From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755040AbbGTMmh (ORCPT ); Mon, 20 Jul 2015 08:42:37 -0400 Received: from forward-corp1m.cmail.yandex.net ([5.255.216.100]:48862 "EHLO forward-corp1m.cmail.yandex.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754729AbbGTMme (ORCPT ); Mon, 20 Jul 2015 08:42:34 -0400 Authentication-Results: smtpcorp4.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Message-ID: <55ACECB1.1030806@yandex-team.ru> Date: Mon, 20 Jul 2015 15:42:25 +0300 From: Konstantin Khlebnikov User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: David Howells , sds@tycho.nsa.gov, viro@zeniv.linux.org.uk, miklos@szeredi.hu CC: linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-unionfs@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/8] overlayfs: Make f_path always point to the overlay and f_inode to the underlay References: <20150618133215.12722.70352.stgit@warthog.procyon.org.uk> <20150618133231.12722.48177.stgit@warthog.procyon.org.uk> In-Reply-To: <20150618133231.12722.48177.stgit@warthog.procyon.org.uk> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18.06.2015 16:32, David Howells wrote: > Make file->f_path always point to the overlay dentry so that the path in > /proc/pid/fd is correct and to ensure that label-based LSMs have access to the > overlay as well as the underlay (path-based LSMs probably don't need it). Cool. Looks like this fixes MNT_NOEXEC,MNT_NOSUID,MNT_NODEV for overlayfs. But probably breaks MNT_LOCK_NOEXEC/SUID/DEV. > > Using my union testsuite to set things up, before the patch I see: > > [root@andromeda union-testsuite]# bash 5 [root@andromeda union-testsuite]# ls -l /proc/$$/fd/ > ... > lr-x------. 1 root root 64 Jun 5 14:38 5 -> /a/foo107 > [root@andromeda union-testsuite]# stat /mnt/a/foo107 > ... > Device: 23h/35d Inode: 13381 Links: 1 > ... > [root@andromeda union-testsuite]# stat -L /proc/$$/fd/5 > ... > Device: 23h/35d Inode: 13381 Links: 1 > ... > > After the patch: > > [root@andromeda union-testsuite]# bash 5 [root@andromeda union-testsuite]# ls -l /proc/$$/fd/ > ... > lr-x------. 1 root root 64 Jun 5 14:22 5 -> /mnt/a/foo107 > [root@andromeda union-testsuite]# stat /mnt/a/foo107 > ... > Device: 23h/35d Inode: 40346 Links: 1 > ... > [root@andromeda union-testsuite]# stat -L /proc/$$/fd/5 > ... > Device: 23h/35d Inode: 40346 Links: 1 > ... > > Note the change in where /proc/$$/fd/5 points to in the ls command. It was > pointing to /a/foo107 (which doesn't exist) and now points to /mnt/a/foo107 > (which is correct). > > The inode accessed, however, is the lower layer. The union layer is on device > 25h/37d and the upper layer on 24h/36d. > > Signed-off-by: David Howells > --- > > fs/dcache.c | 5 ++++- > fs/internal.h | 1 + > fs/open.c | 49 ++++++++++++++++++++++++---------------------- > fs/overlayfs/inode.c | 14 ++++++------- > fs/overlayfs/overlayfs.h | 1 + > fs/overlayfs/super.c | 1 + > include/linux/dcache.h | 2 ++ > include/linux/fs.h | 2 -- > 8 files changed, 41 insertions(+), 34 deletions(-) > > diff --git a/fs/dcache.c b/fs/dcache.c > index 37b5afdaf698..c4ce35110704 100644 > --- a/fs/dcache.c > +++ b/fs/dcache.c > @@ -1673,7 +1673,8 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) > DCACHE_OP_COMPARE | > DCACHE_OP_REVALIDATE | > DCACHE_OP_WEAK_REVALIDATE | > - DCACHE_OP_DELETE )); > + DCACHE_OP_DELETE | > + DCACHE_OP_SELECT_INODE)); > dentry->d_op = op; > if (!op) > return; > @@ -1689,6 +1690,8 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) > dentry->d_flags |= DCACHE_OP_DELETE; > if (op->d_prune) > dentry->d_flags |= DCACHE_OP_PRUNE; > + if (op->d_select_inode) > + dentry->d_flags |= DCACHE_OP_SELECT_INODE; > > } > EXPORT_SYMBOL(d_set_d_op); > diff --git a/fs/internal.h b/fs/internal.h > index 01dce1d1476b..4d5af583ab03 100644 > --- a/fs/internal.h > +++ b/fs/internal.h > @@ -107,6 +107,7 @@ extern struct file *do_file_open_root(struct dentry *, struct vfsmount *, > extern long do_handle_open(int mountdirfd, > struct file_handle __user *ufh, int open_flag); > extern int open_check_o_direct(struct file *f); > +extern int vfs_open(const struct path *, struct file *, const struct cred *); > > /* > * inode.c > diff --git a/fs/open.c b/fs/open.c > index e0250bdcc440..b1c5823b7f11 100644 > --- a/fs/open.c > +++ b/fs/open.c > @@ -678,18 +678,18 @@ int open_check_o_direct(struct file *f) > } > > static int do_dentry_open(struct file *f, > + struct inode *inode, > int (*open)(struct inode *, struct file *), > const struct cred *cred) > { > static const struct file_operations empty_fops = {}; > - struct inode *inode; > int error; > > f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK | > FMODE_PREAD | FMODE_PWRITE; > > path_get(&f->f_path); > - inode = f->f_inode = f->f_path.dentry->d_inode; > + f->f_inode = inode; > f->f_mapping = inode->i_mapping; > > if (unlikely(f->f_flags & O_PATH)) { > @@ -793,7 +793,8 @@ int finish_open(struct file *file, struct dentry *dentry, > BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ > > file->f_path.dentry = dentry; > - error = do_dentry_open(file, open, current_cred()); > + error = do_dentry_open(file, d_backing_inode(dentry), open, > + current_cred()); > if (!error) > *opened |= FILE_OPENED; > > @@ -822,6 +823,28 @@ int finish_no_open(struct file *file, struct dentry *dentry) > } > EXPORT_SYMBOL(finish_no_open); > > +/** > + * vfs_open - open the file at the given path > + * @path: path to open > + * @file: newly allocated file with f_flag initialized > + * @cred: credentials to use > + */ > +int vfs_open(const struct path *path, struct file *file, > + const struct cred *cred) > +{ > + struct dentry *dentry = path->dentry; > + struct inode *inode = dentry->d_inode; > + > + file->f_path = *path; > + if (dentry->d_flags & DCACHE_OP_SELECT_INODE) { > + inode = dentry->d_op->d_select_inode(dentry, file->f_flags); > + if (IS_ERR(inode)) > + return PTR_ERR(inode); > + } > + > + return do_dentry_open(file, inode, NULL, cred); > +} > + > struct file *dentry_open(const struct path *path, int flags, > const struct cred *cred) > { > @@ -853,26 +876,6 @@ struct file *dentry_open(const struct path *path, int flags, > } > EXPORT_SYMBOL(dentry_open); > > -/** > - * vfs_open - open the file at the given path > - * @path: path to open > - * @filp: newly allocated file with f_flag initialized > - * @cred: credentials to use > - */ > -int vfs_open(const struct path *path, struct file *filp, > - const struct cred *cred) > -{ > - struct inode *inode = path->dentry->d_inode; > - > - if (inode->i_op->dentry_open) > - return inode->i_op->dentry_open(path->dentry, filp, cred); > - else { > - filp->f_path = *path; > - return do_dentry_open(filp, NULL, cred); > - } > -} > -EXPORT_SYMBOL(vfs_open); > - > static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op) > { > int lookup_flags = 0; > diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c > index 21079d1ca2aa..f140e3dbfb7b 100644 > --- a/fs/overlayfs/inode.c > +++ b/fs/overlayfs/inode.c > @@ -337,31 +337,30 @@ static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type, > return true; > } > > -static int ovl_dentry_open(struct dentry *dentry, struct file *file, > - const struct cred *cred) > +struct inode *ovl_d_select_inode(struct dentry *dentry, unsigned file_flags) > { > int err; > struct path realpath; > enum ovl_path_type type; > > type = ovl_path_real(dentry, &realpath); > - if (ovl_open_need_copy_up(file->f_flags, type, realpath.dentry)) { > + if (ovl_open_need_copy_up(file_flags, type, realpath.dentry)) { > err = ovl_want_write(dentry); > if (err) > - return err; > + return ERR_PTR(err); > > - if (file->f_flags & O_TRUNC) > + if (file_flags & O_TRUNC) > err = ovl_copy_up_last(dentry, NULL, true); > else > err = ovl_copy_up(dentry); > ovl_drop_write(dentry); > if (err) > - return err; > + return ERR_PTR(err); > > ovl_path_upper(dentry, &realpath); > } > > - return vfs_open(&realpath, file, cred); > + return d_backing_inode(realpath.dentry); > } > > static const struct inode_operations ovl_file_inode_operations = { > @@ -372,7 +371,6 @@ static const struct inode_operations ovl_file_inode_operations = { > .getxattr = ovl_getxattr, > .listxattr = ovl_listxattr, > .removexattr = ovl_removexattr, > - .dentry_open = ovl_dentry_open, > }; > > static const struct inode_operations ovl_symlink_inode_operations = { > diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h > index 17ac5afc9ffb..ea5a40b06e3a 100644 > --- a/fs/overlayfs/overlayfs.h > +++ b/fs/overlayfs/overlayfs.h > @@ -173,6 +173,7 @@ ssize_t ovl_getxattr(struct dentry *dentry, const char *name, > void *value, size_t size); > ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size); > int ovl_removexattr(struct dentry *dentry, const char *name); > +struct inode *ovl_d_select_inode(struct dentry *dentry, unsigned file_flags); > > struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, > struct ovl_entry *oe); > diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c > index 5f0d1993e6e3..84c5e27fbfd9 100644 > --- a/fs/overlayfs/super.c > +++ b/fs/overlayfs/super.c > @@ -275,6 +275,7 @@ static void ovl_dentry_release(struct dentry *dentry) > > static const struct dentry_operations ovl_dentry_operations = { > .d_release = ovl_dentry_release, > + .d_select_inode = ovl_d_select_inode, > }; > > static struct ovl_entry *ovl_alloc_entry(unsigned int numlower) > diff --git a/include/linux/dcache.h b/include/linux/dcache.h > index df334cbacc6d..167ec0934049 100644 > --- a/include/linux/dcache.h > +++ b/include/linux/dcache.h > @@ -160,6 +160,7 @@ struct dentry_operations { > char *(*d_dname)(struct dentry *, char *, int); > struct vfsmount *(*d_automount)(struct path *); > int (*d_manage)(struct dentry *, bool); > + struct inode *(*d_select_inode)(struct dentry *, unsigned); > } ____cacheline_aligned; > > /* > @@ -225,6 +226,7 @@ struct dentry_operations { > > #define DCACHE_MAY_FREE 0x00800000 > #define DCACHE_FALLTHRU 0x01000000 /* Fall through to lower layer */ > +#define DCACHE_OP_SELECT_INODE 0x02000000 /* Unioned entry: dcache op selects inode */ > > extern seqlock_t rename_lock; > > diff --git a/include/linux/fs.h b/include/linux/fs.h > index b577e801b4af..2bd77e10e8e5 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -1641,7 +1641,6 @@ struct inode_operations { > int (*set_acl)(struct inode *, struct posix_acl *, int); > > /* WARNING: probably going away soon, do not use! */ > - int (*dentry_open)(struct dentry *, struct file *, const struct cred *); > } ____cacheline_aligned; > > ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector, > @@ -2194,7 +2193,6 @@ extern struct file *file_open_name(struct filename *, int, umode_t); > extern struct file *filp_open(const char *, int, umode_t); > extern struct file *file_open_root(struct dentry *, struct vfsmount *, > const char *, int); > -extern int vfs_open(const struct path *, struct file *, const struct cred *); > extern struct file * dentry_open(const struct path *, int, const struct cred *); > extern int filp_close(struct file *, fl_owner_t id); > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >