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Message-Id: <1265002505-8387-4-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
Date: Mon, 1 Feb 2010 11:04:45 +0530
From: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To: sfrench@...ibm.com, ffilz@...ibm.com, agruen@...e.de,
adilger@....com, sandeen@...hat.com, tytso@....edu,
staubach@...hat.com, bfields@...i.umich.edu, jlayton@...hat.com
Cc: aneesh.kumar@...ux.vnet.ibm.com, linux-fsdevel@...r.kernel.org,
nfsv4@...ux-nfs.org, linux-ext4@...r.kernel.org
Subject: [PATCH 03/23] vfs: rich ACL in-memory representation and manipulation
From: Andreas Gruenbacher <agruen@...e.de>
* 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 <agruen@...e.de>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
---
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 64d44ef..adbda7c 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 <a.gruenbacher@...puter.org>
+ *
+ * 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 <linux/sched.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/richacl.h>
+
+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 <a.gruenbacher@...puter.org>
+ *
+ * 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 <linux/module.h>
+#include <linux/fs.h>
+#include <linux/richacl.h>
+
+/**
+ * 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 <a.gruenbacher@...puter.org>
+ *
+ * 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 <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/richacl_xattr.h>
+
+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 <linux/slab.h>
+
+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 <linux/richacl.h>
+
+#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 */
--
1.7.0.rc0.48.gdace5
--
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