gvisor.dev/gvisor@v0.0.0-20240520182842-f9d4d51c7e0f/pkg/sentry/mm/save_restore.go (about)

     1  // Copyright 2018 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package mm
    16  
    17  import (
    18  	goContext "context"
    19  	"fmt"
    20  
    21  	"gvisor.dev/gvisor/pkg/context"
    22  	"gvisor.dev/gvisor/pkg/sentry/pgalloc"
    23  )
    24  
    25  // InvalidateUnsavable invokes memmap.Mappable.InvalidateUnsavable on all
    26  // Mappables mapped by mm.
    27  func (mm *MemoryManager) InvalidateUnsavable(ctx context.Context) error {
    28  	mm.mappingMu.RLock()
    29  	defer mm.mappingMu.RUnlock()
    30  	for vseg := mm.vmas.FirstSegment(); vseg.Ok(); vseg = vseg.NextSegment() {
    31  		if vma := vseg.ValuePtr(); vma.mappable != nil {
    32  			if err := vma.mappable.InvalidateUnsavable(ctx); err != nil {
    33  				return err
    34  			}
    35  		}
    36  	}
    37  	return nil
    38  }
    39  
    40  // afterLoad is invoked by stateify.
    41  func (mm *MemoryManager) afterLoad(ctx goContext.Context) {
    42  	mm.mf = pgalloc.MemoryFileFromContext(ctx)
    43  	mm.haveASIO = mm.p.SupportsAddressSpaceIO()
    44  }
    45  
    46  // afterLoad is invoked by stateify.
    47  func (m *SpecialMappable) afterLoad(ctx goContext.Context) {
    48  	m.mf = pgalloc.MemoryFileFromContext(ctx)
    49  }
    50  
    51  const (
    52  	vmaRealPermsRead = 1 << iota
    53  	vmaRealPermsWrite
    54  	vmaRealPermsExecute
    55  	vmaEffectivePermsRead
    56  	vmaEffectivePermsWrite
    57  	vmaEffectivePermsExecute
    58  	vmaMaxPermsRead
    59  	vmaMaxPermsWrite
    60  	vmaMaxPermsExecute
    61  	vmaPrivate
    62  	vmaGrowsDown
    63  )
    64  
    65  func (v *vma) saveRealPerms() int {
    66  	var b int
    67  	if v.realPerms.Read {
    68  		b |= vmaRealPermsRead
    69  	}
    70  	if v.realPerms.Write {
    71  		b |= vmaRealPermsWrite
    72  	}
    73  	if v.realPerms.Execute {
    74  		b |= vmaRealPermsExecute
    75  	}
    76  	if v.effectivePerms.Read {
    77  		b |= vmaEffectivePermsRead
    78  	}
    79  	if v.effectivePerms.Write {
    80  		b |= vmaEffectivePermsWrite
    81  	}
    82  	if v.effectivePerms.Execute {
    83  		b |= vmaEffectivePermsExecute
    84  	}
    85  	if v.maxPerms.Read {
    86  		b |= vmaMaxPermsRead
    87  	}
    88  	if v.maxPerms.Write {
    89  		b |= vmaMaxPermsWrite
    90  	}
    91  	if v.maxPerms.Execute {
    92  		b |= vmaMaxPermsExecute
    93  	}
    94  	if v.private {
    95  		b |= vmaPrivate
    96  	}
    97  	if v.growsDown {
    98  		b |= vmaGrowsDown
    99  	}
   100  	return b
   101  }
   102  
   103  func (v *vma) loadRealPerms(_ goContext.Context, b int) {
   104  	if b&vmaRealPermsRead > 0 {
   105  		v.realPerms.Read = true
   106  	}
   107  	if b&vmaRealPermsWrite > 0 {
   108  		v.realPerms.Write = true
   109  	}
   110  	if b&vmaRealPermsExecute > 0 {
   111  		v.realPerms.Execute = true
   112  	}
   113  	if b&vmaEffectivePermsRead > 0 {
   114  		v.effectivePerms.Read = true
   115  	}
   116  	if b&vmaEffectivePermsWrite > 0 {
   117  		v.effectivePerms.Write = true
   118  	}
   119  	if b&vmaEffectivePermsExecute > 0 {
   120  		v.effectivePerms.Execute = true
   121  	}
   122  	if b&vmaMaxPermsRead > 0 {
   123  		v.maxPerms.Read = true
   124  	}
   125  	if b&vmaMaxPermsWrite > 0 {
   126  		v.maxPerms.Write = true
   127  	}
   128  	if b&vmaMaxPermsExecute > 0 {
   129  		v.maxPerms.Execute = true
   130  	}
   131  	if b&vmaPrivate > 0 {
   132  		v.private = true
   133  	}
   134  	if b&vmaGrowsDown > 0 {
   135  		v.growsDown = true
   136  	}
   137  }
   138  
   139  func (p *pma) saveFile() string {
   140  	mf, ok := p.file.(*pgalloc.MemoryFile)
   141  	if !ok {
   142  		// InvalidateUnsavable should have caused all such pmas to be
   143  		// invalidated.
   144  		panic(fmt.Sprintf("Can't save pma with non-MemoryFile of type %T", p.file))
   145  	}
   146  	if !mf.IsSavable() {
   147  		panic(fmt.Sprintf("Can't save pma because its MemoryFile is not savable: %v", mf))
   148  	}
   149  	return mf.RestoreID()
   150  }
   151  
   152  func (p *pma) loadFile(ctx goContext.Context, restoreID string) {
   153  	if restoreID == "" {
   154  		p.file = pgalloc.MemoryFileFromContext(ctx)
   155  		return
   156  	}
   157  	mfmap := pgalloc.MemoryFileMapFromContext(ctx)
   158  	mf, ok := mfmap[restoreID]
   159  	if !ok {
   160  		panic(fmt.Sprintf("can't restore pma because its MemoryFile's restore ID %q was not found in CtxMemoryFileMap", restoreID))
   161  	}
   162  	p.file = mf
   163  }