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LSM: SafeSetID: refactor safesetid_security_capable()

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At the moment, safesetid_security_capable() has two nested conditional
blocks, and one big comment for all the logic. Chop it up and reduce the
amount of indentation.

Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Micah Morton <mortonm@chromium.org>
This commit is contained in:
Jann Horn 2019-04-10 09:55:41 -07:00 committed by Micah Morton
parent 1cd02a27a9
commit 8068866c4a
1 changed files with 26 additions and 15 deletions
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41
security/safesetid/lsm.c
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@ -55,21 +55,32 @@ static int safesetid_security_capable(const struct cred *cred,
int cap,
unsigned int opts)
{
if (cap == CAP_SETUID &&
setuid_policy_lookup(cred->uid, INVALID_UID) != SIDPOL_DEFAULT) {
if (!(opts & CAP_OPT_INSETID)) {
/*
* Deny if we're not in a set*uid() syscall to avoid
* giving powers gated by CAP_SETUID that are related
* to functionality other than calling set*uid() (e.g.
* allowing user to set up userns uid mappings).
*/
pr_warn("Operation requires CAP_SETUID, which is not available to UID %u for operations besides approved set*uid transitions\n",
__kuid_val(cred->uid));
return -1;
}
}
return 0;
/* We're only interested in CAP_SETUID. */
if (cap != CAP_SETUID)
return 0;
/*
* If CAP_SETUID is currently used for a set*uid() syscall, we want to
* let it go through here; the real security check happens later, in the
* task_fix_setuid hook.
*/
if ((opts & CAP_OPT_INSETID) != 0)
return 0;
/*
* If no policy applies to this task, allow the use of CAP_SETUID for
* other purposes.
*/
if (setuid_policy_lookup(cred->uid, INVALID_UID) == SIDPOL_DEFAULT)
return 0;
/*
* Reject use of CAP_SETUID for functionality other than calling
* set*uid() (e.g. setting up userns uid mappings).
*/
pr_warn("Operation requires CAP_SETUID, which is not available to UID %u for operations besides approved set*uid transitions\n",
__kuid_val(cred->uid));
return -1;
}
/*