CRED: Wrap task credential accesses in the core kernel

Wrap access to task credentials so that they can be separated more easily from
the task_struct during the introduction of COW creds.

Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id().

Change some task->e?[ug]id to task_e?[ug]id().  In some places it makes more
sense to use RCU directly rather than a convenient wrapper; these will be
addressed by later patches.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-audit@redhat.com
Cc: containers@lists.linux-foundation.org
Cc: linux-mm@kvack.org
Signed-off-by: James Morris <jmorris@namei.org>

12 files changed, 58 insertions, 44 deletions

diff --git a/kernel/acct.c b/kernel/acct.c
index f6006a60df5d..d57b7cbb98b6 100644
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -530,15 +530,14 @@ static void do_acct_process(struct bsd_acct_struct *acct,
         do_div(elapsed, AHZ);
         ac.ac_btime = get_seconds() - elapsed;
         /* we really need to bite the bullet and change layout */
-        ac.ac_uid = current->uid;
-        ac.ac_gid = current->gid;
+        current_uid_gid(&ac.ac_uid, &ac.ac_gid);
 #if ACCT_VERSION==2
         ac.ac_ahz = AHZ;
 #endif
 #if ACCT_VERSION==1 || ACCT_VERSION==2
         /* backward-compatible 16 bit fields */
-        ac.ac_uid16 = current->uid;
-        ac.ac_gid16 = current->gid;
+        ac.ac_uid16 = ac.ac_uid;
+        ac.ac_gid16 = ac.ac_gid;
 #endif
 #if ACCT_VERSION==3
         ac.ac_pid = task_tgid_nr_ns(current, ns);
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index cef34235b362..9c7e47ae4576 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -2628,7 +2628,8 @@ void audit_core_dumps(long signr)
 {
         struct audit_buffer *ab;
         u32 sid;
-        uid_t auid = audit_get_loginuid(current);
+        uid_t auid = audit_get_loginuid(current), uid;
+        gid_t gid;
         unsigned int sessionid = audit_get_sessionid(current);
 
         if (!audit_enabled)
@@ -2638,8 +2639,9 @@ void audit_core_dumps(long signr)
                 return;
 
         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_ANOM_ABEND);
+        current_uid_gid(&uid, &gid);
         audit_log_format(ab, "auid=%u uid=%u gid=%u ses=%u",
-                        auid, current->uid, current->gid, sessionid);
+                         auid, uid, gid, sessionid);
         security_task_getsecid(current, &sid);
         if (sid) {
                 char *ctx = NULL;
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 35eebd5510c2..78f9b310c4f3 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -571,8 +571,8 @@ static struct inode *cgroup_new_inode(mode_t mode, struct super_block *sb)
 
         if (inode) {
                 inode->i_mode = mode;
-                inode->i_uid = current->fsuid;
-                inode->i_gid = current->fsgid;
+                inode->i_uid = current_fsuid();
+                inode->i_gid = current_fsgid();
                 inode->i_blocks = 0;
                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
                 inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info;
@@ -1279,6 +1279,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
 static int attach_task_by_pid(struct cgroup *cgrp, u64 pid)
 {
         struct task_struct *tsk;
+        uid_t euid;
         int ret;
 
         if (pid) {
@@ -1291,8 +1292,8 @@ static int attach_task_by_pid(struct cgroup *cgrp, u64 pid)
                 get_task_struct(tsk);
                 rcu_read_unlock();
 
-                if ((current->euid) && (current->euid != tsk->uid)
-                    && (current->euid != tsk->suid)) {
+                euid = current_euid();
+                if (euid && euid != tsk->uid && euid != tsk->suid) {
                         put_task_struct(tsk);
                         return -EACCES;
                 }
diff --git a/kernel/futex.c b/kernel/futex.c
index 8af10027514b..e06962132aaf 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -439,10 +439,11 @@ static void free_pi_state(struct futex_pi_state *pi_state)
 static struct task_struct * futex_find_get_task(pid_t pid)
 {
         struct task_struct *p;
+        uid_t euid = current_euid();
 
         rcu_read_lock();
         p = find_task_by_vpid(pid);
-        if (!p || ((current->euid != p->euid) && (current->euid != p->uid)))
+        if (!p || (euid != p->euid && euid != p->uid))
                 p = ERR_PTR(-ESRCH);
         else
                 get_task_struct(p);
@@ -1829,6 +1830,7 @@ sys_get_robust_list(int pid, struct robust_list_head __user * __user *head_ptr,
 {
         struct robust_list_head __user *head;
         unsigned long ret;
+        uid_t euid = current_euid();
 
         if (!futex_cmpxchg_enabled)
                 return -ENOSYS;
@@ -1844,8 +1846,8 @@ sys_get_robust_list(int pid, struct robust_list_head __user * __user *head_ptr,
                 if (!p)
                         goto err_unlock;
                 ret = -EPERM;
-                if ((current->euid != p->euid) && (current->euid != p->uid) &&
-                                !capable(CAP_SYS_PTRACE))
+                if (euid != p->euid && euid != p->uid &&
+                    !capable(CAP_SYS_PTRACE))
                         goto err_unlock;
                 head = p->robust_list;
                 rcu_read_unlock();
diff --git a/kernel/futex_compat.c b/kernel/futex_compat.c
index 04ac3a9e42cf..3254d4e41e88 100644
--- a/kernel/futex_compat.c
+++ b/kernel/futex_compat.c
@@ -135,6 +135,7 @@ compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr,
 {
         struct compat_robust_list_head __user *head;
         unsigned long ret;
+        uid_t euid = current_euid();
 
         if (!futex_cmpxchg_enabled)
                 return -ENOSYS;
@@ -150,7 +151,7 @@ compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr,
                 if (!p)
                         goto err_unlock;
                 ret = -EPERM;
-                if ((current->euid != p->euid) && (current->euid != p->uid) &&
+                if (euid != p->euid && euid != p->uid &&
                                 !capable(CAP_SYS_PTRACE))
                         goto err_unlock;
                 head = p->compat_robust_list;
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 1e68e4c39e2c..937f6b5b2008 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -123,16 +123,19 @@ int __ptrace_may_access(struct task_struct *task, unsigned int mode)
          * because setting up the necessary parent/child relationship
          * or halting the specified task is impossible.
          */
+        uid_t uid;
+        gid_t gid;
         int dumpable = 0;
         /* Don't let security modules deny introspection */
         if (task == current)
                 return 0;
-        if (((current->uid != task->euid) ||
-             (current->uid != task->suid) ||
-             (current->uid != task->uid) ||
-             (current->gid != task->egid) ||
-             (current->gid != task->sgid) ||
-             (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE))
+        current_uid_gid(&uid, &gid);
+        if ((uid != task->euid ||
+             uid != task->suid ||
+             uid != task->uid  ||
+             gid != task->egid ||
+             gid != task->sgid ||
+             gid != task->gid) && !capable(CAP_SYS_PTRACE))
                 return -EPERM;
         smp_rmb();
         if (task->mm)
diff --git a/kernel/sched.c b/kernel/sched.c
index e8819bc6f462..c3b8b1fcde0d 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5128,6 +5128,7 @@ static int __sched_setscheduler(struct task_struct *p, int policy,
         unsigned long flags;
         const struct sched_class *prev_class = p->sched_class;
         struct rq *rq;
+        uid_t euid;
 
         /* may grab non-irq protected spin_locks */
         BUG_ON(in_interrupt());
@@ -5180,8 +5181,9 @@ recheck:
                         return -EPERM;
 
                 /* can't change other user's priorities */
-                if ((current->euid != p->euid) &&
-                    (current->euid != p->uid))
+                euid = current_euid();
+                if (euid != p->euid &&
+                    euid != p->uid)
                         return -EPERM;
         }
 
@@ -5392,6 +5394,7 @@ long sched_setaffinity(pid_t pid, const cpumask_t *in_mask)
         cpumask_t cpus_allowed;
         cpumask_t new_mask = *in_mask;
         struct task_struct *p;
+        uid_t euid;
         int retval;
 
         get_online_cpus();
@@ -5412,9 +5415,9 @@ long sched_setaffinity(pid_t pid, const cpumask_t *in_mask)
         get_task_struct(p);
         read_unlock(&tasklist_lock);
 
+        euid = current_euid();
         retval = -EPERM;
-        if ((current->euid != p->euid) && (current->euid != p->uid) &&
-                        !capable(CAP_SYS_NICE))
+        if (euid != p->euid && euid != p->uid && !capable(CAP_SYS_NICE))
                 goto out_unlock;
 
         retval = security_task_setscheduler(p, 0, NULL);
diff --git a/kernel/signal.c b/kernel/signal.c
index 4530fc654455..167b535fe1a9 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -567,6 +567,7 @@ static int check_kill_permission(int sig, struct siginfo *info,
                                  struct task_struct *t)
 {
         struct pid *sid;
+        uid_t uid, euid;
         int error;
 
         if (!valid_signal(sig))
@@ -579,8 +580,10 @@ static int check_kill_permission(int sig, struct siginfo *info,
         if (error)
                 return error;
 
-        if ((current->euid ^ t->suid) && (current->euid ^ t->uid) &&
-            (current->uid  ^ t->suid) && (current->uid  ^ t->uid) &&
+        uid = current_uid();
+        euid = current_euid();
+        if ((euid ^ t->suid) && (euid ^ t->uid) &&
+            (uid  ^ t->suid) && (uid  ^ t->uid) &&
             !capable(CAP_KILL)) {
                 switch (sig) {
                 case SIGCONT:
@@ -844,7 +847,7 @@ static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
                         q->info.si_errno = 0;
                         q->info.si_code = SI_USER;
                         q->info.si_pid = task_pid_vnr(current);
-                        q->info.si_uid = current->uid;
+                        q->info.si_uid = current_uid();
                         break;
                 case (unsigned long) SEND_SIG_PRIV:
                         q->info.si_signo = sig;
@@ -1598,7 +1601,7 @@ void ptrace_notify(int exit_code)
         info.si_signo = SIGTRAP;
         info.si_code = exit_code;
         info.si_pid = task_pid_vnr(current);
-        info.si_uid = current->uid;
+        info.si_uid = current_uid();
 
         /* Let the debugger run.  */
         spin_lock_irq(&current->sighand->siglock);
@@ -2211,7 +2214,7 @@ sys_kill(pid_t pid, int sig)
         info.si_errno = 0;
         info.si_code = SI_USER;
         info.si_pid = task_tgid_vnr(current);
-        info.si_uid = current->uid;
+        info.si_uid = current_uid();
 
         return kill_something_info(sig, &info, pid);
 }
@@ -2228,7 +2231,7 @@ static int do_tkill(pid_t tgid, pid_t pid, int sig)
         info.si_errno = 0;
         info.si_code = SI_TKILL;
         info.si_pid = task_tgid_vnr(current);
-        info.si_uid = current->uid;
+        info.si_uid = current_uid();
 
         rcu_read_lock();
         p = find_task_by_vpid(pid);
diff --git a/kernel/sys.c b/kernel/sys.c
index 31deba8f7d16..ed5c29c748ac 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -114,10 +114,10 @@ void (*pm_power_off_prepare)(void);
 
 static int set_one_prio(struct task_struct *p, int niceval, int error)
 {
+        uid_t euid = current_euid();
         int no_nice;
 
-        if (p->uid != current->euid &&
-                p->euid != current->euid && !capable(CAP_SYS_NICE)) {
+        if (p->uid != euid && p->euid != euid && !capable(CAP_SYS_NICE)) {
                 error = -EPERM;
                 goto out;
         }
@@ -176,16 +176,16 @@ asmlinkage long sys_setpriority(int which, int who, int niceval)
                 case PRIO_USER:
                         user = current->user;
                         if (!who)
-                                who = current->uid;
+                                who = current_uid();
                         else
-                                if ((who != current->uid) && !(user = find_user(who)))
+                                if (who != current_uid() && !(user = find_user(who)))
                                         goto out_unlock;        /* No processes for this user */
 
                         do_each_thread(g, p)
                                 if (p->uid == who)
                                         error = set_one_prio(p, niceval, error);
                         while_each_thread(g, p);
-                        if (who != current->uid)
+                        if (who != current_uid())
                                 free_uid(user);         /* For find_user() */
                         break;
         }
@@ -238,9 +238,9 @@ asmlinkage long sys_getpriority(int which, int who)
                 case PRIO_USER:
                         user = current->user;
                         if (!who)
-                                who = current->uid;
+                                who = current_uid();
                         else
-                                if ((who != current->uid) && !(user = find_user(who)))
+                                if (who != current_uid() && !(user = find_user(who)))
                                         goto out_unlock;        /* No processes for this user */
 
                         do_each_thread(g, p)
@@ -250,7 +250,7 @@ asmlinkage long sys_getpriority(int which, int who)
                                                 retval = niceval;
                                 }
                         while_each_thread(g, p);
-                        if (who != current->uid)
+                        if (who != current_uid())
                                 free_uid(user);         /* for find_user() */
                         break;
         }
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 9d048fa2d902..511031381c33 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1641,7 +1641,7 @@ out:
 
 static int test_perm(int mode, int op)
 {
-        if (!current->euid)
+        if (!current_euid())
                 mode >>= 6;
         else if (in_egroup_p(0))
                 mode >>= 3;
diff --git a/kernel/timer.c b/kernel/timer.c
index 56becf373c58..b54e4646cee7 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1123,25 +1123,25 @@ asmlinkage long sys_getppid(void)
 asmlinkage long sys_getuid(void)
 {
         /* Only we change this so SMP safe */
-        return current->uid;
+        return current_uid();
 }
 
 asmlinkage long sys_geteuid(void)
 {
         /* Only we change this so SMP safe */
-        return current->euid;
+        return current_euid();
 }
 
 asmlinkage long sys_getgid(void)
 {
         /* Only we change this so SMP safe */
-        return current->gid;
+        return current_gid();
 }
 
 asmlinkage long sys_getegid(void)
 {
         /* Only we change this so SMP safe */
-        return  current->egid;
+        return  current_egid();
 }
 
 #endif
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 532858fa5b88..f82730adea00 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -38,7 +38,7 @@ static struct user_namespace *clone_user_ns(struct user_namespace *old_ns)
         }
 
         /* Reset current->user with a new one */
-        new_user = alloc_uid(ns, current->uid);
+        new_user = alloc_uid(ns, current_uid());
         if (!new_user) {
                 free_uid(ns->root_user);
                 kfree(ns);