From 3c95f0dce82186de657d828cce420daa0edd9a19 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Fri, 6 Apr 2018 16:32:38 -0400 Subject: merge common parts of lookup_one_len{,_unlocked} into common helper Signed-off-by: Al Viro --- fs/namei.c | 90 ++++++++++++++++++++++++-------------------------------------- 1 file changed, 34 insertions(+), 56 deletions(-) (limited to 'fs/namei.c') diff --git a/fs/namei.c b/fs/namei.c index a3cd028e8a9b..b803c6c6ac95 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2417,52 +2417,57 @@ int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, } EXPORT_SYMBOL(vfs_path_lookup); -/** - * lookup_one_len - filesystem helper to lookup single pathname component - * @name: pathname component to lookup - * @base: base directory to lookup from - * @len: maximum length @len should be interpreted to - * - * Note that this routine is purely a helper for filesystem usage and should - * not be called by generic code. - * - * The caller must hold base->i_mutex. - */ -struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) +static int lookup_one_len_common(const char *name, struct dentry *base, + int len, struct qstr *this) { - struct qstr this; - unsigned int c; - int err; - - WARN_ON_ONCE(!inode_is_locked(base->d_inode)); - - this.name = name; - this.len = len; - this.hash = full_name_hash(base, name, len); + this->name = name; + this->len = len; + this->hash = full_name_hash(base, name, len); if (!len) - return ERR_PTR(-EACCES); + return -EACCES; if (unlikely(name[0] == '.')) { if (len < 2 || (len == 2 && name[1] == '.')) - return ERR_PTR(-EACCES); + return -EACCES; } while (len--) { - c = *(const unsigned char *)name++; + unsigned int c = *(const unsigned char *)name++; if (c == '/' || c == '\0') - return ERR_PTR(-EACCES); + return -EACCES; } /* * See if the low-level filesystem might want * to use its own hash.. */ if (base->d_flags & DCACHE_OP_HASH) { - int err = base->d_op->d_hash(base, &this); + int err = base->d_op->d_hash(base, this); if (err < 0) - return ERR_PTR(err); + return err; } - err = inode_permission(base->d_inode, MAY_EXEC); + return inode_permission(base->d_inode, MAY_EXEC); +} + +/** + * lookup_one_len - filesystem helper to lookup single pathname component + * @name: pathname component to lookup + * @base: base directory to lookup from + * @len: maximum length @len should be interpreted to + * + * Note that this routine is purely a helper for filesystem usage and should + * not be called by generic code. + * + * The caller must hold base->i_mutex. + */ +struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) +{ + struct qstr this; + int err; + + WARN_ON_ONCE(!inode_is_locked(base->d_inode)); + + err = lookup_one_len_common(name, base, len, &this); if (err) return ERR_PTR(err); @@ -2486,37 +2491,10 @@ struct dentry *lookup_one_len_unlocked(const char *name, struct dentry *base, int len) { struct qstr this; - unsigned int c; int err; struct dentry *ret; - this.name = name; - this.len = len; - this.hash = full_name_hash(base, name, len); - if (!len) - return ERR_PTR(-EACCES); - - if (unlikely(name[0] == '.')) { - if (len < 2 || (len == 2 && name[1] == '.')) - return ERR_PTR(-EACCES); - } - - while (len--) { - c = *(const unsigned char *)name++; - if (c == '/' || c == '\0') - return ERR_PTR(-EACCES); - } - /* - * See if the low-level filesystem might want - * to use its own hash.. - */ - if (base->d_flags & DCACHE_OP_HASH) { - int err = base->d_op->d_hash(base, &this); - if (err < 0) - return ERR_PTR(err); - } - - err = inode_permission(base->d_inode, MAY_EXEC); + err = lookup_one_len_common(name, base, len, &this); if (err) return ERR_PTR(err); -- cgit v1.2.3 From 88d8331afb0f76ad856770c49a0c0909d123b59c Mon Sep 17 00:00:00 2001 From: Al Viro Date: Fri, 6 Apr 2018 16:43:47 -0400 Subject: new helper: __lookup_slow() lookup_slow() sans locking/unlocking the directory Signed-off-by: Al Viro --- fs/namei.c | 27 ++++++++++++++++++--------- 1 file changed, 18 insertions(+), 9 deletions(-) (limited to 'fs/namei.c') diff --git a/fs/namei.c b/fs/namei.c index b803c6c6ac95..ba48e154409b 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1593,22 +1593,21 @@ static int lookup_fast(struct nameidata *nd, } /* Fast lookup failed, do it the slow way */ -static struct dentry *lookup_slow(const struct qstr *name, - struct dentry *dir, - unsigned int flags) +static struct dentry *__lookup_slow(const struct qstr *name, + struct dentry *dir, + unsigned int flags) { - struct dentry *dentry = ERR_PTR(-ENOENT), *old; + struct dentry *dentry, *old; struct inode *inode = dir->d_inode; DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); - inode_lock_shared(inode); /* Don't go there if it's already dead */ if (unlikely(IS_DEADDIR(inode))) - goto out; + return ERR_PTR(-ENOENT); again: dentry = d_alloc_parallel(dir, name, &wq); if (IS_ERR(dentry)) - goto out; + return dentry; if (unlikely(!d_in_lookup(dentry))) { if (!(flags & LOOKUP_NO_REVAL)) { int error = d_revalidate(dentry, flags); @@ -1630,11 +1629,21 @@ again: dentry = old; } } -out: - inode_unlock_shared(inode); return dentry; } +static struct dentry *lookup_slow(const struct qstr *name, + struct dentry *dir, + unsigned int flags) +{ + struct inode *inode = dir->d_inode; + struct dentry *res; + inode_lock_shared(inode); + res = __lookup_slow(name, dir, flags); + inode_unlock_shared(inode); + return res; +} + static inline int may_lookup(struct nameidata *nd) { if (nd->flags & LOOKUP_RCU) { -- cgit v1.2.3 From 8613a209ffa6dd2c19c405fa699a062035dec9b0 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Fri, 6 Apr 2018 16:45:33 -0400 Subject: make lookup_one_len() safe to use with directory locked shared Signed-off-by: Al Viro --- fs/namei.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'fs/namei.c') diff --git a/fs/namei.c b/fs/namei.c index ba48e154409b..6e0f6eea9896 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2471,6 +2471,7 @@ static int lookup_one_len_common(const char *name, struct dentry *base, */ struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) { + struct dentry *dentry; struct qstr this; int err; @@ -2480,7 +2481,8 @@ struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) if (err) return ERR_PTR(err); - return __lookup_hash(&this, base, 0); + dentry = lookup_dcache(&this, base, 0); + return dentry ? dentry : __lookup_slow(&this, base, 0); } EXPORT_SYMBOL(lookup_one_len); -- cgit v1.2.3 From 30ce4d1903e1d8a7ccd110860a5eef3c638ed8be Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sun, 8 Apr 2018 11:57:10 -0400 Subject: getname_kernel() needs to make sure that ->name != ->iname in long case missed it in "kill struct filename.separate" several years ago. Cc: stable@vger.kernel.org Signed-off-by: Al Viro --- fs/namei.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'fs/namei.c') diff --git a/fs/namei.c b/fs/namei.c index 6e0f6eea9896..3aefcf74f041 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -222,9 +222,10 @@ getname_kernel(const char * filename) if (len <= EMBEDDED_NAME_MAX) { result->name = (char *)result->iname; } else if (len <= PATH_MAX) { + const size_t size = offsetof(struct filename, iname[1]); struct filename *tmp; - tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); + tmp = kmalloc(size, GFP_KERNEL); if (unlikely(!tmp)) { __putname(result); return ERR_PTR(-ENOMEM); -- cgit v1.2.3