---
name: "newaid"
section: "1"
platform: "linux"
package: "sfs-common"
version: "1:0.8-0+pre20060720.1-1"
release: "Debian 4.0 (Etch)"
platforms: ["linux"]
url: "https://new.carta.tech/newaid"
---

# newaid(1)

Run processes with different sfsagents

## NAME

newaid - Run processes with different sfsagents

## SYNOPSIS

newaid \[-l\] \[-{u\|U} *uid*\] \[-G \| -g *gid*\] \[-C *dir*\] \[*program* *arg* ...\]

## DESCRIPTION

The **newaid** command allows root-owned processes to access SFS file systems using the **sfsagent** of a non-root user. Additionally, if a system is configured to allow this, **newaid** permits non-root users to run multiple **sfsagent** processes, so that different processes owned by that user access the SFS file system with different agents.  (When used in The latter mode, **newaid** is similar in function to the AFS program **pagsh**.)

SFS maps file system requests to particular **sfsagent** processes using the notion of agent ID, or **aid**.  Every process has a 64-bit aid associated with it.  Ordinarily, a process's aid is simply its 32-bit user ID.  Thus, when a user runs **sfsagent**, both the agent and all of the users' processes have the same aid.

To allow different processes owned by the same user to have different agents, a system administrator can reserve a range of group IDs for the purpose of flagging different aids. See the ResvGids directive described in the *sfs\_config* man page for a description of how to do this. (Note that after changing **ResvGids**, you must kill and restart **sfscd** for things to work properly.)  If the range of reserved group IDs is *min*...*max*, and the *first* element of a process's grouplist, *g0*, is at least *min* and not more than *max*, then a process's aid is computed as ((*g0* - *min* + 1) \<\< 32) \| *uid*).  The **newaid** command therefore lets people insert any of the reserved group IDs at the start of a process's group list.

For root-owned processes, it is also possible for processes to be associated with a non-root agent.  In this case, the reserved *sfs-group* (as a marker) and target user's uid are actually placed in the process's grouplist, as well as any reserved group ID to select amongst multiple agents of the same user.

After making appropriate changes to its user ID and/or grouplists, **newaid** executes the *program* specified on the command line.  If no *program* is specified, the program specified by the environment variable **SHELL** is used by default.

## OPTIONS

- \-l

  Run the command as a login shell.  This argument simply prepends a **-** character to **argv\[0\]** when executing *program*. Command shells interpret this to mean that they are being being run as login shells, and usually exhibit slightly different behavior.  (For example **csh** will execute the commands in a user's *.login* file.)

- \-u *uid*

  For root-owned process, specifies that the *program* should be run as root, but should be associated with the non-root agent of user *uid*.

- \-U *uid*

  When **newaid** is invoked by a root-owned processes, this option sets the real uid to *uid* to run *program*, instead of running it with uid 0.  This is in itself is not sufficient to \`\`drop privileges.''  In particular, **newaid** still does not make any changes to the process gid or grouplist, beyond manipulating aid-specific groups.  Since many root-owned processes also have privileged groups in their grouplist, it is in general **insecure** to use **-U** unless you set both the gid and the whole grouplist to something sensible (i.e., appropriately unprivileged) before invoking **newaid**.

  This option is mostly of use for **login**-like programs that wish to create a session with a new aid, and do not wish to make the **setuid** system call themselves.  As an example, the **rexd** daemon has the server's private key, yet must spawn the **proxy** program as an unprivileged user.  If it dropped privileges before executing **proxy**, unprivileged users could send it signals, risking core dumps.  Moreover, attackers might be able to exploit weaknesses in the operating system's **ptrace** system call or */proc* file system to learn the private key. **rexd** therefore runs **proxy** through **newaid**, giving it the **-U** option.

- \-g *gid*

  - \-G

  By default **newaid** simply picks the first aid under which no agent is yet running.  The **-g** option explicitly specifies that *gid* should be added to the start of the process's group list (and any previous reserved gid should be removed).  **-G** says to remove any reserved gid, so that the aid of the resulting process will just be the user's uid.

- \-C *dir*

  Changes directory to *dir* before running *program*.

## SEE ALSO

[*dirsearch*(1)](/dirsearch/1.md), [*rex*(1)](/rex/1.md), [*sfsagent*(1)](/sfsagent/1.md), [*sfskey*(1)](/sfskey/1.md), [*ssu*(1)](/ssu/1.md), *sfs\_config*(5), [*sfs\_hosts*(5)](/sfs_hosts/5.md), [*sfs\_srp\_params*(5)](/sfs_srp_params/5.md), [*sfs\_users*(5)](/sfs_users/5.md), [*sfsauthd\_config*(5)](/sfsauthd_config/5.md), [*sfscd\_config*(5)](/sfscd_config/5.md), *sfsrosd\_config*(5), [*sfsrwsd\_config*(5)](/sfsrwsd_config/5.md), [*sfssd\_config*(5)](/sfssd_config/5.md), [*sfs\_environ*(7)](/sfs_environ/7.md), [*funmount*(8)](/funmount/8.md), *nfsmounter*(8), [*sfsauthd*(8)](/sfsauthd/8.md), [*sfscd*(8)](/sfscd/8.md), *sfsrosd*(8), *sfsrwcd*(8), [*sfsrwsd*(8)](/sfsrwsd/8.md), [*sfssd*(8)](/sfssd/8.md), [*vidb*(8)](/vidb/8.md)

The full documentation for **SFS** is maintained as a Texinfo manual.  If the **info** and **SFS** programs are properly installed at your site, the command **info SFS** should give you access to the complete manual.

For updates, documentation, and software distribution, please see the **SFS** website at *http://www.fs.net/*.

## AUTHOR

sfsdev@redlab.lcs.mit.edu