From 20279c305ece6a458006999c8dafc5672ca92803 Mon Sep 17 00:00:00 2001 From: Ian Lewis Date: Tue, 26 Nov 2019 18:19:47 -0800 Subject: Allow open(O_TRUNC) and (f)truncate for proc files. This allows writable proc and devices files to be opened with O_CREAT|O_TRUNC. This is encountered most frequently when interacting with proc or devices files via the command line. e.g. $ echo 8192 1048576 4194304 > /proc/sys/net/ipv4/tcp_rmem Also adds a test to test the behavior of open(O_TRUNC), truncate, and ftruncate on named pipes. Fixes #1116 PiperOrigin-RevId: 282677425 --- pkg/sentry/fs/tty/master.go | 6 +++++- pkg/sentry/fs/tty/slave.go | 6 +++++- 2 files changed, 10 insertions(+), 2 deletions(-) (limited to 'pkg/sentry/fs/tty') diff --git a/pkg/sentry/fs/tty/master.go b/pkg/sentry/fs/tty/master.go index bc56be696..934828c12 100644 --- a/pkg/sentry/fs/tty/master.go +++ b/pkg/sentry/fs/tty/master.go @@ -32,7 +32,6 @@ import ( // +stateify savable type masterInodeOperations struct { fsutil.SimpleFileInode - fsutil.InodeNoopTruncate // d is the containing dir. d *dirInodeOperations @@ -77,6 +76,11 @@ func newMasterInode(ctx context.Context, d *dirInodeOperations, owner fs.FileOwn func (mi *masterInodeOperations) Release(ctx context.Context) { } +// Truncate implements fs.InodeOperations.Truncate. +func (masterInodeOperations) Truncate(context.Context, *fs.Inode, int64) error { + return nil +} + // GetFile implements fs.InodeOperations.GetFile. // // It allocates a new terminal. diff --git a/pkg/sentry/fs/tty/slave.go b/pkg/sentry/fs/tty/slave.go index 4cbea0367..2a51e6bab 100644 --- a/pkg/sentry/fs/tty/slave.go +++ b/pkg/sentry/fs/tty/slave.go @@ -31,7 +31,6 @@ import ( // +stateify savable type slaveInodeOperations struct { fsutil.SimpleFileInode - fsutil.InodeNoopTruncate // d is the containing dir. d *dirInodeOperations @@ -73,6 +72,11 @@ func (si *slaveInodeOperations) Release(ctx context.Context) { si.t.DecRef() } +// Truncate implements fs.InodeOperations.Truncate. +func (slaveInodeOperations) Truncate(context.Context, *fs.Inode, int64) error { + return nil +} + // GetFile implements fs.InodeOperations.GetFile. // // This may race with destruction of the terminal. If the terminal is gone, it -- cgit v1.2.3