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[PATCH v12] exec: Fix dead-lock in de_thread with ptrace_attach

by Bernd Edlinger

This introduces signal->exec_bprm, which is used to fix the case when at least one of the sibling threads is traced, and therefore the trace process may dead-lock in ptrace_attach, but de_thread will need to wait for the tracer to continue execution. The solution is to detect this situation and allow ptrace_attach to continue by temporarily releasing the cred_guard_mutex, while de_thread() is still waiting for traced zombies to be eventually released by the tracer. In the case of the thread group leader we only have to wait for the thread to become a zombie, which may also need co-operation from the tracer due to PTRACE_O_TRACEEXIT. When a tracer wants to ptrace_attach a task that already is in execve, we simply retry the ptrace_may_access check while temporarily installing the new credentials and dumpability which are about to be used after execve completes. If the ptrace_attach happens on a thread that is a sibling-thread of the thread doing execve, it is sufficient to check against the old credentials, as this thread will be waited for, before the new credentials are installed. Other threads die quickly since the cred_guard_mutex is released, but a deadly signal is already pending. In case the mutex_lock_killable misses the signal, the non-zero current->signal->exec_bprm makes sure they release the mutex immediately and return with -ERESTARTNOINTR. This means there is no API change, unlike the previous version of this patch which was discussed here: https://lore.kernel.org/lkml/b6537ae6-31b1-5c50-f32b-8b8332ace882@hotmail.d… See tools/testing/selftests/ptrace/vmaccess.c for a test case that gets fixed by this change. Note that since the test case was originally designed to test the ptrace_attach returning an error in this situation, the test expectation needed to be adjusted, to allow the API to succeed at the first attempt. Signed-off-by: Bernd Edlinger <bernd.edlinger(a)hotmail.de> --- fs/exec.c | 69 ++++++++++++++++------- fs/proc/base.c | 6 ++ include/linux/cred.h | 1 + include/linux/sched/signal.h | 18 ++++++ kernel/cred.c | 28 +++++++-- kernel/ptrace.c | 32 +++++++++++ kernel/seccomp.c | 12 +++- tools/testing/selftests/ptrace/vmaccess.c | 23 +++++--- 8 files changed, 155 insertions(+), 34 deletions(-) v10: Changes to previous version, make the PTRACE_ATTACH retun -EAGAIN, instead of execve return -ERESTARTSYS. Added some lessions learned to the description. v11: Check old and new credentials in PTRACE_ATTACH again without changing the API. Note: I got actually one response from an automatic checker to the v11 patch, https://lore.kernel.org/lkml/202107121344.wu68hEPF-lkp@intel.com/ which is complaining about: >> kernel/ptrace.c:425:26: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected struct cred const *old_cred @@ got struct cred const [noderef] __rcu *real_cred @@ 417 struct linux_binprm *bprm = task->signal->exec_bprm; 418 const struct cred *old_cred; 419 struct mm_struct *old_mm; 420 421 retval = down_write_killable(&task->signal->exec_update_lock); 422 if (retval) 423 goto unlock_creds; 424 task_lock(task); > 425 old_cred = task->real_cred; v12: Essentially identical to v11. - Fixed a minor merge conflict in linux v5.17, and fixed the above mentioned nit by adding __rcu to the declaration. - re-tested the patch with all linux versions from v5.11 to v6.6 v10 was an alternative approach which did imply an API change. But I would prefer to avoid such an API change. The difficult part is getting the right dumpability flags assigned before de_thread starts, hope you like this version. If not, the v10 is of course also acceptable. Thanks Bernd. diff --git a/fs/exec.c b/fs/exec.c index 2f2b0acec4f0..902d3b230485 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1041,11 +1041,13 @@ static int exec_mmap(struct mm_struct *mm) return 0; } -static int de_thread(struct task_struct *tsk) +static int de_thread(struct task_struct *tsk, struct linux_binprm *bprm) { struct signal_struct *sig = tsk->signal; struct sighand_struct *oldsighand = tsk->sighand; spinlock_t *lock = &oldsighand->siglock; + struct task_struct *t = tsk; + bool unsafe_execve_in_progress = false; if (thread_group_empty(tsk)) goto no_thread_group; @@ -1068,6 +1070,19 @@ static int de_thread(struct task_struct *tsk) if (!thread_group_leader(tsk)) sig->notify_count--; + while_each_thread(tsk, t) { + if (unlikely(t->ptrace) + && (t != tsk->group_leader || !t->exit_state)) + unsafe_execve_in_progress = true; + } + + if (unlikely(unsafe_execve_in_progress)) { + spin_unlock_irq(lock); + sig->exec_bprm = bprm; + mutex_unlock(&sig->cred_guard_mutex); + spin_lock_irq(lock); + } + while (sig->notify_count) { __set_current_state(TASK_KILLABLE); spin_unlock_irq(lock); @@ -1158,6 +1173,11 @@ static int de_thread(struct task_struct *tsk) release_task(leader); } + if (unlikely(unsafe_execve_in_progress)) { + mutex_lock(&sig->cred_guard_mutex); + sig->exec_bprm = NULL; + } + sig->group_exec_task = NULL; sig->notify_count = 0; @@ -1169,6 +1189,11 @@ static int de_thread(struct task_struct *tsk) return 0; killed: + if (unlikely(unsafe_execve_in_progress)) { + mutex_lock(&sig->cred_guard_mutex); + sig->exec_bprm = NULL; + } + /* protects against exit_notify() and __exit_signal() */ read_lock(&tasklist_lock); sig->group_exec_task = NULL; @@ -1253,6 +1278,24 @@ int begin_new_exec(struct linux_binprm * bprm) if (retval) return retval; + /* If the binary is not readable then enforce mm->dumpable=0 */ + would_dump(bprm, bprm->file); + if (bprm->have_execfd) + would_dump(bprm, bprm->executable); + + /* + * Figure out dumpability. Note that this checking only of current + * is wrong, but userspace depends on it. This should be testing + * bprm->secureexec instead. + */ + if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP || + is_dumpability_changed(current_cred(), bprm->cred) || + !(uid_eq(current_euid(), current_uid()) && + gid_eq(current_egid(), current_gid()))) + set_dumpable(bprm->mm, suid_dumpable); + else + set_dumpable(bprm->mm, SUID_DUMP_USER); + /* * Ensure all future errors are fatal. */ @@ -1261,7 +1304,7 @@ int begin_new_exec(struct linux_binprm * bprm) /* * Make this the only thread in the thread group. */ - retval = de_thread(me); + retval = de_thread(me, bprm); if (retval) goto out; @@ -1284,11 +1327,6 @@ int begin_new_exec(struct linux_binprm * bprm) if (retval) goto out; - /* If the binary is not readable then enforce mm->dumpable=0 */ - would_dump(bprm, bprm->file); - if (bprm->have_execfd) - would_dump(bprm, bprm->executable); - /* * Release all of the old mmap stuff */ @@ -1350,18 +1388,6 @@ int begin_new_exec(struct linux_binprm * bprm) me->sas_ss_sp = me->sas_ss_size = 0; - /* - * Figure out dumpability. Note that this checking only of current - * is wrong, but userspace depends on it. This should be testing - * bprm->secureexec instead. - */ - if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP || - !(uid_eq(current_euid(), current_uid()) && - gid_eq(current_egid(), current_gid()))) - set_dumpable(current->mm, suid_dumpable); - else - set_dumpable(current->mm, SUID_DUMP_USER); - perf_event_exec(); __set_task_comm(me, kbasename(bprm->filename), true); @@ -1480,6 +1506,11 @@ static int prepare_bprm_creds(struct linux_binprm *bprm) if (mutex_lock_interruptible(&current->signal->cred_guard_mutex)) return -ERESTARTNOINTR; + if (unlikely(current->signal->exec_bprm)) { + mutex_unlock(&current->signal->cred_guard_mutex); + return -ERESTARTNOINTR; + } + bprm->cred = prepare_exec_creds(); if (likely(bprm->cred)) return 0; diff --git a/fs/proc/base.c b/fs/proc/base.c index ffd54617c354..0da9adfadb48 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2788,6 +2788,12 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf, if (rv < 0) goto out_free; + if (unlikely(current->signal->exec_bprm)) { + mutex_unlock(&current->signal->cred_guard_mutex); + rv = -ERESTARTNOINTR; + goto out_free; + } + rv = security_setprocattr(PROC_I(inode)->op.lsm, file->f_path.dentry->d_name.name, page, count); diff --git a/include/linux/cred.h b/include/linux/cred.h index f923528d5cc4..b01e309f5686 100644 --- a/include/linux/cred.h +++ b/include/linux/cred.h @@ -159,6 +159,7 @@ extern const struct cred *get_task_cred(struct task_struct *); extern struct cred *cred_alloc_blank(void); extern struct cred *prepare_creds(void); extern struct cred *prepare_exec_creds(void); +extern bool is_dumpability_changed(const struct cred *, const struct cred *); extern int commit_creds(struct cred *); extern void abort_creds(struct cred *); extern const struct cred *override_creds(const struct cred *); diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 0014d3adaf84..14df7073a0a8 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -234,9 +234,27 @@ struct signal_struct { struct mm_struct *oom_mm; /* recorded mm when the thread group got * killed by the oom killer */ + struct linux_binprm *exec_bprm; /* Used to check ptrace_may_access + * against new credentials while + * de_thread is waiting for other + * traced threads to terminate. + * Set while de_thread is executing. + * The cred_guard_mutex is released + * after de_thread() has called + * zap_other_threads(), therefore + * a fatal signal is guaranteed to be + * already pending in the unlikely + * event, that + * current->signal->exec_bprm happens + * to be non-zero after the + * cred_guard_mutex was acquired. + */ + struct mutex cred_guard_mutex; /* guard against foreign influences on * credential calculations * (notably. ptrace) + * Held while execve runs, except when + * a sibling thread is being traced. * Deprecated do not use in new code. * Use exec_update_lock instead. */ diff --git a/kernel/cred.c b/kernel/cred.c index 98cb4eca23fb..586cb6c7cf6b 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -433,6 +433,28 @@ static bool cred_cap_issubset(const struct cred *set, const struct cred *subset) return false; } +/** + * is_dumpability_changed - Will changing creds from old to new + * affect the dumpability in commit_creds? + * + * Return: false - dumpability will not be changed in commit_creds. + * Return: true - dumpability will be changed to non-dumpable. + * + * @old: The old credentials + * @new: The new credentials + */ +bool is_dumpability_changed(const struct cred *old, const struct cred *new) +{ + if (!uid_eq(old->euid, new->euid) || + !gid_eq(old->egid, new->egid) || + !uid_eq(old->fsuid, new->fsuid) || + !gid_eq(old->fsgid, new->fsgid) || + !cred_cap_issubset(old, new)) + return true; + + return false; +} + /** * commit_creds - Install new credentials upon the current task * @new: The credentials to be assigned @@ -467,11 +489,7 @@ int commit_creds(struct cred *new) get_cred(new); /* we will require a ref for the subj creds too */ /* dumpability changes */ - if (!uid_eq(old->euid, new->euid) || - !gid_eq(old->egid, new->egid) || - !uid_eq(old->fsuid, new->fsuid) || - !gid_eq(old->fsgid, new->fsgid) || - !cred_cap_issubset(old, new)) { + if (is_dumpability_changed(old, new)) { if (task->mm) set_dumpable(task->mm, suid_dumpable); task->pdeath_signal = 0; diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 443057bee87c..eb1c450bb7d7 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -20,6 +20,7 @@ #include <linux/pagemap.h> #include <linux/ptrace.h> #include <linux/security.h> +#include <linux/binfmts.h> #include <linux/signal.h> #include <linux/uio.h> #include <linux/audit.h> @@ -435,6 +436,28 @@ static int ptrace_attach(struct task_struct *task, long request, if (retval) goto unlock_creds; + if (unlikely(task->in_execve)) { + struct linux_binprm *bprm = task->signal->exec_bprm; + const struct cred __rcu *old_cred; + struct mm_struct *old_mm; + + retval = down_write_killable(&task->signal->exec_update_lock); + if (retval) + goto unlock_creds; + task_lock(task); + old_cred = task->real_cred; + old_mm = task->mm; + rcu_assign_pointer(task->real_cred, bprm->cred); + task->mm = bprm->mm; + retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS); + rcu_assign_pointer(task->real_cred, old_cred); + task->mm = old_mm; + task_unlock(task); + up_write(&task->signal->exec_update_lock); + if (retval) + goto unlock_creds; + } + write_lock_irq(&tasklist_lock); retval = -EPERM; if (unlikely(task->exit_state)) @@ -508,6 +531,14 @@ static int ptrace_traceme(void) { int ret = -EPERM; + if (mutex_lock_interruptible(&current->signal->cred_guard_mutex)) + return -ERESTARTNOINTR; + + if (unlikely(current->signal->exec_bprm)) { + mutex_unlock(&current->signal->cred_guard_mutex); + return -ERESTARTNOINTR; + } + write_lock_irq(&tasklist_lock); /* Are we already being traced? */ if (!current->ptrace) { @@ -523,6 +554,7 @@ static int ptrace_traceme(void) } } write_unlock_irq(&tasklist_lock); + mutex_unlock(&current->signal->cred_guard_mutex); return ret; } diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 255999ba9190..b29bbfa0b044 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -1955,9 +1955,15 @@ static long seccomp_set_mode_filter(unsigned int flags, * Make sure we cannot change seccomp or nnp state via TSYNC * while another thread is in the middle of calling exec. */ - if (flags & SECCOMP_FILTER_FLAG_TSYNC && - mutex_lock_killable(&current->signal->cred_guard_mutex)) - goto out_put_fd; + if (flags & SECCOMP_FILTER_FLAG_TSYNC) { + if (mutex_lock_killable(&current->signal->cred_guard_mutex)) + goto out_put_fd; + + if (unlikely(current->signal->exec_bprm)) { + mutex_unlock(&current->signal->cred_guard_mutex); + goto out_put_fd; + } + } spin_lock_irq(&current->sighand->siglock); diff --git a/tools/testing/selftests/ptrace/vmaccess.c b/tools/testing/selftests/ptrace/vmaccess.c index 4db327b44586..3b7d81fb99bb 100644 --- a/tools/testing/selftests/ptrace/vmaccess.c +++ b/tools/testing/selftests/ptrace/vmaccess.c @@ -39,8 +39,15 @@ TEST(vmaccess) f = open(mm, O_RDONLY); ASSERT_GE(f, 0); close(f); - f = kill(pid, SIGCONT); - ASSERT_EQ(f, 0); + f = waitpid(-1, NULL, 0); + ASSERT_NE(f, -1); + ASSERT_NE(f, 0); + ASSERT_NE(f, pid); + f = waitpid(-1, NULL, 0); + ASSERT_EQ(f, pid); + f = waitpid(-1, NULL, 0); + ASSERT_EQ(f, -1); + ASSERT_EQ(errno, ECHILD); } TEST(attach) @@ -57,22 +64,24 @@ TEST(attach) sleep(1); k = ptrace(PTRACE_ATTACH, pid, 0L, 0L); - ASSERT_EQ(errno, EAGAIN); - ASSERT_EQ(k, -1); + ASSERT_EQ(k, 0); k = waitpid(-1, &s, WNOHANG); ASSERT_NE(k, -1); ASSERT_NE(k, 0); ASSERT_NE(k, pid); ASSERT_EQ(WIFEXITED(s), 1); ASSERT_EQ(WEXITSTATUS(s), 0); - sleep(1); - k = ptrace(PTRACE_ATTACH, pid, 0L, 0L); + k = waitpid(-1, &s, 0); + ASSERT_EQ(k, pid); + ASSERT_EQ(WIFSTOPPED(s), 1); + ASSERT_EQ(WSTOPSIG(s), SIGTRAP); + k = ptrace(PTRACE_CONT, pid, 0L, 0L); ASSERT_EQ(k, 0); k = waitpid(-1, &s, 0); ASSERT_EQ(k, pid); ASSERT_EQ(WIFSTOPPED(s), 1); ASSERT_EQ(WSTOPSIG(s), SIGSTOP); - k = ptrace(PTRACE_DETACH, pid, 0L, 0L); + k = ptrace(PTRACE_CONT, pid, 0L, 0L); ASSERT_EQ(k, 0); k = waitpid(-1, &s, 0); ASSERT_EQ(k, pid); -- 2.39.2

42 minutes

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[PATCH bpf v3 0/2] bpf: fix bpf_d_path() helper prototype

by Shuran Liu

Hi, This series fixes a verifier issue with bpf_d_path() and adds a regression test to cover its use from an LSM program. Patch 1 updates the bpf_d_path() helper prototype so that the second argument is marked as MEM_WRITE. This makes it explicit to the verifier that the helper writes into the provided buffer. Patch 2 extends the existing d_path selftest to also cover the LSM bprm_check_security hook. The LSM program calls bpf_d_path() on the binary being executed and performs a simple prefix comparison on the resulting pathname. To avoid nondeterminism, the program filters based on an expected PID that is populated from userspace before the test binary is executed, and the parent and child processes are synchronized through a pipe so that the PID is set before exec. The test now uses bpf_for() to express the small fixed-iteration loop in a verifier-friendly way, and it removes the temporary /tmp/bpf_d_path_test binary in the cleanup path. Changelog ========= v3: - Switch the pathname prefix loop to use bpf_for() instead of #pragma unroll, as suggested by Matt. - Remove /tmp/bpf_d_path_test in the test cleanup path. - Add the missing Reviewed-by tags. v2: - Merge the new test into the existing d_path selftest rather than creating new files. - Add PID filtering in the LSM program to avoid nondeterministic failures due to unrelated processes triggering bprm_check_security. - Synchronize child execution using a pipe to ensure deterministic updates to the PID. Thanks for your time and reviews. Shuran Liu (2): bpf: mark bpf_d_path() buffer as writeable selftests/bpf: fix and consolidate d_path LSM regression test kernel/trace/bpf_trace.c | 2 +- .../testing/selftests/bpf/prog_tests/d_path.c | 65 +++++++++++++++++++ .../testing/selftests/bpf/progs/test_d_path.c | 33 ++++++++++ 3 files changed, 99 insertions(+), 1 deletion(-) -- 2.52.0

1 hour, 52 minutes

4
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[PATCH v1 0/4] bpf: Add wakeup_source iterators

by Samuel Wu

This patch series introduces BPF iterators for wakeup_source, enabling BPF programs to efficiently traverse a device's wakeup sources. Currently, inspecting wakeup sources typically involves reading interfaces like /sys/class/wakeup/* or debugfs. The repeated syscalls to query the sysfs nodes is inefficient, as there can be hundreds of wakeup_sources, and each wakeup source have multiple stats, with one sysfs node per stat. debugfs is unstable and insecure. This series implements two types of iterators: 1. Standard BPF Iterator: Allows creating a BPF link to iterate over wakeup sources 2. Open-coded Iterator: Enables the use of wakeup_source iterators directly within BPF programs Both iterators utilize pre-existing APIs wakeup_sources_walk_* to traverse over the SRCU that backs the list of wakeup_sources. Samuel Wu (4): bpf: Add wakeup_source iterator bpf: Open coded BPF for wakeup_sources selftests/bpf: Add tests for wakeup_sources selftests/bpf: Open coded BPF wakeup_sources test kernel/bpf/Makefile | 1 + kernel/bpf/helpers.c | 3 + kernel/bpf/wakeup_source_iter.c | 137 ++++++++ .../testing/selftests/bpf/bpf_experimental.h | 5 + tools/testing/selftests/bpf/config | 1 + .../bpf/prog_tests/wakeup_source_iter.c | 323 ++++++++++++++++++ .../selftests/bpf/progs/wakeup_source_iter.c | 117 +++++++ 7 files changed, 587 insertions(+) create mode 100644 kernel/bpf/wakeup_source_iter.c create mode 100644 tools/testing/selftests/bpf/prog_tests/wakeup_source_iter.c create mode 100644 tools/testing/selftests/bpf/progs/wakeup_source_iter.c -- 2.52.0.177.g9f829587af-goog

3 hours, 41 minutes

1
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[PATCH] selftests: gpio: correctly check the type of /dev/gpiochipX

by Guixin Liu

/dev/gpiochipX is a character device, not a directory, so we should use "test -c" instead of "test -d" to check for its existence; otherwise, the current check will not work correctly when /dev/gpiochipX is left over (e.g., as a stale device node). Signed-off-by: Guixin Liu <kanie(a)linux.alibaba.com> --- tools/testing/selftests/gpio/gpio-aggregator.sh | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/gpio/gpio-aggregator.sh b/tools/testing/selftests/gpio/gpio-aggregator.sh index 9b6f80ad9f8a..13d8e1607571 100755 --- a/tools/testing/selftests/gpio/gpio-aggregator.sh +++ b/tools/testing/selftests/gpio/gpio-aggregator.sh @@ -351,7 +351,7 @@ test "$(agg_get_chip_num_lines _sysfs.0)" = "1" || fail "number of lines is not test "$(agg_get_line_name _sysfs.0 0)" = "" || fail "line name is unset" echo "$(agg_configfs_dev_name _sysfs.0)" > "$SYSFS_AGG_DIR/delete_device" test -d $CONFIGFS_AGG_DIR/_sysfs.0 && fail "_sysfs.0 unexpectedly remains" -test -d /dev/${CHIPNAME} && fail "/dev/${CHIPNAME} unexpectedly remains" +test -c /dev/${CHIPNAME} && fail "/dev/${CHIPNAME} unexpectedly remains" echo "1.2.2. Complex creation/deletion" echo "chip0bank0_0 chip1_bank1 10-11" > "$SYSFS_AGG_DIR/new_device" @@ -365,7 +365,7 @@ test "$(agg_get_line_name _sysfs.0 1)" = "" || fail "line name is unset" test "$(agg_get_line_name _sysfs.0 2)" = "" || fail "line name is unset" echo "$(agg_configfs_dev_name _sysfs.0)" > "$SYSFS_AGG_DIR/delete_device" test -d $CONFIGFS_AGG_DIR/_sysfs.0 && fail "_sysfs.0 unexpectedly remains" -test -d /dev/${CHIPNAME} && fail "/dev/${CHIPNAME} unexpectedly remains" +test -c /dev/${CHIPNAME} && fail "/dev/${CHIPNAME} unexpectedly remains" echo "1.2.3. Asynchronous creation with deferred probe" sim_disable_chip chip0 @@ -382,7 +382,7 @@ test "$(agg_get_chip_num_lines _sysfs.0)" = "1" || fail "number of lines is not test "$(agg_get_line_name _sysfs.0 0)" = "" || fail "line name unexpectedly set" echo "$(agg_configfs_dev_name _sysfs.0)" > "$SYSFS_AGG_DIR/delete_device" test -d $CONFIGFS_AGG_DIR/_sysfs.0 && fail "_sysfs.0 unexpectedly remains" -test -d /dev/${CHIPNAME} && fail "/dev/${CHIPNAME} unexpectedly remains" +test -c /dev/${CHIPNAME} && fail "/dev/${CHIPNAME} unexpectedly remains" echo "1.2.4. Can't instantiate a chip with invalid configuration" echo "xyz 0" > "$SYSFS_AGG_DIR/new_device" -- 2.43.0

4 hours, 45 minutes

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[PATCH bpf 1/2] bpf: Fix truncated dmabuf iterator reads

by T.J. Mercier

If there is a large number (hundreds) of dmabufs allocated, the text output generated from dmabuf_iter_seq_show can exceed common user buffer sizes (e.g. PAGE_SIZE) necessitating multiple start/stop cycles to iterate through all dmabufs. However the dmabuf iterator currently returns NULL in dmabuf_iter_seq_start for all non-zero pos values, which results in the truncation of the output before all dmabufs are handled. After dma_buf_iter_begin / dma_buf_iter_next, the refcount of the buffer is elevated so that the BPF iterator program can run without holding any locks. When a stop occurs, instead of immediately dropping the reference on the buffer, stash a pointer to the buffer in seq->priv until either start is called or the iterator is released. This also enables the resumption of iteration without first walking through the list of dmabufs based on the pos value. Fixes: 76ea95534995 ("bpf: Add dmabuf iterator") Signed-off-by: T.J. Mercier <tjmercier(a)google.com> --- kernel/bpf/dmabuf_iter.c | 56 +++++++++++++++++++++++++++++++++++----- 1 file changed, 49 insertions(+), 7 deletions(-) diff --git a/kernel/bpf/dmabuf_iter.c b/kernel/bpf/dmabuf_iter.c index 4dd7ef7c145c..cd500248abd9 100644 --- a/kernel/bpf/dmabuf_iter.c +++ b/kernel/bpf/dmabuf_iter.c @@ -6,10 +6,33 @@ #include <linux/kernel.h> #include <linux/seq_file.h> +struct dmabuf_iter_priv { + /* + * If this pointer is non-NULL, the buffer's refcount is elevated to + * prevent destruction between stop/start. If reading is not resumed and + * start is never called again, then dmabuf_iter_seq_fini drops the + * reference when the iterator is released. + */ + struct dma_buf *dmabuf; +}; + static void *dmabuf_iter_seq_start(struct seq_file *seq, loff_t *pos) { - if (*pos) - return NULL; + struct dmabuf_iter_priv *p = seq->private; + + if (*pos) { + struct dma_buf *dmabuf = p->dmabuf; + + if (!dmabuf) + return NULL; + + /* + * Always resume from where we stopped, regardless of the value + * of pos. + */ + p->dmabuf = NULL; + return dmabuf; + } return dma_buf_iter_begin(); } @@ -54,8 +77,11 @@ static void dmabuf_iter_seq_stop(struct seq_file *seq, void *v) { struct dma_buf *dmabuf = v; - if (dmabuf) - dma_buf_put(dmabuf); + if (dmabuf) { + struct dmabuf_iter_priv *p = seq->private; + + p->dmabuf = dmabuf; + } } static const struct seq_operations dmabuf_iter_seq_ops = { @@ -71,11 +97,27 @@ static void bpf_iter_dmabuf_show_fdinfo(const struct bpf_iter_aux_info *aux, seq_puts(seq, "dmabuf iter\n"); } +static int dmabuf_iter_seq_init(void *priv, struct bpf_iter_aux_info *aux) +{ + struct dmabuf_iter_priv *p = (struct dmabuf_iter_priv *)priv; + + p->dmabuf = NULL; + return 0; +} + +static void dmabuf_iter_seq_fini(void *priv) +{ + struct dmabuf_iter_priv *p = (struct dmabuf_iter_priv *)priv; + + if (p->dmabuf) + dma_buf_put(p->dmabuf); +} + static const struct bpf_iter_seq_info dmabuf_iter_seq_info = { .seq_ops = &dmabuf_iter_seq_ops, - .init_seq_private = NULL, - .fini_seq_private = NULL, - .seq_priv_size = 0, + .init_seq_private = dmabuf_iter_seq_init, + .fini_seq_private = dmabuf_iter_seq_fini, + .seq_priv_size = sizeof(struct dmabuf_iter_priv), }; static struct bpf_iter_reg bpf_dmabuf_reg_info = { base-commit: 30f09200cc4aefbd8385b01e41bde2e4565a6f0e -- 2.52.0.177.g9f829587af-goog

6 hours, 28 minutes

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[GIT PULL] kunit next update for Linux 6.19-rc1

by Shuah Khan

Hi Linus, Please pull the following kunit next update for Linux 6.19-rc1. Makes filter parameters configurable via Kconfig. Adds description of kunit.enable parameter documentation. diff is attached. thanks, -- Shuah ---------------------------------------------------------------- The following changes since commit 3a8660878839faadb4f1a6dd72c3179c1df56787: Linux 6.18-rc1 (2025-10-12 13:42:36 -0700) are available in the Git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest tags/linux_kselftest-kunit-6.19-rc1 for you to fetch changes up to 7bc16e72ddb993d706f698c2f6cee694e485f557: kunit: Make filter parameters configurable via Kconfig (2025-11-14 11:02:34 -0700) ---------------------------------------------------------------- linux_kselftest-kunit-6.19-rc1 Makes filter parameters configurable via Kconfig. Adds description of kunit.enable parameter documentation. ---------------------------------------------------------------- Thomas Weißschuh (1): kunit: Make filter parameters configurable via Kconfig Yuya Ishikawa (1): Documentation: kunit: add description of kunit.enable parameter Documentation/dev-tools/kunit/run_manual.rst | 6 ++++++ lib/kunit/Kconfig | 24 ++++++++++++++++++++++++ lib/kunit/executor.c | 8 +++++--- 3 files changed, 35 insertions(+), 3 deletions(-) ----------------------------------------------------------------

6 hours, 41 minutes

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[GIT PULL] kselftest next update for Linux 6.19-rc1

by Shuah Khan

Hi Linus, Please pull this kselftest next update for Linux 6.19-rc1 Adds basic test for trace_marker_raw file to tracing selftest. Fixes invalid array access in printf dma_map_benchmark selftest. Adds tprobe enable/disable testcase to tracing selftest. Updates fprobe selftest for ftrace based fprobe. diff is attached. thanks, -- Shuah ---------------------------------------------------------------- The following changes since commit 3a8660878839faadb4f1a6dd72c3179c1df56787: Linux 6.18-rc1 (2025-10-12 13:42:36 -0700) are available in the Git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest tags/linux_kselftest-next-6.19-rc1 for you to fetch changes up to a2f7990d330937a204b86b9cafbfef82f87a8693: selftests: tracing: Update fprobe selftest for ftrace based fprobe (2025-11-19 15:55:14 -0700) ---------------------------------------------------------------- linux_kselftest-next-6.19-rc1 Adds basic test for trace_marker_raw file to tracing selftest. Fixes invalid array access in printf dma_map_benchmark selftest. Adds tprobe enable/disable testcase to tracing selftest. Updates fprobe selftest for ftrace based fprobe. ---------------------------------------------------------------- Brendan Jackman (1): selftests/run_kselftest.sh: exit with error if tests fail Masami Hiramatsu (Google) (2): selftests: tracing: Add tprobe enable/disable testcase selftests: tracing: Update fprobe selftest for ftrace based fprobe Steven Rostedt (1): selftests/tracing: Add basic test for trace_marker_raw file Zhang Chujun (1): selftests/dma: fix invalid array access in printf tools/testing/selftests/dma/dma_map_benchmark.c | 2 +- .../ftrace/test.d/00basic/trace_marker_raw.tc | 107 +++++++++++++++++++++ .../ftrace/test.d/dynevent/add_remove_fprobe.tc | 18 +--- .../test.d/dynevent/enable_disable_tprobe.tc | 40 ++++++++ tools/testing/selftests/kselftest/runner.sh | 14 ++- tools/testing/selftests/run_kselftest.sh | 14 +++ 6 files changed, 176 insertions(+), 19 deletions(-) create mode 100644 tools/testing/selftests/ftrace/test.d/00basic/trace_marker_raw.tc create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/enable_disable_tprobe.tc ----------------------------------------------------------------

6 hours, 41 minutes

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Problems when trying to build tools/testing/selftests

by Guenter Roeck

Hi, when trying to build tools/testing/selftests, I get a lot of warnings such as mount-notify_test.c: In function ‘fanotify_fsmount’: mount-notify_test.c:360:14: warning: implicit declaration of function ‘fsopen’; did you mean ‘fdopen’? and subsequent build errors. testing/selftests/filesystems/mount-notify/mount-notify_test.c:360: undefined reference to `fsopen' /usr/bin/ld: tools/testing/selftests/filesystems/mount-notify/mount-notify_test.c:363: undefined reference to `fsconfig' /usr/bin/ld:tools/testing/selftests/filesystems/mount-notify/mount-notify_test.c:366: undefined reference to `fsmount' /usr/bin/ld: tools/testing/selftests/filesystems/mount-notify/mount-notify_test.c:371: undefined reference to `move_mount' This does not just affect a single file, but several of them. What am I missing ? Is there some magic needed to build the selftests ? Thanks, Guenter

8 hours, 6 minutes

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[PATCH v2 00/13] tools/nolibc: always use 64-bit time-related types

by Thomas Weißschuh

nolibc currently uses 32-bit types for various APIs. These are problematic as their reduced value range can lead to truncated values. Intended for 6.19. Signed-off-by: Thomas Weißschuh <linux(a)weissschuh.net> --- Changes in v2: - Drop already applied ino_t and off_t patches. - Also handle 'struct timeval'. - Make the progression of the series a bit clearer. - Add compatibility assertions. - Link to v1: https://lore.kernel.org/r/20251029-nolibc-uapi-types-v1-0-e79de3b215d8@weis… --- Thomas Weißschuh (13): tools/nolibc/poll: use kernel types for system call invocations tools/nolibc/poll: drop __NR_poll fallback tools/nolibc/select: drop non-pselect based implementations tools/nolibc/time: drop invocation of gettimeofday system call tools/nolibc: prefer explicit 64-bit time-related system calls tools/nolibc/gettimeofday: avoid libgcc 64-bit divisions tools/nolibc/select: avoid libgcc 64-bit multiplications tools/nolibc: use custom structs timespec and timeval tools/nolibc: always use 64-bit time types selftests/nolibc: test compatibility of nolibc and kernel time types tools/nolibc: remove time conversions tools/nolibc: add __nolibc_static_assert() selftests/nolibc: add static assertions around time types handling tools/include/nolibc/arch-s390.h | 3 + tools/include/nolibc/compiler.h | 2 + tools/include/nolibc/poll.h | 14 ++-- tools/include/nolibc/std.h | 2 +- tools/include/nolibc/sys/select.h | 25 ++----- tools/include/nolibc/sys/time.h | 6 +- tools/include/nolibc/sys/timerfd.h | 32 +++------ tools/include/nolibc/time.h | 102 +++++++++------------------ tools/include/nolibc/types.h | 17 ++++- tools/testing/selftests/nolibc/nolibc-test.c | 27 +++++++ 10 files changed, 107 insertions(+), 123 deletions(-) --- base-commit: 586e8d5137dfcddfccca44c3b992b92d2be79347 change-id: 20251001-nolibc-uapi-types-1c072d10fcc7 Best regards, -- Thomas Weißschuh <linux(a)weissschuh.net>

10 hours, 23 minutes

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[PATCH 00/21] vfio/pci: Base support to preserve a VFIO device file across Live Update

by David Matlack

This series adds the base support to preserve a VFIO device file across a Live Update. "Base support" means that this allows userspace to safetly preserve a VFIO device file with LIVEUPDATE_SESSION_PRESERVE_FD and retrieve a preserved VFIO device file with LIVEUPDATE_SESSION_RETRIEVE_FD, but the device itself is not preserved in a fully running state across Live Update. This series unblocks 2 parallel but related streams of work: - iommufd preservation across Live Update. This work spans iommufd, the IOMMU subsystem, and IOMMU drivers [1] - Preservation of VFIO device state across Live Update (config space, BAR addresses, power state, SR-IOV state, etc.). This work spans both VFIO and the core PCI subsystem. While we need all of the above to fully preserve a VFIO device across a Live Update without disrupting the workload on the device, this series aims to be functional and safe enough to merge as the first incremental step toward that goal. Areas for Discussion -------------------- BDF Stability across Live Update The PCI support for tracking preserved devices across a Live Update to prevent auto-probing relies on PCI segment numbers and BDFs remaining stable. For now I have disallowed VFs, as the BDFs assigned to VFs can vary depending on how the kernel chooses to allocate bus numbers. For non-VFs I am wondering if there is any more needed to ensure BDF stability across Live Update. While we would like to support many different systems and configurations in due time (including preserving VFs), I'd like to keep this first serses constrained to simple use-cases. FLB Locking I don't see a way to properly synchronize pci_flb_finish() with pci_liveupdate_incoming_is_preserved() since the incoming FLB mutex is dropped by liveupdate_flb_get_incoming() when it returns the pointer to the object, and taking pci_flb_incoming_lock in pci_flb_finish() could result in a deadlock due to reversing the lock ordering. FLB Retrieving The first patch of this series includes a fix to prevent an FLB from being retrieved again it is finished. I am wondering if this is the right approach or if subsystems are expected to stop calling liveupdate_flb_get_incoming() after an FLB is finished. Testing ------- The patches at the end of this series provide comprehensive selftests for the new code added by this series. The selftests have been validated in both a VM environment using a virtio-net PCIe device, and in a baremetal environment on an Intel EMR server with an Intel DSA device. Here is an example of how to run the new selftests: vfio_pci_liveupdate_uapi_test: $ tools/testing/selftests/vfio/scripts/setup.sh 0000:00:04.0 $ tools/testing/selftests/vfio/vfio_pci_liveupdate_uapi_test 0000:00:04.0 $ tools/testing/selftests/vfio/scripts/cleanup.sh vfio_pci_liveupdate_kexec_test: $ tools/testing/selftests/vfio/scripts/setup.sh 0000:00:04.0 $ tools/testing/selftests/vfio/vfio_pci_liveupdate_kexec_test --stage 1 0000:00:04.0 $ kexec [...] # NOTE: distro-dependent $ tools/testing/selftests/vfio/scripts/setup.sh 0000:00:04.0 $ tools/testing/selftests/vfio/vfio_pci_liveupdate_kexec_test --stage 2 0000:00:04.0 $ tools/testing/selftests/vfio/scripts/cleanup.sh Dependencies ------------ This series was constructed on top of several in-flight series and on top of mm-nonmm-unstable [2]. +-- This series | +-- [PATCH v2 00/18] vfio: selftests: Support for multi-device tests | https://lore.kernel.org/kvm/20251112192232.442761-1-dmatlack@google.com/ | +-- [PATCH v3 0/4] vfio: selftests: update DMA mapping tests to use queried IOVA ranges | https://lore.kernel.org/kvm/20251111-iova-ranges-v3-0-7960244642c5@fb.com/ | +-- [PATCH v8 0/2] Live Update: File-Lifecycle-Bound (FLB) State | https://lore.kernel.org/linux-mm/20251125225006.3722394-1-pasha.tatashin@so… | +-- [PATCH v8 00/18] Live Update Orchestrator | https://lore.kernel.org/linux-mm/20251125165850.3389713-1-pasha.tatashin@so… | To simplify checking out the code, this series can be found on GitHub: https://github.com/dmatlack/linux/tree/liveupdate/vfio/cdev/v1 Changelog --------- v1: - Rebase series on top of LUOv8 and VFIO selftests improvements - Drop commits to preserve config space fields across Live Update. These changes require changes to the PCI layer. For exmaple, preserving rbars could lead to an inconsistent device state until device BARs addresses are preserved across Live Update. - Drop commits to preserve Bus Master Enable on the device. There's no reason to preserve this until iommufd preservation is fully working. Furthermore, preserving Bus Master Enable could lead to memory corruption when the device if the device is bound to the default identity-map domain after Live Update. - Drop commits to preserve saved PCI state. This work is not needed until we are ready to preserve the device's config space, and requires more thought to make the PCI state data layout ABI-friendly. - Add support to skip auto-probing devices that are preserved by VFIO to avoid them getting bound to a different driver by the next kernel. - Restrict device preservation further (no VFs, no intel-graphics). - Various refactoring and small edits to improve readability and eliminate code duplication. rfc: https://lore.kernel.org/kvm/20251018000713.677779-1-vipinsh@google.com/ Cc: Saeed Mahameed <saeedm(a)nvidia.com> Cc: Adithya Jayachandran <ajayachandra(a)nvidia.com> Cc: Jason Gunthorpe <jgg(a)nvidia.com> Cc: Parav Pandit <parav(a)nvidia.com> Cc: Leon Romanovsky <leonro(a)nvidia.com> Cc: William Tu <witu(a)nvidia.com> Cc: Jacob Pan <jacob.pan(a)linux.microsoft.com> Cc: Lukas Wunner <lukas(a)wunner.de> Cc: Pasha Tatashin <pasha.tatashin(a)soleen.com> Cc: Mike Rapoport <rppt(a)kernel.org> Cc: Pratyush Yadav <pratyush(a)kernel.org> Cc: Samiullah Khawaja <skhawaja(a)google.com> Cc: Chris Li <chrisl(a)kernel.org> Cc: Josh Hilke <jrhilke(a)google.com> Cc: David Rientjes <rientjes(a)google.com> [1] https://lore.kernel.org/linux-iommu/20250928190624.3735830-1-skhawaja@googl… [2] https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git/log/?h=mm-nonmm… David Matlack (12): liveupdate: luo_flb: Prevent retrieve() after finish() PCI: Add API to track PCI devices preserved across Live Update PCI: Require driver_override for incoming Live Update preserved devices vfio/pci: Notify PCI subsystem about devices preserved across Live Update vfio: Enforce preserved devices are retrieved via LIVEUPDATE_SESSION_RETRIEVE_FD vfio/pci: Store Live Update state in struct vfio_pci_core_device vfio: selftests: Add Makefile support for TEST_GEN_PROGS_EXTENDED vfio: selftests: Add vfio_pci_liveupdate_uapi_test vfio: selftests: Expose iommu_modes to tests vfio: selftests: Expose low-level helper routines for setting up struct vfio_pci_device vfio: selftests: Verify that opening VFIO device fails during Live Update vfio: selftests: Add continuous DMA to vfio_pci_liveupdate_kexec_test Vipin Sharma (9): vfio/pci: Register a file handler with Live Update Orchestrator vfio/pci: Preserve vfio-pci device files across Live Update vfio/pci: Retrieve preserved device files after Live Update vfio/pci: Skip reset of preserved device after Live Update selftests/liveupdate: Move luo_test_utils.* into a reusable library selftests/liveupdate: Add helpers to preserve/retrieve FDs vfio: selftests: Build liveupdate library in VFIO selftests vfio: selftests: Initialize vfio_pci_device using a VFIO cdev FD vfio: selftests: Add vfio_pci_liveupdate_kexec_test MAINTAINERS | 1 + drivers/pci/Makefile | 1 + drivers/pci/liveupdate.c | 248 ++++++++++++++++ drivers/pci/pci-driver.c | 12 +- drivers/vfio/device_cdev.c | 25 +- drivers/vfio/group.c | 9 + drivers/vfio/pci/Makefile | 1 + drivers/vfio/pci/vfio_pci.c | 11 +- drivers/vfio/pci/vfio_pci_core.c | 23 +- drivers/vfio/pci/vfio_pci_liveupdate.c | 278 ++++++++++++++++++ drivers/vfio/pci/vfio_pci_priv.h | 16 + drivers/vfio/vfio.h | 13 - drivers/vfio/vfio_main.c | 22 +- include/linux/kho/abi/pci.h | 53 ++++ include/linux/kho/abi/vfio_pci.h | 45 +++ include/linux/liveupdate.h | 3 + include/linux/pci.h | 38 +++ include/linux/vfio.h | 51 ++++ include/linux/vfio_pci_core.h | 7 + kernel/liveupdate/luo_flb.c | 4 + tools/testing/selftests/liveupdate/.gitignore | 1 + tools/testing/selftests/liveupdate/Makefile | 14 +- .../include/libliveupdate.h} | 11 +- .../selftests/liveupdate/lib/libliveupdate.mk | 20 ++ .../{luo_test_utils.c => lib/liveupdate.c} | 43 ++- .../selftests/liveupdate/luo_kexec_simple.c | 2 +- .../selftests/liveupdate/luo_multi_session.c | 2 +- tools/testing/selftests/vfio/Makefile | 23 +- .../vfio/lib/include/libvfio/iommu.h | 2 + .../lib/include/libvfio/vfio_pci_device.h | 8 + tools/testing/selftests/vfio/lib/iommu.c | 4 +- .../selftests/vfio/lib/vfio_pci_device.c | 60 +++- .../vfio/vfio_pci_liveupdate_kexec_test.c | 255 ++++++++++++++++ .../vfio/vfio_pci_liveupdate_uapi_test.c | 93 ++++++ 34 files changed, 1313 insertions(+), 86 deletions(-) create mode 100644 drivers/pci/liveupdate.c create mode 100644 drivers/vfio/pci/vfio_pci_liveupdate.c create mode 100644 include/linux/kho/abi/pci.h create mode 100644 include/linux/kho/abi/vfio_pci.h rename tools/testing/selftests/liveupdate/{luo_test_utils.h => lib/include/libliveupdate.h} (80%) create mode 100644 tools/testing/selftests/liveupdate/lib/libliveupdate.mk rename tools/testing/selftests/liveupdate/{luo_test_utils.c => lib/liveupdate.c} (89%) create mode 100644 tools/testing/selftests/vfio/vfio_pci_liveupdate_kexec_test.c create mode 100644 tools/testing/selftests/vfio/vfio_pci_liveupdate_uapi_test.c -- 2.52.0.487.g5c8c507ade-goog

13 hours, 2 minutes

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