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Subject[PATCH 01/13] vfs: verify param type in vfs_parse_sb_flag()
Date
vfs_parse_sb_flag() accepted any kind of param with a matching key, not
just a flag. This is wrong, only allow flag type and return -EINVAL
otherwise.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
fs/fs_context.c | 31 +++++++++++++++----------------
1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/fs/fs_context.c b/fs/fs_context.c
index 103643c68e3f..e56310fd8c75 100644
--- a/fs/fs_context.c
+++ b/fs/fs_context.c
@@ -81,30 +81,29 @@ static const char *const forbidden_sb_flag[] = {
/*
* Check for a common mount option that manipulates s_flags.
*/
-static int vfs_parse_sb_flag(struct fs_context *fc, const char *key)
+static int vfs_parse_sb_flag(struct fs_context *fc, struct fs_parameter *param)
{
- unsigned int token;
+ const char *key = param->key;
+ unsigned int set, clear;
unsigned int i;

for (i = 0; i < ARRAY_SIZE(forbidden_sb_flag); i++)
if (strcmp(key, forbidden_sb_flag[i]) == 0)
return -EINVAL;

- token = lookup_constant(common_set_sb_flag, key, 0);
- if (token) {
- fc->sb_flags |= token;
- fc->sb_flags_mask |= token;
- return 0;
- }
+ set = lookup_constant(common_set_sb_flag, key, 0);
+ clear = lookup_constant(common_clear_sb_flag, key, 0);
+ if (!set && !clear)
+ return -ENOPARAM;

- token = lookup_constant(common_clear_sb_flag, key, 0);
- if (token) {
- fc->sb_flags &= ~token;
- fc->sb_flags_mask |= token;
- return 0;
- }
+ if (param->type != fs_value_is_flag)
+ return invalf(fc, "%s: Unexpected value for '%s'",
+ fc->fs_type->name, param->key);

- return -ENOPARAM;
+ fc->sb_flags |= set;
+ fc->sb_flags &= ~clear;
+ fc->sb_flags_mask |= set | clear;
+ return 0;
}

/**
@@ -130,7 +129,7 @@ int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param)
if (!param->key)
return invalf(fc, "Unnamed parameter\n");

- ret = vfs_parse_sb_flag(fc, param->key);
+ ret = vfs_parse_sb_flag(fc, param);
if (ret != -ENOPARAM)
return ret;

--
2.21.0
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