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-rw-r--r--fs/namei.c207
1 files changed, 96 insertions, 111 deletions
diff --git a/fs/namei.c b/fs/namei.c
index 5b4eed221530..ad74877e1442 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -37,7 +37,7 @@
#include <linux/hash.h>
#include <linux/bitops.h>
#include <linux/init_task.h>
-#include <asm/uaccess.h>
+#include <linux/uaccess.h>
#include "internal.h"
#include "mount.h"
@@ -1200,7 +1200,7 @@ static int follow_managed(struct path *path, struct nameidata *nd)
if (managed & DCACHE_MANAGE_TRANSIT) {
BUG_ON(!path->dentry->d_op);
BUG_ON(!path->dentry->d_op->d_manage);
- ret = path->dentry->d_op->d_manage(path->dentry, false);
+ ret = path->dentry->d_op->d_manage(path, false);
if (ret < 0)
break;
}
@@ -1263,10 +1263,10 @@ int follow_down_one(struct path *path)
}
EXPORT_SYMBOL(follow_down_one);
-static inline int managed_dentry_rcu(struct dentry *dentry)
+static inline int managed_dentry_rcu(const struct path *path)
{
- return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ?
- dentry->d_op->d_manage(dentry, true) : 0;
+ return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ?
+ path->dentry->d_op->d_manage(path, true) : 0;
}
/*
@@ -1282,7 +1282,7 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
* Don't forget we might have a non-mountpoint managed dentry
* that wants to block transit.
*/
- switch (managed_dentry_rcu(path->dentry)) {
+ switch (managed_dentry_rcu(path)) {
case -ECHILD:
default:
return false;
@@ -1392,8 +1392,7 @@ int follow_down(struct path *path)
if (managed & DCACHE_MANAGE_TRANSIT) {
BUG_ON(!path->dentry->d_op);
BUG_ON(!path->dentry->d_op->d_manage);
- ret = path->dentry->d_op->d_manage(
- path->dentry, false);
+ ret = path->dentry->d_op->d_manage(path, false);
if (ret < 0)
return ret == -EISDIR ? 0 : ret;
}
@@ -1725,30 +1724,35 @@ static int pick_link(struct nameidata *nd, struct path *link,
return 1;
}
+enum {WALK_FOLLOW = 1, WALK_MORE = 2};
+
/*
* Do we need to follow links? We _really_ want to be able
* to do this check without having to look at inode->i_op,
* so we keep a cache of "no, this doesn't need follow_link"
* for the common case.
*/
-static inline int should_follow_link(struct nameidata *nd, struct path *link,
- int follow,
- struct inode *inode, unsigned seq)
+static inline int step_into(struct nameidata *nd, struct path *path,
+ int flags, struct inode *inode, unsigned seq)
{
- if (likely(!d_is_symlink(link->dentry)))
- return 0;
- if (!follow)
+ if (!(flags & WALK_MORE) && nd->depth)
+ put_link(nd);
+ if (likely(!d_is_symlink(path->dentry)) ||
+ !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) {
+ /* not a symlink or should not follow */
+ path_to_nameidata(path, nd);
+ nd->inode = inode;
+ nd->seq = seq;
return 0;
+ }
/* make sure that d_is_symlink above matches inode */
if (nd->flags & LOOKUP_RCU) {
- if (read_seqcount_retry(&link->dentry->d_seq, seq))
+ if (read_seqcount_retry(&path->dentry->d_seq, seq))
return -ECHILD;
}
- return pick_link(nd, link, inode, seq);
+ return pick_link(nd, path, inode, seq);
}
-enum {WALK_GET = 1, WALK_PUT = 2};
-
static int walk_component(struct nameidata *nd, int flags)
{
struct path path;
@@ -1762,7 +1766,7 @@ static int walk_component(struct nameidata *nd, int flags)
*/
if (unlikely(nd->last_type != LAST_NORM)) {
err = handle_dots(nd, nd->last_type);
- if (flags & WALK_PUT)
+ if (!(flags & WALK_MORE) && nd->depth)
put_link(nd);
return err;
}
@@ -1789,15 +1793,7 @@ static int walk_component(struct nameidata *nd, int flags)
inode = d_backing_inode(path.dentry);
}
- if (flags & WALK_PUT)
- put_link(nd);
- err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq);
- if (unlikely(err))
- return err;
- path_to_nameidata(&path, nd);
- nd->inode = inode;
- nd->seq = seq;
- return 0;
+ return step_into(nd, &path, flags, inode, seq);
}
/*
@@ -2104,9 +2100,10 @@ OK:
if (!name)
return 0;
/* last component of nested symlink */
- err = walk_component(nd, WALK_GET | WALK_PUT);
+ err = walk_component(nd, WALK_FOLLOW);
} else {
- err = walk_component(nd, WALK_GET);
+ /* not the last component */
+ err = walk_component(nd, WALK_FOLLOW | WALK_MORE);
}
if (err < 0)
return err;
@@ -2248,12 +2245,7 @@ static inline int lookup_last(struct nameidata *nd)
nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
nd->flags &= ~LOOKUP_PARENT;
- return walk_component(nd,
- nd->flags & LOOKUP_FOLLOW
- ? nd->depth
- ? WALK_PUT | WALK_GET
- : WALK_GET
- : 0);
+ return walk_component(nd, 0);
}
/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
@@ -2558,28 +2550,9 @@ int user_path_at_empty(int dfd, const char __user *name, unsigned flags,
}
EXPORT_SYMBOL(user_path_at_empty);
-/*
- * NB: most callers don't do anything directly with the reference to the
- * to struct filename, but the nd->last pointer points into the name string
- * allocated by getname. So we must hold the reference to it until all
- * path-walking is complete.
- */
-static inline struct filename *
-user_path_parent(int dfd, const char __user *path,
- struct path *parent,
- struct qstr *last,
- int *type,
- unsigned int flags)
-{
- /* only LOOKUP_REVAL is allowed in extra flags */
- return filename_parentat(dfd, getname(path), flags & LOOKUP_REVAL,
- parent, last, type);
-}
-
/**
* mountpoint_last - look up last component for umount
* @nd: pathwalk nameidata - currently pointing at parent directory of "last"
- * @path: pointer to container for result
*
* This is a special lookup_last function just for umount. In this case, we
* need to resolve the path without doing any revalidation.
@@ -2592,23 +2565,20 @@ user_path_parent(int dfd, const char __user *path,
*
* Returns:
* -error: if there was an error during lookup. This includes -ENOENT if the
- * lookup found a negative dentry. The nd->path reference will also be
- * put in this case.
+ * lookup found a negative dentry.
*
- * 0: if we successfully resolved nd->path and found it to not to be a
- * symlink that needs to be followed. "path" will also be populated.
- * The nd->path reference will also be put.
+ * 0: if we successfully resolved nd->last and found it to not to be a
+ * symlink that needs to be followed.
*
* 1: if we successfully resolved nd->last and found it to be a symlink
- * that needs to be followed. "path" will be populated with the path
- * to the link, and nd->path will *not* be put.
+ * that needs to be followed.
*/
static int
-mountpoint_last(struct nameidata *nd, struct path *path)
+mountpoint_last(struct nameidata *nd)
{
int error = 0;
- struct dentry *dentry;
struct dentry *dir = nd->path.dentry;
+ struct path path;
/* If we're in rcuwalk, drop out of it to handle last component */
if (nd->flags & LOOKUP_RCU) {
@@ -2622,37 +2592,28 @@ mountpoint_last(struct nameidata *nd, struct path *path)
error = handle_dots(nd, nd->last_type);
if (error)
return error;
- dentry = dget(nd->path.dentry);
+ path.dentry = dget(nd->path.dentry);
} else {
- dentry = d_lookup(dir, &nd->last);
- if (!dentry) {
+ path.dentry = d_lookup(dir, &nd->last);
+ if (!path.dentry) {
/*
* No cached dentry. Mounted dentries are pinned in the
* cache, so that means that this dentry is probably
* a symlink or the path doesn't actually point
* to a mounted dentry.
*/
- dentry = lookup_slow(&nd->last, dir,
+ path.dentry = lookup_slow(&nd->last, dir,
nd->flags | LOOKUP_NO_REVAL);
- if (IS_ERR(dentry))
- return PTR_ERR(dentry);
+ if (IS_ERR(path.dentry))
+ return PTR_ERR(path.dentry);
}
}
- if (d_is_negative(dentry)) {
- dput(dentry);
+ if (d_is_negative(path.dentry)) {
+ dput(path.dentry);
return -ENOENT;
}
- if (nd->depth)
- put_link(nd);
- path->dentry = dentry;
- path->mnt = nd->path.mnt;
- error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW,
- d_backing_inode(dentry), 0);
- if (unlikely(error))
- return error;
- mntget(path->mnt);
- follow_mount(path);
- return 0;
+ path.mnt = nd->path.mnt;
+ return step_into(nd, &path, 0, d_backing_inode(path.dentry), 0);
}
/**
@@ -2672,13 +2633,19 @@ path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path)
if (IS_ERR(s))
return PTR_ERR(s);
while (!(err = link_path_walk(s, nd)) &&
- (err = mountpoint_last(nd, path)) > 0) {
+ (err = mountpoint_last(nd)) > 0) {
s = trailing_symlink(nd);
if (IS_ERR(s)) {
err = PTR_ERR(s);
break;
}
}
+ if (!err) {
+ *path = nd->path;
+ nd->path.mnt = NULL;
+ nd->path.dentry = NULL;
+ follow_mount(path);
+ }
terminate_walk(nd);
return err;
}
@@ -2895,7 +2862,7 @@ bool may_open_dev(const struct path *path)
!(path->mnt->mnt_sb->s_iflags & SB_I_NODEV);
}
-static int may_open(struct path *path, int acc_mode, int flag)
+static int may_open(const struct path *path, int acc_mode, int flag)
{
struct dentry *dentry = path->dentry;
struct inode *inode = dentry->d_inode;
@@ -2945,7 +2912,7 @@ static int may_open(struct path *path, int acc_mode, int flag)
static int handle_truncate(struct file *filp)
{
- struct path *path = &filp->f_path;
+ const struct path *path = &filp->f_path;
struct inode *inode = path->dentry->d_inode;
int error = get_write_access(inode);
if (error)
@@ -3335,18 +3302,11 @@ static int do_last(struct nameidata *nd,
seq = 0; /* out of RCU mode, so the value doesn't matter */
inode = d_backing_inode(path.dentry);
finish_lookup:
- if (nd->depth)
- put_link(nd);
- error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW,
- inode, seq);
+ error = step_into(nd, &path, 0, inode, seq);
if (unlikely(error))
return error;
-
- path_to_nameidata(&path, nd);
- nd->inode = inode;
- nd->seq = seq;
- /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
finish_open:
+ /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
error = complete_walk(nd);
if (error)
return error;
@@ -3861,8 +3821,8 @@ static long do_rmdir(int dfd, const char __user *pathname)
int type;
unsigned int lookup_flags = 0;
retry:
- name = user_path_parent(dfd, pathname,
- &path, &last, &type, lookup_flags);
+ name = filename_parentat(dfd, getname(pathname), lookup_flags,
+ &path, &last, &type);
if (IS_ERR(name))
return PTR_ERR(name);
@@ -3991,8 +3951,8 @@ static long do_unlinkat(int dfd, const char __user *pathname)
struct inode *delegated_inode = NULL;
unsigned int lookup_flags = 0;
retry:
- name = user_path_parent(dfd, pathname,
- &path, &last, &type, lookup_flags);
+ name = filename_parentat(dfd, getname(pathname), lookup_flags,
+ &path, &last, &type);
if (IS_ERR(name))
return PTR_ERR(name);
@@ -4345,11 +4305,7 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
bool new_is_dir = false;
unsigned max_links = new_dir->i_sb->s_max_links;
- /*
- * Check source == target.
- * On overlayfs need to look at underlying inodes.
- */
- if (d_real_inode(old_dentry) == d_real_inode(new_dentry))
+ if (source == target)
return 0;
error = may_delete(old_dir, old_dentry, is_dir);
@@ -4491,15 +4447,15 @@ SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname,
target_flags = 0;
retry:
- from = user_path_parent(olddfd, oldname,
- &old_path, &old_last, &old_type, lookup_flags);
+ from = filename_parentat(olddfd, getname(oldname), lookup_flags,
+ &old_path, &old_last, &old_type);
if (IS_ERR(from)) {
error = PTR_ERR(from);
goto exit;
}
- to = user_path_parent(newdfd, newname,
- &new_path, &new_last, &new_type, lookup_flags);
+ to = filename_parentat(newdfd, getname(newname), lookup_flags,
+ &new_path, &new_last, &new_type);
if (IS_ERR(to)) {
error = PTR_ERR(to);
goto exit1;
@@ -4650,7 +4606,8 @@ out:
* have ->get_link() not calling nd_jump_link(). Using (or not using) it
* for any given inode is up to filesystem.
*/
-int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
+static int generic_readlink(struct dentry *dentry, char __user *buffer,
+ int buflen)
{
DEFINE_DELAYED_CALL(done);
struct inode *inode = d_inode(dentry);
@@ -4666,7 +4623,36 @@ int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
do_delayed_call(&done);
return res;
}
-EXPORT_SYMBOL(generic_readlink);
+
+/**
+ * vfs_readlink - copy symlink body into userspace buffer
+ * @dentry: dentry on which to get symbolic link
+ * @buffer: user memory pointer
+ * @buflen: size of buffer
+ *
+ * Does not touch atime. That's up to the caller if necessary
+ *
+ * Does not call security hook.
+ */
+int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen)
+{
+ struct inode *inode = d_inode(dentry);
+
+ if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) {
+ if (unlikely(inode->i_op->readlink))
+ return inode->i_op->readlink(dentry, buffer, buflen);
+
+ if (!d_is_symlink(dentry))
+ return -EINVAL;
+
+ spin_lock(&inode->i_lock);
+ inode->i_opflags |= IOP_DEFAULT_READLINK;
+ spin_unlock(&inode->i_lock);
+ }
+
+ return generic_readlink(dentry, buffer, buflen);
+}
+EXPORT_SYMBOL(vfs_readlink);
/**
* vfs_get_link - get symlink body
@@ -4783,7 +4769,6 @@ int page_symlink(struct inode *inode, const char *symname, int len)
EXPORT_SYMBOL(page_symlink);
const struct inode_operations page_symlink_inode_operations = {
- .readlink = generic_readlink,
.get_link = page_get_link,
};
EXPORT_SYMBOL(page_symlink_inode_operations);
generated by cgit v1.2.3 (git 2.39.0) at 2024-12-14 20:37:30 +0300