From 49a76d7040b466dd92f198ded4aba3cd3569d48f Mon Sep 17 00:00:00 2001 From: Oleg Drokin Date: Sat, 6 Feb 2016 02:01:50 -0500 Subject: [PATCH] staging/lustre/libcfs: Properly handle debugfs read- and write-only files It turns out that unlike procfs, debugfs does not really enforce permissions for root (similar to regular filesystems), so we need to ensure we are not providing ->write() method to read-only files and ->read() method for write-only files at registration. This fixes a couple of crashes on unexpected access. Signed-off-by: Oleg Drokin Signed-off-by: Greg Kroah-Hartman --- drivers/staging/lustre/lustre/libcfs/module.c | 27 +++++++++++++++++-- 1 file changed, 25 insertions(+), 2 deletions(-) diff --git a/drivers/staging/lustre/lustre/libcfs/module.c b/drivers/staging/lustre/lustre/libcfs/module.c index d5a047bd0180..611607ab92db 100644 --- a/drivers/staging/lustre/lustre/libcfs/module.c +++ b/drivers/staging/lustre/lustre/libcfs/module.c @@ -502,13 +502,36 @@ static ssize_t lnet_debugfs_write(struct file *filp, const char __user *buf, return error; } -static const struct file_operations lnet_debugfs_file_operations = { +static const struct file_operations lnet_debugfs_file_operations_rw = { .open = simple_open, .read = lnet_debugfs_read, .write = lnet_debugfs_write, .llseek = default_llseek, }; +static const struct file_operations lnet_debugfs_file_operations_ro = { + .open = simple_open, + .read = lnet_debugfs_read, + .llseek = default_llseek, +}; + +static const struct file_operations lnet_debugfs_file_operations_wo = { + .open = simple_open, + .write = lnet_debugfs_write, + .llseek = default_llseek, +}; + +static const struct file_operations *lnet_debugfs_fops_select(umode_t mode) +{ + if (!(mode & S_IWUGO)) + return &lnet_debugfs_file_operations_ro; + + if (!(mode & S_IRUGO)) + return &lnet_debugfs_file_operations_wo; + + return &lnet_debugfs_file_operations_rw; +} + void lustre_insert_debugfs(struct ctl_table *table, const struct lnet_debugfs_symlink_def *symlinks) { @@ -525,7 +548,7 @@ void lustre_insert_debugfs(struct ctl_table *table, for (; table->procname; table++) debugfs_create_file(table->procname, table->mode, lnet_debugfs_root, table, - &lnet_debugfs_file_operations); + lnet_debugfs_fops_select(table->mode)); for (; symlinks && symlinks->name; symlinks++) debugfs_create_symlink(symlinks->name, lnet_debugfs_root, -- 2.30.2