6.13-stable review patch. If anyone has any objections, please let me know.
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From: Eyal Birger eyal.birger@gmail.com
commit cf6cb56ef24410fb5308f9655087f1eddf4452e6 upstream.
When attaching uretprobes to processes running inside docker, the attached process is segfaulted when encountering the retprobe.
The reason is that now that uretprobe is a system call the default seccomp filters in docker block it as they only allow a specific set of known syscalls. This is true for other userspace applications which use seccomp to control their syscall surface.
Since uretprobe is a "kernel implementation detail" system call which is not used by userspace application code directly, it is impractical and there's very little point in forcing all userspace applications to explicitly allow it in order to avoid crashing tracked processes.
Pass this systemcall through seccomp without depending on configuration.
Note: uretprobe is currently only x86_64 and isn't expected to ever be supported in i386.
Fixes: ff474a78cef5 ("uprobe: Add uretprobe syscall to speed up return probe") Reported-by: Rafael Buchbinder rafi@rbk.io Closes: https://lore.kernel.org/lkml/CAHsH6Gs3Eh8DFU0wq58c_LF8A4_+o6z456J7BidmcVY2Aq... Link: https://lore.kernel.org/lkml/20250121182939.33d05470@gandalf.local.home/T/#m... Link: https://lore.kernel.org/lkml/20250128145806.1849977-1-eyal.birger@gmail.com/ Cc: stable@vger.kernel.org Signed-off-by: Eyal Birger eyal.birger@gmail.com Link: https://lore.kernel.org/r/20250202162921.335813-2-eyal.birger@gmail.com [kees: minimized changes for easier backporting, tweaked commit log] Signed-off-by: Kees Cook kees@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/seccomp.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
--- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -749,6 +749,15 @@ static bool seccomp_is_const_allow(struc if (WARN_ON_ONCE(!fprog)) return false;
+ /* Our single exception to filtering. */ +#ifdef __NR_uretprobe +#ifdef SECCOMP_ARCH_COMPAT + if (sd->arch == SECCOMP_ARCH_NATIVE) +#endif + if (sd->nr == __NR_uretprobe) + return true; +#endif + for (pc = 0; pc < fprog->len; pc++) { struct sock_filter *insn = &fprog->filter[pc]; u16 code = insn->code; @@ -1023,6 +1032,9 @@ static inline void seccomp_log(unsigned */ static const int mode1_syscalls[] = { __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn, +#ifdef __NR_uretprobe + __NR_uretprobe, +#endif -1, /* negative terminated */ };