bpf: Introduce bpf_sysctl_{get,set}_new_value helpers
Add helpers to work with new value being written to sysctl by user
space.
bpf_sysctl_get_new_value() copies value being written to sysctl into
provided buffer.
bpf_sysctl_set_new_value() overrides new value being written by user
space with a one from provided buffer. Buffer should contain string
representation of the value, similar to what can be seen in /proc/sys/.
Both helpers can be used only on sysctl write.
File position matters and can be managed by an interface that will be
introduced separately. E.g. if user space calls sys_write to a file in
/proc/sys/ at file position = X, where X > 0, then the value set by
bpf_sysctl_set_new_value() will be written starting from X. If program
wants to override whole value with specified buffer, file position has
to be set to zero.
Documentation for the new helpers is provided in bpf.h UAPI.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index b1c45da..1e97271 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -113,7 +113,8 @@
int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
struct ctl_table *table, int write,
- enum bpf_attach_type type);
+ void __user *buf, size_t *pcount,
+ void **new_buf, enum bpf_attach_type type);
static inline enum bpf_cgroup_storage_type cgroup_storage_type(
struct bpf_map *map)
@@ -261,11 +262,12 @@
})
-#define BPF_CGROUP_RUN_PROG_SYSCTL(head, table, write) \
+#define BPF_CGROUP_RUN_PROG_SYSCTL(head, table, write, buf, count, nbuf) \
({ \
int __ret = 0; \
if (cgroup_bpf_enabled) \
__ret = __cgroup_bpf_run_filter_sysctl(head, table, write, \
+ buf, count, nbuf, \
BPF_CGROUP_SYSCTL); \
__ret; \
})
@@ -338,7 +340,7 @@
#define BPF_CGROUP_RUN_PROG_UDP6_SENDMSG_LOCK(sk, uaddr, t_ctx) ({ 0; })
#define BPF_CGROUP_RUN_PROG_SOCK_OPS(sock_ops) ({ 0; })
#define BPF_CGROUP_RUN_PROG_DEVICE_CGROUP(type,major,minor,access) ({ 0; })
-#define BPF_CGROUP_RUN_PROG_SYSCTL(head, table, write) ({ 0; })
+#define BPF_CGROUP_RUN_PROG_SYSCTL(head,table,write,buf,count,nbuf) ({ 0; })
#define for_each_cgroup_storage_type(stype) for (; false; )