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-rw-r--r--fs/namei.c95
-rw-r--r--include/linux/namei.h1
2 files changed, 44 insertions, 52 deletions
diff --git a/fs/namei.c b/fs/namei.c
index 0bebd13..8ee7785 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -401,9 +401,11 @@ static int nameidata_drop_rcu(struct nameidata *nd)
{
struct fs_struct *fs = current->fs;
struct dentry *dentry = nd->path.dentry;
+ int want_root = 0;
BUG_ON(!(nd->flags & LOOKUP_RCU));
- if (nd->root.mnt) {
+ if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
+ want_root = 1;
spin_lock(&fs->lock);
if (nd->root.mnt != fs->root.mnt ||
nd->root.dentry != fs->root.dentry)
@@ -414,7 +416,7 @@ static int nameidata_drop_rcu(struct nameidata *nd)
goto err;
BUG_ON(nd->inode != dentry->d_inode);
spin_unlock(&dentry->d_lock);
- if (nd->root.mnt) {
+ if (want_root) {
path_get(&nd->root);
spin_unlock(&fs->lock);
}
@@ -427,7 +429,7 @@ static int nameidata_drop_rcu(struct nameidata *nd)
err:
spin_unlock(&dentry->d_lock);
err_root:
- if (nd->root.mnt)
+ if (want_root)
spin_unlock(&fs->lock);
return -ECHILD;
}
@@ -454,9 +456,11 @@ static int nameidata_dentry_drop_rcu(struct nameidata *nd, struct dentry *dentry
{
struct fs_struct *fs = current->fs;
struct dentry *parent = nd->path.dentry;
+ int want_root = 0;
BUG_ON(!(nd->flags & LOOKUP_RCU));
- if (nd->root.mnt) {
+ if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
+ want_root = 1;
spin_lock(&fs->lock);
if (nd->root.mnt != fs->root.mnt ||
nd->root.dentry != fs->root.dentry)
@@ -476,7 +480,7 @@ static int nameidata_dentry_drop_rcu(struct nameidata *nd, struct dentry *dentry
parent->d_count++;
spin_unlock(&dentry->d_lock);
spin_unlock(&parent->d_lock);
- if (nd->root.mnt) {
+ if (want_root) {
path_get(&nd->root);
spin_unlock(&fs->lock);
}
@@ -490,7 +494,7 @@ err:
spin_unlock(&dentry->d_lock);
spin_unlock(&parent->d_lock);
err_root:
- if (nd->root.mnt)
+ if (want_root)
spin_unlock(&fs->lock);
return -ECHILD;
}
@@ -501,7 +505,8 @@ static inline int nameidata_dentry_drop_rcu_maybe(struct nameidata *nd, struct d
if (nd->flags & LOOKUP_RCU) {
if (unlikely(nameidata_dentry_drop_rcu(nd, dentry))) {
nd->flags &= ~LOOKUP_RCU;
- nd->root.mnt = NULL;
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
rcu_read_unlock();
br_read_unlock(vfsmount_lock);
return -ECHILD;
@@ -525,7 +530,8 @@ static int nameidata_drop_rcu_last(struct nameidata *nd)
BUG_ON(!(nd->flags & LOOKUP_RCU));
nd->flags &= ~LOOKUP_RCU;
- nd->root.mnt = NULL;
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
spin_lock(&dentry->d_lock);
if (!__d_rcu_to_refcount(dentry, nd->seq))
goto err_unlock;
@@ -1053,7 +1059,8 @@ static int follow_dotdot_rcu(struct nameidata *nd)
failed:
nd->flags &= ~LOOKUP_RCU;
- nd->root.mnt = NULL;
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
rcu_read_unlock();
br_read_unlock(vfsmount_lock);
return -ECHILD;
@@ -1310,7 +1317,8 @@ static void terminate_walk(struct nameidata *nd)
path_put(&nd->path);
} else {
nd->flags &= ~LOOKUP_RCU;
- nd->root.mnt = NULL;
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
rcu_read_unlock();
br_read_unlock(vfsmount_lock);
}
@@ -1477,6 +1485,25 @@ static int path_init(int dfd, const char *name, unsigned int flags,
nd->last_type = LAST_ROOT; /* if there are only slashes... */
nd->flags = flags | LOOKUP_JUMPED;
nd->depth = 0;
+ if (flags & LOOKUP_ROOT) {
+ struct inode *inode = nd->root.dentry->d_inode;
+ if (!inode->i_op->lookup)
+ return -ENOTDIR;
+ retval = inode_permission(inode, MAY_EXEC);
+ if (retval)
+ return retval;
+ nd->path = nd->root;
+ nd->inode = inode;
+ if (flags & LOOKUP_RCU) {
+ br_read_lock(vfsmount_lock);
+ rcu_read_lock();
+ nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
+ } else {
+ path_get(&nd->path);
+ }
+ return 0;
+ }
+
nd->root.mnt = NULL;
if (*name=='/') {
@@ -1587,7 +1614,7 @@ static int path_lookupat(int dfd, const char *name,
if (base)
fput(base);
- if (nd->root.mnt) {
+ if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
path_put(&nd->root);
nd->root.mnt = NULL;
}
@@ -1638,46 +1665,10 @@ int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
const char *name, unsigned int flags,
struct nameidata *nd)
{
- int result;
-
- /* same as do_path_lookup */
- nd->last_type = LAST_ROOT;
- nd->flags = flags | LOOKUP_JUMPED;
- nd->depth = 0;
-
- nd->path.dentry = dentry;
- nd->path.mnt = mnt;
- path_get(&nd->path);
- nd->root = nd->path;
- path_get(&nd->root);
- nd->inode = nd->path.dentry->d_inode;
-
- current->total_link_count = 0;
-
- result = link_path_walk(name, nd);
- if (!result)
- result = handle_reval_path(nd);
- if (result == -ESTALE) {
- /* nd->path had been dropped */
- current->total_link_count = 0;
- nd->path.dentry = dentry;
- nd->path.mnt = mnt;
- nd->inode = dentry->d_inode;
- path_get(&nd->path);
- nd->flags = flags | LOOKUP_JUMPED | LOOKUP_REVAL;
-
- result = link_path_walk(name, nd);
- if (!result)
- result = handle_reval_path(nd);
- }
- if (unlikely(!result && !audit_dummy_context() && nd->path.dentry &&
- nd->inode))
- audit_inode(name, nd->path.dentry);
-
- path_put(&nd->root);
- nd->root.mnt = NULL;
-
- return result;
+ nd->root.dentry = dentry;
+ nd->root.mnt = mnt;
+ /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */
+ return do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, nd);
}
static struct dentry *__lookup_hash(struct qstr *name,
@@ -2320,7 +2311,7 @@ static struct file *path_openat(int dfd, const char *pathname,
path_put(&link);
}
out:
- if (nd.root.mnt)
+ if (nd.root.mnt && !(nd.flags & LOOKUP_ROOT))
path_put(&nd.root);
if (base)
fput(base);
diff --git a/include/linux/namei.h b/include/linux/namei.h
index 72ffd62..83cd6e5 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -63,6 +63,7 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};
#define LOOKUP_RENAME_TARGET 0x0800
#define LOOKUP_JUMPED 0x1000
+#define LOOKUP_ROOT 0x2000
extern int user_path_at(int, const char __user *, unsigned, struct path *);
generated by cgit v1.1 at 2024-12-25 22:05:31 +0000