diff options
| -rw-r--r-- | pkg/abi/linux/shm.go | 11 | ||||
| -rw-r--r-- | pkg/sentry/fs/proc/sys.go | 6 | ||||
| -rw-r--r-- | pkg/sentry/kernel/shm/shm.go | 34 |
3 files changed, 25 insertions, 26 deletions
diff --git a/pkg/abi/linux/shm.go b/pkg/abi/linux/shm.go index 9149ed094..f50b3c2e2 100644 --- a/pkg/abi/linux/shm.go +++ b/pkg/abi/linux/shm.go @@ -14,6 +14,8 @@ package linux +import "math" + // shmat(2) flags. Source: include/uapi/linux/shm.h const ( SHM_RDONLY = 010000 // Read-only access. @@ -38,6 +40,15 @@ const ( SHM_INFO = 14 ) +// SHM defaults as specified by linux. Source: include/uapi/linux/shm.h +const ( + SHMMIN = 1 + SHMMNI = 4096 + SHMMAX = math.MaxUint64 - 1<<24 + SHMALL = math.MaxUint64 - 1<<24 + SHMSEG = 4096 +) + // ShmidDS is equivalent to struct shmid64_ds. Source: // include/uapi/asm-generic/shmbuf.h type ShmidDS struct { diff --git a/pkg/sentry/fs/proc/sys.go b/pkg/sentry/fs/proc/sys.go index a2d36ca23..384b4ffe1 100644 --- a/pkg/sentry/fs/proc/sys.go +++ b/pkg/sentry/fs/proc/sys.go @@ -17,7 +17,9 @@ package proc import ( "fmt" "io" + "strconv" + "gvisor.googlesource.com/gvisor/pkg/abi/linux" "gvisor.googlesource.com/gvisor/pkg/sentry/context" "gvisor.googlesource.com/gvisor/pkg/sentry/fs" "gvisor.googlesource.com/gvisor/pkg/sentry/fs/proc/seqfile" @@ -102,6 +104,10 @@ func (p *proc) newKernelDir(ctx context.Context, msrc *fs.MountSource) *fs.Inode d := &ramfs.Dir{} d.InitDir(ctx, nil, fs.RootOwner, fs.FilePermsFromMode(0555)) d.AddChild(ctx, "hostname", p.newHostname(ctx, msrc)) + + d.AddChild(ctx, "shmmax", p.newStubProcFSFile(ctx, msrc, []byte(strconv.FormatUint(linux.SHMMAX, 10)))) + d.AddChild(ctx, "shmall", p.newStubProcFSFile(ctx, msrc, []byte(strconv.FormatUint(linux.SHMALL, 10)))) + d.AddChild(ctx, "shmmni", p.newStubProcFSFile(ctx, msrc, []byte(strconv.FormatUint(linux.SHMMNI, 10)))) return newFile(d, msrc, fs.SpecialDirectory, nil) } diff --git a/pkg/sentry/kernel/shm/shm.go b/pkg/sentry/kernel/shm/shm.go index 1ac444094..77973951e 100644 --- a/pkg/sentry/kernel/shm/shm.go +++ b/pkg/sentry/kernel/shm/shm.go @@ -35,7 +35,6 @@ package shm import ( "fmt" - "math" "sync" "gvisor.googlesource.com/gvisor/pkg/abi/linux" @@ -52,23 +51,6 @@ import ( "gvisor.googlesource.com/gvisor/pkg/syserror" ) -// Various limits for shared memory segments. -const ( - // shmsTotalMaxPages is the system-wide limit on all shared memory segments, measured - // in number of pages. - shmsTotalMaxPages = math.MaxInt64 // SHMALL - - // shmMaxSize is the maximum size of a single segment, in bytes. - shmMaxSize = math.MaxInt64 // SHMMAX - - // shmMinSize is the minimum specifiable size of a segment, effectively - // yielding a size rounded up to the next page size. Measured in bytes. - shmMinSize = 1 // SHMMIN - - // shmsTotalMax is the maximum number of segments on the system. - shmsTotalMax = 4096 // SHMMNI -) - // Registry tracks all shared memory segments in an IPC namespace. The registry // provides the mechanisms for creating and finding segments, and reporting // global shm parameters. @@ -119,7 +101,7 @@ func (r *Registry) findByKey(key int32) *Shm { // FindOrCreate looks up or creates a segment in the registry. It's functionally // analogous to open(2). func (r *Registry) FindOrCreate(ctx context.Context, pid, key int32, size uint64, mode linux.FileMode, private, create, exclusive bool) (*Shm, error) { - if create && (size < shmMinSize || size > shmMaxSize) { + if create && (size < linux.SHMMIN || size > linux.SHMMAX) { // "A new segment was to be created and size is less than SHMMIN or // greater than SHMMAX." - man shmget(2) return nil, syserror.EINVAL @@ -128,7 +110,7 @@ func (r *Registry) FindOrCreate(ctx context.Context, pid, key int32, size uint64 r.mu.Lock() defer r.mu.Unlock() - if len(r.shms) >= shmsTotalMax { + if len(r.shms) >= linux.SHMMNI { // "All possible shared memory IDs have been taken (SHMMNI) ..." // - man shmget(2) return nil, syserror.ENOSPC @@ -179,7 +161,7 @@ func (r *Registry) FindOrCreate(ctx context.Context, pid, key int32, size uint64 return nil, syserror.EINVAL } - if numPages := sizeAligned / usermem.PageSize; r.totalPages+numPages > shmsTotalMaxPages { + if numPages := sizeAligned / usermem.PageSize; r.totalPages+numPages > linux.SHMALL { // "... allocating a segment of the requested size would cause the // system to exceed the system-wide limit on shared memory (SHMALL)." // - man shmget(2) @@ -245,11 +227,11 @@ func (r *Registry) newShm(ctx context.Context, pid, key int32, creator fs.FileOw // system. See shmctl(IPC_INFO). func (r *Registry) IPCInfo() *linux.ShmParams { return &linux.ShmParams{ - ShmMax: shmMaxSize, - ShmMin: shmMinSize, - ShmMni: shmsTotalMax, - ShmSeg: shmsTotalMax, // Linux also sets this to SHMMNI. - ShmAll: shmsTotalMaxPages, + ShmMax: linux.SHMMAX, + ShmMin: linux.SHMMIN, + ShmMni: linux.SHMMNI, + ShmSeg: linux.SHMSEG, + ShmAll: linux.SHMALL, } } |