A NOTE has been added to this issue. ====================================================================== https://austingroupbugs.net/view.php?id=561 ====================================================================== Reported By: eblake Assigned To: ajosey ====================================================================== Project: 1003.1(2008)/Issue 7 Issue ID: 561 Category: System Interfaces Type: Error Severity: Objection Priority: normal Status: Under Review Name: Eric Blake Organization: Red Hat User Reference: ebb.sockaddr_un Section: <sys/un.h> Page Number: 403 Line Number: 13515 Interp Status: --- Final Accepted Text: ====================================================================== Date Submitted: 2012-05-03 16:14 UTC Last Modified: 2022-11-28 16:24 UTC ====================================================================== Summary: NUL-termination of sun_path in Unix sockets ====================================================================== Relationships ID Summary ---------------------------------------------------------------------- related to 0001593 specify whether struct sockaddr_un.sun_... ======================================================================
---------------------------------------------------------------------- (0006085) geoffclare (manager) - 2022-11-28 16:24 https://austingroupbugs.net/view.php?id=561#c6085 ---------------------------------------------------------------------- Page and line numbers are for Issue 8 draft 2.1. At page 403 line 13894 section <sys/un.h> DESCRIPTION, change: <blockquote><tt>char sun_path[]</tt> Socket pathname.</blockquote> to: <blockquote><tt>char sun_path[<i>size</i>]</tt> Socket pathname storage. The <i>sun_path</i> member shall be the last member of the <b>sockaddr_un</b> structure, where <i>size</i> shall be an implementation-provided constant size of at least 92 bytes. This size value need not be accessible as a constant available for use in the application namespace.</blockquote> At page 403 line 13899 section <sys/un.h> APPLICATION USAGE, change: <blockquote>The size of <i>sun_path</i> has intentionally been left undefined. This is because different implementations use different sizes. For example, 4.3 BSD uses a size of 108, and 4.4 BSD uses a size of 104. Since most implementations originate from BSD versions, the size is typically in the range 92 to 108.</blockquote> to: <blockquote>The size of <i>sun_path</i> is required to be constant, but intentionally does not have a specified name for that constant. Historically, different implementations used different sizes. For example, 4.3 BSD used a size of 108, and 4.4 BSD used a size of 104. Since most implementations originate from BSD versions, the size is typically in the range 92 to 108. However, because <i>sun_path</i> is required to be the last member of the struct, an application can deduce the size by using <tt>sizeof(struct sockaddr_un) - offsetof(struct sockaddr_un, sun_path)</tt>.</blockquote> At page 403 line 13911 section <sys/un.h> RATIONALE, change from "None" to: <blockquote>Some implementations expose a macro <tt>SUN_LEN</tt> for the size of a pathname stored in <tt>sun_path</tt>. However, this was not widely adopted, and differences on how a terminating NUL byte is interpreted between implementations did not make it worth standardizing.</blockquote> After page 543 line 19233 section accept() and page 1745 line 57250 section recvfrom(), add to APPLICATION USAGE, and at page 1055 line 36136 section getpeername() and page 1081 line 36940 section getsockname(), change APPLICATION USAGE from "None" to: <blockquote>For AF_UNIX sockets, it is recommended that <i>address</i> points to a buffer of length greater than <tt>sizeof(struct sockaddr_un)</tt> which has been initialized with null bytes. That way, even if the implementation supports the use of all bytes of <i>sun_path</i> without a terminating null byte, the larger buffer guarantees that the <i>sun_path</i> member can then be passed to other interfaces that expect a null-terminated string. If no truncation occurred based on the input value of <i>address_len</i>, It is unspecified whether the returned <i>address_len</i> will be <tt>sizeof(struct sockaddr_un)</tt>, or merely a value at least as large as <tt>offsetof(struct sockaddr_un, sun_path)</tt> plus the number of non-null bytes stored in <i>sun_path</i>.</blockquote> At page 604 line 21124 section bind() DESCRIPTION, after applying bug 1605 change: <blockquote>If the address family of the socket is AF_UNIX and the pathname in <i>address</i> names an existing file, including a symbolic link, <i>bind</i>() shall treat the address as already in use; see ERRORS below.</blockquote> to: <blockquote>If the address family of the socket is AF_UNIX, the application shall ensure that a null terminator after the pathname is included in the <i>sun_path</i> member of <i>address</i> as a <b>sockaddr_un</b> structure, and that <i>address_len</i> is at least <tt>offsetof(struct sockaddr_un, sun_path) + 1</tt> plus the length of the pathname. If the pathname in the <i>sun_path</i> member of <i>address</i> names an existing file, including a symbolic link, <i>bind</i>( ) shall treat the address as already in use; see ERRORS below.</blockquote> After page 606 line 21209 section bind() add to APPLICATION USAGE, and after page 686 line 23737 section connect() add to APPLICATION USAGE: <blockquote>For AF_UNIX sockets, some implementations support an extension where<i>address_len</i> does not have to include a null terminator for the pathname stored in <i>sun_path</i>, which in turn allows a pathname to be one byte longer. However, such usage is not portable, and carries a risk of accessing beyond the intended bounds of the pathname length.</blockquote> After page 684 line 23647 section connect() add to DESCRIPTION: <blockquote>If the address family of the socket is AF_UNIX, the application shall ensure that a null terminator after the pathname is included in the <i>sun_path</i> member of <i>address</i> as a <b>sockaddr_un</b> structure, and that <i>address_len</i> is at least <tt>offsetof(struct sockaddr_un, sun_path) + 1</tt> plus the length of the pathname. </blockquote> After page 1836 line 60177 section sendto() add to DESCRIPTION: <blockquote>If the address family of the socket is AF_UNIX, the application shall ensure that a null terminator after the pathname is included in the <i>sun_path</i> member of <i>dest_addr</i> as a <b>sockaddr_un</b> structure, and that <i>dest_len</i> is at least <tt>offsetof(struct sockaddr_un, sun_path) + 1</tt> plus the length of the pathname.</blockquote> After page 1838 line 60255 section sendto() add to APPLICATION USAGE: <blockquote>For AF_UNIX sockets, some implementations support an extension where<i>dest_len</i> does not have to include a null terminator for the pathname stored in <i>sun_path</i>, which in turn allows a pathname to be one byte longer. However, such usage is not portable, and carries a risk of accessing beyond the intended bounds of the pathname length.</blockquote> Issue History Date Modified Username Field Change ====================================================================== 2012-05-03 16:14 eblake New Issue 2012-05-03 16:14 eblake Status New => Under Review 2012-05-03 16:14 eblake Assigned To => ajosey 2012-05-03 16:14 eblake Name => Eric Blake 2012-05-03 16:14 eblake Organization => Red Hat 2012-05-03 16:14 eblake User Reference => ebb.sockaddr_un 2012-05-03 16:14 eblake Section => <sys/un.h> 2012-05-03 16:14 eblake Page Number => 403 2012-05-03 16:14 eblake Line Number => 13515 2012-05-03 16:14 eblake Interp Status => --- 2012-05-03 17:23 mdempsky Note Added: 0001226 2012-05-03 17:33 eblake Note Added: 0001227 2012-05-03 17:39 mdempsky Note Added: 0001228 2012-05-04 22:21 mkerrisk Note Added: 0001233 2012-06-04 14:15 codonell Issue Monitored: codonell 2022-07-20 20:34 eblake Relationship added related to 0001593 2022-11-28 16:24 geoffclare Note Added: 0006085 ======================================================================
