2.6.32-longterm review patch. If anyone has any objections, please let me know. ------------------ commit 1c90308e7a77af6742a97d1021cca923b23b7f0d upstream. This patch makes pagemap readable for normal users and hides physical addresses from them. For some use-cases PFN isn't required at all. See http://lkml.kernel.org/r/1425935472-17949-1-git-send-email-kirill@xxxxxxxxxxxxx Fixes: ab676b7d6fbf ("pagemap: do not leak physical addresses to non-privileged userspace") Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx> Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> Reviewed-by: Mark Williamson <mwilliamson@xxxxxxxxxxxxxxxxx> Tested-by: Mark Williamson <mwilliamson@xxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> [bwh: Backported to 3.2: - Add the same check in the places where we look up a PFN - Add struct pagemapread * parameters where necessary - Open-code file_ns_capable() - Delete pagemap_open() entirely, as it would always return 0] Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> (cherry picked from commit b1fb185f26e85f76e3ac6ce557398d78797c9684) [wt: adjusted context, no pagemap_hugetlb_range() in 2.6.32, and security_capable() only takes a capability. Tested OK. ] Signed-off-by: Willy Tarreau <w@xxxxxx> --- fs/proc/task_mmu.c | 21 ++++++++------------- 1 file changed, 8 insertions(+), 13 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 73db5a6..78658aa 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -8,6 +8,7 @@ #include <linux/mempolicy.h> #include <linux/swap.h> #include <linux/swapops.h> +#include <linux/security.h> #include <asm/elf.h> #include <asm/uaccess.h> @@ -539,6 +540,7 @@ const struct file_operations proc_clear_refs_operations = { struct pagemapread { u64 __user *out, *end; + bool show_pfn; }; #define PM_ENTRY_BYTES sizeof(u64) @@ -589,14 +591,14 @@ static u64 swap_pte_to_pagemap_entry(pte_t pte) return swp_type(e) | (swp_offset(e) << MAX_SWAPFILES_SHIFT); } -static u64 pte_to_pagemap_entry(pte_t pte) +static u64 pte_to_pagemap_entry(struct pagemapread *pm, pte_t pte) { u64 pme = 0; if (is_swap_pte(pte)) pme = PM_PFRAME(swap_pte_to_pagemap_entry(pte)) | PM_PSHIFT(PAGE_SHIFT) | PM_SWAP; else if (pte_present(pte)) - pme = PM_PFRAME(pte_pfn(pte)) + pme = (pm->show_pfn ? PM_PFRAME(pte_pfn(pte)) : 0) | PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT; return pme; } @@ -624,7 +626,7 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, if (vma && (vma->vm_start <= addr) && !is_vm_hugetlb_page(vma)) { pte = pte_offset_map(pmd, addr); - pfn = pte_to_pagemap_entry(*pte); + pfn = pte_to_pagemap_entry(pm, *pte); /* unmap before userspace copy */ pte_unmap(pte); } @@ -695,6 +697,9 @@ static ssize_t pagemap_read(struct file *file, char __user *buf, if (!count) goto out_task; + /* do not disclose physical addresses: attack vector */ + pm.show_pfn = !security_capable(CAP_SYS_ADMIN); + mm = get_task_mm(task); if (!mm) goto out_task; @@ -773,19 +778,9 @@ out: return ret; } -static int pagemap_open(struct inode *inode, struct file *file) -{ - /* do not disclose physical addresses to unprivileged - userspace (closes a rowhammer attack vector) */ - if (!capable(CAP_SYS_ADMIN)) - return -EPERM; - return 0; -} - const struct file_operations proc_pagemap_operations = { .llseek = mem_lseek, /* borrow this */ .read = pagemap_read, - .open = pagemap_open, }; #endif /* CONFIG_PROC_PAGE_MONITOR */ -- 1.7.12.2.21.g234cd45.dirty -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html