}
/**
- * inode_permission - check for access rights to a given inode
- * @inode: inode to check permission on
- * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...)
+ * __inode_permission - Check for access rights to a given inode
+ * @inode: Inode to check permission on
+ * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
*
- * Used to check for read/write/execute permissions on an inode.
- * We use "fsuid" for this, letting us set arbitrary permissions
- * for filesystem access without changing the "normal" uids which
- * are used for other things.
+ * Check for read/write/execute permissions on an inode.
*
* When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
+ *
+ * This does not check for a read-only file system. You probably want
+ * inode_permission().
*/
-int inode_permission(struct inode *inode, int mask)
+int __inode_permission(struct inode *inode, int mask)
{
int retval;
if (unlikely(mask & MAY_WRITE)) {
- umode_t mode = inode->i_mode;
-
- /*
- * Nobody gets write access to a read-only fs.
- */
- if (IS_RDONLY(inode) &&
- (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
- return -EROFS;
-
/*
* Nobody gets write access to an immutable file.
*/
return security_inode_permission(inode, mask);
}
+/**
+ * sb_permission - Check superblock-level permissions
+ * @sb: Superblock of inode to check permission on
+ * @inode: Inode to check permission on
+ * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
+ *
+ * Separate out file-system wide checks from inode-specific permission checks.
+ */
+static int sb_permission(struct super_block *sb, struct inode *inode, int mask)
+{
+ if (unlikely(mask & MAY_WRITE)) {
+ umode_t mode = inode->i_mode;
+
+ /* Nobody gets write access to a read-only fs. */
+ if ((sb->s_flags & MS_RDONLY) &&
+ (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
+ return -EROFS;
+ }
+ return 0;
+}
+
+/**
+ * inode_permission - Check for access rights to a given inode
+ * @inode: Inode to check permission on
+ * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
+ *
+ * Check for read/write/execute permissions on an inode. We use fs[ug]id for
+ * this, letting us set arbitrary permissions for filesystem access without
+ * changing the "normal" UIDs which are used for other things.
+ *
+ * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
+ */
+int inode_permission(struct inode *inode, int mask)
+{
+ int retval;
+
+ retval = sb_permission(inode->i_sb, inode, mask);
+ if (retval)
+ return retval;
+ return __inode_permission(inode, mask);
+}
+
/**
* path_get - get a reference to a path
* @path: path to get the reference to
* to restart the path walk from the beginning in ref-walk mode.
*/
+static inline void lock_rcu_walk(void)
+{
+ br_read_lock(&vfsmount_lock);
+ rcu_read_lock();
+}
+
+static inline void unlock_rcu_walk(void)
+{
+ rcu_read_unlock();
+ br_read_unlock(&vfsmount_lock);
+}
+
/**
* unlazy_walk - try to switch to ref-walk mode.
* @nd: nameidata pathwalk data
}
mntget(nd->path.mnt);
- rcu_read_unlock();
- br_read_unlock(&vfsmount_lock);
+ unlock_rcu_walk();
nd->flags &= ~LOOKUP_RCU;
return 0;
return -ECHILD;
}
-/**
- * release_open_intent - free up open intent resources
- * @nd: pointer to nameidata
- */
-void release_open_intent(struct nameidata *nd)
-{
- struct file *file = nd->intent.open.file;
-
- if (file && !IS_ERR(file)) {
- if (file->f_path.dentry == NULL)
- put_filp(file);
- else
- fput(file);
- }
-}
-
-static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd)
+static inline int d_revalidate(struct dentry *dentry, unsigned int flags)
{
- return dentry->d_op->d_revalidate(dentry, nd);
+ return dentry->d_op->d_revalidate(dentry, flags);
}
/**
spin_lock(&dentry->d_lock);
if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) {
spin_unlock(&dentry->d_lock);
- rcu_read_unlock();
- br_read_unlock(&vfsmount_lock);
+ unlock_rcu_walk();
return -ECHILD;
}
BUG_ON(nd->inode != dentry->d_inode);
spin_unlock(&dentry->d_lock);
mntget(nd->path.mnt);
- rcu_read_unlock();
- br_read_unlock(&vfsmount_lock);
+ unlock_rcu_walk();
}
if (likely(!(nd->flags & LOOKUP_JUMPED)))
return 0;
/* Note: we do not d_invalidate() */
- status = d_revalidate(dentry, nd);
+ status = d_revalidate(dentry, nd->flags);
if (status > 0)
return 0;
nd->path.dentry = path->dentry;
}
+/*
+ * Helper to directly jump to a known parsed path from ->follow_link,
+ * caller must have taken a reference to path beforehand.
+ */
+void nd_jump_link(struct nameidata *nd, struct path *path)
+{
+ path_put(&nd->path);
+
+ nd->path = *path;
+ nd->inode = nd->path.dentry->d_inode;
+ nd->flags |= LOOKUP_JUMPED;
+
+ BUG_ON(nd->inode->i_op->follow_link);
+}
+
static inline void put_link(struct nameidata *nd, struct path *link, void *cookie)
{
struct inode *inode = link->dentry->d_inode;
- if (!IS_ERR(cookie) && inode->i_op->put_link)
+ if (inode->i_op->put_link)
inode->i_op->put_link(link->dentry, nd, cookie);
path_put(link);
}
+int sysctl_protected_symlinks __read_mostly = 1;
+int sysctl_protected_hardlinks __read_mostly = 1;
+
+/**
+ * may_follow_link - Check symlink following for unsafe situations
+ * @link: The path of the symlink
+ * @nd: nameidata pathwalk data
+ *
+ * In the case of the sysctl_protected_symlinks sysctl being enabled,
+ * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is
+ * in a sticky world-writable directory. This is to protect privileged
+ * processes from failing races against path names that may change out
+ * from under them by way of other users creating malicious symlinks.
+ * It will permit symlinks to be followed only when outside a sticky
+ * world-writable directory, or when the uid of the symlink and follower
+ * match, or when the directory owner matches the symlink's owner.
+ *
+ * Returns 0 if following the symlink is allowed, -ve on error.
+ */
+static inline int may_follow_link(struct path *link, struct nameidata *nd)
+{
+ const struct inode *inode;
+ const struct inode *parent;
+
+ if (!sysctl_protected_symlinks)
+ return 0;
+
+ /* Allowed if owner and follower match. */
+ inode = link->dentry->d_inode;
+ if (current_cred()->fsuid == inode->i_uid)
+ return 0;
+
+ /* Allowed if parent directory not sticky and world-writable. */
+ parent = nd->path.dentry->d_inode;
+ if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH))
+ return 0;
+
+ /* Allowed if parent directory and link owner match. */
+ if (parent->i_uid == inode->i_uid)
+ return 0;
+
+ path_put_conditional(link, nd);
+ path_put(&nd->path);
+ audit_log_link_denied("follow_link", link);
+ return -EACCES;
+}
+
+/**
+ * safe_hardlink_source - Check for safe hardlink conditions
+ * @inode: the source inode to hardlink from
+ *
+ * Return false if at least one of the following conditions:
+ * - inode is not a regular file
+ * - inode is setuid
+ * - inode is setgid and group-exec
+ * - access failure for read and write
+ *
+ * Otherwise returns true.
+ */
+static bool safe_hardlink_source(struct inode *inode)
+{
+ umode_t mode = inode->i_mode;
+
+ /* Special files should not get pinned to the filesystem. */
+ if (!S_ISREG(mode))
+ return false;
+
+ /* Setuid files should not get pinned to the filesystem. */
+ if (mode & S_ISUID)
+ return false;
+
+ /* Executable setgid files should not get pinned to the filesystem. */
+ if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
+ return false;
+
+ /* Hardlinking to unreadable or unwritable sources is dangerous. */
+ if (inode_permission(inode, MAY_READ | MAY_WRITE))
+ return false;
+
+ return true;
+}
+
+/**
+ * may_linkat - Check permissions for creating a hardlink
+ * @link: the source to hardlink from
+ *
+ * Block hardlink when all of:
+ * - sysctl_protected_hardlinks enabled
+ * - fsuid does not match inode
+ * - hardlink source is unsafe (see safe_hardlink_source() above)
+ * - not CAP_FOWNER
+ *
+ * Returns 0 if successful, -ve on error.
+ */
+static int may_linkat(struct path *link)
+{
+ const struct cred *cred;
+ struct inode *inode;
+
+ if (!sysctl_protected_hardlinks)
+ return 0;
+
+ cred = current_cred();
+ inode = link->dentry->d_inode;
+
+ /* Source inode owner (or CAP_FOWNER) can hardlink all they like,
+ * otherwise, it must be a safe source.
+ */
+ if (cred->fsuid == inode->i_uid || safe_hardlink_source(inode) ||
+ capable(CAP_FOWNER))
+ return 0;
+
+ audit_log_link_denied("linkat", link);
+ return -EPERM;
+}
+
static __always_inline int
follow_link(struct path *link, struct nameidata *nd, void **p)
{
- int error;
struct dentry *dentry = link->dentry;
+ int error;
+ char *s;
BUG_ON(nd->flags & LOOKUP_RCU);
if (link->mnt == nd->path.mnt)
mntget(link->mnt);
- if (unlikely(current->total_link_count >= 40)) {
- *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */
- path_put(&nd->path);
- return -ELOOP;
- }
+ error = -ELOOP;
+ if (unlikely(current->total_link_count >= 40))
+ goto out_put_nd_path;
+
cond_resched();
current->total_link_count++;
nd_set_link(nd, NULL);
error = security_inode_follow_link(link->dentry, nd);
- if (error) {
- *p = ERR_PTR(error); /* no ->put_link(), please */
- path_put(&nd->path);
- return error;
- }
+ if (error)
+ goto out_put_nd_path;
nd->last_type = LAST_BIND;
*p = dentry->d_inode->i_op->follow_link(dentry, nd);
error = PTR_ERR(*p);
- if (!IS_ERR(*p)) {
- char *s = nd_get_link(nd);
- error = 0;
- if (s)
- error = __vfs_follow_link(nd, s);
- else if (nd->last_type == LAST_BIND) {
- nd->flags |= LOOKUP_JUMPED;
- nd->inode = nd->path.dentry->d_inode;
- if (nd->inode->i_op->follow_link) {
- /* stepped on a _really_ weird one */
- path_put(&nd->path);
- error = -ELOOP;
- }
- }
+ if (IS_ERR(*p))
+ goto out_put_nd_path;
+
+ error = 0;
+ s = nd_get_link(nd);
+ if (s) {
+ error = __vfs_follow_link(nd, s);
+ if (unlikely(error))
+ put_link(nd, link, *p);
}
+
+ return error;
+
+out_put_nd_path:
+ path_put(&nd->path);
+ path_put(link);
return error;
}
return 1;
}
+/*
+ * follow_up - Find the mountpoint of path's vfsmount
+ *
+ * Given a path, find the mountpoint of its source file system.
+ * Replace @path with the path of the mountpoint in the parent mount.
+ * Up is towards /.
+ *
+ * Return 1 if we went up a level and 0 if we were already at the
+ * root.
+ */
int follow_up(struct path *path)
{
struct mount *mnt = real_mount(path->mnt);
br_read_lock(&vfsmount_lock);
parent = mnt->mnt_parent;
- if (&parent->mnt == path->mnt) {
+ if (parent == mnt) {
br_read_unlock(&vfsmount_lock);
return 0;
}
nd->flags &= ~LOOKUP_RCU;
if (!(nd->flags & LOOKUP_ROOT))
nd->root.mnt = NULL;
- rcu_read_unlock();
- br_read_unlock(&vfsmount_lock);
+ unlock_rcu_walk();
return -ECHILD;
}
* dir->d_inode->i_mutex must be held
*/
static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir,
- struct nameidata *nd, bool *need_lookup)
+ unsigned int flags, bool *need_lookup)
{
struct dentry *dentry;
int error;
if (d_need_lookup(dentry)) {
*need_lookup = true;
} else if (dentry->d_flags & DCACHE_OP_REVALIDATE) {
- error = d_revalidate(dentry, nd);
+ error = d_revalidate(dentry, flags);
if (unlikely(error <= 0)) {
if (error < 0) {
dput(dentry);
* dir->d_inode->i_mutex must be held
*/
static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry,
- struct nameidata *nd)
+ unsigned int flags)
{
struct dentry *old;
return ERR_PTR(-ENOENT);
}
- old = dir->i_op->lookup(dir, dentry, nd);
+ old = dir->i_op->lookup(dir, dentry, flags);
if (unlikely(old)) {
dput(dentry);
dentry = old;
}
static struct dentry *__lookup_hash(struct qstr *name,
- struct dentry *base, struct nameidata *nd)
+ struct dentry *base, unsigned int flags)
{
bool need_lookup;
struct dentry *dentry;
- dentry = lookup_dcache(name, base, nd, &need_lookup);
+ dentry = lookup_dcache(name, base, flags, &need_lookup);
if (!need_lookup)
return dentry;
- return lookup_real(base->d_inode, dentry, nd);
+ return lookup_real(base->d_inode, dentry, flags);
}
/*
if (unlikely(d_need_lookup(dentry)))
goto unlazy;
if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
- status = d_revalidate(dentry, nd);
+ status = d_revalidate(dentry, nd->flags);
if (unlikely(status <= 0)) {
if (status != -ECHILD)
need_reval = 0;
}
if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval)
- status = d_revalidate(dentry, nd);
+ status = d_revalidate(dentry, nd->flags);
if (unlikely(status <= 0)) {
if (status < 0) {
dput(dentry);
BUG_ON(nd->inode != parent->d_inode);
mutex_lock(&parent->d_inode->i_mutex);
- dentry = __lookup_hash(name, parent, nd);
+ dentry = __lookup_hash(name, parent, nd->flags);
mutex_unlock(&parent->d_inode->i_mutex);
if (IS_ERR(dentry))
return PTR_ERR(dentry);
nd->flags &= ~LOOKUP_RCU;
if (!(nd->flags & LOOKUP_ROOT))
nd->root.mnt = NULL;
- rcu_read_unlock();
- br_read_unlock(&vfsmount_lock);
+ unlock_rcu_walk();
}
}
void *cookie;
res = follow_link(&link, nd, &cookie);
- if (!res)
- res = walk_component(nd, path, &nd->last,
- nd->last_type, LOOKUP_FOLLOW);
+ if (res)
+ break;
+ res = walk_component(nd, path, &nd->last,
+ nd->last_type, LOOKUP_FOLLOW);
put_link(nd, &link, cookie);
} while (res > 0);
nd->path = nd->root;
nd->inode = inode;
if (flags & LOOKUP_RCU) {
- br_read_lock(&vfsmount_lock);
- rcu_read_lock();
+ lock_rcu_walk();
nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
} else {
path_get(&nd->path);
if (*name=='/') {
if (flags & LOOKUP_RCU) {
- br_read_lock(&vfsmount_lock);
- rcu_read_lock();
+ lock_rcu_walk();
set_root_rcu(nd);
} else {
set_root(nd);
struct fs_struct *fs = current->fs;
unsigned seq;
- br_read_lock(&vfsmount_lock);
- rcu_read_lock();
+ lock_rcu_walk();
do {
seq = read_seqcount_begin(&fs->seq);
if (fput_needed)
*fp = file;
nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
- br_read_lock(&vfsmount_lock);
- rcu_read_lock();
+ lock_rcu_walk();
} else {
path_get(&file->f_path);
fput_light(file, fput_needed);
while (err > 0) {
void *cookie;
struct path link = path;
+ err = may_follow_link(&link, nd);
+ if (unlikely(err))
+ break;
nd->flags |= LOOKUP_PARENT;
err = follow_link(&link, nd, &cookie);
- if (!err)
- err = lookup_last(nd, &path);
+ if (err)
+ break;
+ err = lookup_last(nd, &path);
put_link(nd, &link, cookie);
}
}
return retval;
}
-int kern_path_parent(const char *name, struct nameidata *nd)
+/* does lookup, returns the object with parent locked */
+struct dentry *kern_path_locked(const char *name, struct path *path)
{
- return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd);
+ struct nameidata nd;
+ struct dentry *d;
+ int err = do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, &nd);
+ if (err)
+ return ERR_PTR(err);
+ if (nd.last_type != LAST_NORM) {
+ path_put(&nd.path);
+ return ERR_PTR(-EINVAL);
+ }
+ mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
+ d = __lookup_hash(&nd.last, nd.path.dentry, 0);
+ if (IS_ERR(d)) {
+ mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
+ path_put(&nd.path);
+ return d;
+ }
+ *path = nd.path;
+ return d;
}
int kern_path(const char *name, unsigned int flags, struct path *path)
*/
static struct dentry *lookup_hash(struct nameidata *nd)
{
- return __lookup_hash(&nd->last, nd->path.dentry, nd);
+ return __lookup_hash(&nd->last, nd->path.dentry, nd->flags);
}
/**
if (err)
return ERR_PTR(err);
- return __lookup_hash(&this, base, NULL);
+ return __lookup_hash(&this, base, 0);
}
int user_path_at_empty(int dfd, const char __user *name, unsigned flags,
}
int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
- struct nameidata *nd)
+ bool want_excl)
{
int error = may_create(dir, dentry);
-
if (error)
return error;
error = security_inode_create(dir, dentry, mode);
if (error)
return error;
- error = dir->i_op->create(dir, dentry, mode, nd);
+ error = dir->i_op->create(dir, dentry, mode, want_excl);
if (!error)
fsnotify_create(dir, dentry);
return error;
return flag;
}
+static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode)
+{
+ int error = security_path_mknod(dir, dentry, mode, 0);
+ if (error)
+ return error;
+
+ error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC);
+ if (error)
+ return error;
+
+ return security_inode_create(dir->dentry->d_inode, dentry, mode);
+}
+
/*
- * Handle the last step of open()
+ * Attempt to atomically look up, create and open a file from a negative
+ * dentry.
+ *
+ * Returns 0 if successful. The file will have been created and attached to
+ * @file by the filesystem calling finish_open().
+ *
+ * Returns 1 if the file was looked up only or didn't need creating. The
+ * caller will need to perform the open themselves. @path will have been
+ * updated to point to the new dentry. This may be negative.
+ *
+ * Returns an error code otherwise.
+ */
+static int atomic_open(struct nameidata *nd, struct dentry *dentry,
+ struct path *path, struct file *file,
+ const struct open_flags *op,
+ bool got_write, bool need_lookup,
+ int *opened)
+{
+ struct inode *dir = nd->path.dentry->d_inode;
+ unsigned open_flag = open_to_namei_flags(op->open_flag);
+ umode_t mode;
+ int error;
+ int acc_mode;
+ int create_error = 0;
+ struct dentry *const DENTRY_NOT_SET = (void *) -1UL;
+
+ BUG_ON(dentry->d_inode);
+
+ /* Don't create child dentry for a dead directory. */
+ if (unlikely(IS_DEADDIR(dir))) {
+ error = -ENOENT;
+ goto out;
+ }
+
+ mode = op->mode;
+ if ((open_flag & O_CREAT) && !IS_POSIXACL(dir))
+ mode &= ~current_umask();
+
+ if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) {
+ open_flag &= ~O_TRUNC;
+ *opened |= FILE_CREATED;
+ }
+
+ /*
+ * Checking write permission is tricky, bacuse we don't know if we are
+ * going to actually need it: O_CREAT opens should work as long as the
+ * file exists. But checking existence breaks atomicity. The trick is
+ * to check access and if not granted clear O_CREAT from the flags.
+ *
+ * Another problem is returing the "right" error value (e.g. for an
+ * O_EXCL open we want to return EEXIST not EROFS).
+ */
+ if (((open_flag & (O_CREAT | O_TRUNC)) ||
+ (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) {
+ if (!(open_flag & O_CREAT)) {
+ /*
+ * No O_CREATE -> atomicity not a requirement -> fall
+ * back to lookup + open
+ */
+ goto no_open;
+ } else if (open_flag & (O_EXCL | O_TRUNC)) {
+ /* Fall back and fail with the right error */
+ create_error = -EROFS;
+ goto no_open;
+ } else {
+ /* No side effects, safe to clear O_CREAT */
+ create_error = -EROFS;
+ open_flag &= ~O_CREAT;
+ }
+ }
+
+ if (open_flag & O_CREAT) {
+ error = may_o_create(&nd->path, dentry, mode);
+ if (error) {
+ create_error = error;
+ if (open_flag & O_EXCL)
+ goto no_open;
+ open_flag &= ~O_CREAT;
+ }
+ }
+
+ if (nd->flags & LOOKUP_DIRECTORY)
+ open_flag |= O_DIRECTORY;
+
+ file->f_path.dentry = DENTRY_NOT_SET;
+ file->f_path.mnt = nd->path.mnt;
+ error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode,
+ opened);
+ if (error < 0) {
+ if (create_error && error == -ENOENT)
+ error = create_error;
+ goto out;
+ }
+
+ acc_mode = op->acc_mode;
+ if (*opened & FILE_CREATED) {
+ fsnotify_create(dir, dentry);
+ acc_mode = MAY_OPEN;
+ }
+
+ if (error) { /* returned 1, that is */
+ if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) {
+ error = -EIO;
+ goto out;
+ }
+ if (file->f_path.dentry) {
+ dput(dentry);
+ dentry = file->f_path.dentry;
+ }
+ if (create_error && dentry->d_inode == NULL) {
+ error = create_error;
+ goto out;
+ }
+ goto looked_up;
+ }
+
+ /*
+ * We didn't have the inode before the open, so check open permission
+ * here.
+ */
+ error = may_open(&file->f_path, acc_mode, open_flag);
+ if (error)
+ fput(file);
+
+out:
+ dput(dentry);
+ return error;
+
+no_open:
+ if (need_lookup) {
+ dentry = lookup_real(dir, dentry, nd->flags);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+
+ if (create_error) {
+ int open_flag = op->open_flag;
+
+ error = create_error;
+ if ((open_flag & O_EXCL)) {
+ if (!dentry->d_inode)
+ goto out;
+ } else if (!dentry->d_inode) {
+ goto out;
+ } else if ((open_flag & O_TRUNC) &&
+ S_ISREG(dentry->d_inode->i_mode)) {
+ goto out;
+ }
+ /* will fail later, go on to get the right error */
+ }
+ }
+looked_up:
+ path->dentry = dentry;
+ path->mnt = nd->path.mnt;
+ return 1;
+}
+
+/*
+ * Look up and maybe create and open the last component.
+ *
+ * Must be called with i_mutex held on parent.
+ *
+ * Returns 0 if the file was successfully atomically created (if necessary) and
+ * opened. In this case the file will be returned attached to @file.
+ *
+ * Returns 1 if the file was not completely opened at this time, though lookups
+ * and creations will have been performed and the dentry returned in @path will
+ * be positive upon return if O_CREAT was specified. If O_CREAT wasn't
+ * specified then a negative dentry may be returned.
+ *
+ * An error code is returned otherwise.
+ *
+ * FILE_CREATE will be set in @*opened if the dentry was created and will be
+ * cleared otherwise prior to returning.
*/
-static struct file *do_last(struct nameidata *nd, struct path *path,
- const struct open_flags *op, const char *pathname)
+static int lookup_open(struct nameidata *nd, struct path *path,
+ struct file *file,
+ const struct open_flags *op,
+ bool got_write, int *opened)
{
struct dentry *dir = nd->path.dentry;
+ struct inode *dir_inode = dir->d_inode;
struct dentry *dentry;
+ int error;
+ bool need_lookup;
+
+ *opened &= ~FILE_CREATED;
+ dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+
+ /* Cached positive dentry: will open in f_op->open */
+ if (!need_lookup && dentry->d_inode)
+ goto out_no_open;
+
+ if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) {
+ return atomic_open(nd, dentry, path, file, op, got_write,
+ need_lookup, opened);
+ }
+
+ if (need_lookup) {
+ BUG_ON(dentry->d_inode);
+
+ dentry = lookup_real(dir_inode, dentry, nd->flags);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+ }
+
+ /* Negative dentry, just create the file */
+ if (!dentry->d_inode && (op->open_flag & O_CREAT)) {
+ umode_t mode = op->mode;
+ if (!IS_POSIXACL(dir->d_inode))
+ mode &= ~current_umask();
+ /*
+ * This write is needed to ensure that a
+ * rw->ro transition does not occur between
+ * the time when the file is created and when
+ * a permanent write count is taken through
+ * the 'struct file' in finish_open().
+ */
+ if (!got_write) {
+ error = -EROFS;
+ goto out_dput;
+ }
+ *opened |= FILE_CREATED;
+ error = security_path_mknod(&nd->path, dentry, mode, 0);
+ if (error)
+ goto out_dput;
+ error = vfs_create(dir->d_inode, dentry, mode,
+ nd->flags & LOOKUP_EXCL);
+ if (error)
+ goto out_dput;
+ }
+out_no_open:
+ path->dentry = dentry;
+ path->mnt = nd->path.mnt;
+ return 1;
+
+out_dput:
+ dput(dentry);
+ return error;
+}
+
+/*
+ * Handle the last step of open()
+ */
+static int do_last(struct nameidata *nd, struct path *path,
+ struct file *file, const struct open_flags *op,
+ int *opened, const char *pathname)
+{
+ struct dentry *dir = nd->path.dentry;
int open_flag = op->open_flag;
- int will_truncate = open_flag & O_TRUNC;
- int want_write = 0;
+ bool will_truncate = (open_flag & O_TRUNC) != 0;
+ bool got_write = false;
int acc_mode = op->acc_mode;
- struct file *filp;
struct inode *inode;
- int symlink_ok = 0;
+ bool symlink_ok = false;
struct path save_parent = { .dentry = NULL, .mnt = NULL };
bool retried = false;
int error;
case LAST_DOT:
error = handle_dots(nd, nd->last_type);
if (error)
- return ERR_PTR(error);
+ return error;
/* fallthrough */
case LAST_ROOT:
error = complete_walk(nd);
if (error)
- return ERR_PTR(error);
+ return error;
audit_inode(pathname, nd->path.dentry);
if (open_flag & O_CREAT) {
error = -EISDIR;
- goto exit;
+ goto out;
}
- goto ok;
+ goto finish_open;
case LAST_BIND:
error = complete_walk(nd);
if (error)
- return ERR_PTR(error);
+ return error;
audit_inode(pathname, dir);
- goto ok;
+ goto finish_open;
}
if (!(open_flag & O_CREAT)) {
if (nd->last.name[nd->last.len])
nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW))
- symlink_ok = 1;
+ symlink_ok = true;
/* we _can_ be in RCU mode here */
error = lookup_fast(nd, &nd->last, path, &inode);
- if (unlikely(error)) {
- if (error < 0)
- goto exit;
+ if (likely(!error))
+ goto finish_lookup;
- error = lookup_slow(nd, &nd->last, path);
- if (error < 0)
- goto exit;
+ if (error < 0)
+ goto out;
- inode = path->dentry->d_inode;
- }
- goto finish_lookup;
- }
-
- /* create side of things */
- /*
- * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED has been
- * cleared when we got to the last component we are about to look up
- */
- error = complete_walk(nd);
- if (error)
- return ERR_PTR(error);
+ BUG_ON(nd->inode != dir->d_inode);
+ } else {
+ /* create side of things */
+ /*
+ * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED
+ * has been cleared when we got to the last component we are
+ * about to look up
+ */
+ error = complete_walk(nd);
+ if (error)
+ return error;
- audit_inode(pathname, dir);
- error = -EISDIR;
- /* trailing slashes? */
- if (nd->last.name[nd->last.len])
- goto exit;
+ audit_inode(pathname, dir);
+ error = -EISDIR;
+ /* trailing slashes? */
+ if (nd->last.name[nd->last.len])
+ goto out;
+ }
retry_lookup:
+ if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) {
+ error = mnt_want_write(nd->path.mnt);
+ if (!error)
+ got_write = true;
+ /*
+ * do _not_ fail yet - we might not need that or fail with
+ * a different error; let lookup_open() decide; we'll be
+ * dropping this one anyway.
+ */
+ }
mutex_lock(&dir->d_inode->i_mutex);
+ error = lookup_open(nd, path, file, op, got_write, opened);
+ mutex_unlock(&dir->d_inode->i_mutex);
- dentry = lookup_hash(nd);
- error = PTR_ERR(dentry);
- if (IS_ERR(dentry)) {
- mutex_unlock(&dir->d_inode->i_mutex);
- goto exit;
- }
+ if (error <= 0) {
+ if (error)
+ goto out;
- path->dentry = dentry;
- path->mnt = nd->path.mnt;
+ if ((*opened & FILE_CREATED) ||
+ !S_ISREG(file->f_path.dentry->d_inode->i_mode))
+ will_truncate = false;
- /* Negative dentry, just create the file */
- if (!dentry->d_inode) {
- umode_t mode = op->mode;
- if (!IS_POSIXACL(dir->d_inode))
- mode &= ~current_umask();
- /*
- * This write is needed to ensure that a
- * rw->ro transition does not occur between
- * the time when the file is created and when
- * a permanent write count is taken through
- * the 'struct file' in nameidata_to_filp().
- */
- error = mnt_want_write(nd->path.mnt);
- if (error)
- goto exit_mutex_unlock;
- want_write = 1;
+ audit_inode(pathname, file->f_path.dentry);
+ goto opened;
+ }
+
+ if (*opened & FILE_CREATED) {
/* Don't check for write permission, don't truncate */
open_flag &= ~O_TRUNC;
- will_truncate = 0;
+ will_truncate = false;
acc_mode = MAY_OPEN;
- error = security_path_mknod(&nd->path, dentry, mode, 0);
- if (error)
- goto exit_mutex_unlock;
- error = vfs_create(dir->d_inode, dentry, mode, nd);
- if (error)
- goto exit_mutex_unlock;
- mutex_unlock(&dir->d_inode->i_mutex);
- dput(nd->path.dentry);
- nd->path.dentry = dentry;
- goto common;
+ path_to_nameidata(path, nd);
+ goto finish_open_created;
}
/*
- * It already exists.
+ * create/update audit record if it already exists.
*/
- mutex_unlock(&dir->d_inode->i_mutex);
- audit_inode(pathname, path->dentry);
+ if (path->dentry->d_inode)
+ audit_inode(pathname, path->dentry);
+
+ /*
+ * If atomic_open() acquired write access it is dropped now due to
+ * possible mount and symlink following (this might be optimized away if
+ * necessary...)
+ */
+ if (got_write) {
+ mnt_drop_write(nd->path.mnt);
+ got_write = false;
+ }
error = -EEXIST;
- if (open_flag & O_EXCL)
+ if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))
goto exit_dput;
error = follow_managed(path, nd->flags);
error = -ENOENT;
if (!inode) {
path_to_nameidata(path, nd);
- goto exit;
+ goto out;
}
if (should_follow_link(inode, !symlink_ok)) {
if (nd->flags & LOOKUP_RCU) {
if (unlikely(unlazy_walk(nd, path->dentry))) {
error = -ECHILD;
- goto exit;
+ goto out;
}
}
BUG_ON(inode != path->dentry->d_inode);
- return NULL;
+ return 1;
}
if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) {
error = complete_walk(nd);
if (error) {
path_put(&save_parent);
- return ERR_PTR(error);
+ return error;
}
error = -EISDIR;
if ((open_flag & O_CREAT) && S_ISDIR(nd->inode->i_mode))
- goto exit;
+ goto out;
error = -ENOTDIR;
if ((nd->flags & LOOKUP_DIRECTORY) && !nd->inode->i_op->lookup)
- goto exit;
+ goto out;
audit_inode(pathname, nd->path.dentry);
-ok:
+finish_open:
if (!S_ISREG(nd->inode->i_mode))
- will_truncate = 0;
+ will_truncate = false;
if (will_truncate) {
error = mnt_want_write(nd->path.mnt);
if (error)
- goto exit;
- want_write = 1;
+ goto out;
+ got_write = true;
}
-common:
+finish_open_created:
error = may_open(&nd->path, acc_mode, open_flag);
if (error)
- goto exit;
- filp = nameidata_to_filp(nd);
- if (filp == ERR_PTR(-EOPENSTALE) && save_parent.dentry && !retried) {
- BUG_ON(save_parent.dentry != dir);
- path_put(&nd->path);
- nd->path = save_parent;
- nd->inode = dir->d_inode;
- save_parent.mnt = NULL;
- save_parent.dentry = NULL;
- if (want_write) {
- mnt_drop_write(nd->path.mnt);
- want_write = 0;
- }
- retried = true;
- goto retry_lookup;
- }
- if (!IS_ERR(filp)) {
- error = ima_file_check(filp, op->acc_mode);
- if (error) {
- fput(filp);
- filp = ERR_PTR(error);
- }
+ goto out;
+ file->f_path.mnt = nd->path.mnt;
+ error = finish_open(file, nd->path.dentry, NULL, opened);
+ if (error) {
+ if (error == -EOPENSTALE)
+ goto stale_open;
+ goto out;
}
- if (!IS_ERR(filp)) {
- if (will_truncate) {
- error = handle_truncate(filp);
- if (error) {
- fput(filp);
- filp = ERR_PTR(error);
- }
- }
+opened:
+ error = open_check_o_direct(file);
+ if (error)
+ goto exit_fput;
+ error = ima_file_check(file, op->acc_mode);
+ if (error)
+ goto exit_fput;
+
+ if (will_truncate) {
+ error = handle_truncate(file);
+ if (error)
+ goto exit_fput;
}
out:
- if (want_write)
+ if (got_write)
mnt_drop_write(nd->path.mnt);
path_put(&save_parent);
terminate_walk(nd);
- return filp;
+ return error;
-exit_mutex_unlock:
- mutex_unlock(&dir->d_inode->i_mutex);
exit_dput:
path_put_conditional(path, nd);
-exit:
- filp = ERR_PTR(error);
goto out;
+exit_fput:
+ fput(file);
+ goto out;
+
+stale_open:
+ /* If no saved parent or already retried then can't retry */
+ if (!save_parent.dentry || retried)
+ goto out;
+
+ BUG_ON(save_parent.dentry != dir);
+ path_put(&nd->path);
+ nd->path = save_parent;
+ nd->inode = dir->d_inode;
+ save_parent.mnt = NULL;
+ save_parent.dentry = NULL;
+ if (got_write) {
+ mnt_drop_write(nd->path.mnt);
+ got_write = false;
+ }
+ retried = true;
+ goto retry_lookup;
}
static struct file *path_openat(int dfd, const char *pathname,
struct nameidata *nd, const struct open_flags *op, int flags)
{
struct file *base = NULL;
- struct file *filp;
+ struct file *file;
struct path path;
+ int opened = 0;
int error;
- filp = get_empty_filp();
- if (!filp)
+ file = get_empty_filp();
+ if (!file)
return ERR_PTR(-ENFILE);
- filp->f_flags = op->open_flag;
- nd->intent.open.file = filp;
- nd->intent.open.flags = open_to_namei_flags(op->open_flag);
- nd->intent.open.create_mode = op->mode;
+ file->f_flags = op->open_flag;
error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base);
if (unlikely(error))
- goto out_filp;
+ goto out;
current->total_link_count = 0;
error = link_path_walk(pathname, nd);
if (unlikely(error))
- goto out_filp;
+ goto out;
- filp = do_last(nd, &path, op, pathname);
- while (unlikely(!filp)) { /* trailing symlink */
+ error = do_last(nd, &path, file, op, &opened, pathname);
+ while (unlikely(error > 0)) { /* trailing symlink */
struct path link = path;
void *cookie;
if (!(nd->flags & LOOKUP_FOLLOW)) {
path_put_conditional(&path, nd);
path_put(&nd->path);
- filp = ERR_PTR(-ELOOP);
+ error = -ELOOP;
break;
}
+ error = may_follow_link(&link, nd);
+ if (unlikely(error))
+ break;
nd->flags |= LOOKUP_PARENT;
nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
error = follow_link(&link, nd, &cookie);
if (unlikely(error))
- filp = ERR_PTR(error);
- else
- filp = do_last(nd, &path, op, pathname);
+ break;
+ error = do_last(nd, &path, file, op, &opened, pathname);
put_link(nd, &link, cookie);
}
out:
path_put(&nd->root);
if (base)
fput(base);
- release_open_intent(nd);
- if (filp == ERR_PTR(-EOPENSTALE)) {
- if (flags & LOOKUP_RCU)
- filp = ERR_PTR(-ECHILD);
- else
- filp = ERR_PTR(-ESTALE);
+ if (!(opened & FILE_OPENED)) {
+ BUG_ON(!error);
+ put_filp(file);
}
- return filp;
-
-out_filp:
- filp = ERR_PTR(error);
- goto out;
+ if (unlikely(error)) {
+ if (error == -EOPENSTALE) {
+ if (flags & LOOKUP_RCU)
+ error = -ECHILD;
+ else
+ error = -ESTALE;
+ }
+ file = ERR_PTR(error);
+ }
+ return file;
}
struct file *do_filp_open(int dfd, const char *pathname,
{
struct dentry *dentry = ERR_PTR(-EEXIST);
struct nameidata nd;
+ int err2;
int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd);
if (error)
return ERR_PTR(error);
goto out;
nd.flags &= ~LOOKUP_PARENT;
nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL;
- nd.intent.open.flags = O_EXCL;
+ /* don't fail immediately if it's r/o, at least try to report other errors */
+ err2 = mnt_want_write(nd.path.mnt);
/*
* Do the final lookup.
*/
mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
dentry = lookup_hash(&nd);
if (IS_ERR(dentry))
- goto fail;
+ goto unlock;
+ error = -EEXIST;
if (dentry->d_inode)
- goto eexist;
+ goto fail;
/*
* Special case - lookup gave negative, but... we had foo/bar/
* From the vfs_mknod() POV we just have a negative dentry -
* been asking for (non-existent) directory. -ENOENT for you.
*/
if (unlikely(!is_dir && nd.last.name[nd.last.len])) {
- dput(dentry);
- dentry = ERR_PTR(-ENOENT);
+ error = -ENOENT;
+ goto fail;
+ }
+ if (unlikely(err2)) {
+ error = err2;
goto fail;
}
*path = nd.path;
return dentry;
-eexist:
- dput(dentry);
- dentry = ERR_PTR(-EEXIST);
fail:
+ dput(dentry);
+ dentry = ERR_PTR(error);
+unlock:
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
+ if (!err2)
+ mnt_drop_write(nd.path.mnt);
out:
path_put(&nd.path);
return dentry;
}
EXPORT_SYMBOL(kern_path_create);
+void done_path_create(struct path *path, struct dentry *dentry)
+{
+ dput(dentry);
+ mutex_unlock(&path->dentry->d_inode->i_mutex);
+ mnt_drop_write(path->mnt);
+ path_put(path);
+}
+EXPORT_SYMBOL(done_path_create);
+
struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir)
{
char *tmp = getname(pathname);
struct path path;
int error;
- if (S_ISDIR(mode))
- return -EPERM;
+ error = may_mknod(mode);
+ if (error)
+ return error;
dentry = user_path_create(dfd, filename, &path, 0);
if (IS_ERR(dentry))
if (!IS_POSIXACL(path.dentry->d_inode))
mode &= ~current_umask();
- error = may_mknod(mode);
- if (error)
- goto out_dput;
- error = mnt_want_write(path.mnt);
- if (error)
- goto out_dput;
error = security_path_mknod(&path, dentry, mode, dev);
if (error)
- goto out_drop_write;
+ goto out;
switch (mode & S_IFMT) {
case 0: case S_IFREG:
- error = vfs_create(path.dentry->d_inode,dentry,mode,NULL);
+ error = vfs_create(path.dentry->d_inode,dentry,mode,true);
break;
case S_IFCHR: case S_IFBLK:
error = vfs_mknod(path.dentry->d_inode,dentry,mode,
error = vfs_mknod(path.dentry->d_inode,dentry,mode,0);
break;
}
-out_drop_write:
- mnt_drop_write(path.mnt);
-out_dput:
- dput(dentry);
- mutex_unlock(&path.dentry->d_inode->i_mutex);
- path_put(&path);
-
+out:
+ done_path_create(&path, dentry);
return error;
}
if (!IS_POSIXACL(path.dentry->d_inode))
mode &= ~current_umask();
- error = mnt_want_write(path.mnt);
- if (error)
- goto out_dput;
error = security_path_mkdir(&path, dentry, mode);
- if (error)
- goto out_drop_write;
- error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
-out_drop_write:
- mnt_drop_write(path.mnt);
-out_dput:
- dput(dentry);
- mutex_unlock(&path.dentry->d_inode->i_mutex);
- path_put(&path);
+ if (!error)
+ error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
+ done_path_create(&path, dentry);
return error;
}
}
nd.flags &= ~LOOKUP_PARENT;
+ error = mnt_want_write(nd.path.mnt);
+ if (error)
+ goto exit1;
mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
dentry = lookup_hash(&nd);
error = -ENOENT;
goto exit3;
}
- error = mnt_want_write(nd.path.mnt);
- if (error)
- goto exit3;
error = security_path_rmdir(&nd.path, dentry);
if (error)
- goto exit4;
+ goto exit3;
error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
-exit4:
- mnt_drop_write(nd.path.mnt);
exit3:
dput(dentry);
exit2:
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
+ mnt_drop_write(nd.path.mnt);
exit1:
path_put(&nd.path);
putname(name);
goto exit1;
nd.flags &= ~LOOKUP_PARENT;
+ error = mnt_want_write(nd.path.mnt);
+ if (error)
+ goto exit1;
mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
dentry = lookup_hash(&nd);
if (!inode)
goto slashes;
ihold(inode);
- error = mnt_want_write(nd.path.mnt);
- if (error)
- goto exit2;
error = security_path_unlink(&nd.path, dentry);
if (error)
- goto exit3;
+ goto exit2;
error = vfs_unlink(nd.path.dentry->d_inode, dentry);
-exit3:
- mnt_drop_write(nd.path.mnt);
- exit2:
+exit2:
dput(dentry);
}
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
if (inode)
iput(inode); /* truncate the inode here */
+ mnt_drop_write(nd.path.mnt);
exit1:
path_put(&nd.path);
putname(name);
if (IS_ERR(dentry))
goto out_putname;
- error = mnt_want_write(path.mnt);
- if (error)
- goto out_dput;
error = security_path_symlink(&path, dentry, from);
- if (error)
- goto out_drop_write;
- error = vfs_symlink(path.dentry->d_inode, dentry, from);
-out_drop_write:
- mnt_drop_write(path.mnt);
-out_dput:
- dput(dentry);
- mutex_unlock(&path.dentry->d_inode->i_mutex);
- path_put(&path);
+ if (!error)
+ error = vfs_symlink(path.dentry->d_inode, dentry, from);
+ done_path_create(&path, dentry);
out_putname:
putname(from);
return error;
error = -EXDEV;
if (old_path.mnt != new_path.mnt)
goto out_dput;
- error = mnt_want_write(new_path.mnt);
- if (error)
+ error = may_linkat(&old_path);
+ if (unlikely(error))
goto out_dput;
error = security_path_link(old_path.dentry, &new_path, new_dentry);
if (error)
- goto out_drop_write;
+ goto out_dput;
error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry);
-out_drop_write:
- mnt_drop_write(new_path.mnt);
out_dput:
- dput(new_dentry);
- mutex_unlock(&new_path.dentry->d_inode->i_mutex);
- path_put(&new_path);
+ done_path_create(&new_path, new_dentry);
out:
path_put(&old_path);
if (newnd.last_type != LAST_NORM)
goto exit2;
+ error = mnt_want_write(oldnd.path.mnt);
+ if (error)
+ goto exit2;
+
oldnd.flags &= ~LOOKUP_PARENT;
newnd.flags &= ~LOOKUP_PARENT;
newnd.flags |= LOOKUP_RENAME_TARGET;
if (new_dentry == trap)
goto exit5;
- error = mnt_want_write(oldnd.path.mnt);
- if (error)
- goto exit5;
error = security_path_rename(&oldnd.path, old_dentry,
&newnd.path, new_dentry);
if (error)
- goto exit6;
+ goto exit5;
error = vfs_rename(old_dir->d_inode, old_dentry,
new_dir->d_inode, new_dentry);
-exit6:
- mnt_drop_write(oldnd.path.mnt);
exit5:
dput(new_dentry);
exit4:
dput(old_dentry);
exit3:
unlock_rename(new_dir, old_dir);
+ mnt_drop_write(oldnd.path.mnt);
exit2:
path_put(&newnd.path);
putname(to);
projects / ~andy / linux / blobdiff