Implement new world order in VFS locking for ACLs. This will remove the

unconditional acquisition of Giant for ACL related operations. If the file
system is set as being MP safe and debug.mpsafevfs is 1, do not pickup
giant.

For any operations which require namei(9) lookups:

__acl_get_file
__acl_get_link
__acl_set_file
__acl_set_link
__acl_delete_file
__acl_delete_link
__acl_aclcheck_file
__acl_aclcheck_link

-Set the MPSAFE flag in NDINIT
-Initialize vfslocked variable using the NDHASGIANT macro

For functions which operate on fds, make sure the operations are locked:

__acl_get_fd
__acl_set_fd
__acl_delete_fd
__acl_aclcheck_fd

-Initialize vfslocked using VFS_LOCK_GIANT before we manipulate the vnode

Discussed with:	jeff

1 files changed, 45 insertions, 44 deletions

diff --git a/sys/kern/subr_acl_posix1e.c b/sys/kern/subr_acl_posix1e.c
index f238b98..f346f61 100644
--- a/sys/kern/subr_acl_posix1e.c
+++ b/sys/kern/subr_acl_posix1e.c
@@ -41,6 +41,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/kernel.h>
 #include <sys/mac.h>
 #include <sys/malloc.h>
+#include <sys/mount.h>
 #include <sys/vnode.h>
 #include <sys/lock.h>
 #include <sys/mutex.h>
@@ -772,16 +773,16 @@ int
 __acl_get_file(struct thread *td, struct __acl_get_file_args *uap)
 {
 	struct nameidata nd;
-	int error;
+	int vfslocked, error;
 
-	mtx_lock(&Giant);
-	NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->path, td);
+	NDINIT(&nd, LOOKUP, MPSAFE|FOLLOW, UIO_USERSPACE, uap->path, td);
 	error = namei(&nd);
+	vfslocked = NDHASGIANT(&nd);
 	if (error == 0) {
 		error = vacl_get_acl(td, nd.ni_vp, uap->type, uap->aclp);
 		NDFREE(&nd, 0);
 	}
-	mtx_unlock(&Giant);
+	VFS_UNLOCK_GIANT(vfslocked);
 	return (error);
 }
 
@@ -794,16 +795,16 @@ int
 __acl_get_link(struct thread *td, struct __acl_get_link_args *uap)
 {
 	struct nameidata nd;
-	int error;
+	int vfslocked, error;
 
-	mtx_lock(&Giant);
-	NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, uap->path, td);
+	NDINIT(&nd, LOOKUP, MPSAFE|NOFOLLOW, UIO_USERSPACE, uap->path, td);
 	error = namei(&nd);
+	vfslocked = NDHASGIANT(&nd);
 	if (error == 0) {
 		error = vacl_get_acl(td, nd.ni_vp, uap->type, uap->aclp);
 		NDFREE(&nd, 0);
 	}
-	mtx_unlock(&Giant);
+	VFS_UNLOCK_GIANT(vfslocked);
 	return (error);
 }
 
@@ -816,16 +817,16 @@ int
 __acl_set_file(struct thread *td, struct __acl_set_file_args *uap)
 {
 	struct nameidata nd;
-	int error;
+	int vfslocked, error;
 
-	mtx_lock(&Giant);
-	NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->path, td);
+	NDINIT(&nd, LOOKUP, MPSAFE|FOLLOW, UIO_USERSPACE, uap->path, td);
 	error = namei(&nd);
+	vfslocked = NDHASGIANT(&nd);
 	if (error == 0) {
 		error = vacl_set_acl(td, nd.ni_vp, uap->type, uap->aclp);
 		NDFREE(&nd, 0);
 	}
-	mtx_unlock(&Giant);
+	VFS_UNLOCK_GIANT(vfslocked);
 	return (error);
 }
 
@@ -838,16 +839,16 @@ int
 __acl_set_link(struct thread *td, struct __acl_set_link_args *uap)
 {
 	struct nameidata nd;
-	int error;
+	int vfslocked, error;
 
-	mtx_lock(&Giant);
-	NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, uap->path, td);
+	NDINIT(&nd, LOOKUP, MPSAFE|NOFOLLOW, UIO_USERSPACE, uap->path, td);
 	error = namei(&nd);
+	vfslocked = NDHASGIANT(&nd);
 	if (error == 0) {
 		error = vacl_set_acl(td, nd.ni_vp, uap->type, uap->aclp);
 		NDFREE(&nd, 0);
 	}
-	mtx_unlock(&Giant);
+	VFS_UNLOCK_GIANT(vfslocked);
 	return (error);
 }
 
@@ -860,15 +861,15 @@ int
 __acl_get_fd(struct thread *td, struct __acl_get_fd_args *uap)
 {
 	struct file *fp;
-	int error;
+	int vfslocked, error;
 
-	mtx_lock(&Giant);
 	error = getvnode(td->td_proc->p_fd, uap->filedes, &fp);
 	if (error == 0) {
+		vfslocked = VFS_LOCK_GIANT(fp->f_vnode->v_mount);
 		error = vacl_get_acl(td, fp->f_vnode, uap->type, uap->aclp);
 		fdrop(fp, td);
+		VFS_UNLOCK_GIANT(vfslocked);
 	}
-	mtx_unlock(&Giant);
 	return (error);
 }
 
@@ -881,15 +882,15 @@ int
 __acl_set_fd(struct thread *td, struct __acl_set_fd_args *uap)
 {
 	struct file *fp;
-	int error;
+	int vfslocked, error;
 
-	mtx_lock(&Giant);
 	error = getvnode(td->td_proc->p_fd, uap->filedes, &fp);
 	if (error == 0) {
+		vfslocked = VFS_LOCK_GIANT(fp->f_vnode->v_mount);
 		error = vacl_set_acl(td, fp->f_vnode, uap->type, uap->aclp);
 		fdrop(fp, td);
+		VFS_UNLOCK_GIANT(vfslocked);
 	}
-	mtx_unlock(&Giant);
 	return (error);
 }
 
@@ -902,16 +903,16 @@ int
 __acl_delete_file(struct thread *td, struct __acl_delete_file_args *uap)
 {
 	struct nameidata nd;
-	int error;
+	int vfslocked, error;
 
-	mtx_lock(&Giant);
-	NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->path, td);
+	NDINIT(&nd, LOOKUP, MPSAFE|FOLLOW, UIO_USERSPACE, uap->path, td);
 	error = namei(&nd);
+	vfslocked = NDHASGIANT(&nd);
 	if (error == 0) {
 		error = vacl_delete(td, nd.ni_vp, uap->type);
 		NDFREE(&nd, 0);
 	}
-	mtx_unlock(&Giant);
+	VFS_UNLOCK_GIANT(vfslocked);
 	return (error);
 }
 
@@ -924,16 +925,16 @@ int
 __acl_delete_link(struct thread *td, struct __acl_delete_link_args *uap)
 {
 	struct nameidata nd;
-	int error;
+	int vfslocked, error;
 
-	mtx_lock(&Giant);
-	NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, uap->path, td);
+	NDINIT(&nd, LOOKUP, MPSAFE|NOFOLLOW, UIO_USERSPACE, uap->path, td);
 	error = namei(&nd);
+	vfslocked = NDHASGIANT(&nd);
 	if (error == 0) {
 		error = vacl_delete(td, nd.ni_vp, uap->type);
 		NDFREE(&nd, 0);
 	}
-	mtx_unlock(&Giant);
+	VFS_UNLOCK_GIANT(vfslocked);
 	return (error);
 }
 
@@ -946,15 +947,15 @@ int
 __acl_delete_fd(struct thread *td, struct __acl_delete_fd_args *uap)
 {
 	struct file *fp;
-	int error;
+	int vfslocked, error;
 
-	mtx_lock(&Giant);
 	error = getvnode(td->td_proc->p_fd, uap->filedes, &fp);
 	if (error == 0) {
+		vfslocked = VFS_LOCK_GIANT(fp->f_vnode->v_mount);
 		error = vacl_delete(td, fp->f_vnode, uap->type);
 		fdrop(fp, td);
+		VFS_UNLOCK_GIANT(vfslocked);
 	}
-	mtx_unlock(&Giant);
 	return (error);
 }
 
@@ -967,16 +968,16 @@ int
 __acl_aclcheck_file(struct thread *td, struct __acl_aclcheck_file_args *uap)
 {
 	struct nameidata	nd;
-	int	error;
+	int vfslocked, error;
 
-	mtx_lock(&Giant);
-	NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->path, td);
+	NDINIT(&nd, LOOKUP, MPSAFE|FOLLOW, UIO_USERSPACE, uap->path, td);
 	error = namei(&nd);
+	vfslocked = NDHASGIANT(&nd);
 	if (error == 0) {
 		error = vacl_aclcheck(td, nd.ni_vp, uap->type, uap->aclp);
 		NDFREE(&nd, 0);
 	}
-	mtx_unlock(&Giant);
+	VFS_UNLOCK_GIANT(vfslocked);
 	return (error);
 }
 
@@ -989,16 +990,16 @@ int
 __acl_aclcheck_link(struct thread *td, struct __acl_aclcheck_link_args *uap)
 {
 	struct nameidata	nd;
-	int	error;
+	int vfslocked, error;
 
-	mtx_lock(&Giant);
-	NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_USERSPACE, uap->path, td);
+	NDINIT(&nd, LOOKUP, MPSAFE|NOFOLLOW, UIO_USERSPACE, uap->path, td);
 	error = namei(&nd);
+	vfslocked = NDHASGIANT(&nd);
 	if (error == 0) {
 		error = vacl_aclcheck(td, nd.ni_vp, uap->type, uap->aclp);
 		NDFREE(&nd, 0);
 	}
-	mtx_unlock(&Giant);
+	VFS_UNLOCK_GIANT(vfslocked);
 	return (error);
 }
 
@@ -1011,15 +1012,15 @@ int
 __acl_aclcheck_fd(struct thread *td, struct __acl_aclcheck_fd_args *uap)
 {
 	struct file *fp;
-	int error;
+	int vfslocked, error;
 
-	mtx_lock(&Giant);
 	error = getvnode(td->td_proc->p_fd, uap->filedes, &fp);
 	if (error == 0) {
+		vfslocked = VFS_LOCK_GIANT(fp->f_vnode->v_mount);
 		error = vacl_aclcheck(td, fp->f_vnode, uap->type, uap->aclp);
 		fdrop(fp, td);
+		VFS_UNLOCK_GIANT(vfslocked);
 	}
-	mtx_unlock(&Giant);
 	return (error);
 }