diff options
| -rw-r--r-- | Documentation/cgroup-v2.txt | 147 | ||||
| -rw-r--r-- | fs/kernfs/dir.c | 191 | ||||
| -rw-r--r-- | fs/kernfs/mount.c | 69 | ||||
| -rw-r--r-- | fs/proc/namespaces.c | 3 | ||||
| -rw-r--r-- | include/linux/cgroup.h | 49 | ||||
| -rw-r--r-- | include/linux/kernfs.h | 11 | ||||
| -rw-r--r-- | include/linux/nsproxy.h | 2 | ||||
| -rw-r--r-- | include/linux/proc_ns.h | 4 | ||||
| -rw-r--r-- | include/uapi/linux/sched.h | 3 | ||||
| -rw-r--r-- | kernel/cgroup.c | 229 | ||||
| -rw-r--r-- | kernel/cpuset.c | 8 | ||||
| -rw-r--r-- | kernel/fork.c | 2 | ||||
| -rw-r--r-- | kernel/nsproxy.c | 19 |
13 files changed, 689 insertions, 48 deletions
diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt index bdc6773..4cc07ce 100644 --- a/Documentation/cgroup-v2.txt +++ b/Documentation/cgroup-v2.txt @@ -47,6 +47,11 @@ CONTENTS 5-3. IO 5-3-1. IO Interface Files 5-3-2. Writeback +6. Namespace + 6-1. Basics + 6-2. The Root and Views + 6-3. Migration and setns(2) + 6-4. Interaction with Other Namespaces P. Information on Kernel Programming P-1. Filesystem Support for Writeback D. Deprecated v1 Core Features @@ -1114,6 +1119,148 @@ writeback as follows. vm.dirty[_background]_ratio. +6. Namespace + +6-1. Basics + +cgroup namespace provides a mechanism to virtualize the view of the +"/proc/$PID/cgroup" file and cgroup mounts. The CLONE_NEWCGROUP clone +flag can be used with clone(2) and unshare(2) to create a new cgroup +namespace. The process running inside the cgroup namespace will have +its "/proc/$PID/cgroup" output restricted to cgroupns root. The +cgroupns root is the cgroup of the process at the time of creation of +the cgroup namespace. + +Without cgroup namespace, the "/proc/$PID/cgroup" file shows the +complete path of the cgroup of a process. In a container setup where +a set of cgroups and namespaces are intended to isolate processes the +"/proc/$PID/cgroup" file may leak potential system level information +to the isolated processes. For Example: + + # cat /proc/self/cgroup + 0::/batchjobs/container_id1 + +The path '/batchjobs/container_id1' can be considered as system-data +and undesirable to expose to the isolated processes. cgroup namespace +can be used to restrict visibility of this path. For example, before +creating a cgroup namespace, one would see: + + # ls -l /proc/self/ns/cgroup + lrwxrwxrwx 1 root root 0 2014-07-15 10:37 /proc/self/ns/cgroup -> cgroup:[4026531835] + # cat /proc/self/cgroup + 0::/batchjobs/container_id1 + +After unsharing a new namespace, the view changes. + + # ls -l /proc/self/ns/cgroup + lrwxrwxrwx 1 root root 0 2014-07-15 10:35 /proc/self/ns/cgroup -> cgroup:[4026532183] + # cat /proc/self/cgroup + 0::/ + +When some thread from a multi-threaded process unshares its cgroup +namespace, the new cgroupns gets applied to the entire process (all +the threads). This is natural for the v2 hierarchy; however, for the +legacy hierarchies, this may be unexpected. + +A cgroup namespace is alive as long as there are processes inside or +mounts pinning it. When the last usage goes away, the cgroup +namespace is destroyed. The cgroupns root and the actual cgroups +remain. + + +6-2. The Root and Views + +The 'cgroupns root' for a cgroup namespace is the cgroup in which the +process calling unshare(2) is running. For example, if a process in +/batchjobs/container_id1 cgroup calls unshare, cgroup +/batchjobs/container_id1 becomes the cgroupns root. For the +init_cgroup_ns, this is the real root ('/') cgroup. + +The cgroupns root cgroup does not change even if the namespace creator +process later moves to a different cgroup. + + # ~/unshare -c # unshare cgroupns in some cgroup + # cat /proc/self/cgroup + 0::/ + # mkdir sub_cgrp_1 + # echo 0 > sub_cgrp_1/cgroup.procs + # cat /proc/self/cgroup + 0::/sub_cgrp_1 + +Each process gets its namespace-specific view of "/proc/$PID/cgroup" + +Processes running inside the cgroup namespace will be able to see +cgroup paths (in /proc/self/cgroup) only inside their root cgroup. +From within an unshared cgroupns: + + # sleep 100000 & + [1] 7353 + # echo 7353 > sub_cgrp_1/cgroup.procs + # cat /proc/7353/cgroup + 0::/sub_cgrp_1 + +From the initial cgroup namespace, the real cgroup path will be +visible: + + $ cat /proc/7353/cgroup + 0::/batchjobs/container_id1/sub_cgrp_1 + +From a sibling cgroup namespace (that is, a namespace rooted at a +different cgroup), the cgroup path relative to its own cgroup +namespace root will be shown. For instance, if PID 7353's cgroup +namespace root is at '/batchjobs/container_id2', then it will see + + # cat /proc/7353/cgroup + 0::/../container_id2/sub_cgrp_1 + +Note that the relative path always starts with '/' to indicate that +its relative to the cgroup namespace root of the caller. + + +6-3. Migration and setns(2) + +Processes inside a cgroup namespace can move into and out of the +namespace root if they have proper access to external cgroups. For +example, from inside a namespace with cgroupns root at +/batchjobs/container_id1, and assuming that the global hierarchy is +still accessible inside cgroupns: + + # cat /proc/7353/cgroup + 0::/sub_cgrp_1 + # echo 7353 > batchjobs/container_id2/cgroup.procs + # cat /proc/7353/cgroup + 0::/../container_id2 + +Note that this kind of setup is not encouraged. A task inside cgroup +namespace should only be exposed to its own cgroupns hierarchy. + +setns(2) to another cgroup namespace is allowed when: + +(a) the process has CAP_SYS_ADMIN against its current user namespace +(b) the process has CAP_SYS_ADMIN against the target cgroup + namespace's userns + +No implicit cgroup changes happen with attaching to another cgroup +namespace. It is expected that the someone moves the attaching +process under the target cgroup namespace root. + + +6-4. Interaction with Other Namespaces + +Namespace specific cgroup hierarchy can be mounted by a process +running inside a non-init cgroup namespace. + + # mount -t cgroup2 none $MOUNT_POINT + +This will mount the unified cgroup hierarchy with cgroupns root as the +filesystem root. The process needs CAP_SYS_ADMIN against its user and +mount namespaces. + +The virtualization of /proc/self/cgroup file combined with restricting +the view of cgroup hierarchy by namespace-private cgroupfs mount +provides a properly isolated cgroup view inside the container. + + P. Information on Kernel Programming This section contains kernel programming information in the areas diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 118d033..03b688d 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -44,28 +44,122 @@ static int kernfs_name_locked(struct kernfs_node *kn, char *buf, size_t buflen) return strlcpy(buf, kn->parent ? kn->name : "/", buflen); } -static char * __must_check kernfs_path_locked(struct kernfs_node *kn, char *buf, - size_t buflen) +/* kernfs_node_depth - compute depth from @from to @to */ +static size_t kernfs_depth(struct kernfs_node *from, struct kernfs_node *to) { - char *p = buf + buflen; - int len; + size_t depth = 0; - *--p = '\0'; + while (to->parent && to != from) { + depth++; + to = to->parent; + } + return depth; +} - do { - len = strlen(kn->name); - if (p - buf < len + 1) { - buf[0] = '\0'; - p = NULL; - break; - } - p -= len; - memcpy(p, kn->name, len); - *--p = '/'; - kn = kn->parent; - } while (kn && kn->parent); +static struct kernfs_node *kernfs_common_ancestor(struct kernfs_node *a, + struct kernfs_node *b) +{ + size_t da, db; + struct kernfs_root *ra = kernfs_root(a), *rb = kernfs_root(b); - return p; + if (ra != rb) + return NULL; + + da = kernfs_depth(ra->kn, a); + db = kernfs_depth(rb->kn, b); + + while (da > db) { + a = a->parent; + da--; + } + while (db > da) { + b = b->parent; + db--; + } + + /* worst case b and a will be the same at root */ + while (b != a) { + b = b->parent; + a = a->parent; + } + + return a; +} + +/** + * kernfs_path_from_node_locked - find a pseudo-absolute path to @kn_to, + * where kn_from is treated as root of the path. + * @kn_from: kernfs node which should be treated as root for the path + * @kn_to: kernfs node to which path is needed + * @buf: buffer to copy the path into + * @buflen: size of @buf + * + * We need to handle couple of scenarios here: + * [1] when @kn_from is an ancestor of @kn_to at some level + * kn_from: /n1/n2/n3 + * kn_to: /n1/n2/n3/n4/n5 + * result: /n4/n5 + * + * [2] when @kn_from is on a different hierarchy and we need to find common + * ancestor between @kn_from and @kn_to. + * kn_from: /n1/n2/n3/n4 + * kn_to: /n1/n2/n5 + * result: /../../n5 + * OR + * kn_from: /n1/n2/n3/n4/n5 [depth=5] + * kn_to: /n1/n2/n3 [depth=3] + * result: /../.. + * + * return value: length of the string. If greater than buflen, + * then contents of buf are undefined. On error, -1 is returned. + */ +static int kernfs_path_from_node_locked(struct kernfs_node *kn_to, + struct kernfs_node *kn_from, + char *buf, size_t buflen) +{ + struct kernfs_node *kn, *common; + const char parent_str[] = "/.."; + size_t depth_from, depth_to, len = 0, nlen = 0; + char *p; + int i; + + if (!kn_from) + kn_from = kernfs_root(kn_to)->kn; + + if (kn_from == kn_to) + return strlcpy(buf, "/", buflen); + + common = kernfs_common_ancestor(kn_from, kn_to); + if (WARN_ON(!common)) + return -1; + + depth_to = kernfs_depth(common, kn_to); + depth_from = kernfs_depth(common, kn_from); + + if (buf) + buf[0] = '\0'; + + for (i = 0; i < depth_from; i++) + len += strlcpy(buf + len, parent_str, + len < buflen ? buflen - len : 0); + + /* Calculate how many bytes we need for the rest */ + for (kn = kn_to; kn != common; kn = kn->parent) + nlen += strlen(kn->name) + 1; + + if (len + nlen >= buflen) + return len + nlen; + + p = buf + len + nlen; + *p = '\0'; + for (kn = kn_to; kn != common; kn = kn->parent) { + nlen = strlen(kn->name); + p -= nlen; + memcpy(p, kn->name, nlen); + *(--p) = '/'; + } + + return len + nlen; } /** @@ -115,6 +209,34 @@ size_t kernfs_path_len(struct kernfs_node *kn) } /** + * kernfs_path_from_node - build path of node @to relative to @from. + * @from: parent kernfs_node relative to which we need to build the path + * @to: kernfs_node of interest + * @buf: buffer to copy @to's path into + * @buflen: size of @buf + * + * Builds @to's path relative to @from in @buf. @from and @to must + * be on the same kernfs-root. If @from is not parent of @to, then a relative + * path (which includes '..'s) as needed to reach from @from to @to is + * returned. + * + * If @buf isn't long enough, the return value will be greater than @buflen + * and @buf contents are undefined. + */ +int kernfs_path_from_node(struct kernfs_node *to, struct kernfs_node *from, + char *buf, size_t buflen) +{ + unsigned long flags; + int ret; + + spin_lock_irqsave(&kernfs_rename_lock, flags); + ret = kernfs_path_from_node_locked(to, from, buf, buflen); + spin_unlock_irqrestore(&kernfs_rename_lock, flags); + return ret; +} +EXPORT_SYMBOL_GPL(kernfs_path_from_node); + +/** * kernfs_path - build full path of a given node * @kn: kernfs_node of interest * @buf: buffer to copy @kn's name into @@ -127,13 +249,12 @@ size_t kernfs_path_len(struct kernfs_node *kn) */ char *kernfs_path(struct kernfs_node *kn, char *buf, size_t buflen) { - unsigned long flags; - char *p; + int ret; - spin_lock_irqsave(&kernfs_rename_lock, flags); - p = kernfs_path_locked(kn, buf, buflen); - spin_unlock_irqrestore(&kernfs_rename_lock, flags); - return p; + ret = kernfs_path_from_node(kn, NULL, buf, buflen); + if (ret < 0 || ret >= buflen) + return NULL; + return buf; } EXPORT_SYMBOL_GPL(kernfs_path); @@ -164,17 +285,25 @@ void pr_cont_kernfs_name(struct kernfs_node *kn) void pr_cont_kernfs_path(struct kernfs_node *kn) { unsigned long flags; - char *p; + int sz; spin_lock_irqsave(&kernfs_rename_lock, flags); - p = kernfs_path_locked(kn, kernfs_pr_cont_buf, - sizeof(kernfs_pr_cont_buf)); - if (p) - pr_cont("%s", p); - else - pr_cont("<name too long>"); + sz = kernfs_path_from_node_locked(kn, NULL, kernfs_pr_cont_buf, + sizeof(kernfs_pr_cont_buf)); + if (sz < 0) { + pr_cont("(error)"); + goto out; + } + + if (sz >= sizeof(kernfs_pr_cont_buf)) { + pr_cont("(name too long)"); + goto out; + } + + pr_cont("%s", kernfs_pr_cont_buf); +out: spin_unlock_irqrestore(&kernfs_rename_lock, flags); } diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c index 8eaf417..b67dbcc 100644 --- a/fs/kernfs/mount.c +++ b/fs/kernfs/mount.c @@ -14,6 +14,7 @@ #include <linux/magic.h> #include <linux/slab.h> #include <linux/pagemap.h> +#include <linux/namei.h> #include "kernfs-internal.h" @@ -62,6 +63,74 @@ struct kernfs_root *kernfs_root_from_sb(struct super_block *sb) return NULL; } +/* + * find the next ancestor in the path down to @child, where @parent was the + * ancestor whose descendant we want to find. + * + * Say the path is /a/b/c/d. @child is d, @parent is NULL. We return the root + * node. If @parent is b, then we return the node for c. + * Passing in d as @parent is not ok. + */ +static struct kernfs_node *find_next_ancestor(struct kernfs_node *child, + struct kernfs_node *parent) +{ + if (child == parent) { + pr_crit_once("BUG in find_next_ancestor: called with parent == child"); + return NULL; + } + + while (child->parent != parent) { + if (!child->parent) + return NULL; + child = child->parent; + } + + return child; +} + +/** + * kernfs_node_dentry - get a dentry for the given kernfs_node + * @kn: kernfs_node for which a dentry is needed + * @sb: the kernfs super_block + */ +struct dentry *kernfs_node_dentry(struct kernfs_node *kn, + struct super_block *sb) +{ + struct dentry *dentry; + struct kernfs_node *knparent = NULL; + + BUG_ON(sb->s_op != &kernfs_sops); + + dentry = dget(sb->s_root); + + /* Check if this is the root kernfs_node */ + if (!kn->parent) + return dentry; + + knparent = find_next_ancestor(kn, NULL); + if (WARN_ON(!knparent)) + return ERR_PTR(-EINVAL); + + do { + struct dentry *dtmp; + struct kernfs_node *kntmp; + + if (kn == knparent) + return dentry; + kntmp = find_next_ancestor(kn, knparent); + if (WARN_ON(!kntmp)) + return ERR_PTR(-EINVAL); + mutex_lock(&d_inode(dentry)->i_mutex); + dtmp = lookup_one_len(kntmp->name, dentry, strlen(kntmp->name)); + mutex_unlock(&d_inode(dentry)->i_mutex); + dput(dentry); + if (IS_ERR(dtmp)) + return dtmp; + knparent = kntmp; + dentry = dtmp; + } while (true); +} + static int kernfs_fill_super(struct super_block *sb, unsigned long magic) { struct kernfs_super_info *info = kernfs_info(sb); diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c index 276f124..72cb26f 100644 --- a/fs/proc/namespaces.c +++ b/fs/proc/namespaces.c @@ -28,6 +28,9 @@ static const struct proc_ns_operations *ns_entries[] = { &userns_operations, #endif &mntns_operations, +#ifdef CONFIG_CGROUPS + &cgroupns_operations, +#endif }; static const char *proc_ns_get_link(struct dentry *dentry, diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 2162dca..a20320c 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -17,6 +17,11 @@ #include <linux/seq_file.h> #include <linux/kernfs.h> #include <linux/jump_label.h> +#include <linux/nsproxy.h> +#include <linux/types.h> +#include <linux/ns_common.h> +#include <linux/nsproxy.h> +#include <linux/user_namespace.h> #include <linux/cgroup-defs.h> @@ -611,4 +616,48 @@ static inline void cgroup_sk_free(struct sock_cgroup_data *skcd) {} #endif /* CONFIG_CGROUP_DATA */ +struct cgroup_namespace { + atomic_t count; + struct ns_common ns; + struct user_namespace *user_ns; + struct css_set *root_cset; +}; + +extern struct cgroup_namespace init_cgroup_ns; + +#ifdef CONFIG_CGROUPS + +void free_cgroup_ns(struct cgroup_namespace *ns); + +struct cgroup_namespace *copy_cgroup_ns(unsigned long flags, + struct user_namespace *user_ns, + struct cgroup_namespace *old_ns); + +char *cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen, + struct cgroup_namespace *ns); + +#else /* !CONFIG_CGROUPS */ + +static inline void free_cgroup_ns(struct cgroup_namespace *ns) { } +static inline struct cgroup_namespace * +copy_cgroup_ns(unsigned long flags, struct user_namespace *user_ns, + struct cgroup_namespace *old_ns) +{ + return old_ns; +} + +#endif /* !CONFIG_CGROUPS */ + +static inline void get_cgroup_ns(struct cgroup_namespace *ns) +{ + if (ns) + atomic_inc(&ns->count); +} + +static inline void put_cgroup_ns(struct cgroup_namespace *ns) +{ + if (ns && atomic_dec_and_test(&ns->count)) + free_cgroup_ns(ns); +} + #endif /* _LINUX_CGROUP_H */ diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index af51df3..c06c442 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -267,8 +267,9 @@ static inline bool kernfs_ns_enabled(struct kernfs_node *kn) int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen); size_t kernfs_path_len(struct kernfs_node *kn); -char * __must_check kernfs_path(struct kernfs_node *kn, char *buf, - size_t buflen); +int kernfs_path_from_node(struct kernfs_node *root_kn, struct kernfs_node *kn, + char *buf, size_t buflen); +char *kernfs_path(struct kernfs_node *kn, char *buf, size_t buflen); void pr_cont_kernfs_name(struct kernfs_node *kn); void pr_cont_kernfs_path(struct kernfs_node *kn); struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn); @@ -283,6 +284,8 @@ struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry); struct kernfs_root *kernfs_root_from_sb(struct super_block *sb); struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn); +struct dentry *kernfs_node_dentry(struct kernfs_node *kn, + struct super_block *sb); struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops, unsigned int flags, void *priv); void kernfs_destroy_root(struct kernfs_root *root); @@ -338,8 +341,8 @@ static inline int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen) static inline size_t kernfs_path_len(struct kernfs_node *kn) { return 0; } -static inline char * __must_check kernfs_path(struct kernfs_node *kn, char *buf, - size_t buflen) +static inline char *kernfs_path(struct kernfs_node *kn, char *buf, + size_t buflen) { return NULL; } static inline void pr_cont_kernfs_name(struct kernfs_node *kn) { } diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h index 35fa08f..ac0d65b 100644 --- a/include/linux/nsproxy.h +++ b/include/linux/nsproxy.h @@ -8,6 +8,7 @@ struct mnt_namespace; struct uts_namespace; struct ipc_namespace; struct pid_namespace; +struct cgroup_namespace; struct fs_struct; /* @@ -33,6 +34,7 @@ struct nsproxy { struct mnt_namespace *mnt_ns; struct pid_namespace *pid_ns_for_children; struct net *net_ns; + struct cgroup_namespace *cgroup_ns; }; extern struct nsproxy init_nsproxy; diff --git a/include/linux/proc_ns.h b/include/linux/proc_ns.h index 42dfc61..de0e771 100644 --- a/include/linux/proc_ns.h +++ b/include/linux/proc_ns.h @@ -9,6 +9,8 @@ struct pid_namespace; struct nsproxy; struct path; +struct task_struct; +struct inode; struct proc_ns_operations { const char *name; @@ -24,6 +26,7 @@ extern const struct proc_ns_operations ipcns_operations; extern const struct proc_ns_operations pidns_operations; extern const struct proc_ns_operations userns_operations; extern const struct proc_ns_operations mntns_operations; +extern const struct proc_ns_operations cgroupns_operations; /* * We always define these enumerators @@ -34,6 +37,7 @@ enum { PROC_UTS_INIT_INO = 0xEFFFFFFEU, PROC_USER_INIT_INO = 0xEFFFFFFDU, PROC_PID_INIT_INO = 0xEFFFFFFCU, + PROC_CGROUP_INIT_INO = 0xEFFFFFFBU, }; #ifdef CONFIG_PROC_FS diff --git a/include/uapi/linux/sched.h b/include/uapi/linux/sched.h index cc89dde..5f0fe01 100644 --- a/include/uapi/linux/sched.h +++ b/include/uapi/linux/sched.h @@ -21,8 +21,7 @@ #define CLONE_DETACHED 0x00400000 /* Unused, ignored */ #define CLONE_UNTRACED 0x00800000 /* set if the tracing process can't force CLONE_PTRACE on this clone */ #define CLONE_CHILD_SETTID 0x01000000 /* set the TID in the child */ -/* 0x02000000 was previously the unused CLONE_STOPPED (Start in stopped state) - and is now available for re-use. */ +#define CLONE_NEWCGROUP 0x02000000 /* New cgroup namespace */ #define CLONE_NEWUTS 0x04000000 /* New utsname namespace */ #define CLONE_NEWIPC 0x08000000 /* New ipc namespace */ #define CLONE_NEWUSER 0x10000000 /* New user namespace */ diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 3fe02c1..671dc05 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -59,6 +59,9 @@ #include <linux/delay.h> #include <linux/atomic.h> #include <linux/cpuset.h> +#include <linux/proc_ns.h> +#include <linux/nsproxy.h> +#include <linux/proc_ns.h> #include <net/sock.h> /* @@ -215,6 +218,15 @@ static u16 have_fork_callback __read_mostly; static u16 have_exit_callback __read_mostly; static u16 have_free_callback __read_mostly; +/* cgroup namespace for init task */ +struct cgroup_namespace init_cgroup_ns = { + .count = { .counter = 2, }, + .user_ns = &init_user_ns, + .ns.ops = &cgroupns_operations, + .ns.inum = PROC_CGROUP_INIT_INO, + .root_cset = &init_css_set, +}; + /* Ditto for the can_fork callback. */ static u16 have_canfork_callback __read_mostly; @@ -2002,6 +2014,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, { bool is_v2 = fs_type == &cgroup2_fs_type; struct super_block *pinned_sb = NULL; + struct cgroup_namespace *ns = current->nsproxy->cgroup_ns; struct cgroup_subsys *ss; struct cgroup_root *root; struct cgroup_sb_opts opts; @@ -2010,6 +2023,14 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, int i; bool new_sb; + get_cgroup_ns(ns); + + /* Check if the caller has permission to mount. */ + if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN)) { + put_cgroup_ns(ns); + return ERR_PTR(-EPERM); + } + /* * The first time anyone tries to mount a cgroup, enable the list * linking each css_set to its tasks and fix up all existing tasks. @@ -2020,6 +2041,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, if (is_v2) { if (data) { pr_err("cgroup2: unknown option \"%s\"\n", (char *)data); + put_cgroup_ns(ns); return ERR_PTR(-EINVAL); } cgrp_dfl_visible = true; @@ -2125,6 +2147,16 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, goto out_unlock; } + /* + * We know this subsystem has not yet been bound. Users in a non-init + * user namespace may only mount hierarchies with no bound subsystems, + * i.e. 'none,name=user1' + */ + if (!opts.none && !capable(CAP_SYS_ADMIN)) { + ret = -EPERM; + goto out_unlock; + } + root = kzalloc(sizeof(*root), GFP_KERNEL); if (!root) { ret = -ENOMEM; @@ -2143,12 +2175,37 @@ out_free: kfree(opts.release_agent); kfree(opts.name); - if (ret) + if (ret) { + put_cgroup_ns(ns); return ERR_PTR(ret); + } out_mount: dentry = kernfs_mount(fs_type, flags, root->kf_root, is_v2 ? CGROUP2_SUPER_MAGIC : CGROUP_SUPER_MAGIC, &new_sb); + + /* + * In non-init cgroup namespace, instead of root cgroup's + * dentry, we return the dentry corresponding to the + * cgroupns->root_cgrp. + */ + if (!IS_ERR(dentry) && ns != &init_cgroup_ns) { + struct dentry *nsdentry; + struct cgroup *cgrp; + + mutex_lock(&cgroup_mutex); + spin_lock_bh(&css_set_lock); + + cgrp = cset_cgroup_from_root(ns->root_cset, root); + + spin_unlock_bh(&css_set_lock); + mutex_unlock(&cgroup_mutex); + + nsdentry = kernfs_node_dentry(cgrp->kn, dentry->d_sb); + dput(dentry); + dentry = nsdentry; + } + if (IS_ERR(dentry) || !new_sb) cgroup_put(&root->cgrp); @@ -2161,6 +2218,7 @@ out_mount: deactivate_super(pinned_sb); } + put_cgroup_ns(ns); return dentry; } @@ -2189,14 +2247,45 @@ static struct file_system_type cgroup_fs_type = { .name = "cgroup", .mount = cgroup_mount, .kill_sb = cgroup_kill_sb, + .fs_flags = FS_USERNS_MOUNT, }; static struct file_system_type cgroup2_fs_type = { .name = "cgroup2", .mount = cgroup_mount, .kill_sb = cgroup_kill_sb, + .fs_flags = FS_USERNS_MOUNT, }; +static char *cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen, + struct cgroup_namespace *ns) +{ + struct cgroup *root = cset_cgroup_from_root(ns->root_cset, cgrp->root); + int ret; + + ret = kernfs_path_from_node(cgrp->kn, root->kn, buf, buflen); + if (ret < 0 || ret >= buflen) + return NULL; + return buf; +} + +char *cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen, + struct cgroup_namespace *ns) +{ + char *ret; + + mutex_lock(&cgroup_mutex); + spin_lock_bh(&css_set_lock); + + ret = cgroup_path_ns_locked(cgrp, buf, buflen, ns); + + spin_unlock_bh(&css_set_lock); + mutex_unlock(&cgroup_mutex); + + return ret; +} +EXPORT_SYMBOL_GPL(cgroup_path_ns); + /** * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy * @task: target task @@ -2224,7 +2313,7 @@ char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen) if (root) { cgrp = task_cgroup_from_root(task, root); - path = cgroup_path(cgrp, buf, buflen); + path = cgroup_path_ns_locked(cgrp, buf, buflen, &init_cgroup_ns); } else { /* if no hierarchy exists, everyone is in "/" */ if (strlcpy(buf, "/", buflen) < buflen) @@ -5450,6 +5539,8 @@ int __init cgroup_init(void) BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files)); BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files)); + get_user_ns(init_cgroup_ns.user_ns); + mutex_lock(&cgroup_mutex); /* @@ -5601,7 +5692,8 @@ int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns, * " (deleted)" is appended to the cgroup path. */ if (cgroup_on_dfl(cgrp) || !(tsk->flags & PF_EXITING)) { - path = cgroup_path(cgrp, buf, PATH_MAX); + path = cgroup_path_ns_locked(cgrp, buf, PATH_MAX, + current->nsproxy->cgroup_ns); if (!path) { retval = -ENAMETOOLONG; goto out_unlock; @@ -5886,7 +5978,9 @@ static void cgroup_release_agent(struct work_struct *work) if (!pathbuf || !agentbuf) goto out; - path = cgroup_path(cgrp, pathbuf, PATH_MAX); + spin_lock_bh(&css_set_lock); + path = cgroup_path_ns_locked(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns); + spin_unlock_bh(&css_set_lock); if (!path) goto out; @@ -6098,6 +6192,133 @@ void cgroup_sk_free(struct sock_cgroup_data *skcd) #endif /* CONFIG_SOCK_CGROUP_DATA */ +/* cgroup namespaces */ + +static struct cgroup_namespace *alloc_cgroup_ns(void) +{ + struct cgroup_namespace *new_ns; + int ret; + + new_ns = kzalloc(sizeof(struct cgroup_namespace), GFP_KERNEL); + if (!new_ns) + return ERR_PTR(-ENOMEM); + ret = ns_alloc_inum(&new_ns->ns); + if (ret) { + kfree(new_ns); + return ERR_PTR(ret); + } + atomic_set(&new_ns->count, 1); + new_ns->ns.ops = &cgroupns_operations; + return new_ns; +} + +void free_cgroup_ns(struct cgroup_namespace *ns) +{ + put_css_set(ns->root_cset); + put_user_ns(ns->user_ns); + ns_free_inum(&ns->ns); + kfree(ns); +} +EXPORT_SYMBOL(free_cgroup_ns); + +struct cgroup_namespace *copy_cgroup_ns(unsigned long flags, + struct user_namespace *user_ns, + struct cgroup_namespace *old_ns) +{ + struct cgroup_namespace *new_ns; + struct css_set *cset; + + BUG_ON(!old_ns); + + if (!(flags & CLONE_NEWCGROUP)) { + get_cgroup_ns(old_ns); + return old_ns; + } + + /* Allow only sysadmin to create cgroup namespace. */ + if (!ns_capable(user_ns, CAP_SYS_ADMIN)) + return ERR_PTR(-EPERM); + + mutex_lock(&cgroup_mutex); + spin_lock_bh(&css_set_lock); + + cset = task_css_set(current); + get_css_set(cset); + + spin_unlock_bh(&css_set_lock); + mutex_unlock(&cgroup_mutex); + + new_ns = alloc_cgroup_ns(); + if (IS_ERR(new_ns)) { + put_css_set(cset); + return new_ns; + } + + new_ns->user_ns = get_user_ns(user_ns); + new_ns->root_cset = cset; + + return new_ns; +} + +static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns) +{ + return container_of(ns, struct cgroup_namespace, ns); +} + +static int cgroupns_install(struct nsproxy *nsproxy, struct ns_common *ns) +{ + struct cgroup_namespace *cgroup_ns = to_cg_ns(ns); + + if (!ns_capable(current_user_ns(), CAP_SYS_ADMIN) || + !ns_capable(cgroup_ns->user_ns, CAP_SYS_ADMIN)) + return -EPERM; + + /* Don't need to do anything if we are attaching to our own cgroupns. */ + if (cgroup_ns == nsproxy->cgroup_ns) + return 0; + + get_cgroup_ns(cgroup_ns); + put_cgroup_ns(nsproxy->cgroup_ns); + nsproxy->cgroup_ns = cgroup_ns; + + return 0; +} + +static struct ns_common *cgroupns_get(struct task_struct *task) +{ + struct cgroup_namespace *ns = NULL; + struct nsproxy *nsproxy; + + task_lock(task); + nsproxy = task->nsproxy; + if (nsproxy) { + ns = nsproxy->cgroup_ns; + get_cgroup_ns(ns); + } + task_unlock(task); + + return ns ? &ns->ns : NULL; +} + +static void cgroupns_put(struct ns_common *ns) +{ + put_cgroup_ns(to_cg_ns(ns)); +} + +const struct proc_ns_operations cgroupns_operations = { + .name = "cgroup", + .type = CLONE_NEWCGROUP, + .get = cgroupns_get, + .put = cgroupns_put, + .install = cgroupns_install, +}; + +static __init int cgroup_namespaces_init(void) +{ + return 0; +} +subsys_initcall(cgroup_namespaces_init); + #ifdef CONFIG_CGROUP_DEBUG static struct cgroup_subsys_state * debug_css_alloc(struct cgroup_subsys_state *parent_css) diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 9089983..00ab5c2 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -2714,10 +2714,10 @@ int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns, goto out; retval = -ENAMETOOLONG; - rcu_read_lock(); - css = task_css(tsk, cpuset_cgrp_id); - p = cgroup_path(css->cgroup, buf, PATH_MAX); - rcu_read_unlock(); + css = task_get_css(tsk, cpuset_cgrp_id); + p = cgroup_path_ns(css->cgroup, buf, PATH_MAX, + current->nsproxy->cgroup_ns); + css_put(css); if (!p) goto out_free; seq_puts(m, p); diff --git a/kernel/fork.c b/kernel/fork.c index accb722..5b8d1e7 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1892,7 +1892,7 @@ static int check_unshare_flags(unsigned long unshare_flags) if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET| - CLONE_NEWUSER|CLONE_NEWPID)) + CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP)) return -EINVAL; /* * Not implemented, but pretend it works if there is nothing diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c index 49746c8..782102e 100644 --- a/kernel/nsproxy.c +++ b/kernel/nsproxy.c @@ -25,6 +25,7 @@ #include <linux/proc_ns.h> #include <linux/file.h> #include <linux/syscalls.h> +#include <linux/cgroup.h> static struct kmem_cache *nsproxy_cachep; @@ -39,6 +40,9 @@ struct nsproxy init_nsproxy = { #ifdef CONFIG_NET .net_ns = &init_net, #endif +#ifdef CONFIG_CGROUPS + .cgroup_ns = &init_cgroup_ns, +#endif }; static inline struct nsproxy *create_nsproxy(void) @@ -92,6 +96,13 @@ static struct nsproxy *create_new_namespaces(unsigned long flags, goto out_pid; } + new_nsp->cgroup_ns = copy_cgroup_ns(flags, user_ns, + tsk->nsproxy->cgroup_ns); + if (IS_ERR(new_nsp->cgroup_ns)) { + err = PTR_ERR(new_nsp->cgroup_ns); + goto out_cgroup; + } + new_nsp->net_ns = copy_net_ns(flags, user_ns, tsk->nsproxy->net_ns); if (IS_ERR(new_nsp->net_ns)) { err = PTR_ERR(new_nsp->net_ns); @@ -101,6 +112,8 @@ static struct nsproxy *create_new_namespaces(unsigned long flags, return new_nsp; out_net: + put_cgroup_ns(new_nsp->cgroup_ns); +out_cgroup: if (new_nsp->pid_ns_for_children) put_pid_ns(new_nsp->pid_ns_for_children); out_pid: @@ -128,7 +141,8 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk) struct nsproxy *new_ns; if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | - CLONE_NEWPID | CLONE_NEWNET)))) { + CLONE_NEWPID | CLONE_NEWNET | + CLONE_NEWCGROUP)))) { get_nsproxy(old_ns); return 0; } @@ -165,6 +179,7 @@ void free_nsproxy(struct nsproxy *ns) put_ipc_ns(ns->ipc_ns); if (ns->pid_ns_for_children) put_pid_ns(ns->pid_ns_for_children); + put_cgroup_ns(ns->cgroup_ns); put_net(ns->net_ns); kmem_cache_free(nsproxy_cachep, ns); } @@ -180,7 +195,7 @@ int unshare_nsproxy_namespaces(unsigned long unshare_flags, int err = 0; if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | - CLONE_NEWNET | CLONE_NEWPID))) + CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP))) return 0; user_ns = new_cred ? new_cred->user_ns : current_user_ns(); |
