[REVIEW][PATCH 5/5] userns: Kill nsown_capable it makes the wrong thing easy

[ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman)]

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.

Signed-off-by: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
---
 fs/namespace.c             |    4 ++--
 fs/open.c                  |    2 +-
 include/linux/capability.h |    1 -
 ipc/namespace.c            |    2 +-
 kernel/capability.c        |   12 ------------
 kernel/groups.c            |    2 +-
 kernel/pid_namespace.c     |    2 +-
 kernel/sys.c               |   20 ++++++++++----------
 kernel/uid16.c             |    2 +-
 kernel/utsname.c           |    2 +-
 net/core/net_namespace.c   |    2 +-
 net/core/scm.c             |    4 ++--
 12 files changed, 21 insertions(+), 34 deletions(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index 877e427..dc519a1 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2929,8 +2929,8 @@ static int mntns_install(struct nsproxy *nsproxy, void *ns)
 	struct path root;
 
 	if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) ||
-	    !nsown_capable(CAP_SYS_CHROOT) ||
-	    !nsown_capable(CAP_SYS_ADMIN))
+	    !ns_capable(current_user_ns(), CAP_SYS_CHROOT) ||
+	    !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
 		return -EPERM;
 
 	if (fs->users != 1)
diff --git a/fs/open.c b/fs/open.c
index 9156cb0..2a57580 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -443,7 +443,7 @@ retry:
 		goto dput_and_out;
 
 	error = -EPERM;
-	if (!nsown_capable(CAP_SYS_CHROOT))
+	if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
 		goto dput_and_out;
 	error = security_path_chroot(&path);
 	if (error)
diff --git a/include/linux/capability.h b/include/linux/capability.h
index d9a4f7f..a6ee1f9 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -210,7 +210,6 @@ extern bool has_ns_capability_noaudit(struct task_struct *t,
 				      struct user_namespace *ns, int cap);
 extern bool capable(int cap);
 extern bool ns_capable(struct user_namespace *ns, int cap);
-extern bool nsown_capable(int cap);
 extern bool inode_capable(const struct inode *inode, int cap);
 extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap);
 
diff --git a/ipc/namespace.c b/ipc/namespace.c
index 7ee61bf..4be6581 100644
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -171,7 +171,7 @@ static int ipcns_install(struct nsproxy *nsproxy, void *new)
 {
 	struct ipc_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;
 
 	/* Ditch state from the old ipc namespace */
diff --git a/kernel/capability.c b/kernel/capability.c
index f6c2ce5..6fc1c8a 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 6b2588d..90cf1c3 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 6917e8e..ee1f6bb 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 771129b..c18ecca 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 f6c83d7..602e5bb 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 2fc8576..fd39312 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);
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index f9765203..81d3a9a 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -651,7 +651,7 @@ static int netns_install(struct nsproxy *nsproxy, void *ns)
 	struct net *net = ns;
 
 	if (!ns_capable(net->user_ns, CAP_SYS_ADMIN) ||
-	    !nsown_capable(CAP_SYS_ADMIN))
+	    !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
 		return -EPERM;
 
 	put_net(nsproxy->net_ns);
diff --git a/net/core/scm.c b/net/core/scm.c
index 03795d0..c346f58 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -56,9 +56,9 @@ static __inline__ int scm_check_creds(struct ucred *creds)
 	if ((creds->pid == task_tgid_vnr(current) ||
 	     ns_capable(current->nsproxy->pid_ns->user_ns, CAP_SYS_ADMIN)) &&
 	    ((uid_eq(uid, cred->uid)   || uid_eq(uid, cred->euid) ||
-	      uid_eq(uid, cred->suid)) || nsown_capable(CAP_SETUID)) &&
+	      uid_eq(uid, cred->suid)) || ns_capable(cred->user_ns, CAP_SETUID)) &&
 	    ((gid_eq(gid, cred->gid)   || gid_eq(gid, cred->egid) ||
-	      gid_eq(gid, cred->sgid)) || nsown_capable(CAP_SETGID))) {
+	      gid_eq(gid, cred->sgid)) || ns_capable(cred->user_ns, CAP_SETGID))) {
 	       return 0;
 	}
 	return -EPERM;
-- 
1.7.5.4