FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_acl.c

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (c) 1999-2006, 2016-2017 Robert N. M. Watson
      * All rights reserved.
      *
      * This software was developed by Robert Watson for the TrustedBSD Project.
      *
      * Portions of this software were developed by BAE Systems, the University of
     * Cambridge Computer Laboratory, and Memorial University under DARPA/AFRL
     * contract FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent
     * Computing (TC) research program.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */
    /*
     * Developed by the TrustedBSD Project.
     *
     * ACL system calls and other functions common across different ACL types.
     * Type-specific routines go into subr_acl_<type>.c.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/sysproto.h>
    #include <sys/capsicum.h>
    #include <sys/fcntl.h>
    #include <sys/kernel.h>
    #include <sys/malloc.h>
    #include <sys/mount.h>
    #include <sys/vnode.h>
    #include <sys/lock.h>
    #include <sys/mutex.h>
    #include <sys/namei.h>
    #include <sys/file.h>
    #include <sys/filedesc.h>
    #include <sys/proc.h>
    #include <sys/sysent.h>
    #include <sys/acl.h>
    
    #include <security/audit/audit.h>
    #include <security/mac/mac_framework.h>
    
    CTASSERT(ACL_MAX_ENTRIES >= OLDACL_MAX_ENTRIES);
    
    MALLOC_DEFINE(M_ACL, "acl", "Access Control Lists");
    
    static int      kern___acl_aclcheck_path(struct thread *td, const char *path,
                        acl_type_t type, struct acl *aclp, int follow);
    static int      kern___acl_delete_path(struct thread *td, const char *path,
                        acl_type_t type, int follow);
    static int      kern___acl_get_path(struct thread *td, const char *path,
                        acl_type_t type, struct acl *aclp, int follow);
    static int      kern___acl_set_path(struct thread *td, const char *path,
                        acl_type_t type, const struct acl *aclp, int follow);
    static int      vacl_set_acl(struct thread *td, struct vnode *vp,
                        acl_type_t type, const struct acl *aclp);
    static int      vacl_get_acl(struct thread *td, struct vnode *vp,
                        acl_type_t type, struct acl *aclp);
    static int      vacl_aclcheck(struct thread *td, struct vnode *vp,
                        acl_type_t type, const struct acl *aclp);
    
    int
    acl_copy_oldacl_into_acl(const struct oldacl *source, struct acl *dest)
    {
            int i;
    
            if (source->acl_cnt < 0 || source->acl_cnt > OLDACL_MAX_ENTRIES)
                    return (EINVAL);
    
            bzero(dest, sizeof(*dest));
    
            dest->acl_cnt = source->acl_cnt;
            dest->acl_maxcnt = ACL_MAX_ENTRIES;
    
            for (i = 0; i < dest->acl_cnt; i++) {
                    dest->acl_entry[i].ae_tag = source->acl_entry[i].ae_tag;
                   dest->acl_entry[i].ae_id = source->acl_entry[i].ae_id;
                   dest->acl_entry[i].ae_perm = source->acl_entry[i].ae_perm;
           }
   
           return (0);
   }
   
   int
   acl_copy_acl_into_oldacl(const struct acl *source, struct oldacl *dest)
   {
           int i;
   
           if (source->acl_cnt > OLDACL_MAX_ENTRIES)
                   return (EINVAL);
   
           bzero(dest, sizeof(*dest));
   
           dest->acl_cnt = source->acl_cnt;
   
           for (i = 0; i < dest->acl_cnt; i++) {
                   dest->acl_entry[i].ae_tag = source->acl_entry[i].ae_tag;
                   dest->acl_entry[i].ae_id = source->acl_entry[i].ae_id;
                   dest->acl_entry[i].ae_perm = source->acl_entry[i].ae_perm;
           }
   
           return (0);
   }
   
   /*
    * At one time, "struct ACL" was extended in order to add support for NFSv4
    * ACLs.  Instead of creating compatibility versions of all the ACL-related
    * syscalls, they were left intact.  It's possible to find out what the code
    * calling these syscalls (libc) expects basing on "type" argument - if it's
    * either ACL_TYPE_ACCESS_OLD or ACL_TYPE_DEFAULT_OLD (which previously were
    * known as ACL_TYPE_ACCESS and ACL_TYPE_DEFAULT), then it's the "struct
    * oldacl".  If it's something else, then it's the new "struct acl".  In the
    * latter case, the routines below just copyin/copyout the contents.  In the
    * former case, they copyin the "struct oldacl" and convert it to the new
    * format.
    */
   static int
   acl_copyin(const void *user_acl, struct acl *kernel_acl, acl_type_t type)
   {
           int error;
           struct oldacl old;
   
           switch (type) {
           case ACL_TYPE_ACCESS_OLD:
           case ACL_TYPE_DEFAULT_OLD:
                   error = copyin(user_acl, &old, sizeof(old));
                   if (error != 0)
                           break;
                   acl_copy_oldacl_into_acl(&old, kernel_acl);
                   break;
   
           default:
                   error = copyin(user_acl, kernel_acl, sizeof(*kernel_acl));
                   if (kernel_acl->acl_maxcnt != ACL_MAX_ENTRIES)
                           return (EINVAL);
           }
   
           return (error);
   }
   
   static int
   acl_copyout(const struct acl *kernel_acl, void *user_acl, acl_type_t type)
   {
           uint32_t am;
           int error;
           struct oldacl old;
   
           switch (type) {
           case ACL_TYPE_ACCESS_OLD:
           case ACL_TYPE_DEFAULT_OLD:
                   error = acl_copy_acl_into_oldacl(kernel_acl, &old);
                   if (error != 0)
                           break;
   
                   error = copyout(&old, user_acl, sizeof(old));
                   break;
   
           default:
                   error = fueword32((char *)user_acl +
                       offsetof(struct acl, acl_maxcnt), &am);
                   if (error == -1)
                           return (EFAULT);
                   if (am != ACL_MAX_ENTRIES)
                           return (EINVAL);
   
                   error = copyout(kernel_acl, user_acl, sizeof(*kernel_acl));
           }
   
           return (error);
   }
   
   /*
    * Convert "old" type - ACL_TYPE_{ACCESS,DEFAULT}_OLD - into its "new"
    * counterpart.  It's required for old (pre-NFSv4 ACLs) libc to work
    * with new kernel.  Fixing 'type' for old binaries with new libc
    * is being done in lib/libc/posix1e/acl_support.c:_acl_type_unold().
    */
   static int
   acl_type_unold(int type)
   {
           switch (type) {
           case ACL_TYPE_ACCESS_OLD:
                   return (ACL_TYPE_ACCESS);
   
           case ACL_TYPE_DEFAULT_OLD:
                   return (ACL_TYPE_DEFAULT);
   
           default:
                   return (type);
           }
   }
   
   /*
    * These calls wrap the real vnode operations, and are called by the syscall
    * code once the syscall has converted the path or file descriptor to a vnode
    * (unlocked).  The aclp pointer is assumed still to point to userland, so
    * this should not be consumed within the kernel except by syscall code.
    * Other code should directly invoke VOP_{SET,GET}ACL.
    */
   
   /*
    * Given a vnode, set its ACL.
    */
   static int
   vacl_set_acl(struct thread *td, struct vnode *vp, acl_type_t type,
       const struct acl *aclp)
   {
           struct acl *inkernelacl;
           struct mount *mp;
           int error;
   
           AUDIT_ARG_VALUE(type);
           inkernelacl = acl_alloc(M_WAITOK);
           error = acl_copyin(aclp, inkernelacl, type);
           if (error != 0)
                   goto out;
           error = vn_start_write(vp, &mp, V_WAIT | PCATCH);
           if (error != 0)
                   goto out;
           vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
           AUDIT_ARG_VNODE1(vp);
   #ifdef MAC
           error = mac_vnode_check_setacl(td->td_ucred, vp, type, inkernelacl);
           if (error != 0)
                   goto out_unlock;
   #endif
           error = VOP_SETACL(vp, acl_type_unold(type), inkernelacl,
               td->td_ucred, td);
   #ifdef MAC
   out_unlock:
   #endif
           VOP_UNLOCK(vp);
           vn_finished_write(mp);
   out:
           acl_free(inkernelacl);
           return (error);
   }
   
   /*
    * Given a vnode, get its ACL.
    */
   static int
   vacl_get_acl(struct thread *td, struct vnode *vp, acl_type_t type,
       struct acl *aclp)
   {
           struct acl *inkernelacl;
           int error;
   
           AUDIT_ARG_VALUE(type);
           inkernelacl = acl_alloc(M_WAITOK | M_ZERO);
           vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
           AUDIT_ARG_VNODE1(vp);
   #ifdef MAC
           error = mac_vnode_check_getacl(td->td_ucred, vp, type);
           if (error != 0)
                   goto out;
   #endif
           error = VOP_GETACL(vp, acl_type_unold(type), inkernelacl,
               td->td_ucred, td);
   
   #ifdef MAC
   out:
   #endif
           VOP_UNLOCK(vp);
           if (error == 0)
                   error = acl_copyout(inkernelacl, aclp, type);
           acl_free(inkernelacl);
           return (error);
   }
   
   /*
    * Given a vnode, delete its ACL.
    */
   static int
   vacl_delete(struct thread *td, struct vnode *vp, acl_type_t type)
   {
           struct mount *mp;
           int error;
   
           AUDIT_ARG_VALUE(type);
           error = vn_start_write(vp, &mp, V_WAIT | PCATCH);
           if (error != 0)
                   return (error);
           vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
           AUDIT_ARG_VNODE1(vp);
   #ifdef MAC
           error = mac_vnode_check_deleteacl(td->td_ucred, vp, type);
           if (error != 0)
                   goto out;
   #endif
           error = VOP_SETACL(vp, acl_type_unold(type), 0, td->td_ucred, td);
   #ifdef MAC
   out:
   #endif
           VOP_UNLOCK(vp);
           vn_finished_write(mp);
           return (error);
   }
   
   /*
    * Given a vnode, check whether an ACL is appropriate for it
    *
    * XXXRW: No vnode lock held so can't audit vnode state...?
    */
   static int
   vacl_aclcheck(struct thread *td, struct vnode *vp, acl_type_t type,
       const struct acl *aclp)
   {
           struct acl *inkernelacl;
           int error;
   
           inkernelacl = acl_alloc(M_WAITOK);
           error = acl_copyin(aclp, inkernelacl, type);
           if (error != 0)
                   goto out;
           error = VOP_ACLCHECK(vp, acl_type_unold(type), inkernelacl,
               td->td_ucred, td);
   out:
           acl_free(inkernelacl);
           return (error);
   }
   
   /*
    * syscalls -- convert the path/fd to a vnode, and call vacl_whatever.  Don't
    * need to lock, as the vacl_ code will get/release any locks required.
    */
   
   /*
    * Given a file path, get an ACL for it
    */
   int
   sys___acl_get_file(struct thread *td, struct __acl_get_file_args *uap)
   {
   
           return (kern___acl_get_path(td, uap->path, uap->type, uap->aclp,
               FOLLOW));
   }
   
   /*
    * Given a file path, get an ACL for it; don't follow links.
    */
   int
   sys___acl_get_link(struct thread *td, struct __acl_get_link_args *uap)
   {
   
           return(kern___acl_get_path(td, uap->path, uap->type, uap->aclp,
               NOFOLLOW));
   }
   
   static int
   kern___acl_get_path(struct thread *td, const char *path, acl_type_t type,
       struct acl *aclp, int follow)
   {
           struct nameidata nd;
           int error;
   
           NDINIT(&nd, LOOKUP, follow | AUDITVNODE1, UIO_USERSPACE, path, td);
           error = namei(&nd);
           if (error == 0) {
                   error = vacl_get_acl(td, nd.ni_vp, type, aclp);
                   NDFREE(&nd, 0);
           }
           return (error);
   }
   
   /*
    * Given a file path, set an ACL for it.
    */
   int
   sys___acl_set_file(struct thread *td, struct __acl_set_file_args *uap)
   {
   
           return(kern___acl_set_path(td, uap->path, uap->type, uap->aclp,
               FOLLOW));
   }
   
   /*
    * Given a file path, set an ACL for it; don't follow links.
    */
   int
   sys___acl_set_link(struct thread *td, struct __acl_set_link_args *uap)
   {
   
           return(kern___acl_set_path(td, uap->path, uap->type, uap->aclp,
               NOFOLLOW));
   }
   
   static int
   kern___acl_set_path(struct thread *td, const char *path,
       acl_type_t type, const struct acl *aclp, int follow)
   {
           struct nameidata nd;
           int error;
   
           NDINIT(&nd, LOOKUP, follow | AUDITVNODE1, UIO_USERSPACE, path, td);
           error = namei(&nd);
           if (error == 0) {
                   error = vacl_set_acl(td, nd.ni_vp, type, aclp);
                   NDFREE(&nd, 0);
           }
           return (error);
   }
   
   /*
    * Given a file descriptor, get an ACL for it.
    */
   int
   sys___acl_get_fd(struct thread *td, struct __acl_get_fd_args *uap)
   {
           struct file *fp;
           cap_rights_t rights;
           int error;
   
           AUDIT_ARG_FD(uap->filedes);
           error = getvnode(td, uap->filedes,
               cap_rights_init_one(&rights, CAP_ACL_GET), &fp);
           if (error == 0) {
                   error = vacl_get_acl(td, fp->f_vnode, uap->type, uap->aclp);
                   fdrop(fp, td);
           }
           return (error);
   }
   
   /*
    * Given a file descriptor, set an ACL for it.
    */
   int
   sys___acl_set_fd(struct thread *td, struct __acl_set_fd_args *uap)
   {
           struct file *fp;
           cap_rights_t rights;
           int error;
   
           AUDIT_ARG_FD(uap->filedes);
           error = getvnode(td, uap->filedes,
               cap_rights_init_one(&rights, CAP_ACL_SET), &fp);
           if (error == 0) {
                   error = vacl_set_acl(td, fp->f_vnode, uap->type, uap->aclp);
                   fdrop(fp, td);
           }
           return (error);
   }
   
   /*
    * Given a file path, delete an ACL from it.
    */
   int
   sys___acl_delete_file(struct thread *td, struct __acl_delete_file_args *uap)
   {
   
           return (kern___acl_delete_path(td, uap->path, uap->type, FOLLOW));
   }
   
   /*
    * Given a file path, delete an ACL from it; don't follow links.
    */
   int
   sys___acl_delete_link(struct thread *td, struct __acl_delete_link_args *uap)
   {
   
           return (kern___acl_delete_path(td, uap->path, uap->type, NOFOLLOW));
   }
   
   static int
   kern___acl_delete_path(struct thread *td, const char *path,
       acl_type_t type, int follow)
   {
           struct nameidata nd;
           int error;
   
           NDINIT(&nd, LOOKUP, follow, UIO_USERSPACE, path, td);
           error = namei(&nd);
           if (error == 0) {
                   error = vacl_delete(td, nd.ni_vp, type);
                   NDFREE(&nd, 0);
           }
           return (error);
   }
   
   /*
    * Given a file path, delete an ACL from it.
    */
   int
   sys___acl_delete_fd(struct thread *td, struct __acl_delete_fd_args *uap)
   {
           struct file *fp;
           cap_rights_t rights;
           int error;
   
           AUDIT_ARG_FD(uap->filedes);
           error = getvnode(td, uap->filedes,
               cap_rights_init_one(&rights, CAP_ACL_DELETE), &fp);
           if (error == 0) {
                   error = vacl_delete(td, fp->f_vnode, uap->type);
                   fdrop(fp, td);
           }
           return (error);
   }
   
   /*
    * Given a file path, check an ACL for it.
    */
   int
   sys___acl_aclcheck_file(struct thread *td, struct __acl_aclcheck_file_args *uap)
   {
   
           return (kern___acl_aclcheck_path(td, uap->path, uap->type, uap->aclp,
               FOLLOW));
   }
   
   /*
    * Given a file path, check an ACL for it; don't follow links.
    */
   int
   sys___acl_aclcheck_link(struct thread *td, struct __acl_aclcheck_link_args *uap)
   {
           return (kern___acl_aclcheck_path(td, uap->path, uap->type, uap->aclp,
               NOFOLLOW));
   }
   
   static int
   kern___acl_aclcheck_path(struct thread *td, const char *path, acl_type_t type,
       struct acl *aclp, int follow)
   {
           struct nameidata nd;
           int error;
   
           NDINIT(&nd, LOOKUP, follow, UIO_USERSPACE, path, td);
           error = namei(&nd);
           if (error == 0) {
                   error = vacl_aclcheck(td, nd.ni_vp, type, aclp);
                   NDFREE(&nd, 0);
           }
           return (error);
   }
   
   /*
    * Given a file descriptor, check an ACL for it.
    */
   int
   sys___acl_aclcheck_fd(struct thread *td, struct __acl_aclcheck_fd_args *uap)
   {
           struct file *fp;
           cap_rights_t rights;
           int error;
   
           AUDIT_ARG_FD(uap->filedes);
           error = getvnode(td, uap->filedes,
               cap_rights_init_one(&rights, CAP_ACL_CHECK), &fp);
           if (error == 0) {
                   error = vacl_aclcheck(td, fp->f_vnode, uap->type, uap->aclp);
                   fdrop(fp, td);
           }
           return (error);
   }
   
   struct acl *
   acl_alloc(int flags)
   {
           struct acl *aclp;
   
           aclp = malloc(sizeof(*aclp), M_ACL, flags);
           if (aclp == NULL)
                   return (NULL);
   
           aclp->acl_maxcnt = ACL_MAX_ENTRIES;
   
           return (aclp);
   }
   
   void
   acl_free(struct acl *aclp)
   {
   
           free(aclp, M_ACL);
   }

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