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| author | Quentin Monnet <quentin.monnet@netronome.com> | 2018-03-09 10:46:33 +0300 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2018-03-09 12:30:30 +0300 |
| commit | 6d8cb045cde681e64a5ed80a2ab70be831a7f9b0 (patch) | |
| tree | 56d5def14c5a60f3b58a6f696ba1f5528b3c9403 /kernel/bpf/inode.c | |
| parent | 75a141af68c5507727e0f4c41f8e3dd54de96fed (diff) | |
| download | linux-6d8cb045cde681e64a5ed80a2ab70be831a7f9b0.tar.xz | |
bpf: comment why dots in filenames under BPF virtual FS are not allowed
When pinning a file under the BPF virtual file system (traditionally
/sys/fs/bpf), using a dot in the name of the location to pin at is not
allowed. For example, trying to pin at "/sys/fs/bpf/foo.bar" will be
rejected with -EPERM.
This check was introduced at the same time as the BPF file system
itself, with commit b2197755b263 ("bpf: add support for persistent
maps/progs"). At this time, it was checked in a function called
"bpf_dname_reserved()", which made clear that using a dot was reserved
for future extensions.
This function disappeared and the check was moved elsewhere with commit
0c93b7d85d40 ("bpf: reject invalid names right in ->lookup()"), and the
meaning of the dot ban was lost.
The present commit simply adds a comment in the source to explain to the
reader that the usage of dots is reserved for future usage.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'kernel/bpf/inode.c')
| -rw-r--r-- | kernel/bpf/inode.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c index 81e2f6995adb..bf6da59ae0d0 100644 --- a/kernel/bpf/inode.c +++ b/kernel/bpf/inode.c @@ -178,6 +178,9 @@ static int bpf_mkmap(struct dentry *dentry, umode_t mode, void *arg) static struct dentry * bpf_lookup(struct inode *dir, struct dentry *dentry, unsigned flags) { + /* Dots in names (e.g. "/sys/fs/bpf/foo.bar") are reserved for future + * extensions. + */ if (strchr(dentry->d_name.name, '.')) return ERR_PTR(-EPERM); |