10 files changed, 267 insertions, 0 deletions

diff --git a/security/capability.c b/security/capability.c
index 06400cf07757..93a2ffe65905 100644
--- a/security/capability.c
+++ b/security/capability.c
@@ -373,6 +373,11 @@ static int cap_task_create(unsigned long clone_flags)
         return 0;
 }
 
+static int cap_cred_alloc_blank(struct cred *cred, gfp_t gfp)
+{
+        return 0;
+}
+
 static void cap_cred_free(struct cred *cred)
 {
 }
@@ -386,6 +391,10 @@ static void cap_cred_commit(struct cred *new, const struct cred *old)
 {
 }
 
+static void cap_cred_transfer(struct cred *new, const struct cred *old)
+{
+}
+
 static int cap_kernel_act_as(struct cred *new, u32 secid)
 {
         return 0;
@@ -836,6 +845,13 @@ static int cap_key_getsecurity(struct key *key, char **_buffer)
         return 0;
 }
 
+static int cap_key_session_to_parent(const struct cred *cred,
+                                     const struct cred *parent_cred,
+                                     struct key *key)
+{
+        return 0;
+}
+
 #endif /* CONFIG_KEYS */
 
 #ifdef CONFIG_AUDIT
@@ -961,9 +977,11 @@ void security_fixup_ops(struct security_operations *ops)
         set_to_cap_if_null(ops, file_receive);
         set_to_cap_if_null(ops, dentry_open);
         set_to_cap_if_null(ops, task_create);
+        set_to_cap_if_null(ops, cred_alloc_blank);
         set_to_cap_if_null(ops, cred_free);
         set_to_cap_if_null(ops, cred_prepare);
         set_to_cap_if_null(ops, cred_commit);
+        set_to_cap_if_null(ops, cred_transfer);
         set_to_cap_if_null(ops, kernel_act_as);
         set_to_cap_if_null(ops, kernel_create_files_as);
         set_to_cap_if_null(ops, kernel_module_request);
@@ -1063,6 +1081,7 @@ void security_fixup_ops(struct security_operations *ops)
         set_to_cap_if_null(ops, key_free);
         set_to_cap_if_null(ops, key_permission);
         set_to_cap_if_null(ops, key_getsecurity);
+        set_to_cap_if_null(ops, key_session_to_parent);
 #endif  /* CONFIG_KEYS */
 #ifdef CONFIG_AUDIT
         set_to_cap_if_null(ops, audit_rule_init);
diff --git a/security/keys/compat.c b/security/keys/compat.c
index c766c68a63bc..792c0a611a6d 100644
--- a/security/keys/compat.c
+++ b/security/keys/compat.c
@@ -82,6 +82,9 @@ asmlinkage long compat_sys_keyctl(u32 option,
         case KEYCTL_GET_SECURITY:
                 return keyctl_get_security(arg2, compat_ptr(arg3), arg4);
 
+        case KEYCTL_SESSION_TO_PARENT:
+                return keyctl_session_to_parent();
+
         default:
                 return -EOPNOTSUPP;
         }
diff --git a/security/keys/gc.c b/security/keys/gc.c
index 44adc325e15c..1e616aef55fd 100644
--- a/security/keys/gc.c
+++ b/security/keys/gc.c
@@ -65,6 +65,7 @@ static void key_gc_timer_func(unsigned long data)
  * - return true if we altered the keyring
  */
 static bool key_gc_keyring(struct key *keyring, time_t limit)
+        __releases(key_serial_lock)
 {
         struct keyring_list *klist;
         struct key *key;
diff --git a/security/keys/internal.h b/security/keys/internal.h
index fb830514c337..24ba0307b7ad 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -201,6 +201,7 @@ extern long keyctl_set_timeout(key_serial_t, unsigned);
 extern long keyctl_assume_authority(key_serial_t);
 extern long keyctl_get_security(key_serial_t keyid, char __user *buffer,
                                 size_t buflen);
+extern long keyctl_session_to_parent(void);
 
 /*
  * debugging key validation
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 736d7800f97f..74c968524592 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -1228,6 +1228,105 @@ long keyctl_get_security(key_serial_t keyid,
         return ret;
 }
 
+/*
+ * attempt to install the calling process's session keyring on the process's
+ * parent process
+ * - the keyring must exist and must grant us LINK permission
+ * - implements keyctl(KEYCTL_SESSION_TO_PARENT)
+ */
+long keyctl_session_to_parent(void)
+{
+        struct task_struct *me, *parent;
+        const struct cred *mycred, *pcred;
+        struct cred *cred, *oldcred;
+        key_ref_t keyring_r;
+        int ret;
+
+        keyring_r = lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_LINK);
+        if (IS_ERR(keyring_r))
+                return PTR_ERR(keyring_r);
+
+        /* our parent is going to need a new cred struct, a new tgcred struct
+         * and new security data, so we allocate them here to prevent ENOMEM in
+         * our parent */
+        ret = -ENOMEM;
+        cred = cred_alloc_blank();
+        if (!cred)
+                goto error_keyring;
+
+        cred->tgcred->session_keyring = key_ref_to_ptr(keyring_r);
+        keyring_r = NULL;
+
+        me = current;
+        write_lock_irq(&tasklist_lock);
+
+        parent = me->real_parent;
+        ret = -EPERM;
+
+        /* the parent mustn't be init and mustn't be a kernel thread */
+        if (parent->pid <= 1 || !parent->mm)
+                goto not_permitted;
+
+        /* the parent must be single threaded */
+        if (atomic_read(&parent->signal->count) != 1)
+                goto not_permitted;
+
+        /* the parent and the child must have different session keyrings or
+         * there's no point */
+        mycred = current_cred();
+        pcred = __task_cred(parent);
+        if (mycred == pcred ||
+            mycred->tgcred->session_keyring == pcred->tgcred->session_keyring)
+                goto already_same;
+
+        /* the parent must have the same effective ownership and mustn't be
+         * SUID/SGID */
+        if (pcred-> uid != mycred->euid ||
+            pcred->euid != mycred->euid ||
+            pcred->suid != mycred->euid ||
+            pcred-> gid != mycred->egid ||
+            pcred->egid != mycred->egid ||
+            pcred->sgid != mycred->egid)
+                goto not_permitted;
+
+        /* the keyrings must have the same UID */
+        if (pcred ->tgcred->session_keyring->uid != mycred->euid ||
+            mycred->tgcred->session_keyring->uid != mycred->euid)
+                goto not_permitted;
+
+        /* the LSM must permit the replacement of the parent's keyring with the
+         * keyring from this process */
+        ret = security_key_session_to_parent(mycred, pcred,
+                                             key_ref_to_ptr(keyring_r));
+        if (ret < 0)
+                goto not_permitted;
+
+        /* if there's an already pending keyring replacement, then we replace
+         * that */
+        oldcred = parent->replacement_session_keyring;
+
+        /* the replacement session keyring is applied just prior to userspace
+         * restarting */
+        parent->replacement_session_keyring = cred;
+        cred = NULL;
+        set_ti_thread_flag(task_thread_info(parent), TIF_NOTIFY_RESUME);
+
+        write_unlock_irq(&tasklist_lock);
+        if (oldcred)
+                put_cred(oldcred);
+        return 0;
+
+already_same:
+        ret = 0;
+not_permitted:
+        put_cred(cred);
+        return ret;
+
+error_keyring:
+        key_ref_put(keyring_r);
+        return ret;
+}
+
 /*****************************************************************************/
 /*
  * the key control system call
@@ -1313,6 +1412,9 @@ SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
                                            (char __user *) arg3,
                                            (size_t) arg4);
 
+        case KEYCTL_SESSION_TO_PARENT:
+                return keyctl_session_to_parent();
+
         default:
                 return -EOPNOTSUPP;
         }
diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index 4739cfbb41b7..5c23afb31ece 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -17,6 +17,7 @@
 #include <linux/fs.h>
 #include <linux/err.h>
 #include <linux/mutex.h>
+#include <linux/security.h>
 #include <linux/user_namespace.h>
 #include <asm/uaccess.h>
 #include "internal.h"
@@ -768,3 +769,51 @@ error:
         abort_creds(new);
         return ret;
 }
+
+/*
+ * Replace a process's session keyring when that process resumes userspace on
+ * behalf of one of its children
+ */
+void key_replace_session_keyring(void)
+{
+        const struct cred *old;
+        struct cred *new;
+
+        if (!current->replacement_session_keyring)
+                return;
+
+        write_lock_irq(&tasklist_lock);
+        new = current->replacement_session_keyring;
+        current->replacement_session_keyring = NULL;
+        write_unlock_irq(&tasklist_lock);
+
+        if (!new)
+                return;
+
+        old = current_cred();
+        new->  uid      = old->  uid;
+        new-> euid      = old-> euid;
+        new-> suid      = old-> suid;
+        new->fsuid      = old->fsuid;
+        new->  gid      = old->  gid;
+        new-> egid      = old-> egid;
+        new-> sgid      = old-> sgid;
+        new->fsgid      = old->fsgid;
+        new->user       = get_uid(old->user);
+        new->group_info = get_group_info(old->group_info);
+
+        new->securebits = old->securebits;
+        new->cap_inheritable    = old->cap_inheritable;
+        new->cap_permitted      = old->cap_permitted;
+        new->cap_effective      = old->cap_effective;
+        new->cap_bset           = old->cap_bset;
+
+        new->jit_keyring        = old->jit_keyring;
+        new->thread_keyring     = key_get(old->thread_keyring);
+        new->tgcred->tgid       = old->tgcred->tgid;
+        new->tgcred->process_keyring = key_get(old->tgcred->process_keyring);
+
+        security_transfer_creds(new, old);
+
+        commit_creds(new);
+}
diff --git a/security/security.c b/security/security.c
index f88eaf6b14cc..d8b727637f02 100644
--- a/security/security.c
+++ b/security/security.c
@@ -684,6 +684,11 @@ int security_task_create(unsigned long clone_flags)
         return security_ops->task_create(clone_flags);
 }
 
+int security_cred_alloc_blank(struct cred *cred, gfp_t gfp)
+{
+        return security_ops->cred_alloc_blank(cred, gfp);
+}
+
 void security_cred_free(struct cred *cred)
 {
         security_ops->cred_free(cred);
@@ -699,6 +704,11 @@ void security_commit_creds(struct cred *new, const struct cred *old)
         security_ops->cred_commit(new, old);
 }
 
+void security_transfer_creds(struct cred *new, const struct cred *old)
+{
+        security_ops->cred_transfer(new, old);
+}
+
 int security_kernel_act_as(struct cred *new, u32 secid)
 {
         return security_ops->kernel_act_as(new, secid);
@@ -1241,6 +1251,13 @@ int security_key_getsecurity(struct key *key, char **_buffer)
         return security_ops->key_getsecurity(key, _buffer);
 }
 
+int security_key_session_to_parent(const struct cred *cred,
+                                   const struct cred *parent_cred,
+                                   struct key *key)
+{
+        return security_ops->key_session_to_parent(cred, parent_cred, key);
+}
+
 #endif  /* CONFIG_KEYS */
 
 #ifdef CONFIG_AUDIT
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index c3bb31ecc5aa..134a9c0d2004 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3233,6 +3233,21 @@ static int selinux_task_create(unsigned long clone_flags)
 }
 
 /*
+ * allocate the SELinux part of blank credentials
+ */
+static int selinux_cred_alloc_blank(struct cred *cred, gfp_t gfp)
+{
+        struct task_security_struct *tsec;
+
+        tsec = kzalloc(sizeof(struct task_security_struct), gfp);
+        if (!tsec)
+                return -ENOMEM;
+
+        cred->security = tsec;
+        return 0;
+}
+
+/*
  * detach and free the LSM part of a set of credentials
  */
 static void selinux_cred_free(struct cred *cred)
@@ -3264,6 +3279,17 @@ static int selinux_cred_prepare(struct cred *new, const struct cred *old,
 }
 
 /*
+ * transfer the SELinux data to a blank set of creds
+ */
+static void selinux_cred_transfer(struct cred *new, const struct cred *old)
+{
+        const struct task_security_struct *old_tsec = old->security;
+        struct task_security_struct *tsec = new->security;
+
+        *tsec = *old_tsec;
+}
+
+/*
  * set the security data for a kernel service
  * - all the creation contexts are set to unlabelled
  */
@@ -5469,8 +5495,10 @@ static struct security_operations selinux_ops = {
         .dentry_open =                  selinux_dentry_open,
 
         .task_create =                  selinux_task_create,
+        .cred_alloc_blank =             selinux_cred_alloc_blank,
         .cred_free =                    selinux_cred_free,
         .cred_prepare =                 selinux_cred_prepare,
+        .cred_transfer =                selinux_cred_transfer,
         .kernel_act_as =                selinux_kernel_act_as,
         .kernel_create_files_as =       selinux_kernel_create_files_as,
         .kernel_module_request =        selinux_kernel_module_request,
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index c243a2b25832..969f5fee1906 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -1080,6 +1080,22 @@ static int smack_file_receive(struct file *file)
  */
 
 /**
+ * smack_cred_alloc_blank - "allocate" blank task-level security credentials
+ * @new: the new credentials
+ * @gfp: the atomicity of any memory allocations
+ *
+ * Prepare a blank set of credentials for modification.  This must allocate all
+ * the memory the LSM module might require such that cred_transfer() can
+ * complete without error.
+ */
+static int smack_cred_alloc_blank(struct cred *cred, gfp_t gfp)
+{
+        cred->security = NULL;
+        return 0;
+}
+
+
+/**
  * smack_cred_free - "free" task-level security credentials
  * @cred: the credentials in question
  *
@@ -1117,6 +1133,18 @@ static void smack_cred_commit(struct cred *new, const struct cred *old)
 }
 
 /**
+ * smack_cred_transfer - Transfer the old credentials to the new credentials
+ * @new: the new credentials
+ * @old: the original credentials
+ *
+ * Fill in a set of blank credentials from another set of credentials.
+ */
+static void smack_cred_transfer(struct cred *new, const struct cred *old)
+{
+        new->security = old->security;
+}
+
+/**
  * smack_kernel_act_as - Set the subjective context in a set of credentials
  * @new: points to the set of credentials to be modified.
  * @secid: specifies the security ID to be set
@@ -3073,9 +3101,11 @@ struct security_operations smack_ops = {
         .file_send_sigiotask =          smack_file_send_sigiotask,
         .file_receive =                 smack_file_receive,
 
+        .cred_alloc_blank =             smack_cred_alloc_blank,
         .cred_free =                    smack_cred_free,
         .cred_prepare =                 smack_cred_prepare,
         .cred_commit =                  smack_cred_commit,
+        .cred_transfer =                smack_cred_transfer,
         .kernel_act_as =                smack_kernel_act_as,
         .kernel_create_files_as =       smack_kernel_create_files_as,
         .task_setpgid =                 smack_task_setpgid,
diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c
index 35a13e7915e4..9548a0984cc4 100644
--- a/security/tomoyo/tomoyo.c
+++ b/security/tomoyo/tomoyo.c
@@ -14,6 +14,12 @@
 #include "tomoyo.h"
 #include "realpath.h"
 
+static int tomoyo_cred_alloc_blank(struct cred *new, gfp_t gfp)
+{
+        new->security = NULL;
+        return 0;
+}
+
 static int tomoyo_cred_prepare(struct cred *new, const struct cred *old,
                                gfp_t gfp)
 {
@@ -25,6 +31,15 @@ static int tomoyo_cred_prepare(struct cred *new, const struct cred *old,
         return 0;
 }
 
+static void tomoyo_cred_transfer(struct cred *new, const struct cred *old)
+{
+        /*
+         * Since "struct tomoyo_domain_info *" is a sharable pointer,
+         * we don't need to duplicate.
+         */
+        new->security = old->security;
+}
+
 static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
 {
         int rc;
@@ -262,7 +277,9 @@ static int tomoyo_dentry_open(struct file *f, const struct cred *cred)
  */
 static struct security_operations tomoyo_security_ops = {
         .name                = "tomoyo",
+        .cred_alloc_blank    = tomoyo_cred_alloc_blank,
         .cred_prepare        = tomoyo_cred_prepare,
+        .cred_transfer       = tomoyo_cred_transfer,
         .bprm_set_creds      = tomoyo_bprm_set_creds,
         .bprm_check_security = tomoyo_bprm_check_security,
 #ifdef CONFIG_SYSCTL