Re: [PATCH] list module taint flags in Oops/panic
From: Florin Malita
Date: Mon Oct 02 2006 - 23:04:26 EST
Randy Dunlap wrote:
> From: Randy Dunlap <rdunlap@xxxxxxxxxxxx>
>
> When listing loaded modules during an oops or panic, also list each
> module's Tainted flags if non-zero (P: Proprietary or F: Forced load only).
>
Funny, I was playing with something very similar last weekend, then I
noticed your patch merged into mainline ;) So here are some comments...
> --- linux-2618-g10.orig/include/linux/module.h
> +++ linux-2618-g10/include/linux/module.h
> @@ -320,6 +320,8 @@ struct module
> /* Am I GPL-compatible */
> int license_gplok;
>
> + unsigned int taints; /* same bits as kernel:tainted */
>
No need to keep 'license_gplok' around anymore, it should be equivalent
to !(taints & TAINT_PROPRIETARY_MODULE).
> @@ -851,6 +851,7 @@ static int check_version(Elf_Shdr *sechd
> printk("%s: no version for \"%s\" found: kernel tainted.\n",
> mod->name, symname);
> add_taint(TAINT_FORCED_MODULE);
> + mod->taints |= TAINT_FORCED_MODULE;
> }
>
This seems wrong, it only dirties mod->taints if the kernel is not
already F-tainted (the branch is conditioned by !(tainted &
TAINT_FORCED_MODULE)). So only the first forcefully-loaded module gets
its F bit set, which is probably not the intention...
> @@ -1325,6 +1326,7 @@ static void set_license(struct module *m
> printk(KERN_WARNING "%s: module license '%s' taints kernel.\n",
> mod->name, license);
> add_taint(TAINT_PROPRIETARY_MODULE);
> + mod->taints |= TAINT_PROPRIETARY_MODULE;
> }
>
Similarly here, will only take the branch upon loading the first
proprietary module (conditional on !(tainted & TAINT_PROPRIETARY_MODULE)).
The currently merged version also has a problem in taint_flags():
static char *taint_flags(unsigned int taints, char *buf)
{
*buf = '\0';
if (taints) {
int bx;
buf[0] = '(';
bx = 1;
if (taints & TAINT_PROPRIETARY_MODULE)
buf[bx++] = 'P';
if (taints & TAINT_FORCED_MODULE)
buf[bx++] = 'F';
/*
* TAINT_FORCED_RMMOD: could be added.
* TAINT_UNSAFE_SMP, TAINT_MACHINE_CHECK, TAINT_BAD_PAGE
don't
* apply to modules.
*/
buf[bx] = ')';
}
return buf;
}
The buffer is not NULL-terminated after printing the flags.
Also, it would be nice to show per-module taint info in /proc/modules
too. So how about the following (applies on top of the merged
version/current git, tested):
Signed-off-by: Florin Malita <fmalita@xxxxxxxxx>
---
include/linux/module.h | 3 -
kernel/module.c | 94 +++++++++++++++++++++++++------------------------
2 files changed, 49 insertions(+), 48 deletions(-)
diff --git a/include/linux/module.h b/include/linux/module.h
index 4b2d809..d1d00ce 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -317,9 +317,6 @@ struct module
/* Am I unsafe to unload? */
int unsafe;
- /* Am I GPL-compatible */
- int license_gplok;
-
unsigned int taints; /* same bits as kernel:tainted */
#ifdef CONFIG_MODULE_UNLOAD
diff --git a/kernel/module.c b/kernel/module.c
index 7c77a0a..a258cd5 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -87,6 +87,12 @@ static inline int strong_try_module_get(
return try_module_get(mod);
}
+static inline void add_taint_module(struct module *mod, unsigned flag)
+{
+ add_taint(flag);
+ mod->taints |= flag;
+}
+
/* A thread that wants to hold a reference to a module only while it
* is running can call ths to safely exit.
* nfsd and lockd use this.
@@ -847,12 +853,10 @@ static int check_version(Elf_Shdr *sechd
return 0;
}
/* Not in module's version table. OK, but that taints the kernel. */
- if (!(tainted & TAINT_FORCED_MODULE)) {
+ if (!(tainted & TAINT_FORCED_MODULE))
printk("%s: no version for \"%s\" found: kernel tainted.\n",
mod->name, symname);
- add_taint(TAINT_FORCED_MODULE);
- mod->taints |= TAINT_FORCED_MODULE;
- }
+ add_taint_module(mod, TAINT_FORCED_MODULE);
return 1;
}
@@ -910,7 +914,8 @@ static unsigned long resolve_symbol(Elf_
unsigned long ret;
const unsigned long *crc;
- ret = __find_symbol(name, &owner, &crc, mod->license_gplok);
+ ret = __find_symbol(name, &owner, &crc,
+ !(mod->taints & TAINT_PROPRIETARY_MODULE));
if (ret) {
/* use_module can fail due to OOM, or module unloading */
if (!check_version(sechdrs, versindex, name, mod, crc) ||
@@ -1335,12 +1340,11 @@ static void set_license(struct module *m
if (!license)
license = "unspecified";
- mod->license_gplok = license_is_gpl_compatible(license);
- if (!mod->license_gplok && !(tainted & TAINT_PROPRIETARY_MODULE)) {
- printk(KERN_WARNING "%s: module license '%s' taints kernel.\n",
- mod->name, license);
- add_taint(TAINT_PROPRIETARY_MODULE);
- mod->taints |= TAINT_PROPRIETARY_MODULE;
+ if (!license_is_gpl_compatible(license)) {
+ if (!(tainted & TAINT_PROPRIETARY_MODULE))
+ printk(KERN_WARNING "%s: module license '%s' taints"
+ "kernel.\n", mod->name, license);
+ add_taint_module(mod, TAINT_PROPRIETARY_MODULE);
}
}
@@ -1619,8 +1623,7 @@ #endif
modmagic = get_modinfo(sechdrs, infoindex, "vermagic");
/* This is allowed: modprobe --force will invalidate it. */
if (!modmagic) {
- add_taint(TAINT_FORCED_MODULE);
- mod->taints |= TAINT_FORCED_MODULE;
+ add_taint_module(mod, TAINT_FORCED_MODULE);
printk(KERN_WARNING "%s: no version magic, tainting kernel.\n",
mod->name);
} else if (!same_magic(modmagic, vermagic)) {
@@ -1714,14 +1717,10 @@ #endif
/* Set up license info based on the info section */
set_license(mod, get_modinfo(sechdrs, infoindex, "license"));
- if (strcmp(mod->name, "ndiswrapper") == 0) {
- add_taint(TAINT_PROPRIETARY_MODULE);
- mod->taints |= TAINT_PROPRIETARY_MODULE;
- }
- if (strcmp(mod->name, "driverloader") == 0) {
- add_taint(TAINT_PROPRIETARY_MODULE);
- mod->taints |= TAINT_PROPRIETARY_MODULE;
- }
+ if (strcmp(mod->name, "ndiswrapper") == 0)
+ add_taint_module(mod, TAINT_PROPRIETARY_MODULE);
+ if (strcmp(mod->name, "driverloader") == 0)
+ add_taint_module(mod, TAINT_PROPRIETARY_MODULE);
/* Set up MODINFO_ATTR fields */
setup_modinfo(mod, sechdrs, infoindex);
@@ -1766,8 +1765,7 @@ #ifdef CONFIG_MODVERSIONS
(mod->num_unused_gpl_syms && !unusedgplcrcindex)) {
printk(KERN_WARNING "%s: No versions for exported symbols."
" Tainting kernel.\n", mod->name);
- add_taint(TAINT_FORCED_MODULE);
- mod->taints |= TAINT_FORCED_MODULE;
+ add_taint_module(mod, TAINT_FORCED_MODULE);
}
#endif
@@ -2131,9 +2129,33 @@ static void m_stop(struct seq_file *m, v
mutex_unlock(&module_mutex);
}
+static char *taint_flags(unsigned int taints, char *buf)
+{
+ int bx = 0;
+
+ if (taints) {
+ buf[bx++] = '(';
+ if (taints & TAINT_PROPRIETARY_MODULE)
+ buf[bx++] = 'P';
+ if (taints & TAINT_FORCED_MODULE)
+ buf[bx++] = 'F';
+ /*
+ * TAINT_FORCED_RMMOD: could be added.
+ * TAINT_UNSAFE_SMP, TAINT_MACHINE_CHECK, TAINT_BAD_PAGE don't
+ * apply to modules.
+ */
+ buf[bx++] = ')';
+ }
+ buf[bx] = '\0';
+
+ return buf;
+}
+
static int m_show(struct seq_file *m, void *p)
{
struct module *mod = list_entry(p, struct module, list);
+ char buf[8];
+
seq_printf(m, "%s %lu",
mod->name, mod->init_size + mod->core_size);
print_unload_info(m, mod);
@@ -2146,6 +2168,10 @@ static int m_show(struct seq_file *m, vo
/* Used by oprofile and other similar tools. */
seq_printf(m, " 0x%p", mod->module_core);
+ /* Taints info */
+ if (mod->taints)
+ seq_printf(m, " %s", taint_flags(mod->taints, buf));
+
seq_printf(m, "\n");
return 0;
}
@@ -2234,28 +2260,6 @@ struct module *module_text_address(unsig
return mod;
}
-static char *taint_flags(unsigned int taints, char *buf)
-{
- *buf = '\0';
- if (taints) {
- int bx;
-
- buf[0] = '(';
- bx = 1;
- if (taints & TAINT_PROPRIETARY_MODULE)
- buf[bx++] = 'P';
- if (taints & TAINT_FORCED_MODULE)
- buf[bx++] = 'F';
- /*
- * TAINT_FORCED_RMMOD: could be added.
- * TAINT_UNSAFE_SMP, TAINT_MACHINE_CHECK, TAINT_BAD_PAGE don't
- * apply to modules.
- */
- buf[bx] = ')';
- }
- return buf;
-}
-
/* Don't grab lock, we're oopsing. */
void print_modules(void)
{
-
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