + +static void devcgroup_offline(struct cgroup *cgroup) +{ + struct dev_cgroup *dev_cgroup = cgroup_to_devcgroup(cgroup); + + mutex_lock(&devcgroup_mutex); + dev_cgroup->behavior = DEVCG_DEFAULT_NONE; + mutex_unlock(&devcgroup_mutex); +} + /* * called from kernel/cgroup.c with cgroup_lock() held. */ static struct cgroup_subsys_state *devcgroup_css_alloc(struct cgroup *cgroup) { - struct dev_cgroup *dev_cgroup, *parent_dev_cgroup; - struct cgroup *parent_cgroup; - int ret; + struct dev_cgroup *dev_cgroup; dev_cgroup = kzalloc(sizeof(*dev_cgroup), GFP_KERNEL); if (!dev_cgroup) return ERR_PTR(-ENOMEM); INIT_LIST_HEAD(&dev_cgroup->exceptions); - parent_cgroup = cgroup->parent; - - if (parent_cgroup == NULL) - dev_cgroup->behavior = DEVCG_DEFAULT_ALLOW; - else { - parent_dev_cgroup = cgroup_to_devcgroup(parent_cgroup); - mutex_lock(&devcgroup_mutex); - ret = dev_exceptions_copy(&dev_cgroup->exceptions, - &parent_dev_cgroup->exceptions); - dev_cgroup->behavior = parent_dev_cgroup->behavior; - mutex_unlock(&devcgroup_mutex); - if (ret) { - kfree(dev_cgroup); - return ERR_PTR(ret); - } - } + INIT_LIST_HEAD(&dev_cgroup->propagate_pending); + dev_cgroup->behavior = DEVCG_DEFAULT_NONE; return &dev_cgroup->css; } @@ -304,9 +336,11 @@ static int devcgroup_seq_read(struct cgroup *cgroup, struct cftype *cft, * verify if a certain access is allowed. * @dev_cgroup: dev cgroup to be tested against * @refex: new exception + * @behavior: behavior of the exception */ -static int may_access(struct dev_cgroup *dev_cgroup, - struct dev_exception_item *refex) +static bool may_access(struct dev_cgroup *dev_cgroup, + struct dev_exception_item *refex, + enum devcg_behavior behavior) { struct dev_exception_item *ex; bool match = false; @@ -330,18 +364,29 @@ static int may_access(struct dev_cgroup *dev_cgroup, break; } - /* - * In two cases we'll consider this new exception valid: - * - the dev cgroup has its default policy to allow + exception list: - * the new exception should *not* match any of the exceptions - * (behavior == DEVCG_DEFAULT_ALLOW, !match) - * - the dev cgroup has its default policy to deny + exception list: - * the new exception *should* match the exceptions - * (behavior == DEVCG_DEFAULT_DENY, match) - */ - if ((dev_cgroup->behavior == DEVCG_DEFAULT_DENY) == match) - return 1; - return 0; + if (dev_cgroup->behavior == DEVCG_DEFAULT_ALLOW) { + if (behavior == DEVCG_DEFAULT_ALLOW) { + /* the exception will deny access to certain devices */ + return true; + } else { + /* the exception will allow access to certain devices */ + if (match) + /* + * a new exception allowing access shouldn't + * match an parent's exception + */ + return false; + return true; + } + } else { + /* only behavior == DEVCG_DEFAULT_DENY allowed here */ + if (match) + /* parent has an exception that matches the proposed */ + return true; + else + return false; + } + return false; } /* @@ -358,7 +403,7 @@ static int parent_has_perm(struct dev_cgroup *childcg, if (!pcg) return 1; parent = cgroup_to_devcgroup(pcg); - return may_access(parent, ex); + return may_access(parent, ex, childcg->behavior); } /** @@ -374,6 +419,111 @@ static inline int may_allow_all(struct dev_cgroup *parent) return parent->behavior == DEVCG_DEFAULT_ALLOW; } +/** + * revalidate_active_exceptions - walks through the active exception list and + * revalidates the exceptions based on parent's + * behavior and exceptions. The exceptions that + * are no longer valid will be removed. + * Called with devcgroup_mutex held. + * @devcg: cgroup which exceptions will be checked + * + * This is one of the three key functions for hierarchy implementation. + * This function is responsible for re-evaluating all the cgroup's active + * exceptions due to a parent's exception change. + * Refer to Documentation/cgroups/devices.txt for more details. + */ +static void revalidate_active_exceptions(struct dev_cgroup *devcg) +{ + struct dev_exception_item *ex; + struct list_head *this, *tmp; + + list_for_each_safe(this, tmp, &devcg->exceptions) { + ex = container_of(this, struct dev_exception_item, list); + if (!parent_has_perm(devcg, ex)) + dev_exception_rm(devcg, ex); + } +} + +/** + * get_online_devcg - walks the cgroup tree and fills a list with the online + * groups + * @root: cgroup used as starting point + * @online: list that will be filled with online groups + * + * Must be called with devcgroup_mutex held. Grabs RCU lock. + * Because devcgroup_mutex is held, no devcg will become online or offline + * during the tree walk (see devcgroup_online, devcgroup_offline) + * A separated list is needed because propagate_behavior() and + * propagate_exception() need to allocate memory and can block. + */ +static void get_online_devcg(struct cgroup *root, struct list_head *online) +{ + struct cgroup *pos; + struct dev_cgroup *devcg; + + lockdep_assert_held(&devcgroup_mutex); + + rcu_read_lock(); + cgroup_for_each_descendant_pre(pos, root) { + devcg = cgroup_to_devcgroup(pos); + if (is_devcg_online(devcg)) + list_add_tail(&devcg->propagate_pending, online); + } + rcu_read_unlock(); +} + +/** + * propagate_exception - propagates a new exception to the children + * @devcg_root: device cgroup that added a new exception + * @ex: new exception to be propagated + * + * returns: 0 in case of success, != 0 in case of error + */ +static int propagate_exception(struct dev_cgroup *devcg_root, + struct dev_exception_item *ex) +{ + struct cgroup *root = devcg_root->css.cgroup; + struct dev_cgroup *devcg, *parent, *tmp; + int rc = 0; + LIST_HEAD(pending); + + get_online_devcg(root, &pending); + + list_for_each_entry_safe(devcg, tmp, &pending, propagate_pending) { + parent = cgroup_to_devcgroup(devcg->css.cgroup->parent); + + /* + * in case both root's behavior and devcg is allow, a new + * restriction means adding to the exception list + */ + if (devcg_root->behavior == DEVCG_DEFAULT_ALLOW && + devcg->behavior == DEVCG_DEFAULT_ALLOW) { + rc = dev_exception_add(devcg, ex); + if (rc) + break; + } else { + /* + * in the other possible cases: + * root's behavior: allow, devcg's: deny + * root's behavior: deny, devcg's: deny + * the exception will be removed + */ + dev_exception_rm(devcg, ex); + } + revalidate_active_exceptions(devcg); + + list_del_init(&devcg->propagate_pending); + } + return rc; +} + +static inline bool has_children(struct dev_cgroup *devcgroup) +{ + struct cgroup *cgrp = devcgroup->css.cgroup; + + return !list_empty(&cgrp->children); +} + /* * Modify the exception list using allow/deny rules. * CAP_SYS_ADMIN is needed for this. It's at least separate from CAP_MKNOD @@ -392,7 +542,7 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup, { const char *b; char temp[12]; /* 11 + 1 characters needed for a u32 */ - int count, rc; + int count, rc = 0; struct dev_exception_item ex; struct cgroup *p = devcgroup->css.cgroup; struct dev_cgroup *parent = NULL; @@ -410,6 +560,9 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup, case 'a': switch (filetype) { case DEVCG_ALLOW: + if (has_children(devcgroup)) + return -EINVAL; + if (!may_allow_all(parent)) return -EPERM; dev_exception_clean(devcgroup); @@ -423,6 +576,9 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup, return rc; break; case DEVCG_DENY: + if (has_children(devcgroup)) + return -EINVAL; + dev_exception_clean(devcgroup); devcgroup->behavior = DEVCG_DEFAULT_DENY; break; @@ -517,22 +673,28 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup, dev_exception_rm(devcgroup, &ex); return 0; } - return dev_exception_add(devcgroup, &ex); + rc = dev_exception_add(devcgroup, &ex); + break; case DEVCG_DENY: /* * If the default policy is to deny by default, try to remove * an matching exception instead. And be silent about it: we * don't want to break compatibility */ - if (devcgroup->behavior == DEVCG_DEFAULT_DENY) { + if (devcgroup->behavior == DEVCG_DEFAULT_DENY) dev_exception_rm(devcgroup, &ex); - return 0; - } - return dev_exception_add(devcgroup, &ex); + else + rc = dev_exception_add(devcgroup, &ex); + + if (rc) + break; + /* we only propagate new restrictions */ + rc = propagate_exception(devcgroup, &ex); + break; default: - return -EINVAL; + rc = -EINVAL; } - return 0; + return rc; } static int devcgroup_access_write(struct cgroup *cgrp, struct cftype *cft, @@ -571,17 +733,10 @@ struct cgroup_subsys devices_subsys = { .can_attach = devcgroup_can_attach, .css_alloc = devcgroup_css_alloc, .css_free = devcgroup_css_free, + .css_online = devcgroup_online, + .css_offline = devcgroup_offline, .subsys_id = devices_subsys_id, .base_cftypes = dev_cgroup_files, - - /* - * While devices cgroup has the rudimentary hierarchy support which - * checks the parent's restriction, it doesn't properly propagates - * config changes in ancestors to their descendents. A child - * should only be allowed to add more restrictions to the parent's - * configuration. Fix it and remove the following. - */ - .broken_hierarchy = true, }; /** @@ -609,7 +764,7 @@ static int __devcgroup_check_permission(short type, u32 major, u32 minor, rcu_read_lock(); dev_cgroup = task_devcgroup(current); - rc = may_access(dev_cgroup, &ex); + rc = may_access(dev_cgroup, &ex, dev_cgroup->behavior); rcu_read_unlock(); if (!rc) |
