2022-04-22 19:06:43

by Aaron Tomlin

Subject: [PATCH v3 0/2] module: Introduce module unload taint tracking

Hi Luis,

This is based on the latest mcgrof/modules-next branch. I have decided
still to use RCU even though no entry is ever removed from the unloaded
tainted modules list. That being said, if I understand correctly, it is not
safe in some instances to use 'module_mutex' in print_modules(). So instead
we disable preemption to ensure list traversal with concurrent list
manipulation e.g. list_add_rcu(), is safe too.

Changes since RFC v2 [1]
- Dropped RFC from subject
- Removed the newline i.e. "\n" in printk()
- Always include the tainted module's unload count
- Unconditionally display each unloaded tainted module

Please let me know your thoughts.

[1]: https://lore.kernel.org/all/[email protected]/


Aaron Tomlin (2):
module: Make module_flags_taint() accept a module's taints bitmap
directly
module: Introduce module unload taint tracking

init/Kconfig | 11 +++++++
kernel/module/main.c | 73 +++++++++++++++++++++++++++++++++++++++++---
2 files changed, 80 insertions(+), 4 deletions(-)


base-commit: eeaec7801c421e17edda6e45a32d4a5596b633da
--
2.34.1

2022-04-22 21:02:37

by Aaron Tomlin

Subject: [PATCH v3 1/2] module: Make module_flags_taint() accept a module's taints bitmap directly

No functional change.

The purpose of this patch is to modify module_flags_taint() to accept a
module's taints bitmap as a parameter and modifies all users accordingly.
This is in preparation for module unload taint tracking support.

Signed-off-by: Aaron Tomlin <[email protected]>
---
kernel/module/main.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/module/main.c b/kernel/module/main.c
index 05a42d8fcd7a..ea78cec316dd 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -890,13 +890,13 @@ static inline int module_unload_init(struct module *mod)
}
#endif /* CONFIG_MODULE_UNLOAD */

-static size_t module_flags_taint(struct module *mod, char *buf)
+static size_t module_flags_taint(unsigned long taints, char *buf)
{
size_t l = 0;
int i;

for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
- if (taint_flags[i].module && test_bit(i, &mod->taints))
+ if (taint_flags[i].module && test_bit(i, &taints))
buf[l++] = taint_flags[i].c_true;
}

@@ -974,7 +974,7 @@ static ssize_t show_taint(struct module_attribute *mattr,
{
size_t l;

- l = module_flags_taint(mk->mod, buffer);
+ l = module_flags_taint(mk->mod->taints, buffer);
buffer[l++] = '\n';
return l;
}
@@ -2993,7 +2993,7 @@ char *module_flags(struct module *mod, char *buf)
mod->state == MODULE_STATE_GOING ||
mod->state == MODULE_STATE_COMING) {
buf[bx++] = '(';
- bx += module_flags_taint(mod, buf + bx);
+ bx += module_flags_taint(mod->taints, buf + bx);
/* Show a - for module-is-being-unloaded */
if (mod->state == MODULE_STATE_GOING)
buf[bx++] = '-';
--
2.34.1