From e4eab6501fc52730ba938689c00bb1982aeb4ac1 Mon Sep 17 00:00:00 2001 From: Andreas Gruenbacher Date: Tue, 13 Oct 2009 17:08:27 +0530 Subject: [RFC PATCH 02/14] vfs: rich ACL in-memory representation and manipulation * In-memory representation (struct richacl). * Functionality a filesystem needs such as permission checking, apply mode to acl, compute mode from acl, inheritance upon file create. * Compute a mask-less acl from struct richacl that grants the same permissions. Protocols which don't understand the masks need this. * Convert to/from xattrs. Signed-off-by: Andreas Gruenbacher Signed-off-by: Aneesh Kumar K.V --- fs/Kconfig | 4 + fs/Makefile | 4 + fs/richacl_base.c | 568 +++++++++++++++++++++++++++++++ fs/richacl_compat.c | 757 +++++++++++++++++++++++++++++++++++++++++ fs/richacl_xattr.c | 146 ++++++++ include/linux/richacl.h | 208 +++++++++++ include/linux/richacl_xattr.h | 32 ++ 7 files changed, 1719 insertions(+), 0 deletions(-) create mode 100644 fs/richacl_base.c create mode 100644 fs/richacl_compat.c create mode 100644 fs/richacl_xattr.c create mode 100644 include/linux/richacl.h create mode 100644 include/linux/richacl_xattr.h diff --git a/fs/Kconfig b/fs/Kconfig index 2126078..9e80ee0 100644 --- a/fs/Kconfig +++ b/fs/Kconfig @@ -39,6 +39,10 @@ config FS_POSIX_ACL bool default n +config FS_RICHACL + bool + default n + source "fs/xfs/Kconfig" source "fs/gfs2/Kconfig" source "fs/ocfs2/Kconfig" diff --git a/fs/Makefile b/fs/Makefile index af6d047..0a046a1 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -51,6 +51,10 @@ obj-$(CONFIG_FS_POSIX_ACL) += posix_acl.o xattr_acl.o obj-$(CONFIG_NFS_COMMON) += nfs_common/ obj-$(CONFIG_GENERIC_ACL) += generic_acl.o +obj-$(CONFIG_FS_RICHACL) += richacl.o +richacl-y := richacl_base.o richacl_xattr.o \ + richacl_compat.o + obj-y += quota/ obj-$(CONFIG_PROC_FS) += proc/ diff --git a/fs/richacl_base.c b/fs/richacl_base.c new file mode 100644 index 0000000..de99340 --- /dev/null +++ b/fs/richacl_base.c @@ -0,0 +1,568 @@ +/* + * Copyright (C) 2006 Andreas Gruenbacher + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2, or (at your option) any + * later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + */ + +#include +#include +#include +#include + +MODULE_LICENSE("GPL"); + +/* + * ACL entries that have ACE4_SPECIAL_WHO set in ace->e_flags use the + * pointer values of these constants in ace->u.e_who to avoid massive + * amounts of string comparisons. + */ + +const char richace_owner_who[] = "OWNER@"; +EXPORT_SYMBOL_GPL(richace_owner_who); +const char richace_group_who[] = "GROUP@"; +EXPORT_SYMBOL_GPL(richace_group_who); +const char richace_everyone_who[] = "EVERYONE@"; +EXPORT_SYMBOL_GPL(richace_everyone_who); + +/** + * richacl_alloc - allocate an acl + * @count: number of entries + */ +struct richacl * +richacl_alloc(int count) +{ + size_t size = sizeof(struct richacl) + count * sizeof(struct richace); + struct richacl *acl = kmalloc(size, GFP_KERNEL); + + if (acl) { + memset(acl, 0, size); + atomic_set(&acl->a_refcount, 1); + acl->a_count = count; + } + return acl; +} +EXPORT_SYMBOL_GPL(richacl_alloc); + +/** + * richacl_clone - create a copy of an acl + */ +struct richacl * +richacl_clone(const struct richacl *acl) +{ + int count = acl->a_count; + size_t size = sizeof(struct richacl) + count * sizeof(struct richace); + struct richacl *dup = kmalloc(size, GFP_KERNEL); + + if (dup) { + memcpy(dup, acl, size); + atomic_set(&dup->a_refcount, 1); + } + return dup; +} + +/* + * The POSIX permissions are supersets of the below mask flags. + * + * The ACE4_READ_ATTRIBUTES and ACE4_READ_ACL flags are always granted + * in POSIX. The ACE4_SYNCHRONIZE flag has no meaning under POSIX. We + * make sure that we do not mask them if they are set, so that users who + * rely on these flags won't get confused. + */ +#define ACE4_POSIX_MODE_READ ( \ + ACE4_READ_DATA | ACE4_LIST_DIRECTORY) +#define ACE4_POSIX_MODE_WRITE ( \ + ACE4_WRITE_DATA | ACE4_ADD_FILE | \ + ACE4_APPEND_DATA | ACE4_ADD_SUBDIRECTORY | \ + ACE4_DELETE_CHILD) +#define ACE4_POSIX_MODE_EXEC ( \ + ACE4_EXECUTE) + +static int +richacl_mask_to_mode(unsigned int mask) +{ + int mode = 0; + + if (mask & ACE4_POSIX_MODE_READ) + mode |= MAY_READ; + if (mask & ACE4_POSIX_MODE_WRITE) + mode |= MAY_WRITE; + if (mask & ACE4_POSIX_MODE_EXEC) + mode |= MAY_EXEC; + + return mode; +} + +/** + * richacl_masks_to_mode - compute file mode permission bits from file masks + * + * Compute the file mode permission bits from the file masks in the acl. + */ +int +richacl_masks_to_mode(const struct richacl *acl) +{ + return richacl_mask_to_mode(acl->a_owner_mask) << 6 | + richacl_mask_to_mode(acl->a_group_mask) << 3 | + richacl_mask_to_mode(acl->a_other_mask); +} +EXPORT_SYMBOL_GPL(richacl_masks_to_mode); + +static unsigned int +richacl_mode_to_mask(mode_t mode) +{ + unsigned int mask = ACE4_POSIX_ALWAYS_ALLOWED; + + if (mode & MAY_READ) + mask |= ACE4_POSIX_MODE_READ; + if (mode & MAY_WRITE) + mask |= ACE4_POSIX_MODE_WRITE; + if (mode & MAY_EXEC) + mask |= ACE4_POSIX_MODE_EXEC; + + return mask; +} + +/** + * richacl_chmod - update the file masks to reflect the new mode + * @mode: file mode permission bits to apply to the @acl + * + * Converts the mask flags corresponding to the owner, group, and other file + * permissions and computes the file masks. Returns @acl if it already has the + * appropriate file masks, or updates the flags in a copy of @acl. Takes over + * @acl. + */ +struct richacl * +richacl_chmod(struct richacl *acl, mode_t mode) +{ + unsigned int owner_mask, group_mask, other_mask; + struct richacl *clone; + + owner_mask = richacl_mode_to_mask(mode >> 6); + group_mask = richacl_mode_to_mask(mode >> 3); + other_mask = richacl_mode_to_mask(mode); + + if (acl->a_owner_mask == owner_mask && + acl->a_group_mask == group_mask && + acl->a_other_mask == other_mask) + return acl; + + clone = richacl_clone(acl); + richacl_put(acl); + if (!clone) + return ERR_PTR(-ENOMEM); + + clone->a_owner_mask = owner_mask; + clone->a_group_mask = group_mask; + clone->a_other_mask = other_mask; + + if (richacl_write_through(&clone)) { + richacl_put(clone); + clone = ERR_PTR(-ENOMEM); + } + return clone; +} +EXPORT_SYMBOL_GPL(richacl_chmod); + +/** + * richacl_want_to_mask - convert permission want argument to a mask + * @want: @want argument of the permission inode operation + * + * When checking for append, @want is (MAY_WRITE | MAY_APPEND). + */ +unsigned int +richacl_want_to_mask(int want) +{ + unsigned int mask = 0; + + if (want & MAY_READ) + mask |= ACE4_READ_DATA; + if (want & MAY_APPEND) + mask |= ACE4_APPEND_DATA; + else if (want & MAY_WRITE) + mask |= ACE4_WRITE_DATA; + if (want & MAY_EXEC) + mask |= ACE4_EXECUTE; + + return mask; +} +EXPORT_SYMBOL_GPL(richacl_want_to_mask); + +/** + * richacl_capability_check -check for capabilities overriding read/write access + * @inode: inode to check + * @mask: requested access (ACE4_* bitmask) + * + * Capabilities other than CAP_DAC_OVERRIDE and CAP_DAC_READ_SEARCH + * must be checked separately. + */ +static inline int richacl_capability_check(struct inode *inode, + unsigned int mask) +{ + /* + * Read/write DACs are always overridable. + * Executable DACs are overridable if at least one exec bit is set. + */ + if (!(mask & (ACE4_WRITE_ACL | ACE4_WRITE_OWNER)) && + (!(mask & ACE4_EXECUTE) || + (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode))) + if (capable(CAP_DAC_OVERRIDE)) + return 0; + + /* + * Searching includes executable on directories, else just read. + */ + if (!(mask & ~(ACE4_READ_DATA | ACE4_EXECUTE)) && + (S_ISDIR(inode->i_mode) || !(mask & ACE4_EXECUTE))) + if (capable(CAP_DAC_READ_SEARCH)) + return 0; + + return -EACCES; +} + +/** + * richacl_permission - permission check algorithm with masking + * @inode: inode to check + * @acl: rich acl of the inode + * @mask: requested access (ACE4_* bitmask) + * + * Checks if the current process is granted @mask flags in @acl. With + * write-through, the OWNER@ is always granted the owner file mask, the + * GROUP@ is always granted the group file mask, and EVERYONE@ is always + * granted the other file mask. Otherwise, processes are only granted + * @mask flags which they are granted in the @acl as well as in their + * file mask. + */ +int richacl_permission(struct inode *inode, const struct richacl *acl, + unsigned int mask) +{ + const struct richace *ace; + unsigned int file_mask, requested = mask, denied = 0; + int in_owning_group = in_group_p(inode->i_gid); + int owner_or_group_class = in_owning_group; + + /* + * A process is in the + * - owner file class if it owns the file, in the + * - group file class if it is in the file's owning group or + * it matches any of the user or group entries, and in the + * - other file class otherwise. + */ + + richacl_for_each_entry(ace, acl) { + unsigned int ace_mask = ace->e_mask; + + if (richace_is_inherit_only(ace)) + continue; + if (richace_is_owner(ace)) { + if (current_fsuid() != inode->i_uid) + continue; + goto is_owner; + } else if (richace_is_group(ace)) { + if (!in_owning_group) + continue; + } else if (richace_is_unix_id(ace)) { + if (ace->e_flags & ACE4_IDENTIFIER_GROUP) { + if (!in_group_p(ace->u.e_id)) + continue; + } else { + if (current_fsuid() != ace->u.e_id) + continue; + } + } else + goto is_everyone; + + /* + * Apply the group file mask to entries other than OWNER@ and + * EVERYONE@. This is not required for correct access checking + * but ensures that we grant the same permissions as the acl + * computed by richacl_apply_masks(). + * + * For example, without this restriction, 'group@:rw::allow' + * with mode 0600 would grant rw access to owner processes + * which are also in the owning group. This cannot be expressed + * in an acl. + */ + if (richace_is_allow(ace)) + ace_mask &= acl->a_group_mask; + +is_owner: + /* The process is in the owner or group file class. */ + owner_or_group_class = 1; + +is_everyone: + /* Check which mask flags the ACE allows or denies. */ + if (richace_is_deny(ace)) + denied |= ace_mask & mask; + mask &= ~ace_mask; + + /* + * Keep going until we know which file class + * the process is in. + */ + if (!mask && owner_or_group_class) + break; + } + denied |= mask; + + /* + * Figure out which file mask applies. + * Clear write-through if the process is in the file group class but + * not in the owning group, and so the denied permissions apply. + */ + if (current_fsuid() == inode->i_uid) + file_mask = acl->a_owner_mask; + else if (in_owning_group || owner_or_group_class) + file_mask = acl->a_group_mask; + else + file_mask = acl->a_other_mask; + + denied |= requested & ~file_mask; + if (!denied) + return 0; + return richacl_capability_check(inode, requested); +} +EXPORT_SYMBOL_GPL(richacl_permission); + +/** + * richacl_generic_permission - permission check algorithm without explicit acl + * @inode: inode to check permissions for + * @mask: requested access (ACE4_* bitmask) + * + * The file mode of a file without ACL corresponds to an ACL with a single + * "EVERYONE:~0::ALLOW" entry, with file masks that correspond to the file mode + * permissions. Instead of constructing a temporary ACL and applying + * richacl_permission() to it, compute the identical result directly from + * the file mode. + */ +int richacl_generic_permission(struct inode *inode, unsigned int mask) +{ + int mode = inode->i_mode; + + if (current_fsuid() == inode->i_uid) + mode >>= 6; + else if (in_group_p(inode->i_gid)) + mode >>= 3; + if (!(mask & ~richacl_mode_to_mask(mode))) + return 0; + return richacl_capability_check(inode, mask); +} +EXPORT_SYMBOL_GPL(richacl_generic_permission); + +/* + * richace_is_same_who - do both acl entries refer to the same identifier? + */ +int +richace_is_same_who(const struct richace *a, const struct richace *b) +{ +#define WHO_FLAGS (ACE4_SPECIAL_WHO | ACE4_IDENTIFIER_GROUP) + if ((a->e_flags & WHO_FLAGS) != (b->e_flags & WHO_FLAGS)) + return 0; + if (a->e_flags & ACE4_SPECIAL_WHO) + return a->u.e_who == b->u.e_who; + else + return a->u.e_id == b->u.e_id; +#undef WHO_FLAGS +} + +/** + * richacl_set_who - set a special who value + * @ace: acl entry + * @who: who value to use + */ +int +richace_set_who(struct richace *ace, const char *who) +{ + if (!strcmp(who, richace_owner_who)) + who = richace_owner_who; + else if (!strcmp(who, richace_group_who)) + who = richace_group_who; + else if (!strcmp(who, richace_everyone_who)) + who = richace_everyone_who; + else + return -EINVAL; + + ace->u.e_who = who; + ace->e_flags |= ACE4_SPECIAL_WHO; + ace->e_flags &= ~ACE4_IDENTIFIER_GROUP; + return 0; +} +EXPORT_SYMBOL_GPL(richace_set_who); + +/** + * richacl_allowed_to_who - mask flags allowed to a specific who value + * + * Computes the mask values allowed to a specific who value, taking + * EVERYONE@ entries into account. + */ +static unsigned int +richacl_allowed_to_who(struct richacl *acl, struct richace *who) +{ + struct richace *ace; + unsigned int allowed = 0; + + richacl_for_each_entry_reverse(ace, acl) { + if (richace_is_inherit_only(ace)) + continue; + if (richace_is_same_who(ace, who) || + richace_is_everyone(ace)) { + if (richace_is_allow(ace)) + allowed |= ace->e_mask; + else if (richace_is_deny(ace)) + allowed &= ~ace->e_mask; + } + } + return allowed; +} + +/** + * richacl_compute_max_masks - compute upper bound masks + * + * Computes upper bound owner, group, and other masks so that none of + * the mask flags allowed by the acl are disabled (for any choice of the + * file owner or group membership). + */ +static void +richacl_compute_max_masks(struct richacl *acl) +{ + struct richace *ace; + + acl->a_owner_mask = 0; + acl->a_group_mask = 0; + acl->a_other_mask = 0; + + richacl_for_each_entry_reverse(ace, acl) { + if (richace_is_inherit_only(ace)) + continue; + + if (richace_is_owner(ace)) { + if (richace_is_allow(ace)) + acl->a_owner_mask |= ace->e_mask; + else if (richace_is_deny(ace)) + acl->a_owner_mask &= ~ace->e_mask; + } else if (richace_is_everyone(ace)) { + if (richace_is_allow(ace)) { + struct richace who = { + .e_flags = ACE4_SPECIAL_WHO, + .u.e_who = richace_group_who, + }; + + acl->a_other_mask |= ace->e_mask; + acl->a_group_mask |= + richacl_allowed_to_who(acl, &who); + acl->a_owner_mask |= ace->e_mask; + } else if (richace_is_deny(ace)) { + acl->a_other_mask &= ~ace->e_mask; + acl->a_group_mask &= ~ace->e_mask; + acl->a_owner_mask &= ~ace->e_mask; + } + } else { + if (richace_is_allow(ace)) { + unsigned int mask = + richacl_allowed_to_who(acl, ace); + + acl->a_group_mask |= mask; + acl->a_owner_mask |= mask; + } + } + } +} + +/** + * richacl_inherit - compute the acl a new file will inherit + * @dir_acl: acl of the containing direcory + * @mode: file type and create mode of the new file + * + * Given the containing directory's acl, this function will compute the + * acl that new files in that directory will inherit, or %NULL if + * @dir_acl does not contain acl entries inheritable by this file. + * + * Without write-through, the file masks in the returned acl are set to + * the intersection of the create mode and the maximum permissions + * allowed to each file class. With write-through, the file masks are + * set to the create mode. + */ +struct richacl * +richacl_inherit(const struct richacl *dir_acl, mode_t mode) +{ + const struct richace *dir_ace; + struct richacl *acl; + struct richace *ace; + int count = 0; + + if (S_ISDIR(mode)) { + richacl_for_each_entry(dir_ace, dir_acl) { + if (!richace_is_inheritable(dir_ace)) + continue; + count++; + } + if (!count) + return NULL; + acl = richacl_alloc(count); + if (!acl) + return ERR_PTR(-ENOMEM); + ace = acl->a_entries; + richacl_for_each_entry(dir_ace, dir_acl) { + if (!richace_is_inheritable(dir_ace)) + continue; + memcpy(ace, dir_ace, sizeof(struct richace)); + if (dir_ace->e_flags & ACE4_NO_PROPAGATE_INHERIT_ACE) + richace_clear_inheritance_flags(ace); + if ((dir_ace->e_flags & ACE4_FILE_INHERIT_ACE) && + !(dir_ace->e_flags & ACE4_DIRECTORY_INHERIT_ACE)) + ace->e_flags |= ACE4_INHERIT_ONLY_ACE; + ace++; + } + } else { + richacl_for_each_entry(dir_ace, dir_acl) { + if (!(dir_ace->e_flags & ACE4_FILE_INHERIT_ACE)) + continue; + count++; + } + if (!count) + return NULL; + acl = richacl_alloc(count); + if (!acl) + return ERR_PTR(-ENOMEM); + ace = acl->a_entries; + richacl_for_each_entry(dir_ace, dir_acl) { + if (!(dir_ace->e_flags & ACE4_FILE_INHERIT_ACE)) + continue; + memcpy(ace, dir_ace, sizeof(struct richace)); + richace_clear_inheritance_flags(ace); + ace++; + } + } + + /* The maximum max flags that the owner, group, and other classes + are allowed. */ + if (dir_acl->a_flags & ACL4_WRITE_THROUGH) { + acl->a_owner_mask = ACE4_VALID_MASK; + acl->a_group_mask = ACE4_VALID_MASK; + acl->a_other_mask = ACE4_VALID_MASK; + + mode &= ~current_umask(); + } else + richacl_compute_max_masks(acl); + + /* Apply the create mode. */ + acl->a_owner_mask &= richacl_mode_to_mask(mode >> 6); + acl->a_group_mask &= richacl_mode_to_mask(mode >> 3); + acl->a_other_mask &= richacl_mode_to_mask(mode); + + if (richacl_write_through(&acl)) { + richacl_put(acl); + return ERR_PTR(-ENOMEM); + } + + acl->a_flags = (dir_acl->a_flags & ACL4_WRITE_THROUGH); + + return acl; +} +EXPORT_SYMBOL_GPL(richacl_inherit); diff --git a/fs/richacl_compat.c b/fs/richacl_compat.c new file mode 100644 index 0000000..a985bbf --- /dev/null +++ b/fs/richacl_compat.c @@ -0,0 +1,757 @@ +/* + * Copyright (C) 2006 Andreas Gruenbacher + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2, or (at your option) any + * later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + */ + +#include +#include +#include + +/** + * struct richacl_alloc - remember how many entries are actually allocated + * @acl: acl with a_count <= @count + * @count: the actual number of entries allocated in @acl + * + * We pass around this structure while modifying an acl, so that we do + * not have to reallocate when we remove existing entries followed by + * adding new entries. + */ +struct richacl_alloc { + struct richacl *acl; + unsigned int count; +}; + +/** + * richacl_delete_entry - delete an entry in an acl + * @x: acl and number of allocated entries + * @ace: an entry in @x->acl + * + * Updates @ace so that it points to the entry before the deleted entry + * on return. (When deleting the first entry, @ace will point to the + * (non-existant) entry before the first entry). This behavior is the + * expected behavior when deleting entries while forward iterating over + * an acl. + */ +static void +richacl_delete_entry(struct richacl_alloc *x, struct richace **ace) +{ + void *end = x->acl->a_entries + x->acl->a_count; + + memmove(*ace, *ace + 1, end - (void *)(*ace + 1)); + (*ace)--; + x->acl->a_count--; +} + +/** + * richacl_insert_entry - insert an entry in an acl + * @x: acl and number of allocated entries + * @ace: entry before which the new entry shall be inserted + * + * Insert a new entry in @x->acl at position @ace, and zero-initialize + * it. This may require reallocating @x->acl. + */ +static int +richacl_insert_entry(struct richacl_alloc *x, struct richace **ace) +{ + if (x->count == x->acl->a_count) { + int n = *ace - x->acl->a_entries; + struct richacl *acl2; + + acl2 = richacl_alloc(x->acl->a_count + 1); + if (!acl2) + return -1; + acl2->a_flags = x->acl->a_flags; + acl2->a_owner_mask = x->acl->a_owner_mask; + acl2->a_group_mask = x->acl->a_group_mask; + acl2->a_other_mask = x->acl->a_other_mask; + memcpy(acl2->a_entries, x->acl->a_entries, + n * sizeof(struct richace)); + memcpy(acl2->a_entries + n + 1, *ace, + (x->acl->a_count - n) * sizeof(struct richace)); + kfree(x->acl); + x->acl = acl2; + x->count = acl2->a_count; + *ace = acl2->a_entries + n; + } else { + void *end = x->acl->a_entries + x->acl->a_count; + + memmove(*ace + 1, *ace, end - (void *)*ace); + x->acl->a_count++; + } + memset(*ace, 0, sizeof(struct richace)); + return 0; +} + +/** + * richace_change_mask - change the mask in @ace to @mask + * @x: acl and number of allocated entries + * @ace: entry to modify + * @mask: new mask for @ace + * + * Set the effective mask of @ace to @mask. This will require splitting + * off a separate acl entry if @ace is inheritable. In that case, the + * effective- only acl entry is inserted after the inheritable acl + * entry, end the inheritable acl entry is set to inheritable-only. If + * @mode is 0, either set the original acl entry to inheritable-only if + * it was inheritable, or remove it otherwise. The returned @ace points + * to the modified or inserted effective-only acl entry if that entry + * exists, to the entry that has become inheritable-only, or else to the + * previous entry in the acl. This is the expected behavior when + * modifying masks while forward iterating over an acl. + */ +static int +richace_change_mask(struct richacl_alloc *x, struct richace **ace, + unsigned int mask) +{ + if (mask && (*ace)->e_mask == mask) + return 0; + if (mask & ~ACE4_POSIX_ALWAYS_ALLOWED) { + if (richace_is_inheritable(*ace)) { + if (richacl_insert_entry(x, ace)) + return -1; + memcpy(*ace, *ace + 1, sizeof(struct richace)); + (*ace)->e_flags |= ACE4_INHERIT_ONLY_ACE; + (*ace)++; + richace_clear_inheritance_flags(*ace); + } + (*ace)->e_mask = mask; + } else { + if (richace_is_inheritable(*ace)) + (*ace)->e_flags |= ACE4_INHERIT_ONLY_ACE; + else + richacl_delete_entry(x, ace); + } + return 0; +} + +/** + * richacl_move_everyone_aces_down - move everyone@ acl entries to the end + * @x: acl and number of allocated entries + * + * Move all everyone acl entries to the bottom of the acl so that only a + * single everyone@ allow acl entry remains at the end, and update the + * mask fields of all acl entries on the way. If everyone@ is not + * granted any permissions, no empty everyone@ acl entry is inserted. + * + * This transformation does not modify the permissions that the acl + * grants, but we need it to simplify successive transformations. + */ +static int +richacl_move_everyone_aces_down(struct richacl_alloc *x) +{ + struct richace *ace; + unsigned int allowed = 0, denied = 0; + + richacl_for_each_entry(ace, x->acl) { + if (richace_is_inherit_only(ace)) + continue; + if (richace_is_everyone(ace)) { + if (richace_is_allow(ace)) + allowed |= (ace->e_mask & ~denied); + else if (richace_is_deny(ace)) + denied |= (ace->e_mask & ~allowed); + else + continue; + if (richace_change_mask(x, &ace, 0)) + return -1; + } else { + if (richace_is_allow(ace)) { + if (richace_change_mask(x, &ace, allowed | + (ace->e_mask & ~denied))) + return -1; + } else if (richace_is_deny(ace)) { + if (richace_change_mask(x, &ace, denied | + (ace->e_mask & ~allowed))) + return -1; + } + } + } + if (allowed & ~ACE4_POSIX_ALWAYS_ALLOWED) { + struct richace *last_ace = ace - 1; + + if (richace_is_everyone(last_ace) && + richace_is_allow(last_ace) && + richace_is_inherit_only(last_ace) && + last_ace->e_mask == allowed) + last_ace->e_flags &= ~ACE4_INHERIT_ONLY_ACE; + else { + if (richacl_insert_entry(x, &ace)) + return -1; + ace->e_type = ACE4_ACCESS_ALLOWED_ACE_TYPE; + ace->e_flags = ACE4_SPECIAL_WHO; + ace->e_mask = allowed; + ace->u.e_who = richace_everyone_who; + } + } + return 0; +} + +/** + * __richacl_propagate_everyone - propagate everyone@ mask flags up for @who + * @x: acl and number of allocated entries + * @who: identifier to propagate mask flags for + * @allow: mask flags to propagate up + * + * Propagate mask flags from the trailing everyone@ allow acl entry up + * for the specified @who. + * + * The idea here is to precede the trailing EVERYONE@ ALLOW entry by an + * additional @who ALLOW entry, but with the following optimizations: + * (1) we don't bother setting any flags in the new @who ALLOW entry + * that has already been allowed or denied by a previous @who entry, (2) + * we merge the new @who entry with a previous @who entry if there is + * such a previous @who entry and there are no intervening DENY entries + * with mask flags that overlap the flags we care about. + */ +static int +__richacl_propagate_everyone(struct richacl_alloc *x, struct richace *who, + unsigned int allow) +{ + struct richace *allow_last = NULL, *ace; + + /* Remove the mask flags from allow that are already determined for + this who value, and figure out if there is an ALLOW entry for + this who value that is "reachable" from the trailing EVERYONE@ + ALLOW ACE. */ + richacl_for_each_entry(ace, x->acl) { + if (richace_is_inherit_only(ace)) + continue; + if (richace_is_allow(ace)) { + if (richace_is_same_who(ace, who)) { + allow &= ~ace->e_mask; + allow_last = ace; + } + } else if (richace_is_deny(ace)) { + if (richace_is_same_who(ace, who)) + allow &= ~ace->e_mask; + if (allow & ace->e_mask) + allow_last = NULL; + } + } + + if (allow) { + if (allow_last) + return richace_change_mask(x, &allow_last, + allow_last->e_mask | allow); + else { + struct richace who_copy; + + ace = x->acl->a_entries + x->acl->a_count - 1; + memcpy(&who_copy, who, sizeof(struct richace)); + if (richacl_insert_entry(x, &ace)) + return -1; + memcpy(ace, &who_copy, sizeof(struct richace)); + ace->e_type = ACE4_ACCESS_ALLOWED_ACE_TYPE; + richace_clear_inheritance_flags(ace); + ace->e_mask = allow; + } + } + return 0; +} + +/** + * richacl_propagate_everyone - propagate everyone@ mask flags up the acl + * @x: acl and number of allocated entries + * + * Make sure for owner@, group@, and all other users, groups, and + * special identifiers that they are allowed or denied all permissions + * that are granted be the trailing everyone@ acl entry. If they are + * not, try to add the missing permissions to existing allow acl entries + * for those users, or introduce additional acl entries if that is not + * possible. + * + * We do this so that no mask flags will get lost when finally applying + * the file masks to the acl entries: otherwise, with an other file mask + * that is more restrictive than the owner and/or group file mask, mask + * flags that were allowed to processes in the owner and group classes + * and that the other mask denies would be lost. For example, the + * following two acls show the problem when mode 0664 is applied to + * them: + * + * masking without propagation (wrong) + * =========================================================== + * joe:r::allow => joe:r::allow + * everyone@:rwx::allow => everyone@:r::allow + * ----------------------------------------------------------- + * joe:w::deny => joe:w::deny + * everyone@:rwx::allow everyone@:r::allow + * + * Note that the permissions of joe end up being more restrictive than + * what the acl would allow when first computing the allowed flags and + * then applying the respective mask. With propagation of permissions, + * we get: + * + * masking after propagation (correct) + * =========================================================== + * joe:r::allow => joe:rw::allow + * owner@:rw::allow + * group@:rw::allow + * everyone@:rwx::allow everyone@:r::allow + * ----------------------------------------------------------- + * joe:w::deny => owner@:x::deny + * joe:w::deny + * owner@:rw::allow + * owner@:rw::allow + * joe:r::allow + * everyone@:rwx::allow everyone@:r::allow + * + * The examples show the acls that would result from propagation with no + * masking performed. In fact, we do apply the respective mask to the + * acl entries before computing the propagation because this will save + * us from adding acl entries that would end up with empty mask fields + * after applying the masks. + * + * It is ensured that no more than one entry will be inserted for each + * who value, no matter how many entries each who value has already. + */ +static int +richacl_propagate_everyone(struct richacl_alloc *x) +{ + int write_through = (x->acl->a_flags & ACL4_WRITE_THROUGH); + struct richace who = { .e_flags = ACE4_SPECIAL_WHO }; + struct richace *ace; + unsigned int owner_allow, group_allow; + int retval; + + if (!((x->acl->a_owner_mask | x->acl->a_group_mask) & + ~x->acl->a_other_mask)) + return 0; + if (!x->acl->a_count) + return 0; + ace = x->acl->a_entries + x->acl->a_count - 1; + if (richace_is_inherit_only(ace) || !richace_is_everyone(ace)) + return 0; + if (!(ace->e_mask & ~x->acl->a_other_mask)) { + /* None of the allowed permissions will get masked. */ + return 0; + } + owner_allow = ace->e_mask & x->acl->a_owner_mask; + group_allow = ace->e_mask & x->acl->a_group_mask; + + /* Propagate everyone@ permissions through to owner@. */ + if (owner_allow && !write_through && + (x->acl->a_owner_mask & ~x->acl->a_other_mask)) { + who.u.e_who = richace_owner_who; + retval = __richacl_propagate_everyone(x, &who, owner_allow); + if (retval) + return -1; + } + + if (group_allow && (x->acl->a_group_mask & ~x->acl->a_other_mask)) { + int n; + + if (!write_through) { + /* Propagate everyone@ permissions through to group@. */ + who.u.e_who = richace_group_who; + retval = __richacl_propagate_everyone(x, &who, + group_allow); + if (retval) + return -1; + } + + /* Start from the entry before the trailing EVERYONE@ ALLOW + entry. We will not hit EVERYONE@ entries in the loop. */ + for (n = x->acl->a_count - 2; n != -1; n--) { + ace = x->acl->a_entries + n; + + if (richace_is_inherit_only(ace) || + richace_is_owner(ace) || + richace_is_group(ace)) + continue; + if (richace_is_allow(ace) || richace_is_deny(ace)) { + /* Any inserted entry will end up below the + current entry. */ + retval = __richacl_propagate_everyone(x, ace, + group_allow); + if (retval) + return -1; + } + } + } + return 0; +} + +/** + * __richacl_apply_masks - apply the masks to the acl entries + * @x: acl and number of allocated entries + * + * Apply the owner file mask to owner@ entries, the intersection of the + * group and other file masks to everyone@ entries, and the group file + * mask to all other entries. + */ +static int +__richacl_apply_masks(struct richacl_alloc *x) +{ + struct richace *ace; + + richacl_for_each_entry(ace, x->acl) { + unsigned int mask; + + if (richace_is_inherit_only(ace) || !richace_is_allow(ace)) + continue; + if (richace_is_owner(ace)) + mask = x->acl->a_owner_mask; + else if (richace_is_everyone(ace)) + mask = x->acl->a_other_mask; + else + mask = x->acl->a_group_mask; + if (richace_change_mask(x, &ace, ace->e_mask & mask)) + return -1; + } + return 0; +} + +/** + * richacl_max_allowed - maximum mask flags that anybody is allowed + */ +static unsigned int +richacl_max_allowed(struct richacl *acl) +{ + struct richace *ace; + unsigned int allowed = 0; + + richacl_for_each_entry_reverse(ace, acl) { + if (richace_is_inherit_only(ace)) + continue; + if (richace_is_allow(ace)) + allowed |= ace->e_mask; + else if (richace_is_deny(ace)) { + if (richace_is_everyone(ace)) + allowed &= ~ace->e_mask; + } + } + return allowed; +} + +/** + * richacl_isolate_owner_class - limit the owner class to the owner file mask + * @x: acl and number of allocated entries + * + * Make sure the owner class (owner@) is granted no more than the owner + * mask by first checking which permissions anyone is granted, and then + * denying owner@ all permissions beyond that. + */ +static int +richacl_isolate_owner_class(struct richacl_alloc *x) +{ + struct richace *ace; + unsigned int allowed = 0; + + allowed = richacl_max_allowed(x->acl); + if (allowed & ~x->acl->a_owner_mask) { + /* Figure out if we can update an existig OWNER@ DENY entry. */ + richacl_for_each_entry(ace, x->acl) { + if (richace_is_inherit_only(ace)) + continue; + if (richace_is_deny(ace)) { + if (richace_is_owner(ace)) + break; + } else if (richace_is_allow(ace)) { + ace = x->acl->a_entries + x->acl->a_count; + break; + } + } + if (ace != x->acl->a_entries + x->acl->a_count) { + if (richace_change_mask(x, &ace, ace->e_mask | + (allowed & ~x->acl->a_owner_mask))) + return -1; + } else { + /* Insert an owner@ deny entry at the front. */ + ace = x->acl->a_entries; + if (richacl_insert_entry(x, &ace)) + return -1; + ace->e_type = ACE4_ACCESS_DENIED_ACE_TYPE; + ace->e_flags = ACE4_SPECIAL_WHO; + ace->e_mask = allowed & ~x->acl->a_owner_mask; + ace->u.e_who = richace_owner_who; + } + } + return 0; +} + +/** + * __richacl_isolate_who - isolate entry from EVERYONE@ ALLOW entry + * @x: acl and number of allocated entries + * @who: identifier to isolate + * @deny: mask flags this identifier should not be allowed + * + * Make sure that @who is not allowed any mask flags in @deny by checking + * which mask flags this identifier is allowed, and adding excess allowed + * mask flags to an existing DENY entry before the trailing EVERYONE@ ALLOW + * entry, or inserting such an entry. + */ +static int +__richacl_isolate_who(struct richacl_alloc *x, struct richace *who, + unsigned int deny) +{ + struct richace *ace; + unsigned int allowed = 0, n; + + /* Compute the mask flags granted to this who value. */ + richacl_for_each_entry_reverse(ace, x->acl) { + if (richace_is_inherit_only(ace)) + continue; + if (richace_is_same_who(ace, who)) { + if (richace_is_allow(ace)) + allowed |= ace->e_mask; + else if (richace_is_deny(ace)) + allowed &= ~ace->e_mask; + deny &= ~ace->e_mask; + } + } + if (!deny) + return 0; + + /* Figure out if we can update an existig DENY entry. Start + from the entry before the trailing EVERYONE@ ALLOW entry. We + will not hit EVERYONE@ entries in the loop. */ + for (n = x->acl->a_count - 2; n != -1; n--) { + ace = x->acl->a_entries + n; + if (richace_is_inherit_only(ace)) + continue; + if (richace_is_deny(ace)) { + if (richace_is_same_who(ace, who)) + break; + } else if (richace_is_allow(ace) && + (ace->e_mask & deny)) { + n = -1; + break; + } + } + if (n != -1) { + if (richace_change_mask(x, &ace, ace->e_mask | deny)) + return -1; + } else { + /* Insert a eny entry before the trailing EVERYONE@ DENY + entry. */ + struct richace who_copy; + + ace = x->acl->a_entries + x->acl->a_count - 1; + memcpy(&who_copy, who, sizeof(struct richace)); + if (richacl_insert_entry(x, &ace)) + return -1; + memcpy(ace, &who_copy, sizeof(struct richace)); + ace->e_type = ACE4_ACCESS_DENIED_ACE_TYPE; + richace_clear_inheritance_flags(ace); + ace->e_mask = deny; + } + return 0; +} + +/** + * richacl_isolate_group_class - limit the group class to the group file mask + * @x: acl and number of allocated entries + * + * Make sure the group class (all entries except owner@ and everyone@) is + * granted no more than the group mask by inserting DENY entries for group + * class entries where necessary. + */ +static int +richacl_isolate_group_class(struct richacl_alloc *x) +{ + struct richace who = { + .e_flags = ACE4_SPECIAL_WHO, + .u.e_who = richace_group_who, + }; + struct richace *ace; + unsigned int deny; + + if (!x->acl->a_count) + return 0; + ace = x->acl->a_entries + x->acl->a_count - 1; + if (richace_is_inherit_only(ace) || !richace_is_everyone(ace)) + return 0; + deny = ace->e_mask & ~x->acl->a_group_mask; + + if (deny) { + unsigned int n; + + if (__richacl_isolate_who(x, &who, deny)) + return -1; + + /* Start from the entry before the trailing EVERYONE@ ALLOW + entry. We will not hit EVERYONE@ entries in the loop. */ + for (n = x->acl->a_count - 2; n != -1; n--) { + ace = x->acl->a_entries + n; + + if (richace_is_inherit_only(ace) || + richace_is_owner(ace) || + richace_is_group(ace)) + continue; + if (__richacl_isolate_who(x, ace, deny)) + return -1; + } + } + return 0; +} + +/** + * __richacl_write_through - grant the full masks to owner@, group@, everyone@ + * + * Make sure that owner, group@, and everyone@ are allowed the full mask + * permissions, and not only the permissions granted both by the acl and + * the masks. + */ +static int +__richacl_write_through(struct richacl_alloc *x) +{ + struct richace *ace; + unsigned int allowed; + + /* Remove all owner@ and group@ ACEs: we re-insert them at the + top. */ + richacl_for_each_entry(ace, x->acl) { + if (richace_is_inherit_only(ace)) + continue; + if ((richace_is_owner(ace) || richace_is_group(ace)) && + richace_change_mask(x, &ace, 0)) + return -1; + } + + /* Insert the everyone@ allow entry at the end, or update the + existing entry. */ + allowed = x->acl->a_other_mask; + if (allowed & ~ACE4_POSIX_ALWAYS_ALLOWED) { + ace = x->acl->a_entries + x->acl->a_count - 1; + if (x->acl->a_count && richace_is_everyone(ace) && + !richace_is_inherit_only(ace)) { + if (richace_change_mask(x, &ace, allowed)) + return -1; + } else { + ace = x->acl->a_entries + x->acl->a_count; + if (richacl_insert_entry(x, &ace)) + return -1; + ace->e_type = ACE4_ACCESS_ALLOWED_ACE_TYPE; + ace->e_flags = ACE4_SPECIAL_WHO; + ace->e_mask = allowed; + ace->u.e_who = richace_everyone_who; + } + } + + /* Compute the permissions that owner@ and group@ are already granted + though the everyone@ allow entry at the end. Note that the acl + contains no owner@ or group@ entries at this point. */ + allowed = 0; + richacl_for_each_entry_reverse(ace, x->acl) { + if (richace_is_inherit_only(ace)) + continue; + if (richace_is_allow(ace)) { + if (richace_is_everyone(ace)) + allowed |= ace->e_mask; + } else if (richace_is_deny(ace)) + allowed &= ~ace->e_mask; + } + + /* Insert the appropriate group@ allow entry at the front. */ + if (x->acl->a_group_mask & ~allowed) { + ace = x->acl->a_entries; + if (richacl_insert_entry(x, &ace)) + return -1; + ace->e_type = ACE4_ACCESS_ALLOWED_ACE_TYPE; + ace->e_flags = ACE4_SPECIAL_WHO; + ace->e_mask = x->acl->a_group_mask /*& ~allowed*/; + ace->u.e_who = richace_group_who; + } + + /* Insert the appropriate owner@ allow entry at the front. */ + if (x->acl->a_owner_mask & ~allowed) { + ace = x->acl->a_entries; + if (richacl_insert_entry(x, &ace)) + return -1; + ace->e_type = ACE4_ACCESS_ALLOWED_ACE_TYPE; + ace->e_flags = ACE4_SPECIAL_WHO; + ace->e_mask = x->acl->a_owner_mask /*& ~allowed*/; + ace->u.e_who = richace_owner_who; + } + + /* Insert the appropriate owner@ deny entry at the front. */ + allowed = richacl_max_allowed(x->acl); + if (allowed & ~x->acl->a_owner_mask) { + richacl_for_each_entry(ace, x->acl) { + if (richace_is_inherit_only(ace)) + continue; + if (richace_is_allow(ace)) { + ace = x->acl->a_entries + x->acl->a_count; + break; + } + if (richace_is_deny(ace) && richace_is_owner(ace)) + break; + } + if (ace != x->acl->a_entries + x->acl->a_count) { + if (richace_change_mask(x, &ace, ace->e_mask | + (allowed & ~x->acl->a_owner_mask))) + return -1; + } else { + ace = x->acl->a_entries; + if (richacl_insert_entry(x, &ace)) + return -1; + ace->e_type = ACE4_ACCESS_DENIED_ACE_TYPE; + ace->e_flags = ACE4_SPECIAL_WHO; + ace->e_mask = allowed & ~x->acl->a_owner_mask; + ace->u.e_who = richace_owner_who; + } + } + + return 0; +} + +/** + * richacl_apply_masks - apply the masks to the acl + * + * Apply the masks so that the acl allows no more flags than the + * intersection between the flags that the original acl allows and the + * mask matching the process. + * + * Note: this algorithm may push the number of entries in the acl above + * ACL4_XATTR_MAX_COUNT, so a read-modify-write cycle would fail. + */ +int +richacl_apply_masks(struct richacl **acl) +{ + struct richacl_alloc x = { + .acl = *acl, + .count = (*acl)->a_count, + }; + int retval = 0; + + if (richacl_move_everyone_aces_down(&x) || + richacl_propagate_everyone(&x) || + __richacl_apply_masks(&x) || + richacl_isolate_owner_class(&x) || + richacl_isolate_group_class(&x)) + retval = -ENOMEM; + + *acl = x.acl; + return retval; +} +EXPORT_SYMBOL_GPL(richacl_apply_masks); + +int richacl_write_through(struct richacl **acl) +{ + struct richacl_alloc x = { + .acl = *acl, + .count = (*acl)->a_count, + }; + int retval = 0; + + if (!((*acl)->a_flags & ACL4_WRITE_THROUGH)) + goto out; + + if (richacl_move_everyone_aces_down(&x) || + richacl_propagate_everyone(&x) || + __richacl_write_through(&x)) + retval = -ENOMEM; + + *acl = x.acl; +out: + return retval; +} diff --git a/fs/richacl_xattr.c b/fs/richacl_xattr.c new file mode 100644 index 0000000..4c04417 --- /dev/null +++ b/fs/richacl_xattr.c @@ -0,0 +1,146 @@ +/* + * Copyright (C) 2006 Andreas Gruenbacher + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2, or (at your option) any + * later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + */ + +#include +#include +#include +#include +#include + +MODULE_LICENSE("GPL"); + +struct richacl * +richacl_from_xattr(const void *value, size_t size) +{ + const struct richacl_xattr *xattr_acl = value; + const struct richace_xattr *xattr_ace = (void *)(xattr_acl + 1); + struct richacl *acl; + struct richace *ace; + int count; + + if (size < sizeof(struct richacl_xattr) || + xattr_acl->a_version != ACL4_XATTR_VERSION || + (xattr_acl->a_flags & ~ACL4_VALID_FLAGS)) + return ERR_PTR(-EINVAL); + + count = be16_to_cpu(xattr_acl->a_count); + if (count > ACL4_XATTR_MAX_COUNT) + return ERR_PTR(-EINVAL); + + acl = richacl_alloc(count); + if (!acl) + return ERR_PTR(-ENOMEM); + + acl->a_flags = xattr_acl->a_flags; + acl->a_owner_mask = be32_to_cpu(xattr_acl->a_owner_mask); + if (acl->a_owner_mask & ~ACE4_VALID_MASK) + goto fail_einval; + acl->a_group_mask = be32_to_cpu(xattr_acl->a_group_mask); + if (acl->a_group_mask & ~ACE4_VALID_MASK) + goto fail_einval; + acl->a_other_mask = be32_to_cpu(xattr_acl->a_other_mask); + if (acl->a_other_mask & ~ACE4_VALID_MASK) + goto fail_einval; + + richacl_for_each_entry(ace, acl) { + const char *who = (void *)(xattr_ace + 1), *end; + ssize_t used = (void *)who - value; + + if (used > size) + goto fail_einval; + end = memchr(who, 0, size - used); + if (!end) + goto fail_einval; + + ace->e_type = be16_to_cpu(xattr_ace->e_type); + ace->e_flags = be16_to_cpu(xattr_ace->e_flags); + ace->e_mask = be32_to_cpu(xattr_ace->e_mask); + ace->u.e_id = be32_to_cpu(xattr_ace->e_id); + + if (ace->e_flags & ~ACE4_VALID_FLAGS) { + memset(ace, 0, sizeof(struct richace)); + goto fail_einval; + } + if (ace->e_type > ACE4_ACCESS_DENIED_ACE_TYPE || + (ace->e_mask & ~ACE4_VALID_MASK)) + goto fail_einval; + + if (who == end) { + if (ace->u.e_id == -1) + goto fail_einval; /* uid/gid needed */ + } else if (richace_set_who(ace, who)) + goto fail_einval; + + xattr_ace = (void *)who + ALIGN(end - who + 1, 4); + } + + return acl; + +fail_einval: + richacl_put(acl); + return ERR_PTR(-EINVAL); +} +EXPORT_SYMBOL_GPL(richacl_from_xattr); + +size_t +richacl_xattr_size(const struct richacl *acl) +{ + size_t size = sizeof(struct richacl_xattr); + const struct richace *ace; + + richacl_for_each_entry(ace, acl) { + size += sizeof(struct richace_xattr) + + (richace_is_unix_id(ace) ? 4 : + ALIGN(strlen(ace->u.e_who) + 1, 4)); + } + return size; +} +EXPORT_SYMBOL_GPL(richacl_xattr_size); + +void +richacl_to_xattr(const struct richacl *acl, void *buffer) +{ + struct richacl_xattr *xattr_acl = buffer; + struct richace_xattr *xattr_ace; + const struct richace *ace; + + xattr_acl->a_version = ACL4_XATTR_VERSION; + xattr_acl->a_flags = acl->a_flags; + xattr_acl->a_count = cpu_to_be16(acl->a_count); + + xattr_acl->a_owner_mask = cpu_to_be32(acl->a_owner_mask); + xattr_acl->a_group_mask = cpu_to_be32(acl->a_group_mask); + xattr_acl->a_other_mask = cpu_to_be32(acl->a_other_mask); + + xattr_ace = (void *)(xattr_acl + 1); + richacl_for_each_entry(ace, acl) { + xattr_ace->e_type = cpu_to_be16(ace->e_type); + xattr_ace->e_flags = cpu_to_be16(ace->e_flags & + ACE4_VALID_FLAGS); + xattr_ace->e_mask = cpu_to_be32(ace->e_mask); + if (richace_is_unix_id(ace)) { + xattr_ace->e_id = cpu_to_be32(ace->u.e_id); + memset(xattr_ace->e_who, 0, 4); + xattr_ace = (void *)xattr_ace->e_who + 4; + } else { + int sz = ALIGN(strlen(ace->u.e_who) + 1, 4); + + xattr_ace->e_id = cpu_to_be32(-1); + memset(xattr_ace->e_who + sz - 4, 0, 4); + strcpy(xattr_ace->e_who, ace->u.e_who); + xattr_ace = (void *)xattr_ace->e_who + sz; + } + } +} +EXPORT_SYMBOL_GPL(richacl_to_xattr); diff --git a/include/linux/richacl.h b/include/linux/richacl.h new file mode 100644 index 0000000..a2b4bd0 --- /dev/null +++ b/include/linux/richacl.h @@ -0,0 +1,208 @@ +#ifndef __RICHACL_H +#define __RICHACL_H +#include + +struct richace { + unsigned short e_type; + unsigned short e_flags; + unsigned int e_mask; + union { + unsigned int e_id; + const char *e_who; + } u; +}; + +struct richacl { + atomic_t a_refcount; + unsigned int a_owner_mask; + unsigned int a_group_mask; + unsigned int a_other_mask; + unsigned short a_count; + unsigned short a_flags; + struct richace a_entries[0]; +}; + +#define richacl_for_each_entry(_ace, _acl) \ + for (_ace = _acl->a_entries; \ + _ace != _acl->a_entries + _acl->a_count; \ + _ace++) + +#define richacl_for_each_entry_reverse(_ace, _acl) \ + for (_ace = _acl->a_entries + _acl->a_count - 1; \ + _ace != _acl->a_entries - 1; \ + _ace--) + +/* a_flags values */ +#define ACL4_WRITE_THROUGH 0x40 + +#define ACL4_VALID_FLAGS \ + ACL4_WRITE_THROUGH + +/* e_type values */ +#define ACE4_ACCESS_ALLOWED_ACE_TYPE 0x0000 +#define ACE4_ACCESS_DENIED_ACE_TYPE 0x0001 +/*#define ACE4_SYSTEM_AUDIT_ACE_TYPE 0x0002*/ +/*#define ACE4_SYSTEM_ALARM_ACE_TYPE 0x0003*/ + +/* e_flags bitflags */ +#define ACE4_FILE_INHERIT_ACE 0x0001 +#define ACE4_DIRECTORY_INHERIT_ACE 0x0002 +#define ACE4_NO_PROPAGATE_INHERIT_ACE 0x0004 +#define ACE4_INHERIT_ONLY_ACE 0x0008 +/*#define ACE4_SUCCESSFUL_ACCESS_ACE_FLAG 0x0010*/ +/*#define ACE4_FAILED_ACCESS_ACE_FLAG 0x0020*/ +#define ACE4_IDENTIFIER_GROUP 0x0040 +/* in-memory representation only */ +#define ACE4_SPECIAL_WHO 0x4000 + +#define ACE4_VALID_FLAGS ( \ + ACE4_FILE_INHERIT_ACE | \ + ACE4_DIRECTORY_INHERIT_ACE | \ + ACE4_NO_PROPAGATE_INHERIT_ACE | \ + ACE4_INHERIT_ONLY_ACE | \ + ACE4_IDENTIFIER_GROUP) + +/* e_mask bitflags */ +#define ACE4_READ_DATA 0x00000001 +#define ACE4_LIST_DIRECTORY 0x00000001 +#define ACE4_WRITE_DATA 0x00000002 +#define ACE4_ADD_FILE 0x00000002 +#define ACE4_APPEND_DATA 0x00000004 +#define ACE4_ADD_SUBDIRECTORY 0x00000004 +#define ACE4_READ_NAMED_ATTRS 0x00000008 +#define ACE4_WRITE_NAMED_ATTRS 0x00000010 +#define ACE4_EXECUTE 0x00000020 +#define ACE4_DELETE_CHILD 0x00000040 +#define ACE4_READ_ATTRIBUTES 0x00000080 +#define ACE4_WRITE_ATTRIBUTES 0x00000100 +#define ACE4_DELETE 0x00010000 +#define ACE4_READ_ACL 0x00020000 +#define ACE4_WRITE_ACL 0x00040000 +#define ACE4_WRITE_OWNER 0x00080000 +#define ACE4_SYNCHRONIZE 0x00100000 + +#define ACE4_VALID_MASK ( \ + ACE4_READ_DATA | ACE4_LIST_DIRECTORY | \ + ACE4_WRITE_DATA | ACE4_ADD_FILE | \ + ACE4_APPEND_DATA | ACE4_ADD_SUBDIRECTORY | \ + ACE4_READ_NAMED_ATTRS | \ + ACE4_WRITE_NAMED_ATTRS | \ + ACE4_EXECUTE | \ + ACE4_DELETE_CHILD | \ + ACE4_READ_ATTRIBUTES | \ + ACE4_WRITE_ATTRIBUTES | \ + ACE4_DELETE | \ + ACE4_READ_ACL | \ + ACE4_WRITE_ACL | \ + ACE4_WRITE_OWNER | \ + ACE4_SYNCHRONIZE) + +#define ACE4_POSIX_ALWAYS_ALLOWED ( \ + ACE4_SYNCHRONIZE | \ + ACE4_READ_ATTRIBUTES | \ + ACE4_READ_ACL) +/* + * Duplicate an RICHACL handle. + */ +static inline struct richacl * +richacl_get(struct richacl *acl) +{ + if (acl) + atomic_inc(&acl->a_refcount); + return acl; +} + +/* + * Free an RICHACL handle + */ +static inline void +richacl_put(struct richacl *acl) +{ + if (acl && atomic_dec_and_test(&acl->a_refcount)) + kfree(acl); +} + +/* Special e_who identifiers: we use these pointer values in comparisons + instead of strcmp for efficiency. */ + +extern const char richace_owner_who[]; +extern const char richace_group_who[]; +extern const char richace_everyone_who[]; + +static inline int +richace_is_owner(const struct richace *ace) +{ + return (ace->e_flags & ACE4_SPECIAL_WHO) && + ace->u.e_who == richace_owner_who; +} + +static inline int +richace_is_group(const struct richace *ace) +{ + return (ace->e_flags & ACE4_SPECIAL_WHO) && + ace->u.e_who == richace_group_who; +} + +static inline int +richace_is_everyone(const struct richace *ace) +{ + return (ace->e_flags & ACE4_SPECIAL_WHO) && + ace->u.e_who == richace_everyone_who; +} + +static inline int +richace_is_unix_id(const struct richace *ace) +{ + return !(ace->e_flags & ACE4_SPECIAL_WHO); +} + +static inline int +richace_is_inherit_only(const struct richace *ace) +{ + return ace->e_flags & ACE4_INHERIT_ONLY_ACE; +} + +static inline int +richace_is_inheritable(const struct richace *ace) +{ + return ace->e_flags & (ACE4_FILE_INHERIT_ACE | + ACE4_DIRECTORY_INHERIT_ACE); +} + +static inline void +richace_clear_inheritance_flags(struct richace *ace) +{ + ace->e_flags &= ~(ACE4_FILE_INHERIT_ACE | + ACE4_DIRECTORY_INHERIT_ACE | + ACE4_NO_PROPAGATE_INHERIT_ACE | + ACE4_INHERIT_ONLY_ACE); +} + +static inline int +richace_is_allow(const struct richace *ace) +{ + return ace->e_type == ACE4_ACCESS_ALLOWED_ACE_TYPE; +} + +static inline int +richace_is_deny(const struct richace *ace) +{ + return ace->e_type == ACE4_ACCESS_DENIED_ACE_TYPE; +} + +extern struct richacl *richacl_alloc(int count); +extern struct richacl *richacl_clone(const struct richacl *acl); + +extern unsigned int richacl_want_to_mask(int want); +extern int richacl_permission(struct inode *, + const struct richacl *, unsigned int); +extern int richacl_generic_permission(struct inode *, unsigned int); +extern int richace_is_same_who(const struct richace *, const struct richace *); +extern int richace_set_who(struct richace *ace, const char *who); +extern struct richacl *richacl_inherit(const struct richacl *, mode_t); +extern int richacl_masks_to_mode(const struct richacl *); +extern struct richacl *richacl_chmod(struct richacl *, mode_t); +extern int richacl_apply_masks(struct richacl **acl); +extern int richacl_write_through(struct richacl **acl); + +#endif /* __RICHACL_H */ diff --git a/include/linux/richacl_xattr.h b/include/linux/richacl_xattr.h new file mode 100644 index 0000000..5a75284 --- /dev/null +++ b/include/linux/richacl_xattr.h @@ -0,0 +1,32 @@ +#ifndef __RICHACL_XATTR_H +#define __RICHACL_XATTR_H + +#include + +#define RICHACL_XATTR "system.richacl" + +struct richace_xattr { + __be16 e_type; + __be16 e_flags; + __be32 e_mask; + __be32 e_id; + char e_who[0]; +}; + +struct richacl_xattr { + unsigned char a_version; + unsigned char a_flags; + __be16 a_count; + __be32 a_owner_mask; + __be32 a_group_mask; + __be32 a_other_mask; +}; + +#define ACL4_XATTR_VERSION 0 +#define ACL4_XATTR_MAX_COUNT 1024 + +extern struct richacl *richacl_from_xattr(const void *, size_t); +extern size_t richacl_xattr_size(const struct richacl *acl); +extern void richacl_to_xattr(const struct richacl *, void *); + +#endif /* __RICHACL_XATTR_H */ -- 1.6.5.2.74.g610f9