diff options
Diffstat (limited to 'fs/binfmt_elf.c')
| -rw-r--r-- | fs/binfmt_elf.c | 101 |
1 files changed, 67 insertions, 34 deletions
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index a43897b03ce9..5ae8045f4df4 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -1003,7 +1003,8 @@ out_free_interp: if (elf_read_implies_exec(*elf_ex, executable_stack)) current->personality |= READ_IMPLIES_EXEC; - if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) + const int snapshot_randomize_va_space = READ_ONCE(randomize_va_space); + if (!(current->personality & ADDR_NO_RANDOMIZE) && snapshot_randomize_va_space) current->flags |= PF_RANDOMIZE; setup_new_exec(bprm); @@ -1061,10 +1062,40 @@ out_free_interp: * Header for ET_DYN binaries to calculate the * randomization (load_bias) for all the LOAD * Program Headers. + */ + + /* + * Calculate the entire size of the ELF mapping + * (total_size), used for the initial mapping, + * due to load_addr_set which is set to true later + * once the initial mapping is performed. + * + * Note that this is only sensible when the LOAD + * segments are contiguous (or overlapping). If + * used for LOADs that are far apart, this would + * cause the holes between LOADs to be mapped, + * running the risk of having the mapping fail, + * as it would be larger than the ELF file itself. * + * As a result, only ET_DYN does this, since + * some ET_EXEC (e.g. ia64) may have large virtual + * memory holes between LOADs. + * + */ + total_size = total_mapping_size(elf_phdata, + elf_ex->e_phnum); + if (!total_size) { + retval = -EINVAL; + goto out_free_dentry; + } + + /* Calculate any requested alignment. */ + alignment = maximum_alignment(elf_phdata, elf_ex->e_phnum); + + /* * There are effectively two types of ET_DYN - * binaries: programs (i.e. PIE: ET_DYN with INTERP) - * and loaders (ET_DYN without INTERP, since they + * binaries: programs (i.e. PIE: ET_DYN with PT_INTERP) + * and loaders (ET_DYN without PT_INTERP, since they * _are_ the ELF interpreter). The loaders must * be loaded away from programs since the program * may otherwise collide with the loader (especially @@ -1084,15 +1115,44 @@ out_free_interp: * without MAP_FIXED nor MAP_FIXED_NOREPLACE). */ if (interpreter) { + /* On ET_DYN with PT_INTERP, we do the ASLR. */ load_bias = ELF_ET_DYN_BASE; if (current->flags & PF_RANDOMIZE) load_bias += arch_mmap_rnd(); - alignment = maximum_alignment(elf_phdata, elf_ex->e_phnum); + /* Adjust alignment as requested. */ if (alignment) load_bias &= ~(alignment - 1); elf_flags |= MAP_FIXED_NOREPLACE; - } else - load_bias = 0; + } else { + /* + * For ET_DYN without PT_INTERP, we rely on + * the architectures's (potentially ASLR) mmap + * base address (via a load_bias of 0). + * + * When a large alignment is requested, we + * must do the allocation at address "0" right + * now to discover where things will load so + * that we can adjust the resulting alignment. + * In this case (load_bias != 0), we can use + * MAP_FIXED_NOREPLACE to make sure the mapping + * doesn't collide with anything. + */ + if (alignment > ELF_MIN_ALIGN) { + load_bias = elf_load(bprm->file, 0, elf_ppnt, + elf_prot, elf_flags, total_size); + if (BAD_ADDR(load_bias)) { + retval = IS_ERR_VALUE(load_bias) ? + PTR_ERR((void*)load_bias) : -EINVAL; + goto out_free_dentry; + } + vm_munmap(load_bias, total_size); + /* Adjust alignment as requested. */ + if (alignment) + load_bias &= ~(alignment - 1); + elf_flags |= MAP_FIXED_NOREPLACE; + } else + load_bias = 0; + } /* * Since load_bias is used for all subsequent loading @@ -1102,31 +1162,6 @@ out_free_interp: * is then page aligned. */ load_bias = ELF_PAGESTART(load_bias - vaddr); - - /* - * Calculate the entire size of the ELF mapping - * (total_size), used for the initial mapping, - * due to load_addr_set which is set to true later - * once the initial mapping is performed. - * - * Note that this is only sensible when the LOAD - * segments are contiguous (or overlapping). If - * used for LOADs that are far apart, this would - * cause the holes between LOADs to be mapped, - * running the risk of having the mapping fail, - * as it would be larger than the ELF file itself. - * - * As a result, only ET_DYN does this, since - * some ET_EXEC (e.g. ia64) may have large virtual - * memory holes between LOADs. - * - */ - total_size = total_mapping_size(elf_phdata, - elf_ex->e_phnum); - if (!total_size) { - retval = -EINVAL; - goto out_free_dentry; - } } error = elf_load(bprm->file, load_bias + vaddr, elf_ppnt, @@ -1216,7 +1251,6 @@ out_free_interp: } reloc_func_desc = interp_load_addr; - allow_write_access(interpreter); fput(interpreter); kfree(interp_elf_ex); @@ -1251,7 +1285,7 @@ out_free_interp: mm->end_data = end_data; mm->start_stack = bprm->p; - if ((current->flags & PF_RANDOMIZE) && (randomize_va_space > 1)) { + if ((current->flags & PF_RANDOMIZE) && (snapshot_randomize_va_space > 1)) { /* * For architectures with ELF randomization, when executing * a loader directly (i.e. no interpreter listed in ELF @@ -1308,7 +1342,6 @@ out_free_dentry: kfree(interp_elf_ex); kfree(interp_elf_phdata); out_free_file: - allow_write_access(interpreter); if (interpreter) fput(interpreter); out_free_ph: |