Messages in this thread | | | Date | Mon, 11 Aug 2008 14:56:45 -0500 | From | "Serge E. Hallyn" <> | Subject | Re: [PATCH 3/4] integrity: Linux Integrity Module(LIM) |
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Quoting Mimi Zohar (zohar@us.ibm.com): > serue@linux.vnet.ibm.com wrote on 08/11/2008 01:02:55 PM: > > > Quoting Mimi Zohar (zohar@us.ibm.com): > > > Christoph Hellwig <hch@infradead.org> wrote on 08/09/2008 02:53:40 PM: > > > > > int vfs_permission(struct nameidata *nd, int mask) > > > > > { > > > > > - return inode_permission(nd->path.dentry->d_inode, mask); > > > > > + int retval; > > > > > + > > > > > + retval = inode_permission(nd->path.dentry->d_inode, mask); > > > > > + if (retval) > > > > > + return retval; > > > > > + return integrity_inode_permission(NULL, &nd->path, > > > > > + mask & (MAY_READ | MAY_WRITE | > > > > > + MAY_EXEC)); > > > > > } > > > > > > > > > > /** > > > > > @@ -306,7 +314,14 @@ int vfs_permission(struct nameidata *nd, > > > > > */ > > > > > int file_permission(struct file *file, int mask) > > > > > { > > > > > - return inode_permission(file->f_path.dentry->d_inode, mask); > > > > > + int retval; > > > > > + > > > > > + retval = inode_permission(file->f_path.dentry->d_inode, mask); > > > > > + if (retval) > > > > > + return retval; > > > > > + return integrity_inode_permission(file, NULL, > > > > > + mask & (MAY_READ | MAY_WRITE | > > > > > + MAY_EXEC)); > > > > > > > > Please put your hook into inode_permission. Note that in inode > > > > permission and lots of callers there is no path available so don't > pass > > > > it. Please pass the full MAY_FOO mask for new interfaces and do > > > > filtering that won't break if new ones are introduced. > > > > > > We started out with the integrity_inode_permission() hook call in > > > inode_permission(), but because of the removal of the nameidata > > > parameter in the last merge, based on discussions > > > http://marc.info/?l=linux-security-module&m=121797845308246&w=2, > > > the call to integrity_inode_permission() was moved up to the caller, > > > where either a file or path are available. Any suggestions? > > > > Mimi, can you explain exactly (and concisely) what you are doing with > > the pathname? > > IMA maintains a list of hash values of system sensitive files loaded > into the run-time of the system and extends a PCR with the hash value. > In order to calculate this hash value, IMA requires access to either > the file or the path, which currently is not accessible in > inode_permission().
So the usual question is, if I've done ln -s /etc/shadow /tmp/shadow will IMA do the right thing if I'm opening /tmp/shadow? Or will it only catch any writes I've done the next time someone (i.e. passwd) opens /etc/shadow?
thanks, -serge
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