pipe, sysctl: drop 'min' parameter from pipe-max-size converter
commit 4c2e4befb3cc9ce42d506aa537c9ab504723e98c upstream. Patch series "pipe: buffer limits fixes and cleanups", v2. This series simplifies the sysctl handler for pipe-max-size and fixes another set of bugs related to the pipe buffer limits: - The root user wasn't allowed to exceed the limits when creating new pipes. - There was an off-by-one error when checking the limits, so a limit of N was actually treated as N - 1. - F_SETPIPE_SZ accepted values over UINT_MAX. - Reading the pipe buffer limits could be racy. This patch (of 7): Before validating the given value against pipe_min_size, do_proc_dopipe_max_size_conv() calls round_pipe_size(), which rounds the value up to pipe_min_size. Therefore, the second check against pipe_min_size is redundant. Remove it. Link: http://lkml.kernel.org/r/20180111052902.14409-2-ebiggers3@gmail.com Signed-off-by: Eric Biggers <ebiggers@google.com> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: "Luis R . Rodriguez" <mcgrof@kernel.org> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Mikulas Patocka <mpatocka@redhat.com> Cc: Willy Tarreau <w@1wt.eu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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bae0262aef
10
fs/pipe.c
10
fs/pipe.c
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@ -34,11 +34,6 @@
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*/
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unsigned int pipe_max_size = 1048576;
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/*
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* Minimum pipe size, as required by POSIX
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*/
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unsigned int pipe_min_size = PAGE_SIZE;
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/* Maximum allocatable pages per user. Hard limit is unset by default, soft
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* matches default values.
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*/
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@ -1222,8 +1217,9 @@ unsigned int round_pipe_size(unsigned int size)
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{
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unsigned long nr_pages;
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if (size < pipe_min_size)
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size = pipe_min_size;
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/* Minimum pipe size, as required by POSIX */
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if (size < PAGE_SIZE)
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size = PAGE_SIZE;
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nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
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if (nr_pages == 0)
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@ -141,7 +141,7 @@ void pipe_lock(struct pipe_inode_info *);
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void pipe_unlock(struct pipe_inode_info *);
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void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *);
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extern unsigned int pipe_max_size, pipe_min_size;
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extern unsigned int pipe_max_size;
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extern unsigned long pipe_user_pages_hard;
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extern unsigned long pipe_user_pages_soft;
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int pipe_proc_fn(struct ctl_table *, int, void __user *, size_t *, loff_t *);
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@ -1961,7 +1961,6 @@ static struct ctl_table fs_table[] = {
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = &pipe_proc_fn,
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.extra1 = &pipe_min_size,
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},
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{
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.procname = "pipe-user-pages-hard",
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@ -2471,15 +2470,9 @@ int proc_dointvec_minmax(struct ctl_table *table, int write,
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do_proc_dointvec_minmax_conv, ¶m);
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}
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struct do_proc_dopipe_max_size_conv_param {
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unsigned int *min;
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};
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static int do_proc_dopipe_max_size_conv(bool *negp, unsigned long *lvalp,
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int *valp, int write, void *data)
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{
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struct do_proc_dopipe_max_size_conv_param *param = data;
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if (write) {
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unsigned int val;
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@ -2490,9 +2483,6 @@ static int do_proc_dopipe_max_size_conv(bool *negp, unsigned long *lvalp,
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if (*negp || val == 0)
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return -EINVAL;
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if (param->min && *param->min > val)
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return -ERANGE;
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*valp = val;
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} else {
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unsigned int val = *valp;
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@ -2506,11 +2496,8 @@ static int do_proc_dopipe_max_size_conv(bool *negp, unsigned long *lvalp,
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int proc_dopipe_max_size(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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struct do_proc_dopipe_max_size_conv_param param = {
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.min = (unsigned int *) table->extra1,
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};
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return do_proc_dointvec(table, write, buffer, lenp, ppos,
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do_proc_dopipe_max_size_conv, ¶m);
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do_proc_dopipe_max_size_conv, NULL);
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}
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static void validate_coredump_safety(void)
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