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| author | Eric W. Biederman <ebiederm@xmission.com> | 2017-05-22 23:40:12 +0300 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2017-05-23 15:40:44 +0300 |
| commit | c70d9d809fdeecedb96972457ee45c49a232d97f (patch) | |
| tree | d814992a6f46fdc1b9faac491aaa30744cb2ed57 /include | |
| parent | 3fd37226216620c1a468afa999739d5016fbc349 (diff) | |
| download | linux-c70d9d809fdeecedb96972457ee45c49a232d97f.tar.xz | |
ptrace: Properly initialize ptracer_cred on fork
When I introduced ptracer_cred I failed to consider the weirdness of
fork where the task_struct copies the old value by default. This
winds up leaving ptracer_cred set even when a process forks and
the child process does not wind up being ptraced.
Because ptracer_cred is not set on non-ptraced processes whose
parents were ptraced this has broken the ability of the enlightenment
window manager to start setuid children.
Fix this by properly initializing ptracer_cred in ptrace_init_task
This must be done with a little bit of care to preserve the current value
of ptracer_cred when ptrace carries through fork. Re-reading the
ptracer_cred from the ptracing process at this point is inconsistent
with how PT_PTRACE_CAP has been maintained all of these years.
Tested-by: Takashi Iwai <tiwai@suse.de>
Fixes: 64b875f7ac8a ("ptrace: Capture the ptracer's creds not PT_PTRACE_CAP")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/ptrace.h | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h index 422bc2e4cb6a..ef3eb8bbfee4 100644 --- a/include/linux/ptrace.h +++ b/include/linux/ptrace.h @@ -54,7 +54,8 @@ extern int ptrace_request(struct task_struct *child, long request, unsigned long addr, unsigned long data); extern void ptrace_notify(int exit_code); extern void __ptrace_link(struct task_struct *child, - struct task_struct *new_parent); + struct task_struct *new_parent, + const struct cred *ptracer_cred); extern void __ptrace_unlink(struct task_struct *child); extern void exit_ptrace(struct task_struct *tracer, struct list_head *dead); #define PTRACE_MODE_READ 0x01 @@ -206,7 +207,7 @@ static inline void ptrace_init_task(struct task_struct *child, bool ptrace) if (unlikely(ptrace) && current->ptrace) { child->ptrace = current->ptrace; - __ptrace_link(child, current->parent); + __ptrace_link(child, current->parent, current->ptracer_cred); if (child->ptrace & PT_SEIZED) task_set_jobctl_pending(child, JOBCTL_TRAP_STOP); @@ -215,6 +216,8 @@ static inline void ptrace_init_task(struct task_struct *child, bool ptrace) set_tsk_thread_flag(child, TIF_SIGPENDING); } + else + child->ptracer_cred = NULL; } /** |