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edfa9af0a7
Improve consistency for bpf_mprog_query() API and let the latter also handle a NULL entry as can be the case for tcx. Instead of returning -ENOENT, we copy a count of 0 and revision of 1 to user space, so that this can be fed into a subsequent bpf_mprog_attach() call as expected_revision. A BPF self- test as part of this series has been added to assert this case. Suggested-by: Lorenz Bauer <lmb@isovalent.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/r/20231006220655.1653-2-daniel@iogearbox.net Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
452 lines
12 KiB
C
452 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2023 Isovalent */
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#include <linux/bpf.h>
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#include <linux/bpf_mprog.h>
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static int bpf_mprog_link(struct bpf_tuple *tuple,
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u32 id_or_fd, u32 flags,
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enum bpf_prog_type type)
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{
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struct bpf_link *link = ERR_PTR(-EINVAL);
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bool id = flags & BPF_F_ID;
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if (id)
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link = bpf_link_by_id(id_or_fd);
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else if (id_or_fd)
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link = bpf_link_get_from_fd(id_or_fd);
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if (IS_ERR(link))
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return PTR_ERR(link);
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if (type && link->prog->type != type) {
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bpf_link_put(link);
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return -EINVAL;
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}
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tuple->link = link;
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tuple->prog = link->prog;
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return 0;
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}
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static int bpf_mprog_prog(struct bpf_tuple *tuple,
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u32 id_or_fd, u32 flags,
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enum bpf_prog_type type)
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{
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struct bpf_prog *prog = ERR_PTR(-EINVAL);
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bool id = flags & BPF_F_ID;
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if (id)
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prog = bpf_prog_by_id(id_or_fd);
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else if (id_or_fd)
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prog = bpf_prog_get(id_or_fd);
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if (IS_ERR(prog))
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return PTR_ERR(prog);
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if (type && prog->type != type) {
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bpf_prog_put(prog);
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return -EINVAL;
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}
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tuple->link = NULL;
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tuple->prog = prog;
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return 0;
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}
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static int bpf_mprog_tuple_relative(struct bpf_tuple *tuple,
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u32 id_or_fd, u32 flags,
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enum bpf_prog_type type)
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{
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bool link = flags & BPF_F_LINK;
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bool id = flags & BPF_F_ID;
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memset(tuple, 0, sizeof(*tuple));
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if (link)
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return bpf_mprog_link(tuple, id_or_fd, flags, type);
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/* If no relevant flag is set and no id_or_fd was passed, then
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* tuple link/prog is just NULLed. This is the case when before/
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* after selects first/last position without passing fd.
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*/
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if (!id && !id_or_fd)
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return 0;
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return bpf_mprog_prog(tuple, id_or_fd, flags, type);
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}
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static void bpf_mprog_tuple_put(struct bpf_tuple *tuple)
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{
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if (tuple->link)
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bpf_link_put(tuple->link);
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else if (tuple->prog)
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bpf_prog_put(tuple->prog);
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}
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/* The bpf_mprog_{replace,delete}() operate on exact idx position with the
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* one exception that for deletion we support delete from front/back. In
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* case of front idx is -1, in case of back idx is bpf_mprog_total(entry).
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* Adjustment to first and last entry is trivial. The bpf_mprog_insert()
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* we have to deal with the following cases:
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*
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* idx + before:
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*
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* Insert P4 before P3: idx for old array is 1, idx for new array is 2,
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* hence we adjust target idx for the new array, so that memmove copies
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* P1 and P2 to the new entry, and we insert P4 into idx 2. Inserting
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* before P1 would have old idx -1 and new idx 0.
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*
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* +--+--+--+ +--+--+--+--+ +--+--+--+--+
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* |P1|P2|P3| ==> |P1|P2| |P3| ==> |P1|P2|P4|P3|
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* +--+--+--+ +--+--+--+--+ +--+--+--+--+
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*
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* idx + after:
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*
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* Insert P4 after P2: idx for old array is 2, idx for new array is 2.
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* Again, memmove copies P1 and P2 to the new entry, and we insert P4
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* into idx 2. Inserting after P3 would have both old/new idx at 4 aka
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* bpf_mprog_total(entry).
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*
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* +--+--+--+ +--+--+--+--+ +--+--+--+--+
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* |P1|P2|P3| ==> |P1|P2| |P3| ==> |P1|P2|P4|P3|
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* +--+--+--+ +--+--+--+--+ +--+--+--+--+
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*/
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static int bpf_mprog_replace(struct bpf_mprog_entry *entry,
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struct bpf_mprog_entry **entry_new,
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struct bpf_tuple *ntuple, int idx)
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{
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struct bpf_mprog_fp *fp;
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struct bpf_mprog_cp *cp;
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struct bpf_prog *oprog;
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bpf_mprog_read(entry, idx, &fp, &cp);
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oprog = READ_ONCE(fp->prog);
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bpf_mprog_write(fp, cp, ntuple);
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if (!ntuple->link) {
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WARN_ON_ONCE(cp->link);
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bpf_prog_put(oprog);
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}
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*entry_new = entry;
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return 0;
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}
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static int bpf_mprog_insert(struct bpf_mprog_entry *entry,
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struct bpf_mprog_entry **entry_new,
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struct bpf_tuple *ntuple, int idx, u32 flags)
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{
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int total = bpf_mprog_total(entry);
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struct bpf_mprog_entry *peer;
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struct bpf_mprog_fp *fp;
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struct bpf_mprog_cp *cp;
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peer = bpf_mprog_peer(entry);
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bpf_mprog_entry_copy(peer, entry);
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if (idx == total)
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goto insert;
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else if (flags & BPF_F_BEFORE)
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idx += 1;
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bpf_mprog_entry_grow(peer, idx);
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insert:
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bpf_mprog_read(peer, idx, &fp, &cp);
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bpf_mprog_write(fp, cp, ntuple);
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bpf_mprog_inc(peer);
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*entry_new = peer;
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return 0;
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}
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static int bpf_mprog_delete(struct bpf_mprog_entry *entry,
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struct bpf_mprog_entry **entry_new,
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struct bpf_tuple *dtuple, int idx)
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{
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int total = bpf_mprog_total(entry);
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struct bpf_mprog_entry *peer;
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peer = bpf_mprog_peer(entry);
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bpf_mprog_entry_copy(peer, entry);
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if (idx == -1)
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idx = 0;
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else if (idx == total)
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idx = total - 1;
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bpf_mprog_entry_shrink(peer, idx);
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bpf_mprog_dec(peer);
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bpf_mprog_mark_for_release(peer, dtuple);
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*entry_new = peer;
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return 0;
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}
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/* In bpf_mprog_pos_*() we evaluate the target position for the BPF
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* program/link that needs to be replaced, inserted or deleted for
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* each "rule" independently. If all rules agree on that position
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* or existing element, then enact replacement, addition or deletion.
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* If this is not the case, then the request cannot be satisfied and
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* we bail out with an error.
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*/
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static int bpf_mprog_pos_exact(struct bpf_mprog_entry *entry,
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struct bpf_tuple *tuple)
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{
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struct bpf_mprog_fp *fp;
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struct bpf_mprog_cp *cp;
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int i;
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for (i = 0; i < bpf_mprog_total(entry); i++) {
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bpf_mprog_read(entry, i, &fp, &cp);
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if (tuple->prog == READ_ONCE(fp->prog))
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return tuple->link == cp->link ? i : -EBUSY;
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}
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return -ENOENT;
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}
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static int bpf_mprog_pos_before(struct bpf_mprog_entry *entry,
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struct bpf_tuple *tuple)
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{
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struct bpf_mprog_fp *fp;
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struct bpf_mprog_cp *cp;
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int i;
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for (i = 0; i < bpf_mprog_total(entry); i++) {
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bpf_mprog_read(entry, i, &fp, &cp);
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if (tuple->prog == READ_ONCE(fp->prog) &&
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(!tuple->link || tuple->link == cp->link))
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return i - 1;
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}
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return tuple->prog ? -ENOENT : -1;
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}
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static int bpf_mprog_pos_after(struct bpf_mprog_entry *entry,
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struct bpf_tuple *tuple)
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{
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struct bpf_mprog_fp *fp;
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struct bpf_mprog_cp *cp;
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int i;
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for (i = 0; i < bpf_mprog_total(entry); i++) {
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bpf_mprog_read(entry, i, &fp, &cp);
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if (tuple->prog == READ_ONCE(fp->prog) &&
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(!tuple->link || tuple->link == cp->link))
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return i + 1;
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}
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return tuple->prog ? -ENOENT : bpf_mprog_total(entry);
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}
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int bpf_mprog_attach(struct bpf_mprog_entry *entry,
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struct bpf_mprog_entry **entry_new,
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struct bpf_prog *prog_new, struct bpf_link *link,
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struct bpf_prog *prog_old,
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u32 flags, u32 id_or_fd, u64 revision)
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{
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struct bpf_tuple rtuple, ntuple = {
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.prog = prog_new,
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.link = link,
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}, otuple = {
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.prog = prog_old,
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.link = link,
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};
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int ret, idx = -ERANGE, tidx;
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if (revision && revision != bpf_mprog_revision(entry))
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return -ESTALE;
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if (bpf_mprog_exists(entry, prog_new))
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return -EEXIST;
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ret = bpf_mprog_tuple_relative(&rtuple, id_or_fd,
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flags & ~BPF_F_REPLACE,
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prog_new->type);
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if (ret)
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return ret;
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if (flags & BPF_F_REPLACE) {
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tidx = bpf_mprog_pos_exact(entry, &otuple);
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if (tidx < 0) {
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ret = tidx;
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goto out;
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}
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idx = tidx;
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} else if (bpf_mprog_total(entry) == bpf_mprog_max()) {
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ret = -ERANGE;
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goto out;
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}
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if (flags & BPF_F_BEFORE) {
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tidx = bpf_mprog_pos_before(entry, &rtuple);
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if (tidx < -1 || (idx >= -1 && tidx != idx)) {
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ret = tidx < -1 ? tidx : -ERANGE;
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goto out;
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}
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idx = tidx;
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}
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if (flags & BPF_F_AFTER) {
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tidx = bpf_mprog_pos_after(entry, &rtuple);
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if (tidx < -1 || (idx >= -1 && tidx != idx)) {
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ret = tidx < 0 ? tidx : -ERANGE;
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goto out;
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}
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idx = tidx;
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}
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if (idx < -1) {
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if (rtuple.prog || flags) {
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ret = -EINVAL;
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goto out;
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}
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idx = bpf_mprog_total(entry);
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flags = BPF_F_AFTER;
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}
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if (idx >= bpf_mprog_max()) {
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ret = -ERANGE;
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goto out;
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}
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if (flags & BPF_F_REPLACE)
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ret = bpf_mprog_replace(entry, entry_new, &ntuple, idx);
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else
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ret = bpf_mprog_insert(entry, entry_new, &ntuple, idx, flags);
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out:
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bpf_mprog_tuple_put(&rtuple);
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return ret;
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}
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static int bpf_mprog_fetch(struct bpf_mprog_entry *entry,
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struct bpf_tuple *tuple, int idx)
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{
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int total = bpf_mprog_total(entry);
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struct bpf_mprog_cp *cp;
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struct bpf_mprog_fp *fp;
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struct bpf_prog *prog;
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struct bpf_link *link;
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if (idx == -1)
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idx = 0;
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else if (idx == total)
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idx = total - 1;
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bpf_mprog_read(entry, idx, &fp, &cp);
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prog = READ_ONCE(fp->prog);
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link = cp->link;
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/* The deletion request can either be without filled tuple in which
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* case it gets populated here based on idx, or with filled tuple
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* where the only thing we end up doing is the WARN_ON_ONCE() assert.
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* If we hit a BPF link at the given index, it must not be removed
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* from opts path.
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*/
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if (link && !tuple->link)
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return -EBUSY;
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WARN_ON_ONCE(tuple->prog && tuple->prog != prog);
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WARN_ON_ONCE(tuple->link && tuple->link != link);
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tuple->prog = prog;
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tuple->link = link;
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return 0;
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}
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int bpf_mprog_detach(struct bpf_mprog_entry *entry,
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struct bpf_mprog_entry **entry_new,
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struct bpf_prog *prog, struct bpf_link *link,
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u32 flags, u32 id_or_fd, u64 revision)
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{
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struct bpf_tuple rtuple, dtuple = {
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.prog = prog,
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.link = link,
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};
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int ret, idx = -ERANGE, tidx;
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if (flags & BPF_F_REPLACE)
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return -EINVAL;
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if (revision && revision != bpf_mprog_revision(entry))
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return -ESTALE;
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if (!bpf_mprog_total(entry))
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return -ENOENT;
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ret = bpf_mprog_tuple_relative(&rtuple, id_or_fd, flags,
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prog ? prog->type :
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BPF_PROG_TYPE_UNSPEC);
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if (ret)
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return ret;
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if (dtuple.prog) {
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tidx = bpf_mprog_pos_exact(entry, &dtuple);
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if (tidx < 0) {
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ret = tidx;
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goto out;
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}
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idx = tidx;
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}
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if (flags & BPF_F_BEFORE) {
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tidx = bpf_mprog_pos_before(entry, &rtuple);
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if (tidx < -1 || (idx >= -1 && tidx != idx)) {
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ret = tidx < -1 ? tidx : -ERANGE;
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goto out;
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}
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idx = tidx;
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}
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if (flags & BPF_F_AFTER) {
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tidx = bpf_mprog_pos_after(entry, &rtuple);
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if (tidx < -1 || (idx >= -1 && tidx != idx)) {
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ret = tidx < 0 ? tidx : -ERANGE;
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goto out;
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}
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idx = tidx;
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}
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if (idx < -1) {
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if (rtuple.prog || flags) {
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ret = -EINVAL;
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goto out;
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}
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idx = bpf_mprog_total(entry);
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flags = BPF_F_AFTER;
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}
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if (idx >= bpf_mprog_max()) {
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ret = -ERANGE;
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goto out;
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}
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ret = bpf_mprog_fetch(entry, &dtuple, idx);
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if (ret)
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goto out;
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ret = bpf_mprog_delete(entry, entry_new, &dtuple, idx);
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out:
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bpf_mprog_tuple_put(&rtuple);
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return ret;
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}
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int bpf_mprog_query(const union bpf_attr *attr, union bpf_attr __user *uattr,
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struct bpf_mprog_entry *entry)
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{
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u32 __user *uprog_flags, *ulink_flags;
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u32 __user *uprog_id, *ulink_id;
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struct bpf_mprog_fp *fp;
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struct bpf_mprog_cp *cp;
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struct bpf_prog *prog;
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const u32 flags = 0;
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u32 id, count = 0;
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u64 revision = 1;
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int i, ret = 0;
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if (attr->query.query_flags || attr->query.attach_flags)
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return -EINVAL;
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if (entry) {
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revision = bpf_mprog_revision(entry);
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count = bpf_mprog_total(entry);
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}
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if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
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return -EFAULT;
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if (copy_to_user(&uattr->query.revision, &revision, sizeof(revision)))
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return -EFAULT;
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if (copy_to_user(&uattr->query.count, &count, sizeof(count)))
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return -EFAULT;
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uprog_id = u64_to_user_ptr(attr->query.prog_ids);
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uprog_flags = u64_to_user_ptr(attr->query.prog_attach_flags);
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ulink_id = u64_to_user_ptr(attr->query.link_ids);
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ulink_flags = u64_to_user_ptr(attr->query.link_attach_flags);
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if (attr->query.count == 0 || !uprog_id || !count)
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return 0;
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if (attr->query.count < count) {
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count = attr->query.count;
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ret = -ENOSPC;
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}
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for (i = 0; i < bpf_mprog_max(); i++) {
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bpf_mprog_read(entry, i, &fp, &cp);
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prog = READ_ONCE(fp->prog);
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if (!prog)
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break;
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id = prog->aux->id;
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if (copy_to_user(uprog_id + i, &id, sizeof(id)))
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return -EFAULT;
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if (uprog_flags &&
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copy_to_user(uprog_flags + i, &flags, sizeof(flags)))
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return -EFAULT;
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id = cp->link ? cp->link->id : 0;
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if (ulink_id &&
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copy_to_user(ulink_id + i, &id, sizeof(id)))
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return -EFAULT;
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if (ulink_flags &&
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copy_to_user(ulink_flags + i, &flags, sizeof(flags)))
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return -EFAULT;
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if (i + 1 == count)
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break;
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}
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return ret;
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}
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