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authorAndrey Ignatov <rdna@fb.com>2019-02-27 13:28:48 -0800
committerAlexei Starovoitov <ast@kernel.org>2019-04-12 13:54:58 -0700
commit808649fb787d918a48a360a668ee4ee9023f0c11 (patch)
treea58fb657373b8886c6ddf715476f62484edc233d /kernel/bpf
parent7b146cebe30cb481b0f70d85779da938da818637 (diff)
downloadlinux-808649fb787d918a48a360a668ee4ee9023f0c11.tar.bz2
bpf: Introduce bpf_sysctl_get_name helper
Add bpf_sysctl_get_name() helper to copy sysctl name (/proc/sys/ entry) into provided by BPF_PROG_TYPE_CGROUP_SYSCTL program buffer. By default full name (w/o /proc/sys/) is copied, e.g. "net/ipv4/tcp_mem". If BPF_F_SYSCTL_BASE_NAME flag is set, only base name will be copied, e.g. "tcp_mem". Documentation for the new helper is provided in bpf.h UAPI. Signed-off-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/cgroup.c70
1 files changed, 69 insertions, 1 deletions
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 610491b5f0aa..a68387043244 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -14,6 +14,7 @@
#include <linux/filter.h>
#include <linux/slab.h>
#include <linux/sysctl.h>
+#include <linux/string.h>
#include <linux/bpf.h>
#include <linux/bpf-cgroup.h>
#include <net/sock.h>
@@ -806,10 +807,77 @@ int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sysctl);
+static ssize_t sysctl_cpy_dir(const struct ctl_dir *dir, char **bufp,
+ size_t *lenp)
+{
+ ssize_t tmp_ret = 0, ret;
+
+ if (dir->header.parent) {
+ tmp_ret = sysctl_cpy_dir(dir->header.parent, bufp, lenp);
+ if (tmp_ret < 0)
+ return tmp_ret;
+ }
+
+ ret = strscpy(*bufp, dir->header.ctl_table[0].procname, *lenp);
+ if (ret < 0)
+ return ret;
+ *bufp += ret;
+ *lenp -= ret;
+ ret += tmp_ret;
+
+ /* Avoid leading slash. */
+ if (!ret)
+ return ret;
+
+ tmp_ret = strscpy(*bufp, "/", *lenp);
+ if (tmp_ret < 0)
+ return tmp_ret;
+ *bufp += tmp_ret;
+ *lenp -= tmp_ret;
+
+ return ret + tmp_ret;
+}
+
+BPF_CALL_4(bpf_sysctl_get_name, struct bpf_sysctl_kern *, ctx, char *, buf,
+ size_t, buf_len, u64, flags)
+{
+ ssize_t tmp_ret = 0, ret;
+
+ if (!buf)
+ return -EINVAL;
+
+ if (!(flags & BPF_F_SYSCTL_BASE_NAME)) {
+ if (!ctx->head)
+ return -EINVAL;
+ tmp_ret = sysctl_cpy_dir(ctx->head->parent, &buf, &buf_len);
+ if (tmp_ret < 0)
+ return tmp_ret;
+ }
+
+ ret = strscpy(buf, ctx->table->procname, buf_len);
+
+ return ret < 0 ? ret : tmp_ret + ret;
+}
+
+static const struct bpf_func_proto bpf_sysctl_get_name_proto = {
+ .func = bpf_sysctl_get_name,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_PTR_TO_MEM,
+ .arg3_type = ARG_CONST_SIZE,
+ .arg4_type = ARG_ANYTHING,
+};
+
static const struct bpf_func_proto *
sysctl_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
- return cgroup_base_func_proto(func_id, prog);
+ switch (func_id) {
+ case BPF_FUNC_sysctl_get_name:
+ return &bpf_sysctl_get_name_proto;
+ default:
+ return cgroup_base_func_proto(func_id, prog);
+ }
}
static bool sysctl_is_valid_access(int off, int size, enum bpf_access_type type,