124 lines
4.8 KiB
Groff
124 lines
4.8 KiB
Groff
.TH MINIJAIL0 "1" "January 2012" "Chromium OS" "User Commands"
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.SH NAME
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minijail0 \- sandbox a process
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.SH SYNOPSIS
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.B minijail0
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[\fIOPTION\fR]... <\fIprogram\fR> [\fIargs\fR]...
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.SH DESCRIPTION
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.PP
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Runs PROGRAM inside a sandbox.
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.TP
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\fB-a <table>\fR
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Run using the alternate syscall table named <table>. Only available on kernels
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and architectures that support the PR_ALT_SYSCALL option of prctl(2).
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.TP
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\fB-b <src>,<dest>[,<writeable>]
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Bind-mount <src> into the chroot directory at <dest>, optionally writeable.
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.TP
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\fB-c <caps>\fR
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Restrict capabilities to \fIcaps\fR. When used in conjunction with \fB-u\fR and
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\fB-g\fR, this allows a program to have access to only certain parts of root's
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default privileges while running as another user and group ID altogether. Note
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that these capabilities are not inherited by subprocesses of the process given
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capabilities unless those subprocesses have POSIX file capabilities. See
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\fBcapabilities\fR(7).
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.TP
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\fB-C <dir>\fR
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Change root (using chroot(2)) to <dir>.
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.TP
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\fB-e[file]\fR
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Enter a new network namespace, or if \fIfile\fR is specified, Enter an existing
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network namespace specified by \fIfile\fR which is typically of the form
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/proc/<pid>/ns/net.
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.TP
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\fB-f <file>\fR
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Write the pid of the jailed process to \fIfile\fR.
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.TP
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\fB-t\fR
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Mounts a tmpfs filesystem on /tmp. /tmp must exist in the chroot.
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This must be used with -C. The default filesystem has a max size of 128M
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and has standard /tmp permissions (777).
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.TP
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\fB-G\fR
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Inherit all the supplementary groups of the user specified with \fB-u\fR. It
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is an error to use this option without having specified a \fBuser name\fR to
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\fB-u\fR.
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.TP
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\fB-g <group>\fR
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Change groups to \fIgroup\fR, which may be either a group name or a numeric
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group ID.
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.TP
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\fB-h\fR
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Print a help message.
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.TP
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\fB-H\fR
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Print a help message detailing supported system call names for seccomp_filter.
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(Other direct numbers may be specified if minijail0 is not in sync with the
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host kernel or something like 32/64-bit compatibility issues exist.)
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.TP
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\fB-l\fR
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Run inside a new IPC namespace. This option makes the program's System V IPC
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namespace independent.
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.TP
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\fB-m "<uid> <loweruid> <count>[,<uid> <loweruid> <count>]"\fR
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Set the uid mapping of a user namespace (implies \fB-pU\fR). Same arguments as
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\fBnewuidmap(1)\fR. Multiple mappings should be separated by ','.
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.TP
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\fB-M "<uid> <loweruid> <count>[,<uid> <loweruid> <count>]"\fR
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Set the gid mapping of a user namespace (implies \fB-pU\fR). Same arguments as
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\fBnewgidmap(1)\fR. Multiple mappings should be separated by ','.
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.TP
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\fB-p\fR
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Run inside a new PID namespace. This option will make it impossible for the
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program to see or affect processes that are not its descendants. This implies
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\fB-v\fR and \fB-r\fR, since otherwise the process can see outside its namespace
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by inspecting /proc.
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.TP
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\fB-P <dir>\fR
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Set \fIdir\fR as the root fs using \fBpivot_root\fR. Implies \fB-v\fR, not
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compatible with \fB-C\fR.
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.TP
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\fB-r\fR
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Remount /proc readonly. This implies \fB-v\fR. Remounting /proc readonly means
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that even if the process has write access to a system config knob in /proc
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(e.g., in /sys/kernel), it cannot change the value.
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.TP
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\fB-s\fR
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Enable seccomp(2) in mode 1, which restricts the child process to a very small
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set of system calls.
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.TP
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\fB-S <arch-specific seccomp_filter policy file>\fR
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Enable seccomp(2) in mode 13 which restricts the child process to a set of
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system calls defined in the policy file. Note that system calls often change
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names based on the architecture or mode. (uname -m is your friend.)
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.TP
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\fB-u <user>\fR
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Change users to \fIuser\fR, which may be either a user name or a numeric user
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ID.
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.TP
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\fB-v\fR
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Run inside a new VFS namespace. This option makes the program's mountpoints
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independent of the rest of the system's.
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.TP
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\fB-V <file>\fR
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Enter the VFS namespace specified by \fIfile\fR.
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.SH IMPLEMENTATION
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This program is broken up into two parts: \fBminijail0\fR (the frontend) and a helper
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library called \fBlibminijailpreload\fR. Some jailings can only be achieved from
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the process to which they will actually apply - specifically capability use
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(since capabilities are not inherited to an exec'd process unless the exec'd
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process has POSIX file capabilities), seccomp (since we can't exec() once we're
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seccomp'd), and ptrace-disable (which is always cleared on exec().
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To this end, \fBlibminijailpreload\fR is forcibly loaded into all
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dynamically-linked target programs if any of these restrictions are in effect;
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we pass the specific restrictions in an environment variable which the preloaded
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library looks for. The forcibly-loaded library then applies the restrictions
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to the newly-loaded program.
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.SH AUTHOR
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Written by Elly Jones (ellyjones@chromium.org)
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.SH COPYRIGHT
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Copyright \(co 2011 The Chromium OS Authors
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License BSD-like.
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.SH "SEE ALSO"
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\fBlibminijail.h\fR \fBminijail0(5)\fR
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