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-rw-r--r--fs/proc/proc_sysctl.c5
-rw-r--r--include/linux/bpf-cgroup.h18
-rw-r--r--include/linux/bpf_types.h1
-rw-r--r--include/linux/filter.h8
-rw-r--r--include/uapi/linux/bpf.h9
-rw-r--r--kernel/bpf/cgroup.c92
-rw-r--r--kernel/bpf/syscall.c7
-rw-r--r--kernel/bpf/verifier.c1
8 files changed, 141 insertions, 0 deletions
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index d65390727541..e01b02150340 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -13,6 +13,7 @@
#include <linux/namei.h>
#include <linux/mm.h>
#include <linux/module.h>
+#include <linux/bpf-cgroup.h>
#include "internal.h"
static const struct dentry_operations proc_sys_dentry_operations;
@@ -588,6 +589,10 @@ static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
if (!table->proc_handler)
goto out;
+ error = BPF_CGROUP_RUN_PROG_SYSCTL(head, table, write);
+ if (error)
+ goto out;
+
/* careful: calling conventions are nasty here */
res = count;
error = table->proc_handler(table, write, buf, &res, ppos);
diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index a4c644c1c091..b1c45da20a26 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -17,6 +17,8 @@ struct bpf_map;
struct bpf_prog;
struct bpf_sock_ops_kern;
struct bpf_cgroup_storage;
+struct ctl_table;
+struct ctl_table_header;
#ifdef CONFIG_CGROUP_BPF
@@ -109,6 +111,10 @@ int __cgroup_bpf_run_filter_sock_ops(struct sock *sk,
int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
short access, enum bpf_attach_type type);
+int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
+ struct ctl_table *table, int write,
+ enum bpf_attach_type type);
+
static inline enum bpf_cgroup_storage_type cgroup_storage_type(
struct bpf_map *map)
{
@@ -253,6 +259,17 @@ int bpf_percpu_cgroup_storage_update(struct bpf_map *map, void *key,
\
__ret; \
})
+
+
+#define BPF_CGROUP_RUN_PROG_SYSCTL(head, table, write) \
+({ \
+ int __ret = 0; \
+ if (cgroup_bpf_enabled) \
+ __ret = __cgroup_bpf_run_filter_sysctl(head, table, write, \
+ BPF_CGROUP_SYSCTL); \
+ __ret; \
+})
+
int cgroup_bpf_prog_attach(const union bpf_attr *attr,
enum bpf_prog_type ptype, struct bpf_prog *prog);
int cgroup_bpf_prog_detach(const union bpf_attr *attr,
@@ -321,6 +338,7 @@ static inline int bpf_percpu_cgroup_storage_update(struct bpf_map *map,
#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 for_each_cgroup_storage_type(stype) for (; false; )
diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
index 08bf2f1fe553..d26991a16894 100644
--- a/include/linux/bpf_types.h
+++ b/include/linux/bpf_types.h
@@ -28,6 +28,7 @@ BPF_PROG_TYPE(BPF_PROG_TYPE_RAW_TRACEPOINT, raw_tracepoint)
#endif
#ifdef CONFIG_CGROUP_BPF
BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_DEVICE, cg_dev)
+BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_SYSCTL, cg_sysctl)
#endif
#ifdef CONFIG_BPF_LIRC_MODE2
BPF_PROG_TYPE(BPF_PROG_TYPE_LIRC_MODE2, lirc_mode2)
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 6074aa064b54..a17732057880 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -33,6 +33,8 @@ struct bpf_prog_aux;
struct xdp_rxq_info;
struct xdp_buff;
struct sock_reuseport;
+struct ctl_table;
+struct ctl_table_header;
/* ArgX, context and stack frame pointer register positions. Note,
* Arg1, Arg2, Arg3, etc are used as argument mappings of function
@@ -1177,4 +1179,10 @@ struct bpf_sock_ops_kern {
*/
};
+struct bpf_sysctl_kern {
+ struct ctl_table_header *head;
+ struct ctl_table *table;
+ int write;
+};
+
#endif /* __LINUX_FILTER_H__ */
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 2e96d0b4bf65..cc2a2466d5f3 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -167,6 +167,7 @@ enum bpf_prog_type {
BPF_PROG_TYPE_LIRC_MODE2,
BPF_PROG_TYPE_SK_REUSEPORT,
BPF_PROG_TYPE_FLOW_DISSECTOR,
+ BPF_PROG_TYPE_CGROUP_SYSCTL,
};
enum bpf_attach_type {
@@ -188,6 +189,7 @@ enum bpf_attach_type {
BPF_CGROUP_UDP6_SENDMSG,
BPF_LIRC_MODE2,
BPF_FLOW_DISSECTOR,
+ BPF_CGROUP_SYSCTL,
__MAX_BPF_ATTACH_TYPE
};
@@ -3308,4 +3310,11 @@ struct bpf_line_info {
struct bpf_spin_lock {
__u32 val;
};
+
+struct bpf_sysctl {
+ __u32 write; /* Sysctl is being read (= 0) or written (= 1).
+ * Allows 1,2,4-byte read, but no write.
+ */
+};
+
#endif /* _UAPI__LINUX_BPF_H__ */
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index f6cd38746df2..610491b5f0aa 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -11,7 +11,9 @@
#include <linux/kernel.h>
#include <linux/atomic.h>
#include <linux/cgroup.h>
+#include <linux/filter.h>
#include <linux/slab.h>
+#include <linux/sysctl.h>
#include <linux/bpf.h>
#include <linux/bpf-cgroup.h>
#include <net/sock.h>
@@ -768,3 +770,93 @@ const struct bpf_verifier_ops cg_dev_verifier_ops = {
.get_func_proto = cgroup_dev_func_proto,
.is_valid_access = cgroup_dev_is_valid_access,
};
+
+/**
+ * __cgroup_bpf_run_filter_sysctl - Run a program on sysctl
+ *
+ * @head: sysctl table header
+ * @table: sysctl table
+ * @write: sysctl is being read (= 0) or written (= 1)
+ * @type: type of program to be executed
+ *
+ * Program is run when sysctl is being accessed, either read or written, and
+ * can allow or deny such access.
+ *
+ * This function will return %-EPERM if an attached program is found and
+ * returned value != 1 during execution. In all other cases 0 is returned.
+ */
+int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
+ struct ctl_table *table, int write,
+ enum bpf_attach_type type)
+{
+ struct bpf_sysctl_kern ctx = {
+ .head = head,
+ .table = table,
+ .write = write,
+ };
+ struct cgroup *cgrp;
+ int ret;
+
+ rcu_read_lock();
+ cgrp = task_dfl_cgroup(current);
+ ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], &ctx, BPF_PROG_RUN);
+ rcu_read_unlock();
+
+ return ret == 1 ? 0 : -EPERM;
+}
+EXPORT_SYMBOL(__cgroup_bpf_run_filter_sysctl);
+
+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);
+}
+
+static bool sysctl_is_valid_access(int off, int size, enum bpf_access_type type,
+ const struct bpf_prog *prog,
+ struct bpf_insn_access_aux *info)
+{
+ const int size_default = sizeof(__u32);
+
+ if (off < 0 || off + size > sizeof(struct bpf_sysctl) ||
+ off % size || type != BPF_READ)
+ return false;
+
+ switch (off) {
+ case offsetof(struct bpf_sysctl, write):
+ bpf_ctx_record_field_size(info, size_default);
+ return bpf_ctx_narrow_access_ok(off, size, size_default);
+ default:
+ return false;
+ }
+}
+
+static u32 sysctl_convert_ctx_access(enum bpf_access_type type,
+ const struct bpf_insn *si,
+ struct bpf_insn *insn_buf,
+ struct bpf_prog *prog, u32 *target_size)
+{
+ struct bpf_insn *insn = insn_buf;
+
+ switch (si->off) {
+ case offsetof(struct bpf_sysctl, write):
+ *insn++ = BPF_LDX_MEM(
+ BPF_SIZE(si->code), si->dst_reg, si->src_reg,
+ bpf_target_off(struct bpf_sysctl_kern, write,
+ FIELD_SIZEOF(struct bpf_sysctl_kern,
+ write),
+ target_size));
+ break;
+ }
+
+ return insn - insn_buf;
+}
+
+const struct bpf_verifier_ops cg_sysctl_verifier_ops = {
+ .get_func_proto = sysctl_func_proto,
+ .is_valid_access = sysctl_is_valid_access,
+ .convert_ctx_access = sysctl_convert_ctx_access,
+};
+
+const struct bpf_prog_ops cg_sysctl_prog_ops = {
+};
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index d995eedfdd16..92c9b8a32b50 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1888,6 +1888,9 @@ static int bpf_prog_attach(const union bpf_attr *attr)
case BPF_FLOW_DISSECTOR:
ptype = BPF_PROG_TYPE_FLOW_DISSECTOR;
break;
+ case BPF_CGROUP_SYSCTL:
+ ptype = BPF_PROG_TYPE_CGROUP_SYSCTL;
+ break;
default:
return -EINVAL;
}
@@ -1966,6 +1969,9 @@ static int bpf_prog_detach(const union bpf_attr *attr)
return lirc_prog_detach(attr);
case BPF_FLOW_DISSECTOR:
return skb_flow_dissector_bpf_prog_detach(attr);
+ case BPF_CGROUP_SYSCTL:
+ ptype = BPF_PROG_TYPE_CGROUP_SYSCTL;
+ break;
default:
return -EINVAL;
}
@@ -1999,6 +2005,7 @@ static int bpf_prog_query(const union bpf_attr *attr,
case BPF_CGROUP_UDP6_SENDMSG:
case BPF_CGROUP_SOCK_OPS:
case BPF_CGROUP_DEVICE:
+ case BPF_CGROUP_SYSCTL:
break;
case BPF_LIRC_MODE2:
return lirc_prog_query(attr, uattr);
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index f25b7c9c20ba..20808e3c95a8 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5267,6 +5267,7 @@ static int check_return_code(struct bpf_verifier_env *env)
case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
case BPF_PROG_TYPE_SOCK_OPS:
case BPF_PROG_TYPE_CGROUP_DEVICE:
+ case BPF_PROG_TYPE_CGROUP_SYSCTL:
break;
default:
return 0;
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.