The commit is pushed to "branch-rh7-3.10.0-229.7.2.vz7.9.x-ovz" and will appear
at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-229.7.2.vz7.9.18
------>
commit efef4deec8717884f05fedf9123dfd93ad33614b
Author: Andrey Ryabinin <aryabi...@virtuozzo.com>
Date: Mon Dec 28 17:52:15 2015 +0400
ve/fs: drop useless d_root_check()
d_root_check() takes the following locks in wrong order:
write_seqlock(&rename_lock);
br_read_lock(&vfsmount_lock);
thus we may endup with deadlock.
While we could fix it by taking these locks in reverse
order, it would be better to just delete this function.
d_root_check() is a leftover from pre-mount namespace days,
we don't need it today.
https://jira.sw.ru/browse/PSBM-41919
Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com>
Acked-by: Andrew Vagin <ava...@virtuozzo.com>
---
fs/dcache.c | 53 --------------------------------------------------
fs/proc/base.c | 31 +++++++++--------------------
fs/proc/fd.c | 2 +-
include/linux/dcache.h | 1 -
4 files changed, 10 insertions(+), 77 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index a4f60d1..b5119e3 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -3220,59 +3220,6 @@ Elong:
return ERR_PTR(-ENAMETOOLONG);
}
-/**
- * d_root_check - checks if dentry is accessible from current's fs root
- * @dentry: dentry to be verified
- * @vfsmnt: vfsmnt to which the dentry belongs
- */
-int d_root_check(struct path *path)
-{
- struct dentry *dentry = path->dentry;
- struct vfsmount *vfsmnt = path->mnt;
- struct mount *mnt = real_mount(vfsmnt);
- struct path root;
- int error = 0;
-
- if (ve_is_super(get_exec_env()))
- return 0;
-
- if (path->dentry->d_op && path->dentry->d_op->d_dname)
- return 0;
-
- /*
- * If we meet disconnected entry, it's allowed
- * to proceed, it comes from special allocations
- * such as opening by file handle, where dentry
- * formed directly from the inode opened.
- */
- if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
- return 0;
-
- get_fs_root(current->fs, &root);
- write_seqlock(&rename_lock);
- br_read_lock(&vfsmount_lock);
- while (dentry != root.dentry || vfsmnt != root.mnt) {
- if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
- /* Global root? */
- if (!mnt_has_parent(mnt)) {
- if (mnt->mnt_ns == ve0.ve_ns->mnt_ns)
- error = -EACCES;
- break;
- }
- dentry = mnt->mnt_mountpoint;
- mnt = mnt->mnt_parent;
- vfsmnt = &mnt->mnt;
- continue;
- }
- dentry = dentry->d_parent;
- }
- br_read_unlock(&vfsmount_lock);
- write_sequnlock(&rename_lock);
- path_put(&root);
-
- return error;
-}
-
/*
* NOTE! The user-level library version returns a
* character pointer. The kernel system call just
diff --git a/fs/proc/base.c b/fs/proc/base.c
index b597b01..e9044e6 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -165,13 +165,9 @@ static int get_task_root(struct task_struct *task, struct
path *root)
task_lock(task);
if (task->fs) {
get_fs_root(task->fs, root);
- task_unlock(task);
-
- result = d_root_check(root);
- if (result)
- path_put(root);
- } else
- task_unlock(task);
+ result = 0;
+ }
+ task_unlock(task);
return result;
}
@@ -184,13 +180,9 @@ static int proc_cwd_link(struct dentry *dentry, struct
path *path)
task_lock(task);
if (task->fs) {
get_fs_pwd(task->fs, path);
- task_unlock(task);
-
- result = d_root_check(path);
- if (result)
- path_put(path);
- } else
- task_unlock(task);
+ result = 0;
+ }
+ task_unlock(task);
put_task_struct(task);
}
return result;
@@ -1491,15 +1483,10 @@ static int proc_exe_link(struct dentry *dentry, struct
path *exe_path)
exe_file = get_mm_exe_file(mm);
mmput(mm);
if (exe_file) {
- int result;
-
- result = d_root_check(&exe_file->f_path);
- if (result == 0) {
- *exe_path = exe_file->f_path;
- path_get(&exe_file->f_path);
- }
+ *exe_path = exe_file->f_path;
+ path_get(&exe_file->f_path);
fput(exe_file);
- return result;
+ return 0;
} else
return -ENOENT;
}
diff --git a/fs/proc/fd.c b/fs/proc/fd.c
index cf657f7..911dac9 100644
--- a/fs/proc/fd.c
+++ b/fs/proc/fd.c
@@ -158,7 +158,7 @@ static int proc_fd_link(struct dentry *dentry, struct path
*path)
spin_lock(&files->file_lock);
fd_file = fcheck_files(files, fd);
ret = -EACCES;
- if (fd_file && !d_root_check(&fd_file->f_path)) {
+ if (fd_file) {
*path = fd_file->f_path;
path_get(&fd_file->f_path);
ret = 0;
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 56766a1..4a44f37 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -333,7 +333,6 @@ extern char *d_absolute_path(const struct path *, char *,
int);
extern char *d_path(const struct path *, char *, int);
extern char *dentry_path_raw(struct dentry *, char *, int);
extern char *dentry_path(struct dentry *, char *, int);
-extern int d_root_check(struct path *path);
/* Allocation counts.. */
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