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bh=Bt/iCncZprnekNGl7/DyAAsQ7Fn3bf5rVZDGMJUr1K4=; b=L82hC+A/6EW0y1SMt8YL4QpRTkuk1i8S8gig5J7W7V+z2nYPSHVTnRj1 6/LzSsMHw+AUcFhTim27SeNCp5odv7CaofDtay8SL5Q30IDGBZZhDntoF wHDQ3PDfP1UafnxMu20DjXTHcopvwxmiGZTcevzEq0lbksvRUFrSVpsrU kOPzfDh2EbBGImKc5+GU8ja/TrEklAeqZE/76hvqyOekuWw/S9FhaShK7 Su4L1r4c4EJPUipnJmPhcjTYmPEoUGy8ledTDJsT0P7SS5cLH/7sg3a/4 PaliTse9w+0rA0uDCoY6M2wy1SMTW6y9xTITkxZViuBXmY9s2cJxfJMJp A==; X-IronPort-AV: E=McAfee;i="6600,9927,11024"; a="6564262" X-IronPort-AV: E=Sophos;i="6.07,154,1708416000"; d="scan'208";a="6564262" Received: from orviesa004.jf.intel.com ([10.64.159.144]) by orvoesa108.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Mar 2024 19:17:15 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,154,1708416000"; d="scan'208";a="20489883" Received: from rpwilson-mobl.amr.corp.intel.com (HELO rpedgeco-desk4.intel.com) ([10.251.11.187]) by orviesa004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Mar 2024 19:17:15 -0700 From: Rick Edgecombe To: Liam.Howlett@oracle.com, akpm@linux-foundation.org, bp@alien8.de, broonie@kernel.org, christophe.leroy@csgroup.eu, dave.hansen@linux.intel.com, debug@rivosinc.com, hpa@zytor.com, keescook@chromium.org, kirill.shutemov@linux.intel.com, luto@kernel.org, mingo@redhat.com, peterz@infradead.org, tglx@linutronix.de, x86@kernel.org Cc: rick.p.edgecombe@intel.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v4 05/14] mm: Use get_unmapped_area_vmflags() Date: Mon, 25 Mar 2024 19:16:47 -0700 Message-Id: <20240326021656.202649-6-rick.p.edgecombe@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240326021656.202649-1-rick.p.edgecombe@intel.com> References: <20240326021656.202649-1-rick.p.edgecombe@intel.com> MIME-Version: 1.0 X-Stat-Signature: ozo7o8u88y4fwz93xrwadbsthzgrdams X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: AE5C7180009 X-Rspam-User: X-HE-Tag: 1711419440-348654 X-HE-Meta: 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 YV2pO7a8 P3dedOxZIBzBj1ceUdd+uUAxbQYQrSWrQQQVeSy/T77tOKco+aNMPHujSnRxOeDnheu1L6TkHmWRho+QP2V4N4EWbxm00oWF4H9RW3PmWbEzIvlPNjaZ/uR+FvQpEh+1uzSJtjvIBuNb/zjiUGmyPqJgghVWBANbTKOScp2JHbkwv5S7nf7Nvtd4xH5ULYIApID8iJ7WCT4lvZ7wBliwiy3Yw3n6U4PMEu9xln4X1Y7HgFevTju9PlMWcOkfcngvzWeopGcnY1/ttovccVsTz19pWI5HYsWBN8oZoNUmijrvQUQ8= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: When memory is being placed, mmap() will take care to respect the guard gaps of certain types of memory (VM_SHADOWSTACK, VM_GROWSUP and VM_GROWSDOWN). In order to ensure guard gaps between mappings, mmap() needs to consider two things: 1. That the new mapping isn’t placed in an any existing mappings guard gaps. 2. That the new mapping isn’t placed such that any existing mappings are not in *its* guard gaps. The long standing behavior of mmap() is to ensure 1, but not take any care around 2. So for example, if there is a PAGE_SIZE free area, and a mmap() with a PAGE_SIZE size, and a type that has a guard gap is being placed, mmap() may place the shadow stack in the PAGE_SIZE free area. Then the mapping that is supposed to have a guard gap will not have a gap to the adjacent VMA. Use mm_get_unmapped_area_vmflags() in the do_mmap() so future changes can cause shadow stack mappings to be placed with a guard gap. Also use the THP variant that takes vm_flags, such that THP shadow stack can get the same treatment. Adjust the vm_flags calculation to happen earlier so that the vm_flags can be passed into __get_unmapped_area(). Signed-off-by: Rick Edgecombe Reviewed-by: Christophe Leroy --- v4: - Split removal of get_unmapped_area() export into a separate patch (Christophe Leroy) v2: - Make get_unmapped_area() a static inline (Kirill) --- include/linux/mm.h | 11 ++++++++++- mm/mmap.c | 32 ++++++++++++++++---------------- 2 files changed, 26 insertions(+), 17 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 0436b919f1c7..8b13cd891b53 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3383,7 +3383,16 @@ extern int install_special_mapping(struct mm_struct *mm, unsigned long randomize_stack_top(unsigned long stack_top); unsigned long randomize_page(unsigned long start, unsigned long range); -extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned long, unsigned long, unsigned long); +unsigned long +__get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, + unsigned long pgoff, unsigned long flags, vm_flags_t vm_flags); + +static inline unsigned long +get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, + unsigned long pgoff, unsigned long flags) +{ + return __get_unmapped_area(file, addr, len, pgoff, flags, 0); +} extern unsigned long mmap_region(struct file *file, unsigned long addr, unsigned long len, vm_flags_t vm_flags, unsigned long pgoff, diff --git a/mm/mmap.c b/mm/mmap.c index d160e88b1b1e..68b5bfcebadd 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1255,18 +1255,6 @@ unsigned long do_mmap(struct file *file, unsigned long addr, if (mm->map_count > sysctl_max_map_count) return -ENOMEM; - /* Obtain the address to map to. we verify (or select) it and ensure - * that it represents a valid section of the address space. - */ - addr = get_unmapped_area(file, addr, len, pgoff, flags); - if (IS_ERR_VALUE(addr)) - return addr; - - if (flags & MAP_FIXED_NOREPLACE) { - if (find_vma_intersection(mm, addr, addr + len)) - return -EEXIST; - } - if (prot == PROT_EXEC) { pkey = execute_only_pkey(mm); if (pkey < 0) @@ -1280,6 +1268,18 @@ unsigned long do_mmap(struct file *file, unsigned long addr, vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) | mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; + /* Obtain the address to map to. we verify (or select) it and ensure + * that it represents a valid section of the address space. + */ + addr = __get_unmapped_area(file, addr, len, pgoff, flags, vm_flags); + if (IS_ERR_VALUE(addr)) + return addr; + + if (flags & MAP_FIXED_NOREPLACE) { + if (find_vma_intersection(mm, addr, addr + len)) + return -EEXIST; + } + if (flags & MAP_LOCKED) if (!can_do_mlock()) return -EPERM; @@ -1837,8 +1837,8 @@ unsigned long mm_get_unmapped_area_vmflags(struct mm_struct *mm, struct file *fi } unsigned long -get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, - unsigned long pgoff, unsigned long flags) +__get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, + unsigned long pgoff, unsigned long flags, vm_flags_t vm_flags) { unsigned long (*get_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long) @@ -1873,8 +1873,8 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, if (get_area) addr = get_area(file, addr, len, pgoff, flags); else - addr = mm_get_unmapped_area(current->mm, file, addr, len, - pgoff, flags); + addr = mm_get_unmapped_area_vmflags(current->mm, file, addr, len, + pgoff, flags, vm_flags); if (IS_ERR_VALUE(addr)) return addr;