Apply noexec mount option for mmap(PROT_EXEC).
Right now the noexec mount option disallows image activators to try execve the files on the mount point. Also, after r127187, noexec also limits max_prot map entries permissions for mappings of files from such mounts, but not the actual mapping permissions. As result, the API behaviour is inconsistent. The files from noexec mount can be mapped with PROT_EXEC, but if mprotect(2) drops execution permission, it cannot be re-enabled later. Make this consistent logically and aligned with behaviour of other systems, by disallowing PROT_EXEC for mmap(2). Note that this change only ensures aligned results from mmap(2) and mprotect(2), it does not prevent actual code execution from files coming from noexec mount. Such files can always be read into anonymous executable memory and executed from there. Reported by: shamaz.mazum@gmail.com PR: 217062 Reviewed by: alc Sponsored by: The FreeBSD Foundation MFC after: 1 week
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=313967
@ -1803,9 +1803,11 @@ devfs_mmap_f(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t size,
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* compatible.
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*/
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mp = vp->v_mount;
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if (mp != NULL && (mp->mnt_flag & MNT_NOEXEC) != 0)
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if (mp != NULL && (mp->mnt_flag & MNT_NOEXEC) != 0) {
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maxprot = VM_PROT_NONE;
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else
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if ((prot & VM_PROT_EXECUTE) != 0)
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return (EACCES);
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} else
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maxprot = VM_PROT_EXECUTE;
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if ((fp->f_flag & FREAD) != 0)
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maxprot |= VM_PROT_READ;
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@ -2430,9 +2430,11 @@ vn_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t size,
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* proc does a setuid?
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*/
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mp = vp->v_mount;
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if (mp != NULL && (mp->mnt_flag & MNT_NOEXEC) != 0)
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if (mp != NULL && (mp->mnt_flag & MNT_NOEXEC) != 0) {
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maxprot = VM_PROT_NONE;
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else
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if ((prot & VM_PROT_EXECUTE) != 0)
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return (EACCES);
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} else
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maxprot = VM_PROT_EXECUTE;
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if ((fp->f_flag & FREAD) != 0)
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maxprot |= VM_PROT_READ;
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