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From: "vries at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>
To: gdb-prs@sourceware.org
Subject: [Bug external/31520] [gdb/external] Handle kernel.yama.ptrace_scope
 != 0
Date: Thu, 21 Mar 2024 13:28:43 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D31520

--- Comment #1 from Tom de Vries <vries at gcc dot gnu.org> ---
So, this is the problem:
...
$ sleep 60 & gdb -q -p $(pidof sleep)
[4] 1786
Attaching to process 1786
ptrace: Operation not permitted.
(gdb)=20
...

And this is the solution using sudo:
...
$ sleep 60 & sudo gdb -q -p $(pidof sleep)
[1] 1986
Attaching to process 1986
Reading symbols from /usr/bin/sleep...
(No debugging symbols found in /usr/bin/sleep)
Reading symbols from /lib64/libc.so.6...
(No debugging symbols found in /lib64/libc.so.6)
Reading symbols from /lib64/ld-linux-x86-64.so.2...
(No debugging symbols found in /lib64/ld-linux-x86-64.so.2)
0x00007f2fd01d70ca in clock_nanosleep@GLIBC_2.2.5 () from /lib64/libc.so.6
Missing separate debuginfos, use: zypper install
coreutils-debuginfo-8.32-150400.7.5.x86_64
(gdb) shell whoami
root
(gdb)=20
...

And this is a solution using ptrace capabilities:
...
# sleep 60 & ./sudo-allow-ptrace.sh gdb -q -p $(pidof sleep)
[1] 1925
+ sudo -E capsh '--caps=3Dcap_setpcap,cap_setuid,cap_setgid+ep
cap_sys_ptrace+eip' --keep=3D1 --user=3Dvries --addamb=3Dcap_sys_ptrace --s=
hell=3Dgdb
-- -q -p 1925
Attaching to process 1925
Reading symbols from /usr/bin/sleep...
(No debugging symbols found in /usr/bin/sleep)
Reading symbols from /lib64/libc.so.6...
(No debugging symbols found in /lib64/libc.so.6)
Reading symbols from /lib64/ld-linux-x86-64.so.2...
(No debugging symbols found in /lib64/ld-linux-x86-64.so.2)
0x00007feb59fed0ca in clock_nanosleep@GLIBC_2.2.5 () from /lib64/libc.so.6
(gdb) shell whoami
vries
(gdb)=20
...
where ./sudo-allow-ptrace.sh is:
...
#!/bin/sh

shell=3D"$1"
shift

set -x

sudo \
    -E capsh \
    --caps=3D"cap_setpcap,cap_setuid,cap_setgid+ep cap_sys_ptrace+eip" \
    --keep=3D1 \
    --user=3D"$USER" \
    --addamb=3D"cap_sys_ptrace" \
    --shell=3D$shell -- \
    "$@"
...

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