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scoutfs: add scoutfs xattr prefix and name tags

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Add a scoutfs. xattr prefix which then defines a series of following
tags which can change the behaviour of the xattr.  We start with .hide.
which stops the xattr from showing up in listxattr.

Signed-off-by: Zach Brown <zab@versity.com>
This commit is contained in:
Zach Brown
2019-06-14 14:32:21 -07:00
committed by Zach Brown
parent a239f6093d
commit 019b5f6d6b
1 changed files with 59 additions and 10 deletions
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69
kmod/src/xattr.c
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@@ -81,12 +81,51 @@ static void init_xattr_key(struct scoutfs_key *key, u64 ino, u32 name_hash,
};
}
#define SCOUTFS_XATTR_PREFIX "scoutfs."
#define SCOUTFS_XATTR_PREFIX_LEN (sizeof(SCOUTFS_XATTR_PREFIX) - 1)
static int unknown_prefix(const char *name)
{
return strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN) &&
strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) &&
strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) &&
strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN);
strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)&&
strncmp(name, SCOUTFS_XATTR_PREFIX, SCOUTFS_XATTR_PREFIX_LEN);
}
struct prefix_tags {
unsigned long hide:1;
};
#define HIDE_TAG "hide."
#define HIDE_TAG_LEN (sizeof(HIDE_TAG) - 1)
static int parse_tags(const char *name, struct prefix_tags *tgs)
{
bool found;
memset(tgs, 0, sizeof(struct prefix_tags));
if (strncmp(name, SCOUTFS_XATTR_PREFIX, SCOUTFS_XATTR_PREFIX_LEN))
return 0;
name += SCOUTFS_XATTR_PREFIX_LEN;
found = false;
for (;;) {
if (!strncmp(name, HIDE_TAG, HIDE_TAG_LEN)) {
if (++tgs->hide == 0)
return -EINVAL;
name += HIDE_TAG_LEN;
} else {
/* only reason to use scoutfs. is tags */
if (!found)
return -EINVAL;
break;
}
found = true;
}
return 0;
}
/*
@@ -355,6 +394,7 @@ static int scoutfs_xattr_set(struct dentry *dentry, const char *name,
struct scoutfs_lock *lck = NULL;
size_t name_len = strlen(name);
struct scoutfs_key key;
struct prefix_tags tgs;
LIST_HEAD(ind_locks);
LIST_HEAD(saved);
u8 found_parts;
@@ -378,6 +418,12 @@ static int scoutfs_xattr_set(struct dentry *dentry, const char *name,
if (unknown_prefix(name))
return -EOPNOTSUPP;
if (parse_tags(name, &tgs) != 0)
return -EINVAL;
if (tgs.hide && !capable(CAP_SYS_ADMIN))
return -EPERM;
bytes = sizeof(struct scoutfs_xattr) + name_len + size;
xat = kmalloc(bytes, GFP_NOFS);
if (!xat) {
@@ -495,6 +541,7 @@ ssize_t scoutfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
struct scoutfs_xattr *xat = NULL;
struct scoutfs_lock *lck = NULL;
struct scoutfs_key key;
struct prefix_tags tgs;
unsigned int bytes;
ssize_t total;
u32 name_hash;
@@ -528,17 +575,19 @@ ssize_t scoutfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
break;
}
total += xat->name_len + 1;
if (parse_tags(xat->name, &tgs) != 0 || !tgs.hide) {
total += xat->name_len + 1;
if (size) {
if (total > size) {
ret = -ERANGE;
break;
if (size) {
if (total > size) {
ret = -ERANGE;
break;
}
memcpy(buffer, xat->name, xat->name_len);
buffer += xat->name_len;
*(buffer++) = '\0';
}
memcpy(buffer, xat->name, xat->name_len);
buffer += xat->name_len;
*(buffer++) = '\0';
}
name_hash = le64_to_cpu(key.skx_name_hash);