diff options
Diffstat (limited to 'fs/namei.c')
| -rw-r--r-- | fs/namei.c | 207 |
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); |