100 lines
1.8 KiB
Plaintext
100 lines
1.8 KiB
Plaintext
.TH CHDEV 1
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.SH NAME
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chdev \- change kernel driver access
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.SH SYNOPSIS
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.B chdev
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[ -nr ] \f2devmask\fP...
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.SH DESCRIPTION
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.I Chdev
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modifies access to kernel drivers for the current
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process and processes within the same name group
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(see
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.IR fork (2)).
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Access is defined as the ability for a process
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to walk files and directories served by the driver
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through its location within '#'. Existing binds
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of drivers are left unaffected.
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.PP
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Access may only be removed; after a specific
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driver is ejected no further operations can
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permit access again. Access is inherited by
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all children of the name group, regardless if the
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child has elected to receive a clean namespace.
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.PP
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.IR Devmask
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is a string of driver characters. The default
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behavior is to block access to all but the listed
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drivers. Flags provide a way to modify this behavior:
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.TP
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.B -r
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Retain access to all but the specified drivers.
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.TP
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.B -n
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Remove access to all drivers.
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.I Devmask
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is ignored.
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.PP
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Access to some drivers is tied to other
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related process capabilities:
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.TP
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\f2mnt\fP(3)
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.IP
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Ability to perform the
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.IR mount (2)
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system call, and
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to post new services to
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.IR shr (3).
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.TP
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\f2pipe\fP(3)
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.IP
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Ability to perform the
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.IR pipe (2)
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system call.
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.SH EXAMPLES
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Permit access to only
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.IR draw (3),
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.IR rtc (3),
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.IR fs (3),
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and
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.IR srv (3):
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.IP
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.EX
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chdev irks
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.EE
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.PP
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Remove access to
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.IR cons (3),
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.IR rtc (3),
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.IR audio (3),
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and
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.IR proc (3):
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.IP
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.EX
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chdev -r crAp
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.EE
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.PP
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Create a
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.IR pipe (3)
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then remove the ability to create more:
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.IP
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.EX
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bind '#|' /n/pipe
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chdev -r '|'
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.EE
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.SH DIAGNOSTICS
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.I Chdev
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is implemented through writes to
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.BR /dev/drivers ,
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served by
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.IR cons (3).
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.SH SOURCE
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.B /rc/bin/chdev
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.SH "SEE ALSO"
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.B /dev/drivers
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for a list of current drivers.
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.PP
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.IR intro (3),
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.IR cons (3)
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.SH HISTORY
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Chdev first appeared in 9front (May, 2022).
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