Date: Tue, 19 Sep 2006 22:00:07 -0700 From: Deomid Ryabkov <myself@rojer.pp.ru> To: freebsd-hackers@freebsd.org Subject: Re: Symlinks on read-only FS Message-ID: <4510CAD7.5080001@rojer.pp.ru> In-Reply-To: <10609200356.AA21953@pluto.rain.com> References: <10609200101.AA21405@pluto.rain.com> <4510AF6D.2060809@rojer.pp.ru> <10609200356.AA21953@pluto.rain.com>
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This is a cryptographically signed message in MIME format. --------------ms080601030103080802060906 Content-Type: text/plain; charset=KOI8-R; format=flowed Content-Transfer-Encoding: 7bit Perry Hutchison wrote: > So the sort of write access being validated here would be writing to > the symlink itself (i.e. the definition)? symlinks are dereferenced during name lookup and are not affected by the write mount options of the filesystems they reside on. you can open a file for write by accessing a symlink pointing to it, even though the symlink itself may reside on a read-only filesystem. and you can disregard what i said in my previous post: there's no interface to change the symlink after it was created. actually, i'm not sure there is a real-world case in which this code would be invoked with VLNK. checking write permissions on a symlink? access(2)/eaccess(2) dereference symlinks. but if, for whatever reason, someone calls VOP_ACCESS on read-only UFS filesystem, checking if writing to symlink itself is ok, it will be denied. which makes sense. -- Deomid Ryabkov aka Rojer myself@rojer.pp.ru rojer@sysadmins.ru ICQ: 8025844 --------------ms080601030103080802060906 Content-Type: application/x-pkcs7-signature; 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