* [PATCH bpf-next 0/3] Modify some code in sysctl_net_core.c
@ 2022-05-09 6:57 Tiezhu Yang
2022-05-09 6:57 ` [PATCH bpf-next 1/3] net: sysctl: Use SYSCTL_TWO instead of &two Tiezhu Yang
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Tiezhu Yang @ 2022-05-09 6:57 UTC (permalink / raw)
To: davem, Jakub Kicinski, Paolo Abeni, Alexei Starovoitov,
Daniel Borkmann, Andrii Nakryiko
Cc: netdev, bpf, linux-kernel
Tiezhu Yang (3):
net: sysctl: Use SYSCTL_TWO instead of &two
net: sysctl: No need to check CAP_SYS_ADMIN for bpf_jit_*
bpf: Print some info if disable bpf_jit_enable failed
net/core/sysctl_net_core.c | 22 +++++++++-------------
1 file changed, 9 insertions(+), 13 deletions(-)
--
2.1.0
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH bpf-next 1/3] net: sysctl: Use SYSCTL_TWO instead of &two
2022-05-09 6:57 [PATCH bpf-next 0/3] Modify some code in sysctl_net_core.c Tiezhu Yang
@ 2022-05-09 6:57 ` Tiezhu Yang
2022-05-09 6:57 ` [PATCH bpf-next 2/3] net: sysctl: No need to check CAP_SYS_ADMIN for bpf_jit_* Tiezhu Yang
2022-05-09 6:57 ` [PATCH bpf-next 3/3] bpf: Print some info if disable bpf_jit_enable failed Tiezhu Yang
2 siblings, 0 replies; 6+ messages in thread
From: Tiezhu Yang @ 2022-05-09 6:57 UTC (permalink / raw)
To: davem, Jakub Kicinski, Paolo Abeni, Alexei Starovoitov,
Daniel Borkmann, Andrii Nakryiko
Cc: netdev, bpf, linux-kernel
It is better to use SYSCTL_TWO instead of &two, and then we can
remove the variable "two" in net/core/sysctl_net_core.c.
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
net/core/sysctl_net_core.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 8295e58..cf00dd7 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -25,7 +25,6 @@
#include "dev.h"
-static int two = 2;
static int three = 3;
static int int_3600 = 3600;
static int min_sndbuf = SOCK_MIN_SNDBUF;
@@ -390,7 +389,7 @@ static struct ctl_table net_core_table[] = {
.extra2 = SYSCTL_ONE,
# else
.extra1 = SYSCTL_ZERO,
- .extra2 = &two,
+ .extra2 = SYSCTL_TWO,
# endif
},
# ifdef CONFIG_HAVE_EBPF_JIT
@@ -401,7 +400,7 @@ static struct ctl_table net_core_table[] = {
.mode = 0600,
.proc_handler = proc_dointvec_minmax_bpf_restricted,
.extra1 = SYSCTL_ZERO,
- .extra2 = &two,
+ .extra2 = SYSCTL_TWO,
},
{
.procname = "bpf_jit_kallsyms",
@@ -546,7 +545,7 @@ static struct ctl_table net_core_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
- .extra2 = &two,
+ .extra2 = SYSCTL_TWO,
},
{
.procname = "devconf_inherit_init_net",
--
2.1.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH bpf-next 2/3] net: sysctl: No need to check CAP_SYS_ADMIN for bpf_jit_*
2022-05-09 6:57 [PATCH bpf-next 0/3] Modify some code in sysctl_net_core.c Tiezhu Yang
2022-05-09 6:57 ` [PATCH bpf-next 1/3] net: sysctl: Use SYSCTL_TWO instead of &two Tiezhu Yang
@ 2022-05-09 6:57 ` Tiezhu Yang
2022-05-09 15:02 ` Daniel Borkmann
2022-05-09 6:57 ` [PATCH bpf-next 3/3] bpf: Print some info if disable bpf_jit_enable failed Tiezhu Yang
2 siblings, 1 reply; 6+ messages in thread
From: Tiezhu Yang @ 2022-05-09 6:57 UTC (permalink / raw)
To: davem, Jakub Kicinski, Paolo Abeni, Alexei Starovoitov,
Daniel Borkmann, Andrii Nakryiko
Cc: netdev, bpf, linux-kernel
The mode of the following procnames are defined as 0644, 0600, 0600
and 0600 respectively in net_core_table[], normal user can not write
them, so no need to check CAP_SYS_ADMIN in the related proc_handler
function, just remove the checks.
/proc/sys/net/core/bpf_jit_enable
/proc/sys/net/core/bpf_jit_harden
/proc/sys/net/core/bpf_jit_kallsyms
/proc/sys/net/core/bpf_jit_limit
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
net/core/sysctl_net_core.c | 9 ---------
1 file changed, 9 deletions(-)
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index cf00dd7..059352b 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -268,9 +268,6 @@ static int proc_dointvec_minmax_bpf_enable(struct ctl_table *table, int write,
int ret, jit_enable = *(int *)table->data;
struct ctl_table tmp = *table;
- if (write && !capable(CAP_SYS_ADMIN))
- return -EPERM;
-
tmp.data = &jit_enable;
ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
if (write && !ret) {
@@ -291,9 +288,6 @@ static int
proc_dointvec_minmax_bpf_restricted(struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
-
return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
}
# endif /* CONFIG_HAVE_EBPF_JIT */
@@ -302,9 +296,6 @@ static int
proc_dolongvec_minmax_bpf_restricted(struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
-
return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
}
#endif
--
2.1.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH bpf-next 3/3] bpf: Print some info if disable bpf_jit_enable failed
2022-05-09 6:57 [PATCH bpf-next 0/3] Modify some code in sysctl_net_core.c Tiezhu Yang
2022-05-09 6:57 ` [PATCH bpf-next 1/3] net: sysctl: Use SYSCTL_TWO instead of &two Tiezhu Yang
2022-05-09 6:57 ` [PATCH bpf-next 2/3] net: sysctl: No need to check CAP_SYS_ADMIN for bpf_jit_* Tiezhu Yang
@ 2022-05-09 6:57 ` Tiezhu Yang
2 siblings, 0 replies; 6+ messages in thread
From: Tiezhu Yang @ 2022-05-09 6:57 UTC (permalink / raw)
To: davem, Jakub Kicinski, Paolo Abeni, Alexei Starovoitov,
Daniel Borkmann, Andrii Nakryiko
Cc: netdev, bpf, linux-kernel
A user told me that bpf_jit_enable can be disabled on one system, but he
failed to disable bpf_jit_enable on the other system:
# echo 0 > /proc/sys/net/core/bpf_jit_enable
bash: echo: write error: Invalid argument
No useful info is available through the dmesg log, a quick analysis shows
that the issue is related with CONFIG_BPF_JIT_ALWAYS_ON.
When CONFIG_BPF_JIT_ALWAYS_ON is enabled, bpf_jit_enable is permanently set
to 1 and setting any other value than that will return failure.
It is better to print some info to tell the user if disable bpf_jit_enable
failed.
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
net/core/sysctl_net_core.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 059352b..f8a1d450 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -266,6 +266,8 @@ static int proc_dointvec_minmax_bpf_enable(struct ctl_table *table, int write,
loff_t *ppos)
{
int ret, jit_enable = *(int *)table->data;
+ int min = *(int *)table->extra1;
+ int max = *(int *)table->extra2;
struct ctl_table tmp = *table;
tmp.data = &jit_enable;
@@ -280,6 +282,10 @@ static int proc_dointvec_minmax_bpf_enable(struct ctl_table *table, int write,
ret = -EPERM;
}
}
+
+ if (write && ret && min == max)
+ pr_info("CONFIG_BPF_JIT_ALWAYS_ON is enabled, bpf_jit_enable is permanently set to 1.\n");
+
return ret;
}
--
2.1.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next 2/3] net: sysctl: No need to check CAP_SYS_ADMIN for bpf_jit_*
2022-05-09 6:57 ` [PATCH bpf-next 2/3] net: sysctl: No need to check CAP_SYS_ADMIN for bpf_jit_* Tiezhu Yang
@ 2022-05-09 15:02 ` Daniel Borkmann
2022-05-10 2:42 ` Tiezhu Yang
0 siblings, 1 reply; 6+ messages in thread
From: Daniel Borkmann @ 2022-05-09 15:02 UTC (permalink / raw)
To: Tiezhu Yang, davem, Jakub Kicinski, Paolo Abeni,
Alexei Starovoitov, Andrii Nakryiko
Cc: netdev, bpf, linux-kernel
On 5/9/22 8:57 AM, Tiezhu Yang wrote:
> The mode of the following procnames are defined as 0644, 0600, 0600
> and 0600 respectively in net_core_table[], normal user can not write
> them, so no need to check CAP_SYS_ADMIN in the related proc_handler
> function, just remove the checks.
>
> /proc/sys/net/core/bpf_jit_enable
> /proc/sys/net/core/bpf_jit_harden
> /proc/sys/net/core/bpf_jit_kallsyms
> /proc/sys/net/core/bpf_jit_limit
>
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
I don't think we can make this assumption - there are various other (non-BPF)
sysctl handlers in the tree doing similar check to prevent from userns' based
CAP_SYS_ADMIN.
> ---
> net/core/sysctl_net_core.c | 9 ---------
> 1 file changed, 9 deletions(-)
>
> diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
> index cf00dd7..059352b 100644
> --- a/net/core/sysctl_net_core.c
> +++ b/net/core/sysctl_net_core.c
> @@ -268,9 +268,6 @@ static int proc_dointvec_minmax_bpf_enable(struct ctl_table *table, int write,
> int ret, jit_enable = *(int *)table->data;
> struct ctl_table tmp = *table;
>
> - if (write && !capable(CAP_SYS_ADMIN))
> - return -EPERM;
> -
> tmp.data = &jit_enable;
> ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
> if (write && !ret) {
> @@ -291,9 +288,6 @@ static int
> proc_dointvec_minmax_bpf_restricted(struct ctl_table *table, int write,
> void *buffer, size_t *lenp, loff_t *ppos)
> {
> - if (!capable(CAP_SYS_ADMIN))
> - return -EPERM;
> -
> return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
> }
> # endif /* CONFIG_HAVE_EBPF_JIT */
> @@ -302,9 +296,6 @@ static int
> proc_dolongvec_minmax_bpf_restricted(struct ctl_table *table, int write,
> void *buffer, size_t *lenp, loff_t *ppos)
> {
> - if (!capable(CAP_SYS_ADMIN))
> - return -EPERM;
> -
> return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
> }
> #endif
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next 2/3] net: sysctl: No need to check CAP_SYS_ADMIN for bpf_jit_*
2022-05-09 15:02 ` Daniel Borkmann
@ 2022-05-10 2:42 ` Tiezhu Yang
0 siblings, 0 replies; 6+ messages in thread
From: Tiezhu Yang @ 2022-05-10 2:42 UTC (permalink / raw)
To: Daniel Borkmann, davem, Jakub Kicinski, Paolo Abeni,
Alexei Starovoitov, Andrii Nakryiko
Cc: netdev, bpf, linux-kernel
On 05/09/2022 11:02 PM, Daniel Borkmann wrote:
> On 5/9/22 8:57 AM, Tiezhu Yang wrote:
>> The mode of the following procnames are defined as 0644, 0600, 0600
>> and 0600 respectively in net_core_table[], normal user can not write
>> them, so no need to check CAP_SYS_ADMIN in the related proc_handler
>> function, just remove the checks.
>>
>> /proc/sys/net/core/bpf_jit_enable
>> /proc/sys/net/core/bpf_jit_harden
>> /proc/sys/net/core/bpf_jit_kallsyms
>> /proc/sys/net/core/bpf_jit_limit
>>
>> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
>
> I don't think we can make this assumption - there are various other
> (non-BPF)
> sysctl handlers in the tree doing similar check to prevent from userns'
> based
> CAP_SYS_ADMIN.
>
OK, thank you for your reply, let me drop this patch now,
I will send v2 (patch #1 and #3) later.
Thanks,
Tiezhu
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-05-10 2:42 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-05-09 6:57 [PATCH bpf-next 0/3] Modify some code in sysctl_net_core.c Tiezhu Yang
2022-05-09 6:57 ` [PATCH bpf-next 1/3] net: sysctl: Use SYSCTL_TWO instead of &two Tiezhu Yang
2022-05-09 6:57 ` [PATCH bpf-next 2/3] net: sysctl: No need to check CAP_SYS_ADMIN for bpf_jit_* Tiezhu Yang
2022-05-09 15:02 ` Daniel Borkmann
2022-05-10 2:42 ` Tiezhu Yang
2022-05-09 6:57 ` [PATCH bpf-next 3/3] bpf: Print some info if disable bpf_jit_enable failed Tiezhu Yang
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).