2022-04-04 21:41:39

by CGEL

Subject: [PATCH v2] audit: do a quick exit when syscall number is less than 0

From: Yang Yang <[email protected]>

Userspace may use syscall with syscall number less than 0 by calling
syscall(syscall_num,..). This kind of syscall could never be audited,
because auditctl requires rule with syscall number >=0. Therefore we
better do a quick handle no need to gohead with this situation.

Note that auditctl may set rules auditing invalid syscall with syscall
number bigger than NR_syscalls, to keep this mechanism working, we do
no more check(context->major bigger than NR_syscalls or not).

Signed-off-by: Yang Yang <[email protected]>
Reported-by: Zeal Robot <[email protected]>
---
v2:
- cancel checking against NR_syscalls
---
kernel/auditsc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index ea2ee1181921..79118c811853 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -2077,7 +2077,8 @@ void __audit_syscall_exit(int success, long return_code)
struct audit_context *context = audit_context();

if (!context || context->dummy ||
- context->context != AUDIT_CTX_SYSCALL)
+ context->context != AUDIT_CTX_SYSCALL ||
+ unlikely(context->major < 0))
goto out;

/* this may generate CONFIG_CHANGE records */
--
2.25.1

2022-04-05 01:12:12

by Paul Moore

Subject: Re: [PATCH v2] audit: do a quick exit when syscall number is less than 0

On Sun, Apr 3, 2022 at 10:23 PM <[email protected]> wrote:
>
> From: Yang Yang <[email protected]>
>
> Userspace may use syscall with syscall number less than 0 by calling
> syscall(syscall_num,..). This kind of syscall could never be audited,
> because auditctl requires rule with syscall number >=0. Therefore we
> better do a quick handle no need to gohead with this situation.
>
> Note that auditctl may set rules auditing invalid syscall with syscall
> number bigger than NR_syscalls, to keep this mechanism working, we do
> no more check(context->major bigger than NR_syscalls or not).
>
> Signed-off-by: Yang Yang <[email protected]>
> Reported-by: Zeal Robot <[email protected]>
> ---
> v2:
> - cancel checking against NR_syscalls
> ---
> kernel/auditsc.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)

As discussed previously, this is not something I want to merge
upstream at this time.

--
paul-moore.com