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authorLennart Poettering <lennart@poettering.net>2015-04-22 13:05:26 +0200
committerLennart Poettering <lennart@poettering.net>2015-04-22 13:27:53 +0200
commit03091baac3c37094af6a30be31e4962dd26f8404 (patch)
tree242e6ca2dcd35e96038e14663a673e3d30bf19c6 /src
parent163ab2961268232e1cb49e990a8ccefe24b7649f (diff)
util: make sure fd refers to regular file or directory when applying file attributes
Before invoking file system ioctls we need to make sure that the specified fd actually refers to a file system object, and not a device node or similar. Otherwise we might by accident invoke unrelated device driver ioctls. For example, DRM ioctls use the same ioctl numbers as the various file system ioctls.
Diffstat (limited to 'src')
-rw-r--r--src/shared/util.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/src/shared/util.c b/src/shared/util.c
index f14d9ee90b..4a044840bd 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -5988,9 +5988,22 @@ int same_fd(int a, int b) {
int chattr_fd(int fd, unsigned value, unsigned mask) {
unsigned old_attr, new_attr;
+ struct stat st;
assert(fd >= 0);
+ if (fstat(fd, &st) < 0)
+ return -errno;
+
+ /* Explicitly check whether this is a regular file or
+ * directory. If it is anything else (such as a device node or
+ * fifo), then the ioctl will not hit the file systems but
+ * possibly drivers, where the ioctl might have different
+ * effects. Notably, DRM is using the same ioctl() number. */
+
+ if (!S_ISDIR(st.st_mode) && !S_ISREG(st.st_mode))
+ return -ENOTTY;
+
if (mask == 0)
return 0;
@@ -6023,8 +6036,16 @@ int chattr_path(const char *p, unsigned value, unsigned mask) {
}
int read_attr_fd(int fd, unsigned *ret) {
+ struct stat st;
+
assert(fd >= 0);
+ if (fstat(fd, &st) < 0)
+ return -errno;
+
+ if (!S_ISDIR(st.st_mode) && !S_ISREG(st.st_mode))
+ return -ENOTTY;
+
if (ioctl(fd, FS_IOC_GETFLAGS, ret) < 0)
return -errno;