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Smack: Base support for overlayfs

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Supply the Smack module hooks in support of overlayfs.
Ensure that the Smack label of new files gets the correct
value when a directory is transmuting. Original implementation
by Romanini Daniele, with a few tweaks added.

Signed-off-by: Romanini Daniele <daniele.romanini@aalto.fi>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
This commit is contained in:
Casey Schaufler 2017-09-28 14:54:50 -07:00 committed by James Morris
parent e28aa8aeab
commit d6d80cb57b
1 changed files with 79 additions and 0 deletions
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79
security/smack/smack_lsm.c
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@ -4605,6 +4605,82 @@ static int smack_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
return 0;
}
static int smack_inode_copy_up(struct dentry *dentry, struct cred **new)
{
struct task_smack *tsp;
struct smack_known *skp;
struct inode_smack *isp;
struct cred *new_creds = *new;
if (new_creds == NULL) {
new_creds = prepare_creds();
if (new_creds == NULL)
return -ENOMEM;
}
tsp = new_creds->security;
/*
* Get label from overlay inode and set it in create_sid
*/
isp = d_inode(dentry->d_parent)->i_security;
skp = isp->smk_inode;
tsp->smk_task = skp;
*new = new_creds;
return 0;
}
static int smack_inode_copy_up_xattr(const char *name)
{
/*
* Return 1 if this is the smack access Smack attribute.
*/
if (strcmp(name, XATTR_NAME_SMACK) == 0)
return 1;
return -EOPNOTSUPP;
}
static int smack_dentry_create_files_as(struct dentry *dentry, int mode,
struct qstr *name,
const struct cred *old,
struct cred *new)
{
struct task_smack *otsp = old->security;
struct task_smack *ntsp = new->security;
struct inode_smack *isp;
int may;
/*
* Use the process credential unless all of
* the transmuting criteria are met
*/
ntsp->smk_task = otsp->smk_task;
/*
* the attribute of the containing directory
*/
isp = d_inode(dentry->d_parent)->i_security;
if (isp->smk_flags & SMK_INODE_TRANSMUTE) {
rcu_read_lock();
may = smk_access_entry(otsp->smk_task->smk_known,
isp->smk_inode->smk_known,
&otsp->smk_task->smk_rules);
rcu_read_unlock();
/*
* If the directory is transmuting and the rule
* providing access is transmuting use the containing
* directory label instead of the process label.
*/
if (may > 0 && (may & MAY_TRANSMUTE))
ntsp->smk_task = isp->smk_inode;
}
return 0;
}
static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(ptrace_access_check, smack_ptrace_access_check),
LSM_HOOK_INIT(ptrace_traceme, smack_ptrace_traceme),
@ -4740,6 +4816,9 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(inode_notifysecctx, smack_inode_notifysecctx),
LSM_HOOK_INIT(inode_setsecctx, smack_inode_setsecctx),
LSM_HOOK_INIT(inode_getsecctx, smack_inode_getsecctx),
LSM_HOOK_INIT(inode_copy_up, smack_inode_copy_up),
LSM_HOOK_INIT(inode_copy_up_xattr, smack_inode_copy_up_xattr),
LSM_HOOK_INIT(dentry_create_files_as, smack_dentry_create_files_as),
};