diff options
author | Kees Cook <keescook@chromium.org> | 2014-06-25 16:08:24 -0700 |
---|---|---|
committer | JP Abgrall <jpa@google.com> | 2014-08-28 01:51:54 +0000 |
commit | a75a29b16e1f3eb2afcb9b2567edfc4cd8899635 (patch) | |
tree | 6ff23d6e6711cba6c7e64f2d786a992fbf50f98b /kernel | |
parent | 1a63bcec4fb055acbed31a5cf1cc40e968cf0664 (diff) |
seccomp: add "seccomp" syscall
This adds the new "seccomp" syscall with both an "operation" and "flags"
parameter for future expansion. The third argument is a pointer value,
used with the SECCOMP_SET_MODE_FILTER operation. Currently, flags must
be 0. This is functionally equivalent to prctl(PR_SET_SECCOMP, ...).
In addition to the TSYNC flag later in this patch series, there is a
non-zero chance that this syscall could be used for configuring a fixed
argument area for seccomp-tracer-aware processes to pass syscall arguments
in the future. Hence, the use of "seccomp" not simply "seccomp_add_filter"
for this syscall. Additionally, this syscall uses operation, flags,
and user pointer for arguments because strictly passing arguments via
a user pointer would mean seccomp itself would be unable to trivially
filter the seccomp syscall itself.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Conflicts:
arch/x86/syscalls/syscall_32.tbl
arch/x86/syscalls/syscall_64.tbl
include/uapi/asm-generic/unistd.h
kernel/seccomp.c
Change-Id: Id7a365079829fd9164315dec75d6ee415c29b176
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/seccomp.c | 55 | ||||
-rw-r--r-- | kernel/sys_ni.c | 3 |
2 files changed, 53 insertions, 5 deletions
diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 793bec19b6c7..47dc5c59621e 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -18,6 +18,7 @@ #include <linux/compat.h> #include <linux/sched.h> #include <linux/seccomp.h> +#include <linux/syscalls.h> /* #define SECCOMP_DEBUG 1 */ @@ -325,7 +326,7 @@ fail: * * Returns 0 on success and non-zero otherwise. */ -long seccomp_attach_user_filter(char __user *user_filter) +static long seccomp_attach_user_filter(const char __user *user_filter) { struct sock_fprog fprog; long ret = -EFAULT; @@ -527,6 +528,7 @@ out: #ifdef CONFIG_SECCOMP_FILTER /** * seccomp_set_mode_filter: internal function for setting seccomp filter + * @flags: flags to change filter behavior * @filter: struct sock_fprog containing filter * * This function may be called repeatedly to install additional filters. @@ -537,11 +539,16 @@ out: * * Returns 0 on success or -EINVAL on failure. */ -static long seccomp_set_mode_filter(char __user *filter) +static long seccomp_set_mode_filter(unsigned int flags, + const char __user *filter) { const unsigned long seccomp_mode = SECCOMP_MODE_FILTER; long ret = -EINVAL; + /* Validate flags. */ + if (flags != 0) + goto out; + if (!seccomp_may_assign_mode(seccomp_mode)) goto out; @@ -554,12 +561,35 @@ out: return ret; } #else -static inline long seccomp_set_mode_filter(char __user *filter) +static inline long seccomp_set_mode_filter(unsigned int flags, + const char __user *filter) { return -EINVAL; } #endif +/* Common entry point for both prctl and syscall. */ +static long do_seccomp(unsigned int op, unsigned int flags, + const char __user *uargs) +{ + switch (op) { + case SECCOMP_SET_MODE_STRICT: + if (flags != 0 || uargs != NULL) + return -EINVAL; + return seccomp_set_mode_strict(); + case SECCOMP_SET_MODE_FILTER: + return seccomp_set_mode_filter(flags, uargs); + default: + return -EINVAL; + } +} + +SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags, + const char __user *, uargs) +{ + return do_seccomp(op, flags, uargs); +} + /** * prctl_set_seccomp: configures current->seccomp.mode * @seccomp_mode: requested mode to use @@ -569,12 +599,27 @@ static inline long seccomp_set_mode_filter(char __user *filter) */ long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter) { + unsigned int op; + char __user *uargs; + switch (seccomp_mode) { case SECCOMP_MODE_STRICT: - return seccomp_set_mode_strict(); + op = SECCOMP_SET_MODE_STRICT; + /* + * Setting strict mode through prctl always ignored filter, + * so make sure it is always NULL here to pass the internal + * check in do_seccomp(). + */ + uargs = NULL; + break; case SECCOMP_MODE_FILTER: - return seccomp_set_mode_filter(filter); + op = SECCOMP_SET_MODE_FILTER; + uargs = filter; + break; default: return -EINVAL; } + + /* prctl interface doesn't have flags, so they are always zero. */ + return do_seccomp(op, 0, uargs); } diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c index 7078052284fd..7e7fc0a082c4 100644 --- a/kernel/sys_ni.c +++ b/kernel/sys_ni.c @@ -209,3 +209,6 @@ cond_syscall(compat_sys_open_by_handle_at); /* compare kernel pointers */ cond_syscall(sys_kcmp); + +/* operate on Secure Computing state */ +cond_syscall(sys_seccomp); |