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f8e529ed94
This patch adds support for dumping a process' (classic BPF) seccomp
filters via ptrace.
PTRACE_SECCOMP_GET_FILTER allows the tracer to dump the user's classic BPF
seccomp filters. addr should be an integer which represents the ith seccomp
filter (0 is the most recently installed filter). data should be a struct
sock_filter * with enough room for the ith filter, or NULL, in which case
the filter is not saved. The return value for this command is the number of
BPF instructions the program represents, or negative in the case of errors.
Command specific errors are ENOENT: which indicates that there is no ith
filter in this seccomp tree, and EMEDIUMTYPE, which indicates that the ith
filter was not installed as a classic BPF filter.
A caveat with this approach is that there is no way to get explicitly at
the heirarchy of seccomp filters, and users need to memcmp() filters to
decide which are inherited. This means that a task which installs two of
the same filter can potentially confuse users of this interface.
v2: * make save_orig const
* check that the orig_prog exists (not necessary right now, but when
grows eBPF support it will be)
* s/n/filter_off and make it an unsigned long to match ptrace
* count "down" the tree instead of "up" when passing a filter offset
v3: * don't take the current task's lock for inspecting its seccomp mode
* use a 0x42** constant for the ptrace command value
v4: * don't copy to userspace while holding spinlocks
v5: * add another condition to WARN_ON
v6: * rebase on net-next
Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
Acked-by: Kees Cook <keescook@chromium.org>
CC: Will Drewry <wad@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
CC: Andy Lutomirski <luto@amacapital.net>
CC: Pavel Emelyanov <xemul@parallels.com>
CC: Serge E. Hallyn <serge.hallyn@ubuntu.com>
CC: Alexei Starovoitov <ast@kernel.org>
CC: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
109 lines
2.6 KiB
C
109 lines
2.6 KiB
C
#ifndef _LINUX_SECCOMP_H
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#define _LINUX_SECCOMP_H
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#include <uapi/linux/seccomp.h>
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#define SECCOMP_FILTER_FLAG_MASK (SECCOMP_FILTER_FLAG_TSYNC)
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#ifdef CONFIG_SECCOMP
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#include <linux/thread_info.h>
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#include <asm/seccomp.h>
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struct seccomp_filter;
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/**
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* struct seccomp - the state of a seccomp'ed process
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*
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* @mode: indicates one of the valid values above for controlled
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* system calls available to a process.
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* @filter: must always point to a valid seccomp-filter or NULL as it is
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* accessed without locking during system call entry.
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*
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* @filter must only be accessed from the context of current as there
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* is no read locking.
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*/
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struct seccomp {
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int mode;
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struct seccomp_filter *filter;
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};
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#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
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extern int __secure_computing(void);
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static inline int secure_computing(void)
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{
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if (unlikely(test_thread_flag(TIF_SECCOMP)))
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return __secure_computing();
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return 0;
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}
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#define SECCOMP_PHASE1_OK 0
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#define SECCOMP_PHASE1_SKIP 1
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extern u32 seccomp_phase1(struct seccomp_data *sd);
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int seccomp_phase2(u32 phase1_result);
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#else
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extern void secure_computing_strict(int this_syscall);
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#endif
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extern long prctl_get_seccomp(void);
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extern long prctl_set_seccomp(unsigned long, char __user *);
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static inline int seccomp_mode(struct seccomp *s)
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{
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return s->mode;
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}
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#else /* CONFIG_SECCOMP */
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#include <linux/errno.h>
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struct seccomp { };
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struct seccomp_filter { };
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#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
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static inline int secure_computing(void) { return 0; }
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#else
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static inline void secure_computing_strict(int this_syscall) { return; }
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#endif
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static inline long prctl_get_seccomp(void)
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{
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return -EINVAL;
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}
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static inline long prctl_set_seccomp(unsigned long arg2, char __user *arg3)
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{
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return -EINVAL;
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}
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static inline int seccomp_mode(struct seccomp *s)
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{
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return SECCOMP_MODE_DISABLED;
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}
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#endif /* CONFIG_SECCOMP */
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#ifdef CONFIG_SECCOMP_FILTER
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extern void put_seccomp_filter(struct task_struct *tsk);
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extern void get_seccomp_filter(struct task_struct *tsk);
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#else /* CONFIG_SECCOMP_FILTER */
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static inline void put_seccomp_filter(struct task_struct *tsk)
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{
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return;
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}
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static inline void get_seccomp_filter(struct task_struct *tsk)
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{
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return;
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}
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#endif /* CONFIG_SECCOMP_FILTER */
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#if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
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extern long seccomp_get_filter(struct task_struct *task,
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unsigned long filter_off, void __user *data);
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#else
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static inline long seccomp_get_filter(struct task_struct *task,
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unsigned long n, void __user *data)
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{
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return -EINVAL;
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}
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#endif /* CONFIG_SECCOMP_FILTER && CONFIG_CHECKPOINT_RESTORE */
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#endif /* _LINUX_SECCOMP_H */
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