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    Subject[PATCH -v2 11/16] fanotify: give a special access permission check
    Date
    add a special FANOTIFY_ACCESS_EXEC_PERM check.  This will be applied any
    place a process tries to access a file with execute permissions. Mainly
    sys_execve, sys_uselib, and mmap'ing a file for exec.

    Signed-off-by: Eric Paris <eparis@redhat.com>
    ---

    fs/aio.c | 4 ++--
    fs/exec.c | 10 ++++++++++
    fs/read_write.c | 2 +-
    include/linux/fanotify.h | 6 ++++--
    mm/mmap.c | 7 +++++++
    mm/mprotect.c | 6 ++++++
    mm/nommu.c | 7 +++++++
    7 files changed, 37 insertions(+), 5 deletions(-)

    diff --git a/fs/aio.c b/fs/aio.c
    index 008de79..6395403 100644
    --- a/fs/aio.c
    +++ b/fs/aio.c
    @@ -1455,7 +1455,7 @@ static ssize_t aio_setup_iocb(struct kiocb *kiocb)
    ret = security_file_permission(file, MAY_READ);
    if (unlikely(ret))
    break;
    - ret = fanotify(file, FAN_ACCESS_PERM);
    + ret = fanotify(file, FAN_ACCESS_NOEXEC_PERM);
    if (unlikely(ret))
    break;
    ret = aio_setup_single_vector(kiocb);
    @@ -1490,7 +1490,7 @@ static ssize_t aio_setup_iocb(struct kiocb *kiocb)
    ret = security_file_permission(file, MAY_READ);
    if (unlikely(ret))
    break;
    - ret = fanotify(file, FAN_ACCESS_PERM);
    + ret = fanotify(file, FAN_ACCESS_NOEXEC_PERM);
    if (unlikely(ret))
    break;
    ret = aio_setup_vectored_rw(READ, kiocb);
    diff --git a/fs/exec.c b/fs/exec.c
    index 3612805..ab45d65 100644
    --- a/fs/exec.c
    +++ b/fs/exec.c
    @@ -140,6 +140,11 @@ asmlinkage long sys_uselib(const char __user * library)
    goto out;

    fsnotify_open_exec(file);
    + error = fanotify(file, FAN_ACCESS_EXEC_PERM);
    + if (error) {
    + fput(file);
    + goto out;
    + }

    error = -ENOEXEC;
    if(file->f_op) {
    @@ -694,6 +699,11 @@ struct file *open_exec(const char *name)
    return file;

    fsnotify_open_exec(file);
    + err = fanotify(file, FAN_ACCESS_EXEC_PERM);
    + if (err) {
    + fput(file);
    + goto out;
    + }

    err = deny_write_access(file);
    if (err) {
    diff --git a/fs/read_write.c b/fs/read_write.c
    index a74cf76..8ab4646 100644
    --- a/fs/read_write.c
    +++ b/fs/read_write.c
    @@ -203,7 +203,7 @@ int rw_verify_area(int read_write, struct file *file, loff_t *ppos, size_t count
    if (retval)
    return retval;
    if (read_write == READ) {
    - retval = fanotify(file, FAN_ACCESS_PERM);
    + retval = fanotify(file, FAN_ACCESS_NOEXEC_PERM);
    if (retval)
    return retval;
    }
    diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
    index 0405e4c..07b8e77 100644
    --- a/include/linux/fanotify.h
    +++ b/include/linux/fanotify.h
    @@ -18,8 +18,9 @@
    #define FAN_OPEN_EXEC 0x00000020 /* File was opened with the intention of being exec'ed */

    /* userspace may also request blocking for permission checks for open and read */
    -#define FAN_ACCESS_PERM 0x00000100
    -#define FAN_OPEN_PERM 0x00000200
    +#define FAN_ACCESS_NOEXEC_PERM 0x00000100
    +#define FAN_ACCESS_EXEC_PERM 0x00000200
    +#define FAN_OPEN_PERM 0x00000400

    /* FIXME currently Q's have no limit.... */
    #define FAN_Q_OVERFLOW 0x80000000 /* Event queued overflowed */
    @@ -27,6 +28,7 @@
    /* helper events */
    #define FAN_CLOSE (FAN_CLOSE_WRITE | FAN_CLOSE_NOWRITE) /* close */
    #define FAN_OPEN (FAN_OPEN_NOEXEC | FAN_OPEN_EXEC) /* open */
    +#define FAN_ACCESS_PERM (FAN_ACCESS_NOEXEC_PERM | FAN_ACCESS_EXEC_PERM) /* access perm */

    /*
    * All of the events - we build the list by hand so that we can add flags in
    diff --git a/mm/mmap.c b/mm/mmap.c
    index e7a5a68..35d051f 100644
    --- a/mm/mmap.c
    +++ b/mm/mmap.c
    @@ -18,6 +18,7 @@
    #include <linux/init.h>
    #include <linux/file.h>
    #include <linux/fs.h>
    +#include <linux/fanotify.h>
    #include <linux/personality.h>
    #include <linux/security.h>
    #include <linux/hugetlb.h>
    @@ -1027,6 +1028,12 @@ unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
    default:
    return -EINVAL;
    }
    +
    + if (prot & PROT_EXEC) {
    + error = fanotify(file, FAN_ACCESS_EXEC_PERM);
    + if (error)
    + return error;
    + }
    } else {
    switch (flags & MAP_TYPE) {
    case MAP_SHARED:
    diff --git a/mm/mprotect.c b/mm/mprotect.c
    index fded06f..af1da2d 100644
    --- a/mm/mprotect.c
    +++ b/mm/mprotect.c
    @@ -16,6 +16,7 @@
    #include <linux/fs.h>
    #include <linux/highmem.h>
    #include <linux/security.h>
    +#include <linux/fanotify.h>
    #include <linux/mempolicy.h>
    #include <linux/personality.h>
    #include <linux/syscalls.h>
    @@ -294,6 +295,11 @@ sys_mprotect(unsigned long start, size_t len, unsigned long prot)
    if (error)
    goto out;

    + if (vma->vm_file && (prot & PROT_EXEC))
    + error = fanotify(vma->vm_file, FAN_ACCESS_EXEC_PERM);
    + if (error)
    + goto out;
    +
    tmp = vma->vm_end;
    if (tmp > end)
    tmp = end;
    diff --git a/mm/nommu.c b/mm/nommu.c
    index ed75bc9..f541693 100644
    --- a/mm/nommu.c
    +++ b/mm/nommu.c
    @@ -18,6 +18,7 @@
    #include <linux/mman.h>
    #include <linux/swap.h>
    #include <linux/file.h>
    +#include <linux/fanotify.h>
    #include <linux/highmem.h>
    #include <linux/pagemap.h>
    #include <linux/slab.h>
    @@ -709,6 +710,12 @@ static int validate_mmap_request(struct file *file,
    /* backing file is not executable, try to copy */
    capabilities &= ~BDI_CAP_MAP_DIRECT;
    }
    +
    + if (prot & PROT_EXEC) {
    + ret = fanotify(file, FAN_ACCESS_EXEC_PERM);
    + if (ret)
    + return ret;
    + }
    }
    else {
    /* anonymous mappings are always memory backed and can be


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