/*- * Copyright (c) 1999, 2000, 2001 Robert N. M. Watson * All rights reserved. * * 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. * * $FreeBSD$ */ /* * Developed by the TrustedBSD Project. * Support for POSIX.1e access control lists. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include MALLOC_DEFINE(M_ACL, "acl", "access control list"); static int vacl_set_acl(struct proc *p, struct vnode *vp, acl_type_t type, struct acl *aclp); static int vacl_get_acl(struct proc *p, struct vnode *vp, acl_type_t type, struct acl *aclp); static int vacl_aclcheck(struct proc *p, struct vnode *vp, acl_type_t type, struct acl *aclp); /* * Implement a version of vaccess() that understands POSIX.1e ACL semantics. * Return 0 on success, else an errno value. Should be merged into * vaccess() eventually. */ int vaccess_acl_posix1e(enum vtype type, struct acl *acl, mode_t acc_mode, struct ucred *cred, int *privused) { struct acl_entry *acl_other, *acl_mask; mode_t dac_granted; mode_t cap_granted; mode_t acl_mask_granted; int group_matched, i; /* * Look for a normal, non-privileged way to access the file/directory * as requested. If it exists, go with that. Otherwise, attempt * to use privileges granted via cap_granted. In some cases, * which privileges to use may be ambiguous due to "best match", * in which case fall back on first match for the time being. */ if (privused != NULL) *privused = 0; /* * Determine privileges now, but don't apply until we've found * a DAC match that has failed to allow access. */ #ifndef CAPABILITIES if (suser_xxx(cred, NULL, PRISON_ROOT) == 0) cap_granted = (VEXEC | VREAD | VWRITE | VADMIN); else cap_granted = 0; #else cap_granted = 0; if (type == VDIR) { if ((acc_mode & VEXEC) && !cap_check(cred, NULL, CAP_DAC_READ_SEARCH, PRISON_ROOT)) cap_granted |= VEXEC; } else { if ((acc_mode & VEXEC) && !cap_check(cred, NULL, CAP_DAC_EXECUTE, PRISON_ROOT)) cap_granted |= VEXEC; } if ((acc_mode & VREAD) && !cap_check(cred, NULL, CAP_DAC_READ_SEARCH, PRISON_ROOT)) cap_granted |= VREAD; if ((acc_mode & VWRITE) && !cap_check(cred, NULL, CAP_DAC_WRITE, PRISON_ROOT)) cap_granted |= VWRITE; if ((acc_mode & VADMIN) && !cap_check(cred, NULL, CAP_FOWNER, PRISON_ROOT)) cap_granted |= VADMIN; #endif /* CAPABILITIES */ /* * Check the owner. * Also, record locations of ACL_MASK and ACL_OTHER for reference * later if the owner doesn't match. */ acl_mask = acl_other = NULL; for (i = 0; i < acl->acl_cnt; i++) { switch (acl->acl_entry[i].ae_tag) { case ACL_USER_OBJ: if (acl->acl_entry[i].ae_id != cred->cr_uid) break; dac_granted = 0; dac_granted |= VADMIN; if (acl->acl_entry[i].ae_perm & ACL_EXECUTE) dac_granted |= VEXEC; if (acl->acl_entry[i].ae_perm & ACL_READ) dac_granted |= VREAD; if (acl->acl_entry[i].ae_perm & ACL_WRITE) dac_granted |= VWRITE; if ((acc_mode & dac_granted) == acc_mode) return (0); if ((acc_mode & (dac_granted | cap_granted)) == acc_mode) { if (privused != NULL) *privused = 1; return (0); } goto error; case ACL_MASK: acl_mask = &acl->acl_entry[i]; break; case ACL_OTHER: acl_other = &acl->acl_entry[i]; break; default: } } /* * Checks against ACL_USER, ACL_GROUP_OBJ, and ACL_GROUP fields * are masked by an ACL_MASK entry, if any. As such, first identify * the ACL_MASK field, then iterate through identifying potential * user matches, then group matches. If there is no ACL_MASK, * assume that the mask allows all requests to succeed. * Also keep track of the location of ACL_OTHER for later consumption. */ if (acl_other == NULL) { /* * XXX: This should never happen. Only properly formatted * ACLs should be passed to vaccess_acl_posix1e. * Should make this a panic post-debugging. */ printf("vaccess_acl_posix1e: ACL_OTHER missing\n"); return (EPERM); } if (acl_mask != NULL) { acl_mask_granted = 0; if (acl_mask->ae_perm & ACL_EXECUTE) acl_mask_granted |= VEXEC; if (acl_mask->ae_perm & ACL_READ) acl_mask_granted |= VREAD; if (acl_mask->ae_perm & ACL_WRITE) acl_mask_granted |= VWRITE; } else acl_mask_granted = VEXEC | VREAD | VWRITE; /* * We have to check each type even if we know ACL_MASK will reject, * as we need to know what match there might have been, and * therefore what further types we might be allowed to check. * Do the checks twice -- once without privilege, and a second time * with, if there was a match. */ /* * Check ACL_USER ACL entries. */ for (i = 0; i < acl->acl_cnt; i++) { switch (acl->acl_entry[i].ae_tag) { case ACL_USER: if (acl->acl_entry[i].ae_id != cred->cr_uid) break; dac_granted = 0; if (acl->acl_entry[i].ae_perm & ACL_EXECUTE) dac_granted |= VEXEC; if (acl->acl_entry[i].ae_perm & ACL_READ) dac_granted |= VREAD; if (acl->acl_entry[i].ae_perm & ACL_WRITE) dac_granted |= VWRITE; dac_granted &= acl_mask_granted; if ((acc_mode & dac_granted) == acc_mode) return (0); if ((acc_mode & (dac_granted | cap_granted)) == acc_mode) { if (privused != NULL) *privused = 1; return (0); } goto error; } } /* * Group match is best-match, not first-match, so find a * "best" match. Iterate across, testing each potential group * match. Make sure we keep track of whether we found a match * or not, so that we know if we can move on to ACL_OTHER. */ group_matched = 0; for (i = 0; i < acl->acl_cnt; i++) { switch (acl->acl_entry[i].ae_tag) { case ACL_GROUP_OBJ: case ACL_GROUP: if (groupmember(acl->acl_entry[i].ae_id, cred)) { dac_granted = 0; if (acl->acl_entry[i].ae_perm & ACL_EXECUTE) dac_granted |= VEXEC; if (acl->acl_entry[i].ae_perm & ACL_READ) dac_granted |= VREAD; if (acl->acl_entry[i].ae_perm & ACL_WRITE) dac_granted |= VWRITE; dac_granted &= acl_mask_granted; if ((acc_mode & dac_granted) == acc_mode) return (0); group_matched = 1; } default: } } if (group_matched == 1) { /* * There was a match, but it did not grant rights via * pure DAC. Try again, this time with privilege. */ for (i = 0; i < acl->acl_cnt; i++) { switch (acl->acl_entry[i].ae_tag) { case ACL_GROUP_OBJ: case ACL_GROUP: if (groupmember(acl->acl_entry[i].ae_id, cred)) { dac_granted = 0; if (acl->acl_entry[i].ae_perm & ACL_EXECUTE) dac_granted |= VEXEC; if (acl->acl_entry[i].ae_perm & ACL_READ) dac_granted |= VREAD; if (acl->acl_entry[i].ae_perm & ACL_WRITE) dac_granted |= VWRITE; dac_granted &= acl_mask_granted; if ((acc_mode & (dac_granted | cap_granted)) == acc_mode) { if (privused != NULL) *privused = 1; return (0); } } default: } } /* * Even with privilege, group membership was not sufficient. * Return failure. */ goto error; } /* * Fall back on ACL_OTHER. ACL_MASK is not applied to ACL_OTHER. */ dac_granted = 0; if (acl_other->ae_perm & ACL_EXECUTE) dac_granted |= VEXEC; if (acl_other->ae_perm & ACL_READ) dac_granted |= VREAD; if (acl_other->ae_perm & ACL_WRITE) dac_granted |= VWRITE; if ((acc_mode & dac_granted) == acc_mode) return (0); if ((acc_mode & (dac_granted | cap_granted)) == acc_mode) { if (privused != NULL) *privused = 1; return (0); } error: return ((acc_mode & VADMIN) ? EPERM : EACCES); } /* * For the purposes of file systems maintaining the _OBJ entries in an * inode with a mode_t field, this routine converts a mode_t entry * to an acl_perm_t. */ acl_perm_t acl_posix1e_mode_to_perm(acl_tag_t tag, mode_t mode) { acl_perm_t perm = 0; switch(tag) { case ACL_USER_OBJ: if (mode & S_IXUSR) perm |= ACL_EXECUTE; if (mode & S_IRUSR) perm |= ACL_READ; if (mode & S_IWUSR) perm |= ACL_WRITE; return (perm); case ACL_GROUP_OBJ: if (mode & S_IXGRP) perm |= ACL_EXECUTE; if (mode & S_IRGRP) perm |= ACL_READ; if (mode & S_IWGRP) perm |= ACL_WRITE; return (perm); case ACL_OTHER: if (mode & S_IXOTH) perm |= ACL_EXECUTE; if (mode & S_IROTH) perm |= ACL_READ; if (mode & S_IWOTH) perm |= ACL_WRITE; return (perm); default: printf("acl_posix1e_mode_to_perm: invalid tag (%d)\n", tag); return (0); } } /* * Given inode information (uid, gid, mode), return an acl entry of the * appropriate type. */ struct acl_entry acl_posix1e_mode_to_entry(acl_tag_t tag, uid_t uid, gid_t gid, mode_t mode) { struct acl_entry acl_entry; acl_entry.ae_tag = tag; acl_entry.ae_perm = acl_posix1e_mode_to_perm(tag, mode); switch(tag) { case ACL_USER_OBJ: acl_entry.ae_id = uid; break; case ACL_GROUP_OBJ: acl_entry.ae_id = gid; break; case ACL_OTHER: acl_entry.ae_id = 0; break; default: acl_entry.ae_id = 0; printf("acl_posix1e_mode_to_entry: invalid tag (%d)\n", tag); } return (acl_entry); } /* * Utility function to generate a file mode given appropriate ACL entries. */ mode_t acl_posix1e_perms_to_mode(struct acl_entry *acl_user_obj_entry, struct acl_entry *acl_group_obj_entry, struct acl_entry *acl_other_entry) { mode_t mode; mode = 0; if (acl_user_obj_entry->ae_perm & ACL_EXECUTE) mode |= S_IXUSR; if (acl_user_obj_entry->ae_perm & ACL_READ) mode |= S_IRUSR; if (acl_user_obj_entry->ae_perm & ACL_WRITE) mode |= S_IWUSR; if (acl_group_obj_entry->ae_perm & ACL_EXECUTE) mode |= S_IXGRP; if (acl_group_obj_entry->ae_perm & ACL_READ) mode |= S_IRGRP; if (acl_group_obj_entry->ae_perm & ACL_WRITE) mode |= S_IWGRP; if (acl_other_entry->ae_perm & ACL_EXECUTE) mode |= S_IXOTH; if (acl_other_entry->ae_perm & ACL_READ) mode |= S_IROTH; if (acl_other_entry->ae_perm & ACL_WRITE) mode |= S_IWOTH; return (mode); } /* * Perform a syntactic check of the ACL, sufficient to allow an * implementing file system to determine if it should accept this and * rely on the POSIX.1e ACL properties. */ int acl_posix1e_check(struct acl *acl) { int num_acl_user_obj, num_acl_user, num_acl_group_obj, num_acl_group; int num_acl_mask, num_acl_other, i; /* * Verify that the number of entries does not exceed the maximum * defined for acl_t. * Verify that the correct number of various sorts of ae_tags are * present: * Exactly one ACL_USER_OBJ * Exactly one ACL_GROUP_OBJ * Exactly one ACL_OTHER * If any ACL_USER or ACL_GROUP entries appear, then exactly one * ACL_MASK entry must also appear. * Verify that all ae_perm entries are in ACL_PERM_BITS. * Verify all ae_tag entries are understood by this implementation. * Note: Does not check for uniqueness of qualifier (ae_id) field. */ num_acl_user_obj = num_acl_user = num_acl_group_obj = num_acl_group = num_acl_mask = num_acl_other = 0; if (acl->acl_cnt > ACL_MAX_ENTRIES || acl->acl_cnt < 0) return (EINVAL); for (i = 0; i < acl->acl_cnt; i++) { /* * Check for a valid tag. */ switch(acl->acl_entry[i].ae_tag) { case ACL_USER_OBJ: num_acl_user_obj++; break; case ACL_GROUP_OBJ: num_acl_group_obj++; break; case ACL_USER: num_acl_user++; break; case ACL_GROUP: num_acl_group++; break; case ACL_OTHER: num_acl_other++; break; case ACL_MASK: num_acl_mask++; break; default: return (EINVAL); } /* * Check for valid perm entries. */ if ((acl->acl_entry[i].ae_perm | ACL_PERM_BITS) != ACL_PERM_BITS) return (EINVAL); } if ((num_acl_user_obj != 1) || (num_acl_group_obj != 1) || (num_acl_other != 1) || (num_acl_mask != 0 && num_acl_mask != 1)) return (EINVAL); if (((num_acl_group != 0) || (num_acl_user != 0)) && (num_acl_mask != 1)) return (EINVAL); return (0); } /* * 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 proc *p, struct vnode *vp, acl_type_t type, struct acl *aclp) { struct acl inkernacl; int error; error = copyin(aclp, &inkernacl, sizeof(struct acl)); if (error) return(error); VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE); vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p); error = VOP_SETACL(vp, type, &inkernacl, p->p_ucred, p); VOP_UNLOCK(vp, 0, p); return(error); } /* * Given a vnode, get its ACL. */ static int vacl_get_acl(struct proc *p, struct vnode *vp, acl_type_t type, struct acl *aclp) { struct acl inkernelacl; int error; VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE); vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p); error = VOP_GETACL(vp, type, &inkernelacl, p->p_ucred, p); VOP_UNLOCK(vp, 0, p); if (error == 0) error = copyout(&inkernelacl, aclp, sizeof(struct acl)); return (error); } /* * Given a vnode, delete its ACL. */ static int vacl_delete(struct proc *p, struct vnode *vp, acl_type_t type) { int error; VOP_LEASE(vp, p, p->p_ucred, LEASE_WRITE); vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p); error = VOP_SETACL(vp, ACL_TYPE_DEFAULT, 0, p->p_ucred, p); VOP_UNLOCK(vp, 0, p); return (error); } /* * Given a vnode, check whether an ACL is appropriate for it */ static int vacl_aclcheck(struct proc *p, struct vnode *vp, acl_type_t type, struct acl *aclp) { struct acl inkernelacl; int error; error = copyin(aclp, &inkernelacl, sizeof(struct acl)); if (error) return(error); error = VOP_ACLCHECK(vp, type, &inkernelacl, p->p_ucred, p); 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 __acl_get_file(struct proc *p, struct __acl_get_file_args *uap) { struct nameidata nd; int error; /* what flags are required here -- possible not LOCKLEAF? */ NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, SCARG(uap, path), p); error = namei(&nd); if (error) return(error); error = vacl_get_acl(p, nd.ni_vp, SCARG(uap, type), SCARG(uap, aclp)); NDFREE(&nd, 0); return (error); } /* * Given a file path, set an ACL for it */ int __acl_set_file(struct proc *p, struct __acl_set_file_args *uap) { struct nameidata nd; int error; NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, SCARG(uap, path), p); error = namei(&nd); if (error) return(error); error = vacl_set_acl(p, nd.ni_vp, SCARG(uap, type), SCARG(uap, aclp)); NDFREE(&nd, 0); return (error); } /* * Given a file descriptor, get an ACL for it */ int __acl_get_fd(struct proc *p, struct __acl_get_fd_args *uap) { struct file *fp; int error; error = getvnode(p->p_fd, SCARG(uap, filedes), &fp); if (error) return(error); return vacl_get_acl(p, (struct vnode *)fp->f_data, SCARG(uap, type), SCARG(uap, aclp)); } /* * Given a file descriptor, set an ACL for it */ int __acl_set_fd(struct proc *p, struct __acl_set_fd_args *uap) { struct file *fp; int error; error = getvnode(p->p_fd, SCARG(uap, filedes), &fp); if (error) return(error); return vacl_set_acl(p, (struct vnode *)fp->f_data, SCARG(uap, type), SCARG(uap, aclp)); } /* * Given a file path, delete an ACL from it. */ int __acl_delete_file(struct proc *p, struct __acl_delete_file_args *uap) { struct nameidata nd; int error; NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, SCARG(uap, path), p); error = namei(&nd); if (error) return(error); error = vacl_delete(p, nd.ni_vp, SCARG(uap, type)); NDFREE(&nd, 0); return (error); } /* * Given a file path, delete an ACL from it. */ int __acl_delete_fd(struct proc *p, struct __acl_delete_fd_args *uap) { struct file *fp; int error; error = getvnode(p->p_fd, SCARG(uap, filedes), &fp); if (error) return(error); error = vacl_delete(p, (struct vnode *)fp->f_data, SCARG(uap, type)); return (error); } /* * Given a file path, check an ACL for it */ int __acl_aclcheck_file(struct proc *p, struct __acl_aclcheck_file_args *uap) { struct nameidata nd; int error; NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, SCARG(uap, path), p); error = namei(&nd); if (error) return(error); error = vacl_aclcheck(p, nd.ni_vp, SCARG(uap, type), SCARG(uap, aclp)); NDFREE(&nd, 0); return (error); } /* * Given a file descriptor, check an ACL for it */ int __acl_aclcheck_fd(struct proc *p, struct __acl_aclcheck_fd_args *uap) { struct file *fp; int error; error = getvnode(p->p_fd, SCARG(uap, filedes), &fp); if (error) return(error); return vacl_aclcheck(p, (struct vnode *)fp->f_data, SCARG(uap, type), SCARG(uap, aclp)); }