mirror of https://gitee.com/openkylin/linux.git
efivarfs: guid part of filenames are case-insensitive
It makes no sense to treat the following filenames as unique, VarName-abcdefab-abcd-abcd-abcd-abcdefabcdef VarName-ABCDEFAB-ABCD-ABCD-ABCD-ABCDEFABCDEF VarName-ABcDEfAB-ABcD-ABcD-ABcD-ABcDEfABcDEf VarName-aBcDEfAB-aBcD-aBcD-aBcD-aBcDEfaBcDEf ... etc ... since the guid will be converted into a binary representation, which has no case. Roll our own dentry operations so that we can treat the variable name part of filenames ("VarName" in the above example) as case-sensitive, but the guid portion as case-insensitive. That way, efivarfs will refuse to create the above files if any one already exists. Reported-by: Lingzhu Xiang <lxiang@redhat.com> Cc: Matthew Garrett <mjg59@srcf.ucam.org> Cc: Jeremy Kerr <jeremy.kerr@canonical.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Matt Fleming <matt.fleming@intel.com>
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@ -1043,6 +1043,84 @@ static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
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return -EINVAL;
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};
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/*
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* Compare two efivarfs file names.
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*
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* An efivarfs filename is composed of two parts,
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*
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* 1. A case-sensitive variable name
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* 2. A case-insensitive GUID
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*
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* So we need to perform a case-sensitive match on part 1 and a
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* case-insensitive match on part 2.
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*/
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static int efivarfs_d_compare(const struct dentry *parent, const struct inode *pinode,
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const struct dentry *dentry, const struct inode *inode,
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unsigned int len, const char *str,
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const struct qstr *name)
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{
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int guid = len - GUID_LEN;
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if (name->len != len)
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return 1;
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/* Case-sensitive compare for the variable name */
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if (memcmp(str, name->name, guid))
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return 1;
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/* Case-insensitive compare for the GUID */
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return strncasecmp(name->name + guid, str + guid, GUID_LEN);
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}
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static int efivarfs_d_hash(const struct dentry *dentry,
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const struct inode *inode, struct qstr *qstr)
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{
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unsigned long hash = init_name_hash();
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const unsigned char *s = qstr->name;
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unsigned int len = qstr->len;
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if (!efivarfs_valid_name(s, len))
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return -EINVAL;
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while (len-- > GUID_LEN)
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hash = partial_name_hash(*s++, hash);
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/* GUID is case-insensitive. */
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while (len--)
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hash = partial_name_hash(tolower(*s++), hash);
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qstr->hash = end_name_hash(hash);
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return 0;
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}
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/*
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* Retaining negative dentries for an in-memory filesystem just wastes
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* memory and lookup time: arrange for them to be deleted immediately.
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*/
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static int efivarfs_delete_dentry(const struct dentry *dentry)
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{
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return 1;
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}
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static struct dentry_operations efivarfs_d_ops = {
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.d_compare = efivarfs_d_compare,
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.d_hash = efivarfs_d_hash,
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.d_delete = efivarfs_delete_dentry,
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};
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static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
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{
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struct qstr q;
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q.name = name;
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q.len = strlen(name);
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if (efivarfs_d_hash(NULL, NULL, &q))
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return NULL;
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return d_alloc(parent, &q);
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}
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static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
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{
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struct inode *inode = NULL;
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@ -1058,6 +1136,7 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
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sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
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sb->s_magic = EFIVARFS_MAGIC;
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sb->s_op = &efivarfs_ops;
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sb->s_d_op = &efivarfs_d_ops;
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sb->s_time_gran = 1;
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inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0);
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@ -1098,7 +1177,7 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
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if (!inode)
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goto fail_name;
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dentry = d_alloc_name(root, name);
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dentry = efivarfs_alloc_dentry(root, name);
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if (!dentry)
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goto fail_inode;
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@ -1148,8 +1227,20 @@ static struct file_system_type efivarfs_type = {
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.kill_sb = efivarfs_kill_sb,
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};
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/*
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* Handle negative dentry.
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*/
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static struct dentry *efivarfs_lookup(struct inode *dir, struct dentry *dentry,
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unsigned int flags)
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{
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if (dentry->d_name.len > NAME_MAX)
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return ERR_PTR(-ENAMETOOLONG);
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d_add(dentry, NULL);
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return NULL;
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}
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static const struct inode_operations efivarfs_dir_inode_operations = {
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.lookup = simple_lookup,
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.lookup = efivarfs_lookup,
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.unlink = efivarfs_unlink,
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.create = efivarfs_create,
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};
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