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[PATCH] namei fixes (10/19)
In open_namei(), __follow_down() loop turned into __follow_mount(). Instead of if we are on a mountpoint dentry if O_NOFOLLOW checks fail drop path.dentry drop nd return do equivalent of follow_mount(&path.mnt, &path.dentry) nd->mnt = path.mnt we do if __follow_mount(path) had, indeed, traversed mountpoint /* now both nd->mnt and path.mnt are pinned down */ if O_NOFOLLOW checks fail drop path.dentry drop path.mnt drop nd return mntput(nd->mnt) nd->mnt = path.mnt Now __follow_down() can be folded into follow_down() - no other callers left. We need to reorder dput()/mntput() there - same problem as in follow_mount(). Equivalent transformation + fix for a bug in O_NOFOLLOW handling - we used to get -ELOOP if we had the same fs mounted on /foo and /bar, had something bound on /bar/baz and tried to open /foo/baz with O_NOFOLLOW. And fix of too-early-mntput() race in follow_down() Signed-off-by: Al Viro <viro@parcelfarce.linux.theplanet.co.uk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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parent
463ffb2e9d
commit
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1 changed files with 9 additions and 11 deletions
20
fs/namei.c
20
fs/namei.c
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@ -612,26 +612,21 @@ static int follow_mount(struct vfsmount **mnt, struct dentry **dentry)
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/* no need for dcache_lock, as serialization is taken care in
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/* no need for dcache_lock, as serialization is taken care in
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* namespace.c
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* namespace.c
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*/
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*/
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static inline int __follow_down(struct vfsmount **mnt, struct dentry **dentry)
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int follow_down(struct vfsmount **mnt, struct dentry **dentry)
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{
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{
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struct vfsmount *mounted;
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struct vfsmount *mounted;
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mounted = lookup_mnt(*mnt, *dentry);
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mounted = lookup_mnt(*mnt, *dentry);
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if (mounted) {
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if (mounted) {
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dput(*dentry);
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mntput(*mnt);
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mntput(*mnt);
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*mnt = mounted;
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*mnt = mounted;
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dput(*dentry);
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*dentry = dget(mounted->mnt_root);
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*dentry = dget(mounted->mnt_root);
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return 1;
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return 1;
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}
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}
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return 0;
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return 0;
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}
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}
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int follow_down(struct vfsmount **mnt, struct dentry **dentry)
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{
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return __follow_down(mnt,dentry);
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}
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static inline void follow_dotdot(struct vfsmount **mnt, struct dentry **dentry)
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static inline void follow_dotdot(struct vfsmount **mnt, struct dentry **dentry)
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{
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{
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while(1) {
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while(1) {
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@ -1498,11 +1493,14 @@ int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
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if (flag & O_EXCL)
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if (flag & O_EXCL)
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goto exit_dput;
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goto exit_dput;
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if (d_mountpoint(path.dentry)) {
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if (__follow_mount(&path)) {
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error = -ELOOP;
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error = -ELOOP;
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if (flag & O_NOFOLLOW)
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if (flag & O_NOFOLLOW) {
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goto exit_dput;
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dput(path.dentry);
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while (__follow_down(&path.mnt,&path.dentry) && d_mountpoint(path.dentry));
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mntput(path.mnt);
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goto exit;
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}
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mntput(nd->mnt);
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nd->mnt = path.mnt;
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nd->mnt = path.mnt;
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}
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}
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error = -ENOENT;
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error = -ENOENT;
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