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-rw-r--r--fs/posix_acl.c381
1 files changed, 381 insertions, 0 deletions
diff --git a/fs/posix_acl.c b/fs/posix_acl.c
new file mode 100644
index 00000000000..296480e96dd
--- /dev/null
+++ b/fs/posix_acl.c
@@ -0,0 +1,381 @@
+/*
+ * linux/fs/posix_acl.c
+ *
+ * Copyright (C) 2002 by Andreas Gruenbacher <a.gruenbacher@computer.org>
+ *
+ * Fixes from William Schumacher incorporated on 15 March 2001.
+ * (Reported by Charles Bertsch, <CBertsch@microtest.com>).
+ */
+
+/*
+ * This file contains generic functions for manipulating
+ * POSIX 1003.1e draft standard 17 ACLs.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <asm/atomic.h>
+#include <linux/fs.h>
+#include <linux/sched.h>
+#include <linux/posix_acl.h>
+#include <linux/module.h>
+
+#include <linux/errno.h>
+
+EXPORT_SYMBOL(posix_acl_alloc);
+EXPORT_SYMBOL(posix_acl_clone);
+EXPORT_SYMBOL(posix_acl_valid);
+EXPORT_SYMBOL(posix_acl_equiv_mode);
+EXPORT_SYMBOL(posix_acl_from_mode);
+EXPORT_SYMBOL(posix_acl_create_masq);
+EXPORT_SYMBOL(posix_acl_chmod_masq);
+EXPORT_SYMBOL(posix_acl_permission);
+
+/*
+ * Allocate a new ACL with the specified number of entries.
+ */
+struct posix_acl *
+posix_acl_alloc(int count, unsigned int __nocast flags)
+{
+ const size_t size = sizeof(struct posix_acl) +
+ count * sizeof(struct posix_acl_entry);
+ struct posix_acl *acl = kmalloc(size, flags);
+ if (acl) {
+ atomic_set(&acl->a_refcount, 1);
+ acl->a_count = count;
+ }
+ return acl;
+}
+
+/*
+ * Clone an ACL.
+ */
+struct posix_acl *
+posix_acl_clone(const struct posix_acl *acl, unsigned int __nocast flags)
+{
+ struct posix_acl *clone = NULL;
+
+ if (acl) {
+ int size = sizeof(struct posix_acl) + acl->a_count *
+ sizeof(struct posix_acl_entry);
+ clone = kmalloc(size, flags);
+ if (clone) {
+ memcpy(clone, acl, size);
+ atomic_set(&clone->a_refcount, 1);
+ }
+ }
+ return clone;
+}
+
+/*
+ * Check if an acl is valid. Returns 0 if it is, or -E... otherwise.
+ */
+int
+posix_acl_valid(const struct posix_acl *acl)
+{
+ const struct posix_acl_entry *pa, *pe;
+ int state = ACL_USER_OBJ;
+ unsigned int id = 0; /* keep gcc happy */
+ int needs_mask = 0;
+
+ FOREACH_ACL_ENTRY(pa, acl, pe) {
+ if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE))
+ return -EINVAL;
+ switch (pa->e_tag) {
+ case ACL_USER_OBJ:
+ if (state == ACL_USER_OBJ) {
+ id = 0;
+ state = ACL_USER;
+ break;
+ }
+ return -EINVAL;
+
+ case ACL_USER:
+ if (state != ACL_USER)
+ return -EINVAL;
+ if (pa->e_id == ACL_UNDEFINED_ID ||
+ pa->e_id < id)
+ return -EINVAL;
+ id = pa->e_id + 1;
+ needs_mask = 1;
+ break;
+
+ case ACL_GROUP_OBJ:
+ if (state == ACL_USER) {
+ id = 0;
+ state = ACL_GROUP;
+ break;
+ }
+ return -EINVAL;
+
+ case ACL_GROUP:
+ if (state != ACL_GROUP)
+ return -EINVAL;
+ if (pa->e_id == ACL_UNDEFINED_ID ||
+ pa->e_id < id)
+ return -EINVAL;
+ id = pa->e_id + 1;
+ needs_mask = 1;
+ break;
+
+ case ACL_MASK:
+ if (state != ACL_GROUP)
+ return -EINVAL;
+ state = ACL_OTHER;
+ break;
+
+ case ACL_OTHER:
+ if (state == ACL_OTHER ||
+ (state == ACL_GROUP && !needs_mask)) {
+ state = 0;
+ break;
+ }
+ return -EINVAL;
+
+ default:
+ return -EINVAL;
+ }
+ }
+ if (state == 0)
+ return 0;
+ return -EINVAL;
+}
+
+/*
+ * Returns 0 if the acl can be exactly represented in the traditional
+ * file mode permission bits, or else 1. Returns -E... on error.
+ */
+int
+posix_acl_equiv_mode(const struct posix_acl *acl, mode_t *mode_p)
+{
+ const struct posix_acl_entry *pa, *pe;
+ mode_t mode = 0;
+ int not_equiv = 0;
+
+ FOREACH_ACL_ENTRY(pa, acl, pe) {
+ switch (pa->e_tag) {
+ case ACL_USER_OBJ:
+ mode |= (pa->e_perm & S_IRWXO) << 6;
+ break;
+ case ACL_GROUP_OBJ:
+ mode |= (pa->e_perm & S_IRWXO) << 3;
+ break;
+ case ACL_OTHER:
+ mode |= pa->e_perm & S_IRWXO;
+ break;
+ case ACL_MASK:
+ mode = (mode & ~S_IRWXG) |
+ ((pa->e_perm & S_IRWXO) << 3);
+ not_equiv = 1;
+ break;
+ case ACL_USER:
+ case ACL_GROUP:
+ not_equiv = 1;
+ break;
+ default:
+ return -EINVAL;
+ }
+ }
+ if (mode_p)
+ *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
+ return not_equiv;
+}
+
+/*
+ * Create an ACL representing the file mode permission bits of an inode.
+ */
+struct posix_acl *
+posix_acl_from_mode(mode_t mode, unsigned int __nocast flags)
+{
+ struct posix_acl *acl = posix_acl_alloc(3, flags);
+ if (!acl)
+ return ERR_PTR(-ENOMEM);
+
+ acl->a_entries[0].e_tag = ACL_USER_OBJ;
+ acl->a_entries[0].e_id = ACL_UNDEFINED_ID;
+ acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6;
+
+ acl->a_entries[1].e_tag = ACL_GROUP_OBJ;
+ acl->a_entries[1].e_id = ACL_UNDEFINED_ID;
+ acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3;
+
+ acl->a_entries[2].e_tag = ACL_OTHER;
+ acl->a_entries[2].e_id = ACL_UNDEFINED_ID;
+ acl->a_entries[2].e_perm = (mode & S_IRWXO);
+ return acl;
+}
+
+/*
+ * Return 0 if current is granted want access to the inode
+ * by the acl. Returns -E... otherwise.
+ */
+int
+posix_acl_permission(struct inode *inode, const struct posix_acl *acl, int want)
+{
+ const struct posix_acl_entry *pa, *pe, *mask_obj;
+ int found = 0;
+
+ FOREACH_ACL_ENTRY(pa, acl, pe) {
+ switch(pa->e_tag) {
+ case ACL_USER_OBJ:
+ /* (May have been checked already) */
+ if (inode->i_uid == current->fsuid)
+ goto check_perm;
+ break;
+ case ACL_USER:
+ if (pa->e_id == current->fsuid)
+ goto mask;
+ break;
+ case ACL_GROUP_OBJ:
+ if (in_group_p(inode->i_gid)) {
+ found = 1;
+ if ((pa->e_perm & want) == want)
+ goto mask;
+ }
+ break;
+ case ACL_GROUP:
+ if (in_group_p(pa->e_id)) {
+ found = 1;
+ if ((pa->e_perm & want) == want)
+ goto mask;
+ }
+ break;
+ case ACL_MASK:
+ break;
+ case ACL_OTHER:
+ if (found)
+ return -EACCES;
+ else
+ goto check_perm;
+ default:
+ return -EIO;
+ }
+ }
+ return -EIO;
+
+mask:
+ for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
+ if (mask_obj->e_tag == ACL_MASK) {
+ if ((pa->e_perm & mask_obj->e_perm & want) == want)
+ return 0;
+ return -EACCES;
+ }
+ }
+
+check_perm:
+ if ((pa->e_perm & want) == want)
+ return 0;
+ return -EACCES;
+}
+
+/*
+ * Modify acl when creating a new inode. The caller must ensure the acl is
+ * only referenced once.
+ *
+ * mode_p initially must contain the mode parameter to the open() / creat()
+ * system calls. All permissions that are not granted by the acl are removed.
+ * The permissions in the acl are changed to reflect the mode_p parameter.
+ */
+int
+posix_acl_create_masq(struct posix_acl *acl, mode_t *mode_p)
+{
+ struct posix_acl_entry *pa, *pe;
+ struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
+ mode_t mode = *mode_p;
+ int not_equiv = 0;
+
+ /* assert(atomic_read(acl->a_refcount) == 1); */
+
+ FOREACH_ACL_ENTRY(pa, acl, pe) {
+ switch(pa->e_tag) {
+ case ACL_USER_OBJ:
+ pa->e_perm &= (mode >> 6) | ~S_IRWXO;
+ mode &= (pa->e_perm << 6) | ~S_IRWXU;
+ break;
+
+ case ACL_USER:
+ case ACL_GROUP:
+ not_equiv = 1;
+ break;
+
+ case ACL_GROUP_OBJ:
+ group_obj = pa;
+ break;
+
+ case ACL_OTHER:
+ pa->e_perm &= mode | ~S_IRWXO;
+ mode &= pa->e_perm | ~S_IRWXO;
+ break;
+
+ case ACL_MASK:
+ mask_obj = pa;
+ not_equiv = 1;
+ break;
+
+ default:
+ return -EIO;
+ }
+ }
+
+ if (mask_obj) {
+ mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
+ mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
+ } else {
+ if (!group_obj)
+ return -EIO;
+ group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
+ mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
+ }
+
+ *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
+ return not_equiv;
+}
+
+/*
+ * Modify the ACL for the chmod syscall.
+ */
+int
+posix_acl_chmod_masq(struct posix_acl *acl, mode_t mode)
+{
+ struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
+ struct posix_acl_entry *pa, *pe;
+
+ /* assert(atomic_read(acl->a_refcount) == 1); */
+
+ FOREACH_ACL_ENTRY(pa, acl, pe) {
+ switch(pa->e_tag) {
+ case ACL_USER_OBJ:
+ pa->e_perm = (mode & S_IRWXU) >> 6;
+ break;
+
+ case ACL_USER:
+ case ACL_GROUP:
+ break;
+
+ case ACL_GROUP_OBJ:
+ group_obj = pa;
+ break;
+
+ case ACL_MASK:
+ mask_obj = pa;
+ break;
+
+ case ACL_OTHER:
+ pa->e_perm = (mode & S_IRWXO);
+ break;
+
+ default:
+ return -EIO;
+ }
+ }
+
+ if (mask_obj) {
+ mask_obj->e_perm = (mode & S_IRWXG) >> 3;
+ } else {
+ if (!group_obj)
+ return -EIO;
+ group_obj->e_perm = (mode & S_IRWXG) >> 3;
+ }
+
+ return 0;
+}
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