From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Convert 'same_path()' so that it works when 'rootdir'
is set in the [exports] section of nfs.conf.
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
---
utils/mountd/cache.c | 83 +++++++++++++++++++++++++++++++-------------
1 file changed, 59 insertions(+), 24 deletions(-)
diff --git a/utils/mountd/cache.c b/utils/mountd/cache.c
index 7d8657c91323..94e9e44b46b9 100644
--- a/utils/mountd/cache.c
+++ b/utils/mountd/cache.c
@@ -72,6 +72,18 @@ static ssize_t cache_write(int fd, const char *buf, size_t len)
return nfsd_path_write(fd, buf, len);
}
+static bool path_lookup_error(int err)
+{
+ switch (err) {
+ case ELOOP:
+ case ENAMETOOLONG:
+ case ENOENT:
+ case ENOTDIR:
+ return 1;
+ }
+ return 0;
+}
+
/*
* Support routines for text-based upcalls.
* Fields are separated by spaces.
@@ -430,23 +442,9 @@ static inline int count_slashes(char *p)
return cnt;
}
-static int same_path(char *child, char *parent, int len)
+#if defined(HAVE_STRUCT_FILE_HANDLE)
+static int check_same_path_by_handle(const char *child, const char *parent)
{
- static char p[PATH_MAX];
- struct stat sc, sp;
-
- if (len <= 0)
- len = strlen(child);
- strncpy(p, child, len);
- p[len] = 0;
- if (strcmp(p, parent) == 0)
- return 1;
-
- /* If number of '/' are different, they must be different */
- if (count_slashes(p) != count_slashes(parent))
- return 0;
-
-#if defined(HAVE_NAME_TO_HANDLE_AT) && defined(HAVE_STRUCT_FILE_HANDLE)
struct {
struct file_handle fh;
unsigned char handle[128];
@@ -455,13 +453,17 @@ static int same_path(char *child, char *parent, int len)
fchild.fh.handle_bytes = 128;
fparent.fh.handle_bytes = 128;
- if (name_to_handle_at(AT_FDCWD, p, &fchild.fh, &mnt_child, 0) != 0) {
- if (errno == ENOSYS)
- goto fallback;
- return 0;
+
+ /* This process should have the CAP_DAC_READ_SEARCH capability */
+ if (nfsd_name_to_handle_at(AT_FDCWD, child, &fchild.fh, &mnt_child, 0) < 0)
+ return -1;
+ if (nfsd_name_to_handle_at(AT_FDCWD, parent, &fparent.fh, &mnt_parent, 0) < 0) {
+ /* If the child resolved, but the parent did not, they differ */
+ if (path_lookup_error(errno))
+ return 0;
+ /* Otherwise, we just don't know */
+ return -1;
}
- if (name_to_handle_at(AT_FDCWD, parent, &fparent.fh, &mnt_parent, 0) != 0)
- return 0;
if (mnt_child != mnt_parent ||
fchild.fh.handle_bytes != fparent.fh.handle_bytes ||
@@ -471,14 +473,24 @@ static int same_path(char *child, char *parent, int len)
return 0;
return 1;
-fallback:
+}
+#else
+static int check_same_path_by_handle(const char *child, const char *parent)
+{
+ errno = ENOSYS;
+ return -1;
+}
#endif
+static int check_same_path_by_inode(const char *child, const char *parent)
+{
+ struct stat sc, sp;
+
/* This is nearly good enough. However if a directory is
* bind-mounted in two places and both are exported, it
* could give a false positive
*/
- if (nfsd_path_lstat(p, &sc) != 0)
+ if (nfsd_path_lstat(child, &sc) != 0)
return 0;
if (nfsd_path_lstat(parent, &sp) != 0)
return 0;
@@ -490,6 +502,29 @@ fallback:
return 1;
}
+static int same_path(char *child, char *parent, int len)
+{
+ static char p[PATH_MAX];
+ int err;
+
+ if (len <= 0)
+ len = strlen(child);
+ strncpy(p, child, len);
+ p[len] = 0;
+ if (strcmp(p, parent) == 0)
+ return 1;
+
+ /* If number of '/' are different, they must be different */
+ if (count_slashes(p) != count_slashes(parent))
+ return 0;
+
+ /* Try to use filehandle approach before falling back to stat() */
+ err = check_same_path_by_handle(p, parent);
+ if (err != -1)
+ return err;
+ return check_same_path_by_inode(p, parent);
+}
+
static int is_subdirectory(char *child, char *parent)
{
/* Check is child is strictly a subdirectory of
--
2.25.2
