diff options
Diffstat (limited to 'fs/posix_acl.c')
| -rw-r--r-- | fs/posix_acl.c | 381 |
1 files changed, 381 insertions, 0 deletions
diff --git a/fs/posix_acl.c b/fs/posix_acl.c new file mode 100644 index 0000000..296480e --- /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; +} |
