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* seccomp: Make syscall skipping and nr changes more consistentAndy Lutomirski2012-10-021-3/+10
| | | | | | | | | | | | | | | | | | | This fixes two issues that could cause incompatibility between kernel versions: - If a tracer uses SECCOMP_RET_TRACE to select a syscall number higher than the largest known syscall, emulate the unknown vsyscall by returning -ENOSYS. (This is unlikely to make a noticeable difference on x86-64 due to the way the system call entry works.) - On x86-64 with vsyscall=emulate, skipped vsyscalls were buggy. This updates the documentation accordingly. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Acked-by: Will Drewry <wad@chromium.org> Signed-off-by: James Morris <james.l.morris@oracle.com>
* seccomp: fix build warnings when there is no CONFIG_SECCOMP_FILTERWill Drewry2012-04-181-4/+9
| | | | | | | | | | | | | | | If both audit and seccomp filter support are disabled, 'ret' is marked as unused. If just seccomp filter support is disabled, data and skip are considered unused. This change fixes those build warnings. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Will Drewry <wad@chromium.org> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: James Morris <james.l.morris@oracle.com>
* ptrace,seccomp: Add PTRACE_SECCOMP supportWill Drewry2012-04-141-0/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This change adds support for a new ptrace option, PTRACE_O_TRACESECCOMP, and a new return value for seccomp BPF programs, SECCOMP_RET_TRACE. When a tracer specifies the PTRACE_O_TRACESECCOMP ptrace option, the tracer will be notified, via PTRACE_EVENT_SECCOMP, for any syscall that results in a BPF program returning SECCOMP_RET_TRACE. The 16-bit SECCOMP_RET_DATA mask of the BPF program return value will be passed as the ptrace_message and may be retrieved using PTRACE_GETEVENTMSG. If the subordinate process is not using seccomp filter, then no system call notifications will occur even if the option is specified. If there is no tracer with PTRACE_O_TRACESECCOMP when SECCOMP_RET_TRACE is returned, the system call will not be executed and an -ENOSYS errno will be returned to userspace. This change adds a dependency on the system call slow path. Any future efforts to use the system call fast path for seccomp filter will need to address this restriction. Signed-off-by: Will Drewry <wad@chromium.org> Acked-by: Eric Paris <eparis@redhat.com> v18: - rebase - comment fatal_signal check - acked-by - drop secure_computing_int comment v17: - ... v16: - update PT_TRACE_MASK to 0xbf4 so that STOP isn't clear on SETOPTIONS call (indan@nul.nu) [note PT_TRACE_MASK disappears in linux-next] v15: - add audit support for non-zero return codes - clean up style (indan@nul.nu) v14: - rebase/nochanges v13: - rebase on to 88ebdda6159ffc15699f204c33feb3e431bf9bdc (Brings back a change to ptrace.c and the masks.) v12: - rebase to linux-next - use ptrace_event and update arch/Kconfig to mention slow-path dependency - drop all tracehook changes and inclusion (oleg@redhat.com) v11: - invert the logic to just make it a PTRACE_SYSCALL accelerator (indan@nul.nu) v10: - moved to PTRACE_O_SECCOMP / PT_TRACE_SECCOMP v9: - n/a v8: - guarded PTRACE_SECCOMP use with an ifdef v7: - introduced Signed-off-by: James Morris <james.l.morris@oracle.com>
* seccomp: Add SECCOMP_RET_TRAPWill Drewry2012-04-141-0/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* seccomp: add SECCOMP_RET_ERRNOWill Drewry2012-04-141-10/+32
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This change adds the SECCOMP_RET_ERRNO as a valid return value from a seccomp filter. Additionally, it makes the first use of the lower 16-bits for storing a filter-supplied errno. 16-bits is more than enough for the errno-base.h calls. Returning errors instead of immediately terminating processes that violate seccomp policy allow for broader use of this functionality for kernel attack surface reduction. For example, a linux container could maintain a whitelist of pre-existing system calls but drop all new ones with errnos. This would keep a logically static attack surface while providing errnos that may allow for graceful failure without the downside of do_exit() on a bad call. This change also changes the signature of __secure_computing. It appears the only direct caller is the arm entry code and it clobbers any possible return value (register) immediately. Signed-off-by: Will Drewry <wad@chromium.org> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Eric Paris <eparis@redhat.com> v18: - fix up comments and rebase - fix bad var name which was fixed in later revs - remove _int() and just change the __secure_computing signature v16-v17: ... v15: - use audit_seccomp and add a skip label. (eparis@redhat.com) - clean up and pad out return codes (indan@nul.nu) v14: - no change/rebase v13: - rebase on to 88ebdda6159ffc15699f204c33feb3e431bf9bdc v12: - move to WARN_ON if filter is NULL (oleg@redhat.com, luto@mit.edu, keescook@chromium.org) - return immediately for filter==NULL (keescook@chromium.org) - change evaluation to only compare the ACTION so that layered errnos don't result in the lowest one being returned. (keeschook@chromium.org) v11: - check for NULL filter (keescook@chromium.org) v10: - change loaders to fn v9: - n/a v8: - update Kconfig to note new need for syscall_set_return_value. - reordered such that TRAP behavior follows on later. - made the for loop a little less indent-y v7: - introduced Signed-off-by: James Morris <james.l.morris@oracle.com>
* seccomp: remove duplicated failure loggingKees Cook2012-04-141-14/+1
| | | | | | | | | | | | | | | This consolidates the seccomp filter error logging path and adds more details to the audit log. Signed-off-by: Will Drewry <wad@chromium.org> Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Eric Paris <eparis@redhat.com> v18: make compat= permanent in the record v15: added a return code to the audit_seccomp path by wad@chromium.org (suggested by eparis@redhat.com) v*: original by keescook@chromium.org Signed-off-by: James Morris <james.l.morris@oracle.com>
* seccomp: add system call filtering using BPFWill Drewry2012-04-141-18/+378
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [This patch depends on luto@mit.edu's no_new_privs patch: https://lkml.org/lkml/2012/1/30/264 The whole series including Andrew's patches can be found here: https://github.com/redpig/linux/tree/seccomp Complete diff here: https://github.com/redpig/linux/compare/1dc65fed...seccomp ] This patch adds support for seccomp mode 2. Mode 2 introduces the ability for unprivileged processes to install system call filtering policy expressed in terms of a Berkeley Packet Filter (BPF) program. This program will be evaluated in the kernel for each system call the task makes and computes a result based on data in the format of struct seccomp_data. A filter program may be installed by calling: struct sock_fprog fprog = { ... }; ... prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &fprog); The return value of the filter program determines if the system call is allowed to proceed or denied. If the first filter program installed allows prctl(2) calls, then the above call may be made repeatedly by a task to further reduce its access to the kernel. All attached programs must be evaluated before a system call will be allowed to proceed. Filter programs will be inherited across fork/clone and execve. However, if the task attaching the filter is unprivileged (!CAP_SYS_ADMIN) the no_new_privs bit will be set on the task. This ensures that unprivileged tasks cannot attach filters that affect privileged tasks (e.g., setuid binary). There are a number of benefits to this approach. A few of which are as follows: - BPF has been exposed to userland for a long time - BPF optimization (and JIT'ing) are well understood - Userland already knows its ABI: system call numbers and desired arguments - No time-of-check-time-of-use vulnerable data accesses are possible. - system call arguments are loaded on access only to minimize copying required for system call policy decisions. Mode 2 support is restricted to architectures that enable HAVE_ARCH_SECCOMP_FILTER. In this patch, the primary dependency is on syscall_get_arguments(). The full desired scope of this feature will add a few minor additional requirements expressed later in this series. Based on discussion, SECCOMP_RET_ERRNO and SECCOMP_RET_TRACE seem to be the desired additional functionality. No architectures are enabled in this patch. Signed-off-by: Will Drewry <wad@chromium.org> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Reviewed-by: Indan Zupancic <indan@nul.nu> Acked-by: Eric Paris <eparis@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org> v18: - rebase to v3.4-rc2 - s/chk/check/ (akpm@linux-foundation.org,jmorris@namei.org) - allocate with GFP_KERNEL|__GFP_NOWARN (indan@nul.nu) - add a comment for get_u32 regarding endianness (akpm@) - fix other typos, style mistakes (akpm@) - added acked-by v17: - properly guard seccomp filter needed headers (leann@ubuntu.com) - tighten return mask to 0x7fff0000 v16: - no change v15: - add a 4 instr penalty when counting a path to account for seccomp_filter size (indan@nul.nu) - drop the max insns to 256KB (indan@nul.nu) - return ENOMEM if the max insns limit has been hit (indan@nul.nu) - move IP checks after args (indan@nul.nu) - drop !user_filter check (indan@nul.nu) - only allow explicit bpf codes (indan@nul.nu) - exit_code -> exit_sig v14: - put/get_seccomp_filter takes struct task_struct (indan@nul.nu,keescook@chromium.org) - adds seccomp_chk_filter and drops general bpf_run/chk_filter user - add seccomp_bpf_load for use by net/core/filter.c - lower max per-process/per-hierarchy: 1MB - moved nnp/capability check prior to allocation (all of the above: indan@nul.nu) v13: - rebase on to 88ebdda6159ffc15699f204c33feb3e431bf9bdc v12: - added a maximum instruction count per path (indan@nul.nu,oleg@redhat.com) - removed copy_seccomp (keescook@chromium.org,indan@nul.nu) - reworded the prctl_set_seccomp comment (indan@nul.nu) v11: - reorder struct seccomp_data to allow future args expansion (hpa@zytor.com) - style clean up, @compat dropped, compat_sock_fprog32 (indan@nul.nu) - do_exit(SIGSYS) (keescook@chromium.org, luto@mit.edu) - pare down Kconfig doc reference. - extra comment clean up v10: - seccomp_data has changed again to be more aesthetically pleasing (hpa@zytor.com) - calling convention is noted in a new u32 field using syscall_get_arch. This allows for cross-calling convention tasks to use seccomp filters. (hpa@zytor.com) - lots of clean up (thanks, Indan!) v9: - n/a v8: - use bpf_chk_filter, bpf_run_filter. update load_fns - Lots of fixes courtesy of indan@nul.nu: -- fix up load behavior, compat fixups, and merge alloc code, -- renamed pc and dropped __packed, use bool compat. -- Added a hidden CONFIG_SECCOMP_FILTER to synthesize non-arch dependencies v7: (massive overhaul thanks to Indan, others) - added CONFIG_HAVE_ARCH_SECCOMP_FILTER - merged into seccomp.c - minimal seccomp_filter.h - no config option (part of seccomp) - no new prctl - doesn't break seccomp on systems without asm/syscall.h (works but arg access always fails) - dropped seccomp_init_task, extra free functions, ... - dropped the no-asm/syscall.h code paths - merges with network sk_run_filter and sk_chk_filter v6: - fix memory leak on attach compat check failure - require no_new_privs || CAP_SYS_ADMIN prior to filter installation. (luto@mit.edu) - s/seccomp_struct_/seccomp_/ for macros/functions (amwang@redhat.com) - cleaned up Kconfig (amwang@redhat.com) - on block, note if the call was compat (so the # means something) v5: - uses syscall_get_arguments (indan@nul.nu,oleg@redhat.com, mcgrathr@chromium.org) - uses union-based arg storage with hi/lo struct to handle endianness. Compromises between the two alternate proposals to minimize extra arg shuffling and account for endianness assuming userspace uses offsetof(). (mcgrathr@chromium.org, indan@nul.nu) - update Kconfig description - add include/seccomp_filter.h and add its installation - (naive) on-demand syscall argument loading - drop seccomp_t (eparis@redhat.com) v4: - adjusted prctl to make room for PR_[SG]ET_NO_NEW_PRIVS - now uses current->no_new_privs (luto@mit.edu,torvalds@linux-foundation.com) - assign names to seccomp modes (rdunlap@xenotime.net) - fix style issues (rdunlap@xenotime.net) - reworded Kconfig entry (rdunlap@xenotime.net) v3: - macros to inline (oleg@redhat.com) - init_task behavior fixed (oleg@redhat.com) - drop creator entry and extra NULL check (oleg@redhat.com) - alloc returns -EINVAL on bad sizing (serge.hallyn@canonical.com) - adds tentative use of "always_unprivileged" as per torvalds@linux-foundation.org and luto@mit.edu v2: - (patch 2 only) Signed-off-by: James Morris <james.l.morris@oracle.com>
* seccomp: audit abnormal end to a process due to seccompEric Paris2012-01-171-0/+2
| | | | | | | | | The audit system likes to collect information about processes that end abnormally (SIGSEGV) as this may me useful intrusion detection information. This patch adds audit support to collect information when seccomp forces a task to exit because of misbehavior in a similar way. Signed-off-by: Eric Paris <eparis@redhat.com>
* x86-64: seccomp: fix 32/64 syscall holeRoland McGrath2009-03-021-3/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On x86-64, a 32-bit process (TIF_IA32) can switch to 64-bit mode with ljmp, and then use the "syscall" instruction to make a 64-bit system call. A 64-bit process make a 32-bit system call with int $0x80. In both these cases under CONFIG_SECCOMP=y, secure_computing() will use the wrong system call number table. The fix is simple: test TS_COMPAT instead of TIF_IA32. Here is an example exploit: /* test case for seccomp circumvention on x86-64 There are two failure modes: compile with -m64 or compile with -m32. The -m64 case is the worst one, because it does "chmod 777 ." (could be any chmod call). The -m32 case demonstrates it was able to do stat(), which can glean information but not harm anything directly. A buggy kernel will let the test do something, print, and exit 1; a fixed kernel will make it exit with SIGKILL before it does anything. */ #define _GNU_SOURCE #include <assert.h> #include <inttypes.h> #include <stdio.h> #include <linux/prctl.h> #include <sys/stat.h> #include <unistd.h> #include <asm/unistd.h> int main (int argc, char **argv) { char buf[100]; static const char dot[] = "."; long ret; unsigned st[24]; if (prctl (PR_SET_SECCOMP, 1, 0, 0, 0) != 0) perror ("prctl(PR_SET_SECCOMP) -- not compiled into kernel?"); #ifdef __x86_64__ assert ((uintptr_t) dot < (1UL << 32)); asm ("int $0x80 # %0 <- %1(%2 %3)" : "=a" (ret) : "0" (15), "b" (dot), "c" (0777)); ret = snprintf (buf, sizeof buf, "result %ld (check mode on .!)\n", ret); #elif defined __i386__ asm (".code32\n" "pushl %%cs\n" "pushl $2f\n" "ljmpl $0x33, $1f\n" ".code64\n" "1: syscall # %0 <- %1(%2 %3)\n" "lretl\n" ".code32\n" "2:" : "=a" (ret) : "0" (4), "D" (dot), "S" (&st)); if (ret == 0) ret = snprintf (buf, sizeof buf, "stat . -> st_uid=%u\n", st[7]); else ret = snprintf (buf, sizeof buf, "result %ld\n", ret); #else # error "not this one" #endif write (1, buf, ret); syscall (__NR_exit, 1); return 2; } Signed-off-by: Roland McGrath <roland@redhat.com> [ I don't know if anybody actually uses seccomp, but it's enabled in at least both Fedora and SuSE kernels, so maybe somebody is. - Linus ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* make seccomp zerocost in scheduleAndrea Arcangeli2007-07-161-0/+3
| | | | | | | | | | | | This follows a suggestion from Chuck Ebbert on how to make seccomp absolutely zerocost in schedule too. The only remaining footprint of seccomp is in terms of the bzImage size that becomes a few bytes (perhaps even a few kbytes) larger, measure it if you care in the embedded. Signed-off-by: Andrea Arcangeli <andrea@cpushare.com> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* move seccomp from /proc to a prctlAndrea Arcangeli2007-07-161-0/+26
| | | | | | | | | | This reduces the memory footprint and it enforces that only the current task can enable seccomp on itself (this is a requirement for a strightforward [modulo preempt ;) ] TIF_NOTSC implementation). Signed-off-by: Andrea Arcangeli <andrea@cpushare.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Linux-2.6.12-rc2v2.6.12-rc2Linus Torvalds2005-04-161-0/+56
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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