diff options
author | Tyler Hicks <tyhicks@canonical.com> | 2017-08-11 04:33:53 +0000 |
---|---|---|
committer | Kees Cook <keescook@chromium.org> | 2017-08-14 13:46:44 -0700 |
commit | d612b1fd8010d0d67b5287fe146b8b55bcbb8655 (patch) | |
tree | cadcaeebf71ffa28aced54e9fc8b7c0ee42cc6d3 /kernel/seccomp.c | |
parent | 8e5f1ad116df6b0de65eac458d5e7c318d1c05af (diff) | |
download | op-kernel-dev-d612b1fd8010d0d67b5287fe146b8b55bcbb8655.zip op-kernel-dev-d612b1fd8010d0d67b5287fe146b8b55bcbb8655.tar.gz |
seccomp: Operation for checking if an action is available
Userspace code that needs to check if the kernel supports a given action
may not be able to use the /proc/sys/kernel/seccomp/actions_avail
sysctl. The process may be running in a sandbox and, therefore,
sufficient filesystem access may not be available. This patch adds an
operation to the seccomp(2) syscall that allows userspace code to ask
the kernel if a given action is available.
If the action is supported by the kernel, 0 is returned. If the action
is not supported by the kernel, -1 is returned with errno set to
-EOPNOTSUPP. If this check is attempted on a kernel that doesn't support
this new operation, -1 is returned with errno set to -EINVAL meaning
that userspace code will have the ability to differentiate between the
two error cases.
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Suggested-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'kernel/seccomp.c')
-rw-r--r-- | kernel/seccomp.c | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 5f19f41..7a6089f 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -808,6 +808,27 @@ static inline long seccomp_set_mode_filter(unsigned int flags, } #endif +static long seccomp_get_action_avail(const char __user *uaction) +{ + u32 action; + + if (copy_from_user(&action, uaction, sizeof(action))) + return -EFAULT; + + switch (action) { + case SECCOMP_RET_KILL: + case SECCOMP_RET_TRAP: + case SECCOMP_RET_ERRNO: + case SECCOMP_RET_TRACE: + case SECCOMP_RET_ALLOW: + break; + default: + return -EOPNOTSUPP; + } + + return 0; +} + /* Common entry point for both prctl and syscall. */ static long do_seccomp(unsigned int op, unsigned int flags, const char __user *uargs) @@ -819,6 +840,11 @@ static long do_seccomp(unsigned int op, unsigned int flags, return seccomp_set_mode_strict(); case SECCOMP_SET_MODE_FILTER: return seccomp_set_mode_filter(flags, uargs); + case SECCOMP_GET_ACTION_AVAIL: + if (flags != 0) + return -EINVAL; + + return seccomp_get_action_avail(uargs); default: return -EINVAL; } |