diff options
author | Will Drewry <wad@chromium.org> | 2012-04-12 16:48:01 -0500 |
---|---|---|
committer | James Morris <james.l.morris@oracle.com> | 2012-04-14 11:13:21 +1000 |
commit | bb6ea4301a1109afdacaee576fedbfcd7152fc86 (patch) | |
tree | 5412219057d8e0ec2a30d0a1ad4f6b7dd398c754 | |
parent | a0727e8ce513fe6890416da960181ceb10fbfae6 (diff) |
seccomp: Add SECCOMP_RET_TRAP
Adds a new return value to seccomp filters that triggers a SIGSYS to be
delivered with the new SYS_SECCOMP si_code.
This allows in-process system call emulation, including just specifying
an errno or cleanly dumping core, rather than just dying.
Suggested-by: Markus Gutschke <markus@chromium.org>
Suggested-by: Julien Tinnes <jln@chromium.org>
Signed-off-by: Will Drewry <wad@chromium.org>
Acked-by: Eric Paris <eparis@redhat.com>
v18: - acked-by, rebase
- don't mention secure_computing_int() anymore
v15: - use audit_seccomp/skip
- pad out error spacing; clean up switch (indan@nul.nu)
v14: - n/a
v13: - rebase on to 88ebdda6159ffc15699f204c33feb3e431bf9bdc
v12: - rebase on to linux-next
v11: - clarify the comment (indan@nul.nu)
- s/sigtrap/sigsys
v10: - use SIGSYS, syscall_get_arch, updates arch/Kconfig
note suggested-by (though original suggestion had other behaviors)
v9: - changes to SIGILL
v8: - clean up based on changes to dependent patches
v7: - introduction
Signed-off-by: James Morris <james.l.morris@oracle.com>
-rw-r--r-- | arch/Kconfig | 14 | ||||
-rw-r--r-- | include/asm-generic/siginfo.h | 2 | ||||
-rw-r--r-- | include/linux/seccomp.h | 1 | ||||
-rw-r--r-- | kernel/seccomp.c | 26 |
4 files changed, 37 insertions, 6 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index beaab68c13b..66aef13f603 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -219,11 +219,15 @@ config ARCH_WANT_OLD_COMPAT_IPC config HAVE_ARCH_SECCOMP_FILTER bool help - This symbol should be selected by an architecure if it provides - asm/syscall.h, specifically syscall_get_arguments(), - syscall_get_arch(), and syscall_set_return_value(). Additionally, - its system call entry path must respect a return value of -1 from - __secure_computing() and/or secure_computing(). + This symbol should be selected by an architecure if it provides: + asm/syscall.h: + - syscall_get_arch() + - syscall_get_arguments() + - syscall_rollback() + - syscall_set_return_value() + SIGSYS siginfo_t support must be implemented. + __secure_computing()/secure_computing()'s return value must be + checked, with -1 resulting in the syscall being skipped. config SECCOMP_FILTER def_bool y diff --git a/include/asm-generic/siginfo.h b/include/asm-generic/siginfo.h index 31306f55eb0..af5d0350f84 100644 --- a/include/asm-generic/siginfo.h +++ b/include/asm-generic/siginfo.h @@ -93,7 +93,7 @@ typedef struct siginfo { /* SIGSYS */ struct { - void __user *_call_addr; /* calling insn */ + void __user *_call_addr; /* calling user insn */ int _syscall; /* triggering system call number */ unsigned int _arch; /* AUDIT_ARCH_* of syscall */ } _sigsys; diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h index b4ce2c816e0..317ccb78cf4 100644 --- a/include/linux/seccomp.h +++ b/include/linux/seccomp.h @@ -19,6 +19,7 @@ * selects the least permissive choice. */ #define SECCOMP_RET_KILL 0x00000000U /* kill the task immediately */ +#define SECCOMP_RET_TRAP 0x00030000U /* disallow and force a SIGSYS */ #define SECCOMP_RET_ERRNO 0x00050000U /* returns an errno */ #define SECCOMP_RET_ALLOW 0x7fff0000U /* allow */ diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 5f78fb6d221..9c3830692a0 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -332,6 +332,26 @@ void put_seccomp_filter(struct task_struct *tsk) kfree(freeme); } } + +/** + * seccomp_send_sigsys - signals the task to allow in-process syscall emulation + * @syscall: syscall number to send to userland + * @reason: filter-supplied reason code to send to userland (via si_errno) + * + * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info. + */ +static void seccomp_send_sigsys(int syscall, int reason) +{ + struct siginfo info; + memset(&info, 0, sizeof(info)); + info.si_signo = SIGSYS; + info.si_code = SYS_SECCOMP; + info.si_call_addr = (void __user *)KSTK_EIP(current); + info.si_errno = reason; + info.si_arch = syscall_get_arch(current, task_pt_regs(current)); + info.si_syscall = syscall; + force_sig_info(SIGSYS, &info, current); +} #endif /* CONFIG_SECCOMP_FILTER */ /* @@ -382,6 +402,12 @@ int __secure_computing(int this_syscall) syscall_set_return_value(current, task_pt_regs(current), -data, 0); goto skip; + case SECCOMP_RET_TRAP: + /* Show the handler the original registers. */ + syscall_rollback(current, task_pt_regs(current)); + /* Let the filter pass back 16 bits of data. */ + seccomp_send_sigsys(this_syscall, data); + goto skip; case SECCOMP_RET_ALLOW: return 0; case SECCOMP_RET_KILL: |