From 1d88f183734c0d916428911df006e645a6162cab Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 20 Jul 2017 11:08:21 +0200 Subject: ovl: fix xattr get and set with selinux inode_doinit_with_dentry() in SELinux wants to read the upper inode's xattr to get security label, and ovl_xattr_get() calls ovl_dentry_real(), which depends on dentry->d_inode, but d_inode is null and not initialized yet at this point resulting in an Oops. Fix by getting the upperdentry info from the inode directly in this case. Reported-by: Eryu Guan Fixes: 09d8b586731b ("ovl: move __upperdentry to ovl_inode") Signed-off-by: Miklos Szeredi --- fs/overlayfs/inode.c | 32 +++++++++++++++++--------------- fs/overlayfs/overlayfs.h | 7 ++++--- fs/overlayfs/super.c | 8 ++++---- fs/overlayfs/util.c | 7 ++++++- 4 files changed, 31 insertions(+), 23 deletions(-) (limited to 'fs') diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index 69f4fc26ee398..5bc71642b2260 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -202,37 +202,38 @@ bool ovl_is_private_xattr(const char *name) sizeof(OVL_XATTR_PREFIX) - 1) == 0; } -int ovl_xattr_set(struct dentry *dentry, const char *name, const void *value, - size_t size, int flags) +int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name, + const void *value, size_t size, int flags) { int err; - struct path realpath; - enum ovl_path_type type = ovl_path_real(dentry, &realpath); + struct dentry *upperdentry = ovl_i_dentry_upper(inode); + struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry); const struct cred *old_cred; err = ovl_want_write(dentry); if (err) goto out; - if (!value && !OVL_TYPE_UPPER(type)) { - err = vfs_getxattr(realpath.dentry, name, NULL, 0); + if (!value && !upperdentry) { + err = vfs_getxattr(realdentry, name, NULL, 0); if (err < 0) goto out_drop_write; } - err = ovl_copy_up(dentry); - if (err) - goto out_drop_write; + if (!upperdentry) { + err = ovl_copy_up(dentry); + if (err) + goto out_drop_write; - if (!OVL_TYPE_UPPER(type)) - ovl_path_upper(dentry, &realpath); + realdentry = ovl_dentry_upper(dentry); + } old_cred = ovl_override_creds(dentry->d_sb); if (value) - err = vfs_setxattr(realpath.dentry, name, value, size, flags); + err = vfs_setxattr(realdentry, name, value, size, flags); else { WARN_ON(flags != XATTR_REPLACE); - err = vfs_removexattr(realpath.dentry, name); + err = vfs_removexattr(realdentry, name); } revert_creds(old_cred); @@ -242,12 +243,13 @@ out: return err; } -int ovl_xattr_get(struct dentry *dentry, const char *name, +int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name, void *value, size_t size) { - struct dentry *realdentry = ovl_dentry_real(dentry); ssize_t res; const struct cred *old_cred; + struct dentry *realdentry = + ovl_i_dentry_upper(inode) ?: ovl_dentry_lower(dentry); old_cred = ovl_override_creds(dentry->d_sb); res = vfs_getxattr(realdentry, name, value, size); diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index 032120a761c4c..e927a62c97ae3 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -200,6 +200,7 @@ enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path); struct dentry *ovl_dentry_upper(struct dentry *dentry); struct dentry *ovl_dentry_lower(struct dentry *dentry); struct dentry *ovl_dentry_real(struct dentry *dentry); +struct dentry *ovl_i_dentry_upper(struct inode *inode); struct inode *ovl_inode_upper(struct inode *inode); struct inode *ovl_inode_lower(struct inode *inode); struct inode *ovl_inode_real(struct inode *inode); @@ -271,9 +272,9 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr); int ovl_getattr(const struct path *path, struct kstat *stat, u32 request_mask, unsigned int flags); int ovl_permission(struct inode *inode, int mask); -int ovl_xattr_set(struct dentry *dentry, const char *name, const void *value, - size_t size, int flags); -int ovl_xattr_get(struct dentry *dentry, const char *name, +int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name, + const void *value, size_t size, int flags); +int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name, void *value, size_t size); ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size); struct posix_acl *ovl_get_acl(struct inode *inode, int type); diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index c88493b01d8db..d86e89f972016 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -692,7 +692,7 @@ ovl_posix_acl_xattr_get(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, const char *name, void *buffer, size_t size) { - return ovl_xattr_get(dentry, handler->name, buffer, size); + return ovl_xattr_get(dentry, inode, handler->name, buffer, size); } static int __maybe_unused @@ -742,7 +742,7 @@ ovl_posix_acl_xattr_set(const struct xattr_handler *handler, return err; } - err = ovl_xattr_set(dentry, handler->name, value, size, flags); + err = ovl_xattr_set(dentry, inode, handler->name, value, size, flags); if (!err) ovl_copyattr(ovl_inode_real(inode), inode); @@ -772,7 +772,7 @@ static int ovl_other_xattr_get(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, const char *name, void *buffer, size_t size) { - return ovl_xattr_get(dentry, name, buffer, size); + return ovl_xattr_get(dentry, inode, name, buffer, size); } static int ovl_other_xattr_set(const struct xattr_handler *handler, @@ -780,7 +780,7 @@ static int ovl_other_xattr_set(const struct xattr_handler *handler, const char *name, const void *value, size_t size, int flags) { - return ovl_xattr_set(dentry, name, value, size, flags); + return ovl_xattr_set(dentry, inode, name, value, size, flags); } static const struct xattr_handler __maybe_unused diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c index c492ba75c6595..f46ad75dc96af 100644 --- a/fs/overlayfs/util.c +++ b/fs/overlayfs/util.c @@ -157,9 +157,14 @@ struct dentry *ovl_dentry_real(struct dentry *dentry) return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry); } +struct dentry *ovl_i_dentry_upper(struct inode *inode) +{ + return ovl_upperdentry_dereference(OVL_I(inode)); +} + struct inode *ovl_inode_upper(struct inode *inode) { - struct dentry *upperdentry = ovl_upperdentry_dereference(OVL_I(inode)); + struct dentry *upperdentry = ovl_i_dentry_upper(inode); return upperdentry ? d_inode(upperdentry) : NULL; } -- cgit v1.2.3