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.\" generated with Ronn-NG/v0.9.1
.\" http://github.com/apjanke/ronn-ng/tree/0.9.1
.TH "PAM_CAP" "8" "April 2024" ""
.SH "NAME"
\fBpam_cap\fR \- Capabilities PAM module
.SH "SYNOPSIS"
[service\-name] \fBauth\fR control\-flag \fBpam_cap\fR [options]
.SH "DESCRIPTION"
The \fBpam_so\fR module can be used to specify \fIInheritable\fR capabilities to process trees rooted in the PAM application\. The module also supports blocking \fIBounding\fR vector capabilities and adding \fIAmbient\fR vector capabilities\.
.P
For general PAM apps to work correctly, the application must be run with at least \fBCAP_SETPCAP\fR raised in its \fIPermitted\fR capability flag\. Many PAM applications run as \fIroot\fR, which has all of the bits in the \fIBounding\fR set raised, so this requirement is typically met\. To grant an \fIAmbient\fR vector capability, the corresponding Permitted bit must be available to the application too\.
.P
The \fBpam_so\fR module is a Linux\-PAM \fIauth\fR module\. It provides functionality to back \fBpam_sm_authenticate()\fR and \fBpam_sm_setcred()\fR\. It is the latter that actually modifies the inheritable 3\-tuple of capability vectors: the configured \fIIAB\fR\. In a typical application configuration you might have a line like this:
.IP "" 4
.nf
auth optional pam_cap\.so
.fi
.IP "" 0
.P
The module arguments are:
.IP "\[ci]" 4
\fBdebug\fR: While supported, this is a no\-op at present\.
.IP "\[ci]" 4
\fBconfig=\fR\fI/path/to/file\fR: Override the default config for the module\. The unspecified default value for this file is \fB/etc/security/capability\.conf\fR\. Note, \fBconfig=/dev/null\fR is a valid value\. See \fBdefault=\fR below for situations in which this might be appropriate\.
.IP "\[ci]" 4
\fBkeepcaps\fR: This is as much as the \fBpam_cap\.so\fR module can do to help an application support use of the \fIAmbient\fR capability vector\. The application support for the \fIAmbient\fR set is poor at the present time\.
.IP "\[ci]" 4
\fBautoauth\fR: This argument causes the \fBpam_cap\.so\fR module to return \fBPAM_SUCCESS\fR if the \fBPAM_USER\fR being authenticated exists\. The absence of this argument will cause \fBpam_cap\.so\fR to only return \fBPAM_SUCCESS\fR if the \fBPAM_USER\fR is covered by a specific rule in the prevailing config file\.
.IP "\[ci]" 4
\fBdefault=\fR\fIIAB\fR: This argument is ignored if the prevailing configuration file contains a "\fB*\fR" rule\. If there is no such rule, the \fIIAB\fR 3\-tuple is inserted at the end of the config file and applies to all \fBPAM_USER\fRs not covered by an earlier rule\. Note, if you want all \fBPAM_USER\fRs to be covered by this default rule, you can supply the module argument \fBconfig=/dev/null\fR\.
.IP "\[ci]" 4
\fBdefer\fR: This argument arranges for the \fIIAB\fR capabilities granted to a user to be added sufficiently late in the Linux\-PAM authentication stack that they stick\. That is, \fIafter\fR the application does its \fBsetuid(UID)\fR call\. As such, in conjunction with the \fBkeepcaps\fR module argument, such compliant applications can support granting \fIAmbient\fR vector capabilities with \fBpam_cap\.so\fR\.
.IP "" 0
.SH "SEE ALSO"
pam\.conf(5), capability\.conf(5), pam(8)
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