| Message ID | 1444826525-9758-2-git-send-email-l.pawelczyk@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 10/14/2015 5:41 AM, Lukasz Pawelczyk wrote: > This commit implements 3 new LSM hooks that provide the means for LSMs > to embed their own security context within user namespace, effectively > creating some sort of a user_ns related security namespace. > > The first one to take advantage of this mechanism is Smack. > > The hooks has been documented in the in the security.h below. > > Signed-off-by: Lukasz Pawelczyk <l.pawelczyk@samsung.com> > Reviewed-by: Casey Schaufler <casey@schaufler-ca.com> > Acked-by: Paul Moore <paul@paul-moore.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com> > --- > include/linux/lsm_hooks.h | 28 ++++++++++++++++++++++++++++ > include/linux/security.h | 23 +++++++++++++++++++++++ > include/linux/user_namespace.h | 4 ++++ > kernel/user.c | 3 +++ > kernel/user_namespace.c | 18 ++++++++++++++++++ > security/security.c | 28 ++++++++++++++++++++++++++++ > 6 files changed, 104 insertions(+) > > diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h > index ec3a6ba..18c9160 100644 > --- a/include/linux/lsm_hooks.h > +++ b/include/linux/lsm_hooks.h > @@ -1261,6 +1261,23 @@ > * audit_rule_init. > * @rule contains the allocated rule > * > + * @userns_create: > + * Allocates and fills the security part of a new user namespace. > + * @ns points to a newly created user namespace. > + * Returns 0 or an error code. > + * > + * @userns_free: > + * Deallocates the security part of a user namespace. > + * @ns points to a user namespace about to be destroyed. > + * > + * @userns_setns: > + * Run during a setns syscall to add a process to an already existing > + * user namespace. Returning failure here will block the operation > + * requested from userspace (setns() with CLONE_NEWUSER). > + * @nsproxy contains nsproxy to which the user namespace will be assigned. > + * @ns contains user namespace that is to be incorporated to the nsproxy. > + * Returns 0 or an error code. > + * > * @inode_notifysecctx: > * Notify the security module of what the security context of an inode > * should be. Initializes the incore security context managed by the > @@ -1613,6 +1630,12 @@ union security_list_options { > struct audit_context *actx); > void (*audit_rule_free)(void *lsmrule); > #endif /* CONFIG_AUDIT */ > + > +#ifdef CONFIG_USER_NS > + int (*userns_create)(struct user_namespace *ns); > + void (*userns_free)(struct user_namespace *ns); > + int (*userns_setns)(struct nsproxy *nsproxy, struct user_namespace *ns); > +#endif /* CONFIG_USER_NS */ > }; > > struct security_hook_heads { > @@ -1824,6 +1847,11 @@ struct security_hook_heads { > struct list_head audit_rule_match; > struct list_head audit_rule_free; > #endif /* CONFIG_AUDIT */ > +#ifdef CONFIG_USER_NS > + struct list_head userns_create; > + struct list_head userns_free; > + struct list_head userns_setns; > +#endif /* CONFIG_USER_NS */ > }; > > /* > diff --git a/include/linux/security.h b/include/linux/security.h > index 2f4c1f7..91ffba2 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -1584,6 +1584,29 @@ static inline void security_audit_rule_free(void *lsmrule) > #endif /* CONFIG_SECURITY */ > #endif /* CONFIG_AUDIT */ > > +#ifdef CONFIG_USER_NS > +int security_userns_create(struct user_namespace *ns); > +void security_userns_free(struct user_namespace *ns); > +int security_userns_setns(struct nsproxy *nsproxy, struct user_namespace *ns); > + > +#else > + > +static inline int security_userns_create(struct user_namespace *ns) > +{ > + return 0; > +} > + > +static inline void security_userns_free(struct user_namespace *ns) > +{ } > + > +static inline int security_userns_setns(struct nsproxy *nsproxy, > + struct user_namespace *ns) > +{ > + return 0; > +} > + > +#endif /* CONFIG_USER_NS */ > + > #ifdef CONFIG_SECURITYFS > > extern struct dentry *securityfs_create_file(const char *name, umode_t mode, > diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h > index 8297e5b..a9400cc 100644 > --- a/include/linux/user_namespace.h > +++ b/include/linux/user_namespace.h > @@ -39,6 +39,10 @@ struct user_namespace { > struct key *persistent_keyring_register; > struct rw_semaphore persistent_keyring_register_sem; > #endif > + > +#ifdef CONFIG_SECURITY > + void *security; > +#endif > }; > > extern struct user_namespace init_user_ns; > diff --git a/kernel/user.c b/kernel/user.c > index b069ccb..ce5419e 100644 > --- a/kernel/user.c > +++ b/kernel/user.c > @@ -59,6 +59,9 @@ struct user_namespace init_user_ns = { > .persistent_keyring_register_sem = > __RWSEM_INITIALIZER(init_user_ns.persistent_keyring_register_sem), > #endif > +#ifdef CONFIG_SECURITY > + .security = NULL, > +#endif > }; > EXPORT_SYMBOL_GPL(init_user_ns); > > diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c > index 88fefa6..daef188 100644 > --- a/kernel/user_namespace.c > +++ b/kernel/user_namespace.c > @@ -22,6 +22,7 @@ > #include <linux/ctype.h> > #include <linux/projid.h> > #include <linux/fs_struct.h> > +#include <linux/security.h> > > static struct kmem_cache *user_ns_cachep __read_mostly; > static DEFINE_MUTEX(userns_state_mutex); > @@ -109,6 +110,15 @@ int create_user_ns(struct cred *new) > > set_cred_user_ns(new, ns); > > +#ifdef CONFIG_SECURITY > + ret = security_userns_create(ns); > + if (ret) { > + ns_free_inum(&ns->ns); > + kmem_cache_free(user_ns_cachep, ns); > + return ret; > + } > +#endif > + > #ifdef CONFIG_PERSISTENT_KEYRINGS > init_rwsem(&ns->persistent_keyring_register_sem); > #endif > @@ -144,6 +154,9 @@ void free_user_ns(struct user_namespace *ns) > #ifdef CONFIG_PERSISTENT_KEYRINGS > key_put(ns->persistent_keyring_register); > #endif > +#ifdef CONFIG_SECURITY > + security_userns_free(ns); > +#endif > ns_free_inum(&ns->ns); > kmem_cache_free(user_ns_cachep, ns); > ns = parent; > @@ -970,6 +983,7 @@ static int userns_install(struct nsproxy *nsproxy, struct ns_common *ns) > { > struct user_namespace *user_ns = to_user_ns(ns); > struct cred *cred; > + int err; > > /* Don't allow gaining capabilities by reentering > * the same user namespace. > @@ -987,6 +1001,10 @@ static int userns_install(struct nsproxy *nsproxy, struct ns_common *ns) > if (!ns_capable(user_ns, CAP_SYS_ADMIN)) > return -EPERM; > > + err = security_userns_setns(nsproxy, user_ns); > + if (err) > + return err; > + > cred = prepare_creds(); > if (!cred) > return -ENOMEM; > diff --git a/security/security.c b/security/security.c > index 46f405c..e571127 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -25,6 +25,7 @@ > #include <linux/mount.h> > #include <linux/personality.h> > #include <linux/backing-dev.h> > +#include <linux/user_namespace.h> > #include <net/flow.h> > > #define MAX_LSM_EVM_XATTR 2 > @@ -1538,6 +1539,25 @@ int security_audit_rule_match(u32 secid, u32 field, u32 op, void *lsmrule, > } > #endif /* CONFIG_AUDIT */ > > +#ifdef CONFIG_USER_NS > + > +int security_userns_create(struct user_namespace *ns) > +{ > + return call_int_hook(userns_create, 0, ns); > +} > + > +void security_userns_free(struct user_namespace *ns) > +{ > + call_void_hook(userns_free, ns); > +} > + > +int security_userns_setns(struct nsproxy *nsproxy, struct user_namespace *ns) > +{ > + return call_int_hook(userns_setns, 0, nsproxy, ns); > +} > + > +#endif /* CONFIG_USER_NS */ > + > struct security_hook_heads security_hook_heads = { > .binder_set_context_mgr = > LIST_HEAD_INIT(security_hook_heads.binder_set_context_mgr), > @@ -1882,4 +1902,12 @@ struct security_hook_heads security_hook_heads = { > .audit_rule_free = > LIST_HEAD_INIT(security_hook_heads.audit_rule_free), > #endif /* CONFIG_AUDIT */ > +#ifdef CONFIG_USER_NS > + .userns_create = > + LIST_HEAD_INIT(security_hook_heads.userns_create), > + .userns_free = > + LIST_HEAD_INIT(security_hook_heads.userns_free), > + .userns_setns = > + LIST_HEAD_INIT(security_hook_heads.userns_setns), > +#endif /* CONFIG_USER_NS */ > }; 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diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index ec3a6ba..18c9160 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -1261,6 +1261,23 @@ * audit_rule_init. * @rule contains the allocated rule * + * @userns_create: + * Allocates and fills the security part of a new user namespace. + * @ns points to a newly created user namespace. + * Returns 0 or an error code. + * + * @userns_free: + * Deallocates the security part of a user namespace. + * @ns points to a user namespace about to be destroyed. + * + * @userns_setns: + * Run during a setns syscall to add a process to an already existing + * user namespace. Returning failure here will block the operation + * requested from userspace (setns() with CLONE_NEWUSER). + * @nsproxy contains nsproxy to which the user namespace will be assigned. + * @ns contains user namespace that is to be incorporated to the nsproxy. + * Returns 0 or an error code. + * * @inode_notifysecctx: * Notify the security module of what the security context of an inode * should be. Initializes the incore security context managed by the @@ -1613,6 +1630,12 @@ union security_list_options { struct audit_context *actx); void (*audit_rule_free)(void *lsmrule); #endif /* CONFIG_AUDIT */ + +#ifdef CONFIG_USER_NS + int (*userns_create)(struct user_namespace *ns); + void (*userns_free)(struct user_namespace *ns); + int (*userns_setns)(struct nsproxy *nsproxy, struct user_namespace *ns); +#endif /* CONFIG_USER_NS */ }; struct security_hook_heads { @@ -1824,6 +1847,11 @@ struct security_hook_heads { struct list_head audit_rule_match; struct list_head audit_rule_free; #endif /* CONFIG_AUDIT */ +#ifdef CONFIG_USER_NS + struct list_head userns_create; + struct list_head userns_free; + struct list_head userns_setns; +#endif /* CONFIG_USER_NS */ }; /* diff --git a/include/linux/security.h b/include/linux/security.h index 2f4c1f7..91ffba2 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -1584,6 +1584,29 @@ static inline void security_audit_rule_free(void *lsmrule) #endif /* CONFIG_SECURITY */ #endif /* CONFIG_AUDIT */ +#ifdef CONFIG_USER_NS +int security_userns_create(struct user_namespace *ns); +void security_userns_free(struct user_namespace *ns); +int security_userns_setns(struct nsproxy *nsproxy, struct user_namespace *ns); + +#else + +static inline int security_userns_create(struct user_namespace *ns) +{ + return 0; +} + +static inline void security_userns_free(struct user_namespace *ns) +{ } + +static inline int security_userns_setns(struct nsproxy *nsproxy, + struct user_namespace *ns) +{ + return 0; +} + +#endif /* CONFIG_USER_NS */ + #ifdef CONFIG_SECURITYFS extern struct dentry *securityfs_create_file(const char *name, umode_t mode, diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h index 8297e5b..a9400cc 100644 --- a/include/linux/user_namespace.h +++ b/include/linux/user_namespace.h @@ -39,6 +39,10 @@ struct user_namespace { struct key *persistent_keyring_register; struct rw_semaphore persistent_keyring_register_sem; #endif + +#ifdef CONFIG_SECURITY + void *security; +#endif }; extern struct user_namespace init_user_ns; diff --git a/kernel/user.c b/kernel/user.c index b069ccb..ce5419e 100644 --- a/kernel/user.c +++ b/kernel/user.c @@ -59,6 +59,9 @@ struct user_namespace init_user_ns = { .persistent_keyring_register_sem = __RWSEM_INITIALIZER(init_user_ns.persistent_keyring_register_sem), #endif +#ifdef CONFIG_SECURITY + .security = NULL, +#endif }; EXPORT_SYMBOL_GPL(init_user_ns); diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index 88fefa6..daef188 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -22,6 +22,7 @@ #include <linux/ctype.h> #include <linux/projid.h> #include <linux/fs_struct.h> +#include <linux/security.h> static struct kmem_cache *user_ns_cachep __read_mostly; static DEFINE_MUTEX(userns_state_mutex); @@ -109,6 +110,15 @@ int create_user_ns(struct cred *new) set_cred_user_ns(new, ns); +#ifdef CONFIG_SECURITY + ret = security_userns_create(ns); + if (ret) { + ns_free_inum(&ns->ns); + kmem_cache_free(user_ns_cachep, ns); + return ret; + } +#endif + #ifdef CONFIG_PERSISTENT_KEYRINGS init_rwsem(&ns->persistent_keyring_register_sem); #endif @@ -144,6 +154,9 @@ void free_user_ns(struct user_namespace *ns) #ifdef CONFIG_PERSISTENT_KEYRINGS key_put(ns->persistent_keyring_register); #endif +#ifdef CONFIG_SECURITY + security_userns_free(ns); +#endif ns_free_inum(&ns->ns); kmem_cache_free(user_ns_cachep, ns); ns = parent; @@ -970,6 +983,7 @@ static int userns_install(struct nsproxy *nsproxy, struct ns_common *ns) { struct user_namespace *user_ns = to_user_ns(ns); struct cred *cred; + int err; /* Don't allow gaining capabilities by reentering * the same user namespace. @@ -987,6 +1001,10 @@ static int userns_install(struct nsproxy *nsproxy, struct ns_common *ns) if (!ns_capable(user_ns, CAP_SYS_ADMIN)) return -EPERM; + err = security_userns_setns(nsproxy, user_ns); + if (err) + return err; + cred = prepare_creds(); if (!cred) return -ENOMEM; diff --git a/security/security.c b/security/security.c index 46f405c..e571127 100644 --- a/security/security.c +++ b/security/security.c @@ -25,6 +25,7 @@ #include <linux/mount.h> #include <linux/personality.h> #include <linux/backing-dev.h> +#include <linux/user_namespace.h> #include <net/flow.h> #define MAX_LSM_EVM_XATTR 2 @@ -1538,6 +1539,25 @@ int security_audit_rule_match(u32 secid, u32 field, u32 op, void *lsmrule, } #endif /* CONFIG_AUDIT */ +#ifdef CONFIG_USER_NS + +int security_userns_create(struct user_namespace *ns) +{ + return call_int_hook(userns_create, 0, ns); +} + +void security_userns_free(struct user_namespace *ns) +{ + call_void_hook(userns_free, ns); +} + +int security_userns_setns(struct nsproxy *nsproxy, struct user_namespace *ns) +{ + return call_int_hook(userns_setns, 0, nsproxy, ns); +} + +#endif /* CONFIG_USER_NS */ + struct security_hook_heads security_hook_heads = { .binder_set_context_mgr = LIST_HEAD_INIT(security_hook_heads.binder_set_context_mgr), @@ -1882,4 +1902,12 @@ struct security_hook_heads security_hook_heads = { .audit_rule_free = LIST_HEAD_INIT(security_hook_heads.audit_rule_free), #endif /* CONFIG_AUDIT */ +#ifdef CONFIG_USER_NS + .userns_create = + LIST_HEAD_INIT(security_hook_heads.userns_create), + .userns_free = + LIST_HEAD_INIT(security_hook_heads.userns_free), + .userns_setns = + LIST_HEAD_INIT(security_hook_heads.userns_setns), +#endif /* CONFIG_USER_NS */ };