mseal() – Enhancing Memory Security in Linux Kernel 6.10

Functionality

• Introduces mseal(), a new syscall for the Linux kernel.
• Protects Virtual Memory Areas (VMAs) from unauthorized modifications.
• Introduced in Linux Kernel 6.10.

Security Enhancements

• Ensures read-only memory remains non-writable.
• Secures executable memory against unauthorized changes.

Compatibility

• Architecture-independent, supporting dynamic memory sealing.
• Useful for applications like Chrome’s control-flow integrity (CFI).
• Supports glibc's ELF executable loading.

Operations Blocking

• Blocks destructive operations like MADV_DONTNEED.

Overall Benefits

• Improves system security and resilience against vulnerabilities.

How to Use mseal()

Allocate Memory

void *addr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);        

Seal the Memory Using mseal()

int result = mseal(addr, size, MSEAL_SEAL); 
if (result != 0) { 
      perror("mseal failed"); 
}
int result = mseal(addr, size, MSEAL_SEAL);
if (result != 0) 
{ 
    perror("mseal failed");
 }        

Memory Access Control

The sealed memory will now be protected from unauthorized modifications.

Unseal the Memory (if necessary)

result = mseal(addr, size, MSEAL_UNSEAL); 
if (result != 0) 
{ 
    perror("mseal unseal failed");
 }        

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