.\" Automatically generated by Pod::Man 2.25 (Pod::Simple 3.16) .\" .\" Standard preamble: .\" ======================================================================== .de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. .de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. .de Ve \" End verbatim text .ft R .fi .. .\" Set up some character translations and predefined strings. \*(-- will .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left .\" double quote, and \*(R" will give a right double quote. \*(C+ will .\" give a nicer C++. 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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" pagsh, pagsh.krb \- Creates a new PAG .SH "SYNOPSIS" .IX Header "SYNOPSIS" \&\fBpagsh\fR .PP \&\fBpagsh.krb\fR .SH "DESCRIPTION" .IX Header "DESCRIPTION" The \fBpagsh\fR command creates a new command shell (owned by the issuer of the command) and associates a new \fIprocess authentication group\fR (\s-1PAG\s0) with the shell and the user. A \s-1PAG\s0 is a number guaranteed to identify the issuer of commands in the new shell uniquely to the local Cache Manager. The \s-1PAG\s0 is used, instead of the issuer's \s-1UNIX\s0 \s-1UID\s0, to identify the issuer in the credential structure that the Cache Manager creates to track each user. .PP Any tokens acquired subsequently (presumably for other cells) become associated with the \s-1PAG\s0, rather than with the user's \s-1UNIX\s0 \s-1UID\s0. This method for distinguishing users has two advantages: .IP "\(bu" 2 It means that processes spawned by the user inherit the \s-1PAG\s0 and so share the token; thus they gain access to \s-1AFS\s0 as the authenticated user. In many environments, for example, printer and other daemons run under identities (such as the local superuser \f(CW\*(C`root\*(C'\fR) that the \s-1AFS\s0 server processes recognize only as \f(CW\*(C`anonymous\*(C'\fR. Unless PAGs are used, such daemons cannot access files in directories whose access control lists (ACLs) do not extend permissions to the system:anyuser group. .IP "\(bu" 2 It closes a potential security loophole: \s-1UNIX\s0 allows anyone already logged in as the local superuser \f(CW\*(C`root\*(C'\fR on a machine to assume any other identity by issuing the \s-1UNIX\s0 \fBsu\fR command. If the credential structure is identified by a \s-1UNIX\s0 \s-1UID\s0 rather than a \s-1PAG\s0, then the local superuser \&\f(CW\*(C`root\*(C'\fR can assume a \s-1UNIX\s0 \s-1UID\s0 and use any tokens associated with that \&\s-1UID\s0. Use of a \s-1PAG\s0 as an identifier eliminates that possibility. .PP The (mostly obsolete) \fBpagsh.krb\fR command is the same as \fBpagsh\fR except that it also sets the \s-1KRBTKFILE\s0 environment variable, which controls the default Kerberos v4 ticket cache, to \fI/tmp/tktp\fIX\fI\fR where \fIX\fR is the number of the user's \s-1PAG\s0. This is only useful for \s-1AFS\s0 cells still using Kerberos v4 outside of \s-1AFS\s0 and has no effect for cells using Kerberos v5 and \fBaklog\fR or \fBklog.krb5\fR. .SH "CAUTIONS" .IX Header "CAUTIONS" Each \s-1PAG\s0 created uses two of the memory slots that the kernel uses to record the \s-1UNIX\s0 groups associated with a user. If none of these slots are available, the \fBpagsh\fR command fails. This is not a problem with most operating systems, which make at least 16 slots available per user. .PP In cells that do not use an AFS-modified login utility, use this command to obtain a \s-1PAG\s0 before issuing the \fBklog\fR command (or include the \&\fB\-setpag\fR argument to the \fBklog\fR command). If a \s-1PAG\s0 is not acquired, the Cache Manager stores the token in a credential structure identified by local \s-1UID\s0 rather than \s-1PAG\s0. This creates the potential security exposure described in \s-1DESCRIPTION\s0. .PP If users of \s-1NFS\s0 client machines for which \s-1AFS\s0 is supported are to issue this command as part of authenticating with \s-1AFS\s0, do not use the \fBfs exportafs\fR command's \fB\-uidcheck on\fR argument to enable \s-1UID\s0 checking on \&\s-1NFS/AFS\s0 Translator machines. Enabling \s-1UID\s0 checking prevents this command from succeeding. See \fIklog\fR\|(1). .PP If \s-1UID\s0 checking is not enabled on Translator machines, then by default it is possible to issue this command on a properly configured \s-1NFS\s0 client machine that is accessing \s-1AFS\s0 via the \s-1NFS/AFS\s0 Translator, assuming that the \s-1NFS\s0 client machine is a supported system type. The \fBpagsh\fR binary accessed by the \s-1NFS\s0 client must be owned by, and grant setuid privilege to, the local superuser \f(CW\*(C`root\*(C'\fR. The complete set of mode bits must be \&\f(CW\*(C`\-rwsr\-xr\-x\*(C'\fR. This is not a requirement when the command is issued on \s-1AFS\s0 client machines. .PP However, if the translator machine's administrator has enabled \s-1UID\s0 checking by including the \fB\-uidcheck on\fR argument to the \fBfs exportafs\fR command, the command fails with an error message similar to the following: .PP .Vb 2 \& Warning: Remote setpag to has failed (err=8). . . \& setpag: Exec format error .Ve .SH "EXAMPLES" .IX Header "EXAMPLES" In the following example, the issuer invokes the C shell instead of the default Bourne shell: .PP .Vb 1 \& # pagsh \-c /bin/csh .Ve .SH "PRIVILEGE REQUIRED" .IX Header "PRIVILEGE REQUIRED" None .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fIaklog\fR\|(1), \&\fIfs_exportafs\fR\|(1), \&\fIklog\fR\|(1), \&\fItokens\fR\|(1) .SH "COPYRIGHT" .IX Header "COPYRIGHT" \&\s-1IBM\s0 Corporation 2000. All Rights Reserved. .PP This documentation is covered by the \s-1IBM\s0 Public License Version 1.0. It was converted from \s-1HTML\s0 to \s-1POD\s0 by software written by Chas Williams and Russ Allbery, based on work by Alf Wachsmann and Elizabeth Cassell.