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wifi: cfg80211: allow cfg80211_defragment_element() without output 

If we just want to determine the length of the fragmented
data, we basically need the same logic, and really we want
it to be _literally_ the same logic, so it cannot be out
of sync in any way.

Allow calling cfg80211_defragment_element() without an output
buffer, where it then just returns the required output size.

Also add this to the tests, just to exercise it, using the
pre-calculated length to really do the defragmentation, which
checks that this is sufficient.

Reviewed-by: Miriam Rachel Korenblit <miriam.rachel.korenblit@intel.com>
Reviewed-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://msgid.link/20240228095718.6d6565b9e3f2.Ib441903f4b8644ba04b1c766f90580ee6f54fc66@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Johannes Berg 2024-02-28 09:55:42 +01:00
parent 22667035e5
commit 8ade3356b2
3 changed files with 45 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/net/cfg80211.h
View File

@ -6908,8 +6908,8 @@ bool cfg80211_iter_rnr(const u8 *elems, size_t elems_len,
* @elem: the element to defragment
* @ies: elements where @elem is contained
* @ieslen: length of @ies
* @data: buffer to store element data
* @data_len: length of @data
* @data: buffer to store element data, or %NULL to just determine size
* @data_len: length of @data, or 0
* @frag_id: the element ID of fragments
*
* Return: length of @data, or -EINVAL on error

27
net/wireless/scan.c
View File

@ -2504,16 +2504,22 @@ ssize_t cfg80211_defragment_element(const struct element *elem, const u8 *ies,
if (elem->id == WLAN_EID_EXTENSION) {
copied = elem->datalen - 1;
if (copied > data_len)
return -ENOSPC;
memmove(data, elem->data + 1, copied);
if (data) {
if (copied > data_len)
return -ENOSPC;
memmove(data, elem->data + 1, copied);
}
} else {
copied = elem->datalen;
if (copied > data_len)
return -ENOSPC;
memmove(data, elem->data, copied);
if (data) {
if (copied > data_len)
return -ENOSPC;
memmove(data, elem->data, copied);
}
}
/* Fragmented elements must have 255 bytes */
@ -2532,10 +2538,13 @@ ssize_t cfg80211_defragment_element(const struct element *elem, const u8 *ies,
elem_datalen = elem->datalen;
if (copied + elem_datalen > data_len)
return -ENOSPC;
if (data) {
if (copied + elem_datalen > data_len)
return -ENOSPC;
memmove(data + copied, elem->data, elem_datalen);
}
memmove(data + copied, elem->data, elem_datalen);
copied += elem_datalen;
/* Only the last fragment may be short */

30
net/wireless/tests/fragmentation.c
View File

@ -2,7 +2,7 @@
/*
* KUnit tests for element fragmentation
*
* Copyright (C) 2023 Intel Corporation
* Copyright (C) 2023-2024 Intel Corporation
*/
#include <linux/ieee80211.h>
#include <net/cfg80211.h>
@ -27,7 +27,12 @@ static void defragment_0(struct kunit *test)
ret = cfg80211_defragment_element((void *)input,
input, sizeof(input),
data, sizeof(input),
NULL, 0,
WLAN_EID_FRAGMENT);
KUNIT_EXPECT_EQ(test, ret, 253);
ret = cfg80211_defragment_element((void *)input,
input, sizeof(input),
data, ret,
WLAN_EID_FRAGMENT);
KUNIT_EXPECT_EQ(test, ret, 253);
KUNIT_EXPECT_MEMEQ(test, data, input + 3, 253);
@ -63,7 +68,12 @@ static void defragment_1(struct kunit *test)
ret = cfg80211_defragment_element((void *)input,
input, sizeof(input),
data, sizeof(input),
NULL, 0,
WLAN_EID_FRAGMENT);
KUNIT_EXPECT_EQ(test, ret, 254 + 7);
ret = cfg80211_defragment_element((void *)input,
input, sizeof(input),
data, ret,
WLAN_EID_FRAGMENT);
/* this means the last fragment was not used */
KUNIT_EXPECT_EQ(test, ret, 254 + 7);
@ -106,10 +116,15 @@ static void defragment_2(struct kunit *test)
ret = cfg80211_defragment_element((void *)input,
input, sizeof(input),
data, sizeof(input),
NULL, 0,
WLAN_EID_FRAGMENT);
/* this means the last fragment was not used */
KUNIT_EXPECT_EQ(test, ret, 254 + 255 + 1);
ret = cfg80211_defragment_element((void *)input,
input, sizeof(input),
data, ret,
WLAN_EID_FRAGMENT);
KUNIT_EXPECT_EQ(test, ret, 254 + 255 + 1);
KUNIT_EXPECT_MEMEQ(test, data, input + 3, 254);
KUNIT_EXPECT_MEMEQ(test, data + 254, input + 257 + 2, 255);
KUNIT_EXPECT_MEMEQ(test, data + 254 + 255, input + 2 * 257 + 2, 1);
@ -134,7 +149,12 @@ static void defragment_at_end(struct kunit *test)
ret = cfg80211_defragment_element((void *)input,
input, sizeof(input),
data, sizeof(input),
NULL, 0,
WLAN_EID_FRAGMENT);
KUNIT_EXPECT_EQ(test, ret, 254 + 7);
ret = cfg80211_defragment_element((void *)input,
input, sizeof(input),
data, ret,
WLAN_EID_FRAGMENT);
KUNIT_EXPECT_EQ(test, ret, 254 + 7);
KUNIT_EXPECT_MEMEQ(test, data, input + 3, 254);