From 4bacc9c9234c7c8eec44f5ed4e960d9f96fa0f01 Mon Sep 17 00:00:00 2001 From: David Howells <dhowells@redhat.com> Date: Thu, 18 Jun 2015 14:32:31 +0100 Subject: overlayfs: Make f_path always point to the overlay and f_inode to the underlay 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). Using my union testsuite to set things up, before the patch I see: [root@andromeda union-testsuite]# bash 5</mnt/a/foo107 [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</mnt/a/foo107 [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 <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> --- fs/overlayfs/inode.c | 14 ++++++-------- fs/overlayfs/overlayfs.h | 1 + fs/overlayfs/super.c | 1 + 3 files changed, 8 insertions(+), 8 deletions(-) (limited to 'fs/overlayfs') 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) -- cgit v1.2.3