| Message ID | 20250209220515.2554058-1-jolsa@kernel.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [bpf-next] uprobes: Harden uretprobe syscall trampoline check | expand |
On 02/09, Jiri Olsa wrote: > > [1] https://lore.kernel.org/bpf/202502081235.5A6F352985@keescook/T/#m9d416df341b8fbc11737dacbcd29f0054413cbbf > Cc: Kees Cook <kees@kernel.org> > Cc: Eyal Birger <eyal.birger@gmail.com> > Cc: stable@vger.kernel.org > Reported-by: Jann Horn <jannh@google.com> > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > --- > arch/x86/kernel/uprobes.c | 14 +++++++++----- > 1 file changed, 9 insertions(+), 5 deletions(-) Reviewed-by: Oleg Nesterov <oleg@redhat.com>
On Sun, Feb 9, 2025 at 2:05 PM Jiri Olsa <jolsa@kernel.org> wrote: > > Jann reported [1] possible issue when trampoline_check_ip returns > address near the bottom of the address space that is allowed to > call into the syscall if uretprobes are not set up. > > Though the mmap minimum address restrictions will typically prevent > creating mappings there, let's make sure uretprobe syscall checks > for that. > > [1] https://lore.kernel.org/bpf/202502081235.5A6F352985@keescook/T/#m9d416df341b8fbc11737dacbcd29f0054413cbbf > Cc: Kees Cook <kees@kernel.org> > Cc: Eyal Birger <eyal.birger@gmail.com> > Cc: stable@vger.kernel.org > Reported-by: Jann Horn <jannh@google.com> > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > --- > arch/x86/kernel/uprobes.c | 14 +++++++++----- > 1 file changed, 9 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c > index 5a952c5ea66b..109d6641a1b3 100644 > --- a/arch/x86/kernel/uprobes.c > +++ b/arch/x86/kernel/uprobes.c > @@ -357,19 +357,23 @@ void *arch_uprobe_trampoline(unsigned long *psize) > return &insn; > } > > -static unsigned long trampoline_check_ip(void) > +static unsigned long trampoline_check_ip(unsigned long tramp) > { > - unsigned long tramp = uprobe_get_trampoline_vaddr(); > - > return tramp + (uretprobe_syscall_check - uretprobe_trampoline_entry); > } > > SYSCALL_DEFINE0(uretprobe) > { > struct pt_regs *regs = task_pt_regs(current); > - unsigned long err, ip, sp, r11_cx_ax[3]; > + unsigned long err, ip, sp, r11_cx_ax[3], tramp; > + > + /* If there's no trampoline, we are called from wrong place. */ > + tramp = uprobe_get_trampoline_vaddr(); > + if (tramp == -1) slight nit: mixing -1 and unsigned long looks sloppy. Maybe let's add something like #define UPROBE_NO_TRAMPOLINE_VADDR ((unsigned long)-1) and return that from uprobe_get_trampoline_vaddr()? > + goto sigill; > > - if (regs->ip != trampoline_check_ip()) > + /* Make sure the ip matches the only allowed sys_uretprobe caller. */ > + if (regs->ip != trampoline_check_ip(tramp)) > goto sigill; > > err = copy_from_user(r11_cx_ax, (void __user *)regs->sp, sizeof(r11_cx_ax)); > -- > 2.48.1 >
On Sun, Feb 09, 2025 at 11:05:15PM +0100, Jiri Olsa wrote: > Jann reported [1] possible issue when trampoline_check_ip returns > address near the bottom of the address space that is allowed to > call into the syscall if uretprobes are not set up. > > Though the mmap minimum address restrictions will typically prevent > creating mappings there, let's make sure uretprobe syscall checks > for that. > > [1] https://lore.kernel.org/bpf/202502081235.5A6F352985@keescook/T/#m9d416df341b8fbc11737dacbcd29f0054413cbbf > Cc: Kees Cook <kees@kernel.org> > Cc: Eyal Birger <eyal.birger@gmail.com> > Cc: stable@vger.kernel.org > Reported-by: Jann Horn <jannh@google.com> > Signed-off-by: Jiri Olsa <jolsa@kernel.org> Thanks for this! Reviewed-by: Kees Cook <kees@kernel.org>
On Mon, Feb 10, 2025 at 09:26:53AM -0800, Andrii Nakryiko wrote: > On Sun, Feb 9, 2025 at 2:05 PM Jiri Olsa <jolsa@kernel.org> wrote: > > > > Jann reported [1] possible issue when trampoline_check_ip returns > > address near the bottom of the address space that is allowed to > > call into the syscall if uretprobes are not set up. > > > > Though the mmap minimum address restrictions will typically prevent > > creating mappings there, let's make sure uretprobe syscall checks > > for that. > > > > [1] https://lore.kernel.org/bpf/202502081235.5A6F352985@keescook/T/#m9d416df341b8fbc11737dacbcd29f0054413cbbf > > Cc: Kees Cook <kees@kernel.org> > > Cc: Eyal Birger <eyal.birger@gmail.com> > > Cc: stable@vger.kernel.org > > Reported-by: Jann Horn <jannh@google.com> > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > > --- > > arch/x86/kernel/uprobes.c | 14 +++++++++----- > > 1 file changed, 9 insertions(+), 5 deletions(-) > > > > diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c > > index 5a952c5ea66b..109d6641a1b3 100644 > > --- a/arch/x86/kernel/uprobes.c > > +++ b/arch/x86/kernel/uprobes.c > > @@ -357,19 +357,23 @@ void *arch_uprobe_trampoline(unsigned long *psize) > > return &insn; > > } > > > > -static unsigned long trampoline_check_ip(void) > > +static unsigned long trampoline_check_ip(unsigned long tramp) > > { > > - unsigned long tramp = uprobe_get_trampoline_vaddr(); > > - > > return tramp + (uretprobe_syscall_check - uretprobe_trampoline_entry); > > } > > > > SYSCALL_DEFINE0(uretprobe) > > { > > struct pt_regs *regs = task_pt_regs(current); > > - unsigned long err, ip, sp, r11_cx_ax[3]; > > + unsigned long err, ip, sp, r11_cx_ax[3], tramp; > > + > > + /* If there's no trampoline, we are called from wrong place. */ > > + tramp = uprobe_get_trampoline_vaddr(); > > + if (tramp == -1) > > slight nit: mixing -1 and unsigned long looks sloppy. Maybe let's add > something like > > #define UPROBE_NO_TRAMPOLINE_VADDR ((unsigned long)-1) > > and return that from uprobe_get_trampoline_vaddr()? ok, will add that thanks, jirka > > > + goto sigill; > > > > - if (regs->ip != trampoline_check_ip()) > > + /* Make sure the ip matches the only allowed sys_uretprobe caller. */ > > + if (regs->ip != trampoline_check_ip(tramp)) > > goto sigill; > > > > err = copy_from_user(r11_cx_ax, (void __user *)regs->sp, sizeof(r11_cx_ax)); > > -- > > 2.48.1 > >
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index 5a952c5ea66b..109d6641a1b3 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -357,19 +357,23 @@ void *arch_uprobe_trampoline(unsigned long *psize) return &insn; } -static unsigned long trampoline_check_ip(void) +static unsigned long trampoline_check_ip(unsigned long tramp) { - unsigned long tramp = uprobe_get_trampoline_vaddr(); - return tramp + (uretprobe_syscall_check - uretprobe_trampoline_entry); } SYSCALL_DEFINE0(uretprobe) { struct pt_regs *regs = task_pt_regs(current); - unsigned long err, ip, sp, r11_cx_ax[3]; + unsigned long err, ip, sp, r11_cx_ax[3], tramp; + + /* If there's no trampoline, we are called from wrong place. */ + tramp = uprobe_get_trampoline_vaddr(); + if (tramp == -1) + goto sigill; - if (regs->ip != trampoline_check_ip()) + /* Make sure the ip matches the only allowed sys_uretprobe caller. */ + if (regs->ip != trampoline_check_ip(tramp)) goto sigill; err = copy_from_user(r11_cx_ax, (void __user *)regs->sp, sizeof(r11_cx_ax));
Jann reported [1] possible issue when trampoline_check_ip returns address near the bottom of the address space that is allowed to call into the syscall if uretprobes are not set up. Though the mmap minimum address restrictions will typically prevent creating mappings there, let's make sure uretprobe syscall checks for that. [1] https://lore.kernel.org/bpf/202502081235.5A6F352985@keescook/T/#m9d416df341b8fbc11737dacbcd29f0054413cbbf Cc: Kees Cook <kees@kernel.org> Cc: Eyal Birger <eyal.birger@gmail.com> Cc: stable@vger.kernel.org Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Jiri Olsa <jolsa@kernel.org> --- arch/x86/kernel/uprobes.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-)