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authorKees Cook <keescook@chromium.org>2020-07-02 14:43:59 -0700
committerKees Cook <keescook@chromium.org>2020-07-08 16:00:19 -0700
commitb25a7c5af9051850d4f3d93ca500056ab6ec724b (patch)
tree7b08c4c227a9299a22e0b006a74b11a4729c32cd /kernel
parented66f991bb19d94cae5d38f77de81f96aac7813f (diff)
module: Do not expose section addresses to non-CAP_SYSLOG
The printing of section addresses in /sys/module/*/sections/* was not using the correct credentials to evaluate visibility. Before: # cat /sys/module/*/sections/.*text 0xffffffffc0458000 ... # capsh --drop=CAP_SYSLOG -- -c "cat /sys/module/*/sections/.*text" 0xffffffffc0458000 ... After: # cat /sys/module/*/sections/*.text 0xffffffffc0458000 ... # capsh --drop=CAP_SYSLOG -- -c "cat /sys/module/*/sections/.*text" 0x0000000000000000 ... Additionally replaces the existing (safe) /proc/modules check with file->f_cred for consistency. Reported-by: Dominik Czarnota <dominik.czarnota@trailofbits.com> Fixes: be71eda5383f ("module: Fix display of wrong module .text address") Cc: stable@vger.kernel.org Tested-by: Jessica Yu <jeyu@kernel.org> Acked-by: Jessica Yu <jeyu@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/module.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/module.c b/kernel/module.c
index 9e2954519259..e6c7571092cb 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1530,8 +1530,8 @@ static ssize_t module_sect_read(struct file *file, struct kobject *kobj,
if (pos != 0)
return -EINVAL;
- return sprintf(buf, "0x%px\n", kptr_restrict < 2 ?
- (void *)sattr->address : NULL);
+ return sprintf(buf, "0x%px\n",
+ kallsyms_show_value(file->f_cred) ? (void *)sattr->address : NULL);
}
static void free_sect_attrs(struct module_sect_attrs *sect_attrs)
@@ -4380,7 +4380,7 @@ static int modules_open(struct inode *inode, struct file *file)
if (!err) {
struct seq_file *m = file->private_data;
- m->private = kallsyms_show_value(current_cred()) ? NULL : (void *)8ul;
+ m->private = kallsyms_show_value(file->f_cred) ? NULL : (void *)8ul;
}
return err;