From 50fa3001ce25e221ca2e54564b5589d29c4bed19 Mon Sep 17 00:00:00 2001 From: Sergio Durigan Junior Date: Thu, 26 Sep 2019 14:24:30 -0400 Subject: [PATCH] Revert "Improve ptrace-error detection on Linux targets" This reverts commit 381beca6146ac68b57edf47d28cdb335fbd11635. The patch hasn't been fully reviewed yet, and Pedro would like to see more fixes. --- gdb/ChangeLog | 45 --------- gdb/doc/ChangeLog | 5 - gdb/doc/gdb.texinfo | 143 --------------------------- gdb/gdbserver/ChangeLog | 14 --- gdb/gdbserver/linux-low.c | 9 +- gdb/gdbserver/server.c | 14 +-- gdb/gdbserver/thread-db.c | 2 +- gdb/gdbsupport/gdb-dlfcn.h | 4 +- gdb/inf-ptrace.c | 17 +--- gdb/inf-ptrace.h | 10 -- gdb/linux-nat.c | 9 +- gdb/nat/fork-inferior.c | 4 +- gdb/nat/fork-inferior.h | 7 +- gdb/nat/linux-ptrace.c | 192 ++----------------------------------- gdb/nat/linux-ptrace.h | 27 ++---- gdb/remote.c | 16 +--- 16 files changed, 31 insertions(+), 487 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 37626bdd1e..f323cf6b14 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,48 +1,3 @@ -2019-09-26 Sergio Durigan Junior - Jan Kratochvil - Pedro Alves - - * gdbsupport/gdb-dlfcn.h (gdb_dlopen): Update comment and - mention that the function throws an error. - * inf-ptrace.c (default_inf_ptrace_me_fail_reason): New - function. - (inf_ptrace_me_fail_reason): New variable. - (inf_ptrace_me): Update call to 'trace_start_error_with_name'. - * inf-ptrace.h (inf_ptrace_me_fail_reason): New variable. - * linux-nat.c (attach_proc_task_lwp_callback): Call - 'linux_ptrace_attach_fail_reason_lwp'. - (linux_nat_target::attach): Update call to - 'linux_ptrace_attach_fail_reason'. - (_initialize_linux_nat): Set 'inf_ptrace_me_fail_reason'. - * nat/fork-inferior.c (trace_start_error_with_name): Add - optional 'append' argument. - * nat/fork-inferior.h (trace_start_error_with_name): Update - prototype. - * nat/linux-ptrace.c: Include "gdbsupport/gdb-dlfcn.h", - "gdbsupport/filestuff.h" and "nat/fork-inferior.h". - (selinux_ftype): New typedef. - (linux_ptrace_restricted_fail_reason): New function. - (linux_ptrace_attach_fail_reason_1): New function. - (linux_ptrace_attach_fail_reason): Change first argument type - from 'ptid_t' to 'pid_t'. Call - 'linux_ptrace_attach_fail_reason_1' and - 'linux_ptrace_restricted_fail_reason'. - (linux_ptrace_attach_fail_reason_lwp): New function. - (linux_ptrace_me_fail_reason): New function. - (errno_pipe): New variable. - (linux_fork_to_function): Initialize pipe before forking. - (linux_child_function): Deal with errno-passing from child. - Handle ptrace error. - (linux_check_child_ptrace_errno): New function. - (linux_check_child_ptrace_errno): Call - 'linux_check_child_ptrace_errno'. - * nat/linux-ptrace.h (linux_ptrace_attach_fail_reason): Update - prototype. - (linux_ptrace_attach_fail_reason_lwp): New prototype. - (linux_ptrace_me_fail_reason): New prototype. - * remote.c (extended_remote_target::attach): Handle error - message passed by the server when attach fails. - 2019-09-26 Christian Biesinger * blockframe.c (find_pc_partial_function): Change return type to bool. diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog index 003c8c2ffe..0a10fa3fad 100644 --- a/gdb/doc/ChangeLog +++ b/gdb/doc/ChangeLog @@ -1,8 +1,3 @@ -2019-09-26 Sergio Durigan Junior - - * gdb.texinfo (Linux kernel ptrace restrictions): New appendix - section. - 2019-09-20 Ulrich Weigand * doc/gdb.texinfo (Remote Configuration): Remove documentation for diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo index e7b5b18f2b..f2713c0396 100644 --- a/gdb/doc/gdb.texinfo +++ b/gdb/doc/gdb.texinfo @@ -182,9 +182,6 @@ software in general. We will miss him. @value{GDBN} * Operating System Information:: Getting additional information from the operating system -* Linux kernel ptrace restrictions:: Restrictions sometimes - imposed by the Linux - kernel on @code{ptrace} * Trace File Format:: GDB trace file format * Index Section Format:: .gdb_index section format * Man Pages:: Manual pages @@ -44668,146 +44665,6 @@ should contain a comma-separated list of cores that this process is running on. Target may provide additional columns, which @value{GDBN} currently ignores. -@node Linux kernel ptrace restrictions -@appendix Linux kernel @code{ptrace} restrictions -@cindex linux kernel ptrace restrictions, attach - -The @code{ptrace} system call is used by @value{GDBN} and -@code{gdbserver} on GNU/Linux to, among other things, attach to a new -or existing inferior in order to start debugging it. Due to security -concerns, some distributions and vendors disable or severely restrict -the ability to perform these operations, which can make @value{GDBN} -or @code{gdbserver} malfunction. In this section, we will expand on -how this malfunction can manifest itself, and how to modify the -system's settings in order to be able to use @value{GDBN} and -@code{gdbserver} properly. - -@menu -* The error message:: The error message displayed when the - system prevents @value{GDBN} - or @code{gdbserver} from using - @code{ptrace} -* SELinux's deny_ptrace:: SELinux and the @code{deny_ptrace} option -* Yama's ptrace_scope:: Yama and the @code{ptrace_scope} setting -* Docker and seccomp:: Docker and the @code{seccomp} - infrastructure -@end menu - -@node The error message -@appendixsection The error message - -When the system prevents @value{GDBN} or @code{gdbserver} from using -the @code{ptrace} system call, you will likely see a descriptive error -message explaining what is wrong and how to attempt to fix the -problem. For example, when SELinux's @code{deny_ptrace} option is -enabled, you can see: - -@smallexample -$ gdb program -... -(@value{GDBP}) run -Starting program: program -warning: Could not trace the inferior process. -Error: -warning: ptrace: Permission denied -The SELinux 'deny_ptrace' option is enabled and preventing @value{GDBN} -from using 'ptrace'. You can disable it by executing (as root): - - setsebool deny_ptrace off - -If you are debugging the inferior remotely, the instruction(s) above must -be performed in the target system (e.g., where GDBserver is running). -During startup program exited with code 127. -(@value{GDBP}) -@end smallexample - -Sometimes, it may not be possible to acquire the necessary data to -determine the root cause of the failure. In this case, you will see a -generic error message pointing you to this section: - -@smallexample -$ gdb program -... -Starting program: program -warning: Could not trace the inferior process. -Error: -warning: ptrace: Permission denied -There might be restrictions preventing ptrace from working. Please see -the appendix "Linux kernel ptrace restrictions" in the GDB documentation -for more details. -During startup program exited with code 127. -(@value{GDBP}) -@end smallexample - -@node SELinux's deny_ptrace -@appendixsection SELinux's @code{deny_ptrace} -@cindex SELinux -@cindex deny_ptrace - -If you are using SELinux, you might want to check whether the -@code{deny_ptrace} option is enabled by doing: - -@smallexample -$ getsebool deny_ptrace -deny_ptrace --> on -@end smallexample - -If the option is enabled, you can disable it by doing, as root: - -@smallexample -# setsebool deny_ptrace off -@end smallexample - -The option will be disabled until the next reboot. If you would like -to disable it permanently, you can do (as root): - -@smallexample -# setsebool -P deny_ptrace off -@end smallexample - -@node Yama's ptrace_scope -@appendixsection Yama's @code{ptrace_scope} -@cindex yama, ptrace_scope - -If your system has Yama enabled, you might want to check whether the -@code{ptrace_scope} setting is enabled by checking the value of -@file{/proc/sys/kernel/yama/ptrace_scope}: - -@smallexample -$ cat /proc/sys/kernel/yama/ptrace_scope -0 -@end smallexample - -If you see anything other than @code{0}, @value{GDBN} or -@code{gdbserver} can be affected by it. You can temporarily disable -the feature by doing, as root: - -@smallexample -# sysctl kernel.yama.ptrace_scope=0 -kernel.yama.ptrace_scope = 0 -@end smallexample - -You can make this permanent by doing, as root: - -@smallexample -# sysctl -w kernel.yama.ptrace_scope=0 -kernel.yama.ptrace_scope = 0 -@end smallexample - -@node Docker and seccomp -@appendixsection Docker and @code{seccomp} -@cindex docker, seccomp - -If you are using Docker (@uref{https://www.docker.com/}) containers, -you will probably have to disable its @code{seccomp} protections in -order to be able to use @value{GDBN} or @code{gdbserver}. To do that, -you can use the options @code{--cap-add=SYS_PTRACE --security-opt -seccomp=unconfined} when invoking Docker: - -@smallexample -$ docker run --cap-add=SYS_PTRACE --security-opt seccomp=unconfined -@end smallexample - @node Trace File Format @appendix Trace File Format @cindex trace file format diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog index e60980dc56..c0c6f51a06 100644 --- a/gdb/gdbserver/ChangeLog +++ b/gdb/gdbserver/ChangeLog @@ -1,17 +1,3 @@ -2019-09-26 Sergio Durigan Junior - Pedro Alves - - * linux-low.c (linux_ptrace_fun): Call - 'linux_ptrace_me_fail_reason'. - (attach_proc_task_lwp_callback): Call - 'linux_ptrace_attach_fail_reason_lwp'. - (linux_attach): Call 'linux_ptrace_attach_fail_reason'. - * server.c (handle_v_attach): Use try..catch when calling - 'attach_inferior', and send an error message to the client - when needed. - * thread-db.c (attach_thread): Call - 'linux_ptrace_attach_fail_reason_lwp'. - 2019-09-20 Christian Biesinger * debug.c (debug_threads): Remove comment in favor of the header. diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c index c0e15c122f..d64c3641ff 100644 --- a/gdb/gdbserver/linux-low.c +++ b/gdb/gdbserver/linux-low.c @@ -967,8 +967,7 @@ linux_ptrace_fun () { if (ptrace (PTRACE_TRACEME, 0, (PTRACE_TYPE_ARG3) 0, (PTRACE_TYPE_ARG4) 0) < 0) - trace_start_error_with_name ("ptrace", - linux_ptrace_me_fail_reason (errno).c_str ()); + trace_start_error_with_name ("ptrace"); if (setpgid (0, 0) < 0) trace_start_error_with_name ("setpgid"); @@ -1166,7 +1165,7 @@ attach_proc_task_lwp_callback (ptid_t ptid) else if (err != 0) { std::string reason - = linux_ptrace_attach_fail_reason_lwp (ptid, err); + = linux_ptrace_attach_fail_reason_string (ptid, err); warning (_("Cannot attach to lwp %d: %s"), lwpid, reason.c_str ()); } @@ -1198,8 +1197,8 @@ linux_attach (unsigned long pid) { remove_process (proc); - std::string reason = linux_ptrace_attach_fail_reason (pid, err); - error (_("Cannot attach to process %ld: %s"), pid, reason.c_str ()); + std::string reason = linux_ptrace_attach_fail_reason_string (ptid, err); + error ("Cannot attach to process %ld: %s", pid, reason.c_str ()); } /* Don't ignore the initial SIGSTOP if we just attached to this diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c index 976ecbd2df..67e8e3e54d 100644 --- a/gdb/gdbserver/server.c +++ b/gdb/gdbserver/server.c @@ -2893,21 +2893,9 @@ handle_v_attach (char *own_buf) { client_state &cs = get_client_state (); int pid; - int ret; pid = strtol (own_buf + 8, NULL, 16); - - try - { - ret = attach_inferior (pid); - } - catch (const gdb_exception_error &e) - { - snprintf (own_buf, PBUFSIZ, "E.%s", e.what ()); - return 0; - } - - if (pid != 0 && ret == 0) + if (pid != 0 && attach_inferior (pid) == 0) { /* Don't report shared library events after attaching, even if some libraries are preloaded. GDB will always poll the diff --git a/gdb/gdbserver/thread-db.c b/gdb/gdbserver/thread-db.c index e3acf83850..c6b43a06cc 100644 --- a/gdb/gdbserver/thread-db.c +++ b/gdb/gdbserver/thread-db.c @@ -224,7 +224,7 @@ attach_thread (const td_thrhandle_t *th_p, td_thrinfo_t *ti_p) err = linux_attach_lwp (ptid); if (err != 0) { - std::string reason = linux_ptrace_attach_fail_reason_lwp (ptid, err); + std::string reason = linux_ptrace_attach_fail_reason_string (ptid, err); warning ("Could not attach to thread %ld (LWP %d): %s", (unsigned long) ti_p->ti_tid, ti_p->ti_lid, reason.c_str ()); diff --git a/gdb/gdbsupport/gdb-dlfcn.h b/gdb/gdbsupport/gdb-dlfcn.h index e933b7a473..6a39d38941 100644 --- a/gdb/gdbsupport/gdb-dlfcn.h +++ b/gdb/gdbsupport/gdb-dlfcn.h @@ -32,8 +32,8 @@ struct dlclose_deleter typedef std::unique_ptr gdb_dlhandle_up; /* Load the dynamic library file named FILENAME, and return a handle - for that dynamic library. Throw an error if the loading fails for - any reason. */ + for that dynamic library. Return NULL if the loading fails for any + reason. */ gdb_dlhandle_up gdb_dlopen (const char *filename); diff --git a/gdb/inf-ptrace.c b/gdb/inf-ptrace.c index b792af00d1..4a8e732373 100644 --- a/gdb/inf-ptrace.c +++ b/gdb/inf-ptrace.c @@ -94,20 +94,6 @@ inf_ptrace_target::remove_fork_catchpoint (int pid) #endif /* PT_GET_PROCESS_STATE */ -/* Default method for "inf_ptrace_me_fail_reason", which returns an - empty string. */ - -static std::string -default_inf_ptrace_me_fail_reason (int err) -{ - return {}; -} - -/* See inf-ptrace.h. */ - -std::string (*inf_ptrace_me_fail_reason) (int err) - = default_inf_ptrace_me_fail_reason; - /* Prepare to be traced. */ static void @@ -115,8 +101,7 @@ inf_ptrace_me (void) { /* "Trace me, Dr. Memory!" */ if (ptrace (PT_TRACE_ME, 0, (PTRACE_TYPE_ARG3) 0, 0) < 0) - trace_start_error_with_name ("ptrace", - inf_ptrace_me_fail_reason (errno).c_str ()); + trace_start_error_with_name ("ptrace"); } /* Start a new inferior Unix child process. EXEC_FILE is the file to diff --git a/gdb/inf-ptrace.h b/gdb/inf-ptrace.h index 7cdab9af89..98b5d2e09e 100644 --- a/gdb/inf-ptrace.h +++ b/gdb/inf-ptrace.h @@ -83,14 +83,4 @@ protected: extern pid_t get_ptrace_pid (ptid_t); -/* Pointer to "inf_ptrace_me_fail_reason", which implements a function - that can be called by "inf_ptrace_me" in order to obtain the reason - for a ptrace failure. ERR is the ERRNO value set by the failing - ptrace call. - - This pointer can be overriden by targets that want to personalize - the error message printed when ptrace fails (see linux-nat.c, for - example). */ -extern std::string (*inf_ptrace_me_fail_reason) (int err); - #endif diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c index 2c7ded7043..cd5cf1830d 100644 --- a/gdb/linux-nat.c +++ b/gdb/linux-nat.c @@ -1132,7 +1132,7 @@ attach_proc_task_lwp_callback (ptid_t ptid) else { std::string reason - = linux_ptrace_attach_fail_reason_lwp (ptid, err); + = linux_ptrace_attach_fail_reason_string (ptid, err); warning (_("Cannot attach to lwp %d: %s"), lwpid, reason.c_str ()); @@ -1187,9 +1187,8 @@ linux_nat_target::attach (const char *args, int from_tty) } catch (const gdb_exception_error &ex) { - int saved_errno = errno; pid_t pid = parse_pid_to_attach (args); - std::string reason = linux_ptrace_attach_fail_reason (pid, saved_errno); + std::string reason = linux_ptrace_attach_fail_reason (pid); if (!reason.empty ()) throw_error (ex.error, "warning: %s\n%s", reason.c_str (), @@ -4568,10 +4567,6 @@ Enables printf debugging output."), sigemptyset (&blocked_mask); lwp_lwpid_htab_create (); - - /* Set the proper function to generate a message when ptrace - fails. */ - inf_ptrace_me_fail_reason = linux_ptrace_me_fail_reason; } diff --git a/gdb/nat/fork-inferior.c b/gdb/nat/fork-inferior.c index 2ead4a4858..355e9bef43 100644 --- a/gdb/nat/fork-inferior.c +++ b/gdb/nat/fork-inferior.c @@ -591,7 +591,7 @@ trace_start_error (const char *fmt, ...) /* See nat/fork-inferior.h. */ void -trace_start_error_with_name (const char *string, const char *append) +trace_start_error_with_name (const char *string) { - trace_start_error ("%s: %s%s", string, safe_strerror (errno), append); + trace_start_error ("%s: %s", string, safe_strerror (errno)); } diff --git a/gdb/nat/fork-inferior.h b/gdb/nat/fork-inferior.h index 405f2cf548..065496c382 100644 --- a/gdb/nat/fork-inferior.h +++ b/gdb/nat/fork-inferior.h @@ -98,10 +98,9 @@ extern void trace_start_error (const char *fmt, ...) ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 2); /* Like "trace_start_error", but the error message is constructed by - combining STRING with the system error message for errno, and - (optionally) with APPEND. This function does not return. */ -extern void trace_start_error_with_name (const char *string, - const char *append = "") + combining STRING with the system error message for errno. This + function does not return. */ +extern void trace_start_error_with_name (const char *string) ATTRIBUTE_NORETURN; #endif /* NAT_FORK_INFERIOR_H */ diff --git a/gdb/nat/linux-ptrace.c b/gdb/nat/linux-ptrace.c index 8a048d2ec9..c1ebc0a032 100644 --- a/gdb/nat/linux-ptrace.c +++ b/gdb/nat/linux-ptrace.c @@ -21,9 +21,6 @@ #include "linux-procfs.h" #include "linux-waitpid.h" #include "gdbsupport/buffer.h" -#include "gdbsupport/gdb-dlfcn.h" -#include "nat/fork-inferior.h" -#include "gdbsupport/filestuff.h" #ifdef HAVE_SYS_PROCFS_H #include #endif @@ -33,94 +30,11 @@ of 0 means there are no supported features. */ static int supported_ptrace_options = -1; -typedef int (*selinux_ftype) (const char *); +/* Find all possible reasons we could fail to attach PID and return these + as a string. An empty string is returned if we didn't find any reason. */ -/* Helper function which checks if ptrace is probably restricted - (i.e., if ERR is either EACCES or EPERM), and returns a string with - possible workarounds. */ - -static std::string -linux_ptrace_restricted_fail_reason (int err) -{ - if (err != EACCES && err != EPERM) - { - /* It just makes sense to perform the checks below if errno was - either EACCES or EPERM. */ - return {}; - } - - std::string ret; - gdb_dlhandle_up handle; - - try - { - handle = gdb_dlopen ("libselinux.so.1"); - } - catch (const gdb_exception_error &e) - { - handle.reset (nullptr); - } - - if (handle != nullptr) - { - selinux_ftype selinux_get_bool - = (selinux_ftype) gdb_dlsym (handle, "security_get_boolean_active"); - - if (selinux_get_bool != NULL - && (*selinux_get_bool) ("deny_ptrace") == 1) - string_appendf (ret, - _("\n\ -The SELinux 'deny_ptrace' option is enabled and preventing GDB\n\ -from using 'ptrace'. You can disable it by executing (as root):\n\ -\n\ - setsebool deny_ptrace off\n")); - } - - gdb_file_up yama_ptrace_scope - = gdb_fopen_cloexec ("/proc/sys/kernel/yama/ptrace_scope", "r"); - - if (yama_ptrace_scope != nullptr) - { - char yama_scope = fgetc (yama_ptrace_scope.get ()); - - if (yama_scope != '0') - string_appendf (ret, - _("\n\ -The Linux kernel's Yama ptrace scope is in effect, which can prevent\n\ -GDB from using 'ptrace'. You can disable it by executing (as root):\n\ -\n\ - echo 0 > /proc/sys/kernel/yama/ptrace_scope\n")); - } - - if (ret.empty ()) - { - /* It wasn't possible to determine the exact reason for the - ptrace error. Let's just emit a generic error message - pointing the user to our documentation, where she can find - instructions on how to try to diagnose the problem. */ - ret = _("\n\ -There might be restrictions preventing ptrace from working. Please see\n\ -the appendix \"Linux kernel ptrace restrictions\" in the GDB documentation\n\ -for more details."); - } - - /* The user may be debugging remotely, so we have to warn that - the instructions above should be performed in the target. */ - string_appendf (ret, - _("\n\ -If you are debugging the inferior remotely, the ptrace restriction(s) must\n\ -be disabled in the target system (e.g., where GDBserver is running).")); - - return ret; -} - -/* Find all possible reasons we could fail to attach PID and return - these as a string. An empty string is returned if we didn't find - any reason. Helper for linux_ptrace_attach_fail_reason and - linux_ptrace_attach_fail_reason_lwp. */ - -static std::string -linux_ptrace_attach_fail_reason_1 (pid_t pid) +std::string +linux_ptrace_attach_fail_reason (pid_t pid) { pid_t tracerpid = linux_proc_get_tracerpid_nowarn (pid); std::string result; @@ -142,24 +56,10 @@ linux_ptrace_attach_fail_reason_1 (pid_t pid) /* See linux-ptrace.h. */ std::string -linux_ptrace_attach_fail_reason (pid_t pid, int err) -{ - std::string result = linux_ptrace_attach_fail_reason_1 (pid); - std::string ptrace_restrict = linux_ptrace_restricted_fail_reason (err); - - if (!ptrace_restrict.empty ()) - result += "\n" + ptrace_restrict; - - return result; -} - -/* See linux-ptrace.h. */ - -std::string -linux_ptrace_attach_fail_reason_lwp (ptid_t ptid, int err) +linux_ptrace_attach_fail_reason_string (ptid_t ptid, int err) { long lwpid = ptid.lwp (); - std::string reason = linux_ptrace_attach_fail_reason_1 (lwpid); + std::string reason = linux_ptrace_attach_fail_reason (lwpid); if (!reason.empty ()) return string_printf ("%s (%d), %s", safe_strerror (err), err, @@ -168,14 +68,6 @@ linux_ptrace_attach_fail_reason_lwp (ptid_t ptid, int err) return string_printf ("%s (%d)", safe_strerror (err), err); } -/* See linux-ptrace.h. */ - -std::string -linux_ptrace_me_fail_reason (int err) -{ - return linux_ptrace_restricted_fail_reason (err); -} - #if defined __i386__ || defined __x86_64__ /* Address of the 'ret' instruction in asm code block below. */ @@ -365,12 +257,6 @@ linux_ptrace_test_ret_to_nx (void) #endif /* defined __i386__ || defined __x86_64__ */ } -/* If the PTRACE_TRACEME call on linux_child_function errors, we need - to be able to send ERRNO back to the parent so that it can check - whether there are restrictions in place preventing ptrace from - working. We do that with a pipe. */ -static int errno_pipe[2]; - /* Helper function to fork a process and make the child process call the function FUNCTION, passing CHILD_STACK as parameter. @@ -387,11 +273,6 @@ linux_fork_to_function (gdb_byte *child_stack, int (*function) (void *)) /* Sanity check the function pointer. */ gdb_assert (function != NULL); - /* Create the pipe that will be used by the child to pass ERRNO - after the PTRACE_TRACEME call. */ - if (pipe (errno_pipe) != 0) - trace_start_error_with_name ("pipe"); - #if defined(__UCLIBC__) && defined(HAS_NOMMU) #define STACK_SIZE 4096 @@ -440,21 +321,7 @@ linux_grandchild_function (void *child_stack) static int linux_child_function (void *child_stack) { - /* Close read end. */ - close (errno_pipe[0]); - - int ret = ptrace (PTRACE_TRACEME, 0, (PTRACE_TYPE_ARG3) 0, - (PTRACE_TYPE_ARG4) 0); - int ptrace_errno = errno; - - /* Write ERRNO to the pipe, even if it's zero, and close the writing - end of the pipe. */ - write (errno_pipe[1], &ptrace_errno, sizeof (ptrace_errno)); - close (errno_pipe[1]); - - if (ret != 0) - _exit (0); - + ptrace (PTRACE_TRACEME, 0, (PTRACE_TYPE_ARG3) 0, (PTRACE_TYPE_ARG4) 0); kill (getpid (), SIGSTOP); /* Fork a grandchild. */ @@ -469,48 +336,6 @@ static void linux_test_for_tracesysgood (int child_pid); static void linux_test_for_tracefork (int child_pid); static void linux_test_for_exitkill (int child_pid); -/* Helper function to wait for the child to send us the ptrace ERRNO, - and check if it's OK. */ - -static void -linux_check_child_ptrace_errno () -{ - int child_errno; - fd_set rset; - struct timeval timeout; - - /* Close the writing end of the pipe. */ - close (errno_pipe[1]); - - FD_ZERO (&rset); - FD_SET (errno_pipe[0], &rset); - - /* One second should be plenty of time to wait for the child's - reply. */ - timeout.tv_sec = 1; - timeout.tv_usec = 0; - - int ret = select (errno_pipe[0] + 1, &rset, NULL, NULL, &timeout); - - if (ret < 0) - trace_start_error_with_name ("select"); - else if (ret == 0) - error (_("Timeout while waiting for child's ptrace errno")); - else - read (errno_pipe[0], &child_errno, sizeof (child_errno)); - - if (child_errno != 0) - { - /* The child can't use PTRACE_TRACEME. We just bail out. */ - std::string reason = linux_ptrace_restricted_fail_reason (child_errno); - - errno = child_errno; - trace_start_error_with_name ("ptrace", reason.c_str ()); - } - - close (errno_pipe[0]); -} - /* Determine ptrace features available on this target. */ void @@ -527,9 +352,6 @@ linux_check_ptrace_features (void) reporting. */ child_pid = linux_fork_to_function (NULL, linux_child_function); - /* Check if the child can successfully use ptrace. */ - linux_check_child_ptrace_errno (); - ret = my_waitpid (child_pid, &status, 0); if (ret == -1) perror_with_name (("waitpid")); diff --git a/gdb/nat/linux-ptrace.h b/gdb/nat/linux-ptrace.h index 90afb60f34..fd2f12a342 100644 --- a/gdb/nat/linux-ptrace.h +++ b/gdb/nat/linux-ptrace.h @@ -176,27 +176,12 @@ struct buffer; # define TRAP_HWBKPT 4 #endif -/* Find all possible reasons we could fail to attach PID and return - these as a string. An empty string is returned if we didn't find - any reason. If ERR is EACCES or EPERM, we also add a warning about - possible restrictions to use ptrace. */ -extern std::string linux_ptrace_attach_fail_reason (pid_t pid, int err); - -/* Find all possible reasons we could have failed to attach to PID's - LWPID and return them as a string. ERR is the error PTRACE_ATTACH - failed with (an errno). Unlike linux_ptrace_attach_fail_reason, - this function should be used when attaching to an LWP other than - the leader; it does not warn about ptrace restrictions. */ -extern std::string linux_ptrace_attach_fail_reason_lwp (ptid_t pid, int err); - -/* When the call to 'ptrace (PTRACE_TRACEME...' fails, and we have - already forked, this function can be called in order to try to - obtain the reason why ptrace failed. ERR should be the ERRNO value - returned by ptrace. - - This function will return a 'std::string' containing the fail - reason, or an empty string otherwise. */ -extern std::string linux_ptrace_me_fail_reason (int err); +extern std::string linux_ptrace_attach_fail_reason (pid_t pid); + +/* Find all possible reasons we could have failed to attach to PTID + and return them as a string. ERR is the error PTRACE_ATTACH failed + with (an errno). */ +extern std::string linux_ptrace_attach_fail_reason_string (ptid_t ptid, int err); extern void linux_ptrace_init_warnings (void); extern void linux_check_ptrace_features (void); diff --git a/gdb/remote.c b/gdb/remote.c index efc5084cfe..21160e13ac 100644 --- a/gdb/remote.c +++ b/gdb/remote.c @@ -5825,20 +5825,8 @@ extended_remote_target::attach (const char *args, int from_tty) case PACKET_UNKNOWN: error (_("This target does not support attaching to a process")); default: - { - std::string errmsg = rs->buf.data (); - - if (!errmsg.empty ()) - { - /* Get rid of the "E." prefix. */ - errmsg.erase (0, 2); - } - - error (_("Attaching to %s failed%s%s"), - target_pid_to_str (ptid_t (pid)).c_str (), - !errmsg.empty () ? "\n" : "", - errmsg.c_str ()); - } + error (_("Attaching to %s failed"), + target_pid_to_str (ptid_t (pid)).c_str ()); } set_current_inferior (remote_add_inferior (false, pid, 1, 0)); -- 2.34.1