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bpf, sockmap: Several fixes to bpf_msg_push_data

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[ Upstream commit 15ab0548e3 ]

Several fixes to bpf_msg_push_data,
1. test_sockmap has tests where bpf_msg_push_data is invoked to push some
data at the end of a message, but -EINVAL is returned. In this case, in
bpf_msg_push_data, after the first loop, i will be set to msg->sg.end, add
the logic to handle it.
2. In the code block of "if (start - offset)", it's possible that "i"
points to the last of sk_msg_elem. In this case, "sk_msg_iter_next(msg,
end)" might still be called twice, another invoking is in "if (!copy)"
code block, but actually only one is needed. Add the logic to handle it,
and reconstruct the code to make the logic more clear.

Fixes: 6fff607e2f ("bpf: sk_msg program helper bpf_msg_push_data")
Signed-off-by: Zijian Zhang <zijianzhang@bytedance.com>
Link: https://lore.kernel.org/r/20241106222520.527076-7-zijianzhang@bytedance.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Zijian Zhang
2024-11-06 22:25:18 +00:00
committed by Greg Kroah-Hartman
parent 7073d9004f
commit 0f8db9b369
1 changed files with 33 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files
net/core/filter.c
+33 -20
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@@ -2757,7 +2757,7 @@ BPF_CALL_4(bpf_msg_push_data, struct sk_msg *, msg, u32, start,
sk_msg_iter_var_next(i);
} while (i != msg->sg.end);
if (start >= offset + l)
if (start > offset + l)
return -EINVAL;
space = MAX_MSG_FRAGS - sk_msg_elem_used(msg);
@@ -2782,6 +2782,8 @@ BPF_CALL_4(bpf_msg_push_data, struct sk_msg *, msg, u32, start,
raw = page_address(page);
if (i == msg->sg.end)
sk_msg_iter_var_prev(i);
psge = sk_msg_elem(msg, i);
front = start - offset;
back = psge->length - front;
@@ -2798,7 +2800,13 @@ BPF_CALL_4(bpf_msg_push_data, struct sk_msg *, msg, u32, start,
}
put_page(sg_page(psge));
} else if (start - offset) {
new = i;
goto place_new;
}
if (start - offset) {
if (i == msg->sg.end)
sk_msg_iter_var_prev(i);
psge = sk_msg_elem(msg, i);
rsge = sk_msg_elem_cpy(msg, i);
@@ -2809,39 +2817,44 @@ BPF_CALL_4(bpf_msg_push_data, struct sk_msg *, msg, u32, start,
sk_msg_iter_var_next(i);
sg_unmark_end(psge);
sg_unmark_end(&rsge);
sk_msg_iter_next(msg, end);
}
/* Slot(s) to place newly allocated data */
sk_msg_iter_next(msg, end);
new = i;
sk_msg_iter_var_next(i);
if (i == msg->sg.end) {
if (!rsge.length)
goto place_new;
sk_msg_iter_next(msg, end);
goto place_new;
}
/* Shift one or two slots as needed */
if (!copy) {
sge = sk_msg_elem_cpy(msg, i);
sge = sk_msg_elem_cpy(msg, new);
sg_unmark_end(&sge);
nsge = sk_msg_elem_cpy(msg, i);
if (rsge.length) {
sk_msg_iter_var_next(i);
sg_unmark_end(&sge);
nnsge = sk_msg_elem_cpy(msg, i);
sk_msg_iter_next(msg, end);
}
nsge = sk_msg_elem_cpy(msg, i);
while (i != msg->sg.end) {
msg->sg.data[i] = sge;
sge = nsge;
sk_msg_iter_var_next(i);
if (rsge.length) {
sk_msg_iter_var_next(i);
nsge = nnsge;
nnsge = sk_msg_elem_cpy(msg, i);
}
while (i != msg->sg.end) {
msg->sg.data[i] = sge;
sge = nsge;
sk_msg_iter_var_next(i);
if (rsge.length) {
nsge = nnsge;
nnsge = sk_msg_elem_cpy(msg, i);
} else {
nsge = sk_msg_elem_cpy(msg, i);
}
} else {
nsge = sk_msg_elem_cpy(msg, i);
}
}
place_new:
/* Place newly allocated data buffer */
sk_mem_charge(msg->sk, len);
msg->sg.size += len;