vfs: don't BUG_ON() if following a /proc fd pseudo-symlink results in a symlink

[profile/ivi/kernel-adaptation-intel-automotive.git] / fs / namei.c

diff --git a/fs/namei.c b/fs/namei.c
index 8f8e41f..ec97aef 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -693,8 +693,6 @@ void nd_jump_link(struct nameidata *nd, struct path *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)
@@ -2175,15 +2173,19 @@ int user_path_at(int dfd, const char __user *name, unsigned flags,
  *     path-walking is complete.
  */
 static struct filename *
-user_path_parent(int dfd, const char __user *path, struct nameidata *nd)
+user_path_parent(int dfd, const char __user *path, struct nameidata *nd,
+                unsigned int flags)
 {
        struct filename *s = getname(path);
        int error;
 
+       /* only LOOKUP_REVAL is allowed in extra flags */
+       flags &= LOOKUP_REVAL;
+
        if (IS_ERR(s))
                return s;
 
-       error = filename_lookup(dfd, s, LOOKUP_PARENT, nd);
+       error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, nd);
        if (error) {
                putname(s);
                return ERR_PTR(error);
@@ -3172,12 +3174,13 @@ SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode,
        struct dentry *dentry;
        struct path path;
        int error;
+       unsigned int lookup_flags = 0;
 
        error = may_mknod(mode);
        if (error)
                return error;
-
-       dentry = user_path_create(dfd, filename, &path, 0);
+retry:
+       dentry = user_path_create(dfd, filename, &path, lookup_flags);
        if (IS_ERR(dentry))
                return PTR_ERR(dentry);
 
@@ -3200,6 +3203,10 @@ SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode,
        }
 out:
        done_path_create(&path, dentry);
+       if (retry_estale(error, lookup_flags)) {
+               lookup_flags |= LOOKUP_REVAL;
+               goto retry;
+       }
        return error;
 }
 
@@ -3238,8 +3245,10 @@ SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode)
        struct dentry *dentry;
        struct path path;
        int error;
+       unsigned int lookup_flags = LOOKUP_DIRECTORY;
 
-       dentry = user_path_create(dfd, pathname, &path, LOOKUP_DIRECTORY);
+retry:
+       dentry = user_path_create(dfd, pathname, &path, lookup_flags);
        if (IS_ERR(dentry))
                return PTR_ERR(dentry);
 
@@ -3249,6 +3258,10 @@ SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode)
        if (!error)
                error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
        done_path_create(&path, dentry);
+       if (retry_estale(error, lookup_flags)) {
+               lookup_flags |= LOOKUP_REVAL;
+               goto retry;
+       }
        return error;
 }
 
@@ -3324,8 +3337,9 @@ static long do_rmdir(int dfd, const char __user *pathname)
        struct filename *name;
        struct dentry *dentry;
        struct nameidata nd;
-
-       name = user_path_parent(dfd, pathname, &nd);
+       unsigned int lookup_flags = 0;
+retry:
+       name = user_path_parent(dfd, pathname, &nd, lookup_flags);
        if (IS_ERR(name))
                return PTR_ERR(name);
 
@@ -3367,6 +3381,10 @@ exit2:
 exit1:
        path_put(&nd.path);
        putname(name);
+       if (retry_estale(error, lookup_flags)) {
+               lookup_flags |= LOOKUP_REVAL;
+               goto retry;
+       }
        return error;
 }
 
@@ -3420,8 +3438,9 @@ static long do_unlinkat(int dfd, const char __user *pathname)
        struct dentry *dentry;
        struct nameidata nd;
        struct inode *inode = NULL;
-
-       name = user_path_parent(dfd, pathname, &nd);
+       unsigned int lookup_flags = 0;
+retry:
+       name = user_path_parent(dfd, pathname, &nd, lookup_flags);
        if (IS_ERR(name))
                return PTR_ERR(name);
 
@@ -3459,6 +3478,11 @@ exit2:
 exit1:
        path_put(&nd.path);
        putname(name);
+       if (retry_estale(error, lookup_flags)) {
+               lookup_flags |= LOOKUP_REVAL;
+               inode = NULL;
+               goto retry;
+       }
        return error;
 
 slashes:
@@ -3510,12 +3534,13 @@ SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
        struct filename *from;
        struct dentry *dentry;
        struct path path;
+       unsigned int lookup_flags = 0;
 
        from = getname(oldname);
        if (IS_ERR(from))
                return PTR_ERR(from);
-
-       dentry = user_path_create(newdfd, newname, &path, 0);
+retry:
+       dentry = user_path_create(newdfd, newname, &path, lookup_flags);
        error = PTR_ERR(dentry);
        if (IS_ERR(dentry))
                goto out_putname;
@@ -3524,6 +3549,10 @@ SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
        if (!error)
                error = vfs_symlink(path.dentry->d_inode, dentry, from->name);
        done_path_create(&path, dentry);
+       if (retry_estale(error, lookup_flags)) {
+               lookup_flags |= LOOKUP_REVAL;
+               goto retry;
+       }
 out_putname:
        putname(from);
        return error;
@@ -3610,12 +3639,13 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
 
        if (flags & AT_SYMLINK_FOLLOW)
                how |= LOOKUP_FOLLOW;
-
+retry:
        error = user_path_at(olddfd, oldname, how, &old_path);
        if (error)
                return error;
 
-       new_dentry = user_path_create(newdfd, newname, &new_path, 0);
+       new_dentry = user_path_create(newdfd, newname, &new_path,
+                                       (how & LOOKUP_REVAL));
        error = PTR_ERR(new_dentry);
        if (IS_ERR(new_dentry))
                goto out;
@@ -3632,6 +3662,10 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
        error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry);
 out_dput:
        done_path_create(&new_path, new_dentry);
+       if (retry_estale(error, how)) {
+               how |= LOOKUP_REVAL;
+               goto retry;
+       }
 out:
        path_put(&old_path);
 
@@ -3804,15 +3838,17 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
        struct nameidata oldnd, newnd;
        struct filename *from;
        struct filename *to;
+       unsigned int lookup_flags = 0;
+       bool should_retry = false;
        int error;
-
-       from = user_path_parent(olddfd, oldname, &oldnd);
+retry:
+       from = user_path_parent(olddfd, oldname, &oldnd, lookup_flags);
        if (IS_ERR(from)) {
                error = PTR_ERR(from);
                goto exit;
        }
 
-       to = user_path_parent(newdfd, newname, &newnd);
+       to = user_path_parent(newdfd, newname, &newnd, lookup_flags);
        if (IS_ERR(to)) {
                error = PTR_ERR(to);
                goto exit1;
@@ -3884,11 +3920,18 @@ exit3:
        unlock_rename(new_dir, old_dir);
        mnt_drop_write(oldnd.path.mnt);
 exit2:
+       if (retry_estale(error, lookup_flags))
+               should_retry = true;
        path_put(&newnd.path);
        putname(to);
 exit1:
        path_put(&oldnd.path);
        putname(from);
+       if (should_retry) {
+               should_retry = false;
+               lookup_flags |= LOOKUP_REVAL;
+               goto retry;
+       }
 exit:
        return error;
 }