summaryrefslogtreecommitdiff
path: root/kernel
diff options
context:
space:
mode:
authorJiri Olsa <jolsa@kernel.org>2022-06-15 14:21:17 +0300
committerAlexei Starovoitov <ast@kernel.org>2022-06-17 05:42:21 +0300
commiteb5fb0325698d05f0bf78d322de82c451a3685a2 (patch)
treec0f26fc64a8678d3317c0d88c55f1aa1e746afcc /kernel
parenteb1b2985fe5c5f02e43e4c0d47bbe7ed835007f3 (diff)
downloadlinux-eb5fb0325698d05f0bf78d322de82c451a3685a2.tar.xz
bpf: Force cookies array to follow symbols sorting
When user specifies symbols and cookies for kprobe_multi link interface it's very likely the cookies will be misplaced and returned to wrong functions (via get_attach_cookie helper). The reason is that to resolve the provided functions we sort them before passing them to ftrace_lookup_symbols, but we do not do the same sort on the cookie values. Fixing this by using sort_r function with custom swap callback that swaps cookie values as well. Fixes: 0236fec57a15 ("bpf: Resolve symbols with ftrace_lookup_symbols for kprobe multi link") Signed-off-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/r/20220615112118.497303-4-jolsa@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/bpf_trace.c60
1 files changed, 45 insertions, 15 deletions
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 7a13e6ac6327..88589d74a892 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2423,7 +2423,7 @@ kprobe_multi_link_handler(struct fprobe *fp, unsigned long entry_ip,
kprobe_multi_link_prog_run(link, entry_ip, regs);
}
-static int symbols_cmp(const void *a, const void *b)
+static int symbols_cmp_r(const void *a, const void *b, const void *priv)
{
const char **str_a = (const char **) a;
const char **str_b = (const char **) b;
@@ -2431,6 +2431,28 @@ static int symbols_cmp(const void *a, const void *b)
return strcmp(*str_a, *str_b);
}
+struct multi_symbols_sort {
+ const char **funcs;
+ u64 *cookies;
+};
+
+static void symbols_swap_r(void *a, void *b, int size, const void *priv)
+{
+ const struct multi_symbols_sort *data = priv;
+ const char **name_a = a, **name_b = b;
+
+ swap(*name_a, *name_b);
+
+ /* If defined, swap also related cookies. */
+ if (data->cookies) {
+ u64 *cookie_a, *cookie_b;
+
+ cookie_a = data->cookies + (name_a - data->funcs);
+ cookie_b = data->cookies + (name_b - data->funcs);
+ swap(*cookie_a, *cookie_b);
+ }
+}
+
int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
{
struct bpf_kprobe_multi_link *link = NULL;
@@ -2468,38 +2490,46 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
if (!addrs)
return -ENOMEM;
+ ucookies = u64_to_user_ptr(attr->link_create.kprobe_multi.cookies);
+ if (ucookies) {
+ cookies = kvmalloc_array(cnt, sizeof(*addrs), GFP_KERNEL);
+ if (!cookies) {
+ err = -ENOMEM;
+ goto error;
+ }
+ if (copy_from_user(cookies, ucookies, size)) {
+ err = -EFAULT;
+ goto error;
+ }
+ }
+
if (uaddrs) {
if (copy_from_user(addrs, uaddrs, size)) {
err = -EFAULT;
goto error;
}
} else {
+ struct multi_symbols_sort data = {
+ .cookies = cookies,
+ };
struct user_syms us;
err = copy_user_syms(&us, usyms, cnt);
if (err)
goto error;
- sort(us.syms, cnt, sizeof(*us.syms), symbols_cmp, NULL);
+ if (cookies)
+ data.funcs = us.syms;
+
+ sort_r(us.syms, cnt, sizeof(*us.syms), symbols_cmp_r,
+ symbols_swap_r, &data);
+
err = ftrace_lookup_symbols(us.syms, cnt, addrs);
free_user_syms(&us);
if (err)
goto error;
}
- ucookies = u64_to_user_ptr(attr->link_create.kprobe_multi.cookies);
- if (ucookies) {
- cookies = kvmalloc_array(cnt, sizeof(*addrs), GFP_KERNEL);
- if (!cookies) {
- err = -ENOMEM;
- goto error;
- }
- if (copy_from_user(cookies, ucookies, size)) {
- err = -EFAULT;
- goto error;
- }
- }
-
link = kzalloc(sizeof(*link), GFP_KERNEL);
if (!link) {
err = -ENOMEM;