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Kernel+LibC: Introduce a "dumpable" flag for processes

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This new flag controls two things:
- Whether the kernel will generate core dumps for the process
- Whether the EUID:EGID should own the process's files in /proc

Processes are automatically made non-dumpable when their EUID or EGID is
changed, either via syscalls that specifically modify those ID's, or via
sys$execve(), when a set-uid or set-gid program is executed.

A process can change its own dumpable flag at any time by calling the
new sys$prctl(PR_SET_DUMPABLE) syscall.

Fixes #4504.
This commit is contained in:
Andreas Kling 2020-12-25 18:27:42 +01:00
parent 3c9bd911b8
commit 82f86e35d6
13 changed files with 199 additions and 7 deletions
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17
Kernel/Syscalls/setuid.cpp
View file

@ -35,6 +35,8 @@ int Process::sys$seteuid(uid_t euid)
if (euid != m_uid && euid != m_suid && !is_superuser())
return -EPERM;
if (m_euid != euid)
set_dumpable(false);
m_euid = euid;
return 0;
}
@ -46,6 +48,9 @@ int Process::sys$setegid(gid_t egid)
if (egid != m_gid && egid != m_sgid && !is_superuser())
return -EPERM;
if (m_egid != egid)
set_dumpable(false);
m_egid = egid;
return 0;
}
@ -57,6 +62,9 @@ int Process::sys$setuid(uid_t uid)
if (uid != m_uid && uid != m_euid && !is_superuser())
return -EPERM;
if (m_euid != uid)
set_dumpable(false);
m_uid = uid;
m_euid = uid;
m_suid = uid;
@ -70,6 +78,9 @@ int Process::sys$setgid(gid_t gid)
if (gid != m_gid && gid != m_egid && !is_superuser())
return -EPERM;
if (m_egid != gid)
set_dumpable(false);
m_gid = gid;
m_egid = gid;
m_sgid = gid;
@ -91,6 +102,9 @@ int Process::sys$setresuid(uid_t ruid, uid_t euid, uid_t suid)
if ((!ok(ruid) || !ok(euid) || !ok(suid)) && !is_superuser())
return -EPERM;
if (m_euid != euid)
set_dumpable(false);
m_uid = ruid;
m_euid = euid;
m_suid = suid;
@ -112,6 +126,9 @@ int Process::sys$setresgid(gid_t rgid, gid_t egid, gid_t sgid)
if ((!ok(rgid) || !ok(egid) || !ok(sgid)) && !is_superuser())
return -EPERM;
if (m_egid != egid)
set_dumpable(false);
m_gid = rgid;
m_egid = egid;
m_sgid = sgid;