diff options
Diffstat (limited to 'doc/safe.n')
| -rw-r--r-- | doc/safe.n | 329 |
1 files changed, 77 insertions, 252 deletions
@@ -3,33 +3,30 @@ '\" '\" See the file "license.terms" for information on usage and redistribution '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. -'\" +'\" .TH "Safe Tcl" n 8.0 Tcl "Tcl Built-In Commands" .so man.macros .BS '\" Note: do not modify the .SH NAME line immediately below! .SH NAME -safe \- Creating and manipulating safe interpreters +Safe\ Base \- A mechanism for creating and manipulating safe interpreters .SH SYNOPSIS -\fB::safe::interpCreate\fR ?\fIchild\fR? ?\fIoptions...\fR? -.sp -\fB::safe::interpInit\fR \fIchild\fR ?\fIoptions...\fR? +\fB::safe::interpCreate\fR ?\fIslave\fR? ?\fIoptions...\fR? .sp -\fB::safe::interpConfigure\fR \fIchild\fR ?\fIoptions...\fR? +\fB::safe::interpInit\fR \fIslave\fR ?\fIoptions...\fR? .sp -\fB::safe::interpDelete\fR \fIchild\fR +\fB::safe::interpConfigure\fR \fIslave\fR ?\fIoptions...\fR? .sp -\fB::safe::interpAddToAccessPath\fR \fIchild\fR \fIdirectory\fR +\fB::safe::interpDelete\fR \fIslave\fR .sp -\fB::safe::interpFindInAccessPath\fR \fIchild\fR \fIdirectory\fR +\fB::safe::interpAddToAccessPath\fR \fIslave\fR \fIdirectory\fR .sp -\fB::safe::setSyncMode\fR ?\fInewValue\fR? +\fB::safe::interpFindInAccessPath\fR \fIslave\fR \fIdirectory\fR .sp \fB::safe::setLogCmd\fR ?\fIcmd arg...\fR? .SS OPTIONS .PP ?\fB\-accessPath\fR \fIpathList\fR? -?\fB\-autoPath\fR \fIpathList\fR? ?\fB\-statics\fR \fIboolean\fR? ?\fB\-noStatics\fR? ?\fB\-nested\fR \fIboolean\fR? ?\fB\-nestedLoadOk\fR? ?\fB\-deleteHook\fR \fIscript\fR? @@ -39,15 +36,15 @@ Safe Tcl is a mechanism for executing untrusted Tcl scripts safely and for providing mediated access by such scripts to potentially dangerous functionality. .PP -Safe Tcl ensures that untrusted Tcl scripts cannot harm the +The Safe Base ensures that untrusted Tcl scripts cannot harm the hosting application. -It prevents integrity and privacy attacks. Untrusted Tcl +The Safe Base prevents integrity and privacy attacks. Untrusted Tcl scripts are prevented from corrupting the state of the hosting application or computer. Untrusted scripts are also prevented from disclosing information stored on the hosting computer or in the hosting application to any party. .PP -Safe Tcl allows a parent interpreter to create safe, restricted +The Safe Base allows a master interpreter to create safe, restricted interpreters that contain a set of predefined aliases for the \fBsource\fR, \fBload\fR, \fBfile\fR, \fBencoding\fR, and \fBexit\fR commands and are able to use the auto-loading and package mechanisms. @@ -56,47 +53,39 @@ No knowledge of the file system structure is leaked to the safe interpreter, because it has access only to a virtualized path containing tokens. When the safe interpreter requests to source a file, it uses the token in the virtual path as part of the file name to source; the -parent interpreter transparently -translates the token into a real directory name and executes the +master interpreter transparently +translates the token into a real directory name and executes the requested operation (see the section \fBSECURITY\fR below for details). Different levels of security can be selected by using the optional flags of the commands described below. .PP -All commands provided in the parent interpreter by Safe Tcl reside in +All commands provided in the master interpreter by the Safe Base reside in the \fBsafe\fR namespace. .SH COMMANDS -The following commands are provided in the parent interpreter: +The following commands are provided in the master interpreter: .TP -\fB::safe::interpCreate\fR ?\fIchild\fR? ?\fIoptions...\fR? +\fB::safe::interpCreate\fR ?\fIslave\fR? ?\fIoptions...\fR? Creates a safe interpreter, installs the aliases described in the section \fBALIASES\fR and initializes the auto-loading and package mechanism as specified by the supplied \fIoptions\fR. See the \fBOPTIONS\fR section below for a description of the optional arguments. -If the \fIchild\fR argument is omitted, a name will be generated. +If the \fIslave\fR argument is omitted, a name will be generated. \fB::safe::interpCreate\fR always returns the interpreter name. -.sp -The interpreter name \fIchild\fR may include namespace separators, -but may not have leading or trailing namespace separators, or excess -colon characters in namespace separators. The interpreter name is -qualified relative to the global namespace ::, not the namespace in which -the \fB::safe::interpCreate\fR command is evaluated. .TP -\fB::safe::interpInit\fR \fIchild\fR ?\fIoptions...\fR? +\fB::safe::interpInit\fR \fIslave\fR ?\fIoptions...\fR? This command is similar to \fBinterpCreate\fR except it that does not -create the safe interpreter. \fIchild\fR must have been created by some -other means, like \fBinterp create\fR \fB\-safe\fR. The interpreter -name \fIchild\fR may include namespace separators, subject to the same -restrictions as for \fBinterpCreate\fR. +create the safe interpreter. \fIslave\fR must have been created by some +other means, like \fBinterp create \-safe\fR. .TP -\fB::safe::interpConfigure\fR \fIchild\fR ?\fIoptions...\fR? +\fB::safe::interpConfigure\fR \fIslave\fR ?\fIoptions...\fR? If no \fIoptions\fR are given, returns the settings for all options for the named safe interpreter as a list of options and their current values -for that \fIchild\fR. +for that \fIslave\fR. If a single additional argument is provided, it will return a list of 2 elements \fIname\fR and \fIvalue\fR where \fIname\fR is the full name of that option and \fIvalue\fR the current value -for that option and the \fIchild\fR. +for that option and the \fIslave\fR. If more than two additional arguments are provided, it will reconfigure the safe interpreter and change each and only the provided options. See the section on \fBOPTIONS\fR below for options description. @@ -116,14 +105,14 @@ safe::interpConfigure $i0 \-delete {foo bar} \-statics 0 .CE .RE .TP -\fB::safe::interpDelete\fR \fIchild\fR -Deletes the safe interpreter and cleans up the corresponding -parent interpreter data structures. +\fB::safe::interpDelete\fR \fIslave\fR +Deletes the safe interpreter and cleans up the corresponding +master interpreter data structures. If a \fIdeleteHook\fR script was specified for this interpreter it is evaluated before the interpreter is deleted, with the name of the interpreter as an additional argument. .TP -\fB::safe::interpFindInAccessPath\fR \fIchild\fR \fIdirectory\fR +\fB::safe::interpFindInAccessPath\fR \fIslave\fR \fIdirectory\fR This command finds and returns the token for the real directory \fIdirectory\fR in the safe interpreter's current virtual access path. It generates an error if the directory is not found. @@ -131,14 +120,14 @@ Example of use: .RS .PP .CS -$child eval [list set tk_library \e +$slave eval [list set tk_library \e [::safe::interpFindInAccessPath $name $tk_library]] .CE .RE .TP -\fB::safe::interpAddToAccessPath\fR \fIchild\fR \fIdirectory\fR +\fB::safe::interpAddToAccessPath\fR \fIslave\fR \fIdirectory\fR This command adds \fIdirectory\fR to the virtual path maintained for the -safe interpreter in the parent, and returns the token that can be used in +safe interpreter in the master, and returns the token that can be used in the safe interpreter to obtain access to files in that directory. If the directory is already in the virtual path, it only returns the token without adding the directory to the virtual path again. @@ -146,20 +135,11 @@ Example of use: .RS .PP .CS -$child eval [list set tk_library \e +$slave eval [list set tk_library \e [::safe::interpAddToAccessPath $name $tk_library]] .CE .RE .TP -\fB::safe::setSyncMode\fR ?\fInewValue\fR? -This command is used to get or set the "Sync Mode" of the Safe Base. -When an argument is supplied, the command returns an error if the argument -is not a boolean value, or if any Safe Base interpreters exist. Typically -the value will be set as part of initialization - boolean true for -"Sync Mode" on (the default), false for "Sync Mode" off. With "Sync Mode" -on, the Safe Base keeps each child interpreter's ::auto_path synchronized -with its access path. See the section \fBSYNC MODE\fR below for details. -.TP \fB::safe::setLogCmd\fR ?\fIcmd arg...\fR? This command installs a script that will be called when interesting life cycle events occur for a safe interpreter. @@ -188,40 +168,33 @@ Note that the safe interpreter only received an error message saying that the file was not found: .PP .CS -NOTICE for child interp10 : Created -NOTICE for child interp10 : Setting accessPath=(/foo/bar) staticsok=1 nestedok=0 deletehook=() -NOTICE for child interp10 : auto_path in interp10 has been set to {$p(:0:)} -ERROR for child interp10 : /foo/bar/init.tcl: no such file or directory +NOTICE for slave interp10 : Created +NOTICE for slave interp10 : Setting accessPath=(/foo/bar) staticsok=1 nestedok=0 deletehook=() +NOTICE for slave interp10 : auto_path in interp10 has been set to {$p(:0:)} +ERROR for slave interp10 : /foo/bar/init.tcl: no such file or directory .CE .RE .SS OPTIONS -The following options are common to -\fB::safe::interpCreate\fR, \fB::safe::interpInit\fR, +The following options are common to +\fB::safe::interpCreate\fR, \fB::safe::interpInit\fR, and \fB::safe::interpConfigure\fR. -Any option name can be abbreviated to its minimal +Any option name can be abbreviated to its minimal non-ambiguous name. Option names are not case sensitive. -.TP +.TP \fB\-accessPath\fR \fIdirectoryList\fR This option sets the list of directories from which the safe interpreter can \fBsource\fR and \fBload\fR files. If this option is not specified, or if it is given as the empty list, the safe interpreter will use the same directories as its -parent for auto-loading. -See the section \fBSECURITY\fR below for more detail about virtual paths, +master for auto-loading. +See the section \fBSECURITY\fR below for more detail about virtual paths, tokens and access control. .TP -\fB\-autoPath\fR \fIdirectoryList\fR -This option sets the list of directories in the safe interpreter's -::auto_path. The option is undefined if the Safe Base has "Sync Mode" on -- in that case the safe interpreter's ::auto_path is managed by the Safe -Base and is a tokenized form of its access path. -See the section \fBSYNC MODE\fR below for details. -.TP \fB\-statics\fR \fIboolean\fR This option specifies if the safe interpreter will be allowed to load statically linked packages (like \fBload {} Tk\fR). -The default value is \fBtrue\fR : +The default value is \fBtrue\fR : safe interpreters are allowed to load statically linked packages. .TP \fB\-noStatics\fR @@ -232,7 +205,7 @@ to load statically linked packages. \fB\-nested\fR \fIboolean\fR This option specifies if the safe interpreter will be allowed to load packages into its own sub-interpreters. -The default value is \fBfalse\fR : +The default value is \fBfalse\fR : safe interpreters are not allowed to load packages into their own sub-interpreters. .TP @@ -240,10 +213,10 @@ their own sub-interpreters. This option is a convenience shortcut for \fB\-nested true\fR and thus specifies the safe interpreter will be allowed to load packages into its own sub-interpreters. -.TP +.TP \fB\-deleteHook\fR \fIscript\fR When this option is given a non-empty \fIscript\fR, it will be -evaluated in the parent with the name of +evaluated in the master with the name of the safe interpreter as an additional argument just before actually deleting the safe interpreter. Giving an empty value removes any currently installed deletion hook @@ -288,13 +261,13 @@ the system encoding, but allows all other subcommands including The calling interpreter is deleted and its computation is stopped, but the Tcl process in which this interpreter exists is not terminated. .SH SECURITY -Safe Tcl does not attempt to completely prevent annoyance and +The Safe Base does not attempt to completely prevent annoyance and denial of service attacks. These forms of attack prevent the application or user from temporarily using the computer to perform useful work, for example by consuming all available CPU time or all available screen real estate. These attacks, while aggravating, are deemed to be of lesser importance -in general than integrity and privacy attacks that Safe Tcl +in general than integrity and privacy attacks that the Safe Base is to prevent. .PP The commands available in a safe interpreter, in addition to @@ -308,22 +281,22 @@ potential for information leakage about its directory structure. To prevent this, commands that take file names as arguments in a safe interpreter use tokens instead of the real directory names. These tokens are translated to the real directory name while a request to, -e.g., source a file is mediated by the parent interpreter. -This virtual path system is maintained in the parent interpreter for each safe +e.g., source a file is mediated by the master interpreter. +This virtual path system is maintained in the master interpreter for each safe interpreter created by \fB::safe::interpCreate\fR or initialized by \fB::safe::interpInit\fR and the path maps tokens accessible in the safe interpreter into real path -names on the local file system thus preventing safe interpreters +names on the local file system thus preventing safe interpreters from gaining knowledge about the structure of the file system of the host on which the interpreter is executing. The only valid file names arguments -for the \fBsource\fR and \fBload\fR aliases provided to the child -are path in the form of -\fB[file join \fItoken filename\fB]\fR (i.e. when using the -native file path formats: \fItoken\fB/\fIfilename\fR -on Unix and \fItoken\fB\e\fIfilename\fR on Windows), -where \fItoken\fR is representing one of the directories +for the \fBsource\fR and \fBload\fR aliases provided to the slave +are path in the form of +\fB[file join \fR\fItoken filename\fR\fB]\fR (i.e. when using the +native file path formats: \fItoken\fR\fB/\fR\fIfilename\fR +on Unix and \fItoken\fR\fB\e\fIfilename\fR on Windows), +where \fItoken\fR is representing one of the directories of the \fIaccessPath\fR list and \fIfilename\fR is one file in that directory (no sub directories access are allowed). .PP @@ -347,29 +320,28 @@ or be called .PP Each element of the initial access path list will be assigned a token that will be set in -the child \fBauto_path\fR and the first element of that list will be set as -the \fBtcl_library\fR for that child. +the slave \fBauto_path\fR and the first element of that list will be set as +the \fBtcl_library\fR for that slave. .PP -If the access path argument is not given to \fB::safe::interpCreate\fR or -\fB::safe::interpInit\fR or is the empty list, -the default behavior is to let the child access the same packages -as the parent has access to (Or to be more precise: +If the access path argument is not given or is the empty list, +the default behavior is to let the slave access the same packages +as the master has access to (Or to be more precise: only packages written in Tcl (which by definition cannot be dangerous -as they run in the child interpreter) and C extensions that -provides a _SafeInit entry point). For that purpose, the parent's -\fBauto_path\fR will be used to construct the child access path. -In order that the child successfully loads the Tcl library files +as they run in the slave interpreter) and C extensions that +provides a _SafeInit entry point). For that purpose, the master's +\fBauto_path\fR will be used to construct the slave access path. +In order that the slave successfully loads the Tcl library files (which includes the auto-loading mechanism itself) the \fBtcl_library\fR will be -added or moved to the first position if necessary, in the -child access path, so the child -\fBtcl_library\fR will be the same as the parent's (its real -path will still be invisible to the child though). -In order that auto-loading works the same for the child and -the parent in this by default case, the first-level -sub directories of each directory in the parent \fBauto_path\fR will -also be added (if not already included) to the child access path. +added or moved to the first position if necessary, in the +slave access path, so the slave +\fBtcl_library\fR will be the same as the master's (its real +path will still be invisible to the slave though). +In order that auto-loading works the same for the slave and +the master in this by default case, the first-level +sub directories of each directory in the master \fBauto_path\fR will +also be added (if not already included) to the slave access path. You can always specify a more -restrictive path for which sub directories will never be searched by +restrictive path for which sub directories will never be searched by explicitly specifying your directory list with the \fB\-accessPath\fR flag instead of relying on this default mechanism. .PP @@ -377,155 +349,8 @@ When the \fIaccessPath\fR is changed after the first creation or initialization (i.e. through \fBinterpConfigure -accessPath \fR\fIlist\fR), an \fBauto_reset\fR is automatically evaluated in the safe interpreter to synchronize its \fBauto_index\fR with the new token list. -.SH TYPICAL USE -In many cases, the properties of a Safe Base interpreter can be specified -when the interpreter is created, and then left unchanged for the lifetime -of the interpreter. -.PP -If you wish to use Safe Base interpreters with "Sync Mode" off, evaluate -the command -.RS -.PP -.CS - safe::setSyncMode 0 -.CE -.RE -.PP -Use \fB::safe::interpCreate\fR or \fB::safe::interpInit\fR to create an -interpreter with the properties that you require. The simplest way is not -to specify \fB\-accessPath\fR or \fB\-autoPath\fR, which means the safe -interpreter will use the same paths as the parent interpreter. However, -if \fB\-accessPath\fR is specified, then \fB\-autoPath\fR must also be -specified, or else it will be set to {}. -.PP -The value of \fB\-autoPath\fR will be that required to access tclIndex -and pkgIndex.tcl files according to the same rules as an unsafe -interpreter (see pkg_mkIndex(n) and library(n)). -.PP -With "Sync Mode" on, the option \fB\-autoPath\fR is undefined, and -the Safe Base sets the child's ::auto_path to a tokenized form of the -access path. In addition to the directories present if "Safe Mode" is off, -the ::auto_path includes the numerous subdirectories and module paths -that belong to the access path. -.SH SYNC MODE -Before Tcl version 8.7, the Safe Base kept each safe interpreter's -::auto_path synchronized with a tokenized form of its access path. -Limitations of Tcl 8.4 and earlier made this feature necessary. This -definition of ::auto_path did not conform its specification in library(n) -and pkg_mkIndex(n), but nevertheless worked perfectly well for the discovery -and loading of packages. The introduction of Tcl modules in Tcl 8.5 added a -large number of directories to the access path, and it is inconvenient to -have these additional directories unnecessarily appended to the ::auto_path. -.PP -In order to preserve compatibility with existing code, this synchronization -of the ::auto_path and access path ("Sync Mode" on) is still the default. -However, the Safe Base offers the option of limiting the safe interpreter's -::auto_path to the much shorter list of directories that is necessary for -it to perform its function ("Sync Mode" off). Use the command -\fB::safe::setSyncMode\fR to choose the mode before creating any Safe -Base interpreters. -.PP -In either mode, the most convenient way to initialize a safe interpreter is -to call \fB::safe::interpCreate\fR or \fB::safe::interpInit\fR without the -\fB\-accessPath\fR or \fB\-autoPath\fR options (or with the \fB\-accessPath\fR -option set to the -empty list), which will give the safe interpreter the same access as the -parent interpreter to packages, modules, and autoloader files. With -"Sync Mode" off, the Safe Base will set the value of \fB\-autoPath\fR to the -parent's ::auto_path, and will set the child's ::auto_path to a tokenized form -of the parent's ::auto_path. -.PP -With "Sync Mode" off, if a value is specified for \fB\-autoPath\fR, even the empty -list, in a call to \fB::safe::interpCreate\fR, \fB::safe::interpInit\fR, or -\fB::safe::interpConfigure\fR, it will be tokenized and used as the safe -interpreter's ::auto_path. Any directories that do not also belong to the -access path cannot be tokenized and will be silently ignored. However, the -value of \fB\-autoPath\fR will remain as specified, and will be used to -re-tokenize the child's ::auto_path if \fB::safe::interpConfigure\fR is called -to change the value of \fB\-accessPath\fR. -.PP -With "Sync Mode" off, if the access path is reset to the values in the -parent interpreter by calling \fB::safe::interpConfigure\fR with arguments -\fB\-accessPath\fR {}, then the ::auto_path will also be reset unless the argument -\fB\-autoPath\fR is supplied to specify a different value. -.PP -With "Sync Mode" off, if a non-empty value of \fB\-accessPath\fR is supplied, the -safe interpreter's ::auto_path will be set to {} (by -\fB::safe::interpCreate\fR, \fB::safe::interpInit\fR) or left unchanged -(by \fB::safe::interpConfigure\fR). If the same command specifies a new -value for \fB\-autoPath\fR, it will be applied after the \fB\-accessPath\fR argument has -been processed. - -Examples of use with "Sync Mode" off: any of these commands will set the -::auto_path to a tokenized form of its value in the parent interpreter: -.RS -.PP -.CS - safe::interpCreate foo - safe::interpCreate foo -accessPath {} - safe::interpInit bar - safe::interpInit bar -accessPath {} - safe::interpConfigure foo -accessPath {} -.CE -.RE -.PP -Example of use with "Sync Mode" off: when initializing a safe interpreter -with a non-empty access path, the ::auto_path will be set to {} unless its -own value is also specified: -.RS -.PP -.CS - safe::interpCreate foo -accessPath { - /usr/local/TclHome/lib/tcl8.6 - /usr/local/TclHome/lib/tcl8.6/http1.0 - /usr/local/TclHome/lib/tcl8.6/opt0.4 - /usr/local/TclHome/lib/tcl8.6/msgs - /usr/local/TclHome/lib/tcl8.6/encoding - /usr/local/TclHome/lib - } - - # The child's ::auto_path must be given a suitable value: - - safe::interpConfigure foo -autoPath { - /usr/local/TclHome/lib/tcl8.6 - /usr/local/TclHome/lib - } - - # The two commands can be combined: - - safe::interpCreate foo -accessPath { - /usr/local/TclHome/lib/tcl8.6 - /usr/local/TclHome/lib/tcl8.6/http1.0 - /usr/local/TclHome/lib/tcl8.6/opt0.4 - /usr/local/TclHome/lib/tcl8.6/msgs - /usr/local/TclHome/lib/tcl8.6/encoding - /usr/local/TclHome/lib - } -autoPath { - /usr/local/TclHome/lib/tcl8.6 - /usr/local/TclHome/lib - } -.CE -.RE -.PP -Example of use with "Sync Mode" off: the command -\fBsafe::interpAddToAccessPath\fR does not change the safe interpreter's -::auto_path, and so any necessary change must be made by the script: -.RS -.PP -.CS - safe::interpAddToAccessPath foo /usr/local/TclHome/lib/extras/Img1.4.11 - - lassign [safe::interpConfigure foo -autoPath] DUM childAutoPath - lappend childAutoPath /usr/local/TclHome/lib/extras/Img1.4.11 - safe::interpConfigure foo -autoPath $childAutoPath -.CE -.RE .SH "SEE ALSO" -interp(n), library(n), load(n), package(n), pkg_mkIndex(n), source(n), -tm(n), unknown(n) +interp(n), library(n), load(n), package(n), source(n), unknown(n) .SH KEYWORDS -alias, auto\-loading, auto_mkindex, load, parent interpreter, safe -interpreter, child interpreter, source -'\" Local Variables: -'\" mode: nroff -'\" End: +alias, auto\-loading, auto_mkindex, load, master interpreter, safe +interpreter, slave interpreter, source |