With the new SECCOMP_FILTER_FLAG_LOG, we need to be able to extract these flags for checkpoint restore, since they describe the state of a filter.
So, let's add PTRACE_SECCOMP_GET_METADATA, similar to ..._GET_FILTER, which returns the metadata of the nth filter (right now, just the flags). Hopefully this will be future proof, and new per-filter metadata can be added to this struct. v3: * use GET_METADATA instead of GET_FLAGS v4: * resend Signed-off-by: Tycho Andersen <[email protected]> CC: Kees Cook <[email protected]> CC: Andy Lutomirski <[email protected]> CC: Oleg Nesterov <[email protected]> --- include/linux/seccomp.h | 8 ++++++++ include/uapi/linux/ptrace.h | 6 ++++++ kernel/ptrace.c | 4 ++++ kernel/seccomp.c | 34 ++++++++++++++++++++++++++++++++++ 4 files changed, 52 insertions(+) diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h index 10f25f7e4304..c723a5c4e3ff 100644 --- a/include/linux/seccomp.h +++ b/include/linux/seccomp.h @@ -95,11 +95,19 @@ static inline void get_seccomp_filter(struct task_struct *tsk) #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE) extern long seccomp_get_filter(struct task_struct *task, unsigned long filter_off, void __user *data); +extern long seccomp_get_metadata(struct task_struct *task, + unsigned long filter_off, void __user *data); #else static inline long seccomp_get_filter(struct task_struct *task, unsigned long n, void __user *data) { return -EINVAL; } +static inline long seccomp_get_metadata(struct task_struct *task, + unsigned long filter_off, + void __user *data) +{ + return -EINVAL; +} #endif /* CONFIG_SECCOMP_FILTER && CONFIG_CHECKPOINT_RESTORE */ #endif /* _LINUX_SECCOMP_H */ diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h index e3939e00980b..e46d82b91166 100644 --- a/include/uapi/linux/ptrace.h +++ b/include/uapi/linux/ptrace.h @@ -66,6 +66,12 @@ struct ptrace_peeksiginfo_args { #define PTRACE_SETSIGMASK 0x420b #define PTRACE_SECCOMP_GET_FILTER 0x420c +#define PTRACE_SECCOMP_GET_METADATA 0x420d + +struct seccomp_metadata { + unsigned long filter_off; /* Input: which filter */ + unsigned int flags; /* Output: filter's flags */ +}; /* Read signals from a shared (process wide) queue */ #define PTRACE_PEEKSIGINFO_SHARED (1 << 0) diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 84b1367935e4..58291e9f3276 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -1092,6 +1092,10 @@ int ptrace_request(struct task_struct *child, long request, ret = seccomp_get_filter(child, addr, datavp); break; + case PTRACE_SECCOMP_GET_METADATA: + ret = seccomp_get_metadata(child, addr, datavp); + break; + default: break; } diff --git a/kernel/seccomp.c b/kernel/seccomp.c index bad457862ee0..7f1f2f3ea549 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -1061,6 +1061,40 @@ long seccomp_get_filter(struct task_struct *task, unsigned long filter_off, __put_seccomp_filter(filter); return ret; } + +long seccomp_get_metadata(struct task_struct *task, + unsigned long size, void __user *data) +{ + long ret; + struct seccomp_filter *filter; + struct seccomp_metadata kmd = {}; + + if (!capable(CAP_SYS_ADMIN) || + current->seccomp.mode != SECCOMP_MODE_DISABLED) { + return -EACCES; + } + + size = min_t(unsigned long, size, sizeof(kmd)); + + if (copy_from_user(&kmd, data, size)) + return -EFAULT; + + filter = get_nth_filter(task, kmd.filter_off); + if (IS_ERR(filter)) + return PTR_ERR(filter); + + memset(&kmd, 0, sizeof(kmd)); + if (filter->log) + kmd.flags |= SECCOMP_FILTER_FLAG_LOG; + + ret = size; + if (copy_to_user(data, &kmd, size)) + ret = -EFAULT; + + __put_seccomp_filter(filter); + return ret; + +} #endif #ifdef CONFIG_SYSCTL -- 2.14.1
