/* * device_cgroup.c - device cgroup subsystem * * Copyright 2007 IBM Corp */ #include <linux/device_cgroup.h>#include <linux/cgroup.h>#include <linux/ctype.h>#include <linux/list.h>#include <linux/uaccess.h>#include <linux/seq_file.h>#include <linux/slab.h>#include <linux/rcupdate.h>#include <linux/mutex.h> #define ACC_MKNOD 1#define ACC_READ 2#define ACC_WRITE 4#define ACC_MASK (ACC_MKNOD | ACC_READ | ACC_WRITE) #define DEV_BLOCK 1#define DEV_CHAR 2#define DEV_ALL 4 /* this represents all devices */ static DEFINE_MUTEX(devcgroup_mutex); /* * exception list locking rules: * hold devcgroup_mutex for update/read. * hold rcu_read_lock() for read. */ struct dev_exception_item { u32 major, minor; short type; short access; struct list_head list; struct rcu_head rcu;}; struct dev_cgroup { struct cgroup_subsys_state css; struct list_head exceptions; enum { DEVCG_DEFAULT_ALLOW, DEVCG_DEFAULT_DENY, } behavior;}; static inline struct dev_cgroup *css_to_devcgroup(struct cgroup_subsys_state *s){ return container_of(s, struct dev_cgroup, css);} static inline struct dev_cgroup *cgroup_to_devcgroup(struct cgroup *cgroup){ return css_to_devcgroup(cgroup_subsys_state(cgroup, devices_subsys_id));} static inline struct dev_cgroup *task_devcgroup(struct task_struct *task){ return css_to_devcgroup(task_subsys_state(task, devices_subsys_id));} struct cgroup_subsys devices_subsys; static int devcgroup_can_attach(struct cgroup *new_cgrp, struct cgroup_taskset *set){ struct task_struct *task = cgroup_taskset_first(set); if (current != task && !capable(CAP_SYS_ADMIN)) return -EPERM; return 0;} /* * called under devcgroup_mutex */static int dev_exceptions_copy(struct list_head *dest, struct list_head *orig){ struct dev_exception_item *ex, *tmp, *new; list_for_each_entry(ex, orig, list) { new = kmemdup(ex, sizeof(*ex), GFP_KERNEL); if (!new) goto free_and_exit; list_add_tail(&new->list, dest); } return 0; free_and_exit: list_for_each_entry_safe(ex, tmp, dest, list) { list_del(&ex->list); kfree(ex); } return -ENOMEM;} /* * called under devcgroup_mutex */static int dev_exception_add(struct dev_cgroup *dev_cgroup, struct dev_exception_item *ex){ struct dev_exception_item *excopy, *walk; excopy = kmemdup(ex, sizeof(*ex), GFP_KERNEL); if (!excopy) return -ENOMEM; list_for_each_entry(walk, &dev_cgroup->exceptions, list) { if (walk->type != ex->type) continue; if (walk->major != ex->major) continue; if (walk->minor != ex->minor) continue; walk->access |= ex->access; kfree(excopy); excopy = NULL; } if (excopy != NULL) list_add_tail_rcu(&excopy->list, &dev_cgroup->exceptions); return 0;} /* * called under devcgroup_mutex */static void dev_exception_rm(struct dev_cgroup *dev_cgroup, struct dev_exception_item *ex){ struct dev_exception_item *walk, *tmp; list_for_each_entry_safe(walk, tmp, &dev_cgroup->exceptions, list) { if (walk->type != ex->type) continue; if (walk->major != ex->major) continue; if (walk->minor != ex->minor) continue; walk->access &= ~ex->access; if (!walk->access) { list_del_rcu(&walk->list); kfree_rcu(walk, rcu); } }} /** * dev_exception_clean - frees all entries of the exception list * @dev_cgroup: dev_cgroup with the exception list to be cleaned * * called under devcgroup_mutex */static void dev_exception_clean(struct dev_cgroup *dev_cgroup){ struct dev_exception_item *ex, *tmp; list_for_each_entry_safe(ex, tmp, &dev_cgroup->exceptions, list) { list_del_rcu(&ex->list); kfree_rcu(ex, rcu); }} /* * called from kernel/cgroup.c with cgroup_lock() held. */static struct cgroup_subsys_state *devcgroup_create(struct cgroup *cgroup){ struct dev_cgroup *dev_cgroup, *parent_dev_cgroup; struct cgroup *parent_cgroup; int ret; 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); } } return &dev_cgroup->css;} static void devcgroup_destroy(struct cgroup *cgroup){ struct dev_cgroup *dev_cgroup; dev_cgroup = cgroup_to_devcgroup(cgroup); dev_exception_clean(dev_cgroup); kfree(dev_cgroup);} #define DEVCG_ALLOW 1#define DEVCG_DENY 2#define DEVCG_LIST 3 #define MAJMINLEN 13#define ACCLEN 4 static void set_access(char *acc, short access){ int idx = 0; memset(acc, 0, ACCLEN); if (access & ACC_READ) acc[idx++] = 'r'; if (access & ACC_WRITE) acc[idx++] = 'w'; if (access & ACC_MKNOD) acc[idx++] = 'm';} static char type_to_char(short type){ if (type == DEV_ALL) return 'a'; if (type == DEV_CHAR) return 'c'; if (type == DEV_BLOCK) return 'b'; return 'X';} static void set_majmin(char *str, unsigned m){ if (m == ~0) strcpy(str, "*"); else sprintf(str, "%u", m);} static int devcgroup_seq_read(struct cgroup *cgroup, struct cftype *cft, struct seq_file *m){ struct dev_cgroup *devcgroup = cgroup_to_devcgroup(cgroup); struct dev_exception_item *ex; char maj[MAJMINLEN], min[MAJMINLEN], acc[ACCLEN]; rcu_read_lock(); /* * To preserve the compatibility: * - Only show the "all devices" when the default policy is to allow * - List the exceptions in case the default policy is to deny * This way, the file remains as a "whitelist of devices" */ if (devcgroup->behavior == DEVCG_DEFAULT_ALLOW) { set_access(acc, ACC_MASK); set_majmin(maj, ~0); set_majmin(min, ~0); seq_printf(m, "%c %s:%s %s\n", type_to_char(DEV_ALL), maj, min, acc); } else { list_for_each_entry_rcu(ex, &devcgroup->exceptions, list) { set_access(acc, ex->access); set_majmin(maj, ex->major); set_majmin(min, ex->minor); seq_printf(m, "%c %s:%s %s\n", type_to_char(ex->type), maj, min, acc); } } rcu_read_unlock(); return 0;} /** * may_access - verifies if a new exception is part of what is allowed * by a dev cgroup based on the default policy + * exceptions. This is used to make sure a child cgroup * won't have more privileges than its parent or to * verify if a certain access is allowed. * @dev_cgroup: dev cgroup to be tested against * @refex: new exception */static int may_access(struct dev_cgroup *dev_cgroup, struct dev_exception_item *refex){ struct dev_exception_item *ex; bool match = false; list_for_each_entry_rcu(ex, &dev_cgroup->exceptions, list) { if ((refex->type & DEV_BLOCK) && !(ex->type & DEV_BLOCK)) continue; if ((refex->type & DEV_CHAR) && !(ex->type & DEV_CHAR)) continue; if (ex->major != ~0 && ex->major != refex->major) continue; if (ex->minor != ~0 && ex->minor != refex->minor) continue; if (refex->access & (~ex->access)) continue; match = true; 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;} /* * parent_has_perm: * when adding a new allow rule to a device exception list, the rule * must be allowed in the parent device */static int parent_has_perm(struct dev_cgroup *childcg, struct dev_exception_item *ex){ struct cgroup *pcg = childcg->css.cgroup->parent; struct dev_cgroup *parent; if (!pcg) return 1; parent = cgroup_to_devcgroup(pcg); return may_access(parent, ex);} /** * may_allow_all - checks if it's possible to change the behavior to * allow based on parent's rules. * @parent: device cgroup's parent * returns: != 0 in case it's allowed, 0 otherwise */static inline int may_allow_all(struct dev_cgroup *parent){ if (!parent) return 1; return parent->behavior == DEVCG_DEFAULT_ALLOW;} /* * Modify the exception list using allow/deny rules. * CAP_SYS_ADMIN is needed for this. It's at least separate from CAP_MKNOD * so we can give a container CAP_MKNOD to let it create devices but not * modify the exception list. * It seems likely we'll want to add a CAP_CONTAINER capability to allow * us to also grant CAP_SYS_ADMIN to containers without giving away the * device exception list controls, but for now we'll stick with CAP_SYS_ADMIN * * Taking rules away is always allowed (given CAP_SYS_ADMIN). Granting * new access is only allowed if you're in the top-level cgroup, or your * parent cgroup has the access you're asking for. */static int devcgroup_update_access(struct dev_cgroup *devcgroup, int filetype, const char *buffer){ const char *b; char temp[12]; /* 11 + 1 characters needed for a u32 */ int count, rc; struct dev_exception_item ex; struct cgroup *p = devcgroup->css.cgroup; struct dev_cgroup *parent = NULL; if (!capable(CAP_SYS_ADMIN)) return -EPERM; if (p->parent) parent = cgroup_to_devcgroup(p->parent); memset(&ex, 0, sizeof(ex)); b = buffer; switch (*b) { case 'a': switch (filetype) { case DEVCG_ALLOW: if (!may_allow_all(parent)) return -EPERM; dev_exception_clean(devcgroup); devcgroup->behavior = DEVCG_DEFAULT_ALLOW; if (!parent) break; rc = dev_exceptions_copy(&devcgroup->exceptions, &parent->exceptions); if (rc) return rc; break; case DEVCG_DENY: dev_exception_clean(devcgroup); devcgroup->behavior = DEVCG_DEFAULT_DENY; break; default: return -EINVAL; } return 0; case 'b': ex.type = DEV_BLOCK; break; case 'c': ex.type = DEV_CHAR; break; default: return -EINVAL; } b++; if (!isspace(*b)) return -EINVAL; b++; if (*b == '*') { ex.major = ~0; b++; } else if (isdigit(*b)) { memset(temp, 0, sizeof(temp)); for (count = 0; count < sizeof(temp) - 1; count++) { temp[count] = *b; b++; if (!isdigit(*b)) break; } rc = kstrtou32(temp, 10, &ex.major); if (rc) return -EINVAL; } else { return -EINVAL; } if (*b != ':') return -EINVAL; b++; /* read minor */ if (*b == '*') { ex.minor = ~0; b++; } else if (isdigit(*b)) { memset(temp, 0, sizeof(temp)); for (count = 0; count < sizeof(temp) - 1; count++) { temp[count] = *b; b++; if (!isdigit(*b)) break; } rc = kstrtou32(temp, 10, &ex.minor); if (rc) return -EINVAL; } else { return -EINVAL; } if (!isspace(*b)) return -EINVAL; for (b++, count = 0; count < 3; count++, b++) { switch (*b) { case 'r': ex.access |= ACC_READ; break; case 'w': ex.access |= ACC_WRITE; break; case 'm': ex.access |= ACC_MKNOD; break; case '\n': case '\0': count = 3; break; default: return -EINVAL; } } switch (filetype) { case DEVCG_ALLOW: if (!parent_has_perm(devcgroup, &ex)) return -EPERM; /* * If the default policy is to allow 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_ALLOW) { dev_exception_rm(devcgroup, &ex);Lines 1–500 of 636. Load more
/* * device_cgroup.c - device cgroup subsystem * * Copyright 2007 IBM Corp */ #include <linux/device_cgroup.h> #include <linux/cgroup.h> #include <linux/ctype.h> #include <linux/list.h> #include <linux/uaccess.h> #include <linux/seq_file.h> #include <linux/slab.h> #include <linux/rcupdate.h> #include <linux/mutex.h> #define ACC_MKNOD 1 #define ACC_READ 2 #define ACC_WRITE 4 #define ACC_MASK (ACC_MKNOD | ACC_READ | ACC_WRITE) #define DEV_BLOCK 1 #define DEV_CHAR 2 #define DEV_ALL 4 /* this represents all devices */ static DEFINE_MUTEX(devcgroup_mutex); /* * exception list locking rules: * hold devcgroup_mutex for update/read. * hold rcu_read_lock() for read. */ struct dev_exception_item { u32 major, minor; short type; short access; struct list_head list; struct rcu_head rcu; }; struct dev_cgroup { struct cgroup_subsys_state css; struct list_head exceptions; enum { DEVCG_DEFAULT_ALLOW, DEVCG_DEFAULT_DENY, } behavior; }; static inline struct dev_cgroup *css_to_devcgroup(struct cgroup_subsys_state *s) { return container_of(s, struct dev_cgroup, css); } static inline struct dev_cgroup *cgroup_to_devcgroup(struct cgroup *cgroup) { return css_to_devcgroup(cgroup_subsys_state(cgroup, devices_subsys_id)); } static inline struct dev_cgroup *task_devcgroup(struct task_struct *task) { return css_to_devcgroup(task_subsys_state(task, devices_subsys_id)); } struct cgroup_subsys devices_subsys; static int devcgroup_can_attach(struct cgroup *new_cgrp, struct cgroup_taskset *set) { struct task_struct *task = cgroup_taskset_first(set); if (current != task && !capable(CAP_SYS_ADMIN)) return -EPERM; return 0; } /* * called under devcgroup_mutex */ static int dev_exceptions_copy(struct list_head *dest, struct list_head *orig) { struct dev_exception_item *ex, *tmp, *new; list_for_each_entry(ex, orig, list) { new = kmemdup(ex, sizeof(*ex), GFP_KERNEL); if (!new) goto free_and_exit; list_add_tail(&new->list, dest); } return 0; free_and_exit: list_for_each_entry_safe(ex, tmp, dest, list) { list_del(&ex->list); kfree(ex); } return -ENOMEM; } /* * called under devcgroup_mutex */ static int dev_exception_add(struct dev_cgroup *dev_cgroup, struct dev_exception_item *ex) { struct dev_exception_item *excopy, *walk; excopy = kmemdup(ex, sizeof(*ex), GFP_KERNEL); if (!excopy) return -ENOMEM; list_for_each_entry(walk, &dev_cgroup->exceptions, list) { if (walk->type != ex->type) continue; if (walk->major != ex->major) continue; if (walk->minor != ex->minor) continue; walk->access |= ex->access; kfree(excopy); excopy = NULL; } if (excopy != NULL) list_add_tail_rcu(&excopy->list, &dev_cgroup->exceptions); return 0; } /* * called under devcgroup_mutex */ static void dev_exception_rm(struct dev_cgroup *dev_cgroup, struct dev_exception_item *ex) { struct dev_exception_item *walk, *tmp; list_for_each_entry_safe(walk, tmp, &dev_cgroup->exceptions, list) { if (walk->type != ex->type) continue; if (walk->major != ex->major) continue; if (walk->minor != ex->minor) continue; walk->access &= ~ex->access; if (!walk->access) { list_del_rcu(&walk->list); kfree_rcu(walk, rcu); } } } /** * dev_exception_clean - frees all entries of the exception list * @dev_cgroup: dev_cgroup with the exception list to be cleaned * * called under devcgroup_mutex */ static void dev_exception_clean(struct dev_cgroup *dev_cgroup) { struct dev_exception_item *ex, *tmp; list_for_each_entry_safe(ex, tmp, &dev_cgroup->exceptions, list) { list_del_rcu(&ex->list); kfree_rcu(ex, rcu); } } /* * called from kernel/cgroup.c with cgroup_lock() held. */ static struct cgroup_subsys_state *devcgroup_create(struct cgroup *cgroup) { struct dev_cgroup *dev_cgroup, *parent_dev_cgroup; struct cgroup *parent_cgroup; int ret; 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); } } return &dev_cgroup->css; } static void devcgroup_destroy(struct cgroup *cgroup) { struct dev_cgroup *dev_cgroup; dev_cgroup = cgroup_to_devcgroup(cgroup); dev_exception_clean(dev_cgroup); kfree(dev_cgroup); } #define DEVCG_ALLOW 1 #define DEVCG_DENY 2 #define DEVCG_LIST 3 #define MAJMINLEN 13 #define ACCLEN 4 static void set_access(char *acc, short access) { int idx = 0; memset(acc, 0, ACCLEN); if (access & ACC_READ) acc[idx++] = 'r'; if (access & ACC_WRITE) acc[idx++] = 'w'; if (access & ACC_MKNOD) acc[idx++] = 'm'; } static char type_to_char(short type) { if (type == DEV_ALL) return 'a'; if (type == DEV_CHAR) return 'c'; if (type == DEV_BLOCK) return 'b'; return 'X'; } static void set_majmin(char *str, unsigned m) { if (m == ~0) strcpy(str, "*"); else sprintf(str, "%u", m); } static int devcgroup_seq_read(struct cgroup *cgroup, struct cftype *cft, struct seq_file *m) { struct dev_cgroup *devcgroup = cgroup_to_devcgroup(cgroup); struct dev_exception_item *ex; char maj[MAJMINLEN], min[MAJMINLEN], acc[ACCLEN]; rcu_read_lock(); /* * To preserve the compatibility: * - Only show the "all devices" when the default policy is to allow * - List the exceptions in case the default policy is to deny * This way, the file remains as a "whitelist of devices" */ if (devcgroup->behavior == DEVCG_DEFAULT_ALLOW) { set_access(acc, ACC_MASK); set_majmin(maj, ~0); set_majmin(min, ~0); seq_printf(m, "%c %s:%s %s\n", type_to_char(DEV_ALL), maj, min, acc); } else { list_for_each_entry_rcu(ex, &devcgroup->exceptions, list) { set_access(acc, ex->access); set_majmin(maj, ex->major); set_majmin(min, ex->minor); seq_printf(m, "%c %s:%s %s\n", type_to_char(ex->type), maj, min, acc); } } rcu_read_unlock(); return 0; } /** * may_access - verifies if a new exception is part of what is allowed * by a dev cgroup based on the default policy + * exceptions. This is used to make sure a child cgroup * won't have more privileges than its parent or to * verify if a certain access is allowed. * @dev_cgroup: dev cgroup to be tested against * @refex: new exception */ static int may_access(struct dev_cgroup *dev_cgroup, struct dev_exception_item *refex) { struct dev_exception_item *ex; bool match = false; list_for_each_entry_rcu(ex, &dev_cgroup->exceptions, list) { if ((refex->type & DEV_BLOCK) && !(ex->type & DEV_BLOCK)) continue; if ((refex->type & DEV_CHAR) && !(ex->type & DEV_CHAR)) continue; if (ex->major != ~0 && ex->major != refex->major) continue; if (ex->minor != ~0 && ex->minor != refex->minor) continue; if (refex->access & (~ex->access)) continue; match = true; 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; } /* * parent_has_perm: * when adding a new allow rule to a device exception list, the rule * must be allowed in the parent device */ static int parent_has_perm(struct dev_cgroup *childcg, struct dev_exception_item *ex) { struct cgroup *pcg = childcg->css.cgroup->parent; struct dev_cgroup *parent; if (!pcg) return 1; parent = cgroup_to_devcgroup(pcg); return may_access(parent, ex); } /** * may_allow_all - checks if it's possible to change the behavior to * allow based on parent's rules. * @parent: device cgroup's parent * returns: != 0 in case it's allowed, 0 otherwise */ static inline int may_allow_all(struct dev_cgroup *parent) { if (!parent) return 1; return parent->behavior == DEVCG_DEFAULT_ALLOW; } /* * Modify the exception list using allow/deny rules. * CAP_SYS_ADMIN is needed for this. It's at least separate from CAP_MKNOD * so we can give a container CAP_MKNOD to let it create devices but not * modify the exception list. * It seems likely we'll want to add a CAP_CONTAINER capability to allow * us to also grant CAP_SYS_ADMIN to containers without giving away the * device exception list controls, but for now we'll stick with CAP_SYS_ADMIN * * Taking rules away is always allowed (given CAP_SYS_ADMIN). Granting * new access is only allowed if you're in the top-level cgroup, or your * parent cgroup has the access you're asking for. */ static int devcgroup_update_access(struct dev_cgroup *devcgroup, int filetype, const char *buffer) { const char *b; char temp[12]; /* 11 + 1 characters needed for a u32 */ int count, rc; struct dev_exception_item ex; struct cgroup *p = devcgroup->css.cgroup; struct dev_cgroup *parent = NULL; if (!capable(CAP_SYS_ADMIN)) return -EPERM; if (p->parent) parent = cgroup_to_devcgroup(p->parent); memset(&ex, 0, sizeof(ex)); b = buffer; switch (*b) { case 'a': switch (filetype) { case DEVCG_ALLOW: if (!may_allow_all(parent)) return -EPERM; dev_exception_clean(devcgroup); devcgroup->behavior = DEVCG_DEFAULT_ALLOW; if (!parent) break; rc = dev_exceptions_copy(&devcgroup->exceptions, &parent->exceptions); if (rc) return rc; break; case DEVCG_DENY: dev_exception_clean(devcgroup); devcgroup->behavior = DEVCG_DEFAULT_DENY; break; default: return -EINVAL; } return 0; case 'b': ex.type = DEV_BLOCK; break; case 'c': ex.type = DEV_CHAR; break; default: return -EINVAL; } b++; if (!isspace(*b)) return -EINVAL; b++; if (*b == '*') { ex.major = ~0; b++; } else if (isdigit(*b)) { memset(temp, 0, sizeof(temp)); for (count = 0; count < sizeof(temp) - 1; count++) { temp[count] = *b; b++; if (!isdigit(*b)) break; } rc = kstrtou32(temp, 10, &ex.major); if (rc) return -EINVAL; } else { return -EINVAL; } if (*b != ':') return -EINVAL; b++; /* read minor */ if (*b == '*') { ex.minor = ~0; b++; } else if (isdigit(*b)) { memset(temp, 0, sizeof(temp)); for (count = 0; count < sizeof(temp) - 1; count++) { temp[count] = *b; b++; if (!isdigit(*b)) break; } rc = kstrtou32(temp, 10, &ex.minor); if (rc) return -EINVAL; } else { return -EINVAL; } if (!isspace(*b)) return -EINVAL; for (b++, count = 0; count < 3; count++, b++) { switch (*b) { case 'r': ex.access |= ACC_READ; break; case 'w': ex.access |= ACC_WRITE; break; case 'm': ex.access |= ACC_MKNOD; break; case '\n': case '\0': count = 3; break; default: return -EINVAL; } } switch (filetype) { case DEVCG_ALLOW: if (!parent_has_perm(devcgroup, &ex)) return -EPERM; /* * If the default policy is to allow 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_ALLOW) { dev_exception_rm(devcgroup, &ex);