From mboxrd@z Thu Jan 1 00:00:00 1970 From: viro@ZenIV.linux.org.uk (Al Viro) Date: Fri, 22 Jun 2018 15:52:59 +0100 Subject: 4.18-rc1 regression in /proc/self xattr handling In-Reply-To: <020be8a4-961b-b92f-7ee9-3c439d629338@schaufler-ca.com> References: <020be8a4-961b-b92f-7ee9-3c439d629338@schaufler-ca.com> Message-ID: <20180622145259.GZ30522@ZenIV.linux.org.uk> To: linux-security-module@vger.kernel.org List-Id: linux-security-module.vger.kernel.org On Fri, Jun 22, 2018 at 07:37:00AM -0700, Casey Schaufler wrote: > There is a regression in behavior regarding xattrs in /proc after: > > commit 1bbc55131e59bd099fdc568d3aa0b42634dbd188 > Author: Al Viro > Date: Wed May 2 21:26:16 2018 -0400 > > procfs: get rid of ancient BS in pid_revalidate() uses > > > Prior to this change lgetxattr() would provide the correct attributes > for entries in /proc. With this change I see that while the behavior > remains correct if the procid is specified, it is not when "self" is > used. On a system with Smack enabled, where the shell has the Smack label > "Crackle" I see: > > [root at localhost linux]# attr -S -g SMACK64 /proc/self/attr/current > Attribute "SMACK64" had a 1 byte value for /proc/self/attr/current: > _ > [root at localhost linux]# attr -S -g SMACK64 /proc/$BASHPID/attr/current > Attribute "SMACK64" had a 7 byte value for /proc/1716/attr/current: > Crackle Wait a sec - the former will be that of attr, the latter - of bash; it's not the same file at all. > These should be the same, and in the past have been. I don't know > what SELinux expects as far as attributes in /proc, so I can't say > if the problem is manifest with SELinux. Very interesting... About the only thing changed here seems to be the relative order of smack_d_instantiate() and smack_task_to_inode()... Would setting SMK_INODE_INSTANT in isp->smk_flags in smack_task_to_inode() be the right thing to do, anyway? -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html