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bpf: Make BPF_PROG_RUN_ARRAY return -err instead of allow boolean
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Right now BPF_PROG_RUN_ARRAY and related macros return 1 or 0
for whether the prog array allows or rejects whatever is being
hooked. The caller of these macros then return -EPERM or continue
processing based on thw macro's return value. Unforunately this is
inflexible, since -EPERM is the only err that can be returned.

This patch should be a no-op; it prepares for the next patch. The
returning of the -EPERM is moved to inside the macros, so the outer
functions are directly returning what the macros returned if they
are non-zero.

Signed-off-by: YiFei Zhu <zhuyifei@google.com>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/788abcdca55886d1f43274c918eaa9f792a9f33b.1639619851.git.zhuyifei@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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@zhuyifei1999
zhuyifei1999 authored and Alexei Starovoitov committed Jan 19, 2022
1 parent d81283d commit f10d059
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Showing 3 changed files with 25 additions and 34 deletions.
16 changes: 9 additions & 7 deletions include/linux/bpf.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1277,7 +1277,7 @@ static inline void bpf_reset_run_ctx(struct bpf_run_ctx *old_ctx)

typedef u32 (*bpf_prog_run_fn)(const struct bpf_prog *prog, const void *ctx);

static __always_inline u32
static __always_inline int
BPF_PROG_RUN_ARRAY_CG_FLAGS(const struct bpf_prog_array __rcu *array_rcu,
const void *ctx, bpf_prog_run_fn run_prog,
u32 *ret_flags)
Expand All @@ -1287,7 +1287,7 @@ BPF_PROG_RUN_ARRAY_CG_FLAGS(const struct bpf_prog_array __rcu *array_rcu,
const struct bpf_prog_array *array;
struct bpf_run_ctx *old_run_ctx;
struct bpf_cg_run_ctx run_ctx;
u32 ret = 1;
int ret = 0;
u32 func_ret;

migrate_disable();
Expand All @@ -1298,7 +1298,8 @@ BPF_PROG_RUN_ARRAY_CG_FLAGS(const struct bpf_prog_array __rcu *array_rcu,
while ((prog = READ_ONCE(item->prog))) {
run_ctx.prog_item = item;
func_ret = run_prog(prog, ctx);
ret &= (func_ret & 1);
if (!(func_ret & 1))
ret = -EPERM;
*(ret_flags) |= (func_ret >> 1);
item++;
}
Expand All @@ -1308,7 +1309,7 @@ BPF_PROG_RUN_ARRAY_CG_FLAGS(const struct bpf_prog_array __rcu *array_rcu,
return ret;
}

static __always_inline u32
static __always_inline int
BPF_PROG_RUN_ARRAY_CG(const struct bpf_prog_array __rcu *array_rcu,
const void *ctx, bpf_prog_run_fn run_prog)
{
Expand All @@ -1317,7 +1318,7 @@ BPF_PROG_RUN_ARRAY_CG(const struct bpf_prog_array __rcu *array_rcu,
const struct bpf_prog_array *array;
struct bpf_run_ctx *old_run_ctx;
struct bpf_cg_run_ctx run_ctx;
u32 ret = 1;
int ret = 0;

migrate_disable();
rcu_read_lock();
Expand All @@ -1326,7 +1327,8 @@ BPF_PROG_RUN_ARRAY_CG(const struct bpf_prog_array __rcu *array_rcu,
old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx);
while ((prog = READ_ONCE(item->prog))) {
run_ctx.prog_item = item;
ret &= run_prog(prog, ctx);
if (!run_prog(prog, ctx))
ret = -EPERM;
item++;
}
bpf_reset_run_ctx(old_run_ctx);
Expand Down Expand Up @@ -1394,7 +1396,7 @@ BPF_PROG_RUN_ARRAY(const struct bpf_prog_array __rcu *array_rcu,
u32 _ret; \
_ret = BPF_PROG_RUN_ARRAY_CG_FLAGS(array, ctx, func, &_flags); \
_cn = _flags & BPF_RET_SET_CN; \
if (_ret) \
if (!_ret) \
_ret = (_cn ? NET_XMIT_CN : NET_XMIT_SUCCESS); \
else \
_ret = (_cn ? NET_XMIT_DROP : -EPERM); \
Expand Down
41 changes: 15 additions & 26 deletions kernel/bpf/cgroup.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1080,7 +1080,6 @@ int __cgroup_bpf_run_filter_skb(struct sock *sk,
} else {
ret = BPF_PROG_RUN_ARRAY_CG(cgrp->bpf.effective[atype], skb,
__bpf_prog_run_save_cb);
ret = (ret == 1 ? 0 : -EPERM);
}
bpf_restore_data_end(skb, saved_data_end);
__skb_pull(skb, offset);
Expand All @@ -1107,10 +1106,9 @@ int __cgroup_bpf_run_filter_sk(struct sock *sk,
enum cgroup_bpf_attach_type atype)
{
struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
int ret;

ret = BPF_PROG_RUN_ARRAY_CG(cgrp->bpf.effective[atype], sk, bpf_prog_run);
return ret == 1 ? 0 : -EPERM;
return BPF_PROG_RUN_ARRAY_CG(cgrp->bpf.effective[atype], sk,
bpf_prog_run);
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sk);

Expand Down Expand Up @@ -1142,7 +1140,6 @@ int __cgroup_bpf_run_filter_sock_addr(struct sock *sk,
};
struct sockaddr_storage unspec;
struct cgroup *cgrp;
int ret;

/* Check socket family since not all sockets represent network
* endpoint (e.g. AF_UNIX).
Expand All @@ -1156,10 +1153,8 @@ int __cgroup_bpf_run_filter_sock_addr(struct sock *sk,
}

cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
ret = BPF_PROG_RUN_ARRAY_CG_FLAGS(cgrp->bpf.effective[atype], &ctx,
bpf_prog_run, flags);

return ret == 1 ? 0 : -EPERM;
return BPF_PROG_RUN_ARRAY_CG_FLAGS(cgrp->bpf.effective[atype], &ctx,
bpf_prog_run, flags);
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sock_addr);

Expand All @@ -1184,11 +1179,9 @@ int __cgroup_bpf_run_filter_sock_ops(struct sock *sk,
enum cgroup_bpf_attach_type atype)
{
struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
int ret;

ret = BPF_PROG_RUN_ARRAY_CG(cgrp->bpf.effective[atype], sock_ops,
bpf_prog_run);
return ret == 1 ? 0 : -EPERM;
return BPF_PROG_RUN_ARRAY_CG(cgrp->bpf.effective[atype], sock_ops,
bpf_prog_run);
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sock_ops);

Expand All @@ -1201,15 +1194,15 @@ int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
.major = major,
.minor = minor,
};
int allow;
int ret;

rcu_read_lock();
cgrp = task_dfl_cgroup(current);
allow = BPF_PROG_RUN_ARRAY_CG(cgrp->bpf.effective[atype], &ctx,
bpf_prog_run);
ret = BPF_PROG_RUN_ARRAY_CG(cgrp->bpf.effective[atype], &ctx,
bpf_prog_run);
rcu_read_unlock();

return !allow;
return ret;
}

static const struct bpf_func_proto *
Expand Down Expand Up @@ -1350,7 +1343,7 @@ int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
kfree(ctx.new_val);
}

return ret == 1 ? 0 : -EPERM;
return ret;
}

#ifdef CONFIG_NET
Expand Down Expand Up @@ -1455,10 +1448,8 @@ int __cgroup_bpf_run_filter_setsockopt(struct sock *sk, int *level,
&ctx, bpf_prog_run);
release_sock(sk);

if (!ret) {
ret = -EPERM;
if (ret)
goto out;
}

if (ctx.optlen == -1) {
/* optlen set to -1, bypass kernel */
Expand Down Expand Up @@ -1565,10 +1556,8 @@ int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
&ctx, bpf_prog_run);
release_sock(sk);

if (!ret) {
ret = -EPERM;
if (ret)
goto out;
}

if (ctx.optlen > max_optlen || ctx.optlen < 0) {
ret = -EFAULT;
Expand Down Expand Up @@ -1624,8 +1613,8 @@ int __cgroup_bpf_run_filter_getsockopt_kern(struct sock *sk, int level,

ret = BPF_PROG_RUN_ARRAY_CG(cgrp->bpf.effective[CGROUP_GETSOCKOPT],
&ctx, bpf_prog_run);
if (!ret)
return -EPERM;
if (ret)
return ret;

if (ctx.optlen > *optlen)
return -EFAULT;
Expand Down
2 changes: 1 addition & 1 deletion security/device_cgroup.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -838,7 +838,7 @@ int devcgroup_check_permission(short type, u32 major, u32 minor, short access)
int rc = BPF_CGROUP_RUN_PROG_DEVICE_CGROUP(type, major, minor, access);

if (rc)
return -EPERM;
return rc;

#ifdef CONFIG_CGROUP_DEVICE
return devcgroup_legacy_check_permission(type, major, minor, access);
Expand Down

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