Commit c8c57e84 authored by Tetsuo Handa's avatar Tetsuo Handa Committed by James Morris

TOMOYO: Support longer pathname.

Allow pathnames longer than 4000 bytes.
Signed-off-by: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: default avatarJames Morris <jmorris@namei.org>
parent 9b244373
......@@ -33,14 +33,7 @@ struct linux_binprm;
#define TOMOYO_HASH_BITS 8
#define TOMOYO_MAX_HASH (1u<<TOMOYO_HASH_BITS)
/*
* This is the max length of a token.
*
* A token consists of only ASCII printable characters.
* Non printable characters in a token is represented in \ooo style
* octal string. Thus, \ itself is represented as \\.
*/
#define TOMOYO_MAX_PATHNAME_LEN 4000
#define TOMOYO_EXEC_TMPSIZE 4096
/* Profile number is an integer between 0 and 255. */
#define TOMOYO_MAX_PROFILES 256
......@@ -167,17 +160,6 @@ enum tomoyo_securityfs_interface_index {
/********** Structure definitions. **********/
/*
* tomoyo_page_buffer is a structure which is used for holding a pathname
* obtained from "struct dentry" and "struct vfsmount" pair.
* As of now, it is 4096 bytes. If users complain that 4096 bytes is too small
* (because TOMOYO escapes non ASCII printable characters using \ooo format),
* we will make the buffer larger.
*/
struct tomoyo_page_buffer {
char buffer[4096];
};
/*
* tomoyo_request_info is a structure which is used for holding
*
......@@ -231,28 +213,6 @@ struct tomoyo_name_entry {
struct tomoyo_path_info entry;
};
/*
* tomoyo_path_info_with_data is a structure which is used for holding a
* pathname obtained from "struct dentry" and "struct vfsmount" pair.
*
* "struct tomoyo_path_info_with_data" consists of "struct tomoyo_path_info"
* and buffer for the pathname, while "struct tomoyo_page_buffer" consists of
* buffer for the pathname only.
*
* "struct tomoyo_path_info_with_data" is intended to allow TOMOYO to release
* both "struct tomoyo_path_info" and buffer for the pathname by single kfree()
* so that we don't need to return two pointers to the caller. If the caller
* puts "struct tomoyo_path_info" on stack memory, we will be able to remove
* "struct tomoyo_path_info_with_data".
*/
struct tomoyo_path_info_with_data {
/* Keep "head" first, for this pointer is passed to kfree(). */
struct tomoyo_path_info head;
char barrier1[16]; /* Safeguard for overrun. */
char body[TOMOYO_MAX_PATHNAME_LEN];
char barrier2[16]; /* Safeguard for overrun. */
};
struct tomoyo_name_union {
const struct tomoyo_path_info *filename;
struct tomoyo_path_group *group;
......@@ -827,11 +787,7 @@ void tomoyo_load_policy(const char *filename);
void tomoyo_put_number_union(struct tomoyo_number_union *ptr);
/* Convert binary string to ascii string. */
int tomoyo_encode(char *buffer, int buflen, const char *str);
/* Returns realpath(3) of the given pathname but ignores chroot'ed root. */
int tomoyo_realpath_from_path2(struct path *path, char *newname,
int newname_len);
char *tomoyo_encode(const char *str);
/*
* Returns realpath(3) of the given pathname but ignores chroot'ed root.
......
......@@ -676,47 +676,43 @@ struct tomoyo_domain_info *tomoyo_find_or_assign_new_domain(const char *
int tomoyo_find_next_domain(struct linux_binprm *bprm)
{
struct tomoyo_request_info r;
/*
* This function assumes that the size of buffer returned by
* tomoyo_realpath() = TOMOYO_MAX_PATHNAME_LEN.
*/
struct tomoyo_page_buffer *tmp = kzalloc(sizeof(*tmp), GFP_NOFS);
char *tmp = kzalloc(TOMOYO_EXEC_TMPSIZE, GFP_NOFS);
struct tomoyo_domain_info *old_domain = tomoyo_domain();
struct tomoyo_domain_info *domain = NULL;
const char *old_domain_name = old_domain->domainname->name;
const char *original_name = bprm->filename;
char *new_domain_name = NULL;
char *real_program_name = NULL;
char *symlink_program_name = NULL;
const u8 mode = tomoyo_check_flags(old_domain, TOMOYO_MAC_FOR_FILE);
const bool is_enforce = (mode == TOMOYO_CONFIG_ENFORCING);
int retval = -ENOMEM;
struct tomoyo_path_info rn; /* real name */
struct tomoyo_path_info sn; /* symlink name */
bool need_kfree = false;
struct tomoyo_path_info rn = { }; /* real name */
struct tomoyo_path_info sn = { }; /* symlink name */
struct tomoyo_path_info ln; /* last name */
ln.name = tomoyo_get_last_name(old_domain);
tomoyo_fill_path_info(&ln);
tomoyo_init_request_info(&r, NULL);
if (!tmp)
goto out;
retry:
if (need_kfree) {
kfree(rn.name);
need_kfree = false;
}
/* Get tomoyo_realpath of program. */
retval = -ENOENT;
/* I hope tomoyo_realpath() won't fail with -ENOMEM. */
real_program_name = tomoyo_realpath(original_name);
if (!real_program_name)
rn.name = tomoyo_realpath(original_name);
if (!rn.name)
goto out;
tomoyo_fill_path_info(&rn);
need_kfree = true;
/* Get tomoyo_realpath of symbolic link. */
symlink_program_name = tomoyo_realpath_nofollow(original_name);
if (!symlink_program_name)
sn.name = tomoyo_realpath_nofollow(original_name);
if (!sn.name)
goto out;
rn.name = real_program_name;
tomoyo_fill_path_info(&rn);
sn.name = symlink_program_name;
tomoyo_fill_path_info(&sn);
ln.name = tomoyo_get_last_name(old_domain);
tomoyo_fill_path_info(&ln);
/* Check 'alias' directive. */
if (tomoyo_pathcmp(&rn, &sn)) {
......@@ -727,10 +723,10 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
tomoyo_pathcmp(&rn, ptr->original_name) ||
tomoyo_pathcmp(&sn, ptr->aliased_name))
continue;
memset(real_program_name, 0, TOMOYO_MAX_PATHNAME_LEN);
strncpy(real_program_name, ptr->aliased_name->name,
TOMOYO_MAX_PATHNAME_LEN - 1);
tomoyo_fill_path_info(&rn);
kfree(rn.name);
need_kfree = false;
/* This is OK because it is read only. */
rn = *ptr->aliased_name;
break;
}
}
......@@ -742,11 +738,10 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
if (retval < 0)
goto out;
new_domain_name = tmp->buffer;
if (tomoyo_is_domain_initializer(old_domain->domainname, &rn, &ln)) {
/* Transit to the child of tomoyo_kernel_domain domain. */
snprintf(new_domain_name, TOMOYO_MAX_PATHNAME_LEN + 1,
TOMOYO_ROOT_NAME " " "%s", real_program_name);
snprintf(tmp, TOMOYO_EXEC_TMPSIZE - 1,
TOMOYO_ROOT_NAME " " "%s", rn.name);
} else if (old_domain == &tomoyo_kernel_domain &&
!tomoyo_policy_loaded) {
/*
......@@ -760,29 +755,27 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
domain = old_domain;
} else {
/* Normal domain transition. */
snprintf(new_domain_name, TOMOYO_MAX_PATHNAME_LEN + 1,
"%s %s", old_domain_name, real_program_name);
snprintf(tmp, TOMOYO_EXEC_TMPSIZE - 1,
"%s %s", old_domain_name, rn.name);
}
if (domain || strlen(new_domain_name) >= TOMOYO_MAX_PATHNAME_LEN)
if (domain || strlen(tmp) >= TOMOYO_EXEC_TMPSIZE - 10)
goto done;
domain = tomoyo_find_domain(new_domain_name);
domain = tomoyo_find_domain(tmp);
if (domain)
goto done;
if (is_enforce) {
int error = tomoyo_supervisor(&r, "# wants to create domain\n"
"%s\n", new_domain_name);
"%s\n", tmp);
if (error == TOMOYO_RETRY_REQUEST)
goto retry;
if (error < 0)
goto done;
}
domain = tomoyo_find_or_assign_new_domain(new_domain_name,
old_domain->profile);
domain = tomoyo_find_or_assign_new_domain(tmp, old_domain->profile);
done:
if (domain)
goto out;
printk(KERN_WARNING "TOMOYO-ERROR: Domain '%s' not defined.\n",
new_domain_name);
printk(KERN_WARNING "TOMOYO-ERROR: Domain '%s' not defined.\n", tmp);
if (is_enforce)
retval = -EPERM;
else
......@@ -793,8 +786,9 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
/* Update reference count on "struct tomoyo_domain_info". */
atomic_inc(&domain->users);
bprm->cred->security = domain;
kfree(real_program_name);
kfree(symlink_program_name);
if (need_kfree)
kfree(rn.name);
kfree(sn.name);
kfree(tmp);
return retval;
}
......@@ -148,6 +148,17 @@ const char *tomoyo_path_number2keyword(const u8 operation)
? tomoyo_path_number_keyword[operation] : NULL;
}
static void tomoyo_add_slash(struct tomoyo_path_info *buf)
{
if (buf->is_dir)
return;
/*
* This is OK because tomoyo_encode() reserves space for appending "/".
*/
strcat((char *) buf->name, "/");
tomoyo_fill_path_info(buf);
}
/**
* tomoyo_strendswith - Check whether the token ends with the given token.
*
......@@ -167,30 +178,21 @@ static bool tomoyo_strendswith(const char *name, const char *tail)
}
/**
* tomoyo_get_path - Get realpath.
* tomoyo_get_realpath - Get realpath.
*
* @buf: Pointer to "struct tomoyo_path_info".
* @path: Pointer to "struct path".
*
* Returns pointer to "struct tomoyo_path_info" on success, NULL otherwise.
* Returns true on success, false otherwise.
*/
static struct tomoyo_path_info *tomoyo_get_path(struct path *path)
static bool tomoyo_get_realpath(struct tomoyo_path_info *buf, struct path *path)
{
int error;
struct tomoyo_path_info_with_data *buf = kzalloc(sizeof(*buf),
GFP_NOFS);
if (!buf)
return NULL;
/* Reserve one byte for appending "/". */
error = tomoyo_realpath_from_path2(path, buf->body,
sizeof(buf->body) - 2);
if (!error) {
buf->head.name = buf->body;
tomoyo_fill_path_info(&buf->head);
return &buf->head;
buf->name = tomoyo_realpath_from_path(path);
if (buf->name) {
tomoyo_fill_path_info(buf);
return true;
}
kfree(buf);
return NULL;
return false;
}
static int tomoyo_update_path2_acl(const u8 type, const char *filename1,
......@@ -1259,26 +1261,20 @@ int tomoyo_path_number_perm(const u8 type, struct path *path,
{
struct tomoyo_request_info r;
int error = -ENOMEM;
struct tomoyo_path_info *buf;
struct tomoyo_path_info buf;
int idx;
if (tomoyo_init_request_info(&r, NULL) == TOMOYO_CONFIG_DISABLED ||
!path->mnt || !path->dentry)
return 0;
idx = tomoyo_read_lock();
buf = tomoyo_get_path(path);
if (!buf)
if (!tomoyo_get_realpath(&buf, path))
goto out;
if (type == TOMOYO_TYPE_MKDIR && !buf->is_dir) {
/*
* tomoyo_get_path() reserves space for appending "/."
*/
strcat((char *) buf->name, "/");
tomoyo_fill_path_info(buf);
}
error = tomoyo_path_number_perm2(&r, type, buf, number);
if (type == TOMOYO_TYPE_MKDIR)
tomoyo_add_slash(&buf);
error = tomoyo_path_number_perm2(&r, type, &buf, number);
out:
kfree(buf);
kfree(buf.name);
tomoyo_read_unlock(idx);
if (r.mode != TOMOYO_CONFIG_ENFORCING)
error = 0;
......@@ -1319,7 +1315,7 @@ int tomoyo_check_open_permission(struct tomoyo_domain_info *domain,
{
const u8 acc_mode = ACC_MODE(flag);
int error = -ENOMEM;
struct tomoyo_path_info *buf;
struct tomoyo_path_info buf;
struct tomoyo_request_info r;
int idx;
......@@ -1335,8 +1331,7 @@ int tomoyo_check_open_permission(struct tomoyo_domain_info *domain,
*/
return 0;
idx = tomoyo_read_lock();
buf = tomoyo_get_path(path);
if (!buf)
if (!tomoyo_get_realpath(&buf, path))
goto out;
error = 0;
/*
......@@ -1346,15 +1341,15 @@ int tomoyo_check_open_permission(struct tomoyo_domain_info *domain,
*/
if ((acc_mode & MAY_WRITE) &&
((flag & O_TRUNC) || !(flag & O_APPEND)) &&
(tomoyo_is_no_rewrite_file(buf))) {
error = tomoyo_path_permission(&r, TOMOYO_TYPE_REWRITE, buf);
(tomoyo_is_no_rewrite_file(&buf))) {
error = tomoyo_path_permission(&r, TOMOYO_TYPE_REWRITE, &buf);
}
if (!error)
error = tomoyo_file_perm(&r, buf, acc_mode);
error = tomoyo_file_perm(&r, &buf, acc_mode);
if (!error && (flag & O_TRUNC))
error = tomoyo_path_permission(&r, TOMOYO_TYPE_TRUNCATE, buf);
error = tomoyo_path_permission(&r, TOMOYO_TYPE_TRUNCATE, &buf);
out:
kfree(buf);
kfree(buf.name);
tomoyo_read_unlock(idx);
if (r.mode != TOMOYO_CONFIG_ENFORCING)
error = 0;
......@@ -1372,7 +1367,7 @@ int tomoyo_check_open_permission(struct tomoyo_domain_info *domain,
int tomoyo_path_perm(const u8 operation, struct path *path)
{
int error = -ENOMEM;
struct tomoyo_path_info *buf;
struct tomoyo_path_info buf;
struct tomoyo_request_info r;
int idx;
......@@ -1380,29 +1375,23 @@ int tomoyo_path_perm(const u8 operation, struct path *path)
!path->mnt)
return 0;
idx = tomoyo_read_lock();
buf = tomoyo_get_path(path);
if (!buf)
if (!tomoyo_get_realpath(&buf, path))
goto out;
switch (operation) {
case TOMOYO_TYPE_REWRITE:
if (!tomoyo_is_no_rewrite_file(buf)) {
if (!tomoyo_is_no_rewrite_file(&buf)) {
error = 0;
goto out;
}
break;
case TOMOYO_TYPE_RMDIR:
case TOMOYO_TYPE_CHROOT:
if (!buf->is_dir) {
/*
* tomoyo_get_path() reserves space for appending "/."
*/
strcat((char *) buf->name, "/");
tomoyo_fill_path_info(buf);
}
tomoyo_add_slash(&buf);
break;
}
error = tomoyo_path_permission(&r, operation, buf);
error = tomoyo_path_permission(&r, operation, &buf);
out:
kfree(buf);
kfree(buf.name);
tomoyo_read_unlock(idx);
if (r.mode != TOMOYO_CONFIG_ENFORCING)
error = 0;
......@@ -1465,7 +1454,7 @@ int tomoyo_path_number3_perm(const u8 operation, struct path *path,
{
struct tomoyo_request_info r;
int error = -ENOMEM;
struct tomoyo_path_info *buf;
struct tomoyo_path_info buf;
int idx;
if (tomoyo_init_request_info(&r, NULL) == TOMOYO_CONFIG_DISABLED ||
......@@ -1473,11 +1462,10 @@ int tomoyo_path_number3_perm(const u8 operation, struct path *path,
return 0;
idx = tomoyo_read_lock();
error = -ENOMEM;
buf = tomoyo_get_path(path);
if (buf) {
error = tomoyo_path_number3_perm2(&r, operation, buf, mode,
if (tomoyo_get_realpath(&buf, path)) {
error = tomoyo_path_number3_perm2(&r, operation, &buf, mode,
new_decode_dev(dev));
kfree(buf);
kfree(buf.name);
}
tomoyo_read_unlock(idx);
if (r.mode != TOMOYO_CONFIG_ENFORCING)
......@@ -1499,48 +1487,40 @@ int tomoyo_path2_perm(const u8 operation, struct path *path1,
{
int error = -ENOMEM;
const char *msg;
struct tomoyo_path_info *buf1;
struct tomoyo_path_info *buf2;
struct tomoyo_path_info buf1;
struct tomoyo_path_info buf2;
struct tomoyo_request_info r;
int idx;
if (tomoyo_init_request_info(&r, NULL) == TOMOYO_CONFIG_DISABLED ||
!path1->mnt || !path2->mnt)
return 0;
buf1.name = NULL;
buf2.name = NULL;
idx = tomoyo_read_lock();
buf1 = tomoyo_get_path(path1);
buf2 = tomoyo_get_path(path2);
if (!buf1 || !buf2)
if (!tomoyo_get_realpath(&buf1, path1) ||
!tomoyo_get_realpath(&buf2, path2))
goto out;
{
struct dentry *dentry = path1->dentry;
if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) {
/*
* tomoyo_get_path() reserves space for appending "/."
*/
if (!buf1->is_dir) {
strcat((char *) buf1->name, "/");
tomoyo_fill_path_info(buf1);
}
if (!buf2->is_dir) {
strcat((char *) buf2->name, "/");
tomoyo_fill_path_info(buf2);
}
tomoyo_add_slash(&buf1);
tomoyo_add_slash(&buf2);
}
}
do {
error = tomoyo_path2_acl(&r, operation, buf1, buf2);
error = tomoyo_path2_acl(&r, operation, &buf1, &buf2);
if (!error)
break;
msg = tomoyo_path22keyword(operation);
tomoyo_warn_log(&r, "%s %s %s", msg, buf1->name, buf2->name);
tomoyo_warn_log(&r, "%s %s %s", msg, buf1.name, buf2.name);
error = tomoyo_supervisor(&r, "allow_%s %s %s\n", msg,
tomoyo_file_pattern(buf1),
tomoyo_file_pattern(buf2));
tomoyo_file_pattern(&buf1),
tomoyo_file_pattern(&buf2));
} while (error == TOMOYO_RETRY_REQUEST);
out:
kfree(buf1);
kfree(buf2);
kfree(buf1.name);
kfree(buf2.name);
tomoyo_read_unlock(idx);
if (r.mode != TOMOYO_CONFIG_ENFORCING)
error = 0;
......
......@@ -153,7 +153,6 @@ void __init tomoyo_mm_init(void)
{
int idx;
BUILD_BUG_ON(TOMOYO_MAX_PATHNAME_LEN > PATH_MAX);
for (idx = 0; idx < TOMOYO_MAX_HASH; idx++)
INIT_LIST_HEAD(&tomoyo_name_list[idx]);
INIT_LIST_HEAD(&tomoyo_kernel_domain.acl_info_list);
......
......@@ -24,57 +24,6 @@
/* Allow to call 'mount --make-shared /dir' */
#define TOMOYO_MOUNT_MAKE_SHARED_KEYWORD "--make-shared"
/**
* tomoyo_encode2: Encode binary string to ascii string.
*
* @str: String in binary format.
*
* Returns pointer to @str in ascii format on success, NULL otherwise.
*
* This function uses kzalloc(), so caller must kfree() if this function
* didn't return NULL.
*/
static char *tomoyo_encode2(const char *str)
{
int len = 0;
const char *p = str;
char *cp;
char *cp0;
if (!p)
return NULL;
while (*p) {
const unsigned char c = *p++;
if (c == '\\')
len += 2;
else if (c > ' ' && c < 127)
len++;
else
len += 4;
}
len++;
/* Reserve space for appending "/". */
cp = kzalloc(len + 10, GFP_NOFS);
if (!cp)
return NULL;
cp0 = cp;
p = str;
while (*p) {
const unsigned char c = *p++;
if (c == '\\') {
*cp++ = '\\';
*cp++ = '\\';
} else if (c > ' ' && c < 127) {
*cp++ = c;
} else {
*cp++ = '\\';
*cp++ = (c >> 6) + '0';
*cp++ = ((c >> 3) & 7) + '0';
*cp++ = (c & 7) + '0';
}
}
return cp0;
}
/**
* tomoyo_mount_acl2 - Check permission for mount() operation.
*
......@@ -104,7 +53,7 @@ static int tomoyo_mount_acl2(struct tomoyo_request_info *r, char *dev_name,
int error = -ENOMEM;
/* Get fstype. */
requested_type = tomoyo_encode2(type);
requested_type = tomoyo_encode(type);
if (!requested_type)
goto out;
rtype.name = requested_type;
......@@ -155,7 +104,7 @@ static int tomoyo_mount_acl2(struct tomoyo_request_info *r, char *dev_name,
/* Map dev_name to "<NULL>" if no dev_name given. */
if (!dev_name)
dev_name = "<NULL>";
requested_dev_name = tomoyo_encode2(dev_name);
requested_dev_name = tomoyo_encode(dev_name);
if (!requested_dev_name) {
error = -ENOMEM;
goto out;
......
......@@ -12,141 +12,153 @@
#include <linux/fs_struct.h>
#include <linux/magic.h>
#include <linux/slab.h>
#include <net/sock.h>
#include "common.h"
/**
* tomoyo_encode: Convert binary string to ascii string.
*
* @buffer: Buffer for ASCII string.
* @buflen: Size of @buffer.
* @str: Binary string.
* @str: String in binary format.
*
* Returns 0 on success, -ENOMEM otherwise.
* Returns pointer to @str in ascii format on success, NULL otherwise.
*
* This function uses kzalloc(), so caller must kfree() if this function
* didn't return NULL.
*/
int tomoyo_encode(char *buffer, int buflen, const char *str)
char *tomoyo_encode(const char *str)
{
while (1) {
const unsigned char c = *(unsigned char *) str++;
int len = 0;
const char *p = str;
char *cp;
char *cp0;
if (tomoyo_is_valid(c)) {
if (--buflen <= 0)
break;
*buffer++ = (char) c;
if (c != '\\')
continue;
if (--buflen <= 0)
break;
*buffer++ = (char) c;
continue;
}
if (!c) {
if (--buflen <= 0)
break;
*buffer = '\0';
return 0;
if (!p)
return NULL;
while (*p) {
const unsigned char c = *p++;
if (c == '\\')
len += 2;
else if (c > ' ' && c < 127)
len++;
else
len += 4;
}
len++;
/* Reserve space for appending "/". */
cp = kzalloc(len + 10, GFP_NOFS);
if (!cp)
return NULL;
cp0 = cp;
p = str;
while (*p) {
const unsigned char c = *p++;
if (c == '\\') {
*cp++ = '\\';
*cp++ = '\\';
} else if (c > ' ' && c < 127) {
*cp++ = c;
} else {
*cp++ = '\\';
*cp++ = (c >> 6) + '0';
*cp++ = ((c >> 3) & 7) + '0';
*cp++ = (c & 7) + '0';
}
buflen -= 4;
if (buflen <= 0)
break;
*buffer++ = '\\';
*buffer++ = (c >> 6) + '0';
*buffer++ = ((c >> 3) & 7) + '0';
*buffer++ = (c & 7) + '0';
}
return -ENOMEM;
return cp0;
}
/**
* tomoyo_realpath_from_path2 - Returns realpath(3) of the given dentry but ignores chroot'ed root.
* tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root.
*
* @path: Pointer to "struct path".
* @newname: Pointer to buffer to return value in.
* @newname_len: Size of @newname.
* @path: Pointer to "struct path".
*
* Returns 0 on success, negative value otherwise.
* Returns the realpath of the given @path on success, NULL otherwise.
*
* If dentry is a directory, trailing '/' is appended.
* Characters out of 0x20 < c < 0x7F range are converted to
* \ooo style octal string.
* Character \ is converted to \\ string.
*
* These functions use kzalloc(), so the caller must call kfree()
* if these functions didn't return NULL.
*/
int tomoyo_realpath_from_path2(struct path *path, char *newname,
int newname_len)
char *tomoyo_realpath_from_path(struct path *path)
{
int error = -ENOMEM;
char *buf = NULL;
char *name = NULL;
unsigned int buf_len = PAGE_SIZE / 2;
struct dentry *dentry = path->dentry;
char *sp;
if (!dentry || !path->mnt || !newname || newname_len <= 2048)
return -EINVAL;
if (dentry->d_op && dentry->d_op->d_dname) {
bool is_dir;
if (!dentry)
return NULL;