Difference between revisions of "Data Validation"

Revision as of 02:48, 22 July 2015 (view source)

Taupecat (talk | contribs)

m (Sorry Brits & Canadians!)

← Older edit

Latest revision as of 17:05, 6 December 2022 (view source)

Milana cap (talk | contribs)

(Migrated to DevHub)

(8 intermediate revisions by 5 users not shown)

Line 1:

+

<!--

{{Languages|

+

}}

Line 59:

Line 61:

=== URLs ===

; <code>[[Function Reference/esc_url|esc_url]]( $url, (array) $protocols = null )</code> (since 2.8)

−

: Always use <code>esc_url</code> when sanitizing URLs (in text nodes, attribute nodes or anywhere else). Rejects URLs that do not have one of the provided ~~whitelisted~~ protocols (defaulting to <tt>http</tt>, <tt>https</tt>, <tt>ftp</tt>, <tt>ftps</tt>, <tt>mailto</tt>, <tt>news</tt>, <tt>irc</tt>, <tt>gopher</tt>, <tt>nntp</tt>, <tt>feed</tt>, and <tt>telnet</tt>), eliminates invalid characters, and removes dangerous characters. Replaces <code>clean_url()</code> which was deprecated in 3.0.

+

: Always use <code>esc_url</code> when sanitizing URLs (in text nodes, attribute nodes or anywhere else). Rejects URLs that do not have one of the provided protocols (defaulting to <tt>http</tt>, <tt>https</tt>, <tt>ftp</tt>, <tt>ftps</tt>, <tt>mailto</tt>, <tt>news</tt>, <tt>irc</tt>, <tt>gopher</tt>, <tt>nntp</tt>, <tt>feed</tt>, and <tt>telnet</tt>), eliminates invalid characters, and removes dangerous characters. Replaces <code>clean_url()</code> which was deprecated in 3.0.

: This function encodes characters as HTML entities: use it when generating an (X)HTML or XML document. Encodes ampersands (<tt>&</tt>) and single quotes (<tt>'</tt>) as numeric entity references (<tt>&#038, &#039</tt>).

; <code>[[Function Reference/esc_url_raw|esc_url_raw]]( $url, (array) $protocols = null )</code> (since 2.8)

Line 98:

Line 100:

=== Filesystem ===

; <code>[[Function Reference/validate_file|validate_file]]( (string) $filename, (array) $allowed_files = "" )</code>

−

: Used to prevent directory traversal attacks, or to test a filename against a ~~whitelist~~. Returns <tt>0</tt> if <code>$filename</code> represents a valid relative path. After validating, you <em>must</em> treat <code>$filename</code> as a relative path (i.e. you must prepend it with an absolute path), since something like <tt>/etc/hosts</tt> will validate with this function. Returns an integer greater than zero if the given path contains <tt>..</tt>, <tt>./</tt>, or <tt>:</tt>, or is not in the <code>$allowed_files</code> ~~whitelist~~. Be careful making boolean interpretations of the result, since <tt>false</tt> (0) indicates the filename has passed validation, whereas <tt>true</tt> (> 0) indicates failure.

+

: Used to prevent directory traversal attacks, or to test a filename against a safelist. Returns <tt>0</tt> if <code>$filename</code> represents a valid relative path. After validating, you <em>must</em> treat <code>$filename</code> as a relative path (i.e. you must prepend it with an absolute path), since something like <tt>/etc/hosts</tt> will validate with this function. Returns an integer greater than zero if the given path contains <tt>..</tt>, <tt>./</tt>, or <tt>:</tt>, or is not in the <code>$allowed_files</code> safelist. Be careful making boolean interpretations of the result, since <tt>false</tt> (0) indicates the filename has passed validation, whereas <tt>true</tt> (> 0) indicates failure.

=== HTTP Headers ===

−

Header splitting attacks are annoying since they are dependent on the HTTP client. WordPress has little need to include user generated content in HTTP headers, but when it does, WordPress typically uses [[#~~Whitelist~~|~~whitelisting~~]] for most of its HTTP headers.

+

Header splitting attacks are annoying since they are dependent on the HTTP client. WordPress has little need to include user-generated content in HTTP headers, but when it does, WordPress typically uses [[#Safelist|safelisting]] for most of its HTTP headers.

−

WordPress does use user generated content in HTTP Location headers, and provides sanitization for those.

+

WordPress does use user-generated content in HTTP Location headers and provides sanitization for those.

; <code>[[Function Reference/wp_redirect|wp_redirect]]($location, $status = 302)</code>

: A safe way to redirect to any URL. Ensures the resulting HTTP Location header is legitimate.

; <code>[[Function Reference/wp_safe_redirect|wp_safe_redirect]]($location, $status = 302)</code>

−

: Even safer. Only allows redirects to ~~whitelisted~~ domains.

+

: Even safer. Only allows redirects to safelisted domains.

== Input Validation ==

Line 121:

Line 123:

=== HTML ===

−

; <code>[~~[Function Reference~~/balanceTags|balanceTags]]( $html )</code> or <code>[~~[Function Reference~~/force_balance_tags|force_balance_tags]]( $html )</code>

+

; <code>[https://developer.wordpress.org/reference/functions/balanceTags/ balanceTags]( $html )</code> or <code>[https://developer.wordpress.org/reference/functions/force_balance_tags/ force_balance_tags]( $html )</code>

: Tries to make sure HTML tags are balanced so that valid XML is output.

−

; <code>[~~[Function Reference~~/tag_escape|tag_escape]]( $html_tag_name )</code>

+

; <code>[https://developer.wordpress.org/reference/functions/tag_escape/ tag_escape]( $html_tag_name )</code>

: Sanitizes an HTML tag name (does not escape anything, despite the name of the function).

−

; <code>[~~[Function Reference~~/sanitize_html_class|sanitize_html_class]]( $class, $fallback )</code>

+

; <code>[https://developer.wordpress.org/reference/functions/sanitize_html_class/ sanitize_html_class]( $class, $fallback )</code>

: Sanitizes a html classname to ensure it only contains valid characters. Strips the string down to A-Z,a-z,0-9,'-' if this results in an empty string then it will return the alternative value supplied.

Line 157:

Line 159:

There are several different philosophies about how validation should be done. Each is appropriate for different scenarios.

−

=== ~~Whitelist~~ ===

+

=== Safelist ===

Accept data only from a finite list of known and trusted values.

−

When comparing untrusted data against the ~~whitelist~~, it's important to make sure that strict type checking is used. Otherwise an attacker could craft input in a way that will pass the ~~whitelist~~ but still have a malicious effect.

+

When comparing untrusted data against the safelist, it's important to make sure that strict type checking is used. Otherwise an attacker could craft input in a way that will pass the safelist but still have a malicious effect.

==== Comparison Operator ====

Line 202:

Line 204:

</pre></code>

−

=== ~~Blacklist~~ ===

+

=== Blocklist ===

Reject data from finite list of known untrusted values. This is very rarely a good idea.

Line 233:

Line 235:

* [http://wp.tutsplus.com/tutorials/creative-coding/data-sanitization-and-validation-with-wordpress/ Data Sanitization and Validation With WordPress] by Stephen Harris

* [http://wordpress.tv/2011/01/29/mark-jaquith-theme-plugin-security/ Theme and Plugin Security] by Mark Jaquith

−

* [http://groups.google.com/group/wp-hackers/browse_thread/thread/8f1466febb168935?pli=1 wp_specialchars() vs attribute_escape() ( now esc_attr() ) and quote entity-encoding].

[[Category:Security]]

[[Category:WordPress Development]]

+

-->

+

Migrated to: https://developer.wordpress.org/apis/security/data-validation/

Codex

Difference between revisions of "Data Validation"

Latest revision as of 17:05, 6 December 2022

Codex Resources

@@ Line 1: / Line 1: @@
+<!--
 {{Languages|
 {{en|Data Validation}}
 {{ja|Data Validation}}
 {{ru|Валидация данных}}
+{{zh-tw|資料驗證}}
 }}
@@ Line 59: / Line 61: @@
 === URLs ===
 ; <code>[[Function Reference/esc_url|esc_url]]( $url, (array) $protocols = null )</code> (since 2.8)
-:	Always use <code>esc_url</code> when sanitizing URLs (in text nodes, attribute nodes or anywhere else).  Rejects URLs that do not have one of the provided whitelisted protocols (defaulting to <tt>http</tt>, <tt>https</tt>, <tt>ftp</tt>, <tt>ftps</tt>, <tt>mailto</tt>, <tt>news</tt>, <tt>irc</tt>, <tt>gopher</tt>, <tt>nntp</tt>, <tt>feed</tt>, and <tt>telnet</tt>), eliminates invalid characters, and removes dangerous characters. Replaces <code>clean_url()</code> which was deprecated in 3.0.
+:	Always use <code>esc_url</code> when sanitizing URLs (in text nodes, attribute nodes or anywhere else).  Rejects URLs that do not have one of the provided protocols (defaulting to <tt>http</tt>, <tt>https</tt>, <tt>ftp</tt>, <tt>ftps</tt>, <tt>mailto</tt>, <tt>news</tt>, <tt>irc</tt>, <tt>gopher</tt>, <tt>nntp</tt>, <tt>feed</tt>, and <tt>telnet</tt>), eliminates invalid characters, and removes dangerous characters. Replaces <code>clean_url()</code> which was deprecated in 3.0.
 : This function encodes characters as HTML entities: use it when generating an (X)HTML or XML document. Encodes ampersands (<tt>&</tt>) and single quotes (<tt>'</tt>) as numeric entity references (<tt>&#038, &#039</tt>).
 ; <code>[[Function Reference/esc_url_raw|esc_url_raw]]( $url, (array) $protocols = null )</code> (since 2.8)
@@ Line 98: / Line 100: @@
 === Filesystem ===
 ; <code>[[Function Reference/validate_file|validate_file]]( (string) $filename, (array) $allowed_files = "" )</code>
-:	Used to prevent directory traversal attacks, or to test a filename against a whitelist. Returns <tt>0</tt> if <code>$filename</code> represents a valid relative path. After validating, you <em>must</em> treat <code>$filename</code> as a relative path (i.e. you must prepend it with an absolute path), since something like <tt>/etc/hosts</tt> will validate with this function. Returns an integer greater than zero if the given path contains <tt>..</tt>, <tt>./</tt>, or <tt>:</tt>, or is not in the <code>$allowed_files</code> whitelist. Be careful making boolean interpretations of the result, since <tt>false</tt> (0) indicates the filename has passed validation, whereas <tt>true</tt> (> 0) indicates failure.
+:	Used to prevent directory traversal attacks, or to test a filename against a safelist. Returns <tt>0</tt> if <code>$filename</code> represents a valid relative path. After validating, you <em>must</em> treat <code>$filename</code> as a relative path (i.e. you must prepend it with an absolute path), since something like <tt>/etc/hosts</tt> will validate with this function. Returns an integer greater than zero if the given path contains <tt>..</tt>, <tt>./</tt>, or <tt>:</tt>, or is not in the <code>$allowed_files</code> safelist. Be careful making boolean interpretations of the result, since <tt>false</tt> (0) indicates the filename has passed validation, whereas <tt>true</tt> (> 0) indicates failure.
 === HTTP Headers ===
-Header splitting attacks are annoying since they are dependent on the HTTP client.  WordPress has little need to include user generated content in HTTP headers, but when it does, WordPress typically uses [[#Whitelist|whitelisting]] for most of its HTTP headers.
+Header splitting attacks are annoying since they are dependent on the HTTP client.  WordPress has little need to include user-generated content in HTTP headers, but when it does, WordPress typically uses [[#Safelist|safelisting]] for most of its HTTP headers.
-WordPress does use user generated content in HTTP Location headers, and provides sanitization for those.
+WordPress does use user-generated content in HTTP Location headers and provides sanitization for those.
 ; <code>[[Function Reference/wp_redirect|wp_redirect]]($location, $status = 302)</code>
 :	A safe way to redirect to any URL.  Ensures the resulting HTTP Location header is legitimate.
 ; <code>[[Function Reference/wp_safe_redirect|wp_safe_redirect]]($location, $status = 302)</code>
-:	Even safer.  Only allows redirects to whitelisted domains.
+:	Even safer.  Only allows redirects to safelisted domains.
 == Input Validation ==
@@ Line 121: / Line 123: @@
 === HTML ===
-; <code>[[Function Reference/balanceTags|balanceTags]]( $html )</code> or <code>[[Function Reference/force_balance_tags|force_balance_tags]]( $html )</code>
+; <code>[https://developer.wordpress.org/reference/functions/balanceTags/ balanceTags]( $html )</code> or <code>[https://developer.wordpress.org/reference/functions/force_balance_tags/ force_balance_tags]( $html )</code>
 : Tries to make sure HTML tags are balanced so that valid XML is output.
-; <code>[[Function Reference/tag_escape|tag_escape]]( $html_tag_name )</code>
+; <code>[https://developer.wordpress.org/reference/functions/tag_escape/ tag_escape]( $html_tag_name )</code>
 : Sanitizes an HTML tag name (does not escape anything, despite the name of the function).
-; <code>[[Function Reference/sanitize_html_class|sanitize_html_class]]( $class, $fallback )</code>
+; <code>[https://developer.wordpress.org/reference/functions/sanitize_html_class/ sanitize_html_class]( $class, $fallback )</code>
 : Sanitizes a html classname to ensure it only contains valid characters. Strips the string down to A-Z,a-z,0-9,'-' if this results in an empty string then it will return the alternative value supplied.
@@ Line 157: / Line 159: @@
 There are several different philosophies about how validation should be done.  Each is appropriate for different scenarios.
-=== Whitelist ===
+=== Safelist ===
 Accept data only from a finite list of known and trusted values.
-When comparing untrusted data against the whitelist, it's important to make sure that strict type checking is used. Otherwise an attacker could craft input in a way that will pass the whitelist but still have a malicious effect.
+When comparing untrusted data against the safelist, it's important to make sure that strict type checking is used. Otherwise an attacker could craft input in a way that will pass the safelist but still have a malicious effect.
 ==== Comparison Operator ====
@@ Line 202: / Line 204: @@
 </pre></code>
-=== Blacklist ===
+=== Blocklist ===
 Reject data from finite list of known untrusted values.  This is very rarely a good idea.
@@ Line 233: / Line 235: @@
 * [http://wp.tutsplus.com/tutorials/creative-coding/data-sanitization-and-validation-with-wordpress/ Data Sanitization and Validation With WordPress] by Stephen Harris
 * [http://wordpress.tv/2011/01/29/mark-jaquith-theme-plugin-security/ Theme and Plugin Security] by Mark Jaquith
-* [http://groups.google.com/group/wp-hackers/browse_thread/thread/8f1466febb168935?pli=1 wp_specialchars() vs attribute_escape() ( now esc_attr() ) and quote entity-encoding].
 [[Category:Security]]
 [[Category:WordPress Development]]
+-->
+Migrated to: https://developer.wordpress.org/apis/security/data-validation/