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| author | Kees Cook <keescook@chromium.org> | 2020-07-02 23:43:59 +0200 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2020-07-09 01:00:19 +0200 |
| commit | b25a7c5af9051850d4f3d93ca500056ab6ec724b (patch) | |
| tree | 7b08c4c227a9299a22e0b006a74b11a4729c32cd | |
| parent | module: Refactor section attr into bin attribute (diff) | |
| download | linux-b25a7c5af9051850d4f3d93ca500056ab6ec724b.tar.xz linux-b25a7c5af9051850d4f3d93ca500056ab6ec724b.zip | |
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>
| -rw-r--r-- | kernel/module.c | 6 |
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; |