From e5cc852b5bfb576a875fbba49f5ed4d0e6a85be9 Mon Sep 17 00:00:00 2001 From: Zijian Zhang Date: Tue, 11 Mar 2025 08:51:19 +0900 Subject: [PATCH] bpf, sockmap: Several fixes to bpf_msg_push_data BugLink: https://bugs.launchpad.net/bugs/2101915 [ Upstream commit 15ab0548e3107665c34579ae523b2b6e7c22082a ] 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: 6fff607e2f14 ("bpf: sk_msg program helper bpf_msg_push_data") Signed-off-by: Zijian Zhang Link: https://lore.kernel.org/r/20241106222520.527076-7-zijianzhang@bytedance.com Signed-off-by: Martin KaFai Lau Signed-off-by: Sasha Levin Signed-off-by: Koichiro Den Signed-off-by: Stefan Bader --- net/core/filter.c | 53 +++++++++++++++++++++++++++++------------------ 1 file changed, 33 insertions(+), 20 deletions(-) diff --git a/net/core/filter.c b/net/core/filter.c index 0c548a302f13..3f40c6bc656a 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2790,7 +2790,7 @@ 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); @@ -2815,6 +2815,8 @@ 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; @@ -2831,7 +2833,13 @@ 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); @@ -2842,39 +2850,44 @@ 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;