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authorMatt Fleming <matt.fleming@intel.com>2013-02-01 11:02:28 +0000
committerMatt Fleming <matt.fleming@intel.com>2013-02-12 12:41:54 +0000
commitda27a24383b2b10bf6ebd0db29b325548aafecb4 (patch)
treedb48f001f62af527e832fe2c1cd302b30e794b6a /drivers/firmware
parent47f531e8ba3bc3901a0c493f4252826c41dea1a1 (diff)
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>
Diffstat (limited to 'drivers/firmware')
-rw-r--r--drivers/firmware/efivars.c95
1 files changed, 93 insertions, 2 deletions
diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 868cea5cd4b8..8bcb5958f21a 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -1043,6 +1043,84 @@ static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
return -EINVAL;
};
+/*
+ * Compare two efivarfs file names.
+ *
+ * An efivarfs filename is composed of two parts,
+ *
+ * 1. A case-sensitive variable name
+ * 2. A case-insensitive GUID
+ *
+ * So we need to perform a case-sensitive match on part 1 and a
+ * case-insensitive match on part 2.
+ */
+static int efivarfs_d_compare(const struct dentry *parent, const struct inode *pinode,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str,
+ const struct qstr *name)
+{
+ int guid = len - GUID_LEN;
+
+ if (name->len != len)
+ return 1;
+
+ /* Case-sensitive compare for the variable name */
+ if (memcmp(str, name->name, guid))
+ return 1;
+
+ /* Case-insensitive compare for the GUID */
+ return strncasecmp(name->name + guid, str + guid, GUID_LEN);
+}
+
+static int efivarfs_d_hash(const struct dentry *dentry,
+ const struct inode *inode, struct qstr *qstr)
+{
+ unsigned long hash = init_name_hash();
+ const unsigned char *s = qstr->name;
+ unsigned int len = qstr->len;
+
+ if (!efivarfs_valid_name(s, len))
+ return -EINVAL;
+
+ while (len-- > GUID_LEN)
+ hash = partial_name_hash(*s++, hash);
+
+ /* GUID is case-insensitive. */
+ while (len--)
+ hash = partial_name_hash(tolower(*s++), hash);
+
+ qstr->hash = end_name_hash(hash);
+ return 0;
+}
+
+/*
+ * Retaining negative dentries for an in-memory filesystem just wastes
+ * memory and lookup time: arrange for them to be deleted immediately.
+ */
+static int efivarfs_delete_dentry(const struct dentry *dentry)
+{
+ return 1;
+}
+
+static struct dentry_operations efivarfs_d_ops = {
+ .d_compare = efivarfs_d_compare,
+ .d_hash = efivarfs_d_hash,
+ .d_delete = efivarfs_delete_dentry,
+};
+
+static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
+{
+ struct qstr q;
+
+ q.name = name;
+ q.len = strlen(name);
+
+ if (efivarfs_d_hash(NULL, NULL, &q))
+ return NULL;
+
+ return d_alloc(parent, &q);
+}
+
static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
{
struct inode *inode = NULL;
@@ -1058,6 +1136,7 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
sb->s_magic = EFIVARFS_MAGIC;
sb->s_op = &efivarfs_ops;
+ sb->s_d_op = &efivarfs_d_ops;
sb->s_time_gran = 1;
inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0);
@@ -1098,7 +1177,7 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
if (!inode)
goto fail_name;
- dentry = d_alloc_name(root, name);
+ dentry = efivarfs_alloc_dentry(root, name);
if (!dentry)
goto fail_inode;
@@ -1148,8 +1227,20 @@ static struct file_system_type efivarfs_type = {
.kill_sb = efivarfs_kill_sb,
};
+/*
+ * Handle negative dentry.
+ */
+static struct dentry *efivarfs_lookup(struct inode *dir, struct dentry *dentry,
+ unsigned int flags)
+{
+ if (dentry->d_name.len > NAME_MAX)
+ return ERR_PTR(-ENAMETOOLONG);
+ d_add(dentry, NULL);
+ return NULL;
+}
+
static const struct inode_operations efivarfs_dir_inode_operations = {
- .lookup = simple_lookup,
+ .lookup = efivarfs_lookup,
.unlink = efivarfs_unlink,
.create = efivarfs_create,
};

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