userns: Kill nsown_capable it makes the wrong thing easy

nsown_capable is a special case of ns_capable essentially for just CAP_SETUID and
CAP_SETGID.  For the existing users it doesn't noticably simplify things and
from the suggested patches I have seen it encourages people to do the wrong
thing.  So remove nsown_capable.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

6 files changed, 14 insertions, 26 deletions

diff --git a/kernel/capability.c b/kernel/capability.c
index f6c2ce5701e1..6fc1c8af44df 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -433,18 +433,6 @@ bool capable(int cap)
 EXPORT_SYMBOL(capable);
 
 /**
- * nsown_capable - Check superior capability to one's own user_ns
- * @cap: The capability in question
- *
- * Return true if the current task has the given superior capability
- * targeted at its own user namespace.
- */
-bool nsown_capable(int cap)
-{
-        return ns_capable(current_user_ns(), cap);
-}
-
-/**
  * inode_capable - Check superior capability over inode
  * @inode: The inode in question
  * @cap: The capability in question
diff --git a/kernel/groups.c b/kernel/groups.c
index 6b2588dd04ff..90cf1c38c8ea 100644
--- a/kernel/groups.c
+++ b/kernel/groups.c
@@ -233,7 +233,7 @@ SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist)
         struct group_info *group_info;
         int retval;
 
-        if (!nsown_capable(CAP_SETGID))
+        if (!ns_capable(current_user_ns(), CAP_SETGID))
                 return -EPERM;
         if ((unsigned)gidsetsize > NGROUPS_MAX)
                 return -EINVAL;
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 6917e8edb48e..ee1f6bb83d67 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -329,7 +329,7 @@ static int pidns_install(struct nsproxy *nsproxy, void *ns)
         struct pid_namespace *ancestor, *new = ns;
 
         if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) ||
-            !nsown_capable(CAP_SYS_ADMIN))
+            !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
                 return -EPERM;
 
         /*
diff --git a/kernel/sys.c b/kernel/sys.c
index 771129b299f8..c18ecca575b4 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -337,7 +337,7 @@ SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid)
         if (rgid != (gid_t) -1) {
                 if (gid_eq(old->gid, krgid) ||
                     gid_eq(old->egid, krgid) ||
-                    nsown_capable(CAP_SETGID))
+                    ns_capable(old->user_ns, CAP_SETGID))
                         new->gid = krgid;
                 else
                         goto error;
@@ -346,7 +346,7 @@ SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid)
                 if (gid_eq(old->gid, kegid) ||
                     gid_eq(old->egid, kegid) ||
                     gid_eq(old->sgid, kegid) ||
-                    nsown_capable(CAP_SETGID))
+                    ns_capable(old->user_ns, CAP_SETGID))
                         new->egid = kegid;
                 else
                         goto error;
@@ -387,7 +387,7 @@ SYSCALL_DEFINE1(setgid, gid_t, gid)
         old = current_cred();
 
         retval = -EPERM;
-        if (nsown_capable(CAP_SETGID))
+        if (ns_capable(old->user_ns, CAP_SETGID))
                 new->gid = new->egid = new->sgid = new->fsgid = kgid;
         else if (gid_eq(kgid, old->gid) || gid_eq(kgid, old->sgid))
                 new->egid = new->fsgid = kgid;
@@ -471,7 +471,7 @@ SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid)
                 new->uid = kruid;
                 if (!uid_eq(old->uid, kruid) &&
                     !uid_eq(old->euid, kruid) &&
-                    !nsown_capable(CAP_SETUID))
+                    !ns_capable(old->user_ns, CAP_SETUID))
                         goto error;
         }
 
@@ -480,7 +480,7 @@ SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid)
                 if (!uid_eq(old->uid, keuid) &&
                     !uid_eq(old->euid, keuid) &&
                     !uid_eq(old->suid, keuid) &&
-                    !nsown_capable(CAP_SETUID))
+                    !ns_capable(old->user_ns, CAP_SETUID))
                         goto error;
         }
 
@@ -534,7 +534,7 @@ SYSCALL_DEFINE1(setuid, uid_t, uid)
         old = current_cred();
 
         retval = -EPERM;
-        if (nsown_capable(CAP_SETUID)) {
+        if (ns_capable(old->user_ns, CAP_SETUID)) {
                 new->suid = new->uid = kuid;
                 if (!uid_eq(kuid, old->uid)) {
                         retval = set_user(new);
@@ -591,7 +591,7 @@ SYSCALL_DEFINE3(setresuid, uid_t, ruid, uid_t, euid, uid_t, suid)
         old = current_cred();
 
         retval = -EPERM;
-        if (!nsown_capable(CAP_SETUID)) {
+        if (!ns_capable(old->user_ns, CAP_SETUID)) {
                 if (ruid != (uid_t) -1        && !uid_eq(kruid, old->uid) &&
                     !uid_eq(kruid, old->euid) && !uid_eq(kruid, old->suid))
                         goto error;
@@ -673,7 +673,7 @@ SYSCALL_DEFINE3(setresgid, gid_t, rgid, gid_t, egid, gid_t, sgid)
         old = current_cred();
 
         retval = -EPERM;
-        if (!nsown_capable(CAP_SETGID)) {
+        if (!ns_capable(old->user_ns, CAP_SETGID)) {
                 if (rgid != (gid_t) -1        && !gid_eq(krgid, old->gid) &&
                     !gid_eq(krgid, old->egid) && !gid_eq(krgid, old->sgid))
                         goto error;
@@ -744,7 +744,7 @@ SYSCALL_DEFINE1(setfsuid, uid_t, uid)
 
         if (uid_eq(kuid, old->uid)  || uid_eq(kuid, old->euid)  ||
             uid_eq(kuid, old->suid) || uid_eq(kuid, old->fsuid) ||
-            nsown_capable(CAP_SETUID)) {
+            ns_capable(old->user_ns, CAP_SETUID)) {
                 if (!uid_eq(kuid, old->fsuid)) {
                         new->fsuid = kuid;
                         if (security_task_fix_setuid(new, old, LSM_SETID_FS) == 0)
@@ -783,7 +783,7 @@ SYSCALL_DEFINE1(setfsgid, gid_t, gid)
 
         if (gid_eq(kgid, old->gid)  || gid_eq(kgid, old->egid)  ||
             gid_eq(kgid, old->sgid) || gid_eq(kgid, old->fsgid) ||
-            nsown_capable(CAP_SETGID)) {
+            ns_capable(old->user_ns, CAP_SETGID)) {
                 if (!gid_eq(kgid, old->fsgid)) {
                         new->fsgid = kgid;
                         goto change_okay;
diff --git a/kernel/uid16.c b/kernel/uid16.c
index f6c83d7ef000..602e5bbbceff 100644
--- a/kernel/uid16.c
+++ b/kernel/uid16.c
@@ -176,7 +176,7 @@ SYSCALL_DEFINE2(setgroups16, int, gidsetsize, old_gid_t __user *, grouplist)
         struct group_info *group_info;
         int retval;
 
-        if (!nsown_capable(CAP_SETGID))
+        if (!ns_capable(current_user_ns(), CAP_SETGID))
                 return -EPERM;
         if ((unsigned)gidsetsize > NGROUPS_MAX)
                 return -EINVAL;
diff --git a/kernel/utsname.c b/kernel/utsname.c
index 2fc8576efaa8..fd393124e507 100644
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -114,7 +114,7 @@ static int utsns_install(struct nsproxy *nsproxy, void *new)
         struct uts_namespace *ns = new;
 
         if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
-            !nsown_capable(CAP_SYS_ADMIN))
+            !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
                 return -EPERM;
 
         get_uts_ns(ns);