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apparmor: rework file permission to cache file access in file->ctx

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This is a temporary step, towards using the file->ctx for delegation,
and also helps speed up file queries, until the permission lookup
cache is introduced.

Signed-off-by: John Johansen <john.johansen@canonical.com>
This commit is contained in:
John Johansen 2017-06-09 16:19:02 -07:00
parent 8014370f12
commit 496c931966
1 changed files with 76 additions and 6 deletions
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82
security/apparmor/file.c
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@ -492,6 +492,80 @@ int aa_path_link(struct aa_label *label, struct dentry *old_dentry,
return error;
}
static void update_file_ctx(struct aa_file_ctx *fctx, struct aa_label *label,
u32 request)
{
struct aa_label *l, *old;
/* update caching of label on file_ctx */
spin_lock(&fctx->lock);
old = rcu_dereference_protected(fctx->label,
spin_is_locked(&fctx->lock));
l = aa_label_merge(old, label, GFP_ATOMIC);
if (l) {
if (l != old) {
rcu_assign_pointer(fctx->label, l);
aa_put_label(old);
} else
aa_put_label(l);
fctx->allow |= request;
}
spin_unlock(&fctx->lock);
}
static int __file_path_perm(const char *op, struct aa_label *label,
struct aa_label *flabel, struct file *file,
u32 request, u32 denied)
{
struct aa_profile *profile;
struct aa_perms perms = {};
struct path_cond cond = {
.uid = file_inode(file)->i_uid,
.mode = file_inode(file)->i_mode
};
char *buffer;
int flags, error;
/* revalidation due to label out of date. No revocation at this time */
if (!denied && aa_label_is_subset(flabel, label))
/* TODO: check for revocation on stale profiles */
return 0;
flags = PATH_DELEGATE_DELETED | (S_ISDIR(cond.mode) ? PATH_IS_DIR : 0);
get_buffers(buffer);
/* check every profile in task label not in current cache */
error = fn_for_each_not_in_set(flabel, label, profile,
profile_path_perm(op, profile, &file->f_path, buffer,
request, &cond, flags, &perms));
if (denied && !error) {
/*
* check every profile in file label that was not tested
* in the initial check above.
*
* TODO: cache full perms so this only happens because of
* conditionals
* TODO: don't audit here
*/
if (label == flabel)
error = fn_for_each(label, profile,
profile_path_perm(op, profile, &file->f_path,
buffer, request, &cond, flags,
&perms));
else
error = fn_for_each_not_in_set(label, flabel, profile,
profile_path_perm(op, profile, &file->f_path,
buffer, request, &cond, flags,
&perms));
}
if (!error)
update_file_ctx(file_ctx(file), label, request);
put_buffers(buffer);
return error;
}
/**
* aa_file_perm - do permission revalidation check & audit for @file
* @op: operation being checked
@ -504,10 +578,6 @@ int aa_path_link(struct aa_label *label, struct dentry *old_dentry,
int aa_file_perm(const char *op, struct aa_label *label, struct file *file,
u32 request)
{
struct path_cond cond = {
.uid = file_inode(file)->i_uid,
.mode = file_inode(file)->i_mode
};
struct aa_file_ctx *fctx;
struct aa_label *flabel;
u32 denied;
@ -537,8 +607,8 @@ int aa_file_perm(const char *op, struct aa_label *label, struct file *file,
/* TODO: label cross check */
if (file->f_path.mnt && path_mediated_fs(file->f_path.dentry))
error = aa_path_perm(op, label, &file->f_path,
PATH_DELEGATE_DELETED, request, &cond);
error = __file_path_perm(op, label, flabel, file, request,
denied);
done:
rcu_read_unlock();